Israel's Teva Pharmaceutical Inc. said Friday it would discontinue a trial testing its drug for the treatment of chronic cluster headache, after an analysis showed that the drug was unlikely to meet the study's main goal.

Cluster headaches occur in cyclical patterns, or clusters, and are among the most painful types of headaches.

The drug, fremanezumab, is under review by the U.S. Food and Drug Administration for prevention of migraines in adults and the company hopes to launch the drug for the disorder as soon as mid-September.

Teva, which is counting on fremanezumab to help return to growth, also plans to continue testing the drug for the treatment of episodic cluster headaches.

"While we are disappointed with this outcome, we remain optimistic that fremanezumab could have clinical benefits in additional conditions, beyond migraine," said Tushar Shah, senior vice president, head of global specialty clinical development at Teva.

Teva's U.S.-listed shares fell 1.6 percent to $23.4 in premarket trading.