Contessa: A Multinational, Multicenter, Randomized, Phase Iii Registration Study Of Tesetaxel Plus A Reduced Dose Of Capecitabine In Patients (Pts) With Her2-, Hormone Receptor Plus (Hr Plus ) Locally Advanced Or Metastatic Breast Cancer (La/Mbc) Who Have Previously Received A Taxane.

TPS1107 Background: Chemotherapy treatments with robust efficacy that preserve quality of life are needed. Tesetaxel (T) is a novel, oral taxane that has potential advantages over currently available taxanes, including: oral administration with a low pill burden and Q3W dosing regimen; no observed hypersensitivity reactions; preclinical evidence of CNS penetration; and improved activity against chemotherapy-resistant tumors. Over 600 pts have been treated with T in clinical studies. T had robust monotherapy activity in a Phase 2 study in 38 pts with HER2-, HR+ MBC who received T Q3W, with a confirmed ORR per RECIST 1.1 of 45% and median PFS of 5.4 mo. The confirmed ORR in taxane-pretreated pts was 45%. Preclinical and clinical studies suggest that reducing the dose of capecitabine (C) in combination with a taxane may result in reduced toxicity without reduction in efficacy. Preclinical data also suggest that T may penetrate the brain at clinically relevant concentrations. CONTESSA investigates T plus a reduced dose of C as an all-oral regimen in HER2-, HR+ LA/MBC, with revised eligibility criteria to allow inclusion of pts with CNS metastases. Methods: CONTESSA is a 600-pt, multinational, multicenter, randomized (1:1), Phase 3 registration study comparing T (27 mg/m2 on Day 1 of a 21-day cycle) plus a reduced dose of C (1,650 mg/m2/day on Days 1-14 of a 21-day cycle) to the approved dose of C alone (2,500 mg/m2/day on Days 1-14 of a 21-day cycle) in pts with HER2-, HR+ LA/MBC previously treated with a taxane in the (neo)adjuvant setting. The protocol was newly amended to allow pts with known CNS metastases. The primary endpoint is PFS assessed by an Independent Radiologic Review Committee (IRC). CONTESSA is 90% powered to detect a 42% improvement in PFS (HR = 0.71). Secondary endpoints are OS, ORR, and disease control rate. Enrollment began in Dec 2017. Following review in Jan 2019, the Independent Data Monitoring Committee recommended that the Study continue as planned. Clinical trial information: NCT03326674.