Amgen is taking a new approach as it tries to stand out in a crowded field of drugmakers racing to develop the next blockbuster weight loss drug.

The biotech company is testing an injectable treatment that helps people lose weight differently from the existing injections from Novo Nordisk and Eli Lilly, and other obesity medicines in development. Amgen’s treatment, called MariTide, also appears to help patients keep weight off after they stop taking it.  

The drugmaker is also testing its drug to be taken once a month or even less frequently, which could offer more convenience than the weekly medicines on the market. 

It’s too early to say how competitive Amgen will be in the budding weight loss drug space, which Novo Nordisk and Eli Lilly have so far dominated.

Some analysts expect the market could be worth $100 billion by the end of the decade, potentially leaving room for new competitors to enter. Goldman Sachs also projects that between 10 million and 70 million Americans will be taking weight loss drugs by 2028.

The available data on Amgen’s injectable drug is promising, but it’s from a small, early-stage clinical trial. The Thousand Oaks, California-based company also is developing an oral medicine and other treatments for obesity, but has disclosed few details about them. 

Investors and health experts will likely get a better idea of Amgen’s prospects later this year: The drugmaker expects to release initial data from an ongoing mid-stage trial on MariTide, along with phase one data on its obesity pill. 

It’s also unclear whether Amgen’s treatments will be cheaper than the existing weight loss drugs, which cost around $1,000 per month.

Wegovy from Novo Nordisk and Zepbound from Eli Lilly lead a new class of obesity treatments that has drawn unrelenting patient demand — and investor interest — despite their hefty price tags and limited insurance coverage. 

Eli Lilly and Novo Nordisk have also struggled to offer enough supply of their treatments, which could give other companies a chance to win market share.  

Amgen’s drug offers a new twist on weight loss. 

Much like Wegovy and Zepbound, one part of Amgen’s treatment activates a gut hormone receptor called GLP-1 to help regulate a person’s appetite. 

But while Zepbound activates a second hormone receptor called GIP, Amgen’s drug blocks it. Wegovy does not target GIP, which suppresses appetite like GLP-1 but may also improve how the body breaks down sugar and fat.

Amgen’s decision to tamp down rather than boost GIP activity is based on genetics research suggesting that blocking the receptor is linked to lower fat mass and body weight, company executives have said. 

That appears to contradict how Zepbound works. Eli Lilly’s approach has proven successful: The treatment helped patients with obesity lose up to 22.5% of their weight after 72 weeks in a late-stage trial.

But Amgen’s MartiTide also was effective in a small, early-stage study. 

Patients given the highest dose of Amgen’s drug — 420 milligrams — every month lost 14.5% of their body weight on average in just 12 weeks, according to data from the phase one trial published last month in the journal Nature Metabolism. 

There’s a broader debate among researchers about why both approaches – blocking and activating GIP – are effective at promoting weight loss. 

One theory is that repeatedly activating the GIP receptor, as Zepbound does, ultimately causes the body to “self-regulate” itself and make sure there isn’t too much GIP activity, said Dr. Caroline Apovian, a director of the Center for Weight Management and Wellness at Brigham and Women’s Hospital.

That decreases GIP activity overall, which is thought to essentially mimic what Amgen’s drug achieves when it blocks the GIP receptor. But Apovian cautioned that “none of this is proven” and more data is needed.

“We think meaningful weight loss is already 5%. If you take Amgen’s drug, lose 14.5%, stop the drug and still have 11.2% weight loss after a few months, that’s significant,” said Dr. Holly Lofton, director of the Weight Management Program at NYU Langone Health and an obesity medicine physician. But she pointed out the need to study the treatment in a larger group of people. 

The sustained weight loss in Amgen’s study appears to contrast with results seen in clinical trials on Zepbound and Wegovy. Patients in those studies saw their weight rebound sooner after stopping the injections. 

Amgen’s MariTide “has that advantage where it’s just going to last a lot longer. Even if you give a high dose, you’re still going to have drug exposure in the body for a month or two months, so that clearly shows you don’t need to take it every week,” William Blair & Company analyst Matt Phipps told CNBC.

Phipps said people typically don’t want to get injections often, so some patients could prefer a monthly shot like Amgen’s MariTide for a disease that will likely require chronic treatment. 

But he noted that a patient’s choice may also depend on whether the level of weight loss and side effects of Amgen’s drug end up being on par with those of the existing weekly injections. 

Amgen’s ongoing phase two trial is exploring whether patients can take its drug even less frequently than once a month. 

Four out of eight patients in a group receiving the highest dose of the treatment withdrew before getting a second shot after reporting mild gastrointestinal issues, according to the study. But no other patients stopped taking the drug due to adverse events across any of the different dosing groups, Amgen Chief Medical Officer Paul Burton said during a conference earlier this month. 

“It’s a little early to jump to the conclusion that the drug won’t be tolerated by patients based on this phase one data,” William Blair & Company’s Phipps said.

Another part of Amgen’s phase two trial will also examine weight loss beyond 52 weeks, which will provide a clearer picture of how long the drug is effective.