THE PROGNOSTIC SIGNIFICANCE OF CD10+ MUM1+ GCB SUBTYPE OF DIFFUSE LARGE B-CELL LYMPHOMAS

PURPOSE - Diffuse Large B-Cell Lymphoma can be subclassified into the prognostically distinct groups of GCB and non-GCB using the immunohistochemical Hans algorithm. However, in real life, patients classified as GCB show differing outcomes even when treated with the same chemotherapy regimen. CD10 is a GCB marker, while MUM1 is a non-GCB marker, but Hans algorithm classifies CD10+ MUM1+ patients as GCB DLBCL. We explored whether CD10+ MUM1+ GCB DLBCL patients had different outcomes compared to rest of the GCB DLBCL patients.

METHODS - In this study, we retrospectively analyzed the clinical records of 427 DLBCL patients treated with standard chemo-immunotherapy at Kidwai Memorial Institute of Oncology, Bengaluru from 2013 to 2019. The clinical characteristics, response rate and overall survival of CD10+ MUM1+ GCB group was compared with MUM1-ve GCB group and non-GCB group.

RESULTS - Among the patients studied, 187 (43%) patients were of GCB subtype, whereas 240 (57%) patients belonged to the non-GCB subtype. Additionally, 61 (14.3%) patients were of the CD10+ MUM1+ GCB immune-phenotype. No significant differences could be demonstrated in the clinical characteristics of CD10+ MUM1+ GCB and MUM1- GCB patients. Patients with CD10+ MUM1+ GCB subtype exhibited a significantly inferior response rate compared to those with MUM1- GCB subtype (81% versus 92%; p=0.04). Although, both non-GCB and CD10+ MUM1+ GCB subtypes displayed diminished overall survival in comparison to MUM1- GCB patients, (non-GCB = 33 months, CD10+ MUM1+ GCB = 33 months and MUM1-ve GCB = 40.4 months, p = 0.21) it did not reach statistical significance

CONCLUSION - CD10+ MUM1+ GCB patients may be prognostically more similar to non-GCB patients, as suggested by the inferior response rates and numerically inferior OS compared to other GCB patients. This needs further confirmation in prospective studies.