Abstract PS5-07-16: Cappa, a phase 2 study to evaluate capecitabine plus pembrolizumab as post-operative adjuvant therapy for triple-negative breast cancer with residual disease after neoadjuvant chemo-immunotherapy

Abstract The KEYNOTE-522 trial demonstrated the benefit of adding pembrolizumab to neoadjuvant chemotherapy in patients with stage II-III triple-negative breast cancer (TNBC), showing improvements in both pathological complete response (pCR) rates and overall survival. However, a key limitation of the KEYNOTE-522 trial is that it did not incorporate the use of post-neoadjuvant capecitabine for patients who did not achieve a pCR, despite evidence that capecitabine improves survival in this population. Although post-neoadjuvant capecitabine combined with pembrolizumab is commonly discussed, there is no prospective data confirming its efficacy and tolerance in clinical practice. CAPPA (NCT0597386) is a phase II, open-label, multicenter trial evaluating the addition of capecitabine to pembrolizumab as adjuvant therapy in patients with stage II-IIIb TNBC and residual disease after neoadjuvant chemo-immunotherapy. Main inclusion criteria are: (i) Histologically confirmed TNBC, defined as HER2-negative (according to ASCO/CAP criteria) and