Treatment patterns and clinical outcomes in patients with triple-negative breast cancer (TNBC) and residual disease (RD) after neoadjuvant chemoimmunotherapy.

Abstract

e12678 Background: Evidence on the treatment and prognosis of patients with TNBC and RD after neoadjuvant chemoimmunotherapy remains limited. Methods: We conducted a single-center cohort study to analyze treatment patterns and clinical outcomes of patients with TNBC and RD after neoadjuvant chemoimmunotherapy who were discussed at the multidisciplinary tumor board of the European Institute of Oncology (Milan) from Jul 2022 to Aug 2025. Endpoints included disease-free survival (DFS) and overall survival (OS), calculated from surgery (study baseline). Results: A total of 134 patients were included. The median age at baseline was 49 years (IQR: 41-57) and 13% carried a germline BRCA pathogenic variant. 19% of patients did not complete the neoadjuvant phase of the KEYNOTE-522 regimen due to toxicity, comorbidity and/or disease progression. Post-neoadjuvant treatments included: pembrolizumab alone (33%), capecitabine plus pembrolizumab (26%), capecitabine alone (16%), olaparib with or without pembrolizumab (6%), an anti-Trop2 antibody-drug conjugate (ADC) (4%), anthracycline-based chemotherapy (4%), other treatment (1%), or no further systemic therapy (8%). At a median follow-up of 20.7 months, 68 DFS events (78% within 1 year after surgery) and 20 deaths were reported. The median DFS was 15.3 months (95%CI: 9.6-21.0); the 2y-DFS and OS rates were 41% and 81%, respectively. Among patients who developed distant recurrence (n = 62), 6 were lost to follow-up after recurrence, and 95% of the remaining received at least one cycle of first-line therapy for metastatic disease (attrition: 5%). Conclusions: Residual disease after neoadjuvant chemoimmunotherapy was associated with a 60% probability of recurrence at 2 years. Postneoadjuvant management was highly heterogeneous, underscoring the need for improved treatment strategies, including ADCs and non-cross-resistant immunotherapy approaches, in this setting.