(NewsNation) — Stocks climbed Wednesday morning after Moderna and Merck announced that an experimental cancer vaccine showed positive initial results in its first late-stage trial.

Moderna stock soared over 90%, and Merck's shares climbed more than 9% in morning trading. The size reflects the companies' relative size, with Merck's market cap at around $333 billion while Moderna's neared $25 billion.

The mRNA shot in combination with Merck's immunotherapy Keytruda met the key goals in more than 1,100 patients with higher-risk or advanced-stage melanoma whose detectable cancer had been surgically removed. The combination met the main study goal of extending the time patients lived without their melanoma returning compared to Keytruda alone. The trial also found that the combination reduced the risk of cancer spreading to distant parts of the body.

 Kindergarten vaccination rates continue to decline: CDC data 

Every tumor has a unique set of mutations; the personalized vaccine is designed to target the specific mutations in each patient's tumor.

"These Phase 3 findings represent a pivotal moment for the field of cancer research," said CEO of Moderna Stephane Bancel in a statement released by the company. "For many years, the idea of creating an mRNA treatment designed specifically for an individual patient's cancer was aspirational. We are now helping turn that vision into a reality."

 Cancer study: Patients in areas with higher medical debt face grimmer futures 

Melanoma cases have been rising over the past few decades, with more than 330,000 cases diagnosed in 2022. It is estimated there will be 112,000 new cases of melanoma diagnosed and over 8,500 deaths in the U.S. during 2026. Despite advances in treatment, patients with surgically removed melanoma remain at risk for disease recurrence.

Moderna and Merck plan to present the data at an upcoming international meeting.

Copyright 2026 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

For the latest news, weather, sports, and streaming video, head to NewsNation.