On Tuesday, a medical researcher testified that there is a possible link between two blockbuster erectile dysfunction (ED) drugs, Viagra and Cialis, and skin cancer.
Assistant Professor of Oncology at the Dana Farber Cancer Institute Dr. Rizwan Haq said, “There is a biologically plausible mechanism by which Sildenafil causes accelerated melanoma progression.” He testified his findings in court Tuesday based on his analysis of about 50 studies and concluded the drugs could cause melanoma.
Viagra (sildenafil) is manufactured by Pfizer, while Cialis (tadalafil) by Eli Lilly. These are extremely popular drugs when it comes to treating erectile dysfunction, or impotence, in men.
Dr. Haq testified his conclusions to US District Judge Richard Seeborg who will decide whether the science justifying the claims against the two pharma giants is strong enough to absolve a jury trial.
Lead Counsel of Pfizer and the chair of Williams and Connolly in Washington Joseph Petrosinelli has attempted to discredit Dr. Haq, stating that he is one of three lone researchers who claim that ED drugs cause skin cancer.
Petrosinelli told Judge Seeborg, “They are the only three people in the world who have said that.”
He argued that other medical researchers, drug regulatory bodies, and reputed medical organizations, including the American Academy of Dermatology, have not found any possible link between those ED medications and melanoma.
Responding to Petrosinelli’s comments, Judge Seeborg noted that no physicians have stepped forward to claim conclusively that sildenafil and tadalafil do not cause skin cancer.
The judge asked the Pfizer attorney, “Are you suggesting there’s a certain critical number I have to come to,” referring to the number of physicians who say that those drugs may cause skin cancer.
Petrosinelli said that “no professionals who did original research on this subject concluded that erectile dysfunction drugs contribute to melanoma. The only reason a weak association has been found is because men who take Viagra and Cialis for whatever reason are exposed to the sun more.”
Dr. Haq explained how Viagra and Cialis, which belong to the class of drugs phosphodiesterase type 5 (PDE5) inhibitors, stop the degradation of a substance called cyclic guanosine monophosphate (cGMP), which relaxes smooth muscles and dilates blood vessels to increase blood flow, treating ED.
The medical researcher said, “It’s pretty clear that PDE5 is present in melanoma cells.” The hearing will be continued through October 22.
