Abstract PD7-07: Three-year event-free survival from a phase 2 study of peri-operative immune checkpoint inhibition and cryoablation in women with hormone receptor-negative, HER2-negative early stage/resectable breast cancer (ipilimumab/nivolumab cohort)

Abstract Background: Triple-negative breast cancer (TNBC) is an aggressive subtype associated with a high risk of early recurrence. Patients who do not achieve a pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) have a 3-year event-free survival (EFS) of less than 60%. Preclinical and early clinical data suggest that immune checkpoint inhibition (ICI) and cryoablation (cryo) may synergize to enhance antitumor immunity. We conducted a single-arm, phase 2 study evaluating peri-operative ICI and cryo in patients with early-stage, resectable TNBC. In the initial cohort, ipilimumab (ipi) plus nivolumab (nivo) were administered. After the United States FDA approval of pembrolizumab as standard of care (SOC) for high-risk, early-stage TNBC in 2021, the study was modified to allow for SOC ICI. The pembrolizumab cohort is not yet mature for analysis. Here, we report 3-year EFS for the ipi/nivo cohort. Methods: In this prospective, single-arm, multicenter, phase 2 trial, patients aged ≥18 years with early-stage, resectable, hormone receptor-negative (ER