A Phase 2-3, Multicenter, Randomized, Double-blind Study of Selinexor (KPT-330) Versus Placebo in Patients With Advanced Unresectable Dedifferentiated Liposarcoma (DDLS)

• Patients ≥12 years of age

• Body surface area (BSA) ≥ 1.2 m2

• Histologic evidence of DDLS at any time prior to randomization AND current evidence of DDLS requiring treatment

• Must have measurable disease per RECIST v1.1 Response Criteria

• Radiologic evidence of disease progression within 6 months prior to randomization. If the patient received other intervening therapy after documented disease progression, further disease progression must be documented after the completion of the intervening therapy

• Must have had at least two (2) prior lines of systemic therapy for liposarcoma (not to exceed 5 prior lines)

• If patient received any previous systemic therapy, the last dose must have been ≥ 21 days prior to randomization (or ≥ 5 half-lives of that drug - whichever is shorter) with all clinically significant therapy- related toxicities having resolved to less than or equal to Grade 1