Lawsuits Over Viagra, Cialis Melanoma Risk Stayed 60 Days Following Exclusion of Plaintiffs’ Expert Witnesses

The U.S. District Judge presiding over all federal Viagra lawsuits and Cialis lawsuits has issued a stay on all proceedings in the litigation, after an order was issued last month that excludes plaintiffs expert witness testimony about the melanoma risk associated with the erectile dysfunction drugs, which may effectively end the active litigation.

There are currently about 1,000 product liability lawsuits pending against manufacturers of the widely marketed drugs, each raising similar claims that consumers and the medical community were not adequately warned that side effects of Viagra and Cialis may result in the development of melanoma, a severe and often life-threatening form of skin cancer.

Given similar questions of fact and law raised in complaints filed throughout the federal court system, the litigation has been centralized before U.S. District Judge Richard Seeborg in the Northern District of California as part of a multidistrict litigation (MDL), which was designed to reduce duplicative discovery into common issues in the cases, avoid conflicting pretrial rulings from different Courts and to serve the convenience of the parties, witnesses and the judicial system.

As part of the coordinated pretrial proceedings, Judge Seeborg held a series of Daubert hearings, at which time the Court heard testimony from proposed experts about the link between melanoma and Viagra or Cialis use, to gauge whether the opinions were sufficiently reliable to allow the cases to proceed to trial.

In an order (PDF) issued on January 13, Judge Seeborg determined that all of the proposed plaintiffs’ expert witnesses on general causation should be excluded, finding that the analysis for each of the three experts was “unduly results-driven,” which leaves plaintiffs without sufficient support for their claims.

“Plaintiffs insist that as the research has unfolded—from the earliest laboratory studies suggesting a possible biological mechanism by which PDE5 inhibitors might contribute to melanoma progression through an ever-increasing number of epidemiological studies and metastudies finding an association—it has become clear that ‘the science is heading towards causation’,” the judge noted in the order. “They have failed to show, however, how the evidence supports that characterization.”

In a separate order (PDF) issued on January 31, Judge Seeborg issued a stay on all further proceedings and deadlines for 60 days, and directed the parties to file a joint statement by April 3, 2020, which outlines their respective views as to what steps should follow in the litigation.

Melanoma Side Effects of Viagra and Cialis

Viagra (sildenafil citrate) was introduced by Pfizer in 1998, and it has become one of the most widely recognized brand-name medications on the market in the United States, used by millions of men to treat impotence and sexual dysfunction, including the inability to develop or maintain an erection.

Cialis (tadalafil) is a similar erectile dysfunction drug introduced in 2003, which also become a blockbuster treatment amid aggressive direct-to-consumer advertisements.

Although the drugs are widely prescribed and believed to be safe, recent studies suggest that Viagra and Cialis may reduce the body’s ability to resist the spread of melanoma. Plaintiffs maintain that if they had been warned about the risk, they may have detected the cancer earlier or avoided a diagnosis by avoiding the drugs.

The Viagra melanoma cases began to emerge after a study was published in the medical journal JAMA Internal Medicine in April 2014, in which researchers from Harvard Medical School found that men who took Viagra were 84% more likely to be diagnosed with melanoma than men who do not use the drug.

Plaintiffs allege that Pfizer and Eli Lilly knew or should have known about the melanoma skin cancer risk for years, indicating that studies published as early as 2011 suggested that the erectile dysfunction drug may promote melanoma cell invasion.

If the parties fail to reach a settlement or other resolution for the litigation, it is likely that the court will consider motions for summary judgment on behalf of the drug makers, and the plaintiffs are expected to appeal the rulings to establish that the expert witness testimony is sufficiently reliable under the federal Daubert standard to allow the cases to continue.