A Cohort Study of the Effectiveness of Trastuzumab Deruxtecan for Treating Metastatic Progressive HER2-Positive Breast Cancer.

Authors

• Ameer Basta
• Kyle Lien, Lehigh Valley Health NetworkFollow
• Gabris Ni
• Weihong Sun
• Junmin Whiting
• Melissa Armitage
• Aixa E Soyano
• Avan Armaghani
• Loretta Loftus
• Tracey O'Connor
• Kathrin Dvir
• Hyo S Han
• Hatem Soliman
• Brian J Czerniecki
• Ricardo L B Costa

Publication/Presentation Date

6-16-2026

Abstract

INTRODUCTION: The FDA approved trastuzumab deruxtecan (T-DXd) for treating human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (mBC) based on the phase II trial DESTINY-Breast01. The phase III trial DESTINY-Breast03 confirmed the efficacy of T-DXd with improvements in progression-free survival (PFS) (HR = 0.33) and overall survival (OS) (HR = 0.64) compared with trastuzumab emtansine (T-DM1).

PATIENTS AND METHODS: This is a retrospective, single-institution, effectiveness study of patients with HER2+ mBC treated with T-DXd. Data were summarized on de-identified patients, tumors, and outcomes per treating physician. The Kaplan-Meier method was used for survival analyses. A 2-sided P value < .05 was considered statistically significant. Cox proportional hazards models were utilized. The initial model included all variables, and backward elimination was used to remove variables with P > .1 to obtain the final model.

RESULTS: Eighty-four patients with progressive HER2+ mBC with a median age of 57 years (27-78 years) were treated with T-DXd. Of the total patients, 16.7% had an ECOG Performance Status ≥2, and 69.0% had 1 or 2 prior lines of therapy for mBC. Almost half (45.2%) had received prior T-DM1, and only 69.0% started T-DXd at full dose. Median real-world PFS (rwPFS) was 13.3 months (95% CI, 11.4-16.9). No significant differences in rwPFS were observed in stratified analyses. Median real-world OS (rwOS) was 38.7 months (95% CI, 24.5-61.8).

CONCLUSION: T-DXd showed effectiveness for treating HER2+ mBC in a real-world cohort with pretreated patients.

Volume

26

Issue

8

First Page

7

Last Page

13

ISSN

1938-0666

Published In/Presented At

Basta, A., Lien, K., Ni, G., Sun, W., Whiting, J., Armitage, M., Soyano, A. E., Armaghani, A., Loftus, L., O'Connor, T., Dvir, K., Han, H. S., Soliman, H., Czerniecki, B. J., & Costa, R. L. B. (2026). A Cohort Study of the Effectiveness of Trastuzumab Deruxtecan for Treating Metastatic Progressive HER2-Positive Breast Cancer. Clinical breast cancer, 26(8), 7–13. Advance online publication. https://doi.org/10.1016/j.clbc.2026.06.003

Disciplines

Medical Education | Medicine and Health Sciences

PubMedID

42418955

Department(s)

USF-LVHN SELECT Program, USF-LVHN SELECT Program Students

Document Type

Article