Selinexor Treatment of Refractory Myeloma

A Phase 2b, Open-Label, Single-Arm Study of Selinexor (KPT-330) Plus Low-Dose Dexamethasone (Sd) in Patients With Multiple Myeloma Previously Treated With Lenalidomide, Pomalidomide, Bortezomib, Carfilzomib, and an Anti-CD38 Monoclonal Antibody (mAb) Daratumumab, and Refractory to Prior Treatment With Glucocorticoids, an Immunomodulatory Agent, a Proteasome Inhibitor, and an the Anti-CD38 mAb Daratumumab

This is a Phase 2b, single-arm, open-label, multicenter study of selinexor 80 mg plus dexamethasone 20 mg (Sd) dosed twice weekly in four-week cycles, in patients with penta-refractory MM (Parts 1 and 2) or quad refractory MM (Part 1 only).

This is a Phase 2b, single-arm, open-label, multicenter study of selinexor 80 mg plus dexamethasone 20 mg (Sd), both dosed twice weekly in each four-week cycle, in patients with MM previously treated with lenalidomide, pomalidomide, bortezomib, carfilzomib, and daratumumab and refractory to prior treatment with glucocorticoids, an immunomodulatory agent (IMiD), a proteasome inhibitor (PI), and daratumumab.

This study consists of two parts:

• Part 1 enrolled patients with both quad-refractory MM and penta-refractory MM.
• Part 2 will enroll patients with penta-refractory MM only.

Inclusion Criteria:

Measurable MM based on modified IMWG guidelines. Defined by at least one of the following:

1. Serum M-protein ≥ 0.5 g/dL by serum electrophoresis (SPEP) or for IgA myeloma, by quantitative IgA

2. Urinary M-protein excretion ≥ 200 mg/24 hours

3. Free Light Chain (FLC) ≥ 100 mg/L, provided that the FLC ratio is abnormal

4. If serum protein electrophoresis is felt to be unreliable for routine M-protein measurement, then quantitative Ig levels by nephelometry or turbidimetry are acceptable

   • Must have previously received ≥ 3 anti-MM regimens including: an alkylating agent, lenalidomide, pomalidomide, bortezomib, carfilzomib, daratumumab, and a glucocorticoid. There is no upper limit on the number of prior therapies provided that all other inclusion/exclusion criteria are met.
   • MM refractory to previous treatment with one or more glucocorticoids, parenteral PI (i.e., bortezomib and/or carfilzomib), IMiD (i.e., lenalidomide and/or pomalidomide), and the anti-CD38 mAb, daratumumab. Refractory is defined as ≤ 25% response to therapy, or progression during therapy or progression within 60 days after completion of therapy.

Exclusion Criteria:

• Active smoldering MM.
• Active plasma cell leukemia.
• Documented systemic amyloid light chain amyloidosis.
• Active CNS MM.