Three scientific advisers worked with Riordan to create the company: Peter Dervan of Caltech, Doug Melton of Harvard, and Harold M. Weintraub of the Fred Hutchinson Cancer Research Center, along with H. Dubose Montgomery, one of Menlo Ventures founders.

[13] The company's primary therapeutic focus was in antiviral medicines, a field that piqued Riordan's interest after he contracted dengue fever.

[14] Riordan recruited Donald Rumsfeld to join the board of directors in 1988,[15] followed by Benno C. Schmidt, Sr.,[citation needed] Gordon Moore,[15] and George P.

[8] Riordan later recalled that Gilead's first decade as a startup was an extremely stressful experience for him, as a young venture capitalist serving for the first time as the founder, chairman, and chief executive officer of his own biotech company.

[23] One reason for entering into the Tamiflu licensing agreement was that with only 350 employees, Gilead still did not yet have the capability to sell its drugs directly to overseas buyers.

[25] In 2002, Gilead changed its corporate strategy to focus exclusively on antivirals, and sold its cancer assets to OSI Pharmaceuticals for $200 million.

[7][15] The San Francisco Chronicle noted that by 2003, the Gilead corporate campus in Foster City had expanded to "seven low-slung sand-colored buildings around a tiny lake on which ducks happily paddle.

With two drugs in development (ambrisentan and darusentan), and one marketed product (Flolan) for pulmonary diseases, the acquisition of Myogen has solidified Gilead's position in this therapeutic arena.

Under an agreement with GlaxoSmithKline, Myogen marketed Flolan (epoprostenol sodium) in the United States for the treatment of primary pulmonary hypertension.

Additionally, Myogen was developing (in Phase 3 studies) darusentan,[35] also an endothelin receptor antagonist, for the potential treatment of resistant hypertension.

[48] The acquisition brings drug candidate CYT387, an orally-administered, once-daily, selective inhibitor of the Janus kinase (JAK) family, specifically JAK1 and JAK2, into Gilead's oncology pipeline.

[58] On May 9, 2019, the U.S. Department of Health and Human Services announced that Gilead Sciences will donate Truvada, the only drug approved to prevent infection with H.I.V., for free to 200,000 patients annually for 11 years.

HHS Secretary Alex Azar explained that the U.S. government will pay Gilead $200 per bottle for 30 pills for costs associated with getting the drug from factories into the eventual hands of patients.

[61][62][63] On April 7, 2020, Gilead completed acquisition of Forty Seven, Inc. for "$95.50 per share, net to the seller in cash, without interest, or approximately $4.9 billion in the aggregate.

"[64][65] In June 2020, Bloomberg reported that AstraZeneca Plc had made a preliminary approach to Gilead for a potential merger, worth almost $240 billion.

[69] In September 2020, Gilead announced it had reached a deal to acquire Immunomedics for $21 billion ($88 per share), gaining control of the cancer treatment Trodelvy (Sacituzumab govitecan-hziy) – a first-in-class Trop-2 antibody-drug conjugate.

[85] On July 11, 2014, the United States Senate Committee on Finance investigated Sovaldi's high price ($1,000 per pill; $84,000 for the full 12-week regimen).

Senators questioned the extent to which the market was operating "efficiently and rationally", and committee chairman Ron Wyden (D-Oregon) and ranking minority member Chuck Grassley (R-Iowa) wrote to CEO John C. Martin asking Gilead to justify the price for this drug.

[87] For poorer countries, Gilead licensed multiple companies to produce generic versions of Sovaldi; in India, a pill's price was as low as $4.29.

[100] Plaintiffs allege that Gilead suspended TAF in 2004 despite clear evidence indicating that TAF-based medications were safer than TDF, a compound whose long-term use was associated with adverse side effects such as nephrotoxicity and bone density loss.

Lawsuits allege that in the interim period, many HIV patients who continuously took Gilead's older TDF-based drugs suffered severe side effects, including nephrotoxicity.

[109][5] The committee's investigation, based in part on internal documents obtained from Gilead, revealed that the company had considered prices ranging from $50,000 to $115,000 per year, trying to strike a balance between revenue and predicted activist and public relations blowback, with little regard to research and development costs.

[6] In May 2019, Gilead announced it would donate enough Truvada to treat up to 200,000 patients annually for up to 11 years, the result of discussions with the Department of Health and Human Services under Trump.

[114] Walensky led a 2020 study that concluded the high costs of Descovy would on the whole negate any comparative advantage of prescribing it over a generic Truvada alternative.

Included in the licensing agreements were 'anti-diversion' provisions, designed to prevent the drug from being exported back to developed countries where the cheaper, generic alternatives were still unavailable.

)[120] Gilead required the Indian producers to screen patients to determine who could buy Sovaldi, which was criticized by Médecins Sans Frontières since it could lead to the exclusion of vulnerable groups like refugees and migrants from accessing the medicines.

[127] This designation is intended to encourage the development of drugs affecting fewer than 200,000 Americans by granting strengthened and extended legal monopoly rights to the manufacturer, along with waivers on taxes and government fees.

[128] Remdesivir became a candidate for treating COVID-19; at the time the status was granted, fewer than 200,000 Americans had COVID-19, but numbers were climbing rapidly as the COVID-19 pandemic reached the US, and crossing the threshold soon was considered inevitable.

[133] However, over 2020–22 with further clinical research, remdesivir had been approved for treatment of hospitalized people with COVID-19 in the United States, European Union, and multiple other countries.

[137] Veklury received approval from the US Food and Drug Administration (FDA) in October 2020 use in hospitalized adults and children 12 years and older for treatment of severe COVID-19 infections.