Dive Brief:

• The Food and Drug Administration has expanded use of Jazz Pharmaceuticals’ cancer treatment Ziihera, approving Tuesday the treatment as part of a new frontline regimen for HER2-positive gastrointestinal cancers.
• Jazz and partner Zymeworks — the drug’s original developer — first won an accelerated clearance for Ziihera in late-line biliary tract cancer in 2024. Use in that setting earned Jazz $24.8 million in revenue in 2025. The latest clearance opens up a market opportunity north of $1.5 billion, wrote RBC Capital Markets analyst Leonid Timashev, whose team expects “relatively quick uptake.”
• HER2-positive gastroesophageal cancers have long been treated with Roche’s Herceptin, an antibody drug that now faces biosimilar competition. In Jazz’s Phase 3 trial, combinations of Ziihera and chemotherapy with or without the immunotherapy Tevimbra reduced the risk of progression or death by 35% and the risk of death, specifically, by 28% when compared to Herceptin and chemo.

Dive Insight:

Jazz has two blockbuster drugs in its portfolio. Both are in neuroscience in the guise of the epilepsy drug Epidiolex and sleep medication Xywav. Jazz’s forays into oncology have proved less lucrative, as none of its other cancer drugs have become $1 billion-plus sellers.

Ziihera could be different. Around 12,000 people in the U.S. alone may now be eligible for treatment, substantially more than the 1,500 estimated to have the biliary tract cancer Ziihera is also cleared for, Stifel analyst Annabel Samimy wrote in a note to clients.

Samimy and RBC’s Timashev both noted that the FDA authorized broad use in people with lower levels of HER2 expression, even though the key study supporting Ziihera’s benefits had many more volunteers with high HER2 levels. The drug’s prescribing information also endorses use in tumors in the esophagus and the junction of the stomach and esophagus, even though most trial participants had cancer inside the stomach.

The FDA didn’t put many safety limits on the drug, either, the analysts wrote. A warning about severe diarrhea was added to the drug’s label because it occurred so often, but may have been included to get patients to adhere to anti-diarrheal treatment while undergoing Ziihera therapy, Samimy wrote. Her team forecasted $650 million to $700 million in U.S. sales related to gastroesophageal cancers.

Ziihera’s revenue potential could climb higher still if it’s successful in breast cancer. Jazz is testing Ziihera in a number of settings for breast tumors. Data from the first of those studies could emerge in late 2027.

Jazz acquired most rights to Ziihera through a 2022 deal with Zymeworks. Following the positive results in gastrointestinal cancer last year, Zymeworks changed course to focus on deriving revenue from drug royalties rather than by selling its own medicines. It earned a $250 million payment for the latest approval, and stands to receive another $1.3 billion in milestones, plus royalties, from the collaboration.

Zymeworks also banked an $81 million payment from BeOne Medicines, which owns rights to Ziihera in Asia, Australia and New Zealand.