Sonrotoclax (BGB-11417) in Combination with Dexamethasone for the Treatment of Relapsed/Refractory Multiple Myeloma with t(11;14): Safety, Efficacy, and Determination of Recommended Phase 2 Dose
As of May 26, 2023, 19 patients have been enrolled in the 80-, 160-, and 320-mg (n=3 each) and 640-mg (n=10 patients) dose-escalation cohorts. The median age was 68 years (range, 52-81 years). The median prior lines of therapy was 4 (range, 1-12) and 11 patients (58%) failed on a prior anti-CD38 antibody. The most common AEs (>20% of all patients) were insomnia (n=9; 47%), fatigue (n=6; 32%), nausea (n=5; 26%), and arthralgia (n=4; 21%); none of which were severity grade ≥3. Three patients (16%) experienced grade ≥3 treatment-emergent AEs (TEAEs). One patient (33%) in the 160-mg cohort had grade 3 increases in liver enzymes and diarrhea; one patient (10%) in the 640-mg cohort had a grade 3 decrease lymphocyte count and hypokalemia; and one patient (10%) in the 640-mg cohort had grade 3 cataracts and retinal detachment. Three patients experienced COVID-19 (grade 1-2, n=2; grade ≥3, n=1). Three patients experienced TEAEs that led to treatment discontinuation (COVID-19, cancer pain, hematuria; n=1 each). No patient, across all dose levels tested, experienced a DLTs; thus, sonrotoclax 640 mg daily was the determined to be the MAD and the RP2D in combination with dexamethasone.
Four patients (21%) died while on study; however, no deaths were determined by the investigators to be associated with study treatment. One patient died from COVID-19 while receiving study therapy; three additional patients died ≥50 days after treatment discontinuation (COVID, progressive disease, and unknown causes, n=1 each).
With a median treatment duration of 120 days (range, 30-526), ORR was 58%; 11 patients had a PR or better (n=6, PR; n=2, very good PR; n=2, CR; n=1, stringent CR [sCR]; Figure). The ORR for the 640-mg cohort was 70% (n=3, PR; n=2 VGPR; n=1, CR; n=1, sCR). Nine patients remained on treatment; the longest duration of response was 483 days (20 cycles) which, at data cutoff, was still ongoing.