OnCo
ideasIdea

Capture diet, fibre and antibiotic exposure in every immunotherapy pivotal trial

Gut bacteria appear to influence whether immunotherapy works, and diet and antibiotics shape gut bacteria. Yet almost no drug trial records what patients ate or which antibiotics they took. Recording it would cost almost nothing.

Fibre intake, probiotic use, antibiotics and proton-pump inhibitors are each associated with checkpoint-inhibitor outcomes in observational cohorts, but the data come from single centres with recall questionnaires. Pivotal trials enrol tens of thousands of patients under protocol with concomitant medication logs already captured; adding a short validated diet screener and banking a baseline stool sample would generate the largest and cleanest dataset on host factors in immunotherapy, and allow stratified or covariate-adjusted analyses that could explain part of the variability in response.

Hypothesis
Across pooled pivotal checkpoint-inhibitor trials, baseline fibre intake and peri-treatment antibiotic exposure are independent predictors of progression-free survival with effect sizes comparable to PD-L1 expression, and adjusting for them reduces between-trial heterogeneity.
Rationale
Regulators already require concomitant medication recording; FDA and EMA have encouraged patient-reported outcome and biomarker collection. A 10-item diet screener and a stool kit add minutes and a few hundred dollars per patient against trial costs of tens of thousands.
What would test it
Pilot in two ongoing cooperative-group immunotherapy trials with pre-specified analysis; if predictive value is confirmed, FDA and EMA guidance recommending standardised diet and antibiotic capture in immuno-oncology trials, with pooled analysis through Project Data Sphere or similar.
Maturity
speculative
Who has to act
regulator
Cost to try
Small (under $1M)
Years to first evidence
3
Bottlenecks it attacks
  • No one can predict who responds to immunotherapy · Checkpoint drugs cure some patients and do nothing for most. We still cannot tell the two apart before treating.
  • Trial design, endpoints and cost · A phase 3 trial takes years and hundreds of millions of dollars, and often answers a question that has already moved on.
  • Data silos · Records, scans, genomes and outcomes sit in separate systems that cannot talk. Every patient's experience is lost to the next.

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