Moderna and Merck will jointly develop a cancer vaccine for high-risk melanoma patients
Pipettes are seen at the Moderna Inc. lab in Cambridge, Massachusetts, on Nov. 14, 2017.

Moderna and Merck will jointly develop and sell a cancer vaccine that is personalized for individual patients, the companies announced Wednesday.

Moderna's vaccine, based on its messenger RNA technology, is being studied in combination with Merck's Keytruda to treat patients with high-risk melanoma, the deadliest form of skin cancer, in a phase two trial. The companies expect to report data in the fourth quarter of this year.

Moderna's stock jumped 16% in morning trading before giving up some of that advance. The company's shares were up about 10% in afternoon trading.

Moderna's vaccine is designed to trigger the immune system to deploy killer T cells that target the specific mutations of a patient's tumors. Merck's Keytruda is a monoclonal antibody, administered as an injection, that prevents certain cell proteins from stopping T cells from going on the attack.

The companies originally entered the agreement in 2016, but Merck is now exercising its option through a $250 million payment to Moderna. Merck will collaborate on the development and commercialization of the product. The companies will share all costs and profits equally.

Moderna became a household name during the pandemic after developing one of the most successful vaccines against Covid-19 in collaboration with the U.S. National Institutes of Health.

But the Covid vaccine is Moderna's only commercially available product. The Boston biotech company is under growing pressure to demonstrate how its messenger RNA technology can be deployed against other diseases.

Moderna expects $21 billion in Covid vaccine sales this year as it rolls out new booster shots that target the omicron variant.

Keytruda is Merck's biggest drug, making up 35% of the company's total sales in the second quarter. It has been approved by the Food and Drug Administration to treat several different types of cancer.