Open-Label Study of the CDK4/6 Inhibitor SPH4336 in Subjects With Locally Advanced or Metastatic Liposarcomas

Study SPH4336-US-01 is a multicenter, non-randomized, open-label Phase 2 study of SPH4336 with a safety lead-in in subjects with CDK4-positive liposarcomas (dedifferentiated or well-differentiated/dedifferentiated liposarcomas). SPH4336 is an orally administered, molecularly targeted chemotherapy drug called a cyclin-dependent kinase inhibitor (CDK4/6 inhibitor), which acts to block the ability of cancer cells to divide and thus prevents tumors from growing. SPH4336 (tablets) will be administered orally once each day in successive 28-day cycles until demonstration of progressive disease or the development of unacceptable toxicity. The study will incorporate a safety lead-in for the initial 10 subjects. Safety will be evaluated after 10 subjects (minimum 1 cycle completed) by a Safety Review Committee (SRC). The study will be stopped if unacceptable toxicity is observed in more than 2 subjects. Tumor assessments according to RECIST v1.1 will be performed at baseline and every 6 weeks (from Cycle 1, Day 1 (C1D1)) for 36 weeks, then every 12 weeks thereafter. Plasma samples for pharmacokinetics will be collected in all subjects. Baseline (pretreatment) tumor tissue (archival or fresh) will be collected from all subjects to confirm histologically a liposarcoma with a dedifferentiated component and CDK4 positivity. Tumor tissue biomarkers (e.g., phospho-Rb, Ki-67) will be analyzed in the first 10 study subjects in baseline (pretreatment) and C1D15 tumor tissue samples.