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RESEARCH PRODUCT

Association of immune-regulatory (FoxP3+)-T-cell tumor infiltration status with benefit from chemoimmunotherapy with gemcitabine, oxaliplatin, 5-FU/FA plus GM-CSF and aldesleukine (GOLFIG) in metastatic colon cancer patients

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3045 Background: GOLFIG is a novel chemoimmunotherapy regimen, combining gemcitabine, oxaliplatin, 5-FU/FA with immunoadjuvant GM-CSF and aldesleukine, which resulted safe and very active in colon cancer patients. Antitumor activity and immunity feedback to the treatment resulted strictly correlated. The best outcome was observed in patients showing autoimmunity signs, rise in central-memory-T cells, and decline in peripheral and tumor infiltrating immuno-regulatory T (Treg) cells. On these bases, we investigated a possible correlation between Treg tumor infiltration at diagnosis and clinical outcome of these patients. Methods: An immunohistochemistry study was carried out to quantify the infiltration of Treg (FoxP3+) lymphocytes in tumor samples of 41 colon cancer patients who received FOLFOX-4 chemotherapy or GOLFIG chemo-immunotherapy as enrolled in the ongoing phase III GOLFIG-2 trial. Treg tumor infiltration score (range 0 to 5) was then correlated with survival (OS) and time to progression (TTP). Results: A higher Treg tumor infiltration score (score 3–5) was associated to a longer OS and TTP in the whole patient population (high vs low score; TTP=18 vs 9.4 months; p=0.002; OS=55.7 vs 28.9 months; p=0.001); however, those patients with high tumor infiltration of FoxP3+-T cells who received GOLFIG regimen showed the most favorable outcome (high vs low score; TTP=20.8 vs 11.6 months; p=0.04; OS=68.1 vs 41 months; p=0.04). A Cox regression model demonstrated in these patients that a high Treg tumor infiltration score is an independent variable of long survival and prolonged TTP. Conclusions: Our results suggest that GOLFIG chemoimmunotherapy is highly effective in colon carcinoma patients with high FoxP3+ infiltration score and that Treg-tumor infiltration score may be a favorable prognostic marker in colon cancer patients. No significant financial relationships to disclose.