** Shares of Regeneron REGN.O decline 11.3% to $619.70 premarket

** The drugmaker said late Friday its experimental drug combination did not show statistically significant improvement in survival without progression of a type of skin cancer in a late-stage study vs Merck's MRK.N Keytruda

** The trial was testing drug candidate fianlimab and approved-drug Libtayo as a first-line treatment for patients with unresectable locally advanced or metastatic melanoma

** Detailed results from the trial will be presented at an upcoming medical meeting - REGN

** Adds that another late-stage fianlimab trial is ongoing

** At least four brokerages cut their PTs on REGN

** Up to last close, stock had fallen 9.5% YTD