Regular Article CLINICAL TRIALS AND OBSERVATIONS A prospective study of mediastinal gray-zone lymphoma

• MGZL with pathologic features in between NSHL and PMBL is very rare and most frequently occurs in young patients. • A prospective study of DA-EPOCH-R without mediastinal radiation in MGZL demonstrated an inferior outcome compared to patients with PMBL. MediastinalB-cell lymphomaspresent in themediastinumandaremost frequent in young patients. Nodular sclerosis Hodgkin lymphoma (NSHL) and primary mediastinal B-cell lymphoma (PMBL) are the common types, whereas mediastinal gray-zone lymphoma (MGZL) is extremely rare and has pathological features intermediate between NSHL and PMBL. The indeterminate pathobiology of MGZL has led to uncertainty regarding therapeutic strategy, and its clinical characteristics and treatment have not been characterized. We conducted a prospective study of infusional dose-adjusted etoposide, doxorubicin, and cyclophosphamide with vincristine, prednisone, and rituximab (DA-EPOCH-R) and filgrastim in untreated MGZL. We analyzed biomarkers of outcome and compared their clinical and biological characteristics to PMBL. Twenty-four MGZL patients had a median age of 33 years (range, 14 to 59 years), and 46% had mediastinal masses ‡10 cm. At 59 months median follow-up, the event-free survival and overall survival were 62% and 74%, respectively. The serum absolute lymphocyte count, the presenceof tumor-infiltratingdendritic cells,CD15expressionon themalignantcells, and tumor morphology were biomarkers of outcome in MGZL. Compared with PMBL, MGZL patientsweremore likely to bemale, expressCD15, have lower expressionofCD20, andhave aworseoutcome.DA-EPOCH-R alone is effective in MGZL. The trial was registered at ClinicalTrials.gov (NCT00001337). (Blood. 2014;124(10):1563-1569)