Last week, US District Judge Richard Seeborg issued a summary judgment in favor of pharmaceutical giants Pfizer and Eli Lilly, over claims that Viagra and Cialis cause skin cancer.
In the ruling, Judge Seeborg rejected the opinions of three experts claiming that they failed to apply a Bradford Hill analysis to their findings, which requires nine factors to determine causation that include: the strength of the association, consistency, specificity, temporality, biological gradient or dose-response, biological plausibility, coherence with other scientific knowledge, experimental evidence, and analogy.
During a four-day hearing in October last year, the judge listened to expert witnesses from both parties but found that evidence provided by plaintiffs’ experts did not support a strong association or relied on smaller studies over the link between impotence drugs and skin cancer.
The recent summary judgment, dismissing all claims in the MDL, was issued in favor of the drug makers, following the decision on January 13 to exclude the general causation opinions offered by plaintiffs’ experts.
In 2016, the U.S. Food and Drug Administration placed Viagra and other erectile dysfunction drugs collectively known as phosphodiesterase type 5 inhibitors on its watch list of medications with possible safety issues.
The FDA action followed a 2014 report in the Journal of the American Medical Association (JAMA) that linked an increased risk of melanoma with Viagra use. Loeb's team, in 2015, published a detailed analysis in JAMA of the medical records of 20,000 men in Sweden that found no evidence that Viagra or similar medicines cause melanoma.
The drug makers were facing more than 1,000 lawsuits, consolidated into multidistrict litigation in San Fransisco. Each lawsuit was seeking billions of dollars in damages over cancer allegations.
