Shares of CymaBay Therapeutics Inc. /zigman2/quotes/201917619/composite CBAY +7.48% plummeted 43% in premarket trade Tuesday after the biotech said data from an ongoing Phase 2 trial showed patients with nonalcoholic steatohepatitis (NASH) who were treated with investigational drug seladelpar did not show significant reductions in liver fat when compared with those on a placebo. However, treatment with seladelpar did result in a reduction in biomarkers associated with liver injury, the company said. "While the reductions in liver fat were minimal, we remain encouraged by the significant improvements in biochemical markers of liver injury that we observed at week 12," said Pol Boudes, CymaBay's chief medical officer. "The 52-week liver biopsy data will allow us to understand whether the improvement in liver injury markers will translate into histological improvement. The observed improvement in markers of liver injury are consistent with the observed effects of seladelpar in PBC and further support the potential for seladelpar to improve liver health." In NASH, fat builds up in the liver, triggering inflammation and cell injury that can lead to serious complications like cirrhosis, or liver scarring. There have been several trial updates in the NASH space so far this year from companies like Gilead Sciences Inc. /zigman2/quotes/210293917/composite GILD +1.84% and Intercept Pharmaceuticals Inc. /zigman2/quotes/202434567/composite ICPT +5.36% , but they have not been promising, according to Jefferies health desk trader Jared Holz. "Investors have not been impressed with current data," he wrote in a note to clients Tuesday morning. Shares of CymaBay Therapeutics Inc. have gained 41% in the year to date through Monday, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +1.19% has gained 15%.