Adoptive T Cell Therapy Using Antigen-Specific CD8⁺ T Cells for the Treatment of Patients with Cancer: A Phase I Clinical Study.

The adoptive transfer of in vitro induced and expanded tumor antigen-specific cytotoxic T lymphocytes (CTL) provides a promising approach to the immunotherpy of cancer. We have previously shown that antigen-specific CTL can be generated from HLA-A2.1⁺ cancer patients by 4 rounds of in vitro stimulation of purified CD8⁺ T cells with autologous dendritic cells pulsed with HLA-A2 binding tumor-associated peptides. Based on these results we have initiated a pilot study of adoptive T cell therapy in advanced melanoma patients demonstrating that in vitro generated Melan-A (ELAGIGILTV)-specific CTL survive intact in vivo for several weeks and localize preferentially to tumor. Here we report on the clinical results of a phase I study of 11 HLA-A2⁺ melanoma patients that received at least three i.v. infusions of Melan-A-specific CTL i.v. at 2-week intervals. Each T cell infusion was accompanied by a 6-day course of s.c. IL-2 (3x10⁶ IU daily). A total of 51 T-cell infusions were administered, averaging 2.1 x10⁸ Melan-A specific T cells per infusion, with a range from 0.11 – 13.1 x10⁸ T cells per infusion. Clinical side effects were mild and consisted of chills and low-grade fever (WHO grade I–II) in 7 out of 11 patients that typically occurred within 6 to 8 h post infusion. Hematological effects, observed after T cell transfer, included an increase in eosinophils up to 50% in 7 out of 11 patients, peaking 24h post transfer. Clinical and immunological responses consisted of antitumor responses in 3 out of 11 patients (1 CR, 1 PR, 1 mixed response), an elevated frequency of circulating Melan-A multimer⁺ T cells up to 2% of total CD8⁺ T cells for 2 weeks post T cell infusion, suggesting long-term survival and/or proliferation of transferred CTL, and a complete loss of Melan-A expression in lymph node metastases of 2 patients after T cell transfer. Our data indicate that the adoptive transfer of antigen-specific T cells in cancer patients is capable of inducing clinical and systemic tumor-specific immune responses without provoking major side effects.