Shares of Aeglea Bio Therapeutics Inc (NASDAQ: AGLE) were slumping Tuesday following the release of data from an early-to-mid- stage trial of its lead product candidate pegzilarginase for treating Arginase 1 deficiency, or ARG1-D. ARG1-D is a debilitating urea cycle disorder caused by deficiency of a key arginine metabolizing enzyme, leading to neurological abnormalities, hyperammonemia and early mortality. Wells Fargo Securities downgraded shares of Aeglea from Outperform to Market Perform following the data release.