A Randomized prospective study to assess the immunomodulatory effect of a probiotic supplement in patients with solid tumors under immunotherapy

Introduction: Recent studies have correlated the administration of probiotics with better response to immunotherapy in patients with solid tumors.To our Knowledge, this is the first randomized clinical prospective study conducted in patients with solid tumors receiving immunotherapy with or without chemotherapy, aiming to investigate the possible immunomodulatory role of a commercial probiotic formulation Aim: We investigated whether the addition of a probiotic formula versus placebo will augment the efficacy of immunotherapy in patients with solid tumors Methods: This is a randomized double blind prospective study. Since the start of the trial (December 2021), 15 patients have completed the study: 8 were given the probiotic formula and 7 placebo. Peripheral blood was collected from patients before and after three treatment cycles (every 42 days) and total lymphocytes, CD3+CD4+, and CD3+CD8+ T lymphocytes, B cells (CD19+), natural killer cells (CD16-CD56+), PDL-1+ cells, and the more specialized regulatory T cells (CD4+CD25+CD127-), were detected by flow cytometry.PDL1, TIGIT,IL-6 and Il-8 levels were measured with ELISA. During the study, the clinical course of the patients, response to treatment along with serial evaluations of quality of life monitoring were documented. The trial is still ongoing recruiting patients Results: Our first interim analysis showed that there is a statistical significant correlation of PDL-1 levels with the probiotic arm. In particular, in the arm of patients receiving the probiotic formula, a statistical significant decrease in PDL-1 levels was observed. Regarding IL-6, and TIGIT levels, our first interim analysis indicates a statistical significant trend towards greater reduction of TIGIT and IL-6 levels in patients receiving the probiotic formula Conclusions: Our first interim analysis indicates a positive effect of probiotics in our study population. Larger number of patients are needed to confirm our preliminary results.