Partner Therapeutics, Inc. has announced that the US Food and Drug Administration has granted Orphan Drug Designation to zenocutuzumab-zbco for the treatment of adults with advanced unresectable or metastatic cholangiocarcinoma.
The designation supports the continued development of the therapy under the company’s BIZENGRI® programme for rare cancers.
Zenocutuzumab-zbco is being developed for a molecularly defined subset of cholangiocarcinoma patients whose tumours harbour neuregulin 1 (NRG1) gene fusions. Cholangiocarcinoma is a rare and aggressive cancer of the bile ducts that is often diagnosed at an advanced stage, when curative treatment options are limited. Around 8,000 new cases are reported annually in the United States, and the overall five-year survival rate across all stages remains below 15%.
NRG1 gene fusions arise from structural DNA rearrangements and typically occur in the absence of other oncogenic alterations. These fusions are best identified using a combination of RNA- and DNA-based next-generation sequencing techniques.
Current systemic first-line treatments for cholangiocarcinoma offer limited clinical benefit, with overall response rates ranging from 26% to 29% and median overall survival of approximately 12 months. Second-line treatment with FOLFOX is associated with an overall response rate of 5%, median progression-free survival of four months, and median overall survival of just over six months. Zenocutuzumab-zbco has demonstrated clinical activity in patients with cholangiocarcinoma driven by NRG1 gene fusions, highlighting its potential as a targeted therapeutic option.
The FDA’s Orphan Drug Designation is granted to therapies intended to treat rare diseases affecting fewer than 200,000 people in the United States. The designation provides incentives including up to seven years of market exclusivity following approval, exemption from certain FDA fees, eligibility for clinical trial tax credits, and increased regulatory support during development.
Zenocutuzumab-zbco, marketed as BIZENGRI®, previously received FDA Breakthrough Therapy Designation in October 2025 and was granted accelerated approval in December 2024 for adults with advanced unresectable or metastatic non-small cell lung cancer and pancreatic ductal adenocarcinoma associated with NRG1 gene fusions.
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