Ruxolitinib overcame lenalidomide resistance in myeloma

CHICAGO – The JAK 1/2 inhibitor ruxolitinib (Jakafi), in combination with lenalidomide and methylprednisolone, overcame resistance to lenalidomide in about half of 28 heavily pre-treated patients with relapsed/refractory multiple myeloma, based on phase I trial results presented at the annual meeting of the American Society of Clinical Oncology (ASCO).

The clinical trial is the first to demonstrate the activity of a JAK inhibitor in the treatment of myeloma patients, according to investigator James R. Berenson, MD, medical and scientific director for the Institute for Myeloma & Bone Cancer Research (IMBCR), West Hollywood, Calif.

^{Andrew Bowser/MDedge News}

Dr. James R. Berenson

“These promising results have led to the expansion of the current clinical trial and provide the basis for exploration of this and other JAK inhibitor-containing combinations for treating patients with myeloma and other malignant diseases,” he added.

The dose-escalation study enrolled 28 patients with relapsed/refractory multiple myeloma who had previous treatment with lenalidomide/steroids and a proteasome inhibitor. Subjects received ruxolitinib twice daily continuously, lenalidomide daily on days 1-21 of a 28-day cycle, and methylprednisolone orally every other day. A traditional 3+3 dose escalation design was used to enroll subjects in four cohorts. In DL0, patients received ruxolitinib 5 mg, lenalidomide 5 mg, and methylprednisolone 40 mg. In DL+1 and +2, both doses of lenalidomide and methylprednisolone remained unchanged, and ruxolitinib was escalated to 10 and 15 mg, respectively. In DL+3, lenalidomide was escalated to 10 mg with methylprednisolone unchanged and ruxolitinib at 15 mg. A total of 19 patients were treated at the highest dose level, which was ruxolitinib 15 mg twice daily on days 1-28, lenalidomide 10 mg daily on days 1-21, and methylprednisolone 40 mg every other day.

The overall response rate was 39% (10 of 26 evaluable patients), Dr. Berenson reported. The clinical benefit rate was 50% (13 of 26 patients), with a median duration of response of 5.6 months in that group.

There were no dose-limiting toxicities. Grade 3 toxicities reported included thrombocytopenia in 11% (3 patients, gastrointestinal bleeding in 11% (3 patients), and anemia in 7% (2 patients).