Daiichi Sankyo has dosed the first patients in two Phase lll DESTINY-Breast03 and DESTINY-Breast02 trials investigating the safety and efficacy of [fam-] trastuzumab deruxtecan (DS-8201) to treat patients with previously treated HER2 positive unresectable and/or metastatic breast cancer.

DESTINY-Breast03 will compare [fam-] trastuzumab deruxtecan with ado-trastuzumab emtansine (T-DM1), and DESTINY-Breast02 will evaluate [fam-] trastuzumab deruxtecan in patients previously treated with standard-of-care HER2 therapies, including T-DM1.

[Fam-] trastuzumab deruxtecan is being examined by Daiichi Sankyo as a HER2 targeting antibody drug conjugate (ADC).

Daiichi Sankyo vice-president, oncology research and development DS-8201 global team leader Gilles Gallant said: “The DESTINY-Breast03 trial is a key element of our comprehensive development strategy to determine the potential of [fam-] trastuzumab deruxtecan as a second-line therapy in patients with HER2 positive metastatic breast cancer.

“DESTINY-Breast03 will also help assess whether our investigational and proprietary ADC linker and payload technology used in [fam-] trastuzumab deruxtecan demonstrates clinical relevance when compared to another HER2 targeting ADC currently approved in this setting.”

“The DESTINY-Breast03 trial is a key element of our comprehensive development strategy to determine the potential of [fam-] trastuzumab deruxtecan as a second-line therapy in patients with HER2 positive metastatic breast cancer.”

DESTINY-Breast03 is a randomised, active-controlled, open-label, multi-centre, two-arm trial that aims to enrol around 500 patients at 150 sites in North America, Asia and Europe.

The trial’s primary efficacy endpoint is progression-free survival based on blinded independent central review.

Its secondary efficacy endpoints comprise overall survival, objective response rate, duration of response, clinical benefit rate and progression-free survival based on investigator assessment.

DESTINY-Breast02 is a randomised, active-controlled, open-label, multicentre, two-arm trial that is expected to include up to 600 patients at around 160 centres in North America, South America, Europe and Asia.

The trial’s primary efficacy objective is progression-free survival based on blinded independent central review.

DESTINY-Breast02’s secondary efficacy endpoints comprise overall survival, objective response rate, duration of response, clinical benefit rate and progression-free survival.