SUBTYPES OF MATURE T AND NK CELL LYMPHOMAS ACCORDING TO 2016 WHO CLASSIFICATION. PRELIMINARY REPORT OF THE INTERNATIONAL PROSPECTIVE T‐CELL PROJECT 2.0

Abstract

Introduction: Mature T and NK-cell lymphomas represent a heterogeneous group of lymphoid disorders (29 subtypes according to the 2016 WHO classification) arising from mature T cells of post-thymic origin with different morphological characteristics, phenotypes, and clinical presentation. Following the success of the T Cell Project (TCP), which allowed the analysis of more than 1,500 cases of peripheral T-Cell lymphomas (PTCLs) collected prospectively in 18 Countries, in 2018 the TCP 2.0 was launched. Here we report the global distribution of PTCLs, from the cases registered so far based on the locally established histological diagnosis. Methods: The TCP2.0 (ClinicalTrials.gov Identifier: NCT03964480) is a prospective, international, observational study which adapts to changes made in the new WHO classification. Results: Since the beginning of the study (October 2018), 648 patients with newly diagnosed PTCL were registered by 75 active centers across 14 countries. Of these data, 594 patients have been validated by the centralized trial office. Overall, PTCL-NOS, Anaplastic large cell lymphoma (ALCL) ALK-negative, and Angioimmunoblastic T-cell lymphoma (AITL), represent the most frequent subtypes, representing 31.3%, 18,9% and 13,5% of cases, respectively. As reported in Table 1, PTCL-NOS represents the most frequent subtype worldwide, whereas Adult T-cell leukemia/lymphoma was more frequent in Brazil, AITL and ALCL ALK-negative in Australia/ India, and ALCL ALK-positive in North America and Europe. Extranodal NK/T-cell lymphoma, nasal type was relatively frequent in Brazil and quite rare in the other Latin America Countries. Finally, many sub-types represent less than 5% of cases in all geographic areas. Conclusions: The TCP2.0 continues to recruit very well, despite the difficulties linked to the COVID-19 pandemic, and may represent a useful resource for the prospective study of this group of rare lymphomas.