A $1,000-per-pill drug that insurers are reluctant to pay for has quickly become the treatment of choice for a liver-wasting viral disease that affects more than 3 million Americans.
According to new research, prescriptions for Sovaldi have eclipsed all other hepatitis C pills combined in less than six months.
The promise of a real cure, with fewer nasty side effects, is enticing thousands of patients to get treated.
It's by far the strongest launch of any similar drug.
But Sovaldi's clinical and commercial successes have triggered scrutiny for manufacturer Gilead Sciences Inc., based in California.
Two senior U.S. senators are raising questions about documents suggesting that drug developers initially considered a much lower price.
Gilead recently reported its profits more than quadrupled in the second three months of this year.