Retrospective evaluation of patients with multiple myeloma who underwent autologous stem cell transplantation

Objective: Autologous stem cell transplantation (ASCT) is a standard and important treatment for young or fit patients with multiple myeloma (MM). In this study, we performed a retrospective review of patients diagnosed with MM who underwent ASCT in our newly opened adult stem cell transplant center between October 2019, when the first transplant was performed, and December 2022. Material and Method: Between October 2019 and December 2022, 112 MM patients who underwent autologous stem cell transplantation at the Adult Stem Cell Transplant Center of Ondokuz Mayıs University Faculty of Medicine Hospital were included in the study. The follow-up of the patients was terminated in April 2023. Patients'myeloma type, international staging system (ISS) stage, chemotherapy regimen and number of cycles received before transplantation, presence of renal involvement, bone marrow cellularity and degree of fibrosis, stem cell collection regimen for mobilization, pre-transplant hemoglobin, white blood cell, platelet count, pre-ASCT preparation regimen, neutrophil and platelet engraftment times, length of hospitalization, complications that developed during this period, post-transplant responses, relapse status, progression-free survival and overall survival rates were analyzed. Results: Of the patients, 56.3% (n=63) were male and 43.8% (n=49) were female; the median age of the patients was 60 years. After induction therapy before autologous stem cell transplantation, 24.1% (n=27) had complete response (CR), 66.1% (n=74) had very good partial response (VGPR), 8% (n=9) had partial response (PR), 0.9% (n=1) had stable disease (SD) and 0.9% (n=1) had progressive disease (PD). The median number of CD34 stem cells collected was 4.66x10 6 /kg (min: 2.67x10 6 /kg - max: 24.9x10 6 /kg). Post-ASCT responses were CR in 33% (n=37), VGPR in 58.9% (n=66), PR in 1.2% (n=2), and PD in 6.3% (n=7). Median engraftment times were 11 days for neutrophils and 13 days for platelets. While 30.4% (n=34) of patients had no complications, the most common complication was neutropenic fever. The median follow-up period calculated after ASCT was 14 months (range 4-40 months). The median progression-free survival (PFS) for the entire group was 23.8 months, while overall survival (OS) was not reached. Expected 5-year PFS was 61.6% and expected 5-year OS was 88.6%. When the factors affecting the PFS were analyzed, ISS stage of the disease (p=0.034) and the response before ASCT (p=0.022) were found have a statistically significant effect on PFS. When the factors affecting the overall survival were analyzed, ISS stage of the disease (p=0.046) and the response received prior to ASCT (p=0.008) were found to be statisticaly significant. Conclusion: ASCT remains an indispensable part of the treatment of patients with previously untreated MM. The depth of response and the stage of the disease prior to ASCT are associated with good long-term outcomes. Our study is in line with the literature and current data and demonstrated that ASCT is still important in patients with newly diagnosed MM and that pre-transplant response and disease stage are associated with survival. Keywords: Multiple myeloma; autologous stem cell transplantation; progression; overall survival