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Supplementary Table 1 from Dacarbazine Treatment before Peptide Vaccination Enlarges T-Cell Repertoire Diversity of Melan-A–Specific, Tumor-Reactive CTL in Melanoma Patients

Supplementary Figure Legend from Dacarbazine Treatment before Peptide Vaccination Enlarges T-Cell Repertoire Diversity of Melan-A–Specific, Tumor-Reactive CTL in Melanoma Patients

Combination of chemotherapy and immunotherapy to increase the effectiveness of an antitumor immune response is currently regarded as an attractive antitumor strategy. In a pilot clinical trial, we have recently documented an increase of melanoma antigen A (Melan-A)–specific, tumor-reactive, long-lasting effector-memory CD8+ T cells after the administration of dacarbazine (DTIC) 1 day before peptide vaccination in melanoma patients. Global transcriptional analysis revealed a DTIC-induced activation of genes involved in the immune response and leukocyte activation. To identify the possible mechanisms underlying this improved immune response, we have compared the endogenous and the treatment-induced anti–Melan-A response at the clonal level in patients treated with the vaccine alone or with DTIC plus vaccine. We report a progressive widening of T-cell receptor (TCR) repertoire diversity, accompanied by high avidity and tumor reactivity, only in Melan-A–specific T-cell clones of patients treated with chemoimmunotherapy, with a trend toward longer survival. Differently, patients treated with vaccine alone showed a tendency to narrowing the TCR repertoire diversity, accompanied by a decrease of tumor lytic activity in one patient. Collectively, our findings indicate that DTIC plus vaccination shapes the TCR repertoire in terms of diversity and antitumor response, suggesting that this combined therapy could be effective in preventing melanoma relapse. Cancer Res; 70(18); 7084–92. ©2010 AACR.

Supplementary Methods from Dacarbazine Treatment before Peptide Vaccination Enlarges T-Cell Repertoire Diversity of Melan-A–Specific, Tumor-Reactive CTL in Melanoma Patients

Supplementary Figure 1 from Dacarbazine Treatment before Peptide Vaccination Enlarges T-Cell Repertoire Diversity of Melan-A–Specific, Tumor-Reactive CTL in Melanoma Patients

Combination of chemotherapy and immunotherapy to increase the effectiveness of an antitumor immune response is currently regarded as an attractive antitumor strategy. In a pilot clinical trial, we have recently documented an increase of melanoma antigen A (Melan-A)–specific, tumor-reactive, long-lasting effector-memory CD8+ T cells after the administration of dacarbazine (DTIC) 1 day before peptide vaccination in melanoma patients. Global transcriptional analysis revealed a DTIC-induced activation of genes involved in the immune response and leukocyte activation. To identify the possible mechanisms underlying this improved immune response, we have compared the endogenous and the treatment-induced anti–Melan-A response at the clonal level in patients treated with the vaccine alone or with DTIC plus vaccine. We report a progressive widening of T-cell receptor (TCR) repertoire diversity, accompanied by high avidity and tumor reactivity, only in Melan-A–specific T-cell clones of patients treated with chemoimmunotherapy, with a trend toward longer survival. Differently, patients treated with vaccine alone showed a tendency to narrowing the TCR repertoire diversity, accompanied by a decrease of tumor lytic activity in one patient. Collectively, our findings indicate that DTIC plus vaccination shapes the TCR repertoire in terms of diversity and antitumor response, suggesting that this combined therapy could be effective in preventing melanoma relapse. Cancer Res; 70(18); 7084–92. ©2010 AACR.

A phase II randomized clinical study is ongoing in our Institution to prove the clinical efficacy of dacarbazine (DTIC) one day before peptide-vaccination (Melan-A and NY-ESO-1) in the prevention of melanoma relapse in clinically disease-free HLA-A2 patients. In a previous pilot study, this combination therapy (using Melan-A and gp100 peptides) increased the number of tumor-reactive long-lasting effector-memory CD8+ lymphocytes. To identify the mechanisms enhancing the immune response, induced by DTIC combined with peptide-vaccination, we analyzed the endogenous and treatment-induced antigen specific CD8 T-cell response at the clonal level. We analyzed the sequence of the TCR α-chain of these clones and the molecular results were correlated with the expression of CD27/CD28 co-stimulatory molecule, AKT activation and anti-tumor lytic activity. The combination of chemo/immunotherapy elicited in Melan-A-specific, but not in gp100 clones, a renewal of high-avidity/tumor-reactive T-cell clones, with a broadening TCR diversity in long-surviving patients, suggesting that the selection of immune-resistant tumor variants may be circumvented by this combination, and thus prevent tumor recurrence in melanoma. In gp100 clones, AKT activation (pSer473-AKT) canonically correlates with CD28 and/or CD27 expression, independent of the treatment while in Melan-A clones, lacking CD27 and CD28 expression, non-canonical AKT activation was only observed after the combination therapy. The identification of the extracellular stimuli and signaling pathway responsible for DTIC-mediated activation of the AKT signaling are currently under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4406. doi:1538-7445.AM2012-4406