Objective:

To compare the effectiveness, safety, and tolerability of adjuvant trastuzumab plus pertuzumab (HP) versus trastuzumab emtansine (T-DM1) in patients with HER2-positive breast cancer with residual invasive disease after neoadjuvant therapy.

Approach:

• Study Design: A single-center, retrospective, observational study was conducted, including patients with HER2-positive breast cancer who underwent surgery following neoadjuvant therapy.
• Patient Selection: Patients were enrolled between 2020 and 2024, with propensity score matching applied to adjust for baseline differences.
• Analysis Methods: Kaplan-Meier survival analysis and Cox proportional hazards models were used to compare survival outcomes and adverse events.

Key Findings:

• 272 patients were analyzed, with 134 remaining after propensity score matching.
• No statistically significant differences in short-term survival outcomes were detected between the HP and T-DM1 groups.
• Grade 3 or higher adverse events occurred more frequently in the T-DM1 group, particularly thrombocytopenia.
• Treatment interruption or regimen modification occurred in 22.7% of T-DM1 patients compared to 2.2% in the HP group.

Interpretation:

In HER2-positive breast cancer patients with residual invasive disease after neoadjuvant therapy, adjuvant HP demonstrated a more favorable safety and tolerability profile compared to T-DM1.

Limitations:

• The study is retrospective and conducted at a single center, which may limit generalizability.
• The follow-up period of 37.7 months may not capture long-term outcomes.

Conclusion:

No statistically significant difference in short-term recurrence or survival outcomes was detected between adjuvant HP and T-DM1, while HP was associated with a more favorable safety and tolerability profile.