(Corrects spelling of analyst name in paragraph 3 to Syed)

By Deena Beasley

(Reuters) -Amgen ( AMGN ) on Tuesday reported quarterly financial results that beat Wall Street expectations, and raised its full-year outlook, as 12% sales growth offset expenses related to experimental weight-loss drug MariTide and a higher tax rate.

The California-based biotech company's third-quarter revenue also rose 12% from a year earlier to $9.56 billion, which was ahead of analysts' estimates of $8.97 billion, according to LSEG data. Adjusted earnings per share increased 1% to $5.64, compared with the average analyst forecast of $5.01.

The results represent "a decent beat and raise," with multiple products showing higher sales, Mizuho analyst Salim Syed said in a research note, while noting that some of the sales gains were attributed to accounting changes.

Shares of Amgen ( AMGN ), which closed a fraction higher, were up 1% in after-hours trading at $299.50.

Amgen ( AMGN ) said third-quarter sales of cholesterol-lowering drug Repatha rose 40% from a year earlier to $794 million on higher demand.

Sales of older arthritis drug Enbrel fell 30% to $580 million due to a 38% price drop driven by changes in the U.S. Medicare health plan for people age 65 and older and hospital purchases at favorable pricing.

The company said it expects to have data before year-end from two key mid-stage MariTide studies. One is testing the drug in obese or overweight adults with or without type 2 diabetes, and the second is looking at MariTide as a treatment for type 2 diabetes. Amgen ( AMGN ) also said it has completed enrollment in two Phase 3 studies for similar patient populations.

MariTide is an antibody linked to a pair of peptides that activate receptors for the appetite- and blood sugar-reducing hormone GLP-1 while simultaneously blocking a second gut hormone called GIP.

Adjusted third-quarter operating expenses rose 18% from a year earlier, while research and development costs jumped 31%. Amgen ( AMGN ) said its tax rate increased 4.8 percentage points due to a change in product mix.

For the full year, Amgen ( AMGN ) raised its outlook for adjusted earnings and now expects $20.60 to $21.40 per share on revenue of $35.8 billion to $36.6 billion. It had previously forecast earnings of $20.20 to $21.30 per share on revenue of $35 billion to $36 billion.

Analysts, on average, have estimated 2025 earnings of $21.04 per share on revenue of $35.67 billion.