The role of cd5+ as aggressive biomarker in diffuse large b‐cell lymphoma

Background: Diffuse large B-cell lymphoma (DLBCL) is a clinical and biological heterogeneous subtype of lymphoma. The better knowledge of its biology let to identify some factors associated with worse outcomes. In this setting, the expression of CD5 emerged as a possible biomarker of lymphoma aggressiveness. Hereby we describe a single-center series of DLBCL with CD5 expression. Methods: We retrospectively analyzed patients with DLBCL expressing CD5 by immunohistochemistry (IHC) diagnosed from 2010 to 2022 at Institute Catalan of Oncology Hospitalet. For Kaplan-Meier analysis, relapse, progression or death were considered an event. Results: Among 559 total DLBCL patients registered, 25 (4.5%) were CD5-positive. At diagnosis, median age was 69 years (33–85), 12 (52%) were males, 15 (60%) had Ann Arbor stage III-IV, all patients had extranodal involvement (10 with >1 site), 8 (32%) presented B-symptoms, 14 (56 %) had IPI 3–5, and 10 (40%) presented bulky disease (>5 cm). LDH was elevated in 20 (80%) and beta2microglobuline in 16 (64%). Regarding histology, 60% were DLBCL NOS, 16% transformed DLBCL, 8% EBV-positive DLBCL, 8% leg-type, 4% double hit and 4% intravascular DLBCL. By IHC, 54% had non-germinal center phenotype according to Hans algorithm, 17 (71%) expressed MUM1, 10 (40%) expressed MYC 40%, 20 (80%) expressed Bcl2 50%, and 9/12 (75%) were double-expressors. Median Ki67 was 85% (range 30–100), P53 (median of 20%) was expressed in 5/10 (50%). MYD88 L265P mutation was detected in 2/5 (40%) cases. R-CHOP/R-CHOP-like was the most used treatment in first-line (22 patients), combined with radiotherapy in 6 patients (all with localized disease), and 3 (12%) patients received palliative regimens due to frailty. Treatment was not completed in 6 patients, mainly due to infectious complications. Complete response rate was 72%. With a median follow-up of 2 years (range 0–4), 7 (28%) patients progressed/relapsed at a median time of 11.1 months (1.4–18.9). The median progression-free survival and overall survival at 2 years were 53% (CI 95%, 31%-73%) and 66% (CI 95%, 44%-82%), respectively. Keywords: aggressive B-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers No conflicts of interests pertinent to the abstract.