Recent Updates on Multiple Myeloma

Abstract

extra-hematological toxicity, and the brief period of neutropenia [24, 25]. Outpatient HSCT has certain inclusion criteria and exclusion criteria as well as several advantages that include: significant reduction in costs; saving hospital beds; lower rate of infections; and lower morbidity and treatment-related mortality [24,[26][27][28].In patients with MM, maintenance therapy after autologous HSCT has been shown to deepen and prolong responses and increase OS and progression-free survival (PFS) [29]. Lenalidomide maintenance given after autologous HSCT till disease progression is the standard of care in patients with SR MM while bortezomib maintenance therapy after autologous HSCT is preferable in MM patients having: HR cytogenetics, renal insufficiency, inability to tolerate lenalidomide, and previous history of another cancer [30][31][32]. Continuous therapy has been shown to significantly improve OS and PFS [33, 34]. Continuous therapy till disease progression has become a key strategy in the treatment of patients with MM as it has been shown to improve duration of remission and it represents the standard approach for patients with MM both at diagnosis and at relapse [35, 36].Unfortunately, nearly all MM patients ultimately relapse, even those who experience a complete response (CR) to initial therapy [19]. Management of the relapsed disease remains a critical aspect of MM care and an important area of ongoing research [19]. New treatment strategies and therapeutic modalities are needed to treat MM in relapse, particularly in case of triple-refractory disease [1]. Treatment of relapsed MM should depend on: the number of relapses encountered; the previous anti-myeloma treatment; the presence of de novo or acquired drug resistance; aggressiveness of disease relapse particularly in case of extramedullary disease, plasma cell leukemia, or clonal evolution [3, 37].Minimal residual disease (MRD) is an important factor that can independently predict the prognosis of MM during treatment as undetectable MRD has been shown to improve PFS and OS regardless: disease status, prior transplant, or cytogenetic risk [38]. Flow cytometry has become a valuable tool to monitor MRD and evaluate the depth of CR. However, next-generation flow cytometry is more sensitive than the standard flow cytometry in detecting MRD in patients with MM [39]. Finally, the development of novel targeting therapies with different mechanisms of action is needed to achieve deep and durable responses in an attempt to cure MM while identification of tumor intrinsic and extrinsic resistance mechanisms may direct the design of combinations of novel drugs that prevent or overcome drug resistance so as to improve patient survival [40, 41].