Data breach causes Moderna (MRNA.US) to plunge 25%: personalized vaccine expectations fall short

According to Woofun AI, Moderna (MRNA.US) shares suffered a major drop on Thursday, falling 25% in a single day. This sharp volatility was not due to failed clinical data, but rather because some key results of the Intismeran autogene vaccine were accidentally leaked before official release, causing the market to price in the good news early and leading to subsequent profit-taking.

Despite the single-day plunge, the stock's cumulative gain in 2026 still exceeds 530%, demonstrating long-term optimism about funding in the field of personalized cancer therapy.

Woofun AI compiled data showing that this personalized vaccine, when used in combination with Merck’s (MRK.US) immunotherapy Keytruda, can reduce the risk of melanoma recurrence or death by 42%, and lower the risk of distant metastasis or death by 38%. Among patients receiving combination therapy, 82% remained relapse-free and alive two years later, compared to 70% in the group that received Keytruda alone.

Despite these impressive results, BMO Capital Markets (BMO.US) analyst Evan Seigerman pointed out that the price drop reflects previously excessive market expectations rather than inefficacy of the therapy; UBS (UBS.US) analysts also believe the trial results are excellent, and that the market’s reaction is mainly due to expectations being realized. It is noteworthy that Merck's share price fell by only about 1%, but its gain since 2026 is close to 41%, showing the stability of large pharmaceutical companies in the face of such news.

However, commercialization still faces significant challenges. Merck Research Laboratories president Dean Li admitted that the current trials are limited to melanoma and further validation is needed for its efficacy in other tumor types such as lung, bladder, and kidney cancers. The production process is even more of a bottleneck, as preparing each personalized vaccine dose takes six weeks and relies heavily on tumor gene sequencing technologies. Merck CEO Robert Davis stated that the company is committed to shortening this waiting time in order to accelerate patient benefits. The complete phase three trial results will be published this weekend at the European Society for Medical Oncology meeting, where more comprehensive survival data will be provided.

For the industry as a whole, the next core challenge is whether personalized medicine can be rapidly scaled up to meet investors’ high expectations. If Moderna succeeds in replicating its success across multiple cancer types, its product line will no longer be limited to COVID-19, flu, and respiratory syncytial virus vaccines, thereby establishing its long-term commercial value in the field of tumor immunotherapy.