Long-term outcomes in triple-negative breast cancer after a pathologic complete response: does the type of...

Neoadjuvant chemotherapy is standard for stage IB-III triple-negative breast cancer (TNBC), with pathological complete response (pCR) strongly associated with survival. Although escalation with platinum and immune checkpoint inhibitors (ICI) improves pCR and long-term outcomes, patients with pCR in control arms of pivotal trials also show favorable outcomes. Whether the regimen leading to pCR impacts long-term survival is largely unknown.

We conducted a systematic review and meta-analysis, searching phase II and III trials including early-stage TNBC patients with 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.

Of 2830 identified publications, 18 trials comprising 3430 patients were included. Neoadjuvant ICI with chemotherapy improved EFS (HR 0.67; 95%CI 0.50-0.89; p < 0.01) compared with chemotherapy-only regimens, with no significant OS difference (HR 0.84; 95%CI 0.50-1.41; P = 0.51). In contrast, EFS and OS were not significantly different regardless of platinum use (HR 0.55; 95%CI 0.20-1.50; P = 0.24 and HR 0.33; 95%CI 0.09-1.22; P = 0.10, respectively). Similarly, anthracycline-containing regimens showed comparable EFS to anthracycline-free regimens (HR 0.86; 95%CI 0.51-1.45; P = 0.58). For patients with pCR after ICI therapy, no benefit of adjuvant ICI for EFS or OS was observed (HR 1.16; 95%CI 0.55-2.44; P = 0.70 and HR 2.91; 95%CI 0.40-21.37; P = 0.29, respectively).

These findings suggest that the context in which a pCR is achieved may influence long-term outcomes. Neoadjuvant ICI-based regimens improve EFS in patients with early-stage TNBC and pCR. However, EFS seems not to be impacted by neoadjuvant chemotherapy type.