Evaluation of treatment-related toxicity and survival outcomes in patients with multiple myeloma receiving lenalidomide maintenance after consoli̇dati̇on therapy or autologous transplantati̇on

Objective: Multiple myeloma is a malignant plasma cell disorder originating from the bone marrow. In recent years, survival rates have been steadily increasing with the introduction of new drugs. In this study, we aimed to evaluate treatment-related toxicity and survival outcomes in patients with multiple myeloma receiving maintenance lenalidomide therapy after consolidation therapy or autologous stem cell transplantation. Method: This study was conducted with 85 patients who were diagnosed with multiple myeloma and received maintenance lenalidomide therapy at the Hematology Clinic of Pamukkale University Faculty of Medicine Hospital between January 1, 2010, and January 1, 2021. Patients' age, gender, comorbid diseases, date of diagnosis, stage of the disease, laboratory data at the time of admission, plasma cell ratio in the bone marrow, type of myeloma, treatments received by the patients, responses to these treatments, responses before and after autologous stem cell transplantation (ASCT), start date of maintenance lenalidomide therapy, duration of maintenance lenalidomide therapy, side effects related to lenalidomide, whether dose reduction was necessary during treatment, whether there was an increase in the depth of response during maintenance lenalidomide therapy, whether there was a relapse during follow-up, survival data, and observed toxicity profiles were evaluated. The primary endpoints were progression-free survival (PFS) and overall survival (OS), and the secondary endpoint was time to next treatment (TTNT). Results: It was observed that the plasma cell ratio in the bone marrow biopsy at the time of diagnosis was associated with shorter PFS and OS. It was determined that stage 1 ISS was associated with better PFS and OS compared to other stages. During maintenance lenalidomide therapy, it was seen that dose reduction might be necessary due to neutropenia, renal failure, and increases in liver function tests. It was found that both ASCT treatment and maintenance lenalidomide therapy could increase the depth of response. The most common side effects related to maintenance lenalidomide therapy were hematological, followed by infections and skin toxicities in the second and third places, respectively. A correlation was found between the duration of maintenance therapy and PFS and OS. Conclusion: Progression free survival and overall survival improved with maintenance lenalidomide treatment. Side effects that may develop during treatment should be taken into consideration, and prophylactic treatments should be given when necessary. Further studies are needed to evaluate the relationship between lenalidomide-related side effects and overall survival and progression free survival. Keywords: Multiple myeloma, lenalidomide, maintenance therapy, toxicity, side effects, overall survival, progression-free survival