BACKGROUND: I-SPY 2 is a phase 2 standing multicenter platform trial designed to screen multiple experimental regimens in combination with standard neoadjuvant chemotherapy for breast cancer. The goal is to matching experimental regimens with responding patient subtypes. We report results for veliparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, combined with carboplatin (VC). METHODS: Eligible women had ≥2.5 cm stage II/III breast cancer, categorized into 8 biomarker subtypes based on HER2, hormone-receptor status (HR) and MammaPrint. Patients are adaptively randomized within subtype to better performing regimens compared to standard therapy (control). Regimens are evaluated within 10 signatures, prospectively defined combinations of subtypes. VC plus standard therapy was considered for HER2-negative tumors and therefore evaluated in 3 signatures. The primary endpoint of I-SPY 2 is pathologic complete response (pCR). MR volume changes during treatment inform the likelihood that a patient will achieve pCR. Regimens graduate if and when they have a high (Bayesian) predictive probability of success in a subsequent phase 3 neoadjuvant trial within the graduating signature. RESULTS: VC graduated in triple-negative breast cancer with 88% predicted probability of phase 3 success. A total of 72 patients were randomized to VC and 44 to concurrent controls. Respective pCR estimates (95% probability intervals) were 51% (35%–69%) vs 26% (11%–40%). Greater toxicity of VC was manageable. CONCLUSION: The design of I-SPY 2 has the potential to efficiently identify responding tumor subtypes for the various therapies being evaluated. VC added to standard therapy improves pCR rates specifically in triple-negative breast cancer
