Pharma Giants Defeat Claims that Impotence Drugs Cause Skin Cancer

The Pfizer logo appears on a screen above its trading post on the floor of the New York Stock Exchange in 2016. (AP Photo/Richard Drew, File)

SAN FRANCISCO (CN) — Pharmaceutical giants Pfizer and Eli Lilly on Wednesday defeated a multidistrict class action seeking billions of dollars in damages over claims that Viagra and Cialis cause skin cancer.

U.S. District Judge Richard Seeborg issued summary judgment in favor of the drug makers, finding the plaintiffs had no path forward following his Jan. 13 decision limiting what evidence could be presented at trial. In that ruling, Seeborg rejected the opinions of three experts who testified about a causal link between the erectile dysfunction drugs and melanoma.

In light of that decision, Seeborg wrote in a ruling Wednesday that Pfizer and Eli Lilly “are entitled to and hereby are granted summary judgment in their favor as to all of plaintiffs’ claims.”

The two drug makers were facing potentially billions of dollars in damages from more than 1,000 lawsuits consolidated into a multidistrict case in San Francisco.

During a four-day hearing in October last year, Seeborg heard testimony from plaintiffs’ experts and defense experts on whether active ingredients in each drug can increase the risk of skin cancer.

One plaintiffs’ expert, dermatologist Rehana Ahmed-Saucedo of the University of Minnesota, concluded based on her review of multiple scientific studies that there is an association between phosphodiesterase type 5 inhibitors in Viagra and Cialis and melanoma.

Seeborg found she failed to account for the fact that no studies she reviewed “established a relationship between the amount of exposure to PDE5 inhibitors and melanoma progression.”

Seeborg concluded that another plaintiffs’ expert, internal medicine specialist Sonal Singh of the University of Massachusetts, relied too heavily on “one of the smallest studies” that found a relationship between the drug’s active ingredient and skin cancer progression, even though such results were found in no other study.

The judge also deemed the opinion of a third expert, epidemiologist Feng Liu-Smith of the University of California, Irvine, unreliable because she “conflate[d] strength of association with consistency, as a means of downplaying the undeniable fact that the evidence does not support a finding of a strong association.”

Seeborg found each expert also failed to properly apply a Bradford Hill analysis to their findings, which requires using nine factors to determine causation. The nine factors include strength of the association; consistency; specificity; temporality; biological gradient or dose response; biological plausibility; coherence with other scientific knowledge; experimental evidence and analogy.

“They have not reliably applied a Bradford Hill analysis to make the requisite leap from correlation to causation,” Seeborg wrote in his Jan. 13 decision.

The judge further noted that outside of this litigation, no known scientist or researcher has interpreted existing studies in a way that supports their theory: that the active ingredients in Viagra and Cialis increase one’s risk of developing skin cancer.

“Despite substantial research on the issue over many years, plaintiffs’ experts apparently stand alone,” Seeborg wrote.

A Pfizer spokesperson applauded Seeborg’s ruling.

“Pfizer is pleased that the court has entered summary judgment in the company’s favor, dismissing all claims in this MDL, following the decision in January to exclude the general causation opinions offered by plaintiffs’ experts. Pfizer stands behind Viagra and maintains there is no reliable scientific evidence it causes the injuries alleged in this litigation,” the spokesperson said in a statement.

Eli Lilly and plaintiffs’ attorney Ernest Cory of Cory Watson in Birmingham, Alabama, did not immediately return emails and phone calls requesting comment.

Approved by the FDA in March 1998, Pfizer’s Viagra has earned the company tens of billions of dollars since its introduction to the market. Viagra earned more than $2 billion in annual sales in 2008. Pfizer lost its exclusive right to sell Viagra in December 2017 and cheaper generic versions are now available.

Eli Lilly’s Cialis was approved to treat erectile dysfunction in the United States in 2003. Cialis earned $597 million in 2017, one year before generic versions of the drug hit the market.

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