Safety and Effectiveness of Adriamycin and Cyclophosphamide Followed by Dose Dense (Every 2 Weeks) Paclitaxel Given With Trastuzumab as Neoadjuvant Treatment in HER2-Positive Early-Stage Breast Cancer.

Background: Traditionally, in neoadjuvant anthracycline-based chemotherapy for early-stage HER2+ breast cancer, paclitaxel is administered weekly for 12 doses combined with trastuzumab every 3 weeks (ACTH-W). In Ontario Canada, an alternative protocol consists of administering paclitaxel every 2 weeks concurrently with trastuzumab every 2 weeks for 4 doses (ACTH-O).

Methods: We conducted a retrospective, single-institution chart review of sequential patients treated between 2014 and 2023 to evaluate the efficacy, safety, and resource utilization of ACTH-O compared with FEC-DH, TCH, and ACTH-W.

Results: A total of 300 patients were included in this analysis. There was no statistically significant difference in pCR rates between ACTH-O (37.1%), FEC-DH (33.6%), and TCH (48.0%). Although the odds of achieving pCR was higher with ACTH-W than ACTH-O, disease-free survival at 3 years did not differ between any of the regimens (93.4% for ACTH-O, 90% for ACTH-W, 87.9% for 93.3 FEC-DH). Discontinuation was less frequent with ACTH-O, with similar rare cardiotoxicity events across all regimens. The minimum number of planned healthcare in-person visits for ACTH-O was half that of ACTH-W. The estimated cost of treatment administration was reduced by approximately one third, an important consideration in a resource-constrained healthcare system.

Conclusion: ACTH-O regimen is a viable alternative to standard anthracycline-based regimens in HER2+ early breast cancer. It offers similar long-term outcomes while reducing time toxicity and healthcare costs. Given these advantages, ACTH-O warrants consideration for broader clinical adoption.