A California judge has thwarted GlaxoSmithKline’s (GSK) attempt to prevent plaintiff expert testimony that shows an association between Zantac and several types of cancer, allowing a lawsuit by a California resident, who claims he developed bladder cancer because of the discontinued heartburn drug, to move forward in a state court in July, Reuters reports

Judge Evelio Grillo’s ruling was made despite a December 2022 ruling by the judge overseeing all federal Zantac lawsuits in multidistrict litigation (MDL)—Judge Robin Rosenberg—that dismissed approximately 50,000 federal Zantac claims. 

Judge Rosenberg had ruled that plaintiffs’ lawyers failed to present credible scientific evidence, but her decision does not apply to Zantac lawsuits filed in state courts. Overall, manufacturers of Zantac had faced over 100,000 lawsuits prior to Judge Rosenberg’s ruling. 

GSK maintains that 13 epidemiological studies featuring human data have concluded that ranitidine, the main active ingredient in Zantac, show that there is no convincing evidence that the drug causes cancer, Seeking Alpha reports.

Zantac was pulled from the market in 2020 after testing revealed that ranitidine becomes chemically unstable when stored for a long time at above room temperature, transforming into a potentially-carcinogenic compound, N-Nitrosodimethylamine (NDMA). The FDA daily safe limit for NDMA is 96 parts per million (PPM). Testing had revealed that some lots of Zantac contained as much as 3 million PPM. 

Judge Grillo’s approval of expert testimony means that the case of plaintiff James Goetz will proceed, making his case the first Zantac lawsuit to start at trial. Goetz’s case had been set to begin Feb. 27 but was delayed until July 24 so that Judge Grillo could rule on whether to allow expert testimony

An attorney for Goetz issued a statement per Reuters, saying, “Our client will now have his day in court, and we look forward to sharing the evidence with the jury that GSK has known for decades that Zantac contains staggering amounts of a proven carcinogen.” 

GSK was the first manufacturer of Zantac, bringing the drug to market in 1983. In December 2022, a different California Zantac trial was settled between the plaintiff and other manufacturers of Zantac, including Sanofi and Pfizer. GSK did not settle with the plaintiff. 

According to Seeking Alpha, in 1982, one year before Zantac came to market, GSK’s own research showed that ranitidine could degrade into NDMA.