Trastuzumab emtansine versus trastuzumab plus pertuzumab for HER2-positive breast cancer with residual disease after neoadjuvant therapy: a real-world study.

OBJECTIVE

To evaluate the efficacy and safety of T-DM1 versus trastuzumab plus pertuzumab in adjuvant treatment of HER2-positive breast cancer patients with residual invasive disease after neoadjuvant therapy.

METHODS

This study retrospectively analyzed 184 patients treated at Renmin Hospital of Wuhan University from January 2019 to January 2022. The patients were divided into a T-DM1 treatment group and a dual-target treatment group based on whether they received T-DM1 or trastuzumab plus pertuzumab during adjuvant therapy. Clinical and pathological data of the two groups were collected before and after surgery, and follow-up was conducted. The primary study endpoint was disease-free survival (DFS).

RESULTS

Disease progression occurred in 20.3% of the dual-target treatment group and 12.6% of the T-DM1 treatment group. Although T-DM1 was associated with a 38% reduction in recurrence risk, the difference was not statistically significant (HR: 0.62, 95% CI: 0.30-1.26, P = 0.19). Exploratory subgroup analyses suggested improved DFS with T-DM1 in patients with initially unresectable disease, preoperative lymph node positivity, or poor pathological response (MP 1-3 or RCB III); In terms of safety, both groups of patients were consistent with the known safety profile. No treatment-related deaths occurred. Grade ≥3 thrombocytopenia was significantly more frequent with T-DM1 (8.45% vs 0.88%, P = 0.01), representing a clinically important toxicity trade-off.

CONCLUSION

The use of T-DM1 in the adjuvant setting suggests improved disease-free survival in HER2-positive non-pCR patients who were initially inoperable, had preoperative lymph node positivity, or exhibited poor pathological response (MP grade 1-3 or RCB III).