The largest US health insurer, Aetna, has negotiated a discount for Gilead Sciences' hepatitis C treatment regime and said it plans to offer this as a preferred choice for its nearly 11 million commercial customers.

Aetna and other US insurers have resisted the high price of hepatitis C treatments.

Days after the Federal Drug Administration (FDA) approved AbbVie's Viekira Pak on Dec. 19 last year, the country's largest pharmacy benefit manager, Express Scripts, said it had negotiated a cheaper price.

In most cases, Express said it would no longer reimburse Gilead's Sovaldi - which costs $84,000 for the 12-week course of therapy - for patients who have the genotype 1 form of the disease (70% of US patients). This, it said, was unaffordable.

Gilead's latest Hepatitis treatment, Harvoni, combines Sovaldi with another drug. The one-pill, once-a-day treatment, which lists at $94,500 for 12 weeks, is claimed to boast cure rates well above 90%.

CVS Health Corp, one of the largest US managers of drug benefits, said it would give preferred status to the Gilead hepatitis C treatments and cover the AbbVie drug only as an exception.