Gilead Sciences Inc. Gilead Sciences develops and markets therapies to treat and prevent life-threatening infectious diseases, with the core of its portfolio focused on HIV and hepatitis B and C. Gilead's acquisition of Pharmasset brought rights to hepatitis C drug Sovaldi, which is also part of newer combination regimens that remain standards of care. Gilead is also growing its presence in the oncology market via acquisitions, led by CAR-T cell therapy Yescarta/Tecartus (from Kite) and breast and bladder cancer therapy Trodelvy (from Immunomedics).