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Standard fludarabine plus cyclophosphamide has been selected as the only lymphodepletion regimen that will be used in the phase 2 ALPHA3 trial (NCT06500273) investigating first-line consolidation therapy with cemacabtagene ansegedleucel (cema-cel; formerly ALLO-501/A) in patients with large B-cell lymphoma (LBCL).1
The lymphodepletion regimen was chosen via collaboration with the ALPHA3 Data and Safety Monitoring Board and Steering Committee, and this decision followed a consultation with the FDA.
Moreover, the arm of the trial evaluating cema-cel following lymphodepletion with fludarabine plus cyclophosphamide in combination with the CD52-directed monoclonal antibody ALLO-647 has been closed to further enrollment. This decision was made before the scheduled futility analysis due to the occurrence of a death in the cema-cel/fludarabine/cyclophosphamide/ALLO-647 arm that was attributed to treatment with ALLO-647. The grade 5 adverse effect of hepatic failure occurred on day 54 post-infusion and is believed to have been related to a disseminated adenovirus infection in the immune suppression setting. Notably, this event was deemed unrelated to treatment with cema-cel.
When severe viral infections have arisen in clinical trials initiated by Allogene Therapeutics—the developer of cema-cel—they have been partly attributed to immunosuppression from ALLO-647 use, according to a news release. However, Allogene trial investigators have reported no cases of hepatic failure or adenoviral infection in patients receiving lymphodepletion with fludarabine plus cyclophosphamide.
Now that standard fludarabine plus cyclophosphamide has been adopted as the lymphodepletion strategy for the ALPHA3 trial, no pipeline programs or trials that are open to enrollment are investigating ALLO-647.
“The loss of a patient is always deeply saddening, and we extend our heartfelt condolences to the patient’s family,” David Chang, MD, PhD, president, chief executive officer, and co-founder of Allogene, stated in the news release. “This event, which prompted an early review of the trial data, compelled us to make a decisive choice—one that may ultimately help bring this potentially life-saving therapy to patients more quickly. The ability to administer cema-cel following standard fludarabine plus cyclophosphamide lymphodepletion in an outpatient setting will simplify study treatment and has the potential to accelerate trial enrollment and streamline regulatory review, ultimately transforming care for patients.”
The amended ALPHA3 trial is a 2-arm randomized study of cema-cel following standard fludarabine plus cyclophosphamide lymphodepletion vs observation—the current standard of care for patients with LBCL following first-line treatment. Notably, the statistical design and prespecified conduct of the trial remain the same after the removal of the ALLO-647–containing arm.
The ongoing trial is enrolling patients at least 18 years of age with LBCL per WHO 2017 criteria—including diffuse LBCL, high-grade B-cell lymphoma, and primary mediastinal B-cell lymphoma—that is confirmed by a pathology report.2 Patients need to have completed a full course of standard first-line therapy, such as R-CHOP (rituximab [Rituxan], cyclophosphamide, doxorubicin, vincristine, and prednisone), dose-adjusted EPOCH-R (etoposide phosphate, prednisone, vincristine sulfate [Oncovin], cyclophosphamide, doxorubicin hydrochloride [Hydroxydaunorubicin], and rituximab) or Pola-R-CHP (polatuzumab vedotin-piiq [Polivy], rituximab, cyclophosphamide, doxorubicin, and prednisone); patients must not have received additional lines of therapy. Following first-line therapy, patients must have achieved a complete or partial response suitable for observation at the end of first-line therapy. Patients must also have an ECOG performance status of 0 or 1, as well as adequate renal, hematological, pulmonary, hepatic, and cardiac function. Nonhematologic toxicities associated with prior therapy must be recovered to baseline levels or grade 1 or lower.
Event-free survival serves as the trial’s primary end point. Secondary end points include progression-free survival, overall survival, safety, and minimal residual disease (MRD) clearance.
The futility analysis comparing MRD conversion rates between the 2 ongoing ALPHA3 arms is expected to occur in the first half of 2026.1
References
- Allogene Therapeutics moves forward with standard fludarabine and cyclophosphamide (FC) lymphodepletion regimen in the ALPHA3 trial for cemacabtagene ansegedleucel (cema-cel) in first-line consolidation for large B-cell lymphoma. News release. Allogene Therapeutics, Inc. August 1, 2025. Accessed August 4, 2025. https://ir.allogene.com/news-releases/news-release-details/allogene-therapeutics-moves-forward-standard-fludarabine-and
- Consolidation of first-line MRD+ remission with cema-cel in patients with LBCL (ALPHA3). ClinicalTrials.gov. Updated June 25, 2025. Accessed August 4, 2025. https://clinicaltrials.gov/study/NCT06500273