Marker announces sustained complete response in patient treated with MT-601

Marker Therapeutics reported a clinical update on the APOLLO study. The Phase 1 APOLLO study is investigating MT-601, a multi-tumor associated antigen-specific T cell product, for the treatment of patients with lymphoma who have failed or are ineligible to receive anti-CD19 CAR T cell therapy. The Company previously reported first enrollment in the dose escalation stage of the Phase 1 trial. The patient had diffuse large B cell lymphoma and failed four prior lines of therapy, including anti-CD19 CAR T cell therapy. Marker reported in September that the study participant tolerated the treatment well without treatment-related adverse events and achieved a complete metabolic response eight weeks after the second infusion of MT-601. Marker reports today that six months following the initial treatment with MT-601 the study participant has maintained complete response to treatment. These clinical results are reinforced by non-clinical proof-of-concept data demonstrating that MT-601 has the potential to eradicate lymphoma cells resistant to anti-CD19 CAR T cells, highlighting the therapeutic potential of MT-601 in vitro/ Although CD19-targeting CAR T cell therapies have gained acceptance as treatment for patients with lymphoma, up to 60% of patients treated with CAR T therapies relapse within one year. This APOLLO study participant relapsed within 90 days after CAR T cell therapy, yet maintained a complete response for at least six months after treatment with MT-601, suggesting that MT-601 is more durable compared to CAR T cells in this study participant. CAR T cell therapies, which have known severe side effects such as neurotoxicity, are also currently being investigated by the FDA for the risk of potential induction of secondary cancers adding another layer of concern for patients and clinicians. Notably, multiTAA-specific T cell therapies have been well-tolerated in clinical trials, and Marker believes that multiTAA-specific T cells are a safe alternative to CAR T cells due to their non-genetically engineered approach that selectively expands tumor-specific T cells from a patient’s/donor’s blood without the risk of mutagenesis.