Application of the Second Revision of the International Staging System (R2-ISS) in the prognostic assessment of newly diagnosed multiple myeloma

Abstract

Objective: To investigate the prognostic value of the Second Revision of the International Staging System (R2-ISS) in patients with newly diagnosed multiple myeloma (NDMM) . Methods: The retrospective study was performed in 326 NDMM patients with immunomodulatory drugs and/or proteasome inhibitors as the first-line treatment attending the Department of Hematology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, China, from December 2012 to March 2022. The Kaplan-Meier method was used for the survival analysis, with the Log-rank test comparing the between-group differences and Cox proportional risk regression modeling A multifactorial analysis was performed. Results: ①326 patients were included in the study, 190 of whom were males. The median age was 63 years, and the median followup time was 37 months. R2-ISS can effectively predict prognosis, particularly for R-ISS Ⅱ patients. The median progression-free survival (PFS) time of R2-ISS Ⅰ, R2-ISS Ⅱ, R2-ISS Ⅲ, and R2-ISS Ⅳ was 52, 29, 20, and 15 months (P<0.001), while the median overall survival (OS) time was 91, 60, 44, and 36 months (P<0.001). Multifactor analysis revealed that ISS Ⅱ, ISS Ⅲ, del (17p), t (4;14), 1q+, LDH increased, and age >65 years old were independent negative prognostic factors for OS. ISS Ⅱ, ISS Ⅲ, del (17p), t (4;14), 1q+, and LDH were independent negative prognostic factors for PFS. ②The C-index score of R2-ISS was 0.724, higher than that of R-ISS (0.678), indicating high prediction efficiency. ③The median PFS for 1q+-related double-hit in R2-ISS Ⅲ and Ⅳ were 20, 15 months (P=0.084) and the median OS were 35, 36 months (P=0.786), respectively. In R2-ISS Ⅲ, there were twenty-seven cases of 1q+-related double-hit, sixty-one cases of 1q+ single abnormality, and sixty-eight cases with no 1q+. The median PFS for the three groups were 20, 18, and 21 months (P=0.974), while the median OS was 35, 47, and 56 months (P=0.042), respectively. Adjusting the assignment of 1q+ to 1, the median PFS and OS of different R2-ISS stages differed significantly after regrouping (P<0.001) . Conclusions: The prognostic stratification value of R2-ISS is higher than R-ISS, particularly in the highly heterogeneous R-ISS Ⅱ population. Adjusting the assignment of the 1q+-related double-hit can improve R2-ISS, which should be validated in future studies with multi-center and expanded cases.