Arcellx (ACLX) Status Update summary

Evolving multiple myeloma landscape and therapy differentiation

• Anito-cel demonstrates high efficacy and safety, with durable responses and minimal neurotoxicity, distinguishing it from both bispecifics and other CAR T therapies.

• Real-world data show anito-cel's safety profile enables broader adoption, with low rates of CRS, ICANS, and delayed neurotoxicities.

• Bispecifics face challenges with higher infection rates and limited real-world efficacy, while CAR T therapies like anito-cel maintain robust outcomes.

• Combination studies with Dara can inflate efficacy, but real-world patient populations are increasingly Dara-refractory, making such results less generalizable.

• Anito-cel is positioned as a category-defining therapy, with potential for mass adoption due to its unique combination of efficacy, safety, and scalability.

Clinical efficacy and safety profile

• Anito-cel achieved a 96% overall response rate and 74% complete/strict complete response at 15.9 months median follow-up in relapsed/refractory multiple myeloma patients.

• Minimal residual disease negativity was 95%, with 83% sustaining negativity for at least 6 months at high sensitivity.

• Progression-free survival and overall survival rates at 24 months were 62% and 83%, respectively; median PFS and OS not reached.

• Safety profile is favorable: 83% had ≤Grade 1 CRS (15% no CRS), 92% had no ICANS, and zero cases of delayed or non-ICANS neurotoxicity observed.

• Efficacy and safety consistent across high-risk subgroups, with no new treatment-related deaths or secondary malignancies reported.

Study and patient characteristics

• Data cutoff was October 7, 2025, covering 117 patients with a median of three prior therapy lines; 87% were triple refractory, 41% penta refractory, and 40% had high-risk cytogenetics.

• All patients received a single infusion of anito-cel at a target dose of 115 × 10^6 CAR+ viable T cells.

• The study population included patients with extramedullary disease and high-risk features.

• Responses continue to deepen over time, with a predictable and manageable safety profile in a heavily pretreated population.

• Effective bridging therapy and disease control prior to CAR T infusion are critical for optimal outcomes and reduced toxicity.