Oct 20 (Reuters) - The U.S. Congressional Budget Office

said on Monday that new exemptions to drug price negotiations

for several blockbuster cancer medicines under President Trump's

One Big Beautiful Bill Act will cost the government up to $6

billion more over the next decade.

The new estimate reflects updated information about the

eligibility of Johnson & Johnson's ( JNJ ) Darzalex, Merck's ( MRK )

Keytruda and Bristol Myers' Opdivo for price

negotiation, the Congress' nonpartisan analyst said.

The act - this year's budget reconciliation bill - delays or

exempts drugs from the program if they have multiple

rare-disease designations or gain approval for non-orphan uses.

Previously, only drugs with a single rare-disease designation

were excluded.

In July 2025, the CBO estimated that the cost of the

change to the exemption would be $4.9 billion through 2034.

Including the additional drugs, the CBO said the estimated cost

would be $6.7 billion to $10.9 billion, depending on how the

government decides to treat new formulations of the drugs.

The Inflation Reduction Act, signed into law in 2022,

allowed Medicare to negotiate prices for some of the most costly

drugs that the program covers for 66 million people. The CBO had

estimated that the drug negotiation provisions in the Inflation

Reduction Act would save $98.5 billion over its first 10 years

(2022-2031).

The agency also noted that its estimate does not yet

incorporate new U.S. Centers for Medicare & Medicaid Services'

guidance issued in September, which changes how Medicare

Advantage spending is included in drug rankings for future

negotiations.