Dr. Cowan and colleagues previously showed that treatment with a gamma secretase inhibitor increased BCMA expression on tumor cells and improved the efficacy of BCMA-targeted CAR T cells in a mouse model of multiple myeloma. The team also showed that a gamma secretase inhibitor could “markedly” increase the percentage of BCMA-positive tumor cells in myeloma patients (Blood. 2019 Nov 7;134[19]:1585-97).
To expand upon these findings, the researchers began a phase 1 trial of BCMA-directed CAR T cells and the oral gamma secretase inhibitor JSMD194 in patients with relapsed/refractory multiple myeloma.
Ten patients have been treated, five men and five women. The patients’ median age at baseline was 66 years (range, 44-74 years). They received a median of 10 prior therapies (range, 4-23). Nine patients had received at least one autologous stem cell transplant, and one patient had two. One patient underwent allogeneic transplant (as well as autologous transplant).
Three patients had received prior BCMA-directed therapy. Two patients had received BCMA-directed CAR T cells. One of them did not respond, and the other responded but relapsed. The third patient received a BCMA-targeted bispecific T-cell engager and did not respond.
Study treatment
Patients had BCMA expression measured at baseline, then underwent apheresis for CAR T-cell production.
Patients received JSMD194 at 25 mg on days 1, 3, and 5. Then, they received cyclophosphamide at 300 mg and fludarabine at 25 mg for 3 days.
Next, patients received a single CAR T-cell infusion at a dose of 50 x 106 (n = 5), 150 x 106 (n = 3), or 300 x 106 (n = 2). They also received JSMD194 at 25 mg three times a week for 3 weeks.