** AstraZeneca top FTSE 100 gainer, up 0.6%in sharply lower market, after Jefferies calls outmultibillion-dollar potential of durvalumab plus tremelimumabcombination immunotherapy in lung cancer
** Price target upgraded to £58 a share from £54
** Broker (4 stars for recommendation accuracy on AZN, perStarMine) sees up to 39% upside for shares if closely watchedMYSTIC clinical trial hits its goal vs 10% downside if it fails.Results from MYSTIC expected any time from February 2017
** Success could drive peak annual sales opportunity fordurvalumab and tremelimumab of around $7.9 bln in non-small celllung cancer (NSCLC), with more potentially from othercombinations and adjuvant NSCLC, Jefferies says