Moderna’s (MRNA) leaked cancer-vaccine trial results looked “promising” on the surface, yet the biotech stock came under intense pressure late on Thursday and was weak on Friday morning too, although the stock regained the losses and was trading higher later in the session.
In fact, MRNA slipped through its 20-day moving average (MA) this week, indicating bears have taken back control of the near-term.
Despite recent weakness, however, Moderna stock remains a blockbuster investment for 2026, currently trading at more than 6x its price at the start of this year.
Why Moderna stock keeps sliding?
The Phase 3 leaked trial data showed that “intismeran autogene” – Moderna’s personalized cancer vaccine – combined with Merck’s Keytruda reduced the risk of melanoma recurrence or death by 42% versus Keytruda alone.
It also lowered the risk of distant metastasis or death by 38%. Those are meaningful clinical gains, and the companies reported no new safety signals.
But the market had already rewarded the study’s success following August’s initial announcement.
The detailed findings therefore needed to improve expectations further.
Bloomberg reported that analysts questioned whether the melanoma results justified confidence in a much broader cancer franchise.
For MRNA shares, that distinction matters – demonstrating that one treatment works supports its development, while supporting a premium valuation requires a credible path to commercial revenue across a larger market.
Earlier trial created a difficult comparison
Another pressure point was the apparent gap with earlier research.
A smaller study showed a 49% reduction in recurrence or death and a 59% reduction in distant metastasis or death, compared with 42% and 38%, respectively, in the larger trial.
However, “different patient populations” and “follow-up periods” mean these are not really direct comparisons.
The latest findings also contain nuance that headline percentages miss.
The companies said the treatment groups performed similarly during the first six months; a prespecified analysis showed stronger benefits afterward. Overall survival data remain immature.
That makes sweeping conclusions premature. The study supports a reduction in recurrence, but it has not yet established an overall survival benefit.
Moderna investors assessing durability, treatment timing, and eventual adoption still have major questions to resolve as follow-up continues.
What’s the next test for MRNA shares?
Moderna’s next challenge is turning clinical progress into an economically attractive product.
The company is preparing to seek US approval and anticipates a potential launch in 2027.
Because the therapy is tailored to each patient’s tumor, investors will need to assess manufacturing capacity, delivery times, reimbursement, and the cost of supplying treatment.
Strong efficacy alone cannot establish the margins or sales volumes the business will ultimately generate.
Friday’s decline therefore raises a practical valuation question: how much future success does MRNA stock already assume at about 50x sales?
Regulatory progress, launch economics and evidence from additional cancer trials could help answer it.
Until then, a positive melanoma study can strengthen Moderna’s scientific credentials while still leaving shareholders vulnerable to falling expectations.
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