A phase III trial of capivasertib and paclitaxel in first-line treatment of patients with metastatic triple-negative breast cancer (CAPItello290).

TPS1109 Background: Therapeutic options for patients with metastatic triple-negative breast cancer (TNBC) are limited to sequential chemotherapy, although recent advances with novel agents have been made for specific subgroups (PD-L1 inhibitor atezolizumab in combination with nab-paclitaxel in patients with PD-L1-positive tumors and PARP inhibitors in patients with germline BRCA mutations). The PI3K/AKT/PTEN signaling pathway is often activated in TNBC, mainly through activating mutations in PIK3CA or AKT1 and/or inactivating alterations in PTEN. The phase II PAKT study (NCT02423603) demonstrated that addition of the oral AKT inhibitor capivasertib to first-line paclitaxel resulted in significantly longer progression-free survival (PFS) and overall survival (OS) in patients with advanced TNBC, especially in patients with PIK3CA/AKT1/PTEN-altered tumors (Schmid et al, 2019). This phase III trial (NCT03997123) will further evaluate the efficacy and safety of capivasertib in combination with paclitaxel in first-line treatment of patients with metastatic TNBC in an unselected population and will also explore potential predictive markers of sensitivity to the combination of paclitaxel and capivasertib. Methods: Eligible patients for this double-blind, randomized, placebo-controlled trial must have metastatic TNBC or locally advanced disease not amenable to resection with curative intent. Patients must be candidates for single-agent taxane therapy and have received no prior systemic therapy for locally advanced inoperable or metastatic disease. Prior chemotherapy in the (neo)adjuvant setting must be completed ≥12 months prior to enrollment. Patients will be randomized 1:1 to paclitaxel 80 mg/m 2 (days 1, 8 and 15) with either capivasertib 400 mg twice daily or placebo (days 2–5, 9–12 and 16–19) every 28 days, until objective radiologic disease progression as defined by RECIST 1.1, unacceptable toxicity or death. Stratification factors will be prior adjuvant chemotherapy, visceral versus non-visceral disease, and geographic region. Post-randomization central testing of tumor tissue (collected prior to enrollment) will be carried out to identify predictive markers of sensitivity to treatment. The primary endpoints of this study are PFS and OS. Secondary endpoints include safety and tolerability, time to second progression or death, objective response rate, duration of response, and clinical benefit rate. Enrollment for this study started in May 2019. Clinical trial information: NCT03997123 .