Comparable anti-CMV responses of transplant donor and third-party CMV-specific T cells for treatment of CMV infection after allogeneic stem cell transplantation

Adoptive transfer of cytomegalovirus(CMV)-specific cytotoxic T lymphocytes(CMV-CTLs)from original transplant donors or third-party donors was effective for the treatment of CMV infection after allogenic stem cell transplantation(allo-SCT),but the antiviral activity of CMV-CTL types has not been compared.To determine whether third-party CMV-CTLs provide comparable long-term antiviral efficacy to transplant donor CMV-CTLs,we first compared the antiviral abilities of transplant donors and third-party CMV-CTLs for treatment of CMV infection in two mouse models,compared the in vivo recovery of CMV-specific immunity,and analyzed the underlying mechanisms driving sustained antiviral immunity.The results showed that both donor and third-party CMV-CTLs effectively combated systemic CMV infection by reducing CMV pathology and tumor burden 28 days postinfusion.The in vivo recovery of CMV-specific immunity after CMV-CTL infusion was comparable in both groups.A detailed analysis of the source of recovered CMV-CTLs showed the proliferation and expansion of graft-derived endogenous CMV-CTLs in both groups.Our clinical study,which enrolled 31 patients who received third-party CMV-CTLs and 62 matched pairs of individuals who received transplant donor CMV-CTLs for refractory CMV infection,further showed that adoptive therapy with donor or third-party CMV-CTLs had comparable clinical responses without significant therapy-related toxicity.We observed strong expansion of CD8+tetramer+T cells and proliferation of recipient endogenous CMV-CTLs after CMV-CTL infusion,which were associated with a reduced or cleared viral load.Our data confirmed that adoptive therapy with third-party or transplant donor CMV-CTLs triggered comparable antiviral responses to CMV infection that might be mediated by restoration of endogenous CMV-specific immunity.