Vaccination of cancer patients against telomerase induces functional antitumor CD8+ T lymphocytes.
(Clinical Trial;Journal Article)
PURPOSE: High-level expression of the telomerase reverse transcriptase (hTERT) in >85% of human cancers, in contrast with its restricted expression in normal adult tissues, points to hTERT as a broadly applicable molecular target for anticancer immunotherapy. CTLs recognize peptides derived from hTERT and kill hTERT+ tumor cells of multiple histologies in vitro. Moreover, because survival of hTERT+ tumor cells requires functionally active telomerase, hTERT mutation or loss as a means of escape may be incompatible with sustained tumor growth. EXPERIMENTAL DESIGN: A Phase I clinical trial was performed to evaluate the clinical and immunological impact of vaccinating advanced cancer patients with the HLA-A2-restricted hTERT I540 peptide presented with keyhole limpet hemocyanin by ex vivo generated autologous dendritic cells. RESULTS: As measured by peptide/MHC tetramer, enzyme-linked immunospot, and cytotoxicity assays, hTERT-specific T lymphocytes were induced in 4 of 7 patients with advanced breast or prostate carcinoma after vaccination with dendritic cells pulsed with hTERT peptide. Tetramer-guided high-speed sorting and polyclonal expansion achieved highly enriched populations of hTERT-specific cells that killed tumor cells in an MHC- restricted fashion. Despite concerns of telomerase activity in rare normal cells, no significant toxicity was observed. Partial tumor regression in 1 patient was associated with the induction of CD8+ tumor infiltrating lymphocytes. CONCLUSIONS: These results demonstrate the immunological feasibility of vaccinating patients against telomerase and provide rationale for targeting self-antigens with critical roles in oncogenesis.
Vonderheide, RH; Domchek, SM; Schultze, JL; George, DJ; Hoar, KM; Chen, D-Y; Stephans, KF; Masutomi, K; Loda, M; Xia, Z; Anderson, KS; Hahn, WC; Nadler, LM
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