Investigational T-Cell Therapy Safe, Effective Against Common Viruses in Allo-HCT Recipients

January 24, 2023

Posoleucel, an investigational, allogeneic, off-the-shelf, multi-virus specific T-cell therapy, appears to be safe and effective against six viral infections that commonly occur in patients who have received an allogeneic hematopoietic cell transplant (allo-HCT), according to research published this month in Clinical Cancer Research.  

In an open-label, phase II clinical trial, investigators studied the feasibility and safety of posoleucel (AlloVir, Inc.) in 58 adult and pediatric allo-HCT recipients with one or more of the following infections: adenovirus, BK virus, cytomegalovirus, Epstein–Barr virus, human herpes virus-6 or JC virus. Infections were either unresponsive or patients were unable to tolerate standard antiviral therapies.

Posoleucel was well tolerated, with no cytokine release syndrome or other infusion-related toxicities; however, two patients (3.4%) developed Grade 2 and one patient (1.7%) Grade 3 graft-versus-host disease (GVHD) during the trial.

Posoleucel was also effective, with 55 of all 58 patients (95%; 95% CI) experiencing a partial response (defined as a viral load reduction of greater than or equal to 50%) or complete response (defined as return of viral load to normal range) six weeks after posoleucel infusion. Of the 12 patients with more than one target virus identified at study entry, 10 (83%) reported either a partial or complete response for all evaluable target viruses by six weeks post-infusion.

According to investigators, viral infections remain a major cause of morbidity and mortality following allo-HCT, with up to 90% of patients experiencing reactivation of at least one virus and almost two thirds of patients developing infections with more than one virus. Posoleucel, the authors believe, “might aid in alleviating the morbidity and mortality associated with post-HCT viral infections and help avoid the nephrotoxic and myelosuppressive side effects associated with the use of conventional antiviral medications.”

Based on these findings, posoleucel is currently being evaluated in three randomized phase III trials for both treatment and preventive indications.