The drug, known generically as fremanezumab, competes with rival treatments from Eli Lilly & Co and Amgen Inc. Lilly in November received the U.S. Food and Drug Administration’s “breakthrough” status for its migraine drug Emgality in treating episodic cluster headaches. In a late-stage trial, three out of four patients treated with Lilly’s drug saw at least a 50 percent reduction in weekly cluster headaches. Teva’s decision could be positive for Lilly’s drug in differentiating it from its rivals, BMO Capital Markets analyst Alex Arfaei said.