(Adds tax, forecast details, company comment; updates shares)
Jan 8 (Reuters) - Celgene Corp, which has announced a deal to buy Impact Biomedicines, on Monday forecast 2018 total revenue that fell short of analysts' estimates, sending the U.S. biotech company's shares down 2 percent.
Celgene, which left its long-range 2020 forecast unchanged, said it expects 2018 full-year revenue of $14.4 billion to $14.8 billion. Analysts' on average were estimating revenue of $14.83 billion, according to Thomson Reuters I/B/E/S.
While headlines suggested the Impact deal announced on Sunday could cost up to $7 billion, Celgene said the only certain cost was the upfront payment of $1.1 billion, with all other payments contingent on approval and major sales milestones for fedratinib, a late stage drug for myelofibrosis.
With the addition of fedratinib, Celgene said at the JP Morgan Healthcare Conference in San Francisco that it will have 10 late-stage medicines with $1 billion to multibillion-dollar potential that could add more than $15 billion in peak revenue through 2030 as it girds for the eventual loss of patent exclusivity on its flagship blood cancer drug Revlimid.
Meanwhile, Revlimid continues to grow. Celgene forecast about $9.4 billion for 2018 Revlimid sales, or 15 percent growth.
Celgene also has partnerships with companies developing potentially transformational cancer therapies, including bluebird bio, Juno Therapeutics and Agios Therapeutics.
Despite multiple collaborations and a robust developmental pipeline, Chief Executive Mark Alles told the conference the company intends to invest heavily in research and business development in 2018.
He said U.S. tax law changes would enable Celgene to access 60 percent of its operational cash flow to deploy as it sees fit, overseas money that previously would have been subject to heavy taxation if it was used in the United States.
The company estimated its one-time transition tax under new rules would be between $800 million and $1.3 billion and expects to be able to announce the actual cost later this month.
Celgene forecast 2018 adjusted earnings to be in the range of $8.70 to $8.90 per share, a midpoint above the average analysts' estimate of $8.71 per share.
The company reiterated its 2020 forecast for revenue of $19 billion to $20 billion, with adjusted earnings to exceed $12.50 per share.
For the 2017 fourth quarter, Celgene expects total revenue of $3.48 billion, slightly higher than the average estimate of $3.46 billion.
Celgene shares were down $2.04, or 1.9 percent in early-afternoon trading at $102.94. (Reporting by Bill Berkrot in New York, Additional reporting by Akankshita Mukhopadhyay in Bengaluru; Editing by Saumyadeb Chakrabarty and Tom Brown)