Arena Pharmaceuticals watched its stock rocket more than 75% after APD334, its experimental drug for autoimmune disorders, showed strong promise in Phase II trials, slingshotting its development into Phase II.

Top-line results from a Phase Ib trial of the oral drug showed a dose-dependent effect on lymphocyte count lowering in blood, with mean falls from baseline of up to 69%.

Also, safety signals are looking good at this stage, with no clinically significant safety findings with respect to heart rate or rhythm or pulmonary function observed, nor elevations in liver enzyme tests, the San Diego-based firm said.

“Based on these impressive results, we plan to expedite APD334 into Phase II clinical trials for ulcerative colitis and Crohn's disease,” noted Jack Lief, Arena's president and chief executive.