Updated Version 3 – Merck/Moderna Cancer Vaccine Can Reduce Melanoma Death or Recurrence Risk by 42%, Stock Price Falls

Additional details from the Moderna CEO interview are included in paragraphs 10-12, and analyst comments are added in paragraph 17.

Michael Erman/Julie Steenhuysen

Reuters, October 22 - Moderna MRNA.O and Merck MRK.N said on Thursday that, in a large clinical trial, their mRNA cancer vaccine combined with Merck’s widely used immunotherapy reduced the risk of death or recurrence from melanoma by 42%, potentially paving the way for a new era of personalized treatments.

Since the two companies announced the trial’s success in August (link) (at that time, actual data were not disclosed), Moderna’s stock price has soared nearly fourfold, closing up by Wednesday. After the trial results were leaked on an oncology website early Thursday, the stock closed down more than 17%. Merck’s share price closed down about 1.8%.

Data from this phase III study involving more than 1,100 patients also showed that the combination therapy reduced the risk of cancer spreading by 38%.

This is the first dataset to show that combining a vaccine based on mutations unique to each patient’s tumor with a drug that boosts the immune system’s ability to fight cancer can effectively curb disease progression. The vaccine, named intismeran autogene, was tested alongside Merck’s blockbuster immunotherapy drug Keytruda (one of the world’s best-selling medicines).

Some analysts said this data could raise investors’ concerns about whether this technology can be broadly applied to other cancers.

Keytruda works by releasing the natural “brakes” cancer cells use to evade immune system attacks, while the vaccine instructs patients’ cells to produce copies of specific mutations for the immune system to seek out and destroy.

Moderna CEO Stephane Bancel said these data mark a new chapter in cancer treatment.

“With the ability to generate new T cells targeting specific tumors...the clinical impact is profound, and as we saw in phase II, this effect is very durable,” Bancel said in an interview.

Bancel said the two companies are preparing to file for U.S. approval and expect the cancer vaccine to hit the market in 2027.

The intismeran and Keytruda combination therapy is currently being tested in a variety of other cancers, including kidney, bladder, and lung cancer.

Bancel stated that he believes the vaccine should enhance efficacy “in all areas where Keytruda works,” but how much improvement it provides remains to be seen. Keytruda is approved for 19 types of cancer.

The CEO also said intismeran could be used as a standalone therapy for early-stage cancers.

Results from the phase III melanoma study, based on the first two years of patient data after treatment, are scheduled to be presented Saturday at the European Society for Medical Oncology annual meeting in Madrid.

Among patients who received the vaccine in addition to Keytruda, 82.2% had no cancer recurrence two years later, compared to 70% of those who received only Keytruda.

“This result is statistically highly significant and certainly not a chance finding,” said Dr. Hussein Tawbi, melanoma specialist at the University of Texas MD Anderson Cancer Center and clinical trial investigator, commenting on the outcome.

Several Wall Street analysts said before the meeting that investors expected the combination therapy to reduce the recurrence risk by 40% or more.

“Across oncology, we see expectations for pricing of the multibillion-dollar (intismeran) pipeline gradually diminishing,” wrote RBC analyst Trung Huynh. “This data makes us less optimistic, as melanoma should have been the best-case scenario.”

The trial tested nine doses of the vaccine in combination with Keytruda, starting treatment 13 weeks after surgical removal of melanoma lesions. The study compared the combined therapy to patients receiving only Keytruda, which is the standard treatment for melanoma.

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