Amgen stock tumbled Tuesday after its highly anticipated weight-loss drug met Wall Street's expectations, but didn't beat out Eli Lilly's blockbuster, Zepbound.
Over the course of a year, nondiabetic patients who received a "monthly or less frequent dose" of Amgen's MariTide lost up to 20% of their body weight. That lines up with the highest dose of Lilly's Zepbound, analysts said. Zepbound and Novo Nordisk's Wegovy are weekly shots.
That was on the low end of expectations, Mizuho Securities analyst Salim Syed said in a report. The results were also numerically lower than Viking Therapeutics' shot, he said. In early-stage testing, Viking's weekly shot led patients to lose 14.7% of their body weight over 13 weeks. The company is also considering a monthly dose of the same drug.
Further, MariTide was also tied to a higher level of side effects than Zepbound. About 11% of patients dropped out of the MariTide study, compared to roughly 7% in a Phase 3 study of Zepbound. The side effects were mostly gastrointestinal in nature, lining up with expectations for the drug class.
Amgen remained upbeat on its weight-loss drug.
"I'm really excited about MariTide," Susan Sweeney said on a call Tuesday with reporters. Sweeney is the company's executive vice president of obesity and related conditions. "It is unique and differentiated, and we believe it has a competitive profile. And it's coming into a market that has high unmet medical need and is not being satisfied today."
Amgen Stock Takes A Hit
But Amgen stock dropped 4.8%, closing at 280.01. Shares of Eli Lilly and Novo Nordisk rose a respective 4.6% and 1.5%. Their advance was likely partly due to a proposal from President Joe Biden that Medicare and Medicaid cover the cost for weight-loss drugs. Viking shares popped 2.8% to 53.42.
Amgen's MariTide uses a different mechanism from Lilly's Zepbound. Zepbound mimics two hormones, GLP-1 and GIPR, to improve feelings of satiety and lower blood sugar markers. MariTide, on the other hand, mimics GLP-1 and puts the brakes on GIPR.
Importantly, there was no plateau in the weight loss among MariTide recipients.
"This could suggest potential for a more durable effect with long-term weight maintenance driven by increased dosing convenience attributable to the combined GLP-1 agonism and GIPR antagonism mechanism — which is a significant differentiator for MariTide compared to other GLP-1 agents," RBC Capital Markets analyst Gregory Renza said in a report.
Amgen's Jay Brander, chief scientific officer, declined to spell out which dosage and regimen the company is planning to move into Phase 3 testing. Amgen is planning a yearlong second part to its Phase 2 study, which will explore quarterly dosing and determine whether the weight loss continues. It also announced its Phase 3 test, dubbed Maritime.
"A number of questions remain but we see a drug that provides equivalent weight loss to tirzepatide much faster (52 weeks versus 72 weeks) with monthly dosing (vs. weekly dosing), albeit with a safety trade-off (higher rates and lengthy window of nausea and vomiting, albeit predominantly focused on the first dose)," Piper Sandler analyst Christopher Raymond said in a note.
Tirzepatide is the chemical name for Lilly's weight-loss drug Zepbound.
He kept his overweight rating on Amgen stock.
Nausea, Vomiting Rates
Nausea and vomiting were generally mild, transient and associated with the first dose, Amgen said in its news release. The company managed the side effects with a slower dosing schedule. Ultimately, 8% of participants dropped out of the study due to gastrointestinal side effects. Bradner noted 90% of patients are sticking around for the second part of the Phase 2 study.
RBC's Renza says the discontinuation rates were "on the higher end of our range but acceptable."
Notably, Amgen said there was no evidence on bone mineral loss among MariTide recipients. Amgen stock took a header on Nov. 12 after a report suggested MariTide was linked to bone mineral loss in early testing.
William Blair analyst Matt Phipps noted that a lower initial dose of MariTide led about 50% of patients to have nausea and resulted in vomiting for 20% of patients. That appears higher than the levels seen for Lilly's Zepbound and Novo's Wegovy.
Further, "the decision not to disclose individual 420-milligram efficacy arm leads investors to assume reduced efficacy when adding escalation or moving to every other month, despite management commentary that the efficacy was comparable across 420-milligram arms," he said in a report.
He rates Amgen stock an outperform. He sees MariTide as differentiated from approved GLP-1 drugs and those in development, largely due to its less frequent administration.
"We believe this will be appealing in which is largely becoming a consumer-driven market and, combined with manufacturing advantages, will result in meaningful market share despite being several years behind in development," he said.
'Truly Remarkable' Results
Amgen also said patients with type 2 diabetes lost up to 17% of their body weight with no plateau, and saw an up to 2.2% reduction in their HbA1c, a measure of blood sugar levels over time.
Amgen's Sweeney called the results "truly remarkable."
"Folks have been looking at monthly treatments, or trying to develop monthly treatments for diabetes for quite some time," she said. "This is the first and only monthly treatment that we've seen a 2.2 percentage drop in HbA1c."
Patients showed improvements across cardiometabolic measures, including blood pressure, triglycerides and high-sensitivity C-reactive protein. The latter increases when there is inflammation.
Amgen also noted that there were no significant increases in free fatty acids. In comparison, Leerink Partners analyst David Risinger noted, Lilly's Zepbound led to a roughly 7.5% decrease in free fatty acids in a pooled analysis of two studies. Free fatty acids are released from fat tissue called adipose. They are implicated in insulin resistance and heart disease.
Follow Allison Gatlin on X, the platform formerly known as Twitter, at @IBD_AGatlin.
