BRAF Alterations in Chronic Lymphocytic Leukemia: Genomic Landscape, Co-Mutation Patterns, and Clinical Relevance

Area of Science:

• Hematology
• Oncology
• Genetics

Background:

• BRAF alterations are infrequently observed in chronic lymphocytic leukemia (CLL).
• Broad genomic profiling reveals BRAF alterations as a component of MAPK-pathway dysregulation in CLL.
• Understanding BRAF's role requires distinguishing between chemoimmunotherapy and targeted therapy eras.

Purpose of the Study:

• To review the frequency, mutation spectrum, co-mutation patterns, and clinical implications of BRAF alterations in adult CLL.
• To differentiate findings in chemoimmunotherapy-dominant cohorts versus targeted-therapy-era cohorts.
• To clarify the role of BRAF alterations in CLL progression and treatment resistance.

Main Methods:

• Systematic review of published studies on BRAF alterations in CLL.
• Analysis of BRAF mutation frequencies in unselected and selected CLL populations.
• Examination of BRAF alterations in relation to treatment response and clinical endpoints across different therapeutic eras.

Main Results:

• BRAF mutations occur in ~2-6% of CLL cases, with higher rates in enriched populations.
• In chemoimmunotherapy-era CLL, BRAF alterations impact time-to-treatment endpoints more than overall survival.
• In targeted-therapy-era CLL, BRAF alterations are associated with relapse after BTK-, PI3K-, or BCL2-targeted therapies and are more frequent in Richter transformation.

Conclusions:

• BRAF alterations in CLL are best understood within the RAS-RAF-MAPK-ERK signaling context, not as a V600E-driven disease.
• BRAF is a biologic and resistance-relevant annotation, not a standalone prognostic biomarker or routine therapeutic target in CLL.
• BRAF's clinical relevance is highest in trisomy 12-enriched disease, complex genomics, Richter transformation, and treatment-emergent relapse.