* Calquence gets green light for mantle cell lymphoma
* Drug also being studied in range of other cancers
* FDA approval triggers $1.5 bln payment by AstraZeneca (Adds CEO comment, details on competition, sales forecasts)
LONDON, Oct 31 (Reuters) - AstraZeneca has won U.S. approval for a new blood cancer drug several months earlier than expected, boosting its oncology portfolio - and requiring it to pay $1.5 billion to shareholders in the biotech company that first discovered the medicine.
The U.S. Food and Drug Administration (FDA) said on Tuesday it approved Calquence, or acalabrutinib, as a treatment for adults with a rare type of blood cancer called mantle cell lymphoma who have received at least one prior therapy.
The British-based company had said it expected a U.S. approval decision by the first quarter of 2018, after the FDA granted an accelerated approval pathway.
Acalabrutinib is a cornerstone product for AstraZeneca in haematology and the U.S. approval marks its first entry into blood cancer treatment. Chief Executive Pascal Soriot said it was "a landmark moment for our company".
AstraZeneca acquired acalabrutinib when it bought a majority stake in Acerta Pharma in 2015. It paid $2.5 billion upfront at the time, with a further $1.5 billion due on first regulatory approval of the medicine.
Although AstraZeneca said in 2015 it believed acalabrutinib could eventually sell more than $5 billion a year, analysts have been more cautious, with consensus forecasts pointing to sales of $1.1 billion in 2023, according to Thomson Reuters data.
Acalabrutinib works in a similar way to Johnson & Johnson and AbbVie's Imbruvica. However, the new medicine's side effect and efficacy profile have the potential to make it a best-in-class product.
AstraZeneca's drug is also in development for the treatment of multiple B-cell malignancies and other blood cancers including chronic lymphocytic leukaemia, Waldenström macroglobulinaemia, follicular lymphoma, diffuse large B-cell lymphoma and multiple myeloma.
In addition, it is being studied as a monotherapy and in combination trials for solid tumours.
The drug is given as a 100 milligram capsule taken orally approximately every 12 hours. Common side effects include headache, diarrhea, bruising, fatigue, muscle pain and anemia.
AstraZeneca is relying heavily on new cancer drugs to revive its fortunes as it grapples with loss of patent protection on older medicines, like its best-selling cholesterol fighter Crestor.
Most investor attention is focused on its immuno-oncology medicines, especially in lung cancer, where it is conducting a range of clinical trials.
The company earlier on Tuesday announced it was starting a new pivotal lung cancer trial with to test its drug Imfinzi alongside Incyte's second-generation immunotherapy drug epacadostat. (Additional reporting by Tamara Mathias in Bengaluru; Editing by Savio D'Souza and Edmund Blair)