Join us for an important conversation with Dr. Andrew Hintel and Dr. Lauren Merz as we explore how the Duffy null phenotype shapes absolute neutrophil count (ANC) and what this means for clinical care and trial design. Although common among individuals of African, Middle Eastern, and North African ancestry, the Duffy null phenotype is often misunderstood, leading to unnecessary procedures, inappropriate dose modifications, and exclusion from potentially life-saving therapies.

Through real-world examples, we discuss how standard ANC cutoffs can disadvantage Duffy null patients, the implications for chemotherapy, immunosuppressive drugs, and clozapine, and how recent updates to Common Terminology Criteria for Adverse Events grading criteria intersect with this biology. The episode also highlights ongoing efforts, supported by ASH and the Doris Duke Foundation, to establish adult and pediatric reference intervals and promote more inclusive clinical trial practices.

This discussion will equip hematologists and oncologists with practical insights to better interpret neutrophil counts, advocate for equitable trial access, and optimize treatment decisions for patients with the Duffy null phenotype.

Learning Objectives:

1. Understand the ANC by Duffy Status Project: Describe the rationale behind reconsidering absolute neutrophil count (ANC) reference ranges based on Duffy status and its implications for patient care.

2. Apply Clinical Trial Recommendations: Identify key recommendations for including patients with Duffy-null associated neutrophil counts in clinical trials and explain why these changes are important for equitable trial design.

3. Utilize Educational Resources: Recognize the educational tools and resources available to support clinicians, researchers, and institutions in adopting updated ANC reference ranges and practices.

Clinical Pearls:

1. The Duffy null phenotype is found in 10% of people United States and results in an absolute neutrophil count lower limit of normal of ~1200/uL.

2. Clinical trials do not account for this variation which results in disparities in eligibility, systemic anticancer therapy administration, and adverse event reporting.

3. The American Society of Hematology strongly recommends obtaining Duffy status in all clinical trials