Moderna stock falls as much as 25% on Thursday after a partial leak of results from a high-profile personalized cancer vaccine developed with Merck, even as the full data released later in the day showed meaningful clinical benefits relative to expectations.
The vaccine, called intismeran autogene, combined with Merck’s immunotherapy Keytruda, lowered the risk of melanoma recurrence or death by 42% compared with Keytruda alone, according to the companies. The combination also cut the risk of distant metastasis or death by 38% versus the immunotherapy on its own.
Roughly 82% of patients who received the personalized shot alongside Keytruda were alive without their melanoma returning at two years, compared with 70% among those treated with Keytruda alone, the companies reported.
Dr. Hussein Tawbi of the University of Texas MD Anderson Cancer Center, a trial investigator, called the results a major advance for patients. He also noted the added benefit came with milder side effects, including injection-site pain, compared with many cancer treatments.
The detailed phase 3 findings are slated for presentation at the European Society for Medical Oncology conference this weekend.
Merck Research Laboratories President Dr. Dean Li said adding a therapy to an already effective drug such as Keytruda can make it harder to show further gains, but he said the data demonstrate clear additional benefit. A separate analysis after the six-month vaccination period indicated a 58% reduction in the risk of recurrence or death. The companies cautioned it is too early to determine an overall survival advantage.
Moderna stock falls despite positive melanoma data
Analysts said investor expectations were elevated going into the release. Several noted the overall strength of the results following the leak.
“We assert this relative reduction in recurrence/death is clinically meaningful,” BMO Capital Markets analyst Evan Seigerman wrote in a note, adding that the sharp stock reaction likely reflected inflated expectations rather than shortcomings in the combination’s efficacy.
Oncologists and investors view the targeted vaccine approach as a potential breakthrough that could be expanded to other cancers. Merck and Moderna are running additional studies in non-small cell lung cancer, bladder cancer, and renal cell carcinoma.
Li said more evidence will be needed to show consistent benefit across tumor types.
The personalized vaccine is designed to match each patient’s unique tumor mutations, training the immune system to recognize those markers. Pairing the tailored response with Keytruda aims to help the body attack tumors more effectively.
The program could become a key commercial pillar for Moderna beyond its vaccines for Covid-19, influenza, and respiratory syncytial virus.
UBS analysts described the dataset as strong and said it supports confidence in trials under way in kidney and bladder cancers. They suggested the share move may have stemmed more from outsized expectations than from the data itself.
Moderna shares had surged more than 530% year to date as of Thursday afternoon before the drop. Merck shares fell about 1% Thursday and are up nearly 41% this year.
Because the therapy is individualized, manufacturing currently takes about six weeks. Merck Chief Executive Robert Davis said last week the company believes it can shorten that timeline, which could broaden access and speed delivery to patients.