CD8-positive T cells are the immune system’s specialized assassins, programmed to recognize and destroy cells that display foreign or abnormal signals on their surfaces, whether those signals come from viruses or from cancerous mutations. Under normal circumstances, these cells mount a vigorous response, proliferating rapidly and releasing toxic molecules that kill infected or malignant targets. But when the stimulation persists for weeks or months, as it does in chronic viral infections and in solid tumors that continuously present antigens, the T cells receive a prolonged barrage of activation signals that pushes them into an overstimulated state. Rather than becoming stronger, they become exhausted: they lose their ability to proliferate, secrete fewer of the cytokines needed to coordinate an attack, and effectively stand down while the tumor or virus continues to progress.

One of the critical signals in this process is interleukin-2, or IL-2, a cytokine that normally fuels T-cell activation and expansion. The St. Jude researchers discovered that exhausted T cells receive suboptimal activation through IL-2 signaling, and that this deficiency is not an accident of the tumor environment but the result of an active genetic program. Their search for the molecular link between chronic overstimulation and exhaustion led them directly to ZMYND8, a protein that normally functions as a transcriptional brake, repressing the expression of certain genes. Among the genes it suppresses is Il2ra, which encodes the IL-2 receptor, the very molecular antenna T cells need to respond to IL-2. In other words, chronic stimulation co-opts ZMYND8 to silence the receptor that would otherwise keep the T cells fighting.

Chi described the significance of the finding in stark terms. “Now we may have a way to overcome CD8-positive T-cell exhaustion and improve their function,” he said in the announcement accompanying the study. “When we deleted Zmynd8, we saw improved CD8-positive T-cell function against tumors and chronic infections, suggesting we may have a new therapeutic target to explore to improve these therapies.” The experiments showed that removing the gene from CD8-positive T cells in mice led to significantly better control of both chronic viral infection and melanoma compared with control animals, demonstrating that the effect holds across two distinct disease contexts that share the same underlying problem of persistent antigen stimulation.

To identify ZMYND8 in the first place, the team employed single-cell CRISPR screening, a technique that allows researchers to systematically knock out individual genes across large populations of cells and observe the consequences in each cell individually. By removing genes involved in regulating gene expression and tracking how T-cell states changed, the scientists could pinpoint which regulators were driving the transition into exhaustion. ZMYND8 stood out from the crowd. “We found that ZMYND8 is a ‘master’ regulator of CD8-positive T-cell exhaustion,” said co-first author Yan Wang, PhD, of the St. Jude Department of Immunology. “Its deletion enhanced effector cell formation, leading to the improved anti-tumor and anti-viral effects we observed.” The term master regulator reflects the gene’s position at a control point that shapes the entire fate of the cell, rather than merely tweaking one downstream pathway.

Having identified the master regulator, the researchers then dissected the mechanism by which it exerts its influence. They found that ZMYND8 physically binds to and suppresses the activity of p300, a well-known transcriptional coactivator that controls the activation of the IL-2 receptor gene. When ZMYND8 is present during chronic stimulation, it clamps down on p300’s ability to drive Il2ra expression, starving the T cell of the IL-2 signaling it needs to maintain its effector identity. “ZMYND8 can transform the chronic antigen stimulation signal that occurs in chronic viral infections and cancer into suppression of IL-2 receptor signaling, leading to an exhausted cell state,” explained co-first author Hao Shi, PhD, also of the St. Jude Department of Immunology. This mechanistic clarity is what elevates the finding beyond a simple correlation: the researchers can now trace a complete pathway from persistent antigen exposure through ZMYND8 recruitment, p300 suppression, IL-2 receptor silencing, and finally the exhausted state itself.

The most clinically exciting results came when the researchers combined Zmynd8 deletion with established immunotherapy approaches. Immune checkpoint blockade, the class of drugs that includes agents targeting PD-1 and CTLA-4, works by releasing a different kind of brake, one that cancers exploit to hide from immune attack. The St. Jude team tested Zmynd8 deletion in CD8-positive T cells alongside checkpoint blockade and separately alongside IL-2 supplementation. In both combinations, they observed an increase in functional effector cells, a corresponding decrease in exhausted cells, and a more profound increase in survival among mice receiving the combined treatments than in mice receiving either intervention alone. “What we’re really excited about is how the combination with immunotherapy enhanced treatment efficacy,” Chi noted, underscoring that the gene deletion did not merely add to the effects of immunotherapy but appeared to multiply them.

The synergy makes biological sense in light of the mechanism. Checkpoint blockade reinvigorates T cells that have already become partially dysfunctional, but if those cells remain unable to respond to IL-2 because ZMYND8 has silenced their receptors, the reinvigoration is incomplete. By removing the ZMYND8 brake, the T cells regain the capacity to receive IL-2 signals, and the checkpoint drugs or IL-2 therapy can then act on cells that are actually equipped to respond. This dual approach addresses both the external brakes that tumors impose and the internal brake that T cells impose on themselves, a combination that may prove essential for solid tumors, which have proven far more resistant to immunotherapy than blood cancers.

The implications for pediatric oncology are particularly significant. Immunotherapy has increased survival for some adults and children with cancer, but its success against many pediatric solid tumors has been limited, in part because T cells in those patients become exhausted before they can clear the disease. A strategy that prevents or reverses exhaustion at the genetic level could expand the population of children who benefit from these treatments. Chi emphasized this translational potential: “We have a new approach that could synergize with immunotherapy. One day, a combination treatment approach could improve survival for patients with solid tumors.”

The study, published in Nature on September 23, 2026, was supported by grants from the National Institutes of Health, including CA253188, AI105887, AI131703, AI140761, AI150241 and AI150514, along with the Cancer Center Support Grant P30 CA021765 and funding from the American Lebanese Syrian Associated Charities, the fundraising and awareness organization of St. Jude. In addition to Chi, Wang and Shi, the research team included Nicole Chapman, Anil KC, Renqiang Sun and Hao Song of St. Jude, and Xiaoxi Meng and Xiang Sun, formerly of the institution. The work represents a growing trend in immunology research: rather than simply boosting immune activation with cytokines or checkpoint inhibitors, scientists are now mapping the intrinsic gene programs that determine whether T cells sustain or surrender their function, and using that map to design interventions that reprogram the cells themselves. If the mouse findings translate to humans, targeting ZMYND8 or the p300-IL-2 receptor axis it controls could become a cornerstone of next-generation cancer immunotherapy.

Subject of Research: The role of the ZMYND8 gene in regulating CD8-positive T-cell exhaustion and its potential as an immunotherapy target

Article Title: Targeting ZMYND8 improves T-cell function and may boost immunotherapy

Article References: Targeting ZMYND8 improves T-cell function and may boost immunotherapy. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: ZMYND8, T-cell exhaustion, CD8-positive T cells, immunotherapy, interleukin-2, p300, checkpoint blockade, St. Jude Children's Research Hospital, solid tumors, chronic viral infection, CRISPR screening, Nature

Cell therapy is one of the most promising advances in modern cancer treatment. The basic concept involves collecting a patient’s own immune cells, genetically reprogramming them in the laboratory so they recognize cancer more effectively, and then infusing them back into the patient’s body. Once circulating, these enhanced immune cells are designed to seek out and destroy cancer cells while leaving healthy tissue largely untouched. The approach has already produced remarkable results in certain blood cancers, where engineered CAR T-cell therapies have driven durable remissions in patients who had exhausted conventional options. Translating that success to solid tumors, however, has proven far more difficult. Solid tumors build defensive microenvironments that suppress immune activity, physically exclude T cells and exhaust the cells that do manage to infiltrate. The new UChicago Medicine trial is designed specifically to confront those barriers, combining tumor recognition with engineered resistance to the immunosuppressive signals that tumors deploy.

The scientific foundation of the treatment differs in an important way from existing CAR T-cell platforms. Conventional CAR T cells use engineered synthetic receptors that recognize proteins displayed on the surface of cancer cells. The UChicago team, by contrast, is using specially engineered T-cell receptors, the natural antigen-recognition machinery of the immune system, which allow immune cells to detect protein fragments presented from inside cancer cells. This distinction matters enormously for the range of cancers that can be targeted. Many of the most attractive tumor-associated proteins are not displayed on the cell surface but are processed internally and presented on major histocompatibility complex molecules, invisible to CAR constructs but perfectly visible to a properly directed T-cell receptor. By exploiting this intracellular surveillance pathway, the researchers dramatically expand the universe of tumors that engineered cell therapies might plausibly attack.

Richard Koya, MD, PhD, Professor of Obstetrics and Gynecology at UChicago Medicine, is the scientific investigator who developed the treatment and designed the clinical trial on the basis of many years of laboratory research. He framed the strategy as an extension of the immune system’s own logic. The team, he explained, is using the same natural process the immune system relies on to fight infections, but redirecting it to attack cancer. The stated goal is to create immune cells that can recognize cancer more effectively, survive longer and continue fighting the disease over time. That emphasis on persistence reflects a central lesson of immunotherapy research: engineered cells that fade quickly or become dysfunctional inside tumors rarely produce lasting benefit, whereas cells that endure and form immune memory may hold tumors in check long after the initial infusion.

The treatment protocol unfolds in several carefully sequenced stages. Doctors will first collect a patient’s white blood cells through a process similar to blood donation. Patients will then receive the chemotherapy drug decitabine, chosen for a specific biological effect: it increases the production of a cancer protein called NY-ESO-1, a target found in many tumors but absent from healthy adult tissues. This priming step is intended to make tumor cells more visible to the engineered immune cells that will follow. In the laboratory, researchers will then genetically engineer the patient’s immune cells with two critical features. The first is a T-cell receptor that recognizes NY-ESO-1, equipping the cells to identify and attack cancer. The second is a genetic modification that blocks TGF-beta, a signaling molecule that normally suppresses immune responses and contributes to T-cell exhaustion inside tumors, one of the principal reasons cell therapies have underperformed against solid disease.

Once the engineering is complete, the enhanced immune cells will be infused back into the patient through an intravenous line, much like a blood transfusion. Patients will also receive a low dose of interleukin-2, an immune-boosting drug that helps the engineered T cells multiply and remain active after they enter the body. The investigators plan to infuse approximately one billion engineered T cells into each patient, a dose intended to generate a powerful and durable immune response against cancers that currently have few effective treatment options. Researchers believe this combination, antigen targeting, resistance to suppressive signaling and cytokine support, could produce a stronger and longer-lasting immune response because it addresses one of the biggest challenges in solid tumor treatment: the hostile tumor environment that often weakens cancer-fighting immune cells before they can eliminate the tumor. By engineering T cells to resist signals such as TGF-beta, the team hopes the cells will persist longer, develop lasting immune memory and continue attacking tumors over time.

The trial’s design and execution are notable for their institutional provenance. This is an investigator-initiated clinical trial, meaning the treatment was conceived and developed by University of Chicago researchers rather than a commercial sponsor. The UChicago Medicine Comprehensive Cancer Center, which operates one of the nation’s largest cancer clinical trials programs, has extensive experience translating laboratory discoveries into early-stage clinical studies, and that infrastructure is now being applied to a therapy the institution controls end to end. Critically, the engineered cells will be produced in UChicago Medicine’s Good Manufacturing Practices facility, a highly specialized laboratory that meets strict federal standards for producing cell therapies. On-site manufacturing allows researchers to oversee every step of the process, maintain quality control and accelerate the translation of discoveries from the laboratory to patients, a capability that very few academic medical centers possess.

Koya emphasized the strategic value of that capability. Very few academic medical centers, he noted, have the ability to manufacture personalized cell therapies entirely on-site, and he described the arrangement as giving the team tremendous flexibility to rapidly test new ideas and move promising treatments to patients. That flexibility is particularly consequential in the fast-moving field of cellular immunotherapy, where iterative design changes, new receptor constructs and combination strategies often emerge faster than commercial pipelines can accommodate. An academic GMP facility effectively shortens the distance between a laboratory observation and a patient-ready product, allowing investigators to refine the therapy across successive cohorts in ways that industry-sponsored trials, bound by fixed manufacturing contracts and regulatory timelines, often cannot.

The Phase 1/2A trial will evaluate the experimental therapy in a small group of patients with metastatic ovarian cancer, soft tissue sarcoma, bladder cancer, prostate cancer, breast cancer, melanoma or non-small cell lung cancer, all cancers that form solid tumors and all diseases in which effective options narrow sharply once the disease has spread. Beginning in October 2026, screening for eligible patients will take place at UChicago Medicine locations in Hyde Park, New Lenox, Harvey, Flossmoor, Calumet City and Tinley Park in Illinois, and Crown Point in Indiana, with treatment taking place at the main campus in Hyde Park. UChicago Medicine oncologist Daniel Olson, MD, Assistant Professor of Medicine, is the clinical investigator overseeing the trial, while Thinle Chodon, MD, PhD, research professor, is overseeing production of the engineered cells in the institution’s GMP facility. The division of roles between clinical leadership and manufacturing oversight reflects the operational complexity of personalized cell therapy, in which each patient’s product is a bespoke biological medicine.

The launch arrives as UChicago Medicine continues to expand its cancer care and research enterprise. The institution was among the first medical centers in the country to offer FDA-approved CAR T-cell therapy for adults and children with certain blood cancers, and more recently became one of the first centers to provide tumor-infiltrating lymphocyte therapy for advanced melanoma, establishing a track record at the leading edge of cellular immunology. In April 2027, UChicago Medicine will open the AbbVie Foundation Cancer Pavilion, Chicago’s first freestanding cancer pavilion, intended to bring advanced diagnostics, innovative treatments, translational discoveries and comprehensive support services to patients and the surrounding community. For patients with advanced solid tumors, the new trial offers something more immediate: a chance to access an immunotherapy approach that targets hidden tumor proteins, resists the suppressive forces of the tumor microenvironment and is produced by the same institution treating them, a model of academic self-reliance that may shape how the next generation of cancer cell therapies reaches the clinic.

Subject of Research: A Phase 1/2A clinical trial of an investigator-developed engineered T-cell receptor therapy targeting NY-ESO-1 for advanced solid tumors

Article Title: UChicago Medicine launches homegrown cell therapy for advanced solid tumors

Article References: UChicago Medicine launches homegrown cell therapy for advanced solid tumors. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: cell therapy, T-cell receptor, solid tumors, NY-ESO-1, TGF-beta, ovarian cancer, CAR T-cell therapy, GMP manufacturing, clinical trial, immunotherapy, decitabine, interleukin-2

The logic of TIL therapy rests on a simple observation: many tumors are not immunological deserts. Immune cells, particularly T lymphocytes, physically penetrate tumor tissue, where they can recognize mutated or aberrantly expressed proteins and kill the malignant cells they encounter. The therapeutic strategy involves harvesting a piece of the patient’s tumor, isolating the lymphocytes trapped inside, expanding them to billions of cells in the laboratory, and then reinfusing this amplified army back into the patient, usually after lymphodepleting chemotherapy creates immunological space. The approach has produced durable complete responses in a substantial fraction of advanced melanoma patients and is being tested in cervical cancer, lung cancer, and sarcomas. Whether it could work in NF1- and SWN-related tumors, however, had never been systematically examined, leaving a significant gap for a patient population with few options.

The first question the researchers addressed was whether these tumors actually harbor the T cell infiltrates that TIL therapy requires. They examined 109 clinical specimens spanning the disease spectrum, including benign neurofibromas from NF1 patients, schwannomas from SWN patients, and MPNSTs. Using immunohistochemistry to detect the pan-T cell marker CD3, they found moderate to high T cell infiltration in the overwhelming majority of samples: 84.0 percent of neurofibromas, 98.3 percent of schwannomas, and 75.0 percent of MPNSTs. This was a critical finding, because it established the biological prerequisite for the therapy. If the tumors had been largely devoid of T cells, harvesting and expanding meaningful numbers of tumor-reactive lymphocytes would have been futile. Instead, the data suggested that immune cells are already trafficking into these lesions in most patients, presumably drawn by tumor-associated antigens.

With the rationale established, the team turned to the practical challenge of growing these cells outside the body. Traditional TIL manufacturing relies on high-dose interleukin-2 (IL-2), a potent growth factor that drives T cell proliferation but can also skew the resulting cell population, exhaust the cells, and lengthen production times. The researchers developed an alternative protocol, designated OM-400, that combines stimulation through CD3 and CD28, the two key signaling receptors on T cells, using antibody-coated beads, with a much lower dose of IL-2 at 400 international units per milliliter. The CD3/CD28 co-stimulation mimics the two signals a T cell normally receives when it recognizes its target, providing activation in a more physiological manner than flooding the culture with cytokine alone.

The results of the head-to-head comparison were striking. OM-400 achieved successful expansion in 100 percent of the TIL cultures derived from NF1/SWN-related nerve sheath tumors, whereas the traditional high-dose IL-2 method did not consistently reach that benchmark. The new protocol also shortened the time required to grow the cells to therapeutic numbers, an important consideration for patients with aggressive MPNSTs who cannot afford to wait weeks for a product. Flow cytometric analysis showed that OM-400 cultures were enriched for CD8-positive effector T cells, the cytotoxic subset responsible for directly killing tumor cells. In an analysis of one representative specimen, the protocol also showed preliminary evidence of better preservation of the original T cell receptor (TCR) repertoire, meaning the diverse array of antigen-recognition specificities present in the patient’s tumor was maintained through the expansion process rather than being narrowed by overgrowth of a few clones.

Functionally, the OM-400-expanded cells proved more potent. When co-cultured with autologous tumor cells, meaning tumor cells taken from the same patient whose lymphocytes were being expanded, the cells produced under the new protocol showed enhanced tumor-reactive cytotoxicity, killing more cancer cells than their conventionally grown counterparts. They also secreted higher levels of interferon-gamma (IFN-γ), a signature inflammatory cytokine released when T cells genuinely recognize their targets. Together, these assays indicated that the OM-400 product was not merely larger in number but qualitatively better: more cytotoxic, more tumor-reactive, and more faithful to the immune landscape of the original tumor.

An important exploratory analysis examined whether the type of tumor influenced TIL performance. The team compared results across 15 independent patient samples covering NF1-related neurofibromas, SWN-related schwannomas, and NF1-related MPNSTs. No statistically significant differences emerged among the subtypes, suggesting that a single manufacturing platform might serve the entire disease spectrum. The authors are careful to note, however, that the study was not powered to establish equivalence, and larger cohorts will be needed to definitively assess whether tumor subtype affects TIL yield, phenotype, or reactivity. This caveat reflects the rarity of these conditions; collecting large numbers of fresh surgical specimens from NF1 and SWN patients is inherently difficult, making the 15-sample dataset a meaningful start rather than a final answer.

The decisive test came in animal models. The researchers used patient-derived xenografts (PDX), in which fragments of an MPNST patient’s tumor are implanted into immunodeficient mice, preserving the molecular characteristics of the original cancer. When OM-400-expanded TILs were delivered to these tumor-bearing mice, the cells successfully infiltrated the tumor tissue, a nontrivial requirement since many cell therapies fail because they cannot physically reach and penetrate the tumor mass. More importantly, the treated animals showed significant suppression of tumor growth compared with controls. This in vivo efficacy demonstrated that the laboratory-manufactured cells retained their killing capacity in a living biological system, not just in a culture dish, and provided the strongest evidence yet that the approach could translate to patients.

The significance of the work extends beyond a single protocol. NF1 affects approximately one in 2,500 to 3,000 births worldwide, and while most neurofibromas are benign, they can cause disfigurement, pain, and neurological deficits, and a subset progresses to life-threatening MPNSTs, for which five-year survival remains poor even with aggressive surgery, radiation, and chemotherapy. Recent years have seen encouraging but limited progress with targeted agents such as MEK inhibitors for inoperable plexiform neurofibromas, yet MPNST has remained essentially untouched by systemic therapy. A cellular immunotherapy platform that works across the NF1/SWN tumor spectrum would represent an entirely new therapeutic modality for these patients, and one that could in principle be personalized to each individual’s tumor.

Considerable work remains before the first patient receives an infusion. The study is preclinical, and the transition from PDX mice to human trials will require regulatory-grade manufacturing, safety testing, and careful attention to questions the current data cannot answer, such as the durability of responses, the optimal lymphodepletion regimen, and whether the TCR repertoire preservation seen in a single representative specimen holds broadly. The authors emphasize that their contribution is a reproducible manufacturing platform and a proof of biological feasibility, the foundations on which clinical translation can now be built. For a community of patients who have watched decades of research yield few new options, the demonstration that their tumors are infiltrated by T cells that can be grown, armed, and sent back to fight is a milestone worth noting, and one that turns a long-standing immunological question into a concrete path toward the clinic.

Subject of Research: Tumor-infiltrating lymphocyte immunotherapy for NF1/SWN-related nerve sheath tumors

Article Title: Development of TIL therapy for NF1/SWN-related nerve sheath tumors

Article References: Hao, J., Cheng, L., Zhang, C., Wang, J., Wang, H., Wu, H., & Tang, N. (2026). Development of TIL therapy for NF1/SWN-related nerve sheath tumors. Cancer Immunology, Immunotherapy. https://doi.org/10.1007/s00262-026-04595-6

Image Credits: AI Generated

DOI: 10.1007/s00262-026-04595-6

Keywords: TIL therapy, NF1, schwannomatosis, MPNST, adoptive cell therapy, immunotherapy, patient-derived xenograft, CD8 T cells, interleukin-2, TCR repertoire, nerve sheath tumors, preclinical study

The study, led by Daniel Arroyo-Sánchez and Oscar Cabrera-Marante of the Immunology Department at Hospital Universitario 12 de Octubre and published in the Journal of Translational Medicine, set out to answer a deceptively simple question: what happens to the B cells of CVID patients when they are pushed to produce antibodies under controlled laboratory conditions? To find out, the researchers isolated peripheral blood mononuclear cells, the mixed population of immune cells circulating in the blood, from 20 patients with CVID and from healthy donors. These cells were then cultured in the laboratory with a carefully chosen cocktail of stimuli: interleukin-2, a cytokine that supports lymphocyte survival and proliferation, and R848, a synthetic compound that activates Toll-like receptors, the molecular sensors that normally alert B cells to microbial invasion and drive them toward antibody-secreting states.

The choice of stimulation is scientifically significant. Toll-like receptor signaling has become an increasingly important focus in immunodeficiency research because it mimics a key pathway used during natural infection and, notably, during vaccination. Recent clinical observations had shown that some CVID patients mount partial responses to mRNA vaccines, hinting that a residue of functional capacity might survive within their B-cell compartment. By combining IL-2 with R848, the team created conditions designed to coax out whatever antibody-producing potential the patients’ cells still possessed, and then to measure precisely how far that potential could carry them.

The results, tracked over a ten-day culture period, revealed a striking temporal pattern. In cultures from healthy controls, antibodies remained readily detectable in the culture supernatants throughout the observation window, a sign that the cells had successfully differentiated into antibody-secreting cells and sustained their output. In cultures from CVID patients, by contrast, the ability to sustain antibody production collapsed. By day 10, the patients’ cultures had failed to maintain antibody secretion, and the cellular composition of those cultures told its own story: a predominance of IgD-CD27- B cells, a subset that lacks the classical markers of activated memory cells and is generally associated with a less mature, less responsive state.

Crucially, the defect was not a simple absence of responsive cells. On day 6 of culture, the proportion of memory B cells in the patients’ cultures was comparable to that seen in healthy controls. This timing matters enormously for interpretation. It suggests that CVID B cells can initially be pushed toward a memory-like phenotype when stimulated through Toll-like receptors in the presence of IL-2, but that this apparent activation cannot be consolidated into durable antibody output. The failure, in other words, appears to lie in the later stages of the differentiation program, in the transition from an activated, memory-like state to a fully functional antibody-secreting plasma cell, rather than in the earliest steps of B-cell activation.

To probe the molecular roots of that failure, the researchers turned to transcriptomic analysis, sequencing the gene expression profiles of the cultured cells. The comparison between patients and healthy controls uncovered a coherent pattern of dysregulation. Genes related to antibody production were expressed at lower levels in the patients’ cells, consistent with the observed collapse in antibody secretion. Genes involved in adhesion and in proinflammatory signaling were also downregulated, pointing to a broader failure of the activated B cell to adopt the full behavioral repertoire of a responding immune cell, including the physical interactions with other immune cells that normally support germinal-center-like reactions in the culture dish.

Perhaps most intriguingly, the patients’ cells showed increased expression of genes associated with immune inhibitory responses. This shift toward an inhibitory program provides a mechanistic explanation for the paradox that has long defined CVID: B cells that are present, sometimes numerous, and capable of at least partial activation, yet chronically unable to deliver protective antibodies. If the cells are actively ramping up inhibitory pathways in response to stimulation, then the defect may not be a passive inability to respond but an active regulatory brake, one that engages precisely when the cells should be committing to antibody production.

The analysis of soluble factors in the culture supernatants reinforced this picture. Compared with healthy controls, the patients’ cultures contained lower concentrations of APRIL, a cytokine that plays a well-established role in supporting B-cell survival and the differentiation of antibody-secreting cells, and lower levels of interferon-alpha, an antiviral cytokine with important immunoregulatory functions. At the same time, the patients’ supernatants showed higher concentrations of BTLA, an inhibitory receptor of the CD28 family that delivers dampening signals to lymphocytes. The combination is telling: the patients’ cultures were simultaneously deprived of positive differentiation signals and enriched for inhibitory ones, a molecular environment stacked against sustained antibody output.

Taken together, the study’s findings sketch a coherent model of B-cell dysfunction in CVID. When stimulated through Toll-like receptors, the cells of these patients can begin the journey toward activation and memory differentiation, but they cannot sustain it. Their gene expression programs drift away from antibody production, adhesion, and inflammation and toward immune inhibition, while their soluble environment loses the supportive cytokines that healthy cultures provide. The researchers suggest that these insights into functional impairment after Toll-like receptor stimulation may be directly relevant to the B-cell dysfunction observed in patients with CVID, and they may help explain why some patients show only partial responses to vaccines that depend heavily on this signaling pathway.

The work also carries practical implications for the future. An in vitro assay that reliably distinguishes the functional profile of CVID B cells from healthy ones could, with further validation, help stratify patients, identify those with residual responsiveness, and guide more individualized approaches to immunoglobulin replacement and vaccination strategies. The study was approved by the Institutional Ethics Committee of Hospital Universitario 12 de Octubre and conducted with written informed consent from all participants, whose willingness to donate blood samples the authors explicitly acknowledged. Funded through Spanish COVID-19 research projects and supported by the genomic analysis group of the Spanish National Cancer Research Centre, the research exemplifies how translational immunology can turn a bedside mystery, why vaccinated patients remain vulnerable, into a bench-side mechanism, one inhibitory signal at a time.

Subject of Research: B-cell functional impairment in common variable immunodeficiency assessed by in vitro Toll-like receptor stimulation

Article Title: Common variable immunodeficiency: B cells' impairment in an in vitro assay

Article References: Arroyo-Sánchez, D., Chivite-Lacaba, M., González-Cuadrado, C., Almendro-Vázquez, P., Bermejo Olivera, F. J., Andara-Cordero, L. A., Garcinuño, S., Velasco-Sidro, M., Nieto-López, C., Alfocea Molina, Á., Cantonad Ruigómez, C., Pascual Palacios, L., Pleguezuelo-Garrote, D. E., Paz-Artal, E., & Cabrera-Marante, O. (2026). Common variable immunodeficiency: B cells' impairment in an in vitro assay. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-08821-8

Image Credits: AI Generated

DOI: 10.1186/s12967-026-08821-8

Keywords: common variable immunodeficiency, B cells, antibody production, Toll-like receptor, R848, interleukin-2, transcriptomics, ELISPOT, flow cytometry, APRIL, BTLA, primary immunodeficiency

The study, led by Ahmad Al Khleifat and Ammar Al-Chalabi of King’s College London together with collaborators across the United Kingdom and France, examined data from MIROCALS, a phase 2b randomised, double-blind, placebo-controlled trial of low-dose interleukin-2 in ALS. That trial, which enrolled 220 participants, had previously produced a striking finding: the concentration of phosphorylated neurofilament heavy chain, or pNFH, in the cerebrospinal fluid was not only a powerful predictor of survival in its own right, but also modified the treatment effect of the immunomodulatory drug. In other words, the amount of this protein, which leaks into the fluid surrounding the brain and spinal cord when axons are damaged, told researchers which patients were likely to respond to the therapy. The question the new analysis posed was whether a purely clinical tool, the TRICALS risk score, could do the same job without the need for an invasive lumbar puncture.

The TRICALS survival prediction model is an impressive piece of clinical epidemiology in its own right. Derived from more than 10,000 individuals across international cohorts, it combines age, the delay between symptom onset and diagnosis, scores on the revised ALS Functional Rating Scale, the site of disease onset, and respiratory status into a single validated index that robustly predicts how long a patient is likely to live. Because it requires nothing more than routine clinical assessment, it is cheap, quick, and easy to apply in any trial centre in the world. If it could replace a molecular biomarker, trial designers could streamline their statistical models considerably, avoiding the complexity and cost of collecting and assaying cerebrospinal fluid samples. That possibility is what made the new analysis worth doing.

The researchers designed two prespecified comparisons. In the first, the substitution analysis, they took the published MIROCALS biomarker model, which included the functional rating score, age, regulatory T-cell frequency, plasma CCL2, cerebrospinal fluid pNFH, treatment arm, and a pNFH-by-treatment interaction, and simply swapped the neurofilament measurement for the TRICALS risk score. In the second, the augmentation analysis, they kept the full biomarker model intact and added the TRICALS score on top, testing whether the clinical phenotype contributed anything beyond what the molecular marker already captured. Model performance was judged using likelihood ratio statistics and the negative two log likelihood, standard measures of how well a statistical model describes the observed survival data.

The results of the substitution analysis were unambiguous. Replacing pNFH with the TRICALS score caused model performance to deteriorate sharply, with the negative two log likelihood rising from 793.36 in the published biomarker model to 928.25 under the substituted specification. The TRICALS score did interact significantly with treatment, yielding a hazard ratio of 0.72 with a 95 percent confidence interval of 0.54 to 0.96 and a p value of 0.025, which means a treatment effect would still have been detected. But the contribution of that interaction to overall model fit was modest, adding a change in the chi-squared statistic of only 4.76, compared with 14.24 for the pNFH-by-treatment interaction in the original model. The clinical score captured some of the treatment-response signal, but only a fraction of it.

The correlation analysis explained why. The TRICALS risk score and cerebrospinal fluid pNFH were only moderately correlated, with a Pearson coefficient of 0.357 across the 220 participants. The coefficient of determination, the square of that value, comes to just 0.127, meaning the clinical score accounts for roughly 12.7 percent of the variance in the neurofilament concentration. The remaining 87 percent reflects biology that the clinical assessment simply cannot see. Neurofilament levels track the ongoing destruction of motor axons at a molecular level, a process that unfolds at different rates in different patients and is only loosely reflected in how quickly their symptoms have progressed so far. Two patients with identical age, onset site, functional scores, and diagnostic delay can carry very different burdens of active neurodegeneration, and it is that burden, rather than the clinical phenotype, that appears to govern response to the immune-targeting therapy.

The augmentation analysis told the complementary story. When cerebrospinal fluid pNFH and its interaction with treatment were added to the TRICALS-based model, the fit improved substantially, with a change in chi-squared of 14.24 and a p value below 0.001. The interaction term itself was highly significant, and once it entered the model, the treatment effect became robust, with a hazard ratio of 0.28 and a 95 percent confidence interval of 0.12 to 0.63, a p value of 0.002. Notably, both the TRICALS score and pNFH remained independently associated with survival in the combined model, indicating that each variable carried information the other did not. The final framework simultaneously captured baseline clinical severity, biological disease activity, and the heterogeneity of treatment response, three dimensions that no single measure could encompass alone.

The authors are careful to acknowledge the limitations of their work. This was a post-hoc analysis of an existing trial dataset rather than a formal reanalysis, designed specifically to test whether a phenotypic score could substitute for a fluid biomarker of neurodegeneration. The complete-case approach, the relatively modest sample size of 220 participants, and the focus on a single immunomodulatory intervention all constrain how far the conclusions can be generalised. Yet the biological logic of the finding is compelling, and it aligns with a growing body of evidence linking neurofilament concentrations to the rate and extent of neuroaxonal degeneration in ALS. The study was conducted in compliance with Good Clinical Practice and the Declaration of Helsinki, with all analyses performed on fully anonymised data under the trial’s data-sharing agreements.

The implications for trial design are immediate and practical. Composite clinical risk scores remain valuable for adjusting for baseline differences between treatment groups, and the new results confirm that they do carry some information about treatment-response heterogeneity. But they should not be treated as surrogates for molecular stratification. As ALS therapies increasingly target specific biological pathways, from immune modulation and protein aggregation to RNA metabolism and mitochondrial dysfunction, no single biomarker is likely to serve every trial. Instead, the authors argue, optimal design will require identifying molecular markers that directly index the biological process each intervention is meant to hit. For an immune-targeting drug like low-dose interleukin-2, the burden of neuroaxonal injury, read out through pNFH, proved to be that marker.

The broader message is a pragmatic blueprint for precision medicine in neurodegenerative disease. Clinical phenotype should anchor baseline risk adjustment; disease-activity biomarkers such as neurofilaments should identify the patients most likely to respond; and integrating both within a unified survival modelling framework offers mechanistic insight, statistical efficiency, and a clearer path to interpretable, therapeutically informative trials. For a disease that has defeated dozens of experimental therapies over three decades, the lesson is sobering but constructive: the shortcuts that seem most convenient, the clinical scores that require no needle and no laboratory, are precisely the ones that cannot carry the full weight of prediction. The biology, inconvenient as it may be, must be measured directly.

Subject of Research: Comparison of the TRICALS clinical risk score and cerebrospinal fluid neurofilament biomarkers for prognosis and treatment stratification in amyotrophic lateral sclerosis trials

Article Title: TRICALS risk score augments but cannot replace neurofilament as a prognostic biomarker in ALS

Article References: Al Khleifat, A., Malaspina, A., Kirby, J., Tree, T., Shaw, P. J., Leigh, P. N., & Al-Chalabi, A. (2026). TRICALS risk score augments but cannot replace neurofilament as a prognostic biomarker in ALS. Journal of Neurology, 273(10), Article 643. https://doi.org/10.1007/s00415-026-14040-4

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14040-4

Keywords: amyotrophic lateral sclerosis, ALS, TRICALS risk score, neurofilament, pNFH, biomarkers, clinical trials, MIROCALS, interleukin-2, prognosis, precision medicine, neurodegeneration

To understand why the CAR-Treg idea is so compelling, it helps to start with the biology of regulatory T cells themselves. Tregs are a specialized subset of CD4-positive T lymphocytes defined by expression of the transcription factor FOXP3, high levels of the interleukin-2 receptor alpha chain CD25, and low levels of CD127. Their job is to restrain immune responses that would otherwise damage self-tissues. They do this through several complementary mechanisms: secreting anti-inflammatory cytokines such as interleukin-10 and transforming growth factor beta, consuming local interleukin-2 to starve effector T cells, expressing CTLA-4 to strip costimulatory signals from antigen-presenting cells, and releasing granzyme-bearing cytotoxic granules. The integrity of this lineage is tracked molecularly by the Treg-specific demethylated region, or TSDR, a stable epigenetic mark at the FOXP3 locus that distinguishes genuinely stable suppressive cells from unstable, inflammation-induced FOXP3 expressers. When this system fails, either in number or in function, autoimmunity follows, and vasculitis is a prime example of that failure playing out in the vessel wall.

The review systematically assembles the human evidence for Treg dysfunction across the vasculitis spectrum, and the picture that emerges is consistent in direction, if variable in detail. In antineutrophil cytoplasmic antibody-associated vasculitis, or AAV, which includes granulomatosis with polyangiitis and microscopic polyangiitis, patients show reduced circulating Treg frequencies and impaired suppressive capacity, particularly during active disease. The autoantigens in AAV are well defined: myeloperoxidase and proteinase 3, enzymes normally confined to neutrophil granules that become aberrantly displayed on the cell surface and, in genetically susceptible individuals, trigger autoreactive T and B cell responses. In giant cell arteritis and Takayasu arteritis, the large-vessel diseases, Treg abnormalities coexist with a pro-inflammatory Th1 and Th17 milieu that drives granulomatous inflammation of the arterial wall. The authors are careful to grade this evidence, distinguishing direct findings in vasculitis patients from mechanistic work in other autoimmune diseases such as systemic lupus erythematosus and type 1 diabetes, and from untested therapeutic hypotheses. That discipline matters, because the field has repeatedly seen promising immunological correlations fail to translate into clinical benefit.

Against that backdrop, the review evaluates three escalating therapeutic strategies. The first is endogenous Treg expansion, most prominently through low-dose interleukin-2. Because Tregs are exquisitely sensitive to interleukin-2 through their high-affinity CD25-containing receptor, low-dose regimens preferentially activate the STAT5 signaling pathway in Tregs, promoting their survival, proliferation and suppressive function without broadly stimulating conventional T cells. Early human studies in vasculitis provide limited but genuine support for this approach, with signals of biological activity and tolerability. The second strategy is polyclonal Treg transfer, in which Tregs are expanded ex vivo from a patient or donor and reinfused without any antigen specificity. This approach has the advantage of manufacturing simplicity but the disadvantage of diffuse, antigen-agnostic suppression, which may blunt protective immunity and may not concentrate suppressive activity where it is needed: at the inflamed vessel wall.

The third and most technologically ambitious strategy is the antigen-specific engineered Treg, and here the review dives deep into the engineering itself. A CAR-Treg is created by introducing a synthetic receptor into Tregs that combines an extracellular single-chain variable fragment, or scFv, which binds a target antigen directly and HLA-independently, with intracellular signaling domains. First-generation constructs used only CD3-zeta, while second-generation designs add costimulatory modules such as CD28 or 4-1BB, which shape the cells’ metabolic fitness, proliferative capacity and stability. For Tregs specifically, the choice of signaling domain is not trivial: CD28-based signaling can support FOXP3 stability, whereas 4-1BB-based signaling biases cells toward a more oxidative metabolic profile. The goal is a cell that homes to the site of vascular inflammation, recognizes its target with precision, and delivers localized immunosuppression without systemic immune paralysis. Proposed targets in vasculitis include activated endothelium, marked by molecules such as ICAM-1 and VCAM-1, and the autoreactive responses directed against myeloperoxidase and proteinase 3.

Here the review delivers its most important caveat. Those proposed targets, the authors emphasize, remain design hypotheses. No published study has yet validated a CAR-Treg construct against activated endothelium or against MPO- or PR3-specific autoreactivity in a vasculitis-relevant model, let alone in a patient. The distinction between a plausible target and a validated one is where many cell therapy programs have stumbled. Endothelial targets such as ICAM-1 are expressed not only at sites of vasculitic inflammation but also in ordinary physiological immune responses, raising the specter of off-target suppression of useful immunity. Antigen-specific approaches targeting MPO or PR3 face a different problem: the relevant autoantigens are presented by human leukocyte antigen molecules, which means a truly antigen-specific strategy may need to engage the peptide-HLA complex rather than a bare protein, pushing the design toward T cell receptor-engineered Tregs, or TCR-Tregs, rather than scFv-based CARs. TCR-Tregs offer HLA-restricted, peptide-level specificity, but their manufacture is more complex and their activity depends on the patient’s HLA type, complicating product development.

The review does not treat CAR-Tregs in isolation. It systematically compares them with the competing tolerogenic platforms now in development. TCR-engineered Tregs, as noted, offer fine antigen specificity at the cost of HLA dependence. Tolerogenic dendritic cells, which present antigen in a context that induces rather than breaks tolerance, represent a cell-based vaccination strategy. Treg-biased interleukin-2 agents, including engineered IL-2 muteins and antibody-IL-2 fusion complexes, aim to expand the patient’s own regulatory compartment without ex vivo manipulation. Antigen-specific tolerizing platforms, including nanoparticle-based delivery of self-antigens, seek to re-educate the immune system at the level of antigen presentation. Each platform occupies a different point on the trade-off curve between specificity, manufacturing complexity, and breadth of effect. CAR-Tregs sit at the high-specificity, high-complexity end, which is precisely why the authors insist that translation must be staged rather than rushed.

Manufacturing and safety form another major pillar of the analysis. CAR-Treg production must satisfy good manufacturing practice standards, and the field lacks standardized product-release criteria: what combination of FOXP3 expression, TSDR demethylation, suppressive potency and phenotype purity defines a releasable lot remains unsettled. Safety concerns differ from those of conventional CAR-T cells. Because Tregs are inherently suppressive rather than cytotoxic, the dramatic toxicities seen with CAR-T cancer therapy, cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, are expected to be less frequent. But CAR-Tregs carry their own risks: off-target or on-target suppression of protective immunity, infection susceptibility, the possibility that engineered cells lose FOXP3 expression and acquire inflammatory functions under inflammatory conditions, and the long-term uncertainty of any living drug. The review also highlights trajectory control technologies, such as synthetic Notch receptors and logic-gated constructs, that could restrict Treg activation to precise antigen combinations, as well as homing engineering through chemokine receptors like CCR4, CCR9, CXCR3 and CXCR5, and the gut-homing integrin alpha-4-beta-7, to steer cells to inflamed vascular beds.

The regulatory and implementation landscape receives equally sober treatment. Early-phase trials will need carefully selected cohorts, probably patients with active disease and measurable biomarkers such as the Birmingham Vasculitis Activity Score, with long-term safety follow-up built into the protocol from the start. The authors argue for a staged pathway: first validate targets in human tissue and disease-relevant models, then establish standardized manufacturing and release criteria, then proceed to small, biomarker-rich early-phase studies before any consideration of broader deployment. They also acknowledge, transparently, that the review itself used generative AI tools for literature search and language editing, with the authors verifying all content and taking full responsibility for the conclusions, a detail that reflects the evolving norms of contemporary translational science.

The significance of this review lies less in announcing a breakthrough than in drawing an honest map. The immunological rationale for precision tolerance in vasculitis is real: Treg abnormalities are documented in human disease, and the tools of cellular engineering have matured dramatically since CAR-T cells transformed oncology. But the review’s central message is that CAR-Tregs for vasculitis are a hypothesis with a defined testing program, not a therapy on the shelf. If the proposed targets survive validation, if manufacturing can deliver stable, potent, correctly homing cells, and if early trials are designed with the rigor the authors demand, antigen-specific CAR-Tregs could one day offer vasculitis patients something no current drug provides: durable, antigen-specific restoration of immune tolerance without chronic immunosuppression. Until then, the field’s most valuable asset is exactly the kind of disciplined, evidence-graded analysis this review provides, separating what human data actually show from what the field hopes might one day be possible.

Subject of Research: Regulatory T cell dysfunction in vasculitis and the translational development of antigen-specific CAR-Treg therapy for immune tolerance restoration

Article Title: Precision tolerance in vasculitis: from Treg dysfunction to antigen-specific CAR-Treg therapy

Article References: Liu, Z., Wang, S., Li, X., Zhang, J., Li, J., Liu, Y., Wang, Y., & Lv, H. (2026). Precision tolerance in vasculitis: from Treg dysfunction to antigen-specific CAR-Treg therapy. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-08956-8

Image Credits: AI Generated

DOI: 10.1186/s12967-026-08956-8

Keywords: vasculitis, regulatory T cells, CAR-Tregs, immune tolerance, autoimmune disease, precision immunotherapy, interleukin-2, ANCA-associated vasculitis, cell therapy, FOXP3, translational medicine, endothelium

The central problem the researchers set out to solve is well known to anyone following the CAR-T field. Engineered T cells have produced remarkable results in certain blood cancers, but solid tumors present a hostile microenvironment that wears these cells down. In pancreatic cancer specifically, mesothelin-targeted CAR-T therapy—a promising approach because mesothelin is abundantly expressed on pancreatic tumor cells—has been limited by insufficient persistence, progressive T-cell exhaustion, and metabolic dysfunction. CAR-T cells that enter the tumor find themselves starved of nutrients, bathed in suppressive signals, and deprived of the cytokine support they need to keep proliferating and killing. Within days, many of them become dysfunctional ghosts of their former selves.

Interleukin-2 is the classic T-cell growth cytokine, and systemic administration of recombinant IL-2 has long been known to boost T-cell responses. But giving IL-2 intravenously at doses high enough to support CAR-T cells triggers severe toxicity, including vascular leak syndrome and dangerous expansion of regulatory T cells, which paradoxically suppress antitumor immunity. The study’s solution is elegant in its localization: the team engineered second-generation MSLN-targeted CAR-T cells to secrete an IgG1 Fc-fused IL-2(C125S) variant, creating what they call MSLN-IL2m CAR-T cells. The Fc fusion extends the cytokine’s half-life, while the C125S mutation disables a site associated with preferential expansion of regulatory T cells, aiming the growth signal preferentially at the CAR-T cells themselves rather than at their suppressive counterparts.

The experimental design was deliberately rigorous. The researchers generated CAR-T cells from five independent healthy donors, ensuring that their findings were not an artifact of a single donor’s immune system. They tested these cells against pancreatic ductal adenocarcinoma cell lines expressing different levels of mesothelin, subjected them to serial antigen-stimulation assays that mimic the repeated encounters CAR-T cells face inside a tumor, and challenged them with suppressive-stress models designed to reproduce the hostile conditions of the pancreatic tumor microenvironment. Phenotypic and functional analyses tracked exhaustion markers and memory phenotypes, while metabolic-flux assays measured the cells’ mitochondrial performance in real time.

The results were striking across the board. MSLN-IL2m CAR-T cells showed enhanced expansion and stronger activation of STAT5, the transcription factor that serves as the primary downstream messenger for the IL-2 receptor, while maintaining CAR expression and viability comparable to conventional cells. When repeatedly stimulated with antigen, the cytokine-secreting cells demonstrated stronger antigen-dependent cytotoxicity, greater proliferation, more robust cytokine production, and markedly better functional persistence. Just as importantly, they displayed reduced expression of exhaustion-associated markers and preserved memory-associated phenotypes—the immunological hallmarks of cells that can keep fighting rather than burn out.

The metabolic findings may be the most novel aspect of the study. Under PDAC-associated suppressive conditions, MSLN-IL2m CAR-T cells maintained greater mitochondrial membrane potential, greater spare respiratory capacity, and higher ATP production than their conventional counterparts. They also expressed higher levels of PPARGC1A, the master regulator of mitochondrial biogenesis, and CPT1A, a key enzyme in fatty acid oxidation, while showing a lower mitochondrial superoxide-associated signal, indicating less oxidative damage. In the metabolic language of modern immunology, these cells remained oxidative, resilient powerhouses instead of collapsing into the glycolytically exhausted state that characterizes dysfunctional tumor-infiltrating T cells.

To confirm that these advantages actually flowed through the IL-2 receptor pathway, the researchers used pharmacological STAT5 inhibition and IL-2Rα blockade. Both interventions partially attenuated the functional, phenotypic, and metabolic advantages of the engineered cells, supporting an important—but notably non-exclusive—contribution of IL-2Rα–STAT5 signaling. This partial dependence suggests that the Fc-fused cytokine may also act through additional mechanisms, such as autocrine and paracrine effects on other IL-2 receptor configurations, and leaves room for further mechanistic dissection in future work.

The in vivo results provided the crucial translational validation. In an AsPC-1 xenograft model of pancreatic cancer, MSLN-IL2m CAR-T cells showed greater intratumoral accumulation, improved tumor control, and reduced bioluminescent tumor burden compared with conventional MSLN CAR-T cells, and the treated animals survived significantly longer. Tolerability assessments revealed no major abnormalities in hepatic, renal, or hematologic parameters, and body weight remained stable—early reassurance that localized cytokine delivery does not reproduce the systemic toxicity that has plagued recombinant IL-2 therapy, though the authors are careful to note that comprehensive safety evaluation remains necessary.

The implications for the field are considerable. Armoring CAR-T cells with autocrine cytokine support has been attempted before, but the specific combination of an Fc fusion for extended half-life and the C125S mutation for reduced regulatory T-cell preference represents a refined iteration of the concept. By coupling the cytokine’s production directly to the CAR-T cells themselves, the approach ensures that the growth signal is delivered exactly where it is needed—at the tumor site, in the midst of antigen stimulation—rather than systemically. The metabolic data add an important dimension, suggesting that the cytokine support does not merely keep cells alive but actively preserves their mitochondrial machinery and oxidative metabolism under stress.

Cautions remain, as they must in any preclinical study. The xenograft model used, while standard for the field, does not fully recapitulate the immunosuppressive complexity of human pancreatic tumors, and the authors explicitly call for validation in clinically relevant models and comprehensive safety assessment before the approach moves toward patients. Questions about the long-term behavior of cytokine-secreting cells, the risk of uncontrolled autonomous growth, and the behavior of the construct in humans all await answers. Still, the study delivers a clear and encouraging message: when CAR-T cells are engineered to carry their own metabolic and survival support into the tumor battlefield, they fight longer, stay fitter, and kill better—a combination that pancreatic cancer patients, who have waited too long for immunotherapy to work for them, will be watching closely.

Subject of Research: Engineering mesothelin-targeted CAR-T cells to secrete Fc-fused IL-2(C125S) to improve persistence and antitumor activity in pancreatic cancer

Article Title: Fc-fused IL-2(C125S) improves MSLN-targeted CAR-T cell persistence, metabolic fitness, and antitumor activity

Article References: Quan, H., Yao, J., Zhang, Y., Zhan, F., & Wang, Y. (2026). Fc-fused IL-2(C125S) improves MSLN-targeted CAR-T cell persistence, metabolic fitness, and antitumor activity. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-09016-x

Image Credits: AI Generated

DOI: 10.1186/s12967-026-09016-x

Keywords: CAR-T cells, pancreatic ductal adenocarcinoma, mesothelin, interleukin-2, T-cell exhaustion, mitochondrial fitness, immunometabolism, STAT5 signaling, solid tumors, cytokine delivery, preclinical study, Journal of Translational Medicine

The clinical foundation of TIL therapy rests on a deceptively simple concept. Tumor-infiltrating lymphocytes, primarily cytotoxic CD8-positive T cells and helper CD4-positive T cells, migrate from peripheral blood into the tumor microenvironment, where they recognize and attack malignant cells through direct cytotoxicity. Adoptive cell therapy with autologous TILs amplifies this natural response: tumor-resident T cells are isolated from excised tumor tissue, expanded to billions in the laboratory, and returned to the patient after a non-myeloablative lymphodepleting chemotherapy regimen designed to clear immunosuppressive cells and cytokine sinks. The protocol that underpins most current regimens, including the FDA-approved product lifileucel, traces directly to the pioneering work of Steven Rosenberg’s laboratory at the U.S. National Cancer Institute, with only minor modifications accumulated over decades.

The clinical evidence base is now substantial. In 2024, the U.S. Food and Drug Administration approved lifileucel as the first autologous TIL product for patients with advanced cutaneous melanoma, a landmark moment for the field. A meta-analysis of 13 studies employing high-dose interleukin-2 in TIL therapy, encompassing 617 patients with advanced cutaneous melanoma including some with brain metastases, reported an objective response rate of 34 percent among patients previously treated with anti-PD-(L)1 agents and 44 percent among those without such prior treatment. Notably, the analysis found no statistically significant difference in objective response or complete response rates between the two groups, suggesting that interleukin-2’s immunomodulatory effects allow TIL therapy to retain benefit even after checkpoint inhibitor failure. Recent studies of patients refractory to immune checkpoint inhibitors or targeted therapies have shown objective response rates of 28 to 49 percent in melanoma resistant to standard treatments.

The reach of TIL therapy now extends well beyond melanoma. In non-small cell lung cancer, the IOV-COM-202 trial tested lifileucel in two cohorts following the same nonmyeloablative lymphodepletion regimen of cyclophosphamide and fludarabine, a single TIL infusion, and up to six doses of high-dose interleukin-2. Cohort 3B, comprising 28 patients with immunosuppressant-resistant metastatic disease, achieved an objective response rate of 21.4 percent after a median follow-up of 16 months. Cohort 3A, in checkpoint inhibitor-naive patients receiving pembrolizumab before lymphodepletion, showed a striking 64.3 percent objective response rate in the EGFR-wildtype subgroup at a median follow-up of 25.6 months. In cervical cancer, a National Cancer Institute phase 2 trial of 18 patients with HPV16- or HPV18-positive disease reported a 28 percent response rate, including two durable complete responses lasting 67 and 53 months, while a multicenter study by Iovance Biotherapeutics in checkpoint-naive advanced cervical cancer achieved a 44 percent objective response rate among 27 patients. Meta-analytic estimates suggest objective response rates of up to 26.3 percent across gynecologic cancers, and early signals of activity have emerged in colorectal cancer, cholangiocarcinoma, breast cancer, head and neck squamous cell carcinoma, and pancreatic ductal adenocarcinoma.

Understanding why interleukin-2 is both indispensable and hazardous requires a look at its receptor biology. The interleukin-2 receptor is a heterotrimeric protein composed of alpha (CD25), beta (CD122) and gamma (CD132) subunits, whose variable expression across immune cell types produces the cytokine’s diverse functional effects. Preclinical work has established the beneficial face of interleukin-2 signaling. Trentin and colleagues, studying TILs from 16 patients with solid tumors, demonstrated that interleukin-2 signaling through CD122 and CD25 promotes TIL proliferation and functional activation, marked by increased activity in the JAK/STAT pathway. Interleukin-2 also enhances cytotoxic function by boosting secretion of interferon-gamma and tumor necrosis factor-alpha, cytokines that directly inhibit tumor growth. In one in vitro study, interleukin-2 exposure led to downregulation of PD-1 on CD8-positive tumor-specific TILs, hinting at a mechanism for potentiating anti-tumor activity. The historical arc began in 1986, when Rosenberg’s group showed in murine models that interleukin-2 supplementation improves TIL efficacy, and culminated in a 1988 clinical trial combining TIL therapy with high-dose interleukin-2 that achieved a 60 percent objective response rate in previously untreated advanced melanoma patients. The standard regimen that followed, delivering at least 720,000 international units per kilogram intravenously every eight hours until dose-limiting toxicity or tolerance, has anchored metastatic melanoma treatment for more than 30 years.

The adverse face of interleukin-2, however, is impossible to ignore. In a clinical study of 391 patients, 87 percent experienced hypotension and 73 percent developed vascular leak syndrome or edema after high-dose treatment. Activation of CD25 on endothelial cells appears to contribute to these effects. Vascular leak syndrome induces hypovolemia that cascades into multi-organ dysfunction affecting the heart, kidneys, gastrointestinal tract and brain, producing reduced perfusion, ischemia, oliguria and neurological symptoms including confusion. In the pulmonary vasculature it can cause congestion and dyspnea, with severity increasing under continuous interleukin-2 therapy. The black box warning for high-dose interleukin-2 mandates intensive care monitoring due to the risk of acute kidney injury from renal hypoperfusion and cytokine-mediated neurotoxicity. Lifileucel, despite its efficacy, carries a treatment-related mortality rate of 7.5 percent, and its label restricts administration to trained clinicians at specialized facilities. The trial record is sobering: Creelan and colleagues reported two early deaths in patients with anti-PD-1-resistant metastatic lung cancer linked to rapidly progressive disease combined with the physiological stress of lymphodepletion and interleukin-2, and the IOV-LUN-202 trial in advanced non-small cell lung cancer was halted by the FDA in December 2023 following a treatment-related death.

Perhaps the most provocative findings concern interleukin-2’s subtler immunological sabotage. Work by Liu and colleagues and recent single-cell analyses show that interleukin-2 drives exhaustion of tumor-reactive CD8-positive T cells. In the absence of CD3/CD28 co-stimulation, interleukin-2 alone does not impair cytokine production but increases expression of the inhibitory receptors PD-1, LAG-3 and TIM-3. Prolonged high-dose exposure causes sustained STAT5 activation, which increases tryptophan hydroxylase-1 activity and enhances inhibitory receptor signaling, progressively degrading cytokine and effector molecule production. Single-cell transcriptomic and epigenetic studies trace the full exhaustion trajectory: prolonged interleukin-2 signaling pushes T cells from progenitor-like to terminally exhausted subsets, sequentially activating exhaustion-associated transcriptional programs such as TOX and NR4A while eroding memory-related gene expression. The tumor microenvironment compounds the problem, as hypoxia, nutrient competition, and immunosuppressive factors like TGF-beta and prostaglandin E2 interact with interleukin-2 to reinforce exhaustion-associated epigenetic programs. High CD25 expression also gives regulatory T cells a competitive advantage in capturing interleukin-2, allowing them to outcompete cytotoxic T cells and suppress the anti-tumor response, which in turn necessitates intensive lymphodepletion with its own toxicities.

The search for interleukin-2-independent TIL therapy has therefore become the field’s most active frontier. The clearest clinical success to date is GC101, developed by Shanghai Juncell Therapeutics as the first reported TIL therapy that eliminates post-infusion interleukin-2 altogether. GC101 is cultured in a pre-rapid expansion protocol medium containing interleukin-2, interleukin-7 and interleukin-15, followed by expansion with low-dose interleukin-2 at 300 international units per milliliter, allowing the final product to function without exogenous interleukin-2 after transfer. It uses a three-day lymphodepletion regimen of cyclophosphamide with hydroxychloroquine, and in phase 1 trials involving 14 evaluable patients with advanced gynecologic cancers achieved a 36 percent objective response rate, including complete remission in a patient with recurrent cervical cancer. Critically, GC101 can be administered entirely in general wards rather than intensive care units, improving safety and reducing costs. It has now advanced to a pivotal phase 2 randomized controlled trial in melanoma. Genetic engineering offers a parallel route: GC203, engineered to constitutively express membrane-bound interleukin-7, showed no grade 3 or higher non-hematologic adverse events in the first 18 ovarian cancer patients treated, while OBX-115 from Obsidian Therapeutics, expressing regulated membrane-bound interleukin-15, demonstrated in preliminary data from 10 patients an improved safety profile with no grade 4 or higher and only limited grade 3 non-hematologic events. Earlier attempts carry cautionary lessons, however: TILs engineered to secrete interleukin-12 achieved a 63 percent response rate in a 2015 first-in-human study but the trial was terminated early after life-threatening hemodynamic instability from interleukin-12 toxicity. CRISPR-based approaches are also emerging, with KSQ Therapeutics knocking out SOCS1 and Regnase-1 to enhance T cell activation, now in ongoing clinical trials.

The review’s authors are careful to separate proof-of-concept promise from validated clinical reality. Current engineered TIL evidence rests on small patient numbers, lacks randomized controlled trials, and involves short follow-up, while personalized genetic modification imposes stringent quality control demands and high production costs that limit scalability. Potential risks of sustained cytokine expression and CRISPR off-target effects demand careful trial design and long-term monitoring. Still, the strategic direction is clear. In the near term, the authors argue for predictive biomarkers incorporating T-cell exhaustion signatures, stem-like progenitor frequency and tumor microenvironment features to guide patient selection, alongside comparative studies to refine lymphodepletion regimens. Looking ahead, they call for next-generation interleukin-2 analogs that selectively stimulate effector T cells while sparing regulatory T cells, electroporation-based engineering as a safer alternative to viral vectors, and combination strategies with checkpoint inhibitors, targeted therapies or oncolytic viruses. If the field succeeds on both fronts, biologically precise interleukin-2-independent engineering and scalable, cost-effective manufacturing, TIL therapy could establish itself as a cornerstone of precision oncology for treatment-refractory solid tumors, finally resolving the paradox that interleukin-2 has imposed on cancer immunotherapy for nearly forty years.

Subject of Research: The dual role of interleukin-2 in tumor-infiltrating lymphocyte therapy for solid tumors

Article Title: Dual role of interleukin-2 in tumor-infiltrating lymphocyte therapy

Article References: Lu, L., Zhuang, W., Li, W., Huang, C., Xiao, S., Zhang, S., Lu, Z., Bai, J., Pang, Z., Jin, H., Zhou, Y., & Gu, J. (2026). Dual role of interleukin-2 in tumor-infiltrating lymphocyte therapy. Clinical Cancer Bulletin, 5(1), Article 7. https://doi.org/10.1007/s44272-026-00059-1

Image Credits: AI Generated

DOI: 10.1007/s44272-026-00059-1

Keywords: tumor-infiltrating lymphocytes, interleukin-2, TIL therapy, immunotherapy, solid tumors, lifileucel, melanoma, vascular leak syndrome, T cell exhaustion, engineered TIL, GC101, cancer immunotherapy

The strategy hinges on an engineered bifunctional fusion molecule called anti-TCRβ-IL-2, described in a study published in the Journal of Experimental & Clinical Cancer Research. The molecule has two business ends. One is a monovalent antibody fragment that binds the T-cell receptor, the molecular antenna that T cells use to recognize foreign or abnormal cells, at specific residues on its variable beta (Vβ) chain. The other end is interleukin-2, a powerful growth and activation signal for T cells. By physically coupling these two functions, the molecule delivers interleukin-2 selectively to T cells bearing particular TCRβ chains, rather than flooding the entire immune system with the cytokine, a limitation that has historically made IL-2 therapy toxic and poorly targeted.

Because the T-cell receptor’s variable beta chain defines a distinct clonal family of T cells, the drug acts as a selective activator: it stimulates a defined subset of the T-cell repertoire rather than every T cell it encounters. The researchers reasoned that this targeted activation could push exhausted or bystander antitumor T cells back into a functional state, priming them so that a subsequent dose of anti-PD-1 could lock in the revived response. Checkpoint blockade alone often fails precisely because the T cells it is meant to unleash are too depleted to exploit the removal of their molecular brakes.

To test that logic, the team used a panel of syngeneic murine cancer models spanning a spectrum of sensitivity to immune checkpoint inhibition, from relatively responsive tumors to those with pronounced resistance. In the resistant settings, anti-PD-1 alone did what it typically does in patients who do not benefit: it expanded pools of terminally exhausted CD8+ T cells without producing meaningful tumor control. But when the mice received anti-TCRβ-IL-2 first, followed by anti-PD-1, the picture changed dramatically. The combination produced robust anti-tumor efficacy, including complete tumor cures and long-term immune protection against rechallenge in several models that were otherwise refractory to checkpoint therapy.

The mechanistic story emerged from an unusually deep interrogation of the tumor microenvironment. Using flow cytometry, single-cell transcriptomics, and histological analysis of tumor-infiltrating lymphocytes, the investigators found that the sequential regimen increased proliferation and cytotoxic markers, such as granzyme B and interferon-gamma, in both CD8+ and CD4+ T cells within the tumors. At the same time, exhaustion markers on CD8+ T cells declined, and the proportion of immunosuppressive regulatory CD4+ T cells shrank. In other words, the combination did not merely add more T cells to the fight; it shifted the balance of the tumor immune landscape from suppression and dysfunction toward active cytotoxicity.

Perhaps the most striking finding involved the breadth of the immune response. After combination therapy, mice developed multifunctional T-cell responses against tumor-associated antigens and, critically, against neoantigens, the mutant peptides that arise from the cancer’s own genetic alterations. This expansion of antigen-specific reactivity is the immunological hallmark of epitope spreading: as therapy kills tumor cells and releases new antigens, the immune system diversifies its attack beyond the targets it originally recognized. The study observed a marked increase in the number of multifunctional neoantigen-specific T cells in mice receiving the dual activator followed by anti-PD-1, compared with either monotherapy, suggesting that the combination builds a broader and more resilient army against the tumor than checkpoint inhibition can achieve on its own.

The sequencing mattered. Anti-TCRβ-IL-2 followed by anti-PD-1, rather than the reverse order or either agent alone, delivered the strongest effects, consistent with a model in which selective T-cell activation first revives the antitumor fleet and checkpoint blockade then sustains the newly functional cells by removing PD-1-mediated inhibition. Single-cell profiling revealed shifts in the composition and differentiation state of tumor-infiltrating lymphocytes, including evidence of reduced terminal exhaustion and enhanced cytotoxic programming in the CD8+ compartment after the combination.

The clinical implications are immediate. Building on these preclinical results, the researchers announce plans for a clinical trial evaluating the anti-TCRβ-IL-2 agent, known as invikafusp alfa, in combination with anti-PD-1 antibody therapy in patients with immune checkpoint inhibitor-refractory non-small cell lung cancer and castration-resistant metastatic prostate cancer. Both indications represent large patient populations in which resistance to checkpoint blockade is common and better options are urgently needed. If the murine findings translate, the combination could convert a subset of non-responders into durable beneficiaries of immunotherapy.

The work was conducted under a Cooperative Research and Development Agreement between the National Cancer Institute and Marengo Therapeutics, with support from the NCI Intramural Research Program, and was carried out under approved animal care protocols. Several co-authors are employees of Marengo Therapeutics, which is developing the TCRβ-directed platform. The study was published open access, and the authors emphasize that the T-cell activation mechanism it describes, reviving T-cell function and driving epitope spreading, offers a general blueprint for sensitizing refractory tumors to immune checkpoint inhibition rather than a single-drug solution.

For a field grappling with the ceiling of checkpoint immunotherapy, the study reframes the problem: instead of trying to push exhausted T cells harder with blockade alone, it suggests first handing them a targeted activation signal tailored to their receptor, then removing the brakes. In the mouse models reported here, that one-two sequence turned checkpoint failure into long-lasting cures. Whether the same revival can be reproduced in patients with exhausted, treatment-resistant tumors will be the question the planned clinical trials are designed to answer.

Subject of Research: A TCR beta chain-directed selective dual T-cell activator combined with anti-PD-1 to overcome immune checkpoint inhibitor resistance

Article Title: Overcoming immune checkpoint inhibitor-mediated T-cell exhaustion with a TCR β chain-directed selective dual T-cell activator

Article References: Angstadt, S., Horn, L. A., Fousek, K., Rajabian, N., Qin, H., Medina-Enriquez, M. M., Kelly, M. D., Hsiao-Sanchez, N., Meyer, T. J., Moisan, J., Katragadda, M., Bayliffe, A., Su, Z., Schlom, J., & Palena, C. (2026). Overcoming immune checkpoint inhibitor-mediated T-cell exhaustion with a TCR β chain-directed selective dual T-cell activator. Journal of Experimental & Clinical Cancer Research. https://doi.org/10.1186/s13046-026-03815-2

Image Credits: AI Generated

DOI: 10.1186/s13046-026-03815-2

Keywords: immune checkpoint inhibitors, T-cell exhaustion, anti-TCRβ-IL-2, PD-1, T-cell receptor, interleukin-2, epitope spreading, neoantigens, tumor microenvironment, invikafusp alfa, immunotherapy resistance, cancer immunotherapy

The team, led by co-first authors Judith Verdonk and Leila-Sophie Otten under the supervision of pharmacist Rob ter Heine, focused on non-small cell lung cancer, the setting in which pembrolizumab is most commonly used. Three approved dosing regimens were compared in silico: 2 milligrams per kilogram every three weeks, a flat 200 milligrams every three weeks, and a flat 400 milligrams every six weeks. These regimens were established through modelling and simulation during drug development, but the authors argue that the pharmacodynamic surrogate underpinning them, peripheral receptor occupancy, has never been rigorously validated as a predictor of clinical benefit.

To build their model, the researchers started from a physiological pharmacokinetic framework describing how pembrolizumab moves through plasma and penetrates tumour tissue. Antibody tumour penetration is a notoriously inefficient process, governed by convective transport, diffusion and antigen-mediated binding that can slow or even reverse the movement of drug into tumour interstitium. The model accounted for these dynamics, extending earlier work on antibody tumour transport, and then added two crucial layers: receptor occupancy kinetics and the induction of interleukin-2, a cytokine whose production reflects genuine T cell activation rather than mere receptor blockade.

The interleukin-2 parameters were not invented from thin air. They were derived from ex vivo experiments in which patient T cells were exposed to pembrolizumab and their functional responses measured. This experimental grounding matters, because an earlier study by the same group had already revealed a critical gap between receptor occupancy and T cell functionality: cells whose PD-1 receptors were fully occupied by the drug did not necessarily show the downstream signalling and cytokine production that clinicians would want to see. The new study translates that laboratory observation into a quantitative, patient-scale simulation framework.

The simulations produced a striking and, for the field, uncomfortable result. All three approved regimens achieved near-complete PD-1 receptor occupancy, both in the circulation and within the tumour microenvironment. On the traditional view, this means all three doses should be pharmacodynamically equivalent, and indeed this saturation logic is precisely why regulators and developers accepted the regimens as interchangeable. Yet when the researchers looked at predicted interleukin-2 concentrations, a very different picture emerged. The cytokine levels were predicted to rise and fall throughout the dosing interval, tracking the concentration of pembrolizumab itself rather than the occupancy of its receptor.

Even more provocatively, the 400 milligram every-six-weeks regimen, the highest total dose per interval, produced the highest predicted interleukin-2 levels. If immune activation rather than receptor saturation is what drives anti-tumour efficacy, then the longest-interval regimen may not be a mere convenience option but potentially the most immunologically active of the three. The authors are careful to note that interleukin-2 is a marker, not a proven mediator of clinical response, and that more activation is not automatically better; excessive immune stimulation can contribute to toxicity. But the finding decisively breaks the assumed link between occupancy and pharmacodynamic effect.

A second important nuance concerned the tumour itself. Changes in intratumoural interleukin-2 concentrations were predicted to be considerably less pronounced than those in plasma. In other words, even if systemic immune activation fluctuates substantially between doses, the immune microenvironment inside the tumour may experience a more buffered response. This has implications for how biomarkers are interpreted: a blood sample showing robust cytokine swings may not faithfully represent what is happening at the site where the immune system meets the cancer. It also raises the possibility that intratumoural pharmacodynamics, not plasma pharmacokinetics, should be the target of future dose optimisation efforts.

The broader context makes these findings timely. Pembrolizumab is expensive, and health systems worldwide have scrutinised whether lower doses or longer intervals could deliver the same benefit at reduced cost. Pharmacokinetic simulation studies and even randomised trials of low-dose immunotherapy in head and neck cancer have suggested that less drug may suffice. Meanwhile, other lines of research have explored whether the timing of infusion within the day, circadian chronotherapy, influences survival. What has been missing from all these debates is a validated pharmacodynamic marker that actually reflects the biological effect the drugs are meant to produce. This study argues that receptor occupancy, the marker the field has relied upon, fails that test.

The authors conclude that receptor occupancy is an inadequate pharmacodynamic surrogate for pembrolizumab and, by extension, for the broader class of PD-1 inhibitors. They call for the development of robust pharmacodynamic markers and, crucially, a clearer definition of the level and pattern of immune activation required for optimal efficacy. Until such markers exist, dose selection for checkpoint inhibitors will remain guided by surrogates that may bear little relationship to the biology that matters. The study, funded by Stichting Treatmeds as part of the NVALT30/DEDICATION-1 trial programme, was approved by the ethics committee METC Oost-Nederland and conducted according to the Declaration of Helsinki. Its message is likely to resonate far beyond lung cancer: for a drug class that has transformed oncology, the question of how much drug patients really need may have been asking the wrong question all along.

Subject of Research: Translational pharmacokinetic-pharmacodynamic modelling of pembrolizumab dosing, receptor occupancy and immune activation in non-small cell lung cancer

Article Title: Translational modelling challenges receptor‑occupancy‑based dosing of PD‑1 inhibitors like pembrolizumab

Article References: Verdonk, J. D. J., Otten, L.-S., Montaseri, G., van den Heuvel, M. M., Smeets, R. L., Koenen, H. J. P. M., & ter Heine, R. (2026). Translational modelling challenges receptor‑occupancy‑based dosing of PD‑1 inhibitors like pembrolizumab. British Journal of Cancer. https://doi.org/10.1038/s41416-026-03612-w

Image Credits: AI Generated

DOI: 10.1038/s41416-026-03612-w

Keywords: pembrolizumab, PD-1 inhibitors, receptor occupancy, cancer immunotherapy, pharmacokinetic modelling, interleukin-2, non-small cell lung cancer, dose optimisation, pharmacodynamics, immune checkpoint inhibitors, tumour penetration, drug dosing