Sunovion’s investigational COPD therapy SUN-101 (glycopyrrolate) was declined marketing approval by the FDA.

Sunovion put out a short statement saying only that regulators had issued a complete response letter for SUN-101 (dubbed glycopyrrolate, which is used with an experimental nebulizer), its top late-stage therapy. The Marlborough, MA-based biotech added that regulators were not demanding any new trials and that execs would work with the FDA on moving forward.

The twice-daily therapy aimed at becoming the first nebulized long-acting muscarinic antagonist for COPD after the company claimed back-to-back successes in Phase III — though their latest update on the data didn’t include key results on trough FEV1.