Final Phase III Trial Results of Trastuzumab Duocarmazine in Metastatic Breast Cancer

By: Julia Fiederlein Cipriano, MS
Posted: Monday, November 27, 2023

Patients with pretreated HER2-positive locally advanced or metastatic breast cancer continued to derive a significant progression-free survival benefit from treatment with vic-trastuzumab duocarmazine vs the physician’s choice of therapy, based on the final results of the international, multicenter phase III TULIP trial. During the European Society for Medical Oncology (ESMO) Congress 2023 (Abstract 386MO), Philippe G. Aftimos, MD, of Institut Jules Bordet, Brussels, and colleagues also confirmed a trend toward a numerically prolonged duration of overall survival with this HER2-targeted antibody-drug conjugate.

The trial enrolled 437 patients who were previously treated with ado-trastuzumab emtansine or at least two HER2-targeted regimens in the metastatic setting. They were randomly assigned in a 2:1 ratio to receive 1.2 mg/kg of trastuzumab duocarmazine every 3 weeks (n = 291) or the physician’s choice of therapy (trastuzumab/capecitabine, trastuzumab/vinorelbine, trastuzumab/eribulin, or lapatinib/capecitabine; n = 146). The investigators identified progression-free survival by blinded central review as the primary endpoint. Progression-free survival by investigator review, overall survival, overall response rate, quality of life, duration of response, and safety were evaluated as key secondary endpoints.

“[In the initial analysis], preliminary overall survival data were reported,” the investigators commented. Follow-up data were provided for a median of 35.6 and 32.0 months with trastuzumab duocarmazine and the physician’s choice of therapy, respectively, at the time of this final overall survival analysis.

The median duration of overall survival was 21.0 months with trastuzumab duocarmazine and 19.5 months with the physician’s choice of therapy (hazard ratio [HR] = 0.87; P = .236). The 1-year survival estimates were 70% and 68%, respectively. Both the primary endpoint (7.0 vs 4.9 months; HR = 0.63; P = .002) and other secondary efficacy outcomes appeared to be consistent with those reported in the initial analysis. No new safety signals were documented.

Disclosure: For full disclosures of the study authors, visit cslide.ctimeetingtech.com.

ESMO Congress 2023

---