Immunization with mutant p53- and K-ras-derived peptides in cancer patients: immune response and clinical outcome.

PURPOSE: To determine the ability to induce tumor-specific immunity with individual mutant K-ras-or p53-derived peptides and to monitor clinical outcome. PATIENTS AND METHODS: Patients in varying stages of disease underwent genetic analysis for mutations in K-ras and p53. Thirty-nine patients were enrolled. Seventeen-mer peptides were custom synthesized to the corresponding mutation. Baseline immunity was assessed for cytotoxic T-lymphocyte (CTL) response and interferon gamma (IFN-gamma) release from mutant peptide-primed lymphocytes. Patients' peripheral-blood mononuclear cells were pulsed with the corresponding peptide, irradiated, and applied intravenously. Patients were observed for CTL, IFN-gamma, interleukin (IL) -2, IL-5, and granulocyte-macrophage colony-stimulating factor responses, for treatment-related toxicity, and for tumor response. RESULTS: No toxicity was observed. Ten (26%) of 38 patients had detectable CTL against mutant p53 or K-ras, and two patients were positive for CTL at baseline. Positive IFN-gamma responses occurred in 16 patients (42%) after vaccination, whereas four patients had positive IFN-gamma reaction before vaccination. Of 29 patients with evident disease, five experienced a period of stable disease. Favorable prognostic markers were detectable CTL activity and a positive IFN-gamma reaction but not IL-5 release. Median survival times of 393 v 98 days for a positive versus negative CTL response (P = .04), respectively, and of 470 v 88 days for a positive versus negative IFN-gamma response (P = .02), respectively, were detected. CONCLUSION: Custom-made peptide vaccination is feasible without any toxicity. CTL and cytokine responses specific to a given mutation can be induced or enhanced with peptide vaccines. Cellular immunity to mutant p53 and K-ras oncopeptides is associated with longer survival.

Radioimmunotherapy of interleukin-2R - expressing adult T-cell leukemia with yttrium-90-labeled anti-tac

Adult T-cell leukemia (ATL) is a malignancy of mature lumphocytes caused by the retrovirus human T-cell lymphotropic virus-I. It is an aggressive leukemia with a median survival time of 9 months: no chemotherapy regimen appears successful inducing long-term disease-free survival. The scientific basis of the present study is the ATL cells express high-affinity interleukin-2 receptors identified by the anti-Tac monoclonal antibody, whereas normal resting cells do not. To exploit this differnce, we administered anti-Tac armed with Yttrium-90 (Y) to 18 patients with ATL initially (first 9 patients) in a phase I dose-escalation trial and subsequently (second group of 9 patients) in a phase II trial involving a uniform 10-mCi dose of Y-labeled anti-Tac. Patients undergoing a remission were permitted to receive up to eight additional doses. At the 5-to 15-mCi doses used, 9 of 16 evaluable patients responded to Y anti-Tac with a partial (7 patients) or complete (2 patients) remission. The responses observed represent improved efficacy in terms of length of remission when compared with previous results with unmodified anti-Tac. Clinically meaningful (> grade 3) toxicity was largely limited to the hematopoietic system. In conclusion, radioimmunotherapy with Y anti-Tac directed toward the IL-2R expressed on ATL cells may provide a useful approach for treatment of this aggressive malignancy.(AU)