Post-Transplant Maintenance Treatment Options in Multiple Myeloma

Maintenance therapy post autologous stem cell transplant (ASCT) is commonly employed in myeloma patients to prolong remission, as relapse invariably occurs after ASCT. After initial diagnosis and risk stratification, patients receive initial therapy with a combination of drugs, typically a proteasome inhibitor and an immunomodulatory imide drug (IMiD), and in those considered eligible, high-dose chemotherapy followed by autologous stem cell transplant. The aim of our study was to review the literature and consolidate evidence regarding different maintenance therapies post stem cell transplant in myeloma patients. We reviewed major databases including PubMed, Cochrane Library and Evidence-Based Medicine Reviews (EBMR), along with American Society of Hematology/American Society of Clinical Oncology (ASH/ASCO) conference abstracts to include relevant literature. Ongoing clinical trials were also reviewed. Consolidation therapy is often employed to enhance the response to induction therapy and SCT and also to delay progression. Melphalan and thalidomide with or without steroids were initially used as maintenance therapy. More recently, lenalidomide-, bortezomib-, ixazomib-, or carfilzomib-based regimens have been employed as maintenance. Lenalidomide and bortezomib are the most commonly used drugs, with the latter being preferred in high-risk populations. Newer trials are utilizing tumor-specific antigen based vaccines along with adoptive T-cell therapies, and monoclonal antibodies as maintenance therapy. We conclude that maintenance therapy post SCT, with lenalidomide or bortezomib is the standard of care in myeloma patients. Patient tolerability, disease risk stratification and prior therapy received are major determinants of the choice of maintenance. Significant toxicity associated with maintenance therapies is a hindrance to long-term maintenance post stem cell transplant.