Prevalence and Prognostication of CD5+ Mature T-Cell Lymphomas.

Simple Summary: T-cell lymphomas are hematologic cancers that are difficult to manage due to their aggressive nature and poor response to traditional chemotherapies. Response rates are unpredictable even in the era of novel therapeutics, and there has yet to be a clinically validated cellular marker associated with response rates or treatment outcomes. CD5 is a cellular marker that has been associated with poor outcomes in other cancers but has not been well established in T-cell lymphoma. This study confirmed that CD5 has a high prevalence in T-cell lymphomas and is associated with poor prognostic markers such as advanced age, bone marrow involvement, and poor functional status. Additionally, CD5 was associated with inferior survival in T-follicular cell lymphoma and adult T-cell lymphoma. These results suggest that CD5 is associated with worse prognosis in T-cell lymphomas and may be a potential therapeutic target in future studies. Background: T-cell lymphomas (TCLs) are a group of heterogenous cancers with poor rates and duration of response. There remains a great challenge in risk stratification of these cancers. Cluster of differentiation (CD) 5 has shown prognostic implication in many subtypes of B-cell lymphoma; however, its role in TCLs is not known. Methods: We performed a single-institution retrospective analysis of newly diagnosed patients with TCL. CD5 positivity was determined based on positive results via immunohistochemistry and/or flow cytometry. We used univariate and multivariable analysis of biological factors to assess their association with survival outcomes. Results: A total of 194 patients with TCL spanning 14 subtypes were identified. CD5 positivity was noted in 63% of patients, with the highest proportion of CD5 expression in TFH TCL (93.9%), PTCL-NOS (82.9%), and ATLL (77.8%) (p = 0.00004). Older age at diagnosis (p = 0.001), stage III or IV disease (p = 0.05), and bone marrow involvement (p = 0.003) were also associated with CD5 expression. Complete response rates were numerically lower in patients with CD5+ TCL across all subtypes. OS/PFS was not statistically associated with CD5 status in the overall cohort; however there was significantly decreased OS in CD5+ TFH TCL (p = 0.04) and CD5+ ATLL (p = 0.04) patients. Conclusions: This study represents the first to examine CD5 expression as a prognostic biomarker for outcomes in TCL. The frequent expression of CD5 in the most common nodal TCL in the Western world underpins its potential as an attractive target for cellular therapies. Confirmation of these findings in a larger cohort and investigation of potential pathophysiological mechanisms explaining our observations are planned. [ABSTRACT FROM AUTHOR]