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Supplementary Data from Gut Microbiota Condition the Therapeutic Efficacy of Trastuzumab in HER2-Positive Breast Cancer

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posted on 2023-03-31, 04:43 authored by Martina Di Modica, Giorgio Gargari, Viola Regondi, Arianna Bonizzi, Stefania Arioli, Beatrice Belmonte, Loris De Cecco, Elena Fasano, Francesca Bianchi, Alessia Bertolotti, Claudio Tripodo, Laura Villani, Fabio Corsi, Simone Guglielmetti, Andrea Balsari, Tiziana Triulzi, Elda Tagliabue
<p>1. Supplementary Materials and Methods Table S1. List of the antibodies used for flow cytometry 2. Supplementary Figures Supplementary Fig. S1. Impact of antibiotic treatment on trastuzumab efficacy and the tumor microenvironment. Supplementary Fig. S2. Depletion of commensal microbiota by antibiotic cocktail (ABX) treatment and fecal microbiota transplantation. Supplementary Fig. S3. Impact of vancomycin on trastuzumab efficacy in Î"16HER2 transgenic FVB mice. Supplementary Fig. S4. Differentially abundant bacteria in the gut microbiota of antibiotic-treated mice. Supplementary Fig. S5. Short-chain fatty acids (SCFAs) quantification in fecal samples from antibiotic-treated mice. Supplementary Fig. S6. Analysis of intratumor and stromal cell staining in tumors of antibiotic-treated mice. Supplementary Fig. S7. Impact of antibiotic treatment on tumor immune infiltrate. Supplementary Fig. S8. Analysis of intratumor and stromal cell staining in tumors from FMT mice. Supplementary Fig. S9. Impact of vancomycin treatment on intestinal and systemic immune features. Supplementary Fig. S10. Impact of IL12p70 and CD4+ cell depletion on trastuzumab antitumor efficacy and on tumor immune infiltrate. Supplementary Fig. S11. Causal role of human commensal bacteria in immune-mediated trastuzumab antitumor efficacy. 3. Supplementary References</p>

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ARTICLE ABSTRACT

Emerging evidence indicates that gut microbiota affect the response to anticancer therapies by modulating the host immune system. In this study, we investigated the impact of gut microbiota on immune-mediated trastuzumab antitumor efficacy in preclinical models of HER2-positive breast cancer and in 24 patients with primary HER2-positive breast cancer undergoing trastuzumab-containing neoadjuvant treatment. In mice, the antitumor activity of trastuzumab was impaired by antibiotic administration or fecal microbiota transplantation from antibiotic-treated donors. Modulation of the intestinal microbiota was reflected in tumors by impaired recruitment of CD4+ T cells and granzyme B–positive cells after trastuzumab treatment. Antibiotics caused reductions in dendritic cell (DC) activation and the release of IL12p70 upon trastuzumab treatment, a mechanism that was necessary for trastuzumab effectiveness in our model. In patients, lower α-diversity and lower abundance of Lachnospiraceae, Turicibacteraceae, Bifidobacteriaceae, and Prevotellaceae characterized nonresponsive patients (NR) compared with those who achieved pathologic complete response (R), similar to antibiotic-treated mice. The transfer of fecal microbiota from R and NR into mice bearing HER2-positive breast cancer recapitulated the response to trastuzumab observed in patients. Fecal microbiota β-diversity segregated patients according to response and positively correlated with immune signature related to interferon (IFN) and NO2-IL12 as well as activated CD4+ T cells and activated DCs in tumors. Overall, our data reveal the direct involvement of the gut microbiota in trastuzumab efficacy, suggesting that manipulation of the gut microbiota is an optimal future strategy to achieve a therapeutic effect or to exploit its potential as a biomarker for treatment response. Evidence of gut microbiota involvement in trastuzumab efficacy represents the foundation for new therapeutic strategies aimed at manipulating commensal bacteria to improve response in trastuzumab-resistant patients.See related commentary by Sharma, p. 1937

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