Voucher Recognizes High Unmet Medical Need in Ultra-Rare, Molecularly Defined Cholangiocarcinoma  

LEXINGTON, Mass. – May 06, 2026 – Partner Therapeutics, Inc. (PTx), a private, fully integrated biotechnology company, today announced that the U.S. Food and Drug Administration (FDA) has awarded a Commissioner’s National Priority Voucher (CNPV) pilot program voucher for BIZENGRI^® (zenocutuzumab-zbco) for the treatment of adults with advanced, unresectable or metastatic cholangiocarcinoma harboring a neuregulin 1 (NRG1) gene fusion with disease progression on or after prior systemic therapy. PTx submitted a supplemental Biologics License Application (sBLA) to the FDA for this indication based on data from the Phase 2 eNRGy trial. BIZENGRI previously received Breakthrough Therapy Designation and Orphan Drug Designation from the FDA for NRG1+ cholangiocarcinoma.  

“We are honored to receive this Commissioner’s National Priority Voucher, which reflects the FDA’s recognition of the profound unmet need facing patients with NRG1+ cholangiocarcinoma, an ultra-rare cancer for which no approved targeted therapy currently exists,” said Pritesh J. Gandhi, Chief Development Officer, Partner Therapeutics. “Receiving this voucher highlights the urgent need for new treatment options in NRG1 fusion-positive cholangiocarcinoma. Based on the encouraging data from the eNRGy trial, including meaningful tumor responses, durable benefit and a favorable tolerability profile, we believe BIZENGRI has the potential to address a critical gap in care for these patients. We look forward to working closely with the FDA through this accelerated review process.”  

The FDA’s Commissioner’s National Priority Voucher pilot program, announced in June 2025, is designed to reduce drug and biologic review times from the standard 10–12 months to as little as 1–2 months for products that align with one or more U.S. national health priorities. These priorities focus on advancing innovative breakthrough therapies that introduce novel mechanisms and meaningfully improve how diseases are treated, while also addressing significant unmet medical needs where current treatment options fall short for patients. The program employs a multidisciplinary, tumor board-style review process involving the primary FDA review team and senior agency leadership. BIZENGRI, as a first-in-class bispecific antibody targeting a rare and actionable oncogenic driver with no approved targeted therapy, aligns directly with national priorities. 

“For patients facing cholangiocarcinoma, innovation and timely diagnosis can make a profound difference. The FDA’s recognition of this potential treatment underscores both the unmet need in this rare biomarker-defined population and the importance of expanding access to comprehensive biomarker testing so patients can be matched to the most appropriate therapies as early as possible,” said Stacie Lindsey, CEO of the Cholangiocarcinoma Foundation. 

Data from the cohort of patients with NRG1+ cholangiocarcinoma in the Phase 2 eNRGy trial were presented at the AACR-NCI-EORTC Meeting in October 2025, highlighting clinical outcomes in this rare cancer.¹ “Patients with NRG1 fusion–positive cholangiocarcinoma face a significant unmet need, with limited effective treatment options available today,” said Alison Schram, MD, Gynecologic Medical Oncologist at Memorial Sloan Kettering Cancer Center (MSK) and Principal Investigator of the eNRGy trial. “The FDA’s recognition through the Commissioner’s National Priority Voucher program emphasizes the urgency of advancing therapies for this population. In the eNRGy study, zenocutuzumab demonstrated clinically meaningful activity, with objective responses in more than one-third of evaluable patients and a median progression-free survival of over nine months. These data also highlight the critical role of comprehensive molecular testing, particularly RNA-based comprehensive molecular profiling, in identifying patients who may benefit from emerging targeted approaches.”  

About NRG1+  Cholangiocarcinoma
Cholangiocarcinoma is a rare, aggressive malignancy of the bile ducts with an all-stage 5-year overall survival of less than 15%. NRG1 gene fusions occur in fewer than 1% of cholangiocarcinoma cases. NRG1 fusions are largely mutually exclusive with other actionable oncogenic drivers, leaving affected patients—many of whom are younger adults —without approved targeted therapy. Standard cytotoxic regimens carry substantial toxicity, and second-line options such as FOLFOX produce objective responses in only approximately 5% of patients. 

For more information on the eNRGy trial and zenocutuzumab-zbco, please visit www.partnertx.com. 

About NRG1 Gene Fusions
NRG1 fusions are unique cancer drivers that create oncogenic chimeric ligands rather than the more widely described chimeric receptors (NTRK, RET, ROS1, ALK, and FGFR fusions). The chimeric ligands bind to HER3, triggering HER2/HER3 heterodimerization and activate downstream signaling pathways that cause cancer cells to grow and proliferate. Zenocutuzumab-zbco is a bispecific antibody that blocks HER2/HER3 dimerization and NRG1 fusion interactions with HER3, resulting in the suppression of these pathways. Comprehensive molecular testing, notably the combination of tissue-based DNA and RNA next generation sequencing, is essential to identify rare and actionable gene fusions like NRG1. 

About BIZENGRI (zenocutuzumab-zbco) 

INDICATIONS
BIZENGRI is indicated for the treatment of adults with advanced unresectable or metastatic non-small cell lung cancer (NSCLC) harboring a neuregulin 1 (NRG1) gene fusion with disease progression on or after prior systemic therapy. 

BIZENGRI is indicated for the treatment of adults with advanced unresectable or metastatic pancreatic adenocarcinoma harboring a neuregulin 1 (NRG1) gene fusion with disease progression on or after prior systemic therapy. 

These indications are approved under accelerated approval based on overall response rate and duration of response. Continued approval for these indications may be contingent upon verification and description of clinical benefit in a confirmatory trial(s). 

Important Safety Information 

BOXED WARNING: EMBRYO-FETAL TOXICITY 

Embryo-Fetal Toxicity: Exposure to BIZENGRI during pregnancy can cause embryo-fetal harm. Advise patients of this risk and the need for effective contraception. 

WARNINGS AND PRECAUTIONS 

Infusion-Related Reactions/Hypersensitivity/Anaphylactic Reactions
BIZENGRI can cause serious and life-threatening infusion-related reactions (IRRs), hypersensitivity and anaphylactic reactions. Signs and symptoms of IRR may include chills, nausea, fever, and cough. 

In the eNRGy study, 13% of patients experienced IRRs, all were Grade 1 or 2; 91% occurred during the first infusion. 

Administer BIZENGRI in a setting with emergency resuscitation equipment and staff who are trained to monitor for IRRs and to administer emergency medications. Monitor patients closely for signs and symptoms of infusion reactions during infusion and for at least 1 hour following completion of first BIZENGRI infusion and as clinically indicated. Interrupt BIZENGRI infusion in patients with ≤ Grade 3 IRRs and administer symptomatic treatment as needed. Resume infusion at a reduced rate after resolution of symptoms. Immediately stop the infusion and permanently discontinue BIZENGRI for Grade 4 or life-threatening IRR or hypersensitivity/anaphylaxis reactions.

Interstitial Lung Disease/Pneumonitis
BIZENGRI can cause serious and life-threatening interstitial lung disease (ILD)/pneumonitis. 

In the eNRGy study, ILD/pneumonitis occurred in 2 (1.1%) patients treated with BIZENGRI. Grade 2 ILD/pneumonitis (Grade 2) resulting in permanent discontinuation of BIZENGRI occurred in 1 (0.6%) patient. Monitor for new or worsening pulmonary symptoms indicative of ILD/pneumonitis (e.g., dyspnea, cough, fever). Immediately withhold BIZENGRI in patients with suspected ILD/pneumonitis and administer corticosteroids as clinically indicated. 

Permanently discontinue BIZENGRI if ILD/pneumonitis ≥ Grade 2 is confirmed. 

Left Ventricular Dysfunction
BIZENGRI can cause left ventricular dysfunction. 

Left ventricular ejection fraction (LVEF) decrease has been observed with anti-HER2 therapies, including BIZENGRI. Treatment with BIZENGRI has not been studied in patients with a history of clinically significant cardiac disease or LVEF less than 50% prior to initiation of treatment. 

In the eNRGy study, Grade 2 LVEF decrease (40%-50%; 10 – 19% drop from baseline) occurred in 2% of evaluable patients. Cardiac failure without LVEF decrease occurred in 1.7% of patients, including 1 (0.6%) fatal event. 

Before initiating BIZENGRI, evaluate LVEF and monitor at regular intervals during treatment as clinically indicated. For LVEF of less than 45% or less than 50% with absolute decrease from baseline of 10% or greater which is confirmed, or in patients with symptomatic congestive heart failure (CHF), permanently discontinue BIZENGRI.

Embryo-Fetal Toxicity
Based on its mechanism of action, BIZENGRI can cause fetal harm when administered to a pregnant woman. No animal reproduction studies were conducted with BIZENGRI. In post marketing reports, use of a HER2-directed antibody during pregnancy resulted in cases of oligohydramnios manifesting as fatal pulmonary hypoplasia, skeletal abnormalities, and neonatal death. In animal models, studies have demonstrated that inhibition of HER2 and/or HER3 results in impaired embryo-fetal development, including effects on cardiac, vascular and neuronal development, and embryolethality. Advise patients of the potential risk to a fetus. Verify the pregnancy status of females of reproductive potential prior to the initiation of BIZENGRI. Advise females of reproductive potential to use effective contraception during treatment with BIZENGRI and for 2 months after the last dose.

ADVERSE REACTIONS

NRG1 Gene Fusion Positive Unresectable or Metastatic NSCLC 

Serious adverse reactions occurred in 25% of patients with NRG1 gene fusion positive NSCLC who received BIZENGRI. Serious adverse reactions in ≥ 2% of patients included pneumonia (n=4) dyspnea and fatigue (n=2 each). Fatal adverse reactions occurred in 3 (3%) patients and included respiratory failure (n=2), and cardiac failure (n=1). Permanent discontinuation of BIZENGRI due to an adverse reaction occurred in 3% of patients. Adverse reactions resulting in permanent discontinuation of BIZENGRI included dyspnea, pneumonitis and sepsis (n=1 each). 

In patients with NRG1 gene fusion positive NSCLC who received BIZENGRI, the most common (>20%) adverse reactions, including laboratory abnormalities, were decreased hemoglobin (35%), increased alanine aminotransferase (30%), decreased magnesium (28%), increased alkaline phosphatase (27), decreased phosphate (26%), diarrhea (25%), musculoskeletal pain (23%), increased gamma-glutamyl transpeptidase (23%), increased aspartate aminotransferase (22%), and decreased potassium (21%).

NRG1 Gene Fusion Positive Unresectable or Metastatic Pancreatic Adenocarcinoma 

Serious adverse reactions occurred in 23% of patients with NRG1 gene fusion positive pancreatic adenocarcinoma who received BIZENGRI. 

There were 2 fatal adverse reactions, one due to COVID-19 and one due to respiratory failure. 

In patients with NRG1 gene fusion positive pancreatic adenocarcinoma who received BIZENGRI the most common (≥20%) adverse reactions, including laboratory abnormalities, were increased alanine aminotransferase (51%), diarrhea (36%), increased aspartate aminotransferase (31%), increased bilirubin (31%), decreased phosphate (31%), increased alkaline phosphatase (28%), decreased sodium (28%), musculoskeletal pain (28%), decreased albumin (26%), decreased potassium (26%), decreased platelets (26%), decreased magnesium (24%), increased gamma-glutamyl transpeptidase (23%), decreased hemoglobin (23%), vomiting (23%), nausea (23%), decreased leukocytes (21%), and fatigue (21%). 

Please see full Prescribing Information, including Boxed Warning 

About Partner Therapeutics
Partner Therapeutics, Inc. (PTx), an integrated biotechnology company, focuses on development and commercialization of therapeutics to improve health outcomes in cancer and serious diseases, as well as global health security threats. The company believes in delivering products and supporting medical teams with the purpose of achieving superior outcomes for patients and their families. PTx’s portfolio includes zenocutuzumab-zbco (BIZENGRI^®) and sargramostim (EU: IMREPLYS^®; US: LEUKINE^®; and with Nobelpharma Co. Ltd for JAPAN: SARGMALIN^®). Visit www.partnertx.com. 

References: 

1. Schram AM, Clearly JM, Arnold D, et al. Zenocutuzumab efficacy and safety in advanced NRG1+ cholangiocarcinoma: Analysis from the phase 2 eNRGy trial [abstract]. Mol Cancer Ther. 2025;24(10_Supplement):A102. 

BIZENGRI^® is a registered trademark of Merus B.V., a wholly owned subsidiary of Genmab A/S. Under an agreement with Merus, PTx has exclusive rights to develop, manufacture, and commercialize zenocutuzumab-zbco for the treatment of NRG1+ cancer in the U.S. and provide the product on a named-patient basis for this use outside of the U.S. pending future regulatory developments. 

PARTNER THERAPEUTICS^®, ^®, IMREPLYS^®, and LEUKINE^® are registered trademarks owned by Partner Therapeutics, Inc. ©2026 Partner Therapeutics, All rights reserved. 

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