Ixazomib for the treatment of multiple myeloma

Introduction: Proteasome inhibition is a mainstay in the treatment of multiple myeloma (MM). Bortezomib, the first proteasome inhibitor (PI) approved for MM therapy, has shown efficacy in relapsed/refractory patients and in the front-line setting. Among second-generation PIs, MLN9708 (ixazomib) is the first oral compound to be evaluated in MM treatment and has shown improvement in pharmacokinetic and pharmacodynamic parameters compared with bortezomib with a similar efficacy in the control of myeloma growth and in the prevention of bone loss. Areas covered: In this review, the authors discuss the rationale for use of PIs. They then summarize the clinical development of ixazomib in MM, from initial Phase I to Phase II studies as a monotherapy and in combination with other chemotherapeutics. Expert opinion: Preliminary data of Phase I/II trials showed that ixazomib had a good safety profile and exerted anti-myeloma activity as a single agent in relapsed/refractory patients. Furthermore, ixazomib also had efficacy in patients who were refractory to bortezomib. Its use in combination with lenalidomide and dexamethasone was shown to be an effective and welltolerated regimen in up-front treatment leading to minimal residual disease negativity in a significant number of patients. Results of Phase III trials, evaluating ixazomib in induction or maintenance therapy, are awaited.