Characteristics and Outcomes of Autologous Hematopoietic Stem Cell Transplantation in Multiple Myeloma: A 14-Year Experience in a Limited Resource Setting

Introduction: Despite recent advances in multiple myeloma (MM) treatment, autologous transplant (HCT) remains essential for management of patients especially in areas where access to novel therapies is limited. Regional variations in treatment access and healthcare resources can affect patient outcomes. This study aims to evaluate the outcomes of MM patients undergoing HCT at King Hussein Cancer Center (KHCC) in Jordan, assessing the effectiveness of treatment in a setting with limited resources.

Methods: We performed a retrospective cohort study of MM patients who underwent HCT at KHCC between 2009 and 2023. Data were extracted from electronic medical records, including demographics, disease characteristics, treatment regimens, and clinical outcomes. Response assessments were performed according to the International Myeloma Working Group (IMWG) criteria. Key outcomes assessed were overall survival (OS) and progression-free survival (PFS). OS was defined as the time from diagnosis to death from any cause, while PFS was defined as the time from HSCT to disease progression or death. Survival analyses were conducted using the Kaplan-Meier method, and differences in survival rates were evaluated using the log-rank test.

Results: The study included 317 patients, with a median age at diagnosis of 53 years (range: 26–69 years). The cohort was predominantly male (61%). The most frequent presenting symptom was bony pain in 63% of patients. Two or more presenting symptoms were seen in 39 (12.3%) patients. At diagnosis, 76% of patients had bony lesions, and approximately 35% had fractures. About 16% of patients had more than one fracture at diagnosis, and more than half of all patients (52.1%) had more than 5 lesions at diagnosis. Almost a fourth of all patients had low albumin (<3.5g/dL), and 16% had high LDH at diagnosis. The most common light chain was Kappa (59%), and the most common heavy chain was IgG (56.2%). Cytogenetic data were available for 211 patients (66.5%). The most common International Staging System (ISS) stage was Stage III in 38% of patients. Induction regimens included bortezomib, cyclophosphamide, and dexamethasone (VCD) (17%), bortezomib, thalidomide, and dexamethasone (VTD) (37%), thalidomide and dexamethasone (TD) (13%), cyclophosphamide, thalidomide, and dexamethasone (CTD) (7%), and others (26%). Overall response to induction therapy was achieved in 73% of patients, with only 16% having lenalidomide exposure upfront. All patients received at least one HCT, with 17% undergoing more than one. The median number of pre-transplant therapy lines was one (range: 1–5).

Post-first transplant, 92% of patients achieved at least a partial response, including 13% with stringent complete response (sCR), 33% with complete response (CR), 29% with very good partial response (VGPR), and 16% with partial response (PR). In those with VGPR pre-HCT, 14 (9.7%) attained sCR, 55 (38.4%) achieved CR, 62 (43.3%) remained in VGPR. Among patients with PR pre-HCT, 11 (10%) attained sCR, 21 (19.2%) achieved CR, 25 (23%) achieved VGPR, 40 (36.7%) remained in PR. Relapse occurred in 48% of patients, with a median PFS of 31.5 months. The PFS did not differ significantly based on induction regimen or prior lenalidomide exposure. Maintenance therapy was administered to 10% of patients, with 22 receiving lenalidomide and 8 receiving thalidomide. Patients who had responses less than CR prior to HCT but achieved CR after HCT exhibited similar outcomes to those who were in CR before HCT.

For patients undergoing a second transplant, the median PFS was 22.7 months (95% CI: 14.5–30.9 months). A response to the second transplant was observed in 93% of patients, with 31 experiencing relapse. By the end of the follow-up period, 36% of patients had died. The median OS was 99 months (95% CI: 78–120 months). There was no significant variation in OS based on induction regimen, prior lenalidomide exposure and/or initial presenting symptoms.

Conclusions: While the role of HCT in the management of MM is being challenged worldwide, patients still derive significant benefits from HCT in settings with limited access to novel therapies. Overall survival rates are promising with median survival of more than 8 years for patients who underwent autologous HSCT. However, challenges such as relapse persist with limited treatment options, highlighting the need for continued advancements in treatment strategies to improve long-term outcomes.