Incidence and predictors of severe infectious complications in relapsed//refractory multiple myeloma treated with lenalidomide and dexamethasone (Rd) regimen ― a single-center, retrospective, real-life study.

Introduction: Relapsed/refractory multiple myeloma (RRMM) is a challenging setting for management and treatment. In Poland, a substantial fraction of RRMM patients is currently treated with lenalidomide and dexamethasone (Rd). Establishing predictors of treatment-related complications and poor response is crucial for further optimal therapeutic decision-making. Material and methods: This retrospective study included all patients who received the Rd regimen according to the Ministry of Health's drug reimbursement program (B.54) between January 2017 and December 2021 in the Department of Hematology, Medical University of Lodz, Poland. Results: The study group consisted of 174 patients, and the mean age was 67.3 ± 9.0 years. The majority of patients (63.2%) received the Rd at the first relapse//progression. The median PFS was 12.6 months, and the median OS was 22.3 months. The overall response rate was 64.1%, 12.7% achieved complete response (CR), and 20.4% had a very good partial response (VGPR). In multivariate Cox regression analysis for PFS, ISS 3 (HR 1.8, 95% CI: 1.2-2.7, p = 0.0062) and CR/VGPR after 6. cycle (HR 0.4, 95% CI: 0.2-0.9, p = 0.0222) were independent prognostic factors. Similarly, ISS 3 (HR 2.1, 95% CI: 1.3-3.3, p = 0.0012) was related to poorer OS, whereas CR//VGPR achievement was related to improved OS (HR 0.4, 95% CI: 0.2-0.9, p = 0.0238). The most prevalent adverse events in the study group were serious infections (31.0%), neutropenia (28.7%), thrombocytopenia (18.4%), anemia (18.1%) and thromboembolic events (11.5%). In multivariate logistic regression analysis, hypoalbuminemia (OR 4.2, 95% CI: 1.6-11.2, p = 0.0039), ASCT before Rd (OR 2.6, 95% CI: 1.0-6.7, p = 0.048) and anemia (OR 5.0, 95% CI: 1.8-14.0, p = 0.002) were independent factors related to the occurrence of serious infections. Conclusions: RRMM patients with ISS 3 and who did not achieve CR/VGPR have inferior outcomes following Rd and should be candidates for novel drug administration or enrolled in clinical trials. Patients after ASCT, with hypoalbuminemia or anemia during Rd treatment are at risk of serious infectious complications. [ABSTRACT FROM AUTHOR]