Altus ( ALTU) plunged 31% after the biotech announced delays in beginning Phase III clinical trials on two of its compounds in development.

The Cambridge, Mass., company said it now expects to "perform additional manufacturing development work" on its Altu-135 orally administered enzyme-replacement therapy. That trial is slated for patients with pancreatic insufficiency. The company said the delay was caused by the finding that "one of the three lots for Altu-135 produced using the Phase III manufacturing process showed lower activity for one enzyme."

Altus said a supplier of its Altu-238 long-acting, crystalline human growth hormone told the company of a delay in delivering certain equipment for the production of the compound. "Altus expects to use this time to develop and qualify additional assays prior to Phase III production of ALTU-238 to ensure process reproducibility and product consistency," Altus said.

"Altus does not believe these delays are related to its proprietary protein crystallization technology, but instead are related to the challenges of implementing appropriate manufacturing controls and analytical methods," the company said.

Shares dropped $5.37 late Monday to $12.