# Parallel real-world cohorts for sicker patients alongside every pivotal trial

Source: https://onco.cc/ideas/idea-tr1-parallel-comorbidity-cohorts/  
OnCo record `idea-tr1-parallel-comorbidity-cohorts` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Instead of excluding sicker patients entirely, trials would run a side group for them, receiving the new drug with closer monitoring, so we learn how it behaves in the people who will actually get it.

## Summary

Registrational trials open a non-randomised parallel cohort for patients who fail the main eligibility on performance status (ECOG 2), organ function, or comorbidity, treated with the experimental regimen under a pre-specified safety and dose-adjustment plan, with PK sampling. Data are analysed separately and included in the label as descriptive evidence. Precedent: NCI organ-dysfunction working group studies and some sponsor expansion cohorts.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Parallel cohorts will generate dosing and safety guidance for ECOG 2 and organ-impaired patients at approval in most programmes, and real-world toxicity in those groups will fall as clinicians use it.
- Rationale: ECOG 2 patients are a substantial share of real-world recipients and are almost absent from trials; clinicians extrapolate from fitter patients with predictable harm.
- Proposed test: Sponsors open parallel cohorts in ten registrational trials; measure enrolment feasibility, the fraction generating label text, and subsequent real-world outcomes in the affected groups.
- Maturity: early-clinical
- Actor: industry

## Sources

- Bottleneck evidence (Trials do not represent the people who get cancer): Loree et al., Disparity of race reporting and representation in trials leading to cancer drug approvals (JAMA Oncology 2019): https://doi.org/10.1001/jamaoncol.2019.1870

## Connected records

- technologies: [Geriatric assessment](https://onco.cc/technologies/geriatric-assessment/)
- bottlenecks: [Older and multimorbid patients are excluded and undertreated](https://onco.cc/bottlenecks/b-aging-comorbidity/), [Trials do not represent the people who get cancer](https://onco.cc/bottlenecks/b-trial-diversity/)
- key papers: [Disparity of Race Reporting and Representation in Clinical Trials Leading to Cancer Drug Approvals From 2008 to 2018](https://onco.cc/key-papers/paper-loree-jama-oncol/)

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