** Shares of drug developer Vera Therapeutics VERA.O fall 33.1% to $20.50 premarket

** Rival Otsuka's 4578.T experimental drug for a type of kidney disease showed over 50% reduction in protein in patient's urine in a late-stage trial, co says

** VERA's shares surged 60% on Monday after its experimental kidney disease drug, atacicept, helped significantly reduce harmful levels of proteins in the urine in a late-stage study

** Both companies are developing drugs to treat IgA nephropathy, which causes abnormal protein buildup in the kidneys and could eventually lead to the organ's failure

** Vera's drug atacicept reduced protein levels in patients' urine by 46%, compared with a 7% reduction with a placebo

** Up to last close, VERA down 27.6% YTD

(Reporting by Sneha S K)

((Sneha.SK@thomsonreuters.com))