Arcellx, Inc. announced new clinical data from its Phase 1 expansion study of CART-ddBCMA, now known as anitocabtagene autoleucel (anito-cel). Anito-cel utilizes a novel D-Domain BCMA binder that is compact and stable, which results in a drug product with a high proportion of CAR+ cells and high surface expression, potentially enhancing antigen binding and more efficient Multiple Myeloma cell killing. The data continue to demonstrate robust long-term responses with median duration of response, progression free survival (PFS), and overall survival rate not reached.

The data are from an October 15, 2023 data cut, with median follow-up after anito-cel infusion of 26.5 months. The company also has a medical affairs booth (#748) in Hall E of the San Diego Convention Center. As of October 15, 2023, 38 patients were evaluable for efficacy and safety analysis based on a median follow-up of 26.5 months following treatment.

Further, 24 of 38 (63%) had at least one high-risk clinical feature, defined as presence of EMD,BMPC >60%, or Beta 2 microglobulin (B2M) >5.5 mg/L at screening/baseline. All 38 patients had at least three prior lines of therapy. The interim anito-cel Phase 1 clinical results (October 15, 2023 cutoff date) demonstrate deep and durable responses in patients with poor prognostic factors.

All Patients: Of the 38 evaluable patients with a median follow-up of26.5 months:00% overerall response rate (ORR) achieved in all patients per IMWG criteria; 29 of 38 evaluable patatients achieved a complete response (CR) or a stringent complete response (sCR) (>CR rate, 76%); 35 of 38 patients achieved a very good partial response or higher (>VGPR rate, 92%) Of those evaluable for MRD testing to date (n=28), 25 (89%) were MRD-negive at a minimum of 10(-5) sensitivity.