# Randomise a cheap antihistamine alongside immunotherapy

Source: https://onco.cc/ideas/idea-reg-antihistamine-plus-io-trial/  
OnCo record `idea-reg-antihistamine-plus-io-trial` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Patients who happened to take common allergy pills during immunotherapy seemed to live longer in a large records study. A simple randomised trial would show whether the pills really help.

## Summary

A 2022 analysis of MD Anderson records (Li and colleagues, Cancer Cell) found that H1-antihistamine use during checkpoint inhibitor therapy was associated with improved survival in melanoma and lung cancer, with mechanistic work suggesting histamine-HRH1 signalling in macrophages drives T-cell dysfunction. Antihistamines cost pennies and are extremely safe. The proposal is a placebo-controlled randomised trial of a non-sedating H1-antihistamine (for example fexofenadine or loratadine) added to standard checkpoint inhibitor therapy in non-small cell lung cancer, with a plasma histamine biomarker sub-study.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Adding an H1-antihistamine to first-line checkpoint inhibitor therapy improves progression-free survival with a hazard ratio of 0.8 or better, with the effect concentrated in patients with high plasma histamine.
- Rationale: The observational effect size was large, a mechanism has been demonstrated in mice, and the intervention has essentially no cost or toxicity, making the expected value of a trial very high even at modest prior probability.
- Proposed test: Phase 2/3 randomised double-blind trial of roughly 600 patients with NSCLC starting pembrolizumab-based therapy, PFS primary endpoint, biomarker-stratified analysis.
- Maturity: preclinical-evidence
- Actor: research

## Sources

- Bottleneck evidence (No incentive to repurpose cheap drugs): Pantziarka et al., The Repurposing Drugs in Oncology (ReDO) Project (ecancer 2014): https://doi.org/10.3332/ecancer.2014.442

## Connected records

- cancers: [Melanoma](https://onco.cc/cancers/melanoma/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- drugs: [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- institutions: [MD Anderson Cancer Center](https://onco.cc/institutions/md-anderson/)
- bottlenecks: [No incentive to repurpose cheap drugs](https://onco.cc/bottlenecks/b-generic-repurposing/), [No one can predict who responds to immunotherapy](https://onco.cc/bottlenecks/b-immunotherapy-response/)
- key papers: [KEYNOTE-189: pembrolizumab plus chemotherapy as first treatment for non-squamous lung cancer without a driver mutation](https://onco.cc/key-papers/paper-keynote-189-nejm-2018/), [The Repurposing Drugs in Oncology (ReDO) Project](https://onco.cc/key-papers/paper-pantziarka-ecancermedicalscience/)

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