Io Therapeutics Reports Synergistic Activity of RXR Agonist IRX4204 with CAR-T Therapy in Multiple Myeloma
Key Insights
Io Therapeutics (search) presented preclinical data at ASH 2025 showing their RXR (search) agonist IRX4204 enhances BCMA (search) CAR-T cell persistence and anti-tumor function in multiple myeloma (search) models.
The compound protects CAR-T cells from ferroptosis-mediated cell death while simultaneously inducing ferroptosis in myeloma cells through distinct molecular mechanisms.
IRX4204 demonstrated synergistic efficacy when combined with both BCMA (search) CAR-T cells and lenalidomide, significantly improving tumor control and survival in xenograft models.
Io Therapeutics (search) presented compelling preclinical data at the 67th American Society of Hematology Annual Meeting demonstrating that their retinoid X nuclear receptor (RXR (search)) agonist IRX4204 enhances the efficacy of BCMA (search) CAR-T cell therapy in multiple myeloma (search) through a novel ferroptosis-modulating mechanism. The collaborative research with Duke University School of Medicine reveals a dual-action approach that protects therapeutic T-cells while targeting cancer cells.
Dual Mechanism Addresses CAR-T Therapy Limitations
The research, conducted under Professor Yubin Kang at Duke University, addresses a critical challenge in multiple myeloma (search) treatment. While BCMA (search) CAR-T therapy induces deep responses, most patients eventually relapse due to T-cell exhaustion, limited CAR-T persistence, and metabolic stress in the tumor microenvironment. The studies showed that activated T-cells are vulnerable to ferroptosis, a form of cell death driven by glutathione depletion, oxidative stress, and CHAC1 (search) activity.
IRX4204 demonstrated a protective effect on CAR-T cells by suppressing CHAC1 (search)-driven ferroptosis and activating PINK1/PARK2-mediated mitophagy, thereby preserving mitochondrial integrity. In vivo studies confirmed that IRX4204 improved tumor control and prolonged CAR-T persistence in multiple myeloma (search) xenografts.
Synergistic Anti-Tumor Activity
Simultaneously, IRX4204 promotes ferroptosis in multiple myeloma (search) plasma cells through a different pathway, activating the PPARα/RXRα-HMOX1 (search) axis and suppressing GPX4 (search)/SLC7A11-mediated antioxidant defense. This dual mechanism creates synergistic therapeutic effects when combined with established treatments.
The combination of IRX4204 and lenalidomide significantly reduced tumor growth compared to lenalidomide alone and prolonged median survival without increased systemic toxicity. Tumor analysis confirmed increased HMOX1 (search) and decreased GPX4 (search) expression in combination-treated mice, validating the proposed mechanism of action.
Biomarker Potential Identified
Bioinformatic analysis of multiple myeloma (search) patient datasets revealed that high HMOX1 (search) expression in plasma cells correlated with significantly improved overall survival (HR=0.51, p<0.001). Advanced-stage multiple myeloma plasma cells showed progressively lower HMOX1 levels, suggesting potential for biomarker-guided therapy selection.
Dr. Kang emphasized the clinical implications: "The data identify a druggable ferroptosis pathway in multiple myeloma (search) and provide a mechanistic rationale for combining RXR (search) agonists with established therapies including BCMA (search) CAR-T cells and lenalidomide. Our finding of a strong statistical correlation between HMOX1 (search) expression in patient plasma cells and survival of multiple myeloma patients suggests potential for biomarker-guided therapy selection."
Clinical Development Plans
IRX4204, invented by Chief Science Officer Vidyasagar Vuligonda, represents a next-generation RXR (search) agonist that more potently and selectively activates RXR compared to earlier compounds. The drug has demonstrated an excellent chronic dosing safety profile in clinical trials across lung, prostate, and other cancers, with anti-cancer activity observed in phase I and II trials for solid tumor malignancies.
CEO Martin E. Sanders highlighted the compound's clinical potential: "The IRX4204 safety profile likely will be suitable for chronic treatment of multiple myeloma (search) in combination with CAR-T cells and lenalidomide. The new findings that IRX4204 has synergistic efficacy against multiple myeloma with BCMA (search) CAR-T cells, and separately, also with a standard of care anti-myeloma drug lenalidomide, adds to the drug's scope of potential clinical utilities, and may result in increases of the proportions of multiple myeloma patients achieving cure or long-term maintenance of complete responses of their cancers."
The company plans to evaluate combinations of IRX4204 with CAR-T cells and lenalidomide in future clinical trials for multiple myeloma (search) patients, potentially addressing the current challenge that multiple myeloma remains incurable despite therapeutic advances.