Marker Therapeutics, Inc. provided an update on the progress and clinical observations from the Phase 1 APOLLO study, with a data cutoff date of September 10, 2024. The Company?s Phase 1 APOLLO study is investigating MT-601, a multi-antigen recognizing (MAR) T cell product (formerly known as multi-tumor associated antigen-specific T cells, or multiTAA), in patients with lymphoma who have relapsed after anti-CD19 chimeric antigen receptor (CAR) T cell therapy or where anti-CD19 CAR-T cells are not an option. A total of 10 patients have been treated in the study, for which clinical data is currently available for 9 patients from 5 clinical sites across the United States.
Study participants showed early objective responses with and without lymphodepletion. However, immunomonitoring data confirmed that lymphodepletion enhanced the expansion and persistence of MAR-T cell clones in vivo. Key findings from the APOLLO study include: Safety: Infusion of MT-601 was well tolerated in all study participants, with no observation of immune-effector cell associated neurotoxicity syndrome (ICANS) and one reported Grade 1 cytokine release syndrome (CRS).
No dose limiting toxicities (DLTs) have been reported to date. Efficacy: In the first dose cohort, 7 out of 9 patients achieved objective responses (78%) at first response assessment, with 4 patients demonstrating complete response (CR; 44.4%). Time in Follow-Up: Long-term follow-up of 6 to 12 months is currently available for three patients.
Ongoing follow-up visits are being conducted to assess the durability of responses. All study participants are monitored closely to ensure comprehensive data collection and patient safety. Although CD19-targeting CAR-T cell therapies have gained acceptance as treatment for patients with lymphoma, 40-60% of patients relapse within the first year of treatment (Chong et al, N Engl J Med, 2021; Neelapu et al, Blood, 2023.).
These post-CD19 CAR-T relapsed patients currently have no approved standard of care, illustrating a high unmet medical need and urgency for new therapies. In addition, CAR-T cells are associated with severe side effects such as CRS or ICANS and may increase the risk for secondary malignancies (U.S. Food and Drug Administration, November 28, 2023). Data from clinical trials to date have demonstrated that MAR-T cells are well tolerated with no evidence of ICANS.
In addition, Marker?s non-engineered MAR-T cell approach selectively expands natural tumor-specific T cells from a patient?s blood that can recognize a broad range of tumor antigens, minimizing the risk of mutagenesis.
