The FDA has granted Regenerative Medicine Advanced Therapy (RMAT) designation to Poseida Therapeutics' P-BCMA-ALLO1, an investigational allogeneic CAR T-cell therapy, for the treatment of relapsed/refractory (R/R) multiple myeloma. This designation, announced September 16, 2024, highlights the therapy's potential to address the unmet needs of patients who have failed multiple prior lines of treatment. P-BCMA-ALLO1 is currently being evaluated in a phase 1/1b clinical trial (NCT04960579).
Promising Early Clinical Data
Early results from the ongoing phase 1 study of P-BCMA-ALLO1 have demonstrated promising efficacy and a favorable safety profile. Notably, the therapy offers quick, off-the-shelf access for patients. The study reported that P-BCMA-ALLO1 was well tolerated, with no instances of graft-vs-host disease (GVHD) observed across all dose levels. Furthermore, low rates of grade 1/2 cytokine release syndrome and neurotoxicity were reported among evaluable patients.
Updated findings from the phase 1 study are slated for presentation at the 21st International Myeloma Society Annual Meeting, with additional data expected in the latter half of 2024.
Management Perspective
"The RMAT designation for P-BCMA-ALLO1, our lead program, is based on impressive early clinical data from our ongoing phase 1 study and further validates its potential to address the unmet needs of patients with relapsed/refractory multiple myeloma," said Kristin Yarema, PhD, president and chief executive officer of Poseida Therapeutics. "Importantly, our data has shown clinical responses in very sick, refractory patients, including those that have received prior BCMA-targeted therapies. With both RMAT and orphan drug designations for P-BCMA-ALLO1, we look forward to working closely with the FDA as we continue to advance this next-generation, off-the shelf allogeneic CAR T therapy, including the recently initiated phase 1b portion of the trial."
Phase 1 Study Details
The ongoing phase 1 study is a multicenter, open-label, dose-escalation trial designed to evaluate the safety and efficacy of P-BCMA-ALLO1. The trial includes patients aged 18 years and older with prior exposure to BCMA-targeted therapies, including autologous BCMA CAR T-cell therapy and bispecific T-cell engagers. Key inclusion criteria include being at least 90 days post-autologous stem cell transplant (if performed), measurable myeloma, adequate organ function, and an ECOG performance status of 0 to 1. Patients must also have recovered from toxicities related to prior treatments.
The study's design incorporates a weight-based dose-escalation phase (part 1) following a 3+3 design, followed by administration at fixed doses (part 2). Patients undergo lymphodepletion before receiving P-BCMA-ALLO1 infusion, with a median of 7 days between enrollment and infusion. The study includes six cohorts.
The primary objectives of the study are to determine the safety and maximum tolerated dose of P-BCMA-ALLO1. Secondary endpoints include overall response rate (ORR), duration of response (DOR), time to response (TTR), progression-free survival (PFS), and overall survival (OS). The estimated primary completion date for the study is December 2027.
