BOSTON – The all-oral combination of selinexor, lenalidomide, and dexamethasone has demonstrated efficacy in patients with relapsed/refractory multiple myeloma, particularly those who are lenalidomide naive.
In the phase 1/2 STOMP trial (), selinexor plus lenalidomide and dexamethasone produced an overall response rate (ORR) of 60% in all evaluable patients and an ORR of 92% in lenalidomide-naive patients.
, of Dalhousie University in Halifax, N.S., presented these results at the International Myeloma Workshop held by the International Myeloma Society.
Dr. White discussed results in myeloma patients who had received at least one prior line of therapy. This arm of the STOMP trial has enrolled 24 patients. Their median age at baseline was 67 years (range, 49-84 years), and their median time from diagnosis was 4.5 years (range, less than 1-22 years).
The patients had received a median of 1 (range, 1-8) prior therapies. Half of patients had received a transplant. All patients had received a proteasome inhibitor (65% refractory), and 38% had received prior lenalidomide (21% refractory).
Patients received selinexor at 60 mg once or twice weekly or at 80 mg once weekly on a 28-day cycle. They received dexamethasone at 20 mg twice weekly or 40 mg once weekly and lenalidomide at 25 mg once daily every 21 days.
The recommended phase 2 dosing schedule was selinexor at 60 mg once weekly plus lenalidomide at 25 mg daily and dexamethasone at 40 mg once weekly. Half of patients (n = 12) received this dosing schedule.
There were no dose-limiting toxicities (DLTs) at the recommended phase 2 dose. When selinexor was given at 60 mg twice weekly, DLTs included grade 3 fatigue, grade 3 anorexia and weight loss, and grade 4 thrombocytopenia (n = 2). When selinexor was given at 80 mg once weekly, the DLTs were grade 4 thrombocytopenia (n = 2).
“The side-effect profile was as expected, with mainly grade 3/4 toxicity being hematologic and primarily thrombocytopenia and neutropenia,” Dr. White said. “Frequent gastrointestinal side effects [were] expected. Investigators were able to manage that with appropriate supportive care and antiemetics in particular.”
Among patients who received the recommended phase 2 dose, the grade 4 treatment-related adverse events (AEs) were thrombocytopenia (n = 4) and neutropenia (n = 4). Grade 3 treatment-related AEs were thrombocytopenia (n = 3), neutropenia (n = 4), anemia (n = 1), nausea (n = 1), asthenia (n = 1), fatigue (n = 2), and dehydration (n = 1). Common grade 1/2 treatment-related AEs in patients who received the recommended phase 2 dose were nausea (n = 6), anorexia (n = 5), weight loss (n = 5), vomiting (n = 4), diarrhea (n = 4), and fatigue (n = 4).