A version of this article first appeared in CNBC's Healthy Returns newsletter, which brings the latest health-care news straight to your inbox. Subscribe here to receive future editions.The booming weight loss drug market has gained a new potential competitor. AbbVie said on Monday that it will pay up to 2.2billiontodevelopDanishdrugmakerGubra′sexperimentalobesitydrug,markingitslateforayintothesegment. Underthetermsofthedeal,thepharmaceuticalgiantwillpayGubra350 million upfront ...