CRBU · Caribou Biosciences, Inc.

The FDA's RMAT designation for CB-011 marks a significant regulatory milestone for Caribou Biosciences, recognizing the therapy's potential to address unmet needs in relapsed/refractory multiple myeloma through expedited development pathways, including eligibility for rolling reviews and accelerated approval. This builds on strong initial clinical data from the CaMMouflage phase 1 trial's dose escalation, where the 450x10^6 CAR-T cell dose was selected as the recommended dose for expansion based on robust efficacy in 12 BCMA-naïve patients: 92% overall response rate, 75% complete response or better, and 91% minimal residual disease negativity as of the September 24, 2025 cutoff. Safety data further support advancement, showing a manageable profile in 35 patients on the selected lymphodepletion regimen, with common treatment-emergent adverse events like neutropenia (80%) and anemia (60%), but no dose-limiting toxicities such as graft-versus-host disease or neurotoxicities. CB-011's immune cloaking strategy via B2M knockout and B2M-HLA-E fusion distinguishes it as the first such allogeneic CAR-T in the clinic, potentially enabling off-the-shelf access to overcome manufacturing delays limiting only 10% of U.S. MM patients from receiving autologous CAR-T. With dose expansion underway in both BCMA-naïve and exposed cohorts using 450x10^6 cells plus optimized lymphodepletion (500 mg/m² cyclophosphamide/30 mg/m² fludarabine x3 days), Caribou anticipates sharing initial expansion data and longer dose escalation follow-up in 2026, alongside FDA discussions on next steps. This positions CB-011 as a potential best-in-class option in a competitive landscape.