Citi stays bearish on Moderna after full melanoma vaccine data; shares extend slide

** Shares of drugmaker Moderna MRNA.O fall 6.4% to $187.25 after an 18% slide over the previous two sessions

** Citi maintains "sell/high risk" rating and $80 price target on the stock

** Brokerage says full data on Moderna's experimental cancer vaccine, intismeran, in melanoma skin cancer did not ease concerns around valuation and execution

** Citi says specialists viewed the data positively but not as a treatment that would fundamentally change melanoma care

** Citi analysts cite concerns around manufacturing timelines, patient screening hurdles, commercial adoption and whether results in melanoma can be replicated in other cancers

** Brokerage says expectations for upcoming kidney cancer data remain high and valuation already assumes success across multiple unproven factors

** Citi's price target implies about 60% downside to Moderna's Friday close

** The company and partner Merck MRK.N published detailed data from the late-stage melanoma trial after the results were leaked on an oncology website​‌

** Including session's move, stock up ~557% YTD