Outcomes and Challenges of Manufacturing Virus-Specific Cytotoxic T-lymphocytes Using IFN-gamma Cytokine Capture System

Abstract

Background & Aim Background Viral infection/reactivation after allogeneic hematopoietic stem cell (HSCT) or solid organ transplant (SOT) is a significant cause of morbidity and mortality in drug-refractory patients. Adoptive transfer of allogeneic virus-specific cytotoxic T lymphocytes (vCTLs) can rapidly restore antiviral T cell immunity. The IFN-gamma Cytokine Capture System (CCS, Miltenyi) provides a fast and automated method of isolating vCTLs by stimulating them with virus-specific peptides. Aim To evaluate the safety and efficacy of vCTLs manufactured using IFN-gamma CCS on CliniMACS Prodigy® in children and young adults (CAYA) and highlight technical aspects of vCTL manufacturing by this method. Methods, Results & Conclusion Methods CAYA HSCT or SOT recipients with refractory viral infections (CMV, ADV, EBV, BK) received adoptive transfer of vCTLs from haploidentical relatives or matched donors who screened positive for the relevant vCTL. Following non-mobilized leukocytapheresis, virus-specific CD4+ and CD8+ T cells were isolated using IFN-gamma CCS on CliniMACS Prodigy®. Results Fourteen patients have been treated to date (Table 1). Of patients treated for CMV, EBV, ADV, or their combination, 100% (9) achieved complete remission (CR). 2 out of 4 patients treated for BK achieved CR, 2 had partial remission (PR), and one patient treated for CMV/BK had resolution of CMV and no response (NR) to BK. There were no episodes of acute Grade II-IV GVHD, chronic GVHD, CRS, or infusion reactions. We noted occasional discordance between donor viral serology and their response to the stimulation by the viral Peptivator; for example, we successfully manufactured anti-ADV vCTLs from a donor who was serologically negative to adenovirus. Flow cytometry analysis of rare events in a limited sample required sequential gating strategy to maximally reduce background noise. Products thus manufactured have unique properties, such as low cell dose and high debris content, which may face additional regulatory scrutiny. Conclusion Despite its unique challenges, vCTL manufacturing is rapid, reproducible and effective, and vCTLs are safe and well tolerated in CAYA with HSCT and SOT.