Four genetic subtypes of diffuse large B-cell lymphoma (DLBCL) showed multiple distinct mutations, gene expression signatures, and treatment responses, researchers reported.
The findings “may provide a conceptual edifice on which to develop precision therapies for these aggressive cancers,” Roland Schmitz, PhD, and his associates wrote in the New England Journal of Medicine.
Other DLBCL studies have focused on individual mutations, but therapeutic response probably hinges on “constellations of genetic aberrations,” wrote Dr. Schmitz of the National Cancer Institute and his associates.
Therefore, they used exome and transcriptome sequencing, deep amplicon resequencing of 372 genes, and DNA copy-number analysis to analyze 572 fresh-frozen DLBCL biopsy specimens, nearly all of which were treatment-naïve.
This multiplatform approach yielded four genetic subtypes: MCD, so named for its co-occurring MYD88L265P and CD79B mutations; BN2, which has BCL6 fusions and NOTCH2 mutations; N1, which has NOTCH1 mutations; and EZB, which has EZH2 mutations and BCL2 translocations. Most MCD and N1 specimens were activated B-cell–like (ABC) tumors, EZB specimens were primarily germinal-center B-cell–like (GCB) tumors, and BN2 specimens included ABC, GCB, and unclassified cases.
A closer look at 119 previously untreated patients linked genetic subtypes with significant differences in progression-free survival (P less than .0001) and overall survival (P = .0002) following R-CHOP or CHOP-like chemotherapy.
The BN2 and EZB subtypes “[had] much more favorable outcomes than the MCD and N1 subtypes,” Dr. Schmitz and his associates said. “Analysis of genetic pathways suggested that MCD and BN2 DLBCLs rely on ‘chronic active’ B-cell receptor signaling that is amenable to therapeutic inhibition.”