Partner Therapeutics Announces Publication of Results From the eNRGy Trial of Zenocutuzumab in Patients with NRG1+ Cholangiocarcinoma in Journal of Clinical Oncology (JCO)

News provided by

Jul 02, 2026, 06:30 ET

Zenocutuzumab offers meaningful and durable antitumor activity, substantially reduced toxicity and no treatment‑limiting safety concerns, distinguishing it favorably from existing standards of care

LEXINGTON, Mass., July 2, 2026 /PRNewswire/ -- Partner Therapeutics, Inc. (PTx), a private, fully integrated biotechnology company, announced that results from the cholangiocarcinoma cohort of the eNRGy trial (NCT02912949) have been published in the Journal of Clinical Oncology (JCO).¹ These data supported the recent U.S. Food and Drug Administration (FDA) approval of BIZENGRI^® (zenocutuzumab-zbco) for the treatment of adults with advanced unresectable or metastatic cholangiocarcinoma harboring an NRG1 gene fusion with disease progression on or after prior systemic therapy. The approval was expedited by PTx's receipt of a Commissioner's National Priority Voucher (CNPV) underscoring the urgent unmet need in this patient population.

"The FDA approval of BIZENGRI and the publication of these data in the Journal of Clinical Oncology highlight the clinical relevance of the eNRGy trial and reinforces our commitment to advancing therapies for patients with unmet medical needs, including those with NRG1 fusion-positive cholangiocarcinoma. The JCO publication further supports the therapeutic potential of zenocutuzumab in this rare population, which has historically experienced limited treatment options and poor outcomes with chemotherapy."

— Fiona Garner, Executive Director, Clinical Development, Partner Therapeutics

Data in NRG1+ Cholangiocarcinoma

The eNRGy trial is a multicenter, open-label, phase 2 study evaluating zenocutuzumab in adults with advanced solid tumors harboring NRG1 gene fusions. Data published in JCO include 22 patients with unresectable or metastatic NRG1 fusion-positive cholangiocarcinoma, of whom 19 were evaluable for efficacy. Most patients were pre-treated, with a median of one prior line of therapy (range up to 6). Notably, RNA-based next-generation sequencing (NGS) identified 100% of NRG1 fusions, compared with 29% detected by DNA-based testing.

The investigator-assessed overall response rate (ORR), defined as the proportion of patients with tumor shrinkage or disappearance, was 36.8%. Median duration of response was 7.4 months, and median progression-free survival was 9.2 months. The clinical benefit rate was 57.9%, defined as the percentage of patients achieving a complete or partial response or stable disease lasting longer than 6 months.

Zenocutuzumab was generally well tolerated. Most treatment-related adverse events were grade 1-2, with diarrhea (27.3%), fatigue (18.2%), and nausea (13.6%) being reported most frequently. No patients discontinued treatment due to treatment-related adverse events.

"The FDA approval of zenocutuzumab and the publication of these data represent important progress for patients with NRG1 fusion–positive cholangiocarcinoma. Limited efficacy and poor tolerability of second-line chemotherapy remain a significant clinical challenge in the treatment of patients with advanced cholangiocarcinoma. Zenocutuzumab provided meaningful tumor responses, durable clinical benefit, and a favorable tolerability profile. These findings also underscore the critical importance of comprehensive molecular testing—particularly tissue-based RNA sequencing—to reliably identify NRG1 gene fusions and ensure patients are matched with appropriate targeted therapy."

— James M. Cleary, MD, PhD, Director, Clinical Research, Division of Gastrointestinal Oncology, Dana-Farber Cancer Institute; and senior author.

FDA Approval in Three NRG1+ Solid Tumors

BIZENGRI was first FDA approved under accelerated approval in 2024 for advanced, unresectable or metastatic non-small cell lung cancer and pancreatic adenocarcinoma for patients harboring an NRG1 gene fusion on or after systemic therapy. In May 2026, BIZENGRI received FDA approval for advanced, unresectable or metastatic cholangiocarcinoma for patients harboring an NRG1 gene fusion on or after systemic therapy. Additionally, zenocutuzumab is included in the National Comprehensive Cancer Network^® (NCCN^®) Clinical Practice Guidelines in Oncology (NCCN Guidelines^®) for non-small cell lung cancer, pancreatic adenocarcinoma, and cholangiocarcinoma.

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

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 typically occur in patients who are otherwise driver negative, 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.

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 activating 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.*

BIZENGRI is indicated 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.

*This indication is approved under accelerated approval based on overall response rate and duration of response. Continued approval for this indication 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 (n=99). 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 transferase (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 (n=39).

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 transferase (23%), decreased hemoglobin (23%), vomiting (23%), nausea (23%), decreased leukocytes (21%), and fatigue (21%).

NRG1 Gene Fusion Positive Advanced, Unresectable or Metastatic Cholangiocarcinoma

Serious adverse reactions occurred in 23% of patients with NRG1 gene fusion positive cholangiocarcinoma who received BIZENGRI (n=22).

In patients with NRG1 gene fusion positive cholangiocarcinoma who received BIZENGRI the most common (≥20%) adverse reactions, including laboratory abnormalities, were decreased magnesium (59%), increased alanine aminotransferase (50%), fatigue (46%), decreased platelets (46%), decreased hemoglobin (41%), increased aspartate aminotransferase (41%), increased alkaline phosphatase (41%), decreased phosphate (41%), diarrhea (41%), abdominal pain (36%), musculoskeletal pain (36%), increased gamma-glutamyl transferase (36%), increased bilirubin (32%), decreased potassium (32%), decreased sodium (32%), nausea (27%), cough (27%), increased activated partial thromboplastin time (aPTT) (27%), dyspnea (23%), decreased appetite (23%), and decreased albumin (23%).

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 (US: LEUKINE^®; EU: IMREPLYS^®; and with Nobelpharma Co. Ltd for JAPAN: SARGMALIN^®). Visit www.partnertx.com.

Reference:
1. Cleary JM, Springfeld C, Arnold D, et al. Efficacy and tolerability of zenocutuzumab in advanced NRG1 fusion-positive cholangiocarcinoma: Results from the eNRGy phase 2 trial. J Clin Oncol. 2026. doi:10.1200/JCO-25-03128

NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way.

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.

SOURCE Partner Therapeutics, Inc.