Jazz Pharmaceuticals has announced a submission to the FDA for a Biologics License Application (BLA) to seek accelerated approval for the HER2-targeted bispecific antibody zanidatamab (Zymeworks). The therapy is intended to treat unresectable, locally advanced, or metastatic HER2- positive biliary tract
cancer (BTC) among individuals who have received prior treatment, according to study authors. Image credit: | stock.adobe.com "This important milestone brings us one step closer to delivering zanidatamab, a targeted treatment option, to patients living with HER2-positive BTC, a type of cancer that is associated with a 5-year overall survival rate of less than 5%," said Rob Iannone, MD, MSCE, executive vice president, global head of research and development of Jazz Pharmaceuticals, in a press release. The study authors noted that BTC accounts for more than 1% of all adult cancers, along with gallbladder cancer and intrahepatic and extrahepatic cholangiocarcinoma—all of which are connected with a poor prognosis. The role of zanidatamab as an investigational bispecific antibody is to bind 2 non-overlapping epitopes of HER2. The process is known as biparatopic binding, according to study authors. "Zanidatamab is a biparatopic HER2-targeted bispecific antibody that simultaneously binds 2 non-overlapping epitopes of HER2 resulting in multiple mechanisms of action,” said Iannone in the press release. The study authors noted that the FDA has also previously granted zanidatamab breakthrough therapy designation among individuals with HER2 gene-amplified BTC. Additionally, 2 fast track designations were also granted as a single agent for refractory BTC and another with standard of care chemotherapy for first line gastroesophageal adenocarcinoma (GEA). Following that, the FDA granted orphan drug designations for zanidatamab to treat BTC and GEA. The submission for BLA was based on results from the Phase 2b HERIZON-BTC-01 trial that assessed zanidatamab in individuals who received prior treatment for HER2-positive BTC. The results showed that 80 HER2-postive BTC individuals enrolled in Cohort 1 of the study achieved confirmed objective response rate of 41.3%— the primary endpoint of the trial. Researchers estimated the mean progression free survival was 5.5 months among individuals. The study authors noted that historical response rates for second line standard-of-care chemotherapy with BTC was 5% to 15%. “Second-line (2L) BTC represents the first of multiple indications we are evaluating and we are excited about zanidatamab's potential as a new option for multiple HER2-expressing cancers, with ongoing Phase 3 trials in first line BTC, first line gastroesophageal adenocarcinoma (GEA), and previously treated breast cancer," said Iannone in the press release. The most reported adverse events (AEs) with zanidatamab were diarrhea and infusion-related reactions. However, the study authors noted that AEs were “low-grade, reversible and manageable prophylactically with routine supportive care,” and only occurred in 2.3% of individuals. The upcoming HERIZON-BTC-302 Phase 3 trial (NCT06282575) will evaluate zanidatamab with standard-of-care therapy, compared to chemotherapy alone, in first line advanced or metastatic HER2-positive BTC. The phase 3 study will be a confirmatory trial for zanidatamab in BTC, according to study authors.