Arcellx Inc. (ACLX) is having a very good Monday after dropping some seriously impressive clinical trial results over the weekend. The biotech company shared updated data from its pivotal Phase 2 iMMagine-1 study of anitocabtagene autoleucel (anito-cel for short) in patients with relapsed or refractory multiple myeloma.
The presentation happened Saturday at the 2025 American Society of Hematology Annual Meeting, and the numbers are the kind that make investors sit up and pay attention. Anito-cel is being developed in partnership with Kite Pharma, which is owned by Gilead Sciences Inc. (GILD).
What The Data Shows
Here's what matters: The updated results cover all 117 patients in the study, with a median follow-up of 15.9 months. The data cutoff was October 7, 2025, which also happens to be the cutoff for the company's upcoming biologics license application submission.
Each patient received a single infusion of anito-cel at a target dose of 115×10⁶ CAR+ viable T cells. The results continue to show deep and durable responses with what the company describes as a predictable and manageable safety profile in this heavily pretreated patient population (fourth-line or higher treatment).
The overall response rate hit 96% (112 out of 117 patients), with 74% achieving complete response or stringent complete response and 88% reaching very good partial response or better. Those are remarkable numbers for patients who've already been through multiple treatment regimens.
On the minimal residual disease front, 95% of evaluable patients (91 out of 96) achieved MRD negativity. Even more impressive, 83% of those with sufficient follow-up sustained that negativity for more than six months at a sensitivity of at least 10⁻⁵.
Survival Rates Tell The Story
The survival data shows durability over time. Six-month progression-free survival and overall survival rates came in at 93.1% and 95.7%, respectively. At 12 months, those rates were 82.1% and 94.0%. By 18 months: 67.4% and 88.0%. And at the two-year mark, 61.7% progression-free survival and 83% overall survival.
Notably, median progression-free survival and median overall survival haven't been reached yet, which means more than half the patients are still benefiting from treatment.
On the safety side, Arcellx emphasized that no delayed or non-ICANS neurotoxicities have been observed with anito-cel in patients dosed more than 12 months ago. That includes no Parkinsonism, no cranial nerve palsies, no Guillain-Barré syndrome, and no immune effector cell-associated enterocolitis—all complications that have shown up with other CAR-T therapies.
The company reiterated its expected commercial launch timeline of 2026.
What Analysts Are Saying
William Blair came away impressed, writing that the data "reinforce anito-cel's best-in-class profile, with deeper responses and durable benefit emerging over time." Analyst Sami Corwin went further, suggesting that "anito-cel's efficacy/safety profile could drive earlier-line adoption and outpatient use."
That last bit about outpatient use is significant. CAR-T therapies have traditionally required extensive hospitalization and monitoring, so a treatment that could be given in an outpatient setting would be a meaningful advance.
Needham maintained its Buy rating on Arcellx with a $105 price target.
ACLX Price Action: Arcellx shares were up 10.12% at $76.59 at the time of publication on Monday.