June 6 (Reuters) - Otsuka's experimental drug

for a type of kidney disease showed over 50% reduction in

protein in patients' urine in a late-stage trial, the

Japan-based company said on Friday.

Patients treated with the therapy, sibeprenlimab, achieved

a 51.2% reduction in proteinuria at nine months of treatment

when compared to placebo.

The company is seeking approval for the therapy, a

monoclonal antibody, to treat Immunoglobulin A Nephropathy

(IgAN), also known as Berger's disease, which causes abnormal

protein buildup in the kidneys and could eventually lead to the

organ's failure.

It was the largest IgAN trial to date, which consisted of

about 510 adult patients the company said.

The U.S. health regulator is set to decide on the marketing

application of the therapy by November 28.

Shares of rival Vera Therapeutics ( VERA ) fell over 31% in

premarket trading.

Vera's experimental drug, atacicept, reduced protein levels

in patients' urine by 46%, compared with a 7% reduction with a

placebo, meeting the main goal of the 428-patient late-stage

study, the company said on Monday.