A prognostic index predicting survival in transformed Waldenström macroglobulinemia
Éric Durot, Lukshe Kanagaratnam, Saurabh Zanwar, Efstathios Kastritis, Shirley D’Sa, Ramón García‐Sánz, Cécile Tomowiak, Bénédicte Hivert, Elise Toussaint, Caroline Protin, Jithma P. Abeykoon, Thomas A. Guerrero-Garcia, Gilad Itchaki, Josephine M. I. Vos, Anne‐Sophie Michallet, Sophie Godet, Jehan Dupuis, Stéphane Leprêtre, Joshua Bomsztyk, Pierre Morel, Véronique Leblond, Steven P. Treon, Meletios Α. Dimopoulos, Prashant Kapoor, Alain Delmer, Jorge J. Castillo
Abstract
Histological transformation into diffuse large B-cell lymphoma is a rare complication in patients with Waldenström macroglobulinemia (WM) usually associated with a poor prognosis. The objective of this study was to develop and validate a prognostic index for survival in transformed WM patients. Through this multicenter, international collaborative effort, we developed a scoring system based on data from 133 patients with transformed WM who were evaluated between 1995 and 2016 (training cohort). Univariate and multivariate analyses were used to propose a prognostic index with 2-year survival after transformation as an end-point. For external validation, a data set of 67 patients was used to evaluate the performance of the model (validation cohort). By multivariate analysis, three adverse covariates were identified as independent predictors of 2-year survival after transformation: elevated serum LDH (2 points), platelet count < 100 x 109/L (1 point) and any previous treatment for WM (1 point). Three risk groups were defined: low-risk (0-1 point, 24% of patients), intermediate-risk (2-3 points, 59%, hazard ratio (HR) = 3.4) and high-risk (4 points, 17%, HR = 7.5). Two-year survival rates were 81%, 47%, and 21%, respectively (P < 0.0001). This model appeared to be a better discriminant than the International Prognostic Index (IPI) and the revised IPI (R-IPI). We validated this model in an independent cohort. This easy-to-compute scoring index is a robust tool that may allow identification of groups of transformed WM patients with different outcomes and could be used for improving the development of risk-adapted treatment strategies.