Adjuvant Trastuzumab Plus Pertuzumab Versus Trastuzumab Alone in Patients Achieving Pathologic Complete Response After Chemotherapy With Trastuzumab and Pertuzumab: A Retrospective Cohort Study

BACKGROUND: For patients who achieve pathologic complete response (pCR) after neoadjuvant chemotherapy with trastuzumab (T) and pertuzumab (P), the benefit of adding P to T remains uncertain. We compared survival outcomes according to the type of adjuvant anti-HER2 therapy in patients with pCR after chemotherapy with TP. METHOD: Patients who achieved pCR in both the breast and axilla after neoadjuvant chemotherapy with TP were included. Recurrence-free survival (RFS) and distant recurrence-free survival (DRFS) were evaluated. Univariate and multivariate Cox proportional hazards analyses were used to assess the impact of different adjuvant therapies on RFS and DRFS. RESULTS: In total, 386 patients were included, with 69 (17.9%) receiving adjuvant TP and 317 (82.1%) receiving adjuvant T alone. At a median follow-up of 49 months, the 3-year RFS rate was 96.1%. There was no significant difference in the 3-year RFS between groups (94.2% in TP and 95.6% in T), with an adjusted hazard ratio (HR) of 1.15 (95% CI, 0.37-3.55, P = .806). In the clinical node-positive group (n = 294), there was no difference in survival between groups (HR 1.64, 95% CI, 0.58-4.65, P = .35). The multivariate analysis showed no significant predictors of recurrence or distant recurrence, including clinical tumor size, nodal status, ER/PR/HER2 status, and adjuvant radiotherapy receipt. Among 11 patients with brain metastasis after pCR, there was no difference according to the type of adjuvant anti-HER2 therapy. CONCLUSIONS: In patients with pCR who responded to chemotherapy and dual HER2 blockade (TP), the 3-year RFS and brain metastasis-free survival did not differ according to the type of adjuvant anti-HER2 therapy.