Feasibility and Interim Safety and Efficacy Analysis of a Fast Automated Production of Prophylactic Cytomegalovirus-Specific Cytotoxic T Lymphocytes After Allogeneic Hematopoietic Stem Cell Transplantation.

Cytomegalovirus (CMV) infection remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT). Although letermovir prophylaxis has reduced CMV reactivation in seropositive patients, especially in high-risk settings, some patients remain ineligible in certain countries and continue to face significant risk. Adoptive transfer of donor-derived CMV-specific cytotoxic T lymphocytes (CTLs) may provide an immunologic strategy to prevent CMV reactivation and accelerate immune reconstitution. To evaluate the feasibility, safety, and preliminary efficacy of prophylactic infusion of donor-derived CMV-specific CTLs manufactured overnight using the automated CliniMACS Prodigy system after allogeneic hematopoietic stem cell transplantation (HSCT). This ongoing phase II multicenter study included adult recipients of HLA-identical related HSCT who were not eligible for letermovir prophylaxis. Patients received a single infusion of fresh donor-derived CMV-specific CTLs on day +21 (±7) post-transplant. CTLs were produced under GMP conditions using an automated IFNγ-based selection strategy following CMV pp65 peptide stimulation. The primary endpoint was the incidence of CMV reactivation by day +100 post-transplant compared with historical controls from our institution. Secondary endpoints included CMV disease, antiviral therapy requirement, and safety. Exploratory analyses evaluated in vivo CTL persistence by IFNγ flow cytometry at 30, 60, and 90 d postHSCT. Fourteen patients received CTL infusion and completed one-year follow-up. CMV reactivation by day +100 post-transplant occurred in 5 of 14 patients (36%), compared with 53% in the historical cohort. Median viral load at reactivation was 3600 IU/mL (range, 240 to 15,000), and all cases resolved without development of CMV disease. Three patients experienced mild infusion-related reactions that resolved without corticosteroid treatment. Acute GVHD incidence was similar to the historical cohort (36% versus 32%), whereas chronic GVHD incidence seemed to be higher (64% versus 47%). Two deaths occurred during follow-up due to relapse and chronic GVHD, both considered unrelated to CTL infusion. This interim analysis demonstrates the feasibility and acceptable safety profile of prophylactic infusion of donor-derived CMV-specific CTLs manufactured through a rapid automated process after allogeneic HSCT. Early results suggest a possible reduction in CMV reactivation without evidence of increased acute GVHD, although interpretation is limited by the small sample size. Ongoing recruitment and final study analysis will further define the clinical impact of this strategy.