The open-label, single-center study used a conventional 3 + 3 dose-escalation design. Participants received NK510 at 6 × 10^9, 9 × 10^9, or 12 × 10^9 cells in six consecutive weekly infusions, together with the same PD-1 inhibitor used before enrollment. NK510 is an allogeneic natural killer-cell product created using base editing to disrupt TIGIT. The product was designed to enhance natural killer-cell activation in the tumor microenvironment. The primary endpoint was safety, including assessment of dose-limiting toxicities. Secondary endpoints were objective response rate, disease control rate, progression-free survival, and duration of response.

Among the nine treated patients, the objective response rate was 11.1%, with a 95% confidence interval of 0.3–48.2%. The disease control rate was 66.7%, with a 95% confidence interval of 29.9–92.5%. Median progression-free survival was estimated at 8.6 months, with a 95% confidence interval of 1.53 months to not reached. These estimates have substantial uncertainty because they were based on only nine participants. The results describe observations from this early phase I cohort and do not demonstrate that NK510 increased response, disease control, or progression-free survival relative to PD-1 blockade alone.

Fever and chills were the most common treatment-related adverse events. The investigators reported no unexpected safety signals and no grade 3 or higher immune-related adverse events. Exploratory cytokine analyses showed variable changes across patients and sampling time points, providing preliminary biological observations rather than evidence of a consistent mechanism. Overall, the findings support the feasibility and preliminary tolerability of TIGIT-disrupted NK510 combined with PD-1 blockade at the doses evaluated. The limited sample size restricts the ability to characterize uncommon adverse events, compare dose levels reliably, or assess antitumor activity with precision.

The study enrolled a narrowly defined population: patients with advanced, PD-1-pretreated non-small cell lung cancer, specifically described in the study background as including patients without actionable driver alterations. Its single-center design, first-in-human dose-escalation format, and enrollment of only nine patients make the results suitable primarily for evaluating initial safety and feasibility. The authors concluded that the preliminary disease-control signal warrants further investigation in larger prospective trials. Whether NK510 provides a measurable clinical benefit, which doses should be carried forward, and how the combination performs in broader populations remain unresolved by these data.

Subject of Research: Phase I evaluation of TIGIT-disrupted NK510 combined with PD-1 blockade in advanced non-small cell lung cancer

Article Title: A phase I clinical trial of NK510 combined with PD-1 blockade in patients with advanced non-small cell lung cancer

Article References: Cheng, J., Cheng, Q., Zhu, S., Mei, Y., Yang, F., Zhan, P., Xu, T., Yan, J., Song, X., Zhang, J., Han, H., Yuan, D., Yao, Y., & Lv, T. (2026). A phase I clinical trial of NK510 combined with PD-1 blockade in patients with advanced non-small cell lung cancer. Cancer Immunology, Immunotherapy. https://doi.org/10.1007/s00262-026-04604-8

Image Credits: AI Generated

DOI: 10.1007/s00262-026-04604-8

Keywords: NK510, natural killer cells, TIGIT, PD-1 blockade, non-small cell lung cancer, phase I trial, dose escalation, cancer immunotherapy, treatment safety, tumor microenvironment, phase, clinical

The logic of the discovery is elegant in its biochemical economy. Adenosine is a well-known signaling molecule in healthy tissue, where it accumulates during periods of stress, inflammation, or hypoxia and helps dampen excessive immune responses to prevent collateral tissue damage. Tumors have long been suspected of hijacking this safety valve, but the question of how a specific oncogene might actively orchestrate adenosine accumulation had remained poorly defined. The new study answers that question with unusual precision, showing that oncogenic KRAS attacks adenosine metabolism from two directions at once—boosting the machinery that produces the molecule while simultaneously disabling the machinery that destroys it.

On the production side, the researchers found that mutant KRAS acts through the BRAF signaling pathway to upregulate ecto-5′-nucleotidase, an enzyme encoded by the NT5E gene and better known by its alternative name, CD73. This enzyme sits on the outer surface of cancer cells and performs the final step in a cascade that begins with extracellular ATP, the energy currency released by dying and stressed cells. Enzymes such as ENTPD1 strip phosphate groups from extracellular ATP to yield AMP, and NT5E then cleaves the remaining phosphate to liberate free adenosine directly into the extracellular space. By cranking up NT5E expression, KRAS-mutant cells essentially convert the debris of tumor turnover into a potent immunosuppressant, manufacturing adenosine right at the front line where immune cells patrol.

Production alone, however, would not be enough if the accumulating adenosine were quickly degraded. This is where the second arm of the scheme comes in. The team demonstrated that KRAS signaling, acting through the AKT pathway, suppresses adenosine deaminase, or ADA—the enzyme responsible for breaking adenosine down into inosine. The consequence of this coordinated manipulation is pathological: adenosine is produced faster and cleared more slowly, allowing it to build up to concentrations that would never be tolerated in healthy tissue. The researchers quantified this accumulation using liquid chromatography–tandem mass spectrometry, confirming that adenosine levels rise dramatically in KRAS-driven tumors compared with their non-malignant or KRAS-wildtype counterparts.

The functional consequences for the immune system are exactly what one would predict from adenosine’s known biology. When T cells encounter high concentrations of extracellular adenosine, they engage A2A adenosine receptors on their surface, which triggers intracellular signaling that blunts the production of interferon-gamma and interleukin-2, the cytokines that drive effective antitumor attack. Proliferation slows, cytotoxic activity wanes, and the T cells that should be tearing into the tumor instead drift toward a dysfunctional, exhausted state. Using immune–tumor co-culture assays, the team showed that adenosine-rich conditioned media from KRAS-mutant cells markedly impaired T-cell function, and that this impairment could be reversed when adenosine was removed from the equation.

Crucially, the study did not stop at cell culture. The investigators employed inducible KRAS cell models, human tumor specimens, and syngeneic mouse models to establish that the adenosine axis operates in living tumors. Flow cytometry and immunohistochemistry revealed that adenosine-laden KRAS tumors were infiltrated by fewer functional T cells and harbored a more immunosuppressive microenvironment overall. Analysis of human tumor samples corroborated the mouse data, showing the expected relationship between KRAS-driven signaling, NT5E and ADA expression, and the immune landscape of the tumors. The consistency across model systems and human tissue lends considerable weight to the conclusion that this is not a laboratory artifact but a genuine feature of KRAS-mutant cancers in patients.

The therapeutic implications are where the study becomes truly exciting. The researchers tested three complementary ways of attacking the adenosine axis. First, genetic silencing of NT5E in tumor cells restored antitumor immunity, demonstrating that the ectonucleotidase is a viable point of intervention. Second, and perhaps most creatively, they deployed nanoparticles loaded with adenosine deaminase itself—packaging the very enzyme that KRAS-mutant tumors suppress into poly(lactic-co-glycolic acid) delivery vehicles that could enzymatically deplete adenosine in the tumor microenvironment. The strategy is conceptually striking: rather than blocking a receptor or inhibiting a kinase, it simply replenishes the missing metabolic cleanup crew. When ADA nanoparticles converted adenosine into inosine, they performed a kind of metabolic alchemy, transforming an immunosuppressive metabolite into an immune-stimulatory one, since inosine has been shown in prior work to fuel T cell activity rather than dampen it.

Third, the team turned to pharmacological blockade of the adenosine A2A receptor, the molecular dock where adenosine delivers its calming signal to immune cells. A2AR inhibition suppressed tumor growth in mouse models through a dual mechanism that the authors highlight as particularly attractive: the drug simultaneously enhanced immune activation by preventing adenosine from silencing T cells and directly impaired the viability of KRAS-driven cancer cells themselves. That second, tumor-intrinsic effect suggests that KRAS-mutant cells may become dependent on adenosine signaling in ways that extend beyond immune manipulation, raising the possibility that A2AR antagonists could deliver a one-two punch against this tumor type.

Perhaps the most clinically resonant result came from combining these metabolic interventions with PD-1 checkpoint blockade, the immunotherapy class that has transformed treatment for many cancers but frequently fails in KRAS-mutant disease. In the syngeneic mouse models, both genetic NT5E silencing and ADA nanoparticle treatment potentiated the efficacy of anti-PD-1 antibodies, converting a weak or absent response into a robust one. The interpretation is straightforward: checkpoint inhibitors release the brakes on T cells, but if those T cells are metabolically sedated by adenosine, releasing the brakes accomplishes little. By clearing adenosine from the microenvironment first, the metabolic interventions allow the checkpoint blockade to function as intended. This framing positions adenosine targeting as a rational partner for existing immunotherapy rather than a replacement for it.

The study, published on 13 October 2026 in Molecular Cancer with the DOI 10.1186/s12943-026-02810-7, was supported by funding from the National Natural Science Foundation of China and several institutional programs, and the authors declare no competing interests. As with any preclinical work, the road from mouse models to patients is long, and the safety and pharmacology of ADA nanoparticles in humans remain to be established. But the conceptual contribution is substantial: a previously unrecognized KRAS-controlled adenosine metabolic axis now stands revealed as a driver of immune evasion, and three distinct points along that axis—NT5E, ADA, and A2AR—offer druggable targets. For the large population of patients whose KRAS-mutant tumors have shrugged off immunotherapy, the prospect of restoring T-cell function simply by correcting a metabolic imbalance is a compelling one, and it ensures that adenosine metabolism will be watched closely as a next frontier in cancer immunotherapy research.

Subject of Research: KRAS-driven adenosine metabolic reprogramming and immune evasion in cancer

Article Title: Oncogenic KRAS drives immune evasion through adenosine metabolic reprogramming mediated by NT5E and ADA

Article References: Yuan, J., Ding, W., Zhang, Y., Liu, R., Yang, J., Lu, W., Huo, B., Liu, Q., Wei, X., Chiao, P. J., Glorieux, C., Wen, S., Nicot, C., Liu, P., & Huang, P. (2026). Oncogenic KRAS drives immune evasion through adenosine metabolic reprogramming mediated by NT5E and ADA. Molecular Cancer. https://doi.org/10.1186/s12943-026-02810-7

Image Credits: AI Generated

DOI: 10.1186/s12943-026-02810-7

Keywords: KRAS, adenosine, NT5E, ADA, A2AR, immune evasion, tumor microenvironment, PD-1 blockade, cancer metabolism, T cells, immunotherapy resistance, inosine

The research, a collaboration between teams at Shandong Provincial Hospital Affiliated to Shandong First Medical University in China and Science for Life Laboratory at Uppsala University in Sweden, focused on a signaling axis that has long been implicated in cancer progression but rarely examined through an immunological lens. The FGFR family of receptor tyrosine kinases, comprising FGFR1 through FGFR4, regulates cell proliferation, survival, migration and differentiation. When these receptors are activated by their ligands or altered by genetic changes, they can drive tumor growth and, as mounting evidence suggests, help cancers hide from the immune system. The researchers set out to determine whether silencing this pathway in colorectal cancer could strip away one layer of that camouflage.

The team’s experimental strategy combined laboratory models with large-scale genomic data. In murine colorectal cancer models, they tested FGFR pathway inhibition alone and in combination with antibodies that block PD-1, the checkpoint receptor that exhausted T cells use to disengage from tumor cells. In parallel, they built in vitro co-culture systems in which T cells and tumor cells interact under controlled conditions, allowing them to measure precisely how FGFR3 blockade changes T cell activation. To connect these mechanistic findings to human disease, they performed RNA sequencing and bioinformatic analyses, including an evaluation of The Cancer Genome Atlas (TCGA), one of the largest publicly available collections of tumor transcriptomic and clinical data.

The results point to a coherent immunological mechanism. When the researchers combined FGFR inhibition with PD-1 blockade, they observed a significant reduction in T cell exhaustion, the dysfunctional state that renders tumor-infiltrating lymphocytes unable to kill their targets. Exhausted T cells express inhibitory receptors, lose their cytotoxic potency and secrete diminished amounts of inflammatory mediators. By reversing this state, the combination treatment appeared to reinvigorate the cellular arm of the antitumor immune response. Equally striking was the effect on myeloid cells: the treatment promoted macrophage repolarization toward an antitumor phenotype. Macrophages are notoriously plastic; within tumors they often adopt a pro-tumor, immunosuppressive identity that suppresses T cells and promotes tissue invasion. Shifting them back toward an inflammatory, tumor-fighting state represents a second, complementary lever on the immune microenvironment.

Transcriptomic profiling provided a molecular explanation for these cellular observations. RNA sequencing revealed that combined FGFR inhibition and PD-1 blockade upregulated immune-related pathways and activated immune-stimulatory genes, effectively rewiring the tumor’s gene expression program toward one that recruits and supports immune attack. In the co-culture experiments, the most direct functional readout came from FGFR3-specific monoclonal antibody treatment, which enhanced the release of interferon-gamma following PD-1 blockade. Interferon-gamma is a signature cytokine of activated T cells and natural killer cells, and its production is a hallmark of productive antitumor immunity. The finding that a monoclonal antibody against a single receptor, FGFR3, could boost this cytokine response when paired with checkpoint blockade suggests that the effect is not a diffuse consequence of general growth factor withdrawal but a targeted immunological shift.

The clinical relevance of these findings was reinforced by the TCGA analysis. The researchers found that high FGFR3 expression correlates with worse prognosis in colorectal cancer patients, linking the receptor’s activity to patient outcomes in a large human cohort. This epidemiological signal matters because it suggests that FGFR3 is not merely a passenger in colorectal tumors but a biologically meaningful participant whose expression marks aggressive disease. It also provides a potential biomarker: patients whose tumors express high levels of FGFR3 might be the ones most likely to benefit from a combination strategy that includes FGFR inhibition, an approach that aligns with the broader movement toward biomarker-guided immunotherapy combinations.

The significance of the work lies in the specific problem it addresses. Microsatellite stable colorectal cancer has been described as a cold tumor type, characterized by low mutational burden, sparse T cell infiltration and an immunosuppressive stroma. Checkpoint inhibitors work best when pre-existing antitumor T cells are present but restrained; in MSS colorectal cancer, that substrate is often missing. Strategies to convert cold tumors into hot ones, including oncolytic viruses, radiation, chemotherapy and targeted agents, have produced mixed results. The new study adds FGFR inhibition to this arsenal, and its dual mechanism, reducing T cell exhaustion while repolarizing macrophages, targets two distinct pillars of immune suppression simultaneously. That combination of effects may explain why the pairing with PD-1 blockade produced such pronounced immunological changes in the models.

It is worth placing the findings in the context of existing FGFR-directed therapeutics. Several FGFR inhibitors, mostly small-molecule kinase inhibitors such as erdafitinib and pemigatinib, are already approved for other cancers with FGFR alterations, including urothelial carcinoma and cholangiocarcinoma. The prospect of extending this drug class into colorectal cancer, not as a standalone cytotoxic agent but as an immunomodulatory partner for checkpoint blockade, represents a conceptual repurposing. The Swedish-Chinese team’s use of an FGFR3-specific monoclonal antibody in vitro also highlights an alternative modality: receptor-specific antibodies may offer cleaner target engagement than broad-spectrum kinase inhibitors, potentially limiting the toxicities that have complicated FGFR-targeted therapy, such as hyperphosphatemia and ocular side effects.

As with any preclinical study, important caveats apply. The work was conducted in murine models and in vitro co-culture systems, which, however sophisticated, cannot fully reproduce the complexity of human colorectal tumors, including their heterogeneous microbiomes, stromal architectures and evolutionary histories. The authors themselves frame their findings as providing a rationale for further investigation rather than as proof of clinical efficacy. Translating the combination into patients will require careful dose-finding, attention to the safety of adding FGFR inhibition to immunotherapy, and clinical trials designed to test whether the biomarker signal from TCGA, high FGFR3 expression predicting poor prognosis, also predicts benefit from the combination. The study was approved by the Review Committee of Shandong First Medical University Affiliated Provincial Hospital and conducted in compliance with ARRIVE 2.0 reporting guidelines, and the authors declare no competing interests.

Nevertheless, the study adds an important piece to one of oncology’s most pressing puzzles: how to make immunotherapy work for the patients who currently derive no benefit from it. By demonstrating that FGFR pathway inhibition reduces T cell exhaustion, repolarizes macrophages, upregulates immune-stimulatory genes and enhances interferon-gamma release in the presence of PD-1 blockade, the researchers have articulated a mechanistically grounded rationale for a new combination strategy in MSS colorectal cancer. If subsequent studies in patients confirm what the mouse models and genomic analyses suggest, the FGFR axis, long studied as a driver of tumor growth, may find a second career as a gatekeeper of antitumor immunity, and its inhibition may help open the door that checkpoint inhibitors alone have been unable to unlock for the majority of colorectal cancer patients.

Subject of Research: FGFR pathway inhibition combined with PD-1 blockade to enhance antitumor immunity in microsatellite stable colorectal cancer

Article Title: FGFR pathway inhibition enhances PD-1 blockade and modulates antitumor immunity in colorectal cancer models

Article References: Shang, Z., Jing, C., Liu, J., Zhang, B., Rúbies Bedós, M., Papakyriacou, I., Mao, Y., & Chen, Y. (2026). FGFR pathway inhibition enhances PD-1 blockade and modulates antitumor immunity in colorectal cancer models. BMC Cancer, 26(1), Article 1227. https://doi.org/10.1186/s12885-026-17105-9

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17105-9

Keywords: colorectal cancer, FGFR signaling, PD-1 blockade, immunotherapy, microsatellite stable, T cell exhaustion, macrophage repolarization, interferon-gamma, TCGA, combination therapy, immune checkpoint blockade, tumor microenvironment

The investigation began as a large-scale computational sweep. The team integrated bulk transcriptomic datasets, single-cell RNA sequencing and spatial transcriptomics from lung adenocarcinoma patients, cross-referencing these molecular maps with clinical cohorts that had received immune checkpoint blockade. Using weighted gene co-expression network analysis, survival meta-analysis and tissue enrichment scoring, they hunted for stromal cell subpopulations whose presence tracked with aggressive disease and poor immunotherapy outcomes. That search converged on a single culprit: a myofibroblastic cancer-associated fibroblast subset defined by high expression of MMP11, alongside the canonical contractile genes ACTA2 and TAGLN. These MMP11-positive myCAFs were enriched not only in primary lung tumors but also in metastatic lesions, and their abundance correlated with advanced tumor stage, metastatic spread, shorter overall survival and markedly reduced benefit from checkpoint inhibitors.

What makes this finding technically significant is the way the team moved beyond correlation. Spatial transcriptomic deconvolution, a computational method that infers which cell types occupy which physical niches within a tissue section, showed that MMP11-positive myCAFs consistently co-localized with SPP1-positive macrophages, a pro-tumor myeloid population that was itself enriched in malignant and metastatic lung adenocarcinoma tissue. The researchers then confirmed this spatial partnership in human clinical specimens using multiplex immunohistochemistry, a staining technique that visualizes several protein markers simultaneously on a single tissue slide. The two cell types were not merely neighbors in the same tumor; they occupied the same microanatomical neighborhoods, suggesting a functional relationship rather than coincidental distribution.

To identify the molecular language spoken between these cells, the team performed ligand-receptor interaction analysis on their single-cell and spatial data, complemented by virtual gene knockout experiments that computationally predicted the downstream consequences of removing specific signaling molecules. WNT5A emerged as the dominant macrophage-derived mediator linking SPP1-positive macrophages to myCAF activation. WNT5A is a member of the Wingless-related integration site family, a group of secreted glycoproteins that orchestrate embryonic development, tissue patterning and, in cancer, a bewildering array of pro-tumor behaviors. In this context, the analysis indicated that WNT5A released by macrophages acts on fibroblasts, driving them toward a matrix-remodeling, contractile state.

The mechanistic story has two halves. On the macrophage side, the researchers found that SPP1-positive macrophages exhibited activation of transcriptional programs governed by the non-canonical NF-kappaB factors NFKB2 and RELB. When they generated macrophages that overexpressed SPP1 in vitro, levels of Nfkb2, Relb and WNT5A protein all rose, placing SPP1 upstream of a signaling cascade that culminates in WNT5A production. This is a notable detail because it ties a well-known pro-tumor macrophage marker to a specific transcriptional pathway and a specific secreted output, giving the field a concrete molecular handle on a cell type that has often been described only by its marker genes.

On the fibroblast side, the team built a macrophage-CAF co-culture system in which SPP1-overexpressing macrophages and MMP11-overexpressing fibroblasts could interact directly. When fibroblasts were stimulated with WNT5A, they showed activation of YAP-associated signaling and increased expression of INHBA, the gene encoding the activin A subunit. YAP, the transcriptional co-activator downstream of the Hippo pathway, is a well-established sensor of mechanical forces and tissue stiffness, and its activation in fibroblasts is a hallmark of the myofibroblastic state. Functionally, WNT5A-stimulated fibroblasts migrated more readily, contracted more forcefully and deposited more extracellular matrix than their untreated counterparts. Each of these behaviors contributes to the desmoplastic reaction, the dense fibrous scar tissue that many solid tumors build around themselves.

The in vivo experiments brought the story into living systems. The researchers established murine tumor models and evaluated them with in vivo imaging, flow cytometry, atomic force microscopy, hematoxylin and eosin staining, Masson staining and multiplexed immunohistochemistry. Atomic force microscopy deserves particular mention: it measures tissue stiffness at the nanoscale by probing the physical resistance of the extracellular matrix, providing a direct readout of the mechanical remodeling that the fibroblasts were predicted to drive. The results were consistent with the in vitro findings. When WNT5A signaling was activated in the tumor microenvironment, collagen deposition increased, tissue stiffness rose, and MMP11-positive CAFs accumulated.

Most consequentially for patients, WNT5A activation impaired the therapeutic efficacy of PD-1 blockade in these animal models. Flow cytometry revealed reduced infiltration of CD8-positive T cells into the tumors, the very effector cells that anti-PD-1 antibodies are designed to unleash. The picture that emerges is a coherent immunosuppressive circuit: SPP1-positive macrophages, driven by NFKB2/RELB programs, secrete WNT5A; WNT5A activates YAP/INHBA signaling in fibroblasts; the fibroblasts remodel and stiffen the matrix; and the resulting dense, rigid stroma excludes cytotoxic T lymphocytes, leaving checkpoint inhibitors with little to work with even when the drug successfully engages its target on T cells.

The clinical implications are substantial. Immune checkpoint blockade has reshaped outcomes in lung adenocarcinoma, yet primary and acquired resistance remain stubborn problems, and stromal exclusion of T cells is one of the best-documented mechanisms of failure. By identifying SPP1-positive macrophages and MMP11-positive myCAFs as a spatially coupled, functionally linked pair, and by pinpointing WNT5A as the bridge between them, the study offers a set of potential biomarkers and drug targets. Patients whose tumors are rich in MMP11-positive myCAFs might be identified in advance as unlikely to benefit from PD-1 monotherapy and steered toward combination strategies. Meanwhile, the WNT5A-YAP axis suggests that disrupting macrophage-fibroblast communication could soften the tumor matrix, restore T-cell infiltration and resensitize tumors to immunotherapy. The authors note that their findings highlight a potential therapeutic strategy to overcome immune checkpoint blockade resistance, though translating that insight into clinics will require inhibitors capable of safely modulating WNT signaling in humans.

Methodologically, the study is also a demonstration of how modern cancer biology is increasingly conducted. No single technique carried the argument; instead, bulk transcriptomics established population-level associations, single-cell RNA sequencing resolved the relevant cell states, spatial transcriptomics and multiplex immunohistochemistry anchored those states in physical tissue architecture, virtual knockout and co-culture experiments tested causal mechanisms in vitro, and mouse models with mechanical measurements confirmed the circuit in vivo. The human specimens were obtained under ethics approval from Zhejiang Cancer Hospital, and the work was supported by the National Natural Science Foundation of China and the Traditional Chinese Medicine Scientific Research Foundation of Zhejiang Province. As with any study that combines computational inference with experimental validation, the next step will be independent confirmation in larger immunotherapy cohorts and the development of clinically tractable ways to interrupt the WNT5A signal. If those hurdles can be cleared, the stromal conversation between macrophages and fibroblasts may become one more vulnerable link in the armor that lung adenocarcinomas use to shield themselves from the immune system.

Subject of Research: The role of SPP1-positive macrophage-derived WNT5A in MMP11-positive myofibroblastic cancer-associated fibroblast activation, matrix remodeling, and immunotherapy resistance in lung adenocarcinoma.

Article Title: SPP1⁺ macrophage-derived WNT5A contributes to MMP11⁺ myCAF-mediated matrix remodeling and immunotherapy resistance in lung adenocarcinoma

Article References: Wang, M., Zhang, P., Li, X., Shao, L., Dai, S., & Chen, Z. (2026). SPP1⁺ macrophage-derived WNT5A contributes to MMP11⁺ myCAF-mediated matrix remodeling and immunotherapy resistance in lung adenocarcinoma. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-09069-y

Image Credits: AI Generated

DOI: 10.1186/s12967-026-09069-y

Keywords: lung adenocarcinoma, WNT5A, SPP1 macrophages, cancer-associated fibroblasts, MMP11, matrix remodeling, immunotherapy resistance, PD-1 blockade, tumor microenvironment, YAP signaling, single-cell RNA sequencing, spatial transcriptomics

The biological logic behind the combination rests on a family of proteins called inhibitors of apoptosis, or IAPs. Three members of this family, cIAP1, cIAP2 and XIAP, act inside cells as gatekeepers of cell death and inflammatory signaling. Rather than simply preventing suicide, these proteins actively suppress a form of cell death driven by RIPK1, a signaling kinase that can trigger what scientists call immunogenic cell death. When tumor cells die immunogenically, they release signals that recruit and activate both innate and adaptive immune responses, effectively turning a dying tumor cell into a vaccine. By keeping this pathway in check, IAPs help tumors evade immune surveillance and blunt the effectiveness of drugs that release the brakes on T cells.

Tolinapant was designed to remove that shield. It is a non-peptidomimetic antagonist, meaning it binds the IAP proteins without mimicking the natural peptides that normally regulate them, and it does so with balanced activity against all clinically relevant IAP family members. The intended effect is to lower the threshold at which tumor necrosis factor, or TNF, becomes lethal to the tumor cell. In practical terms, the drug makes cancer cells far more vulnerable to being killed by T cells, the very cells that pembrolizumab unleashes by blocking the PD-1 checkpoint. The trial therefore tested whether priming tumors with tolinapant could convert immunologically cold or resistant cancers into ones that respond to PD-1 blockade.

The ASTEROID trial enrolled patients with advanced solid tumors and followed a classic phase I design. The primary endpoints were safety and the identification of a recommended phase 2 dose, while secondary endpoints captured anti-tumor activity and the pharmacokinetics of the combination. Dosing of tolinapant followed an intermittent schedule of seven days on treatment followed by fourteen days off, an approach intended to balance target engagement against toxicity. Pembrolizumab was administered on its standard intravenous schedule. The combination proved well tolerated overall, an important finding because IAP antagonists can, in principle, sensitize normal cells to TNF-driven inflammation as well as tumor cells.

The recommended phase 2 dose was established at 150 milligrams of tolinapant given on the intermittent schedule alongside pembrolizumab. Within that framework, the investigators observed early but meaningful evidence of efficacy. The overall response rate across the treated population reached 33 percent, a striking figure for a phase I study in a heavily pretreated cohort of mixed tumor types. Particularly notable were responses in estrogen receptor-positive breast cancer, a disease subtype that has historically resisted immune checkpoint blockade and is generally considered immunologically quiet. Seeing durable responses in this setting suggests that lowering the TNF cytotoxicity threshold can genuinely reprogram how tumors interact with the immune system.

Beyond the headline response rate, the trial’s translational component may prove its most enduring contribution. The team performed integrated analyses of tumor biopsies and blood samples to understand why some patients responded and others did not. Responders carried tumors characterized by a TNF and interferon-enriched inflammatory microenvironment, a molecular signature indicating that the intended biology, the sensitization of tumor cells to cytokine-driven killing, was actually occurring in patients. Responders also showed increased tumor antigenicity, meaning their cancers displayed more molecular features that the immune system could recognize as foreign, together with enhanced diversity of T cell receptor clones, a sign that a broader repertoire of T cells had been mobilized against the tumor.

Resistance, by contrast, had a coherent fingerprint of its own. Non-responding tumors were dominated by a niche of immune suppressor cells, specifically tumor-associated macrophages and regulatory T cells, orchestrated by the chemokine receptors CCR4, CCR6, CCR7 and CCR8. These receptors guide the trafficking of immune cells, and their enrichment points to a microenvironment in which suppressive myeloid and regulatory populations crowd out effector T cells, absorbing the benefits of checkpoint release. This finding suggests that patients who fail the tolinapant-pembrolizumab combination might in future be candidates for additional agents that deplete or reprogram macrophages and regulatory T cells, potentially creating triple or quadruple combinations tailored to the biology of each tumor.

The trial was funded by Cancer Research UK and Astex Pharmaceuticals, now part of Taiho Oncology, with drug supplied through Astex and Merck Sharp & Dohme’s investigator-initiated studies program. It was conducted across UK centers including The Royal Marsden, Cambridge University Hospitals and the Institute of Cancer Research’s Drug Development Unit, with laboratory work spanning the Meier Lab, the Centre for Evolution and Cancer and collaborating groups in Australia and Sweden. The study also reflects a growing trend in early-phase oncology: rather than treating phase I trials as pure safety exercises, the investigators embedded deep molecular profiling from the outset, so that every patient’s response contributed to a mechanistic map of the drug’s action.

For the field, the results constitute clinical proof of concept that dual blockade of IAP proteins and PD-1 can sensitize tumors to immunotherapy. They also deliver a practical dividend in the form of candidate biomarkers. The TNF and interferon signature, antigenicity measures and T cell receptor clonality could be developed into diagnostic tests to select patients most likely to benefit, while the CCR-driven suppressor niche signature could identify those who need combination strategies beyond PD-1 blockade. Larger trials will be required to confirm efficacy, define which tumor types gain the most, and validate the biomarkers prospectively. But the ASTEROID data provide a compelling early answer to a question that has frustrated oncologists for a decade: how to make immunotherapy work for the many patients whose tumors currently ignore it. By targeting the machinery tumors use to silence inflammatory cell death, tolinapant appears to reopen a channel that cancer had carefully closed, and the 33 percent response rate, including in a notoriously immunotherapy-resistant breast cancer subtype, is the kind of signal that reshapes research agendas.

Subject of Research: A phase I trial of the IAP antagonist tolinapant combined with pembrolizumab in advanced solid tumors

Article Title: IAP antagonist tolinapant (ASTX660) in combination with pembrolizumab in advanced solid tumors: a phase I trial

Article References: Tiu, C., Yau, W., Tenev, T., Lionarons, D., Leung, C., Sanchez-Perez, V., Codacci-Pisanelli, G., Lai, X., Zachariou, A., Hussain, A., Prout, T., Parmar, M., Baikady, B., Goicoechea, M., Layzell, S., Guppy, N., Roxanis, I., Lund, T., Dos Reis, D. C., … Meier, P. (2026). IAP antagonist tolinapant (ASTX660) in combination with pembrolizumab in advanced solid tumors: a phase I trial. Nature Communications. https://doi.org/10.1038/s41467-026-77552-7

Image Credits: AI Generated

DOI: 10.1038/s41467-026-77552-7

Keywords: tolinapant, ASTX660, pembrolizumab, IAP antagonists, immunotherapy, phase I trial, advanced solid tumors, ER-positive breast cancer, immunogenic cell death, PD-1 blockade, tumor microenvironment, biomarkers

The rationale behind the study rests on a strategy that has gained considerable traction in oncology: drug repurposing. Bringing a brand-new molecule from discovery to the clinic can take well over a decade and cost more than a billion dollars, whereas established drugs come with known safety profiles, manufacturing routes, and, in some cases, prior human exposure data. Clofoctol, an antibiotic with a long clinical history in parts of Europe, had already attracted attention for direct antitumor activity in preclinical studies. What remained poorly understood—and what motivated the Beijing team led by Yue Wang, Wei Han, and Xiaozhong Peng—was whether the drug could also act on the immune landscape of glioblastoma, a tumor whose microenvironment is famously hostile to infiltrating lymphocytes.

To probe that question, the researchers turned to an orthotopic GL261 model, in which glioblastoma cells are implanted directly into the brains of immunocompetent mice. This model is widely regarded as one of the most faithful experimental systems for glioblastoma immunology because it preserves an intact blood-brain barrier and an intact immune system, both of which are essential when the question at hand concerns systemic immune trafficking. Using flow cytometry, the team compared the immune composition of tumors from clofoctol-treated animals against controls, and the differences were striking. Tumors from treated mice contained a substantially higher proportion of CD8-positive cytotoxic T cells—the immune system’s primary tumor-killing operatives—and those cells expressed elevated levels of cytotoxic effector molecules, hallmarks of a tumor microenvironment shifting from immunologically cold to immunologically active.

Perhaps the most intriguing finding, however, lay outside the tumor itself. When the researchers analyzed the composition of cells in the bone marrow, they observed that glioblastoma was associated with an accumulation of T cells sequestered in that compartment, a phenomenon consistent with the systemic T-cell dysfunction that increasingly is recognized as a barrier to immunotherapy in brain tumors. Clofoctol treatment partially relieved this sequestration, promoting a redistribution of T cells back into systemic circulation and, ultimately, into the tumor. In other words, the drug appears to work not only within the tumor microenvironment but at the level of whole-body immune architecture, releasing a reservoir of cytotoxic lymphocytes that the tumor had effectively locked away.

The causal importance of CD8-positive T cells to the therapeutic effect was confirmed in a depletion experiment. When the researchers eliminated CD8-positive T cells from the animals, the antitumor efficacy of clofoctol was markedly attenuated. That result matters because it elevates the drug from a possible bystander to a demonstrably T-cell-dependent intervention: whatever else clofoctol may be doing to tumor cells directly, its benefit in this model hinges on the presence of a functional cytotoxic T-cell population. For a field in which many repurposed drugs show antitumor effects that turn out to be independent of immunity—and therefore unlikely to synergize with checkpoint blockade—this distinction is critical.

In vitro co-culture experiments added a second layer of mechanistic support. When CD8-positive T cells were pretreated with clofoctol and then exposed to target cells, their cytotoxic activity increased, accompanied by upregulated expression of granzyme B, perforin, and interferon-gamma—the molecular arsenal that cytotoxic lymphocytes use to punch holes in target-cell membranes and trigger programmed cell death, along with the inflammatory cytokine that amplifies antitumor immune signaling. The drug, in short, did not merely deliver more T cells to the tumor; it made the T cells that arrived more lethal.

To trace the signaling pathway behind this activation, the team employed an affinity-based chemoproteomic approach known as ITSA-MS, which screens for proteins that bind a drug of interest in cellular lysates. That screen identified BCL9, a scaffolding protein best known for its role in Wnt signaling and previously implicated in various cancers, as a candidate clofoctol-responsive protein. Subsequent western blot analyses revealed that clofoctol treatment was associated with increased phosphorylation of VAV1, AKT, and ERK—a cascade of signaling events well established in T-cell activation, in which VAV1 relays receptor proximal signals downstream to AKT and ERK pathways that drive proliferation, survival, and effector differentiation. The authors are careful to note that the precise regulatory relationship between BCL9 and this phosphorylation cascade remains to be worked out, but the convergence of chemoproteomic and biochemical evidence points to a coherent mechanism by which the antibiotic potentiates T-cell function.

The translational payoff came in the combination experiments. Glioblastoma’s failure to respond to PD-1 blockade is thought to stem from multiple converging deficits: a physically and immunologically protected location behind the blood-brain barrier, a profoundly immunosuppressive microenvironment, and a systemic T-cell compartment that is itself dysfunctional. Checkpoint inhibitors address only one link in that chain—releasing the molecular brakes on T cells—but they cannot help if there are too few functional T cells reaching the tumor in the first place. Clofoctol, according to the new data, addresses complementary links in the chain by mobilizing T cells from the bone marrow and sharpening their cytotoxic program. When the researchers combined clofoctol with an anti-PD-1 antibody, the treated animals showed greater intratumoral CD8-positive T cell abundance and effector activity, tighter tumor control, and significantly prolonged survival compared with either monotherapy.

The implications extend beyond glioblastoma itself. The finding that a systemically administered, clinically familiar small molecule can redistribute T cells from a bone marrow reservoir and enhance their killing capacity suggests a generalizable strategy for tumors characterized by T-cell sequestration and exhaustion. It also adds to a growing appreciation that the bone marrow acts as a dynamic immunological compartment in cancer, one that can be therapeutically targeted rather than simply observed. If the mechanisms hold up in further studies, clofoctol-like approaches could complement checkpoint blockade in other poorly immunotherapy-responsive cancers, where the limiting factor is not T-cell priming but T-cell delivery and function.

Considerable caution is nonetheless warranted before extrapolating to patients. The findings derive from a single murine model, and glioblastoma models have a well-documented history of promising immunotherapy results that failed to translate into human benefit. The authors themselves emphasize that the link between BCL9 and the observed signaling changes requires further investigation, and the dosing, safety, and pharmacokinetic questions specific to combining an antibiotic with checkpoint inhibitors in the setting of brain tumors remain open. Still, the study exemplifies the promise of drug repurposing viewed through an immunological lens: an old molecule, examined with modern flow cytometry, chemoproteomics, and combination-design thinking, reveals an unexpected capacity to reorganize the immune system in ways that make immunotherapy work better. For a disease whose median survival has barely moved in decades, that is a direction worth pursuing with urgency.

Subject of Research: Repurposing the antibiotic clofoctol to enhance T-cell-mediated immunotherapy response in glioblastoma

Article Title: Clofoctol promotes systemic T-cell redistribution and intratumoral cytotoxicity to improve the response to PD-1 blockade in glioblastoma

Article References: Wang, Y., Li, E., Ai, C., Zhang, Y., Yin, B., Hou, L., Han, W., & Peng, X. (2026). Clofoctol promotes systemic T-cell redistribution and intratumoral cytotoxicity to improve the response to PD-1 blockade in glioblastoma. Cancer Immunology, Immunotherapy. https://doi.org/10.1007/s00262-026-04544-3

Image Credits: AI Generated

DOI: 10.1007/s00262-026-04544-3

Keywords: glioblastoma, clofoctol, drug repurposing, immunotherapy, PD-1 blockade, CD8-positive T cells, bone marrow, tumor microenvironment, BCL9, granzyme B, immune checkpoint blockade, Cancer Immunology Immunotherapy

The cancer in question is anaplastic large cell lymphoma, or ALCL, a rare T-cell non-Hodgkin lymphoma that exists in several biologically distinct forms. Systemic ALCL is classified as ALK-positive or ALK-negative depending on whether the tumor carries the ALK fusion oncogene, while separate entities include breast implant-associated ALCL and primary cutaneous ALCL. For most adults with systemic disease, first-line therapy consists of anthracycline-based chemotherapy, with the antibody-drug conjugate brentuximab vedotin combined with cyclophosphamide, doxorubicin and prednisone, known as BV-CHP, now the preferred regimen for CD30-positive cases. When the disease returns or stops responding, options include brentuximab vedotin alone, autologous or allogeneic stem cell transplantation, and ALK inhibitors for relapsed ALK-positive disease. Brentuximab vedotin achieves complete remission in roughly 60 percent of relapsed or refractory patients, but for those who fail to reach remission, median overall survival is only 9.5 months, a statistic that underscores how desperately new strategies are needed.

The patient’s journey began in May 2017, when she presented at age 75 with chronic diarrhea and weight loss. Initial workups for infections, celiac disease and inflammatory bowel disease, along with colonoscopy, all came back negative. Her symptoms worsened, and in July 2017 she developed a small-bowel obstruction requiring surgical resection. Histopathology of the resected tissue delivered the diagnosis: ALK-negative ALCL at stage IVB, meaning the disease had already spread widely. Eight cycles of the standard CHOP chemotherapy regimen produced a complete response, but the lymphoma returned just three months after treatment ended in February 2018. What followed was a years-long cycle of remission and relapse that would exhaust nearly every established option.

Second-line brentuximab vedotin at 1.8 milligrams per kilogram of body weight brought another complete response after eight cycles. Six months after the drug was stopped, the disease relapsed again in February 2019, prompting re-initiation of brentuximab vedotin for an additional 33 cycles. Once more the patient achieved a complete metabolic response, confirmed by PET/CT imaging, and treatment was discontinued in February 2021. Fifteen months later, in May 2022, a third relapse occurred. Because she had developed grade 1 to 2 peripheral neuropathy, a known cumulative toxicity of the antibody-drug conjugate, brentuximab vedotin was withheld. The team instead chose lenalidomide, an immunomodulatory agent given at 15 milligrams daily for 21 days of each 28-day cycle, which stabilized the disease temporarily. After seven cycles, the lymphoma progressed in November 2022.

A final brentuximab vedotin re-challenge, six cycles from April to August 2023, failed entirely. At that point, with few options remaining, the clinicians turned to comprehensive genomic profiling of circulating tumor DNA using the FoundationOne Liquid assay. The September 2023 analysis revealed a tumor mutational burden of 23 mutations per megabase, a figure well above the thresholds generally considered high. Tumor mutational burden and microsatellite instability have emerged as predictive biomarkers for immune checkpoint blockade in several solid tumors, where tumors carrying many mutations produce more abnormal proteins that the immune system can recognize. On that tissue-agnostic rationale, and with no standard alternatives left, the team began nivolumab, initially at 240 milligrams every two weeks and later modified to 480 milligrams every four weeks.

The response was striking. Clinical improvement appeared within two months, and at the first formal response assessment in March 2024, roughly six months after starting therapy, imaging showed a complete metabolic remission. The treatment was not without consequences: in April 2024 the patient developed grade 2 immune-related thyroiditis, an inflammation of the thyroid gland typical of checkpoint inhibitor toxicity, which was managed with thyroid hormone replacement and did not require stopping nivolumab. She continued the drug until November 2025, completing 25 months of treatment. In December 2025 she suffered a myocardial infarction requiring percutaneous coronary intervention with stent implantation, but given her sustained remission, no further nivolumab was administered. At her most recent follow-up in July 2026, eight months after the last dose, she remains in complete metabolic remission with no detectable tumor-associated alterations on repeat liquid biopsy, and reports good overall condition with an ECOG performance status of 1.

To understand how unusual this outcome is, the authors systematically reviewed the literature and found only three previously published adult cases of relapsed or refractory ALCL treated with immune checkpoint inhibitors. Chan and colleagues described a 35-year-old woman with ALK-negative disease who, after multiple chemotherapy failures, autologous transplantation and a relapse three months after allogeneic transplantation, achieved complete response on pembrolizumab within about 70 days, with elevated transaminases as the only side effect. Hebart and colleagues reported a 19-year-old man with ALK-positive disease who had relapsed despite chemotherapy, brentuximab vedotin, the ALK inhibitor crizotinib and autologous transplantation; nivolumab produced complete response within one month, with pneumonitis after 12 cycles treated successfully with corticosteroids. Barta and colleagues included one ALK-negative ALCL patient in a phase 2 trial of PD-1 or PD-L1 inhibition in relapsed T-cell lymphomas; although the trial was halted early for limited efficacy overall, that single patient remained in complete remission for 18 months at publication. A pediatric case reported by Rigaud and colleagues, a 17-year-old with ALK-positive disease treated third-line with nivolumab, adds further support, with rapid response and remission maintained 18 months after initiation.

Taken together, all four adult patients, including the present case, achieved complete remission and remained progression-free across reported observation periods of 4, 9, 18 and 33 months. Where safety data were available, adverse events were manageable and consistent with the established immune-related toxicity profile of PD-1 inhibitors, though the authors caution that patients treated after allogeneic stem cell transplantation face an elevated risk of graft-versus-host disease. The authors are equally clear about the limits of this evidence. Case reports carry strong publication bias, because unsuccessful treatments are far less likely to be published, making it impossible to estimate the true response rate of checkpoint blockade in ALCL. There is currently no validated evidence that tumor mutational burden predicts benefit from immunotherapy in ALCL or other T-cell lymphomas, so the treatment selection in this case was extrapolated from tissue-agnostic approvals in TMB-high solid tumors and should be regarded as hypothesis-generating rather than evidence-based.

Two additional findings may shape future research. Retrospective immunohistochemical analysis of the patient’s original 2017 tumor sample, performed during preparation of the manuscript, showed PD-L1 expression in 95 percent of tumor cells, though whether this contributed to the favorable response remains speculative. The biology of PD-L1 expression also differs between ALCL subtypes: in ALK-positive disease, PD-L1 is driven by oncogenic signaling downstream of ALK with constitutive STAT3 activation playing a central role, whereas ALK-negative disease lacks this driver and PD-L1 may be regulated through alternative STAT3- and MYC-dependent transcriptional programs, a distinction the authors argue demands separate evaluation of the subtypes in future studies. Serial circulating tumor DNA assessment, which tracked this patient’s response and confirmed molecular remission, may also warrant investigation as a monitoring tool in ALCL. The authors conclude that immune checkpoint inhibition should not yet be considered standard treatment for relapsed or refractory ALCL, but may be considered individually, preferably within a clinical trial or structured translational program, for patients who have exhausted established alternatives, and that prospective studies are needed to define efficacy, safety, optimal treatment duration and biomarker-guided patient selection, including rational combinations with brentuximab vedotin whose mechanisms of action may prove complementary.

Subject of Research: Immune checkpoint inhibitor therapy guided by genomic profiling in relapsed or refractory anaplastic large cell lymphoma

Article Title: Immune Checkpoint Inhibitors in Relapsed/Refractory Anaplastic Large Cell Lymphoma (ALCL): A Case Report and Review of the Literature

Article References: Klenner, C., & Singer, J. (2026). Immune Checkpoint Inhibitors in Relapsed/Refractory Anaplastic Large Cell Lymphoma ( ALCL ): A Case Report and Review of the Literature. Cancer Reports, 9(9), Article e70684. https://doi.org/10.1002/cnr2.70684

Image Credits: AI Generated

DOI: 10.1002/cnr2.70684

Keywords: anaplastic large cell lymphoma, immune checkpoint inhibitors, nivolumab, PD-1 blockade, tumor mutational burden, liquid biopsy, circulating tumor DNA, brentuximab vedotin, PD-L1 expression, T-cell lymphoma, precision oncology, case report

RAMP3 was already known to cancer biologists as a player in stromal regulation, the management of the non-cancerous scaffolding tissue that surrounds and supports tumors. What remained murky was its role in remodeling the tumor microenvironment, the complex ecosystem of immune cells, fibroblasts, blood vessels and signaling molecules in which tumors live, and in shaping resistance to immune checkpoint blockade. The Shinshu team set out to answer two questions: whether RAMP3 actively shapes an immunosuppressive tumor microenvironment, and whether blocking it could improve responses to immunotherapy. Their strategy combined direct genetic manipulation in mice with high-resolution molecular atlasing of the resulting tumors, an approach that allows researchers to move beyond correlation and establish functional cause and effect.

The experimental core of the study was a set of syngeneic mouse models of breast cancer, in which tumors are transplanted into mice with intact immune systems, making them far more faithful stand-ins for human cancer than immunodeficient models. By genetically deleting RAMP3, the researchers could watch what happened to tumor progression, immune composition and therapeutic response. The results were striking. Loss of RAMP3 suppressed primary tumor growth, reduced the spread of cancer to the lungs, and significantly improved survival. These were not subtle shifts in cell culture dishes; they were whole-animal outcomes measured in vivo, which lends considerable weight to the biological relevance of the molecule.

To understand how removing a single protein could produce such dramatic effects, the team turned to single-cell RNA sequencing, a technique that profiles the gene activity of thousands of individual cells within a tumor, allowing researchers to identify every immune cell type present and the precise states those cells occupy. The analysis revealed a fundamental reprogramming of the tumor immune landscape. In tumors lacking RAMP3, the balance of tumor-associated macrophages, the abundant scavenger cells that tumors often corrupt into allies, shifted away from M2-like states, which are classically immunosuppressive and wound-healing in character, toward antigen-presenting macrophage states that display tumor fragments to the immune system and sound the alarm. At the same time, the researchers observed increased infiltration of CD8-positive T cells, the cytotoxic soldiers that directly kill cancer cells, along with a reduction in T cell exhaustion, the dysfunctional state that renders T cells impotent in immunosuppressive environments.

The mechanistic thread connecting these changes appears to run through a well-known immune signaling pathway. RAMP3 deficiency was associated with reduced IL-4/STAT6 signaling in macrophages. Interleukin-4 signaling through the STAT6 transcription factor is a canonical driver of M2-like macrophage polarization, so damping this pathway helps explain why macrophages in RAMP3-deficient tumors adopted a more immune-activating identity. Downstream of this shift, the researchers found decreased expression of immunosuppressive genes, most notably the chemokine CCL8, a signaling molecule that recruits and organizes cells within the tumor microenvironment. Chemokines act as molecular addresses, and CCL8 appears to be one of the addresses that helps assemble an immune-excluded architecture favorable to tumor growth.

Crucially, the team did not rely on genetics alone to make this point. When they pharmacologically inhibited the synthesis of CC chemokines, the drug treatment reproduced the effects of RAMP3 deletion, providing independent evidence that the CCL8-centered chemokine circuit is a functional driver of the immunosuppressive environment rather than a mere bystander. Spatial transcriptomic analysis, which maps gene expression onto physical locations within tissue, added a geographic dimension to the story: RAMP3 and CCL8 were found to be co-localized within the tumor microenvironment, suggesting that the two molecules operate together in the same tumor neighborhoods where immune exclusion takes place.

Perhaps the most clinically consequential finding concerns immunotherapy itself. PD-1 blockade works by releasing the molecular brakes on T cells, but it can only succeed if functional T cells are present in the tumor in the first place. In tumors where macrophages have walled off the immune system, checkpoint inhibitors have little to work with. The Shinshu researchers showed that RAMP3 deficiency enhanced the efficacy of PD-1 blockade in their mouse models, effectively converting a resistant tumor into one that responds to treatment. This positions RAMP3 not simply as another tumor suppressor or oncogene, but as a regulator of immunotherapy sensitivity, a category of target that has become one of the most sought-after prizes in translational oncology.

To test whether these mouse findings translate to human disease, the team analyzed data from The Cancer Genome Atlas breast cancer cohort, known as TCGA-BRCA, one of the largest publicly available collections of human tumor genomic and clinical data. They constructed a weighted risk score combining RAMP3 with CD163, a marker of M2-like macrophages, and CD8A, a marker of cytotoxic T cells, capturing the triad of molecular features their mouse work had implicated. Patients with a higher score had significantly poorer overall survival. Importantly, the association held up in complete-case multivariable Cox models adjusted for clinicopathological variables, meaning the RAMP3-associated signature carried prognostic information beyond standard clinical measures such as tumor stage and grade. This kind of cross-species validation, in which a mechanism discovered in mice leaves a detectable fingerprint in human survival data, is exactly the standard that promising therapeutic targets must meet.

The study also exemplifies a broader methodological trend reshaping cancer research. Rather than examining tumors through a single lens, the researchers integrated in vivo genetics, single-cell transcriptomics, spatial transcriptomics and human cohort analysis into one coherent narrative. Each technique compensates for the blind spots of the others: mouse models establish causality but may not fully recapitulate human disease; single-cell sequencing reveals cell states but loses spatial context; spatial transcriptomics restores geography but at lower resolution; and human datasets provide clinical relevance but only correlation. Weaving these threads together, the authors built a case for RAMP3 that is considerably stronger than any single approach could deliver.

Significant work remains before RAMP3 reaches the clinic. The study was conducted in mice and validated against retrospective human data; prospective clinical trials targeting the RAMP3 pathway in breast cancer patients have yet to be conducted, and the precise molecular partners through which RAMP3 acts, including its role as an accessory protein for receptor systems, will require further mechanistic dissection. Nevertheless, the convergence of evidence is compelling. A molecule that was, until now, a footnote in stromal biology has emerged as a plausible regulator of the immunosuppressive tumor microenvironment, a determinant of macrophage identity, a gatekeeper of T cell infiltration, and a modifier of PD-1 blockade response. If pharmacological strategies can be developed to inhibit RAMP3 function or its downstream CCL8-driven chemokine circuit in human tumors, the researchers suggest it could open a path to overcoming checkpoint resistance in a cancer type that has largely stood apart from the immunotherapy revolution. For the many breast cancer patients whose tumors exclude immune cells and resist PD-1 inhibitors, that path, however early, is one worth watching closely.

Subject of Research: The role of RAMP3 in macrophage-driven immune exclusion and resistance to PD-1 blockade in breast cancer

Article Title: RAMP3 is associated with macrophage-driven immune exclusion and promotes resistance to PD-1 blockade in breast cancer: integrated in vivo and single-cell transcriptomic analyses

Article References: Zhang, Y., Tanaka, M., Sakurai, T., Kamiyoshi, A., Ichikawa-Shindo, Y., Guo, Q., Hoshiyama, K., Li, P., Li, J., Duan, J., Hayashi, M., Kai, K., Zhao, Y., Dai, K., & Shindo, T. (2026). RAMP3 is associated with macrophage-driven immune exclusion and promotes resistance to PD-1 blockade in breast cancer: integrated in vivo and single-cell transcriptomic analyses. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-09001-4

Image Credits: AI Generated

DOI: 10.1186/s12967-026-09001-4

Keywords: RAMP3, breast cancer, tumor microenvironment, tumor-associated macrophages, PD-1 blockade, immune checkpoint resistance, CCL8, IL-4/STAT6 signaling, single-cell RNA sequencing, spatial transcriptomics, CD8-positive T cells, TCGA-BRCA

Tumor-associated macrophages, or TAMs, are among the most numerous immune cells in the hepatocellular carcinoma microenvironment, and their prevailing M2-like state is a principal reason why checkpoint inhibitors so often fall short. These macrophages secrete immunosuppressive cytokines such as interleukin-10 and transforming growth factor-beta, suppress cytotoxic T lymphocytes, and actively construct a barrier against immune attack. C5aR1, a G-protein-coupled receptor normally engaged by the complement fragment C5a during inflammatory responses, is highly expressed on these TAMs, making it an attractive point of intervention. Despite this biological logic, no C5aR1-targeted cancer therapy has ever been approved, largely because complement signaling is deeply woven into normal immune regulation and systemic blockade carries risks. The Chinese team hypothesized that LukS-PV, as a natural ligand for the human form of C5aR1, might offer a way to engage the receptor selectively on macrophages inside tumors and flip them from suppressive to inflammatory.

To test this idea rigorously, the researchers built an experimental system that could distinguish human C5aR1-dependent effects from murine biology. They established both subcutaneous tumor models and a hydrodynamic tail vein injection model that produces spontaneous liver tumors resembling immunotherapy-refractory hepatocellular carcinoma, using mice engineered to carry the human C5AR1 gene alongside wild-type controls. This design proved critical. When the animals were treated with LukS-PV, tumor growth was significantly suppressed in the humanized C5AR1 mice but not in the wild-type animals, a result that supports a mechanism specifically dependent on the human receptor. Macrophage depletion experiments further demonstrated that macrophages were essential mediators of the antitumor activity: when these cells were removed, the therapeutic benefit of LukS-PV largely disappeared, confirming that the drug’s effect runs through the macrophage compartment rather than through a direct action on tumor cells.

Single-cell RNA sequencing provided a high-resolution view of what LukS-PV actually does inside the tumor. The technique, which profiles gene expression in thousands of individual cells simultaneously, revealed that treatment reshaped the entire immune landscape of the tumor. Most strikingly, TAMs shifted away from their immunosuppressive M2-like phenotype toward inflammatory M1-like states, a transcriptional transformation accompanied by changes in the broader immune ecosystem. Flow cytometry and immunofluorescence staining of tumor tissue validated these findings in vivo, showing that the reprogrammed macrophage population was accompanied by increased infiltration of CD8-positive T cells, the cytotoxic lymphocytes responsible for killing cancer cells. Those T cells displayed enhanced effector activation and reduced markers of exhaustion, indicating that the therapy did not merely bring more immune cells into the tumor but restored their functional capacity to attack it.

The mechanistic core of the study lies in the signaling cascades that LukS-PV triggers downstream of C5aR1. Using transcriptomic and molecular analyses, the team showed that the bacterial protein inhibits C5aR1-dependent PI3K/AKT signaling within macrophages. This pathway, when active, supports the suppressive macrophage program, and its inhibition set off a cascade of downstream consequences. The researchers found that LukS-PV suppressed the GSK3β/CREB/IL-10 axis, a signaling route that drives production of interleukin-10, one of the most potent immunosuppressive cytokines in the tumor microenvironment. At the same time, treatment promoted NF-κB-associated inflammatory activation, steering macrophages toward a program characterized by pro-inflammatory gene expression. Chromatin immunoprecipitation followed by quantitative PCR was used to confirm the transcriptional wiring of this switch, linking receptor engagement to changes in the activity of specific transcription factors.

The reduction in TAM-derived interleukin-10 emerged as a pivotal consequence of this reprogramming. Interleukin-10 is a master regulator of immune suppression, and its abundance in liver tumors helps explain why CD8-positive T cells in hepatocellular carcinoma so often arrive exhausted and dysfunctional. When LukS-PV lowered IL-10 production by macrophages, the suppressive brake on T cells was released, allowing effector function to recover. The team confirmed this causally in vitro through macrophage-polarization assays and experiments using recombinant interleukin-10, which could partially restore the suppressive environment even after LukS-PV treatment. Enzyme-linked immunosorbent assays quantified the cytokine shift, and conditioned-medium experiments showed that the secreted products of reprogrammed macrophages were sufficient to influence T-cell behavior, establishing a paracrine mechanism by which macrophage reprogramming translates into T-cell revival.

Perhaps the most clinically consequential finding is that LukS-PV synergizes with immune checkpoint blockade. When the researchers combined LukS-PV with PD-1 antibodies in their models, the antitumor efficacy of the checkpoint inhibitor was substantially enhanced. This makes mechanistic sense: PD-1 blockade releases the inhibitory checkpoint on T cells, but it cannot help T cells that never become activated or that remain trapped in a suppressive microenvironment dominated by M2-like macrophages and interleukin-10. By converting the macrophage population from a suppressive to an inflammatory state, LukS-PV prepares the immunological ground on which checkpoint inhibitors operate. The combination addresses two complementary layers of immune dysfunction, the extrinsic suppression imposed by the tumor microenvironment and the intrinsic checkpoints operating on T cells themselves, offering a rationale for testing this pairing in patients whose tumors have proven refractory to immunotherapy alone.

The choice of LukS-PV as the targeting agent reflects an intriguing convergence of microbiology and cancer immunology. Panton-Valentine leukocidin is a bipartite toxin whose S component, LukS-PV, naturally recognizes human C5aR1 with high specificity. Because the receptor is a G-protein-coupled receptor expressed on myeloid cells, and because the human and mouse versions differ sufficiently that the ligand discriminates between them, the humanized mouse model was essential for demonstrating activity. The species specificity that complicates preclinical work also underscores a translational consideration: the mechanism demonstrated here is explicitly human C5aR1-dependent, which strengthens the argument for clinical relevance even as it highlights the limitations of standard murine models for evaluating such agents. The study’s use of both subcutaneous and orthotopic spontaneous models, including one designed to mimic immunotherapy-refractory disease, adds weight to the conclusion that the approach can work in a tumor microenvironment that closely resembles treatment-resistant human liver cancer.

Several questions will need answers before LukS-PV reaches the clinic. The dose, schedule, and safety profile of a molecule derived from a bacterial toxin require careful evaluation, particularly regarding off-tumor effects on myeloid cells that also express C5aR1 in inflamed tissues. The study was conducted under institutional ethics approval with rigorous monitoring of animal welfare, and the authors declare no competing interests, but the path from a humanized mouse model to a phase I trial in hepatocellular carcinoma will demand formal toxicology, pharmacokinetic characterization, and manufacturing development. Nevertheless, the conceptual advance is significant. The work identifies C5aR1 targeting as a promising translational strategy for overcoming immunotherapy resistance, and it demonstrates that a naturally occurring bacterial ligand can be repurposed as a macrophage-reprogramming agent rather than a cytotoxic one.

For patients with hepatocellular carcinoma, a disease that remains one of the leading causes of cancer mortality worldwide and for which immunotherapy benefits only a subset of those treated, the study offers a new molecular handle on the problem of resistance. By showing that the fate of tumor-associated macrophages can be deliberately redirected through a single receptor, and that this redirection unlocks the power of CD8-positive T cells and potentiates PD-1 blockade, Liu, Ma, Zhang and their colleagues have added a compelling entry to the growing list of strategies aimed at remodeling the tumor microenvironment. The idea that a component of one of medicine’s oldest adversaries, Staphylococcus aureus, might help convert cold liver tumors into hot ones is a reminder that the boundary between pathogen and medicine is often thinner than it appears, and that some of immunotherapy’s most useful tools may come from the most unexpected corners of biology.

Subject of Research: Targeting C5aR1 with LukS-PV to reprogram tumor-associated macrophages and improve immunotherapy in hepatocellular carcinoma

Article Title: LukS-PV targets human C5aR1 to reprogram tumor-associated macrophages and potentiate immunotherapy in hepatocellular carcinoma

Article References: Liu, G., Shi, L., Wei, Y., Yang, Z., Ding, P., Chang, W., Dai, Y., Nie, Z., Lu, B., Liu, X., Ma, X., & Zhang, S. (2026). LukS-PV targets human C5aR1 to reprogram tumor-associated macrophages and potentiate immunotherapy in hepatocellular carcinoma. Journal of Experimental & Clinical Cancer Research. https://doi.org/10.1186/s13046-026-03837-w

Image Credits: AI Generated

DOI: 10.1186/s13046-026-03837-w

Keywords: hepatocellular carcinoma, LukS-PV, C5aR1, tumor-associated macrophages, macrophage reprogramming, PD-1 blockade, immunotherapy resistance, IL-10, PI3K/AKT signaling, NF-kappaB, tumor microenvironment, liver cancer

The enzyme at the center of the study, adenosine deaminase acting on RNA 1, or ADAR1, is one of the principal architects of the human transcriptome. It catalyzes the conversion of adenosine to inosine, a process known as A-to-I editing, in double-stranded RNA regions. Because cellular machinery reads inosine as guanosine, this editing can recode messenger RNA transcripts, alter RNA structures, and influence how RNAs are processed, translated or degraded. ADAR1 also plays a well-documented role in innate immunity, where it marks endogenous double-stranded RNA as self and prevents spurious activation of antiviral sensors. In cancer, elevated ADAR1 activity has been linked to tumor progression and immune evasion in several contexts, but its precise contribution to how bladder cancer evades immunotherapy had remained unclear until now.

Using a combination of whole transcriptome sequencing, whole genome sequencing, immunohistochemistry, and patient-derived materials, the team, led by corresponding authors Haiwei Yang, Qiang Lu and Xiao Yang, established that targeting ADAR1 in bladder cancer cells fundamentally reshapes the immune landscape of the tumor microenvironment. When ADAR1 was disabled in experimental models, two critical changes occurred. First, tumors became infiltrated by significantly more CD8-positive T cells, the cytotoxic soldiers of the adaptive immune system that are responsible for directly killing cancer cells. Second, tumor cells increased their expression of PD-L1, the checkpoint ligand through which cancers normally suppress T cell activity. That second change might at first seem counterproductive, but it is precisely what makes the tumors vulnerable to PD-1 blockade: a tumor expressing high levels of PD-L1 but crowded with CD8-positive T cells becomes an ideal target for checkpoint inhibitors, which release the molecular brakes on the waiting immune cells.

To dissect the mechanism, the researchers engineered a mutant form of ADAR1, designated ADAR1-E912A, that is defective in its RNA editing catalytic activity. Comparing cells carrying this editing-defective mutant with cells carrying wild-type ADAR1 allowed them to separate the consequences of the enzyme’s editing function from its other activities. The editing-defective mutant preserved the ability to promote CD8-positive T cell infiltration, and the team traced this effect to the chemokine CCL5, a signaling molecule known to recruit T cells to sites of inflammation and malignancy. Cells expressing the editing-defective mutant produced and secreted more CCL5, creating a chemotactic gradient that drew cytotoxic T lymphocytes into the tumor.

The molecular explanation for the increased CCL5 proved to be a matter of RNA stability. ADAR1 normally edits the messenger RNA encoding CCL5, and these edited transcripts are recognized by endonuclease V, an enzyme that cleaves inosine-containing RNA and thereby destines it for degradation. When ADAR1’s editing function was lost, CCL5 mRNA escaped this editing-dependent degradation pathway, remained stable for longer, and accumulated to higher levels within the cell. The result was a larger pool of CCL5 available for translation and secretion. In effect, ADAR1 acts as a post-transcriptional throttle on one of the most important T cell recruitment signals in the tumor, and switching off that throttle allows the tumor to summon the very immune cells it had been keeping at bay.

The second mechanism the team uncovered concerns PD-L1, the protein through which tumors engage the PD-1 checkpoint on T cells. The researchers found that ADAR1 cooperates with DICER, the cytoplasmic enzyme that processes microRNA precursors into their mature forms, to facilitate the maturation of a specific microRNA, miR-377-3p. Intriguingly, this cooperation did not require ADAR1’s editing catalytic activity, indicating that the protein performs a scaffolding or partner role in the microRNA biogenesis pathway independent of its enzymatic function. Mature miR-377-3p, in turn, represses the expression of PD-L1. In tumors where ADAR1 is abundant, the resulting PD-L1 suppression helps malignant cells keep a low immunological profile even as they hold cytotoxic T cells outside. When ADAR1 is removed, this repression is lifted, PD-L1 rises to the tumor cell surface, and the tumor becomes, paradoxically, an excellent candidate for PD-1 blockade because it now displays the molecular handle that checkpoint drugs are designed to disengage.

Perhaps the most clinically significant element of the study is the identification of an existing drug that can be repurposed as an ADAR1 inhibitor. Fludarabine, a nucleoside analogue long used as a chemotherapeutic agent in hematologic malignancies, was found to suppress ADAR1 on two fronts simultaneously: it inhibited the enzyme’s editing activity and reduced its expression. This dual suppression reproduced the effects seen with genetic targeting of ADAR1. In experimental systems, fludarabine treatment promoted CD8-positive T cell infiltration into tumors, increased PD-L1 expression on tumor cells, and sensitized bladder cancer to PD-1 blockade therapy in both in vitro and in vivo models. The finding suggests that a drug already approved and widely characterized in the clinic could be combined with checkpoint inhibitors to extend their benefits to bladder cancer patients who currently derive little benefit from immunotherapy.

The strength of the study lies partly in the breadth of its experimental evidence. The team worked across multiple platforms, including engineered bladder cancer cell lines with distinct ADAR1 statuses, co-immunoprecipitation and RNA immunoprecipitation assays to map protein and RNA interactions, immunofluorescence combined with fluorescence in situ hybridization to localize molecular events within cells, and quantitative PCR to quantify transcript changes. In vivo, they employed the N-butyl-N-(4-hydroxybutyl) nitrosamine model, a well-established chemical carcinogenesis system for bladder cancer, alongside co-culture experiments with peripheral blood mononuclear cells and experiments using patient-derived organoids that retain features of the original tumors. This triangulation across cell culture, animal models and human-derived material lends considerable weight to the conclusion that ADAR1 targeting genuinely reprograms the tumor microenvironment rather than merely altering isolated molecular readouts.

The implications extend beyond bladder cancer itself. Cold tumors across many cancer types share the fundamental problem of T cell exclusion, and any mechanism that reliably converts cold tumors into hot ones is of broad interest to the oncology community. If ADAR1 functions as a similar gatekeeper in other malignancies, the combination of an ADAR1 inhibitor with PD-1 blockade could represent a generalizable strategy. At the same time, the work highlights the dual and sometimes opposing roles that a single RNA binding protein can play: one activity, the editing of CCL5 mRNA, suppresses immune recruitment, while another, editing-independent cooperation with DICER, suppresses PD-L1 expression. Disentangling these functions will be important as inhibitors are developed and deployed. Fludarabine itself carries a known toxicity profile, and its dosing and safety when combined with checkpoint inhibitors in solid tumors will require careful clinical evaluation. Nevertheless, by identifying a druggable molecular switch that simultaneously pulls immune cells into the tumor and exposes a checkpoint target on the tumor cell surface, the Nanjing team has provided a persuasive mechanistic blueprint for turning one of immunotherapy’s most resistant solid tumors into a far more vulnerable one.

Subject of Research: Targeting the RNA editing enzyme ADAR1 to reprogram the cold tumor microenvironment of bladder cancer and enhance PD-1 blockade immunotherapy

Article Title: Targeting ADAR1 reprograms cold tumors to hot and enhances immunotherapy in bladder cancer

Article References: Bai, K., Zhuang, J., Yu, H., Lv, J., Chen, Y., Jiang, L., Li, K., Yang, H., Lu, Q., & Yang, X. (2026). Targeting ADAR1 reprograms cold tumors to hot and enhances immunotherapy in bladder cancer. Molecular Cancer. https://doi.org/10.1186/s12943-026-02778-4

Image Credits: AI Generated

DOI: 10.1186/s12943-026-02778-4

Keywords: ADAR1, bladder cancer, RNA editing, PD-1 blockade, fludarabine, CD8-positive T cells, PD-L1, CCL5, miR-377-3p, cold tumors, tumor microenvironment, cancer immunotherapy