04:00 PM EST, 11/26/2024 (MT Newswires) -- Shares of Amgen ( AMGN ) fell on Tuesday after the biotech company reported results for a phase 2 study of its obesity injection, which fell short of efficacy expectations, Mizuho Securities said.

Amgen ( AMGN ) announced that its investigational drug, MariTide, demonstrated up to 20% average weight loss over a 52-week period for people living with obesity or overweight issues without type 2 diabetes.

For obese and overweight patients that have type 2 diabetes, who typically lose less weight on glucagon-like peptide-1 therapies, the efficacy rate was up to 17%, according to Amgen ( AMGN ).

The results provided the company confidence to move forward with a phase 3 study, Amgen ( AMGN ) Chief Scientific Officer Jay Bradner said in a statement. "We are very excited by MariTide's differentiated profile, with clinically meaningful attributes of substantial and progressive weight loss," he said.

However, Mizuho Securities Managing Director Salim Syed said the weight loss achieved was at the "low end of expectations" and "numerically below" Viking Therapeutics' ( VKTX ) weight loss drug candidate.

Shares of Amgen ( AMGN ) were down 5.9% just ahead of market close on Tuesday, while Viking's climbed 2.9%.

While management's tone remains positive, "we continue to have our reservations -- the market's general buy thesis might be over," Syed said.

Amgen ( AMGN ) said the most common adverse events in the phase 2 study were gastrointestinal related, including nausea, vomiting and constipation. The company reported an 11% discontinuation rate in the dose escalation arms due to adverse effects while the rate related to gastrointestinal side effects was less than 8%.

Price: 276.67, Change: -17.33, Percent Change: -5.89