Moderna and partner Merck & Co said on Monday their cancer vaccine in combination with blockbuster cancer therapy Keytruda improved survival and showed durable efficacy in a mid-stage study in patients with a deadly form of skin cancer.

Detailed data on Monday from the 157-patient trial showed that after two and a half years, melanoma patients that had received the cancer vaccine combination showed an overall survival rate of 96%, compared with 90.2% with Keytruda alone.

About 75% of the patients on the vaccine combination had recurrence-free survival, compared with 55.6% on Keytruda alone.

The latest data offered more evidence of the vaccine's durability, after a December report that showed a 49% reduction in the risk of recurrence or death among patients who were on the vaccine combination versus Keytruda alone, with a median follow-up of nearly three years.

Moderna and Merck's collaboration is one of the several in the industry that are combining powerful drugs to use the immune system for targeting cancer with the mRNA vaccine technology, which carries instructions for cells to make specific proteins.

Merck and Moderna, which have been collaborating since 2016, are also conducting a late-stage study of their vaccine and Keytruda combination.