Expansion of Cytomegalovirus pp65 and IE-1 Specific Cytotoxic T Lymphocytes for Cytomegalovirus-Specific Immunotherapy Following Allogeneic Stem Cell Transplantation

Adoptive immunotherapy with antigen-specific cytotoxic T lymphocytes (CTLs) has proven effective in restoring cellular immunity to cytomegalovirus (CMV) and preventing viral reactivation after allogeneic stem cell transplantation (SCT). In an effort to develop a cost-effective, relatively rapid method of CMV CTL expansion, we investigated the use of a pool of overlapping CMV peptides. Because the possibility exists of vaccinating CMV-seronegative donors, and these individuals may have T cell responses predominantly against IE-1, commercially available peptide mixes for pp65 as well as IE-1 were used to stimulate CTLs from 10 seropositive donors. Of these 10 donors, 4 responded to pp65 only, 1 did not respond to either pp65 or IE-1, 4 responded to both pp65 and IE-1, and 1 responded to IE-1 only. These CMV- specific T cells included a mixture of CD4+ and CD8+ effectors, and specific cytotoxicity correlated with interferon-γ production. The costs associated with a 28-day maintenance course of intravenous ganciclovir, cidofovir, foscarnet, and valganciclovir, as well as the preparation and shipping a single dose of CTLs, were determined. The price of generating CMV CTLs using this method was comparable to or less expensive than a 28-day maintenance course for these agents, not including the costs associated with drug administration, supportive care, and the treatment of drug-related complications. Considering the relative ease, low cost, and the fact that CTL administration can result in CMV-specific immune reconstitution, this option should be considered for patients with CMV reactivation or for prophylaxis in patients at high risk for infection.