Phase Ib study of TSPP (thymidilate synthase poly-epitope peptide) vaccine in combination with GOLFIG chemoimmuno-burst in advanced colon cancer patients: Results from the TSPP/VAC-1/c trial.

e13098 Background: TSPP is a poly-epitope peptide anticancer vaccine able to generate a thymidylate syntase (TS) specific T cell response with antitumor activity in preclinical models, expecially when used in sequential combination with 5-FU. TS is in fact involved in DNA replication and is the major pharmacological target of fluoropyrimidines whose activity leads in turn to TS upregulation. On these basis we designed a phase Ib trial where we investigated the safety and the immunobiological activity of TSPP + GOLFIG (Gemcitabine + FOLFOX-4 + GM-CSF + IL-2) regimen. Methods: TSPP/VAC-1 (Eudract 2009-016897-33) is a monocentric dose finding Phase Ib trial. 12 pretreated metastatic colon cancer patients were enrolled between April and November 2011. All of them received biochemotherapy according to the GOLFIG regimen biweekly and TSPP (on day 7) diluted in motanide ISA720 (1:1) at the dosage of 100 (3 patients), 200 (3 patients) and 300 ug (6 patients). Results: No life-threatening adverse events were observed. Grade 3 leucopenia (2 cases), thrombocitopenia (3 cases), anemia (3 cases), nausea/vomiting (2 cases), and dyarrhea (4 cases) along with 3 cases of oxaliplatin reaction were recorded. Fever and flu-like symptoms were common along cytokine administration. An IFN-gamma ELISPOT assay recorded an increase in TS specific CTL precursors in 3/6 evaluable patients; it was also observed an increase in lymphocytes, eosinophils, terminal effector memory and central memory T cells and in both c-ANCA and p-ANCA (P= 0.02) in the peripheral blood and a significant reduction in inflammatory markers (LDH, CRP and ESR). Quality of life analysis revealed a general improvement in patients’health state along the treatment. 1 partial response, 6 disease stabilizations and 2 progessions of disease were recorded. TSPP Maximal Tolerated Dose was not reached, while the Optimal Biological Dose was identified at 300 ug. Conclusions: Our results suggest that the GOLFIG + TSPP vaccine combination is safe and immunologically active and deserves to be evaluated in a further phase II trial.