Dizal reported the promising safety and pharmacokinetic data from the global Phase I study of DZD1516 in patients with HER2 positive metastatic breast cancer (HER2+ MBC) who relapsed from multiple prior treatments at the 2022 European Society for Medical Oncology Annual Meeting. Nearly 60% of patients with advanced HER2-positive breast cancer develop brain metastasis and the prognosis is extremely poor. DZD1516 is an oral, full blood-brain barrier (BBB) penetrant selective HER2 inhibitor for the treatment of HER2-positive metastatic breast cancer.

The Phase I study is enrolling HER2+ MBC patients who relapsed from or were intolerant to the standard of care (SoC). The primary objective is to evaluate the safety of DZD1516 and to define maximum tolerated dose (MTD). As of February 20, 2022, DZD1516 was explored in 22 HER2+ MBC patients from the USA and China, among whom nearly 70% had CNS metastases at baseline.

Key findings are as follows: DZD1516 was well tolerated at doses = 250 mg, and in consistent with its high selectivity, no wild-type EGFR-related AEs have been reported. Thus, 250 mg was defined as MTD. In patients, mean Kpuu,CSF was 2.1 for DZD1516 across the dose range, indicating full penetration of DZD1516 through human BBB.

18 patients had completed = 1 post treatment RECIST assessment. With a median of 7 lines of prior systemic treatment (86% treated with HER2 TKI), the best antitumor efficacy in intracranial, extracranial and overall lesions was stable disease.