Global outcomes and prognosis for relapsed/refractory mature T-cell and NK-cell lymphomas: results from the PETAL consortium

Variances in global access to drugs and treatment practices make it challenging to understand the benefit of contemporary therapies in patients with relapsed and refractory (R/R) mature T-cell and natural killer–cell lymphomas (MTCL and MNKCL). We conducted an international retrospective cohort study of 925 patients with R/R MTCL and MNKCL. In peripheral T-cell lymphoma–not otherwise specified and anaplastic lymphoma kinase–negative anaplastic large cell lymphoma (ALK– ALCL), patients with relapsed lymphoma demonstrated a superior median overall survival (OS) relative to refractory from the time of second-line treatment. We identified several independent predictors of OS for R/R lymphoma including age >60 years, primary refractory disease, histological subtype other than angioimmunoblastic T-cell lymphoma (AITL), extranodal sites >1, Ki67 ≥40%, and absolute lymphocyte count less than the lower limit of normal. A multivariable model incorporating these formed the basis for a prognostic index for R/R TCL, in which patients are stratified into low-risk (0-1 risk factor), intermediate-risk (2-3 risk factors), or high-risk (≥4 risk factors) groups, which were associated with 3-year OS of 57.14%, 23.3%, and 7%, respectively. Patients received either a "novel" single agent (SA; 35%) or cytotoxic chemotherapy (CC; 60%) for their second-line treatment. Higher progression-free survival was observed with SA over CC for the entire cohort with a higher 3-year OS in AITL and ALK– ALCL. Among the SA, small-molecule inhibitors demonstrated OS advantage relative to CC in AITL. Our results highlight continued efficacy of novel drugs globally and the potential of a new prediction model in informing heterogeneous prognosis within the R/R population of MTCL and MNKCL.