Should pharma talk about drugs that can be repurposed?
In 2015 researchers learned that Pfizer’s rheumatoid arthritis therapy, Enbrel, a powerful anti-inflammatory drug, seemed to cut the risk of Alzheimer’s disease by 64 percent. Derived from analyzing hundreds of thousands of insurance claims, the startling results led people in Pfizer’s division of inflammation and immunology to encourage the pharma giant to conduct a clinical trial on thousands of patients. Estimating that conducting a massive clinical trial to verify the results would cost $80 million, Pfizer declined to do so.
“Enbrel could potentially safely prevent, treat and slow progression of Alzheimer’s disease,’’ according to a document discovered by the Washington Post. The PowerPoint slide show was created for review by an internal Pfizer committee in February 2018. Pfizer said that it decided during three years of internal reviews that Enbrel “did not show promise for Alzheimer’s prevention because the drug does not directly reach brain tissue,” according to a June 4, 2019, article in the Washington Post by Christopher Rowland. The company thought the clinical trial would not provide good results and that the repurposing did not meet its “rigorous scientific standards.’’ Spokesman Ed Harnaga claimed that science was the reason that the company did not pursue the idea of moving forward.
While it did not publish the results, Pfizer did share the data privately with at least one prominent scientist. With all of the frustration of trying to find a cure for Alzheimer’s, some scientists think that Pfizer should have made its findings public.
Rudolph E. Tanzi, a leading Alzheimer’s researcher and professor at Harvard Medical School and Massachusetts General Hospital, said, “Of course they should. Why not?’’ Keenan Walker, an assistant professor of medicine at Johns Hopkins who is studying how inflammation contributes to Alzheimer’s, added, “It would benefit the scientific community to have that data out there. Whether it was positive data or negative data, it gives us more information to make better informed decisions.’’
While internal discussions about repurposing drugs often take place behind closed doors, such decisions can have an impact well beyond the company involved. As the Enbrel discussion ended in 2018, Pfizer was abandoning Alzheimer’s research, closing its neurology division and laying off 300 employees.
At the same time, Enbrel has come to the end of its patent life, a 20-year period of exclusivity when a brand manufacturer reaps monopoly profits from a drug. Generic competition is cutting profits, reducing financial incentives to do further research into Enbrel and comparable drugs. Researchers previously supported by Pfizer for Enbrel research into Alzheimer’s that proved inconclusive are “frustrated,” believing that Pfizer and other companies do not want to invest heavily in further research when their markets could be undermined by generic competition.
While various ethicists have weighed in on the question of whether Pfizer should have divulged the potential for a clinical trial anyway, the company said it hesitated to do so, because Enbrel only has a limited effect on the brain. Pfizer claimed that the Enbrel molecule is too large to pass through the “blood-brain barrier’’ and directly target TNF-a in brain tissue. However, some Alzheimer’s researchers think that inflammation outside the brain, known as peripheral inflammation, influences inflammation within the brain.