Spyre Therapeutics will not prioritize the use of its SPY072 drug candidate as a monotherapy to treat rheumatoid arthritis, saying that results from a phase 2 trial did not meet the company's threshold.

Shares of the biotechnology company fell on the news, losing 13% in after-hours trading to $93.50.

A substudy of the drug to treat rheumatoid arthritis, part of a broader phase 2 study focusing on rheumatic diseases, showed that high and low doses both had statistically significant benefits over a placebo on certain endpoints, Spyre said. The low dose demonstrated a statistically significant benefit on the study's primary endpoint, the company added.

But the magnitude of the results missed the company's targets, it said.

"The results provide proof-of-mechanism for TL1A in RA and support its potential in other autoimmune diseases and as a combination component, but did not meet the Company's internal bar to prioritize advancement of SPY072 in RA," the company said. SPY072 is designed to inhibit TL1A proteins.