Common Medications May Sabotage Cancer Immunotherapy

Immune Checkpoint Inhibitors (ICIs) have revolutionised the treatment of cancers like malignant melanoma and lung cancer since their global approval in 2011. However, response rates vary, and scientists have increasingly looked to the gut microbiome—the complex community of bacteria residing in our digestive tract—for answers. A comprehensive meta-analysis of 69 studies involving over 22,000 patients has now highlighted a crucial interaction: common medications may be interfering with these life-saving therapies.

The research indicates that patients taking antibiotics or proton pump inhibitors (PPIs)—drugs typically used to reduce stomach acid—alongside ICIs experienced significantly poorer outcomes. Specifically, the data showed lower overall survival and progression-free survival rates, particularly when antibiotics were administered within three months of starting therapy. The disruption these drugs cause to the gut’s bacterial ecosystem appears to blunt the immune system's ability to fight the tumour. In a promising twist, however, probiotic supplementation was associated with improved efficacy metrics, suggesting that carefully managing our internal flora could be key to optimising future cancer care.