With positive data from the Phase III HERIZON-GEA-01 study, Zymeworks and Jazz Pharmaceuticals will file an approval application for Ziihera in the first half of 2026 for the treatment of gastroesophageal adenocarcinoma.
Jazz Pharmaceuticals and Zymeworks’ HER2 bispecific antibody Ziihera significantly improved progression-free survival in a Phase III study of patients with gastroesophageal adenocarcinoma, clearing the way for a regulatory filing.
The partners plan to file a supplemental biologics license application in the first half of 2026, seeking approval for Ziihera as a first-line option for patients with HER2-positive, locally advanced or metastatic gastroesophageal adenocarcinoma (GEA). China’s BeOne Medicines is also collaborating with Jazz and Zymeworks on the development of Ziihera.
Analysts at Leerink Partners said that the Ziihera regimens could “be able to replace Herceptin in GEA across the spectrum of” PDL1-positive and PLD1-negative patients. “These results exceeded our base case assumption which only assumed usage in the PDL1 negative subset,” they added in a note to investors Monday, increasing their peak GEA revenue forecast for Ziihera to around $2.9 billion.
Herceptin is marketed by Roche’s Genentech and has long been a stalwart in breast and gastric cancers.
Jefferies was similarly effusive about the Ziihera data, writing on Monday that the HERIZON-GEA-01 results “are practice-changing and may elevate Ziihera as the preferred HER2-targeting backbone in 1L GEA.”
Data released on Monday come from the Phase III HERIZON-GEA-01 study, which enrolled around 920 patients with unresectable locally advanced, recurrent or metastatic GEA positive for the HER2 marker. Ziihera was administered with either a doctor’s choice of chemotherapy or with BeOne’s Tevimbra plus chemo. Controls were given Roche’s Herceptin plus chemotherapy.
Without revealing specific data, the companies claimed that patients given either Ziihera-based regimen saw “highly statistically significant and clinically meaningful improvements” in progression-free survival versus controls. The Ziihera combos also led to better overall survival and the drug met key secondary endpoints such as objective response rate and duration of response.
The companies promised to present HERIZON-GEA-01 data at an upcoming medical meeting early next year.
Administered intravenously, Ziihera is a bispecific antibody that binds to two sites on the HER2 protein, triggering the internalization of the receptor. This mechanism leads to an overall reduction of the number of HER2 receptors on the surface of cancer cells, which in turn suppresses their ability to grow and divide uncontrollably. Ziihera also induces the immune system’s cancer-killing activity.
Ziihera was originally developed by Zymeworks, which entered into a pact with BeOne (known as BeiGene at the time) in November 2018. Zymeworks then signed a licensing deal with Jazz in October 2022.
