Maintenance Use Is More Important Than the Choice of Bortezomib-Based Triplet Induction in Newly Diagnosed Multiple Myeloma Patients Undergoing Upfront Autologous Stem Cell Transplantation

Introduction: VRD (bortezomib, lenalidomide, dexamethasone) and VCD (bortezomib, cyclophosphamide, dexamethasone) are the two most commonly used triplet induction regimens in transplant eligible patients with multiple myeloma (MM). VCD is commonly used in patients with renal dysfunction at diagnosis. Given the variable results seen in head to head comparison of these (or similar) regimens to date, no definitive conclusion can be made on whether they are equivalent. This large CIBMTR registry study compares the outcomes with VRD vs. VCD induction therapy in patients undergoing upfront autologous stem cell transplant (ASCT). Methods: Patients were included if they underwent upfront ASCT for MM from January 2013 to December 2018 within 6 months of diagnosis, received VRD or VCD induction therapy and achieved at least a partial response pre-transplant. Of 1,135 patients, 914 patients received VRD and 221 received VCD therapy. Cox proportional hazards models were created for progression-free survival (PFS) and overall survival (OS). The following covariates were adjusted in the models: induction regimen (main effect), age, sex, race, performance score, hematopoietic cell transplant-comorbidity index (HCT-CI), estimated glomerular filtration rate (eGFR) at diagnosis, immunoglobulin subtype, cytogenetics, ISS stage, response status at transplant, melphalan dose, and maintenance therapy. Results: As shown in Table 1, patients in the VRD and VCD cohorts had similar age at transplant, adjusted HCT-CI scores, and distribution of high-risk cytogenetics. Patients in the VCD group were more likely to have renal impairment and ISS stage III disease. An eGFR (mL/min/1.73m2) at diagnosis < 60 was seen in 26% of VRD patients vs. 48% of VCD patients. ISS stage III was seen in 17% vs. 34% of patients, respectively. Treatment and Response: Pre-transplant response in the VRD cohort was: complete response (CR)- 17%, very good partial response (VGPR)- 48% and partial response (PR)- 35%. Response in the VCD cohort was: CR- 17%, VGPR- 42% and PR- 41%. Conditioning dose was melphalan 200 mg/m2 in 80% of patients receiving VRD vs. 69% in the VCD group. Post-transplant response was at least VGPR in 74% vs. 75% of patients, respectively. Maintenance in the VRD group was: lenalidomide based (+/- bortezomib)- 80%, bortezomib based- 5%, other-3% and none- 12% of patients. In the VCD group, maintenance was: lenalidomide based- 63%, bortezomib based- 11%, other- 1% and none- 24%. Survival: