Rigel Pharmaceuticals Inc. (RIGL) will know whether or not its oral drug candidate Tavalisse, proposed for the treatment of adult patients with chronic immune thrombocytopenia, gets the FDA nod on April 17, 2018.Tavalisse, whose chemical name is Fostamatinib disodium, inhibits SYK kinase, a key signaling member in the immune process that leads to platelet destruction in immune thrombocytopenia (ITP).According to market research firm GlobalData, the ITP market across the seven major countries of the U.S., France, Germany, Italy, Spain, the UK, and Japan, is projected to grow from $928 million in 2015 to $985 million by 2025.If approved, analysts expect Tavalisse to rake in peak sales of $360 million.RIGL closed Tuesday’s (Mar.27) trading at $3.77, up 0.53%.