Selinexor and Backbone Treatments of Multiple Myeloma Patients

This is a multi-center, open-label, clinical study with Dose Escalation (Phase 1) and Expansion (Phase 2) to independently assess the MTD, efficacy , and safety of 11 combination therapies in 12 arms in patients with RRMM and NDMM. Patients will be assigned to treatment arms based on their diagnoses and treatment histories. For 9 patients, a PK Run-in period will precede Cycle 1 (DLT evaluation) to assess selinexor PK when co-administered with a strong CYP3A4 inhibitor. In the Dose Escalation Phase (Phase 1): (a) in Arm 1 (SPd), Arm 2 (SVd), and Arm 3 (SRd in RRMM), patients will be randomized to either QW or BIW selinexor dosing cohorts; (b) in Arm 5 (SDd), patients will be sequentially assigned in blocks of 3 to either QW or BIW selinexor dosing; (c) in Arm 4 (SPVd), Arm 6 (SKd), Arm 7 (Srd in NDMM), Arm 8 (SNd), Arm 9 (SPEd), Arm 10 (SBd), Arm 11 (SDPd), and Arm 12 (SMd) patients will be assigned to QW selinexor dosing. Cohort 1.4 is included from Version 10 to study safety and tolerability of SPd with selinexor 40 mg QW, is lower than RP2D (ie, selinexor 60 mg QW) in combination with pomalidomide 4 mg. Cohort 1.4 is a different expansion cohort from the one with RP2D (ie, Cohort 1.3). In Cohort 1.4, 20 patients will be enrolled in total. Starting in protocol Version 8.0, patients enrolled to the Dose Escalation Phase of Arm 4 (SPVd), Arm 6 (SKd), Arm 8 (SNd), Arm 9 (SPEd), Arm 10 (SBd), and Arm 11 (SDPd) will first be enrolled to a 14-day PK Run-in period (selinexor +/- clarithromycin) until 9 patients have been enrolled. During this 14-day PK Run-in period, selinexor 40 milligrams (mg) will be administered alone on Day 1, clarithromycin 500 mg twice daily (BID) will be administered on Days 2-8, and selinexor 40 mg will again be administered on Day 8 with the morning clarithromycin dose. Blood samples for PK analysis will be collected pre-dose and 1 (± 10 min), 1.5 (± 10 min), 2 (± 10 min), 3 (± 10 min), 4 (± 10 min), 5 (± 10 min), 6 (± 10 min), 8 (± 10 min), and 24 h (± 30 min) hours after selinexor is dosed on Day 1 (without clarithromycin) and Day 8 (with clarithromycin). Patients will then proceed to the DLT evaluation period that will begin after the completion of the 14-day PK Run-in period; this day will be designated as Cycle 1 Day 1 (C1D1) in the Dose Escalation Phase. Starting in protocol v12, in Arm 12 (SMd) additional PK sampling for mezigdomide will be collected concurrently with selinexor on Cycle 1 Day 1 (C1D1) at 2,4, and 6 hrs post-mezigdomide/selinexor dose; additional mezigdomide PK samples will be collected pre-mezigdomide dose on Days 8 and 15 of Cycles 1 and 2.