Gilead Statement on New York Times’ Story on TDF and TAF Development for HIV

Foster City, Calif., July 22, 2023 – Gilead Sciences provided the following statement pre-publication to the reporters for the New York Times in response to their questions before their recently published article on TDF and TAF medicines. The article is misleading and mischaracterizes Gilead’s actions and the development history of these medicines, both of which remain approved by the FDA as safe and effective HIV treatment and prevention options.

  • Gilead’s research and development decisions have always been, and continue to be, guided by our focus on delivering safe and effective medicines for the people who prescribe and use them. Both TDF- and TAF-containing medicines have been approved by FDA as safe and effective treatment and prevention options for healthcare providers to meet the specific needs of people living with HIV. These medicines continue to successfully treat and prevent HIV in millions of people.

  • Gilead made the decision to discontinue TAF development in 2004, when TDF was the standard of care, and its safety and effectiveness for long-term use was established by years of human studies and real-world experience. At that time, the data did not show that TAF was sufficiently different from TDF in terms of effectiveness, safety, and tolerability to support its continued development.

  • TAF did not replace TDF, and it is inaccurate to say that the decision to stop TAF’s development was based on patents. As always, Gilead continues working toward ending the HIV epidemic worldwide through our scientific innovation and attention to patient needs as well as our health equity efforts. The claims and allegations in this litigation are meritless.

We also want to share the following additional background in response to the New York Times article:

  • The documents cherry-picked by the New York Times—and relied upon by the plaintiffs’ lawyers in the pending products liability litigation related to TDF and TAF—are part of the examination drug companies do to evaluate different scenarios, based on different hypothetical assumptions, in the drug development process. None of the development scenarios cited in the New York Times article were followed or put into action, and the conclusions being drawn from the existence of these documents are simply inaccurate.

  • In 2004, in response to the input of the FDA, doctors, and patients, the company focused on developing TDF in combination with other medicines, and, in particular, to develop single pill treatment options containing TDF.  The subsequent development of single tablet regimens was called a “watershed in HIV treatment” by the FDA as this reduction in pill burden was critical to increase patient adherence and to avoid developing resistance to the treatments.

  • As noted in Gilead’s statement to the New York Times, by 2004, TDF’s safety and effectiveness was established by years of human studies and real-world experience, including a three-year clinical (human) study demonstrating that TDF was safe and effective for long-term use. By contrast, as of October 2004, when Gilead stopped TAF development, the long-term safety of TAF was unknown and impossible to predict, and would require extensive additional studies, including Phase III human trials.

  • Gilead started to study TAF in 2010 because there was a shift in patient needs. It took five more years of clinical trials to demonstrate that TAF was safe and effective at treating HIV.

About Gilead Sciences
Gilead Sciences, Inc. is a biopharmaceutical company that has pursued and achieved breakthroughs in medicine for more than three decades, with the goal of creating a healthier world for all people. The company is committed to advancing innovative medicines to prevent and treat life-threatening diseases, including HIV, viral hepatitis, COVID-19, and cancer. Gilead operates in more than 35 countries worldwide, with headquarters in Foster City, California.


For more information about Gilead, please visit the company’s website at, follow Gilead on Twitter (@Gilead Sciences) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.