Mature T and NK cell lymphomas classified according to 2016 WHO classification. A report of 741 cases registered in the International Prospective T‐cell Project 2.0.

Introduction: Mature T and NK-cell lymphomas represent a heterogeneous group of rare lymphoid disorders arising from mature T cells of post-thymic origin. The T-cell Project 2.0 (TCP2) was launched in 2018 with the aim of better understanding this group of rare disorders, capturing a real-life snapshot of the evolving landscape of T-cell lymphoma biology, treatment strategies, and outcome. Here we report preliminary data on histotype distribution, disease characteristics, front line treatment, and short-term outcome of patients registered between 2018 and 2021. Methods: The TCP2 (ClinicalTrials.gov Identifier: NCT03964480) is a prospective, longitudinal, international, observational study of patients with Peripheral T-cell lymphoma (PTCL). For this analysis we considered cases based on the diagnosis made locally according to the WHO2016 classification. The study was approved by each participating center and required patients to sign informed consent. Results: Between October 2018 and December 2021, 741 eligible cases with newly diagnosed PTCLs were registered by 94 Institutions across 17 Countries. Overall, PTCL-NOS, AITL, ALCL ALK-, ALCL ALK+, ENKTCL, and ATLL resulted the most frequent 6 subtypes, accounting for 91% of cases, while the remaining 9% were represented by few cases of 13 different subtypes. Of note, only 16 cases (2.1%) were classified according to entities not considered in the previous WHO 2008 classification. The median age at diagnosis was 57 years (18–93), 56.5% of patients were male, the presence of systemic symptoms was reported in 30% of cases, 7.4% had ECOG-PS 3–4, 71% advanced disease and 36.6% bone marrow involvement. Overall, 88% were treated with combination chemotherapy and 28% of patients with advanced stage disease in complete or partial remission after chemotherapy were consolidated with high dose therapy and stem cell transplantation. After a median follow-up of 21 months, the 2-year PFS and OS of the whole series were 38% and 52%, respectively. At the same time point, the PFS and OS (in brackets) were: PTCL-NOS (24% and 43%); AITL (40% and 50%); ENKTL (44% and 53%); ALCL ALK- (52% and 67%); ALCL ALK+ (71% and 85%) and ATLL (14% and 27%). Comparing the distribution of cases enrolled in the present study with those in the previous TCP1 (2008–2018), we found a 6% and 3% decrease in the frequency of PTCL-NOS and EATL, respectively, whilst the frequency of other histotypes remained almost unchanged. Of note, no statistically significant differences emerged in terms of PFS and OS for the comparable histotypes of TCP1 and TCP2. Conclusions: Based on the analysis of this large series of cases of PTCL prospectively registered in the TCP2, it seems “Nothing new under the sun”: no improvement in terms of outcome and a very limited effect of the WHO2016 in classification of cases in the real world. The research was funded by: Angela Serra Association for Cancer Research Keywords: Aggressive T-cell non-Hodgkin lymphoma, Pathology and Classification of Lymphomas No conflicts of interests pertinent to the abstract.