Shares of Allogene Therapeutics (NASDAQ:ALLO) surged 36% on Monday after the company disclosed positive interim findings from the ALPHA3 pivotal trial. The readout focused on cemacabtagene ansegedleucel - referred to as cema-cel - in patients receiving first-line consolidation for large B-cell lymphoma.
The interim futility assessment reported a 58.3% rate of minimal residual disease (MRD) clearance in the cema-cel arm versus 16.7% in the observation arm, yielding an absolute difference of 41.6 percentage points. That gap exceeds the clinically meaningful threshold cited in the literature, which ranges from 25% to 30%.
At the first MRD measurement on Day 45, plasma circulating tumor DNA (ctDNA) levels fell by a median of 97.7% in patients treated with cema-cel. By contrast, the observation arm saw a median ctDNA increase of 26.6% at the same time point. These efficacy and biomarker results derive from 24 patients who were randomized evenly between the two trial arms.
Safety and tolerability signals in this interim analysis were notable: investigators reported no cases of cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome (ICANS), graft-versus-host disease, or treatment-related serious adverse events. Additionally, 10 of the 12 patients who received cema-cel were managed exclusively in the outpatient setting following infusion.
Operational details in the update highlighted community cancer centers' role in the study. Approximately one-third - about 33% - of screening activity and cema-cel infusions took place at community sites, including locations with little to no prior CAR T therapy experience.
The ALPHA3 study is active at more than 60 sites and aims to enroll roughly 220 patients. Trial organizers expect enrollment to conclude by year-end 2027. Key timing milestones include an interim event-free survival (EFS) analysis slated for mid-2027 and the primary EFS analysis anticipated in mid-2028.
The study's primary endpoint is event-free survival. Important secondary endpoints include progression-free survival and overall survival. The trial is powered to detect a 50% reduction in the risk of EFS events, which are defined to include initiation of new anti-lymphoma therapy, disease progression, or death.
Contextual note - The data reported here stem from an interim futility analysis with a limited patient set (24 randomized patients). While the magnitude of the MRD and ctDNA differences is substantial in this cohort, broader conclusions will depend on outcomes from the full enrollment and the planned event-driven analyses.