Moderna's experimental cancer vaccine proved effective in a Phase 3 trial, yet the company's shares tumbled nearly 18%. The vaccine cut the risk of cancer recurrence and death by 42%, but that fell short of the 49% reduction seen in Phase 2, triggering a wave of selling.
Moderna and Merck released Phase 3 results on the 22nd for intismeran, a personalized messenger RNA (mRNA) cancer vaccine the two companies are developing jointly, according to Reuters and other outlets. Patients who received the vaccine together with Merck's immunotherapy Keytruda had a 42% lower risk of cancer recurrence or death than those treated with Keytruda alone. The figure came in below results from the Phase 2 trial, which involved a smaller group of patients.
The trial enrolled 1,137 patients with high-risk stage 2B to stage 4 melanoma whose tumors had been surgically removed. Patients were assigned in a 2-to-1 ratio to the combination group and the Keytruda-only group, with a median follow-up of 24.6 months. The hazard ratio for recurrence or death was 0.58, meaning the instantaneous risk of recurrence or death in the combination group was 58% of that in the group given Keytruda alone.
The results had originally been scheduled for presentation on the 24th at the European Society for Medical Oncology (ESMO) congress in Madrid. But Moderna, Merck and the society moved up the release after the trial data appeared on the medical news site Oncology Central and was then deleted. ESMO is investigating how its embargo rules were breached.
Moderna closed at $202.63 in New York on the same day, down 17.57% from the previous session. The stock was down more than 25% at one point during the day. Merck, its development partner, fell 1.8%. Moderna had surged 177% in a single day on Aug. 19, when news of the Phase 3 success first emerged. The stock continued to climb and hit a 52-week intraday high of $254.48 on the 21st of this month.
U.S. financial news outlet MarketWatch said the hazard ratio of 0.58 was in line with or slightly below Wall Street expectations. Evan Seigerman, an analyst at BMO Capital Markets, said the reduction in the risk of cancer recurrence and death was a meaningful result, adding that the share decline reflected expectations for the trial data that had run too high rather than any problem with the treatment's efficacy.