Jazz Pharmaceuticals and Zymeworks Report Positive Cancer Treatment Results. The Stocks Soar.

Jazz Pharmaceuticals is one of Zymeworks’ development and commercialization partners. (Dreamstime)

Key Points

• Jazz Pharmaceuticals and Zymeworks report positive Phase 3 trial results for their cancer drug Ziihera.
• Ziihera, combined with chemotherapy, improves progression-free survival in patients with gastroesophageal adenocarcinoma.
• Shares of both Jazz Pharmaceuticals and Zymeworks rise sharply.

Shares of Jazz Pharmaceuticals and Zymeworks soared Monday after the drugmakers reported positive results in a late-stage trial for their cancer treatment.

Combined with chemotherapy in a Phase 3 trial, the drug Ziihera showed clinically meaningful improvements in progression-free survival for patients with gastroesophageal adenocarcinoma, or GEA. Jazz acquired the development and commercialization rights to what is now known as Ziihera from Zymeworks in 2022.

Jazz stock jumped 18% and Zymeworks shares climbed 34%. Jazz was on track for its highest close since April 25, 2022, and Zymeworks was headed for its largest single-day gain on record, according to Dow Jones Market Data. BeOne Medicines , which has commercialization rights to Ziihera in the Asia-Pacific region, rose 4.9%.

“We believe these results will be practice changing, and highlight the potential impact of Ziihera for patients who are facing a devastating diagnosis and limited options in locally advanced or metastatic GEA,” said Rob Iannone, M.D., chief medical officer at Jazz.

Barron’s highlighted Jazz last month as one of the healthcare stocks driving a year-end rally for the industry.

Jazz plans to submit the results for presentation at a medical meeting in the first quarter of 2026 and for publication in a peer-reviewed journal, the company said. It will also submit for adoption in the National Comprehensive Cancer Network Guidelines for oncology treatment.

Write to Nate Wolf at nate.wolf@barrons.com