Investors had been pessimistic about the probability of success for the personalized cancer vaccine intismeran autogene, so the Phase 3 win was a welcome surprise.
The success of Merck’s Moderna-partnered melanoma vaccine didn’t just validate the idea of individualized cancer vaccines; it showed the world how the oncology juggernaut will likely thrive despite the upcoming loss of king Keytruda.
Merck’s shares ended Wednesday trading up 12% to $152.20, reflecting strong investor enthusiasm after the Phase 3 INTerpath-001 study succeeded. Moderna also had a great day at the markets, closing with shares skyrocketing 176% to $174.38.
Patients who received a combination of Keytruda and intismeran autogene, an mRNA-based cancer vaccine, lived longer without their cancer returning than did those who received Keytruda alone, achieving the trial’s primary endpoint of recurrence-free survival.
The results show that Merck has a path to growth even without managing to expand the exclusivity period for Keytruda, analysts said on Wednesday afternoon.
“Merck sentiment continues to improve as Keytruda solution becomes clearer,” BMO Capital Markets wrote. “While Merck may not be able to outright grow through the Keytruda [loss of exclusivity], updates like INTerpath-001 give us further confidence that the company has a meaningful revenue growth strategy for the business beyond just Keytruda.”
Keytruda, the immuno-oncology mega-blockbuster, has been approved in dozens of oncology indications. It has reached the top of pharma’s sales charts, only to recently be eclipsed by Eli Lilly’s GLP-1 franchise. The drug will begin sliding off its patent in 2028, despite Merck’s efforts to get a new formulation approved.
To offset the expected decline, Merck has been working on new antibody-drug conjugates such as the TROP2-directed candidate sac-TMT and other emerging cancer modalities to bulk up its pipeline. And last September, the FDA greenlit a subcutaneous version of Keytruda, which could help to buttress sales.
But investors remain concerned about the loss of Keytruda.
They had not thrown a lot of weight behind the Moderna cancer program, meaning the successful trial result was a happy surprise. BMO said investors had viewed neoantigen trials like INTerpath-001 as risky, given mixed data to date and the novelty of the idea.
“With most expecting trial failure, positive results position Merck and Moderna to move forward with intismeran in cutaneous melanoma,” BMO said.
That means the companies could now have a program worth $2 billion in unadjusted peak revenue in melanoma alone, BMO predicted—with potential across other solid tumors. Merck will, of course, split the profits with Moderna 50/50, but this revenue stream is brand new to investor expectations since they had been so skeptical.
With multiple indications, Merck and Moderna could see $5.6B in unadjusted peak revenue, according to the analysts.
Intismeran is being tested in other solid tumors, including renal cell carcinoma, lung cancer and other advanced types of melanoma. The Phase 2 renal cell trial will read out first in April 2027, according to BMO.
“While translation in efficacy from melanoma to other solid tumors is not certain, we do see reason to be more optimistic about the opportunity in these indications given today’s results,” the firm said.
Merck and Moderna will reveal more detailed data from the INTerpath-001 program at an upcoming medical meeting, Guggenheim noted.
“While we wait to see the full data, if they are as encouraging as they now appear, INT could represent an important part of MRK’s growth story as it works to navigate through biosimilar and pricing pressure for Keytruda starting later this decade,” the firm wrote Wednesday.
