Gilead Sciences, HIV Antiretrovirals, and the Pursuit of Profit
Over the summer, a series of pharmaceutical product liability actions have been brought to California state courts against Gilead Sciences, Inc., a Bay Area-based pharmaceutical company that researches, develops, and commercializes antiviral drugs used to prevent and manage Human Immunodeficiency Virus-1 (HIV).
More than 50 patients treated with HIV antiretroviral drugs have filed a lawsuit against Gilead Sciences, claiming that the company placed profits before safety when it withheld from the market a safer and more effective antiretroviral than the one that it sold.
This story begins in the mid-1990s when Gilead Sciences acquired the exclusive rights to synthesize tenofovir, a compound that can prevent viral replication. Soon after, in 2001, Gilead Sciences began manufacturing and selling tenofovir disoproxil fumarate (TDF), a prodrug form of tenofovir.
But there was a catch. As a prodrug, TDF metabolizes throughout the body in a way that renders it unable to distinguish between cells infected with HIV and cells not infected with HIV. This means that even though some of the drug is activated by HIV-infected cells, the remainder of the drug sits in the gastrointestinal tract, liver, and blood supply, producing toxic effects on healthy cells throughout the body. So toxic, in fact, that patients have reported chronic kidney diseases, acute kidney failure, osteoporosis, and cancer.
Just as it was developing TDF, Gilead Sciences was also developing another prodrug form of tenofovir—tenofovir alafenamide fumarate (TAF). Unlike TDF drugs, TAF drugs only metabolize when they have been absorbed by cells affected by HIV, a process which leaves other vital organs unaffected.
So, then, why did Gilead Sciences quickly shelve its TAF project in 2004?
There is no clear answer yet. According to the petitioners of a lawsuit filed in July, the timing is curious. They claim that Gilead Sciences shelved TAF (a safer, more effective form of tenofovir) for fifteen years, all as part of a move to maximize the profits on their existing TDF patent before its expiration in 2015. The lawsuit continues, alleging that Gilead Sciences conducted studies demonstrating that TAF drugs were less likely to produce toxic effects for patients than their TDF counterparts. Still, it withheld the drug from the market until 2015, which enabled it to “extend its exclusivity on tenofovir and keep its HIV drugs branded and priced high.” Not only that, but it allowed Gilead Sciences to begin marketing its TAF-based drug to physicians as a safer and more effective alternative to TDF-based drugs.
Was TAF withheld from the market? Or was it abandoned in a laboratory? Does the answer render Gilead Sciences more or less responsible for the kidney and bone problems of its consumers? This is for a California state court in Santa Clara County to decide.
 Anna Schuessler. 2019. Patients File Suit Against Gilead for HIV Treatment Side Effects. The Daily Journal.