Marker Therapeutics, Inc. announced pre-clinical data from the Company's multiple tumor-associated antigens (multiTAA)-specific T cell product candidate MT-601 in lymphoma cells, including CD19 CAR T refractory cells. Although CAR T cell therapies targeting the CD19 antigen have gained acceptance as treatment for patients with relapsed/refractory lymphoma because of their significant benefit relative to the standard of care, up to 60% of patients treated with CAR T therapies relapse within a year (Chong EA et al, N Engl J Med, 2021). MultiTAA-specific T cell therapy was investigated in the Baylor TACTAL study, which enrolled patients with both Hodgkin's and non-Hodgkin's lymphoma (Vasileiou et al, J Clin Oncol, 2021).

The multiTAA-specific T cell product used in the TACTAL study was directed against five antigens and showed more durable clinical responses. Data from the TACTAL study has demonstrated that multiTAA- specific T cell products recognize cancer cells by up to five antigens presented on cancer cells and continue to kill even when cancer cells morph by downregulating the targeted antigen to escape recognition. Marker recently started to evaluate the safety and efficacy of MT-601, a multiTAA-specific T cells product that recognizes six antigens, including WT-1, a TAA that was not part of the targeted antigens in the TACTAL study, in patients with non-Hodgkin' lymphoma who have either relapsed after receiving anti-CD19 CAR T cell treatment or are eligible for anti-CD19 CAR T cells treatment.

Marker believes that killing induced by a product directed against six TAAs instead of five TAAs can potentially provide a more durable solution. Prior to starting the clinical trial Marker assessed the killing capacity of MT-601 in vitro in a lymphoma cell line and demonstrated that MT-601 kills lymphoma cells regardless of their CD19 expression levels.