Targetable activating mutations are very frequent in GCB and ABC diffuse large B-cell lymphoma

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Diffuse Large B Cell Lymphoma (DLBCL) is a heterogeneous cancer with two main subtypes: germinal center B-cell-like (GCB) and activated B-cell-like (ABC).
• Activating mutations in BCR, NF-κB pathways, and epigenetic regulators like EZH2 are found in specific DLBCL subtypes.

Purpose of the Study:

• To analyze the frequency and distribution of mutations in five key genes (CD79A, CD79B, MYD88, CARD11, EZH2) in untreated de novo DLBCL.
• To investigate the correlation between these mutations and DLBCL subtypes.
• To assess the prognostic impact of NF-κB pathway mutations in ABC DLBCL patients treated with rituximab and chemotherapy.

Main Methods:

• Genomic DNA was extracted from 161 untreated de novo DLBCL patients.
• Mutational status of CD79A, CD79B, MYD88, CARD11, and EZH2 genes was analyzed using sequencing.
• DLBCL subtypes were determined, and mutation data was correlated with subtype and clinical outcome.

Main Results:

• 93 mutations were detected in 61 (38%) patients.
• MYD88 L265P mutation was exclusive to the ABC subtype (18 cases).
• EZH2 Y641 mutations were predominantly found in the GCB subgroup (15/62; 24%).
• Activating NF-κB pathway mutations in ABC DLBCL treated with rituximab plus chemotherapy were associated with unfavorable outcomes (3-year OS 26% vs. 67%).

Conclusions:

• Activating and targetable mutations are highly prevalent in DLBCL at diagnosis.
• Sequencing a limited set of genes can aid in tailoring optimal treatment strategies for DLBCL.
• The study highlights the potential for precision medicine in DLBCL management based on mutational profiles.