Regulatory & Policy

Partner Therapeutics seeking third indication for Bizengri in NRG1 fusion-positive cholangiocarcinoma

Edited by Robert McTiernan··3 min read

Partner Therapeutics submitted a supplemental Biologics License Application (sBLA) to the US FDA on April 14, 2026 for Bizengri (zenocutuzumab-zbco), seeking approval for adults with advanced unresectable or metastatic cholangiocarcinoma harboring an NRG1 gene fusion. The filing marks the first regulatory submission for Bizengri in this bile duct malignancy with the aim of adding a third indication to the molecule's existing accelerated approvals in NRG1 fusion-positive non-small cell lung cancer and pancreatic adenocarcinoma.

The sBLA seeks approval without restriction to a specific line of therapy, the company said. The filing is supported by data from the eNRGy study, a basket trial evaluating zenocutuzumab-zbco across NRG1 fusion-positive solid tumors. No priority review or accelerated pathway designation was disclosed in the announcement, and the company did not provide a projected PDUFA date.

Bizengri's cholangiocarcinoma data

The cholangiocarcinoma cohort of the eNRGy study generated an overall response rate of 36.8% (95% CI: 16.3, 61.6%) and a median duration of response of 12.9 months, as assessed by blinded independent central review. No patients in that cohort discontinued therapy due to adverse events, the company said. The mechanism underlying the filing differs from all currently approved CCA therapies: zenocutuzumab-zbco is a bispecific antibody that simultaneously blocks HER2/HER3 heterodimerization and NRG1 fusion interactions with HER3, disrupting downstream signaling driven by NRG1 chimeric ligands rather than the chimeric receptors targeted by FGFR inhibitors such as pemigatinib and futibatinib.

NRG1 fusions are estimated to occur in fewer than 2% of cholangiocarcinoma cases, and the source material states that no approved therapies currently target this molecular subgroup in the disease. The rarity of the alteration creates a diagnostic challenge: unlike NTRK, RET, or FGFR fusions, NRG1 fusions produce chimeric ligands that are frequently missed by DNA-only next-generation sequencing panels and require tissue-based RNA testing for reliable detection. Partner Therapeutics noted this in its announcement, with Chief Development Officer Pritesh Gandhi stating that RNA testing is essential to ensure patients with NRG1-driven tumors are identified.

NCCN guidelines

The filing arrives alongside a notable guideline development. The National Comprehensive Cancer Network added zenocutuzumab-zbco to its oncology clinical practice guidelines for biliary tract cancers as a Category 2A subsequent-line therapy and as a Category 2B recommendation for front-line treatment of NRG1 fusion-positive cholangiocarcinoma — the latter positioning preceding any formal regulatory approval for the indication. Dr. James Cleary of Dana-Farber Cancer Institute, commenting in the release, described NRG1 gene fusions as an actionable biomarker in this disease and said the eNRGy data suggest targeted inhibition with zenocutuzumab may represent a meaningful treatment approach.

The AllSci BriefSystematic R&D and deal news. Daily.

The cholangiocarcinoma treatment landscape has undergone substantial change since 2020, when pemigatinib became the first targeted therapy approved in the disease. Ivosidenib followed in 2021 for IDH1-mutant CCA, futibatinib in 2022 for FGFR2 fusion-positive intrahepatic disease, and durvalumab in combination with gemcitabine and cisplatin was approved the same year for first-line biliary tract cancer regardless of biomarker status. Pembrolizumab combined with gemcitabine and cisplatin received approval in 2023 for the same unselected population. Despite this expansion, the molecular subgroup defined by NRG1 fusions has remained without a specifically labeled therapy, and the eNRGy data represent the primary clinical evidence base for this population in CCA.

The sBLA adds to a field where accelerated approval pathways have played a central role, and where the durability of those approvals has varied. Infigratinib, an FGFR1–3 inhibitor that received accelerated approval in 2021 for FGFR2 fusion-positive CCA, was voluntarily withdrawn in 2024 after a confirmatory trial failed to verify clinical benefit — a precedent that underscores the regulatory risk associated with response-rate-based submissions in this disease. The eNRGy cholangiocarcinoma cohort was small, as is typical for trials enrolling rare fusion-defined populations, and the 95% confidence interval for the reported ORR is correspondingly wide.

Bizengri's existing accelerated approvals in NSCLC and pancreatic adenocarcinoma were also granted based on overall response rate and duration of response, with continued approval in those indications contingent on confirmatory trial data. The cholangiocarcinoma sBLA follows the same evidentiary model. Partner Therapeutics holds exclusive US rights to develop and commercialize zenocutuzumab-zbco under an agreement with Merus B.V., a wholly owned subsidiary of Genmab.

Spot something wrong? Report an issue with this article