CHICAGO, May 23 (Reuters) - A jury in Chicago on

Thursday rejected an Illinois woman's claim that the now

discontinued heartburn drug Zantac caused her colon cancer, in

the first trial out of thousands of lawsuits making similar

allegations.

The jury in Cook County, Illinois circuit court agreed with

arguments from drugmakers GSK and Boehringer Ingelheim

that the plaintiff, 89-year-old Illinois resident Angela

Valadez, had not proven her colon cancer was at least in part

caused by her Zantac use.

Valadez had alleged that her cancer was a result of taking

over-the-counter Zantac and generic versions of it from 1995 to

2014. The lawsuits over the drug say its active ingredient,

ranitidine, under some conditions turns into a cancer-causing

substance called NDMA.

Attorneys for Valadez had asked the jury to award $640

million for her suffering. The judge rejected Valadez's request

to seek punitive damages during the trial, according to her

attorneys.