Abstract PS4-08-14: A Systematic Review and Extracted Individual Patient Data Meta-analysis of Long- Term Outcomes in Triple-Negative Breast Cancer after a Pathologic Complete Response: Does the Type of Neoadjuvant Therapy Matter?

Abstract INTRODUCTION: Neoadjuvant chemotherapy is standard of care for stage IB-III triple-negative breast cancer (TNBC), with pathological complete response (pCR) strongly associated with survival. Although the escalation of neoadjuvant therapies with platinum and immune checkpoint inhibitors (ICI) improves pCR rates and long-term outcomes, patients with pCR in the control arms of pivotal trials also show favorable outcomes. Whether the type of neoadjuvant regimen leading to pCR impacts long-term survival differently is largely unknown. Methods: We conducted a systematic review and meta-analysis, searching PubMed, Embase, Cochrane, and conference proceedings for phase II and III trials including patients with early-stage TNBC and pCR. A pooled analysis of Kaplan-Meier-derived individual patient data was performed for event-free survival (EFS) and overall survival (OS), with subgroup analyses by treatment regimens. Results: Of 2,830 identified publications, 18 trials (16 randomized and 2 single-arm) comprising 3,430 TNBC patients with pCR were included. Neoadjuvant ICI with chemotherapy improved EFS (HR 0.67; 95%CI 0.50-0.89; p