The platform, dubbed MnO2–R848@CM, was developed by Zhen Zhang of Sun Yat-sen University and colleagues working across institutions in China, including the Hong Kong University of Science and Technology (Guangzhou). Its architecture is deceptively simple. Ultrathin manganese dioxide (MnO2) nanosheets, roughly 84 nanometers across and a mere 1.5 nanometers thick, are first decorated with a polyethylene glycol derivative and then loaded with R848, a small-molecule agonist of Toll-like receptors 7 and 8 that acts as a potent immunological adjuvant. The drug loading reached an impressive 35.70 percent at an optimized feed ratio, held in place by a combination of Mn–N coordination bonds, pi–pi stacking interactions, and hydrophilic–hydrophobic forces mediated by the amino groups on the polymer coating.

The final and arguably most clever step is the camouflage. The researchers extracted membranes from 4T1 mouse breast cancer cells through repeated freeze–thaw cycles and co-extruded them with the drug-loaded nanosheets through a polycarbonate filter, producing particles cloaked in an authentic tumor-cell shell. Protein electrophoresis confirmed that the banding pattern of the coated particles matched that of the 4T1 membranes and was clearly distinct from membranes of 3T3 normal fibroblasts, which served as an irrelevant-membrane control. After coating, the particles grew to about 170 nanometers in lateral dimension and 15 nanometers in thickness, acquired a more negative surface charge that favors stable transport in blood, and remained well dispersed in simulated body fluids, with sizes consistently below 200 nanometers.

That disguise pays off in targeting. When the team labeled the particles with the fluorescent dye coumarin 6 and incubated them with 4T1 cancer cells, fluorescence inside the cells surged within the first hour and plateaued by about six hours, while normal 3T3 cells took up far less material. In living mice bearing 4T1 tumors, the membrane-coated particles accumulated in tumors progressively after intravenous injection, peaking at twelve hours — at which point tumor fluorescence was a striking 73.27-fold higher than in mice injected with free dye. Crucially, a biodistribution comparison showed that particles coated with 3T3 membranes showed no tumor enrichment, demonstrating that the homing is specifically mediated by the tumor-cell membrane’s own adhesion molecules rather than by any generic membrane effect.

Once the particles arrive, the tumor’s own chemistry triggers the payload. The tumor microenvironment is weakly acidic, and this acidity dissolves MnO2. In vitro release experiments showed that at pH 7.4, mimicking blood, less than 20 percent of R848 escaped over twelve hours, but at pH 5.0 roughly 45 percent was released within the first half hour and about 77 percent within three hours. This pH-gated behavior means the adjuvant stays locked up during circulation and is dumped only where it is needed — inside the tumor.

The therapeutic logic then unfolds in several reinforcing layers. MnO2 catalyzes the decomposition of hydrogen peroxide, which tumors overproduce, into oxygen, directly relieving the hypoxia that makes tumors resistant to radiation. Under X-ray irradiation, the released manganese ions amplify reactive oxygen species generation and deplete glutathione, the cell’s antioxidant shield. In cultured 4T1 cells treated with a 6 Gy radiation dose, the combination reduced viability by roughly 20 percent beyond radiation alone, produced the strongest signals of DNA double-strand breaks as measured by gamma-H2AX staining, and drove the highest levels of apoptosis. Immunohistochemical staining of treated tumors for HIF-1alpha, a master regulator of the hypoxic response, was markedly reduced in mice receiving the full combination, confirming that hypoxia relief operates in vivo as well.

Radiation’s second, subtler gift is immunogenic cell death, in which dying tumor cells hoist danger flags — calreticulin on their surface, and ATP and HMGB1 released outside — that alert the immune system. The combination of MnO2–R848@CM and radiation produced the greatest calreticulin translocation, the lowest residual nuclear HMGB1, and the highest ATP release in cultured cells. These damage signals then act on dendritic cells, the sentinels of adaptive immunity. In mouse bone-marrow-derived dendritic cells, MnO2 alone raised maturation marker expression (CD80/CD86) from 59.2 to 76.2 percent, R848 alone to 78.0 percent, and the combination performed even better, while also driving robust secretion of the inflammatory cytokine TNF-alpha. In a Transwell system separating irradiated tumor cells from dendritic cells, the full combination pushed dendritic cell maturation to 77.5 percent, far above radiation alone. Mechanistically, manganese ions are known to accelerate the DNA-sensing enzyme cGAS and strengthen the binding of its product, cGAMP, to the STING adaptor, triggering type I interferon production — a pathway the team confirmed was activated in the treated dendritic cells.

The in vivo results were dramatic. In 4T1 tumor-bearing mice given a single injection followed by three radiation sessions, the membrane-coated platform combined with radiation achieved a tumor growth inhibition rate of 92.30 percent, with some mice showing complete tumor ablation. Tumor sections revealed the most extensive necrosis, the most apoptotic cells, and the strongest suppression of the proliferation marker Ki67 in the combination group, and immunofluorescence showed the greatest infiltration of CD8-positive cytotoxic T cells — the effector arm that can recognize tumor antigens and kill malignant cells throughout the body. Safety profiles were reassuring: treated mice maintained stable body weight, blood chemistry markers of liver and kidney function showed no significant deviations, and histology of major organs revealed no pathological changes or inflammatory infiltration.

The authors are candid about the work’s limits and its promise. They observed a degree of what they call synergistic overflow, in which the fully combined treatment did not always deliver benefit clearly beyond its individual components while adding preparation complexity, and they note that the tumor membrane itself may carry adjuvant properties that remain to be explored. They also point toward the clinic’s hardest problem: primary resistance to immune checkpoint inhibitors. By relieving hypoxia, inducing immunogenic cell death, activating cGAS–STING, and ferrying R848 into tumors to mature dendritic cells and recruit CD8-positive T cells, the platform could, in principle, convert immunologically cold tumors into hot ones and sensitize them to anti-PD-1 or anti-PD-L1 therapy — a hypothesis the team plans to test directly. For now, the study stands as a vivid demonstration that a nanoparticle wearing a tumor’s own face can carry an immune alarm clock deep into hostile territory, set it to go off under radiation, and leave the immune system to finish the job.

Subject of Research: A cancer-cell-membrane-coated MnO2 nanoplatform delivering the R848 adjuvant to enhance radio-immunotherapy of breast cancer

Article Title: Cancer-cell-mimicking MnO 2 nanoplatform delivers immunological adjuvants to enhance radio-immunotherapy

Article References: Zhang, Z., Liu, P., Zeng, W., Huang, C., Wang, S., Guan, S., Duan, Y., Wu, D., Zhao, Y., & Wu, J. (2026). Cancer-cell-mimicking MnO2 nanoplatform delivers immunological adjuvants to enhance radio-immunotherapy. Materials Today Bio, 41, Article 103720. https://doi.org/10.1016/j.mtbio.2026.103720

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103720

Keywords: MnO2 nanosheets, cancer cell membrane coating, R848, radio-immunotherapy, cGAS-STING pathway, immunogenic cell death, tumor hypoxia, dendritic cell maturation, CD8 T cells, breast cancer, biomimetic nanoparticles, drug delivery

The central obstacle the researchers set out to overcome is a vicious cycle linking low oxygen to drug resistance. Solid tumors, especially aggressive ones like triple-negative breast cancer, are chronically starved of oxygen because their hastily built blood vessels are irregular and dysfunctional. Oxygen can only diffuse about 100 to 200 micrometers from a functioning vessel, leaving tumor cores severely hypoxic. In this oxygen-poor environment, a transcription factor called hypoxia-inducible factor-1 alpha, or HIF-1α, becomes stabilized and switches on genes for ATP-binding cassette transporters—most notably P-glycoprotein, the efflux pump encoded by ABCB1. P-glycoprotein literally pumps chemotherapeutics like paclitaxel back out of the cell, rendering them useless. Blood transfusions and hyperbaric oxygen therapy can ease systemic hypoxia, but neither reliably relieves hypoxia inside the tumor itself.

Previous attempts to solve this problem have used hemoglobin-based oxygen carriers, since hemoglobin is the body’s natural oxygen transporter and can also catalyze the generation of reactive oxygen species. But free hemoglobin degrades rapidly, is dose-dependently toxic, and provokes systemic inflammation. Liposome-encapsulated hemoglobin improves stability, yet conventional formulations lack spatial precision, often pooling in the liver and spleen. The new study, led by Xunyi You and colleagues with senior author Ye Cao, took a different route: rather than relying on passive accumulation, the team attached their drug-loaded liposomes loosely to the surfaces of intact red blood cells—a strategy known as RBC hitchhiking.

The concept is elegantly physical. The liposomes bind to red blood cells through weak, reversible interactions such as van der Waals forces and electrostatic attraction, without being internalized. When the cell-liposome complexes are injected intravenously, they travel through the bloodstream until they squeeze through narrow capillaries. The shear forces in these tight passages mechanically scrape the nanoparticles off the red cell surfaces and transfer them to the capillary endothelium, dramatically increasing accumulation in the first capillary-rich organ downstream of the injection site. For drugs injected into a tail vein, that organ is the lung—precisely where triple-negative breast cancer metastasizes. The team’s earlier work had already shown that combining liposomes with RBC hitchhiking extends blood half-life and boosts pulmonary accumulation.

Building on that foundation, the researchers formulated liposomes from the phospholipid DPPC, the pH-sensitive lipid DOPE, and cholesterol, encapsulating both paclitaxel and purified hemoglobin in a single nanoparticle. The resulting LEHP particles measured between 100 and 200 nanometers in diameter with a polydispersity index below 0.2, indicating a highly uniform population, and transmission electron microscopy confirmed smooth, spherical structures. Paclitaxel encapsulation efficiency was 83.32 percent for hemoglobin-free liposomes and 58.27 percent for the hemoglobin-loaded version, the reduction likely reflecting the protein occupying space in the aqueous core. Critically, the hemoglobin inside LEHP showed a P50 of about 10.20 mmHg—substantially lower than the roughly 26.5 mmHg of normal adult hemoglobin—meaning a left-shifted oxygen dissociation curve and enhanced oxygen loading in the pulmonary circulation, with favorable release under the low-oxygen conditions of the tumor.

The hitchhiking step itself proved remarkably gentle on the carrier cells. After optimizing the ratio of liposomes to red blood cells, confocal microscopy showed liposomes uniformly coating the erythrocyte membranes while preserving their native biconcave disc shape. The engineered cells maintained their CD47 expression—the “don’t eat me” signal that prevents clearance by the immune system—showed no significant increase in phosphatidylserine exposure, retained normal osmotic fragility profiles, and kept their deformability index unchanged, preserving the mechanical flexibility needed to squeeze through splenic sinuses and lung capillaries.

Inside tumor cells, the payload executes a coordinated attack on two fronts. First, delivered hemoglobin alleviates hypoxia, which destabilizes HIF-1α and removes the transcriptional activation of ABCB1, sharply downregulating P-glycoprotein and restoring the cell’s vulnerability to paclitaxel. Second, the iron released from hemoglobin fuels the Fenton reaction, converting hydrogen peroxide into highly reactive hydroxyl radicals. The team documented the three hallmarks of ferroptosis—an iron-dependent form of cell death driven by lipid peroxidation: elevated labile ferrous iron, surging lipid peroxides, and a collapse of mitochondrial membrane potential. Molecular analysis showed LEHP suppressing the antioxidant guardian GPX4 and its regulator Nrf2 along with the cystine transporter SLC7A11, while upregulating the transferrin receptor, driving NCOA4-mediated ferritinophagy to liberate stored iron, and boosting ACSL4 to supply polyunsaturated fatty acid substrates for membrane oxidation. When cells were pretreated with ferrostatin-1, a specific ferroptosis inhibitor, LEHP-induced cell death was profoundly reversed—confirming ferroptosis as the dominant killing mechanism, with a minor complementary contribution from apoptosis at high drug concentrations.

The DOPE lipid added a self-amplifying delivery trick. In the acidic lysosome, DOPE destabilizes membranes and releases hemoglobin; the liberated ferrous iron then generates radicals that attack the polyunsaturated fatty acids concentrated in the lysosomal membrane itself. That peroxidation increases membrane permeability, accelerating the escape of both hemoglobin and paclitaxel into the cytosol—a ROS-dependent positive feedback loop that the team observed as early as two hours after treatment. The researchers describe the net effect as “re-oxygenation injury”: chronically hypoxic cells, adapted to survive without oxygen, are suddenly overwhelmed by an oxygen influx that their antioxidant defenses cannot absorb, triggering a catastrophic oxidative collapse.

In vivo, the advantages compounded. In mice bearing 4T1 breast cancer lung metastases, RBC-hitchhiked liposomes produced a 2.7-fold increase in pulmonary fluorescence intensity and a 4.6-fold improvement in the lung-to-liver ratio compared with liposomes alone, with lung signals persisting up to 48 hours. In the therapeutic experiment, paclitaxel monotherapy failed to arrest tumor progression, and each partial strategy—hemoglobin without hitchhiking, or hitchhiking without hemoglobin—fell short on its own. Only the fully integrated RBC-LEHP platform achieved sustained regression: at the day 13 endpoint, pulmonary bioluminescence in the RBC-LEHP group was (7.70 ± 2.86) × 10⁴, roughly three orders of magnitude below the LEP group’s (2.19 ± 0.37) × 10⁷. Histology showed intact bronchial architecture and no edema or fibrosis in treated lungs, with no systemic toxicity in the heart, liver, spleen, or kidneys, and reduced Ki67 proliferation, CD31-marked microvessel density, and MMP2 and MMP9 metastasis markers.

Perhaps most strikingly, the treatment remodeled the tumor immune microenvironment, markedly increasing infiltration of CD4-positive and CD8-positive T cells and shifting the lung tumors from an immunologically cold state toward an inflamed, hot one. High-throughput proteomics of lung tissue confirmed the mechanism at the systems level: NCOA4 upregulation and GPX4 downregulation enforcing ferroptotic commitment, HIF-1α and P-gp suppression restoring chemosensitivity, and suppression of the epigenetic driver EZH2 and the pro-survival factor CEBPB dismantling the tumor’s transcriptional survival programs. The authors caution that some hepatic accumulation was observed at 24 hours, though without histological signs of liver damage, and that systemic immune responses in peripheral lymphoid organs remain to be profiled. Still, the study establishes a compelling template—targeted delivery, hypoxia alleviation, ferroptosis plus chemotherapy, tumor suppression—that could extend beyond breast cancer to any malignancy whose resistance is rooted in the oxygen-starved depths of the tumor.

Subject of Research: A biomimetic erythrocyte-hitchhiking liposome system delivering hemoglobin and paclitaxel to overcome hypoxia-driven chemoresistance in triple-negative breast cancer lung metastasis via ferroptosis

Article Title: Oxygen-augmented erythrocyte-liposome hybrids to overcome paclitaxel resistance in triple-negative breast cancer metastasis via enhanced ferroptosis

Article References: You, X., Zhu, K., Li, W., Wang, H., Zhong, R., Li, S., Liu, J., Wong, Y. S., Venkatraman, S. S., & Cao, Y. (2026). Oxygen-augmented erythrocyte-liposome hybrids to overcome paclitaxel resistance in triple-negative breast cancer metastasis via enhanced ferroptosis. Materials Today Bio, 41, Article 103705. https://doi.org/10.1016/j.mtbio.2026.103705

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103705

Keywords: triple-negative breast cancer, ferroptosis, red blood cell hitchhiking, liposomes, tumor hypoxia, HIF-1alpha, P-glycoprotein, paclitaxel, drug resistance, lung metastasis, hemoglobin, nanomedicine

A team of researchers led by Jie Gao, Wen-Chao Geng, and Zeli Yuan, publishing in Materials Today Bio, has now unveiled a nanoplatform that tackles both of the fundamental bottlenecks of hypoxia-activated chemotherapy at once. Their system, called CL-Azo-CPT/Ce6 NPs, does not merely wait passively for endogenous hypoxia to activate the drug. Instead, it actively amplifies the oxygen starvation using light, and then reports in real time, through its own chemiluminescent glow, exactly how much drug has been released inside the tumor. The authors describe this integrated behavior as a Sense-Amplify-Report cycle, and the design represents a rare example of a therapeutic formulation that can measure its own activation while it is happening inside a living animal.

The molecular heart of the platform is a chemiluminescent prodrug named CL-Azo-CPT. It is built around Schaap’s adamantylidene-1,2-dioxetane, a luminophore famous for the persistent glow it emits when destabilized, and it is connected to the anticancer payload camptothecin through a self-immolative carbonate spacer and an azobenzene trigger. The azobenzene linkage is the gatekeeper: it is cleaved selectively by azoreductase enzymes, whose activity rises sharply under hypoxic conditions. Once the azo bond is cut, a spontaneous self-immolative cascade unfolds, simultaneously liberating camptothecin and unmasking the dioxetane luminophore. Because a single activation event produces both the drug and a photon, the light output is stoichiometrically coupled to drug release. In solution experiments, the researchers demonstrated a nearly perfect linear correlation between chemiluminescence intensity and the amount of camptothecin released, quantified independently by high-performance liquid chromatography, with a correlation coefficient of 0.997.

The optical performance of the prodrug is equally impressive. Upon exposure to sodium dithionite, a chemical mimic of azoreductase activity, CL-Azo-CPT produced a broad emission spanning 430 to 650 nanometers with a peak at 515 nanometers, roughly a ninety-fold enhancement over the background signal of the intact molecule. The signal rose to its maximum within five minutes and decayed with a half-life of eighteen minutes, kinetics well suited to dynamic monitoring. Selectivity testing against a battery of biologically relevant species, including metal ions, amino acids, glutathione, hydrogen peroxide, reducing agents, and digestive enzymes, confirmed that only azo reduction elicited a strong response. The intact azobenzene moiety efficiently quenches the dioxetane emission, so no appreciable glow appears until the hypoxia trigger has actually fired, keeping the background noise low.

Crucially, chemiluminescence requires no external excitation light. Unlike fluorescence imaging, which demands a laser or lamp that also excites endogenous molecules and generates tissue autofluorescence, chemiluminescence emerges from the chemical reaction itself. This gives it an exceptionally high signal-to-noise ratio in living tissue, where autofluorescence often buries weak fluorescent signals. For a reporter intended to track drug activation deep within a tumor microenvironment, that excitation-free property is not a luxury but a necessity, and it is one of the main reasons the authors chose a dioxetane scaffold rather than a conventional fluorophore.

To add the amplification step, the researchers co-encapsulated CL-Azo-CPT with chlorin e6, a well-known photosensitizer, inside PEGylated DSPE-mPEG2000 nanoparticles prepared by thin-film hydration. The resulting particles measured about 169 nanometers in hydrodynamic diameter with a polydispersity index of 0.22, showed uniform spherical morphology by electron microscopy, and remained colloidally stable for a week in buffer. Encapsulation efficiencies were high, at roughly 97 percent for the prodrug and 65 percent for the photosensitizer. When illuminated with white light, the encapsulated chlorin e6 generated singlet oxygen, confirmed by the rapid decay of the indicator dye ABDA, proving that co-encapsulation did not impair its photodynamic activity. That activity comes with a built-in consequence: every photon-driven reaction consumes molecular oxygen, so photodynamic therapy actively deepens the very hypoxia that the prodrug needs in order to activate.

Cellular experiments in CT26 colon carcinoma and HCT116 colorectal cancer cells mapped out each element of the cascade. Under chemically induced hypoxia, intracellular fluorescence from released camptothecin and the MCCH reporter climbed steadily over six hours, while remaining weak in well-oxygenated cells, and chemiluminescence signals increased with both time and drug concentration. Cytotoxicity assays under a four-condition matrix of oxygen status and light exposure revealed the logic of the design clearly. In the dark under normoxia, the nanoparticles were essentially harmless, confirming that the drug stayed caged and the photosensitizer stayed quiet. Under hypoxia alone, moderate killing demonstrated the Sense module, with the prodrug responding to endogenous low oxygen. Under light alone, photodynamic killing occurred but was weakened by oxygen deprivation. Only when hypoxia and light were combined did the full formulation achieve its lowest IC50 values, 3.0 micromolar in CT26 cells and 2.6 micromolar in HCT116 cells, along with near-complete cell ablation in live-dead staining.

The in vivo results were the most striking. In mice bearing subcutaneous 4T1 tumors, endogenous hypoxia alone produced a chemiluminescent response that peaked about fifty minutes after intratumoral injection. When the tumors were irradiated, the signal shifted to a later but substantially stronger maximum at 110 minutes, with peak intensity 1.69-fold higher and integrated signal 1.86-fold higher than in non-irradiated tumors, while normal tissue showed consistently weak signals. In a CT26-Luc1 peritoneal metastasis model, intraperitoneal injection of the nanoparticles produced a distinct glow that peaked at fifteen minutes in tumor-bearing mice and was undetectable in healthy animals, with ex vivo imaging confirming that the emission localized to intestinal tumor nodules. Because the chemiluminescent output is coupled to drug release, these images amount to a real-time, semi-quantitative map of where and when the chemotherapy is actually being deployed, though the authors caution that tissue absorption and scattering make the in vivo signal a relative rather than absolute measure.

Therapeutically, the platform delivered decisive results in the peritoneal metastasis model. Seventy tumor-bearing mice were divided into seven treatment groups receiving four intraperitoneal doses over fourteen days, with light-treated groups receiving abdominal illumination after each injection. Mice given saline or photosensitizer alone all died within fifteen days, and chemotherapy-containing groups without light extended survival only marginally, with all animals dying within twenty days. Photodynamic therapy alone prolonged survival to roughly twenty-five days, but the combined CL-Azo-CPT/Ce6 nanoparticles with light performed best, with one mouse surviving beyond day thirty. At the endpoint, the combined treatment produced the lowest ascites volume, the smallest tumor nodules, the highest apoptotic index at 72.81 percent by TUNEL staining, and the lowest proliferative fraction at 2.84 percent by Ki-67 staining. Serum biochemistry showed that liver stress markers, elevated in all other tumor-bearing groups, returned to healthy-control levels in the combined-treatment group, and histology of major organs revealed no off-target damage.

The authors are careful to frame the platform honestly. The current formulation is feedback-guided rather than fully closed-loop: the chemiluminescent readout can inform decisions about subsequent light dosing, but automated real-time adjustment of treatment remains a goal for future work. They also note that because chlorin e6 is excited at approximately 654 nanometers and light penetrates tissue only shallowly, the strategy is best suited to superficially accessible tumors, intraperitoneal lesions amenable to laparoscopic or intraoperative illumination, or gastrointestinal lesions reachable by endoscopy, exactly the settings modeled in their peritoneal carcinomatosis study. There is also a subtler consideration: excessive or sustained hypoxia can, in principle, promote tumor invasiveness and immunosuppression, so the self-reporting design offers a way to titrate light exposure within a therapeutic window, stopping once the readout indicates adequate activation. Even with those caveats, the work establishes a compelling framework for next-generation precision nanomedicines, one in which the treatment does not just attack the tumor microenvironment but watches itself do it, photon by photon.

Subject of Research: A self-reporting chemiluminescent nanoplatform coupling photodynamic hypoxia amplification with hypoxia-activated prodrug therapy for precision cancer treatment

Article Title: Coupling photodynamic hypoxia amplification with a self-reporting chemiluminescent prodrug for adaptive precision therapy

Article References: Gao, J., Wei, L., Wang, Y., Yang, M., Wu, Y., Geng, W.-C., & Yuan, Z. (2026). Coupling photodynamic hypoxia amplification with a self-reporting chemiluminescent prodrug for adaptive precision therapy. Materials Today Bio, 41, Article 103712. https://doi.org/10.1016/j.mtbio.2026.103712

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103712

Keywords: hypoxia-activated prodrug, chemiluminescence, photodynamic therapy, nanoparticles, camptothecin, chlorin e6, tumor microenvironment, theranostics, peritoneal metastasis, azoreductase, dioxetane, precision medicine

The rationale for the approach lies in the peculiar biology of glioblastoma. These tumors are notoriously oxygen-starved because their blood vessels are underdeveloped and chaotic. That hypoxia activates hypoxia-inducible factor 1, or HIF-1, a master transcription factor that drives angiogenesis, metabolic reprogramming, and drug resistance by upregulating efflux pumps. Photodynamic therapy, which uses a photosensitizer and light to generate reactive oxygen species that destroy tumor cells, makes the problem worse: it consumes oxygen and damages tumor microvessels, deepening the hypoxia and paradoxically boosting HIF-1 activity. Photothermal therapy, which kills cells with heat, triggers its own countermeasure in the form of heat shock proteins, particularly HSP70, which help tumor cells survive thermal stress and develop thermoresistance.

To exploit light-based therapy despite these obstacles, the team first optimized the ratio of IR780 to paclitaxel inside bovine serum albumin nanoparticles. Using the combination index method, a standard quantitative tool for drug synergy, they found that a 1:2 ratio of IR780 to paclitaxel yielded a combination index of 0.39, well below the threshold of 1 that indicates true synergism. The resulting nanoparticles measured roughly 168 nanometers in hydrodynamic diameter by dynamic light scattering, with polydispersity indices around 0.1, indicating a highly uniform population. Transmission electron microscopy revealed spherical particles of approximately 120 nanometers. Encapsulation efficiency was high, at 89.8 percent for IR780 and 84.4 percent for paclitaxel, and the particles remained colloidally stable for at least 72 hours at room temperature.

The photophysical performance of the encapsulated dye proved markedly superior to the free drug. Under 808-nanometer near-infrared irradiation, free IR780 raised solution temperature by about 18 degrees Celsius within five minutes before its effect collapsed, a consequence of photobleaching. The albumin-encapsulated version, by contrast, generated roughly 25 degrees of heating and sustained it for at least ten minutes without decline. The nanoparticles also withstood at least four heating-cooling cycles, while free IR780 survived only one. Ultraviolet-visible spectroscopy showed a red shift in the dye’s absorption peak from 770 to about 790 nanometers, attributed to molecular aggregation within the particles, which improved excitation at 808 nanometers. Reactive oxygen species generation, measured with the chemical probe DPBF, was equally robust, and adding paclitaxel did not diminish the dye’s photodynamic output.

In LN229 human glioma cells, the nanoparticles were taken up faster than free IR780, and the team traced the mechanism to albumin-specific pathways. Pretreating cells with free albumin competitively blocked nanoparticle internalization in a concentration-dependent manner, consistent with uptake mediated by proteins such as SPARC and gp60, both overexpressed in glioblastoma. Once inside, the nanoparticles localized to lysosomes, where near-infrared irradiation disrupted lysosomal membranes, as shown by acridine orange staining, facilitating the escape and release of paclitaxel. Irradiated cells loaded with the nanoparticles heated about 15 degrees Celsius in four minutes, compared with roughly 10 degrees for free dye, and produced visibly more reactive oxygen species.

But the irradiation also exposed the therapy’s Achilles heel. A hypoxia-sensitive fluorescent probe revealed that photodynamic treatment significantly increased oxygen deprivation in the cells, and western blotting showed HIF-1α expression rising by 56 percent after irradiation. Under simulated hypoxia, the potency of both phototherapy and chemotherapy dropped substantially: the half-maximal inhibitory concentration of the combined nanoparticles rose from 0.08 to 0.48 micrograms per milliliter of IR780 equivalent. This is precisely where acriflavine entered the picture. When added to the treatment, the drug, which binds the HIF-1α subunit and prevents its dimerization with HIF-1β, further reduced the inhibitory concentrations to 0.32 and 0.63 micrograms per milliliter for IR780 and paclitaxel respectively under hypoxic conditions, and drove apoptosis, measured by cleaved caspase-3, to its highest levels.

The most striking discovery came when the team examined heat shock protein expression. Acriflavine alone suppressed HSP70 by roughly 80 percent compared with controls, and when combined with the nanoparticles it brought HSP70 levels down even under photothermal stress. To the authors’ knowledge, this is the first report of acriflavine acting as a potent HSP70 inhibitor, meaning a single molecule simultaneously blocks the hypoxia response that undermines photodynamic therapy and the thermoresistance that blunts photothermal therapy. The combination also nearly abolished glioma cell migration and invasion in scratch and Transwell assays, an effect the researchers linked to acriflavine’s suppression of HIF-1 downstream targets including VEGF, GLUT-1, and MMP9, proteins that drive angiogenesis, glucose uptake, and metastasis.

In tumor-bearing mice, the nanoparticles accumulated preferentially in tumors after intravenous injection, peaking at 24 hours, while free IR780 showed far weaker tumor localization. Acriflavine was delivered differently: because it is highly water-soluble and clears quickly from the body, the team embedded it in sodium alginate that gels on contact with the physiological calcium found inside tumor tissue, releasing the drug for at least 72 hours. In the treatment study, nanoparticles plus acriflavine hydrogel under near-infrared irradiation suppressed tumor growth by essentially 100 percent from day six onward, and three of five mice in that group showed complete tumor elimination. Histology confirmed the most extensive cellular destruction and the highest apoptotic fractions in the combination group. Tumors heated by 17 degrees Celsius within five minutes of irradiation, and HSP70 expression in treated tumors fell below even the untreated control level.

Safety signals were encouraging. Body weights remained stable across all treatment groups, organ histology showed no lesions, hemolysis stayed below 5 percent even at high nanoparticle concentrations, and blood chemistry markers of liver and kidney function showed no significant differences between treated and control animals. The authors are candid about limitations: the efficacy studies used a subcutaneous model rather than an orthotopic brain tumor, which lacks the blood-brain barrier and invasive growth patterns of real glioma, and the two delivery systems remain separate formulations. Still, both platforms have clinical precedents, from the FDA-approved albumin-paclitaxel formulation Abraxane to carmustine wafers implanted in post-surgical brain cavities. By showing that one repurposed, clinically approved dye can neutralize both HIF-1 signaling and heat shock defenses at once, the study offers a compelling template for reinforcing combination therapy in hypoxic, treatment-resistant tumors.

Subject of Research: Albumin nanoparticle photochemotherapy with acriflavine-mediated HIF-1 and HSP70 inhibition for glioma treatment

Article Title: Acriflavine-empowered IR780-PTX albumin nanoparticles for reinforced synergistic photochemotherapy

Article References: Li, D., Wang, T., Liu, H., Yao, Y., Lu, T., Wang, R., Jiang, X., Zhang, X., Sun, M., Peng, Y., Yang, Y., Shao, N., Ding, D., & Zhi, F. (2026). Acriflavine-empowered IR780-PTX albumin nanoparticles for reinforced synergistic photochemotherapy. Advanced Biotechnology, 4(1), Article 10. https://doi.org/10.1007/s44307-026-00097-9

Image Credits: AI Generated

DOI: 10.1007/s44307-026-00097-9

Keywords: glioblastoma, albumin nanoparticles, photothermal therapy, photodynamic therapy, paclitaxel, IR780, acriflavine, HIF-1, HSP70, tumor hypoxia, drug delivery, combination therapy

The central concept guiding this research is the tumor microenvironment, or TME, the scaffold of extracellular matrix within which tumor cells and host immune cells communicate and compete. Many cancers are described as immunologically cold, meaning they contain few functional cytotoxic immune cells and resist the effects of immune checkpoint inhibitors, the landmark therapies that block inhibitory receptors such as PD-1 and PD-L1 to unleash CD8-positive T cells. Checkpoint inhibitors have transformed survival for many patients since emerging in the 1990s, but their efficacy is throttled by features of the TME, including low T cell numbers, T cell exhaustion, oxygen-starved tissue, and dense populations of immunosuppressive cells. The review’s authors, led by Campbell M. Johnston and Hongji Zhang of the University of Virginia’s Department of Surgery, argue that exercise directly counters many of these barriers, effectively warming cold tumors and sensitizing them to drugs that were previously powerless against them.

One of the most detailed lines of evidence concerns tumor-associated macrophages, or TAMs, immune cells that are abundant within cold tumors and frequently promote malignancy. TAMs exist along a spectrum from the M1 phenotype, which fights tumors, to the M2 phenotype, which secretes immunosuppressive molecules such as interleukin-4, interleukin-10, PD-L1, and transforming growth factor-beta that blunt effector T cell function and empower regulatory T cells. Worse, TAMs can push CD8-positive T cells into a terminally exhausted state from which they cannot recover, and hypoxia accelerates this process. In mouse models of glioblastoma, depleting TAMs increased the proportion of stem-like progenitor-exhausted T cells and improved responsiveness to anti-PD-1 therapy, underscoring how central these cells are to treatment failure. Preclinical studies now show that aerobic exercise can tip the balance, repolarizing macrophages from the pro-tumor M2 state toward the anti-tumor M1 state and reducing total M2 numbers within tumors.

The macrophage data are remarkably consistent across exercise modalities. Breast cancer-bearing mice that ran on treadmills before and after tumor inoculation showed fewer M2 macrophages within their tumors, while medium-intensity treadmill running increased the M1-to-M2 ratio in similar models. In melanoma-inoculated mice, swimming prevented M2 polarization and reduced interleukin-6 production, inhibiting tumor glycolysis and lowering lactic acid accumulation. Exercise also increased the production of major histocompatibility complex class II molecules on macrophages, sharpening their ability to activate T cells. These findings matter clinically because pharmacological strategies targeting macrophage biology, including inhibitors of transforming growth factor-beta, have struggled in human trials, failing to show clear benefit or producing severe adverse events. Exercise, by contrast, achieves a similar biological reprogramming without toxicity, offering a route around a therapeutic bottleneck that has frustrated drug developers.

Myeloid-derived suppressor cells, or MDSCs, represent a second immunosuppressive population that exercise appears to tame. These cells promote immune evasion by impairing chemokine secretion, recruiting regulatory T cells, and increasing PD-1 expression on T cells. Multiple preclinical studies show that physical activity delays MDSC accumulation and reduces their numbers within tumors. Mice exercised before and after breast carcinoma inoculation had significantly lower intratumoral MDSC levels than sedentary controls, and treadmill running started after tumor inoculation reduced splenic MDSCs, slowed tumor progression, and increased immune cell infiltration in mammary carcinoma models, with an inverse relationship between MDSC abundance and CD8-positive T cell presence. Crucially, these findings extend to humans. In newly diagnosed breast cancer patients, a single session of acute exercise increased natural killer and CD8-positive T cell levels while reducing MDSCs. In esophageal cancer patients who exercised during neoadjuvant chemotherapy, CD8-positive T cell counts rose while inflammatory biomarkers associated with MDSCs and TAMs fell significantly.

Hypoxia and disordered blood vessel growth form a third pillar of the exercise-immunotherapy connection. Tumors grow so erratically that their vasculature becomes tangled and inefficient, starving tissue of oxygen and stabilizing hypoxia-inducible factors that drive further abnormal angiogenesis. The resulting hypoxic environment excludes natural killer and CD8-positive T cells, inhibits dendritic cells and antigen presentation, recruits immunosuppressive cells, and pushes macrophages toward the pro-tumor M2 phenotype through a CXCL8-interleukin-10 signaling axis, all of which correlate with poor prognosis and resistance to checkpoint blockade. Exercise directly counters this vicious cycle. Melanoma-bearing mice that swam at low or moderate intensity showed significantly reduced expression of hypoxia and glycolysis genes, along with greater CD8-positive T cell infiltration and cytotoxicity. Daily high-intensity exercise lowered intratumoral hypoxic fractions in breast carcinoma models, and in a landmark clinical observation, pancreatic cancer patients who exercised during preoperative therapy showed increased tumor vascularity, while exercised mice bearing patient-derived pancreatic tumors displayed vascular remodeling, accelerated regression, and delayed regrowth.

Natural killer cells, the innate immune system’s front-line tumor killers, emerge as perhaps the cells most responsive to exercise. NK cells mobilize more readily into tumors in exercised animals, and work by Cho and colleagues showed that NK cells from exercised individuals kill target cells more efficiently, with their cytotoxicity actually enhanced under hypoxic conditions, a striking advantage given the oxygen-poor nature of tumors. This resilience stems from exercise-induced metabolic reprogramming that reduces mitochondrial oxidative stress and, through interleukin-15 signaling, lessens sensitivity to reactive oxygen species such as hydrogen peroxide within the tumor microenvironment. Clinical translation is already visible: men with localized prostate cancer who adhered strictly to high-intensity interval training showed significantly increased NK cell infiltration into their tumors. Perhaps most dramatic, Pedersen and colleagues found that voluntary wheel running reduced tumor volume by 66 percent in mice lacking functional T cells, an effect abolished when NK cell production was blocked, proving that NK cells alone can mediate exercise-driven tumor suppression.

CD8-positive T cells, the primary targets of checkpoint inhibitors, are recruited into exercised tumors through well-defined molecular routes. The chemokine receptor CXCR3, which binds CXCL9, CXCL10, and CXCL11, guides these cells into tumor tissue, and CXCR3 knockout mice show reduced T cell infiltration and blunted responses to PD-1 blockade. Recent work demonstrated that four weeks of preoperative treadmill running increased CXCL9 release and CXCR3-positive T cell recruitment in colorectal liver metastases, an effect lost in CXCL9-deficient mice. Exercise also suppresses CCL5, a chemokine that recruits regulatory T cells, TAMs, and MDSCs and correlates with poor prognosis, while boosting interleukin-15, a cytokine essential for T cell survival that appears to actively shift CD8-positive cells from circulation into tumors rather than merely raising their blood counts.

The combination studies provide the most compelling case. Melanoma-bearing mice treated with exercise plus anti-PD-1 therapy developed smaller tumors with more apoptotic cells, more cytotoxic T cells, and fewer regulatory T cells than mice receiving the drug alone. Similar synergy appeared in triple-negative breast cancer, where treadmill running improved therapeutic response, boosted T cell and NK cell activation, and cut MDSC numbers alongside anti-PD-1 treatment. In transgenic breast cancer models, adding running to anti-PD-1 therapy delayed tumor growth and improved control, even when both interventions began only after tumors reached a clinically relevant size. Pancreatic ductal adenocarcinoma, notoriously resistant to checkpoint inhibitors, responded to low-intensity treadmill running combined with anti-PD-1 when neither approach worked alone, an especially promising result for patients too ill for vigorous activity. Clinically, hepatocellular carcinoma patients who exercised regularly had significantly better overall and progression-free survival on combined lenvatinib and anti-PD-1 therapy, with matching results in mouse models. Randomized trials such as HI AIM and ERICA are now testing supervised exercise before and during immunotherapy infusions in lung cancer patients.

The authors are careful to note that clinical evidence remains limited and that major questions persist regarding optimal exercise modality, intensity, frequency, timing, and patient selection across cancer types, ages, sexes, disease stages, and body mass indices. Yet the biological coherence of the evidence is difficult to dismiss: exercise relieves hypoxia, normalizes vasculature, repolarizes macrophages, suppresses MDSCs and regulatory T cells, mobilizes NK cells, and drives cytotoxic T cells into tumors through defined chemokine axes, collectively converting cold tumors into inflamed, drug-responsive ones. If ongoing adequately powered trials with longitudinal immune profiling confirm these mechanisms in patients, structured physical activity could become one of the first universally accessible adjuncts to cancer immunotherapy, a prescription written not on a pharmacy pad but into the daily routines of patients fighting some of medicine’s most treatment-resistant cancers.

Subject of Research: How physical exercise modulates the tumor microenvironment to enhance cancer immunotherapy efficacy

Article Title: Physical Exercise in Immunotherapy

Article References: Johnston, C. M., Kim, S. J., Zhang, Y., Tsung, C., Kent, E., May, A., & Zhang, H. (2026). Physical Exercise in Immunotherapy. Sports Medicine – Open, 12(1), Article 130. https://doi.org/10.1186/s40798-026-01101-1

Image Credits: AI Generated

DOI: 10.1186/s40798-026-01101-1

Keywords: physical exercise, cancer immunotherapy, immune checkpoint inhibitors, tumor microenvironment, tumor-associated macrophages, myeloid-derived suppressor cells, natural killer cells, CD8 T cells, PD-1, tumor hypoxia, interleukin-15, cold tumors