Exhibit 99.1
Arcellx Announces Continued Robust Long-Term Responses from Its
CART-ddBCMA (anito-cel) Phase 1 Expansion Trial in Patients with Relapsed or
Refractory Multiple Myeloma at ASH
Median duration of response, progression free survival, and overall survival rate not reached with
median follow-up after CART-ddBCMA (anito-cel) infusion of 26.5
months
The estimated median progression free survival by Kaplan-Meier is 28 months
Oral presentation at ASH will be on Monday, December 11, 2023 at 5 p.m. PT
Company to host a live webcast event with an expert panel of clinicians on Monday, December 11 at 8 p.m.
REDWOOD CITY, Calif., December 8, 2023 /PRNewswire/ Arcellx, Inc. (NASDAQ: ACLX), a biotechnology company
reimagining cell therapy through the development of innovative immunotherapies for patients with cancer and other incurable diseases, today 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. These latest study findings will be
presented as an oral presentation during the 65th American Society of Hematology (ASH) Annual Meeting and Exposition on Monday, December 11, 2023 at 5 p.m. PT. 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. These evaluable patients comprised the dose escalation cohorts for the first dose level (100 (+/- 20) million CAR+ T cells, n=6) and the second dose level (300 (+/- 20)
million CAR+ T cells, n=6), and a dose expansion cohort at 100 (+/- 20) million CAR+ T cells (n=26). The median dose administered to patients in the first dose level and dose expansion cohorts was 115 million CAR+ T cells. All patients
evaluable for this analysis have poor prognostic factors with 38 of 38 (100%) patients triple-refractory, 26 of 38 (68%) penta-refractory, and 34 of 38 (89%) refractory to last line of treatment under International Myeloma Working Group (IMWG)
criteria. Additionally, 9 of 38 (24%) patients had high tumor burden with >60% bone marrow plasma (BMPC) cells, 13 of 38 (34%) patients had extra-medullary disease (EMD), and 11 of 38 (29%) patients had high-risk cytogenetics (Del 17p,
t(14;16), t(4;14)) at screening/baseline. 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.