Merck MRK.N and Moderna MRNA.O said on Wednesday a study of a personalized mRNA vaccine combined with the immunotherapy drug Keytruda reduced melanoma skin cancer recurrence and spread compared with Keytruda alone, the first positive late-stage trial results for an mRNA cancer vaccine.

The trial is ongoing, but interim results found the treatment, known as Intismeran, met both its primary target of reducing cancer recurrence and its secondary goal of keeping cancers from spreading to other parts of the body.

The treatment combines Merck’s Keytruda with a made-to-order mRNA vaccine from Moderna that is based on an analysis of mutations found in the patients’ own tumors.

The trial enrolled 1,137 high-risk patients with stage IIB-IV melanoma that had been surgically removed.

Volunteers were randomized to receive up to nine doses of Keytruda plus the personalized vaccine or Keytruda alone for about one year. The companies said no new safety signals have emerged in the trial.

In January, the companies announced results of a mid-stage trial of the treatment showing that it reduced the risk of recurrence or death by 49% after five years.

The companies said they will present their results at an upcoming medical meeting and share them with regulators.

Melanoma is the deadliest form of skin cancer. In 2023, there were more than 1.5 million people in the U.S. living with melanoma, according to the National Cancer Institute.

Moderna shares surge after trial success

The success of the late-stage trial sent the biotech’s shares surging 90% in premarket trading.

Shares of Moderna were trading at $118.61, while Merck climbed 7.5% before the bell. Moderna was the No. 1 trending stock on retail-investor forum Stocktwits, according to the platform.

The data will likely ease investor worries over the companies’ long-term growth drivers. Moderna has been looking for growth beyond its COVID-19 shot while Merck is bracing for the looming patent loss for Keytruda, its blockbuster therapy, later this decade.

William Blair analyst Myles Minter said the interim results position both companies well to seek regulatory approval, while also reading positively for the vaccine’s ongoing studies in other types of cancer.

Merck’s R&D head Dean Li, in an appearance on CNBC, said the companies expect to begin talks with regulators in the next few months.

Last month, Barclays analysts said they expect the therapy could generate about $3 billion for treating melanoma by 2035.

No pricing yet for cancer treatment

J.P. Morgan analysts said the launch of the vaccine, Intismeran, in adjuvant melanoma will be key to Moderna returning to profitability.

Moderna CEO Stephane Bancel, appearing on CNBC alongside Li, said the companies have not decided on pricing, saying the data had only become available “a couple days ago”.

He said the treatment does not use patients’ own cells, unlike some personalized cell therapies, which could allow the manufacturing process to be scaled and the price reduced.

Melanoma is the deadliest form of skin cancer. In 2023, there were more than 1.5 million people in the U.S. living with melanoma, according to the National Cancer Institute.