Piper Jaffray analyst Edward Tenthoff views Celgene's (CELG) acquisition of Receptos (RCPT) as good for Arena Pharmaceuticals (ARNA). Tenthoff views Arena as a "derivative call" on the deal with the company's APD334 already showing dose-dependent decreases in circulating lymphocyte counts. Arena will also initiate Phase II studies in ulcerative colitis and Crohn's disease this year, the analyst points out. Receptos' ozanimod is being studied in Phase III trials for relapsing multiple sclerosis and ulcerative colitis. Tenthoff reiterates an Overweight rating on Arena with a $7.50 price target. The company has a market capitalization around $1B and closed yesterday up 8c to $4.47