(DLBCL)
Patients with this subtype, dubbed “molecular high-grade” (MHG) DLBCL, were more likely to have germinal center B-cell-like (GCB) DLBCL, MYC rearrangements, and double-hit lymphoma.
When compared to other DLBCL patients, those with MHG DLBCL had inferior progression-free and overall survival.
Chulin Sha, PhD, of the University of Leeds (England), and colleagues reported these findings in the Journal of Clinical Oncology. The findings were published alongside a related editorial and a similar study from another group.
Dr. Sha and colleagues began their study by applying a previously developed gene expression classifier (Genome Med. 2015 Jul 1;7[1]:64) to 928 DLBCL patients enrolled in the REMoDL-B trial. REMoDL-B was designed to compare rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) to R-CHOP plus bortezomib (Hematol Oncol. 2017;35:130-1).
Dr. Sha and colleagues looked for somatic mutations in 400 REMoDL-B patient samples that were sequenced for a 70-gene panel.
The team also tested 360 samples for MYC, BCL2, and BCL6 chromosomal rearrangements using fluorescent in situ hybridization, and they tested 355 samples for MYC and BCL2 protein expression with immunohistochemistry.
Characteristics of MHG DLBCL
The researchers identified 83 REMoDL-B patients as having MHG DLBCL (9%). Most of the MHG patients had GCB DLBCL (90%), 48.6% had MYC rearrangements, and 36.1% had double-hit lymphoma.
Patients with MHG DLBCL had higher International Prognostic Index scores (P = .004), greater tumor bulk (P = .007), higher disease stage (P = .06), and higher lactate dehydrogenase levels (P less than .001) than patients with non-MHG DLBCL.
Although most MHG patients had GCB DLBCL, the researchers found key differences between patients with MHG DLBCL and non-MHG GCB DLBCL. MHG patients were significantly more likely than patients with non-MHG GCB DLBCL to have mutations in KMT2D, BCL2, MYC, and DDX3X. Additionally, some genes frequently mutated in GCB DLBCL — such as B2M, SGK1, and NFKBIA — were rare in MHG DLBCL.
Dr. Sha and colleagues also compared the MHG patients to 70 patients with Burkitt lymphoma (BL) who had been analyzed in a previous study (Genome Med. 2015 Jul 1;7[1]:64).
The researchers found that BL has more upregulated genes than GCB (2,483 genes) and MHG DLBCL (1,784 genes), and MHG DLBCL has more upregulated genes than GCB DLBCL (382 genes). The team observed a similar pattern with downregulated genes and said this suggests “MHG is an intermediate group but closer to GCB than to BL.”