# Fix the neutrophil count rule that excludes many people of African ancestry

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

## TL;DR

A majority of people of West African ancestry carry the Duffy-null variant, which lowers baseline neutrophil counts without raising infection risk. Trials apply a single neutrophil cut-off that wrongly labels them unfit, so protocols should use Duffy-specific thresholds; Duffy status is a cheap blood test.

## Summary

The Duffy-null phenotype (ACKR1 rs2814778 CC), carried by a majority of people of West African ancestry, is associated with lower baseline neutrophil counts without increased infection risk. Protocols would use Duffy-status-specific absolute neutrophil count thresholds (or exclude on infection history rather than ANC alone), and dose-modification rules for neutropenia would be reinterpreted accordingly. Duffy status is a cheap blood test.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Adopting Duffy-aware ANC thresholds will remove a leading cause of screen failure among Black patients in oncology trials and will not increase febrile neutropenia among those enrolled under the adjusted threshold.
- Rationale: Retrospective analyses attribute a substantial share of Black patients' trial ineligibility and chemotherapy dose reductions to the standard ANC cut-off, and the Duffy-null association with benign neutropenia is well established in haematology.
- Proposed test: A sponsor adopts Duffy-aware thresholds across its solid-tumour trials for two years; compare Black patient screen-failure rates and febrile neutropenia among those newly eligible against prior protocols.
- 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

- cancers: [Multiple myeloma](https://onco.cc/cancers/multiple-myeloma/), [Prostate cancer](https://onco.cc/cancers/prostate/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- bottlenecks: [Trials do not represent the people who get cancer](https://onco.cc/bottlenecks/b-trial-diversity/), [Trials enrol too few, too slowly](https://onco.cc/bottlenecks/b-trial-enrolment/)
- 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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