Efficacy and Safety of Melphalan 140mg/m² Conditioned Autologous Stem Cell Transplantation in Elderly Pre-Dialysis and Dialysis Patients with Multiple Myeloma

Introduction:

Information is currently available for the efficacy and safety of autologous stem cell transplantation (ASCT) conditioned with melphalan in multiple myeloma patients with mild to moderate chronic kidney disease. However, little information is available on ASCT in patients with severe renal impairment or those on dialysis with multiple myeloma. This population is usually not considered for ASCT due to a high risk of mortality. One retrospective study provides data on ASCT conditioned mainly with 200mg/m² melphalan with high treatment related mortality (TRM) at 15%. Here we present safety and efficacy data on dose reduced melphalan (140/m²) conditioned ASCT in patients with severe renal impairment or haemodialysis at the time of transplant with a TRM of 0%.

Patients and methods:

We identified and report on 10 ASCT procedures carried out on 9 (7 males and 2 females) myeloma patients with a glomerular filtration rate (eGFR) of 35 ml/min/1.73m² or less between 2006 and 2016. Median age was 58(51-74) years. Five patients were on haemodialysis at diagnosis and 4 went into ASCT while on haemodialysis. Six patients had light chain multiple myeloma. Initial therapy was bortezomib based in 6 patients, with 4 receiving thalidomide and 1 received both thalidomide and bortezomib pre ASCT. Most patients were mobilised with G-CSF alone and only 1 received cyclophosphamide and G-CSF. ASCT was conditioned in all cases with 140mg/m²of Melphalan. Patients on hemofiltration were supported during ASCT as per institutional guidelines. We collected data on response, stem cell collection, engraftment, progression free survival (PFS), overall survival (OS) and treatment related mortality (TRM).

Results:

Median follow up for the whole group was 24 (6-114) months. Pre ASCT 6 patients were in VGPR and 3 in PR. The median cell dose collected was 6.92×10 ⁶ CD34 cells/kg (range 3.06-8.27). The median time to neutrophil engraftment (absolute neutrophil count>0.5×10⁹/L) and platelet engraftment (>20×10⁹/L) was at day 13 and 15 respectively. The TRM at day+100 was 0%. Post ASCT best responses were as follows-7 patients were in VGPR; 1 in PR and 1 progressed. The median PFS was 24months and median OS was 27 months. At the time of data collection only one person had died. The cause of death was disease progression with refractory disease. One patient became free of haemodialysis pre ASCT, one after ASCT and 1 more dropped frequency of dialysis sessions from 3 to 2 per week.

Discussion:

Autologous stem cell transplant using low dose Melphalan (140mg/m²) as consolidation post a bortezomib based induction therapy is an effective and safe treatment option for the pre-dialysis and dialysis patients with multiple myeloma. In our hands the TRM is extremely low suggesting the lower dose to be more appropriate than melphalan at 200mg/m². It provides good PFS and in some cases freedom from haemodialysis. Further prospective trials are needed to confirm these findings.