Gut microbiome components predict response to neoadjuvant short-course radiotherapy followed by camrelizumab and chemotherapy in locally advanced rectal cancer (UNION): a prospective study
Qou, Qiai et al.
Background Although the gut microbiome shapes responses to anti-tumor immunotherapy and chemotherapy, its predictive value for neoadjuvant short-course radiotherapy (SCRT) followed by camrelizumab (CAM) and CAPOX in patients with locally advanced rectal cancer (LARC) has not been defined. This exploratory study aimed to evaluate whether the gut microbiome is associated with response to neoadjuvant SCRT followed by CAM and CAPOX. Methods We obtained a total of 77 fecal samples from 36 patients with LARC, including 17 assigned to the long-course chemoradiotherapy (LCRT) group and 19 to the SCRT group. Samples were collected at three time points: baseline, after radiotherapy, and after chemoimmunotherapy. DNA was extracted, followed by metagenomic sequencing to profile microbiota dynamics during neoadjuvant treatment. Results In this pilot analysis, we observed significant differences in the gut microbiota between the SCRT and LCRT treatment cohorts. Specifically, Bifidobacterium and Dorea were significantly enriched following completion of SCRT sequential CAM and CAPOX therapy. Further analysis revealed that the relative abundances of these two genera changed significantly only before and after the SCRT regimen, with no notable changes observed in the LCRT group. Preliminary ROC analysis suggested potential utility of these taxa for predicting treatment response, though validation in larger cohorts is needed. Conclusion The gut microbiome offers potential biomarkers that may stratify response to SCRT followed by CAM and CAPOX, representing a promising exploratory finding with potential clinical relevance.
