Moderna stock plunges after cancer vaccine data leak

Moderna shares fell as much as 25 per cent on Thursday after partial results from its personalized melanoma vaccine with Merck leaked on social media, even though the full data, released hours later, showed the shot cut the risk of the cancer returning or death by 42 per cent, CNBC and BioPharma Dive reported.

The vaccine, intismeran autogene, was tested with Merck’s immunotherapy Keytruda in patients whose advanced melanoma had been surgically removed. Compared with Keytruda alone, the combination lowered the risk of recurrence or death by 42 per cent after a median of 24.6 months, according to the published results. It also cut the risk of the cancer spreading to distant parts of the body, or death, by 38 per cent.

About 82 per cent of patients who got the vaccine with Keytruda were alive without their melanoma returning two years later, compared with 70 per cent on Keytruda alone, CNBC reported. The companies said it is too early to say whether the treatment helps patients live longer overall.

Screenshots of the findings appeared online Thursday, which prompted the European Society for Medical Oncology to release the study details ahead of its presentation at the society’s meeting this weekend, BioPharma Dive reported. Merck shares fell about one per cent.

Analysts said the drop reflected sky-high expectations more than weak results. Moderna’s stock had risen more than 530 per cent this year before Thursday, according to CNBC, and investors had been looking for a 40 to 50 per cent reduction in risk. William Blair analyst Myles Minter called it a “sell-the-news reaction,” while RBC Capital Markets analyst Trung Huynh said the results were at the low end of expectations.

“This is a huge development for our patients,” Dr. Hussein Tawbi, a melanoma specialist at the University of Texas MD Anderson Cancer Center and an investigator in the trial, told CNBC.

The shot is built for each patient. It is designed from mutations in the person’s own tumour so the immune system learns to recognize those cancer markers. Moderna chief executive Stéphane Bancel told CNBC the company is finishing a filing to seek full regulatory approval next year. Merck and Moderna are also testing the approach in lung, bladder and kidney cancer.

The Thursday sell-off came on a weak day for markets: the TSX closed down 351 points as tech stocks slid. For more on vaccines in Canada, see our guide to the HPV vaccine, which helps prevent several cancers, by province.

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Sources: CNBC; BioPharma Dive.