Ricolinostat, an investigational selective HDAC6 inhibitor, appears to be safe and well tolerated among patients with relapsed or refractory multiple myeloma, according to a study published in The Lancet Oncology.1

HDAC inhibitors are a new class of agents that target multiple myeloma. Due to encouraging findings from preclinical studies that assessed ricolinostat with lenalidomide, researchers evaluated the safety and preliminary activity of ricolinostat in combination with lenalidomide and dexamethasone among patients with relapsed or refractory myeloma.

For the multicenter, phase 1b study (ClinicalTrials.gov Identified: NCT01583283), researchers enrolled 38 patients from 5 cancer centers in the United States. All participants had measurable disease, a Karnofsky Performance Status score of at least 70, adequate bone marrow reserve and hepatic function, and a creatinine clearance of 50 mL/minute or greater.

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Two dose-limiting toxicities, grade 3 syncope and grade myalgia, occurred with ricolinostat 160 mg twice daily.

The most frequently reported adverse events were fatigue, diarrhea, neutropenia, upper respiratory tract infection, anemia, and thrombocytopenia. Twenty-six percent and 18% of patients experienced grade 3 neutropenia and grade 3 fatigue, respectively.

Preliminary efficacy data show an overall response rate of 55% (95% CI, 38-71) among the 38 evaluable patients. Median progression-free survival was 20.7 months, which was similar to findings from studies investigating new agents with lenalidomide and dexamethasone.                   


  1. Yee AJ, Besinger WI, Supko JG, et al. Ricolinostat plus lenalidomide, and dexamethasone in relapsed or refractory multiple myeloma: a multicentre phase 1b trial. Lancet Oncology. 2016 Sep 16. doi: 10.1016/S1470-2045(16)30375-8 [Epub ahead of print]