Moderna (MRNA.O) shares tumbled as much as nearly 25% intraday on Thursday; Merck (MRK.N) fell 3.7%. Data from the experimental cancer vaccine the two firms are developing appears to have been posted early on medical site Oncology Central and was subsequently removed; the results had been scheduled for presentation at the European Society for Medical Oncology (ESMO) meeting on Saturday. The briefly posted data suggested the vaccine, administered with Merck’s Keytruda, reduced the risk of melanom

Moderna (MRNA.O) shares tumbled as much as nearly 25% intraday on Thursday; Merck (MRK.N) fell 3.7%. Data from the experimental cancer vaccine the two firms are developing appears to have been posted early on medical site Oncology Central and was subsequently removed; the results had been scheduled for presentation at the European Society for Medical Oncology (ESMO) meeting on Saturday. The briefly posted data suggested the vaccine, administered with Merck’s Keytruda, reduced the risk of melanoma recurrence or death. Both companies had previously said the Phase III trial met its primary endpoint but have not published detailed results.