(P 548) A PHASE 2/3 STUDY EVALUATING THE EFFICACY AND SAFETY OF UNESBULIN IN ADVANCED LEIOMYOSARCOMA (SUNRISELMS)

Objective: Leiomyosarcoma (LMS) is one of the most common and aggressive adult soft tissue sarcoma subtypes, with a high risk of recurrence and decreased disease-specific survival (George S, et al. J Clin Oncol. 2018; 36:144–150). A high unmet need remains for treatment of patients with unresectable or metastatic, relapsed or refractory LMS. In a Phase 1b study (NCT03761095), unesbulin, a microtubule polymerization inhibitor, plus dacarbazine (DTIC), was evaluated in patients with unresectable or metastatic, relapsed or refractory LMS, with acceptable benefit/risk ratio to support the start of a Phase 2/3 study. Here, we report the study design of the Phase 2/3 study SUNRISELMS that will evaluate the efficacy and safety of the combination of unesbulin with DTIC in patients with advanced LMS who have received at least one prior line of systemic therapy (NCT05269355).

Methods: SUNRISELMS is an international, randomized, double-blind, placebo-controlled, Phase 2/3 study comparing the efficacy and safety of unesbulin + DTIC versus placebo + DTIC in patients with unresectable or metastatic, relapsed or refractory LMS who received ≥ 1 prior line of systemic therapy. Patients will be randomized 2:1 to unesbulin 300 mg orally twice weekly (BIW) in each 3-week treatment cycle plus DTIC 1000 mg/m2 intravenous (IV) once every 21 days (Q21D). Matching oral placebo BIW plus DTIC IV 1000 mg/m2 will be administered Q21D. An interim analysis will be performed when ~36%, or 88 of the progression-free survival (PFS) events occur.
Eligible patients will have unresectable or metastatic, relapsed or refractory, measurable LMS according to RECIST 1.1, and be ≥18 years. Approximately 345 patients will be enrolled: 300 patients with 1 to 3 prior lines of systemic therapy for the primary analysis and 45 patients with at least 4 prior lines of systemic therapy for the exploratory interim analysis. Randomization will be stratified by histological tumor type (uterine versus nonuterine LMS), ECOG score of 0 or 1 and lines of treatment.
The primary endpoint is PFS. Key secondary endpoints include overall survival, objective response rate, disease control rate, duration of response, and safety. The study is open and recruiting patients (NCT05269355).

Results: This section does not apply to this abstract since it is a trial in progress.

Conclusion: This section does not apply to this abstract since it is a trial in progress.