The following article features coverage from the 2020 Gastrointestinal Cancers Symposium meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Although some clinical trials have linked prior exposure to commonly used antibiotics and antacids to worse subsequent immunotherapy (IO) efficacy, researchers determined that the receipt of these kinds of drugs within 30 to 60 days prior to the receipt of immunotherapies in advanced hepatocellular carcinoma (HCC) did not influence overall survival or overall response rate. Results of the retrospective chart review-based analysis, which included 95 patients with advanced HCC from a single academic medical center, were presented in a poster at the 2020 Gastrointestinal Symposium in San Francisco, California.

Because drugs such as antibiotics, proton pump inhibitors (PPIs), and histamine receptor antagonists (H2RAs) have been shown to influence the gut microbiome, investigators from the Tisch Cancer Institute and the Icahn School of Medicine at Mount Sinai in New York City, hypothesized that exposure to these medications 1 to 2 months before the receipt of IO could alter the responses seen in patients across the cohort.

Historical response rates to immunomodulators are less than 20% in advanced HCC, so the authors reasoned that this rate could feasibly be lower in patients who had received prior antibiotics or antacids.

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The study enrolled mostly male patients (85%), and the median patient age was 65 years. The cohort was racially diverse (31% White, 23% Black, 23% Asian, and 13% Hispanic), and 49%, 31%, and 11% of patients had underlying hepatitis C virus, hepatitis B virus, and nonalcoholic steatohepatitis (NASH), respectively. Eighty percent of the patients had cirrhosis.

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Within 60 days before the initiation of IO, 25 patients had received antibiotics, 40 patients had received PPIs, and 5 patients had received H2RAs (25 patients received neither antacids nor antibiotics). The majority of patients who received antibiotics also received a PPI (92%) and the median duration of antibiotic treatment was 5 days.

In univariate and multivariate analyses, exposure to these common drugs was found not to influence response to immunotherapy nor overall survival in this specific HCC disease group. “Larger observational studies or mechanistic studies are needed to clarify interactions between medications, the microbiome, and IO response,” the investigators wrote.

Disclosure: Some of the study authors disclosed financial relationships to pharmaceutical companies. For a full list of disclosures, please refer to the study abstract.

Read more of Cancer Therapy Advisor‘s coverage of the ASCO GI annual meeting by visiting the conference page.


Jun T, Dharmapuri S, Marron TU, et al. Effect of baseline medications on response to immunotherapy in hepatocellular carcinoma. J Clin Oncol. 2020;38(suppl 4):Abstract 484.