STOP: Broad-Spectrum Antibiotics During Ovarian Cancer Chemotherapy

The Conventional Approach#

OC patients receiving platinum-based chemotherapy are immunocompromised and at risk of infection. Broad-spectrum antibiotics are commonly prescribed prophylactically or therapeutically.

Why This Is Counterproductive#

Two independent preclinical studies converge on the same conclusion: antibiotic-induced microbiome depletion actively worsens OC outcomes.

1. Increased Tumor Growth and Cisplatin Resistance (Hawkins 2022)#

Antibiotic-induced dysbiosis in OC models increased tumor growth AND enhanced cisplatin-induced stemness, enriching cancer stem cell populations. The gut microbiome is required for immune surveillance of OC stem cells.

ABX depletes the protective metabolites indole-3-propionic acid (IPA) and indoxyl sulfate—both restored by FMT.^{[1]Hawkins 2022 — Unintended Consequences of Antibiotic Therapy on the Microbiome Delivers a Gut Punch in Ovarian CancerHawkins SM, Nephew KP · 2022Open reference 1 ↓}

2. Abolished Chemosensitization (Tian 2026)#

Antibiotic depletion of gut microbiota abolished the chemosensitizing effects of Tripterygium glycosides, which work by inducing ferroptosis via Keap1-Nrf2-GPX4 axis inhibition. The microbiome is required for this drug to work.^{[2]Tian et al. 2026 — Tripterygium Glycosides and Lactobacillus paracasei Sensitize EOC to Cisplatin via Keap1-Nrf2-GPX4 PathwayTian M, Zeng X, Zhong Y et al. · 2026Open reference 2 ↓}

Alternative Approach#

1. Use narrowest-spectrum antibiotic possible when antibiotics are medically necessary
2. cobalt (Co)-administer probiotics (separated by 2+ hours from antibiotics)
3. Consider FMT post-antibiotic course to restore protective metabolite production
4. Monitor for microbiome restoration after antibiotic courses before continuing chemotherapy