Tumor-resident Lactobacillus iners confer chemoradiation resistance through lactate-induced metabolic rewiring.

Tumor microbiota can produce active metabolites that affect cancer and immune cell signaling, metabolism, and proliferation. Here, we explore tumor and gut microbiome features that affect chemoradiation response in patients with cervical cancer using a combined approach of deep microbiome sequencing, targeted bacterial culture, and in vitro assays. We identify that an obligate L-lactate-producing lactic acid bacterium found in tumors, Lactobacillus iners, is associated with decreased survival in patients, induces chemotherapy and radiation resistance in cervical cancer cells, and leads to metabolic rewiring, or alterations in multiple metabolic pathways, in tumors. Genomically similar L-lactate-producing lactic acid bacteria commensal to other body sites are also significantly associated with survival in colorectal, lung, head and neck, and skin cancers. Our findings demonstrate that lactic acid bacteria in the tumor microenvironment can alter tumor metabolism and lactate signaling pathways, causing therapeutic resistance. Lactic acid bacteria could be promising therapeutic targets across cancer types.

Clostridioides difficile Infection in Cancer and Immunocompromised Patients: Relevance of a Two-step Diagnostic Algorithm and Infecting Ribotypes on Clinical Outcomes.

BACKGROUND: Patients with cancer are particularly vulnerable to Clostridioides difficile infection (CDI). Guidelines recommend a two-step diagnostic algorithm to differentiate carriers from CDI; however, there are limited data for this approach while including other confounding risk factors for diarrhea such as radiation, cytotoxic chemotherapy, and adoptive cell based therapies. METHODS: We conducted a prospective, non-interventional, single center, cohort study of cancer patients with acute diarrhea and C. difficile, identified in stools by nucleic acid amplification tests (NAAT) and culture. Fecal toxin A/B was detected by enzyme immunoassay (EIA) and isolates were ribotyped using 16s rRNA fluorescent sequencing. Patients were followed for 90 days to compare outcomes according to malignancy type, infecting ribotype, and EIA status. RESULTS: We followed 227 patients with a positive NAAT. Of these, 87% were hospitalized and 83% had an active malignancy. EIA was confirmed positive in 80/227 (35%) of patients. Those with EIA+ were older (60 ± 18 years vs 54 ± 19 years., P = .01), more likely to fail therapy [24/80 (30%) vs 26/147 (18%), P = .04] and experience recurrence [20/80 (25%) vs 21/147(14%), P < .05]. We found a low prevalence (22%) of ribotypes historically associated with poor outcomes (002, 018, 027, 56, F078-126, 244) but their presence were associated with treatment failure [17/50 (34%) vs 33/177 (19%), P = .02]. CONCLUSIONS: When compared to cancer patients with fecal NAAT+/EIA-, patients with NAAT+/EIA+ CDI are less likely to respond to therapy and more likely to experience recurrence, particularly when due to ribotypes associated with poor outcomes.