Busulfan and thiotepa as a conditioning regimen for autologous stem cell transplantation in patients with multiple myeloma: A study of the Korean Multiple Myeloma Working Party (KMMWP-1801 study)

Busulfan, melphalan and carfilzomib high-dose chemotherapy and autologous haematopoietic stem cell transplantation in multiple myeloma

The standard of care for fit, newly diagnosed multiple myeloma patients includes induction therapy followed by consolidative high-dose chemotherapy with melphalan and autologous stem cell transplant (AHSCT). Intensified preparative regimens, such as busulfan and melphalan (BuMel), have shown promise to lengthen progression-free survival (PFS). We previously reported that the addition of bortezomib to BuMel improved PFS compared to melphalan alone in CIBMTR-matched controls. We now integrate the second-generation protease inhibitor, carfilzomib, before and after BuMel (BuMelCar) in a phase I/II trial with carfilzomib. Patients with NDMM, relapsed/refractory MM (RRMM) and those failing prior AHSCT were eligible. Primary end-points were safety and tolerability. Secondary end-points included minimal residual disease negativity rates, PFS and OS. The study enrolled 19 patients. 73% were high risk either due to R-ISS III status, adverse genetics or relapsed after prior AHSCT. The maximum tolerated dose (MTD) of carfilzomib was determined to be 36 mg/m2. Noted grade 3 toxicities were febrile neutropenia (79%), mucositis (21%) and diarrhoea (16%). The 2-year PFS for the whole cohort and MTD was 89% and 100% respectively. 80% of all patients and 82% of patients in the MTD cohort achieved MRD negativity. Further studies regarding this regimen are planned.

Busulfan plus melphalan versus high-dose melphalan as a conditioning regimen for autologous stem cell transplantation in multiple myeloma with high-risk features (KMM 2015)

Despite the development of effective agents for multiple myeloma (MM), the management of patients with high-risk MM (HRMM) is challenging. High-dose treatment followed by autologous stem cell transplantation (ASCT) is regarded as upfront treatment for transplant-eligible patients with HRMM. In the present study, we retrospectively investigated the efficacies of two conditioning regimens for upfront ASCT in newly diagnosed patients with MM and high-risk features: high-dose melphalan (HDMEL; 200 mg/m²) and busulfan plus melphalan (BUMEL). In total, 221 patients underwent ASCT between May 2005 and June 2021; among these 221 patients, 79 had high-risk cytogenetic abnormalities. In patients with high-risk cytogenetics, BUMEL showed a tendency toward longer overall survival (OS) and progression-free survival (PFS) compared to HDMEL (median OS; not reached vs. 53.2 months; P = 0.091, median PFS; not reached vs. 31.7 months; P = 0.062). Additionally, multivariate analysis revealed that BUMEL was significantly associated with PFS (hazard ratio = 0.37, 95% confidence interval = 0.15-0.89, P = 0.026). We compared BUMEL with HDMEL in patients with other high-risk features, such as high lactate dehydrogenase level, extramedullary disease, and poor response to frontline therapy. Notably, among patients with less than very good partial response (VGPR) to frontline therapy, median PFS was significantly longer in the BUMEL group than in the HDMEL group (55.1 vs. 17.3 months, respectively; P = 0.011). These findings indicate that BUMEL may be an effective conditioning regimen for upfront ASCT in MM patients with high-risk cytogenetics; BUMEL may be more appropriate than HDMEL for patients with less than VGPR to frontline therapy.

Case reports: Central nervous system involvement in patients with newly diagnosed multiple myeloma

Multiple myeloma with central nervous system involvement (CNS-MM) is rare, having a poor outcome and occurring in newly diagnosed or relapsed/refractory patients. The current report concerns 3 cases of newly diagnosed MM patients who presented with skull-derived plasmacytomas. Case 1 was a 54-year-old female patient with immunoglobulin D (IgD) subtype who developed extramedullary lesions from the sphenoid and occipital bones and the sphenoid sinus. Cases 2 and 3 had IgA subtype with left or bilateral frontal area lesions. Case 1 was treated with bortezomib, cyclophosphamide and dexamethasone (VCD) as the initial chemotherapy regimen and with bortezomib, lenalidomide, pegylated liposomal doxorubicin and dexamethasone (DVD-R) as the second line regimen. Whole-brain irradiation and intrathecal injection were given but the patient died within 9 months due to disease progression. Case 2 was treated with bortezomib, lenalidomide and dexamethasone (VRD) and received autologous hematopoietic stem cell transplantation (auto-HSCT) with a conditioning regimen of cyclophosphamide, etoposide and melphalan (CEM). Case 3 received DVD-R initially and auto-HSCT with a conditioning regimen of busulfan, cyclophosphamide, and etoposide (BuCyE). Cases 2 and 3 survived until the last follow-up more than 3 years later. Auto-HSCT with modified conditioning regimen as consolidation therapy improved the prognosis of CNS-MM.