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Purpose:To evaluate sitravatinib, an inhibitor of multiple receptor tyrosine kinases (RTK), for the treatment of well-differentiated/dedifferentiated liposarcoma (WD/DD LPS).Patients and Methods:This multicenter, open-label, Phase II trial enrolled patients with advanced WD/DD LPS who had received at least one prior systemic regimen and had progression within 12 weeks of enrollment. Patients received sitravatinib 150 mg (later amended to 120 mg) orally daily. A Simon two-stage design was used to evaluate for an improvement in the primary endpoint, progression-free rate at 12 weeks (PFR12), from 20% to 40%. Secondary endpoints included antitumor activity and safety. A subset of patients underwent paired biopsies analyzed using reverse-phase protein array.Results:Twenty-nine patients enrolled. Median age was 62 years and 31% had received 3 or more prior lines. Most patients (93%) had DDLPS or mixed WD/DD LPS. Overall, 12 of 29 patients (41%) were alive and progression-free at 12 weeks and the study met the primary endpoint. There were no confirmed responses. Median progression-free survival was 11.7 weeks [95% confidence interval (CI): 5.9–35.9] and median overall survival was 31.7 weeks (95% CI: 18.1–90.1). The most common treatment-related adverse events were diarrhea (59%), hypertension (52%), hoarseness (41%), mucositis (31%), and nausea (31%). Baseline expression of phospho-RTKs was not significantly different between patients with and without clinical benefit from sitravatinib, but the number of samples was small.Conclusions:Sitravatinib provided a PFR12 of 41% and meaningful disease control in a subset of patients with advanced, progressive WD/DD LPS.

Purpose: This phase I study assessed the safety, pharmacokinetics (PKs), and efficacy of MIW815 (ADU-S100), a novel synthetic cyclic dinucleotide that activates the stimulator of IFN genes (STING) pathway, in patients with advanced/metastatic cancers. Patients and Methods: Patients (n = 47) received weekly i.t. injections of MIW815, 50 to 6,400 μg, on a 3-weeks-on/1-week-off schedule. Results: A maximum tolerated dose was not reached. Most common treatment-related adverse events were pyrexia (17%), chills, and injection-site pain (each 15%). MIW815 was rapidly absorbed from the injection site with dose-proportional PK, a rapid terminal plasma half-life (approximately 24 minutes), and high interindividual variability. One patient had a partial response (PR; Merkel cell carcinoma); two patients had unconfirmed PR (parotid cancer, myxofibrosarcoma). Lesion size was stable or decreased in 94% of evaluable, injected lesions. RNA expression and immune infiltration assessments in paired tumor biopsies did not reveal significant on-treatment changes. However, increases in inflammatory cytokines and peripheral blood T-cell clonal expansion suggested systemic immune activation. Conclusions: MIW815 was well tolerated in patients with advanced/metastatic cancers. Clinical activity of single-agent MIW815 was limited in this first-in-human study; however, evidence of systemic immune activation was seen.