[Efficacy and Safety of Ixazomib-Lenalidomide-Dexamethasone Therapy for Relapsed and Refractory Multiple Myeloma].

Ixazomib, an oral proteasome inhibitor, has been demonstrated to significantly improve progression-free survival(PFS)in patients with relapsed and refractory multiple myeloma(RRMM). Ixazomib has recently been approved in Japan, but its effectiveness and safety have not been fully investigated in a clinical setting. We retrospectively analyzed the records of 28 patients with RRMM who were treated with ixazomib in combination with lenalidomide and dexamethasone(IRd)in our institution between June 2017 and June 2018. The median patient age was 75 years at the start of IRd therapy. In total, 46.4% of the patients had previously received more than 3 treatment lines, prior to this study. The overall response rate was 37.0%, and the median PFS was 286 days. Over a median of 5 cycles of IRd, Grade 3 to 4 leukocytopenia, thrombocytopenia, and anemia occurred in 17.9%, 14.3%, and 32.1% of the patients, respectively; these incidences were higher than in previous reports. The severity of diarrhea or rash, however, was comparable with that in other studies. Patients with an estimated glomerular filtration rate of less than 50mL/min/1.73m2 received a lower cumulative dose of ixazomib and lenalidomide than those with other rates. PFS did not significantly differ between the 2 groups. Although it is necessary to carefully observe IRdtreated patients for hematological toxicity, IRd therapy is effective in heavily pretreated RRMM patients. It might be reasonable to reduce the dose of ixazomib in patients with renal impairment.