(Bloomberg) -- Insatiable demand for weight-loss drugs has made the market so feverish that any positive mention of a potential obesity therapy can send a company’s stock surging — even if those treatments may still be years away. 

After Amgen Inc.’s chief executive officer, Robert Bradway, said he was “very encouraged” by early results of an experimental obesity shot, the stock on Friday leapt 16%, its biggest gain since 2009. That’s despite no new data being released on the drug — which is in mid-stage trials — and before the approval process has even begun. 

The CEO’s upbeat remarks not only lifted Amgen shares, but also sent Novo Nordisk A/S, the Danish maker of hit drugs Wegovy and Ozempic, tumbling by more than 5%. Eli Lilly & Co., which makes weight-loss shot Zepbound, fell almost 3% in early trading Friday.

The potential size of the obesity drug market helps explain the excitement: Analysts at Goldman Sachs forecast it could hit $100 billion by 2030. Optimism over soaring sales has driven Novo Nordisk’s market capitalization above $500 billion this year, reinforcing its position as Europe’s most valuable listed company. Lilly’s shares are up more than 75% in the past 12 months. 

Novo and Lilly are leading now with drugs that mimic the glucagon-like peptide-1, or GLP-1, hormone that the body naturally releases after a meal. But there are multiple drug candidates waiting in the wings that could disrupt that duopoly in the future. 

Here’s a look some of the most promising rival drugs: 

Amgen

Amgen’s two-part drug MariTide, which includes an antibody-drug conjugate, works differently than Wegovy or Zepbound and is taken monthly, rather than weekly. An early study showed patients lost as much as 14.5% of their body weight in 12 weeks. 

Boehringer Ingelheim/Zealand Pharma

Boehringer Ingelheim GmbH and Zealand Pharma A/S are collaborating on a weekly obesity shot which mimics the blood sugar-regulating hormone glucagon as well as GLP-1. Boehringer is testing the drug, known as survodutide, for liver disease, with promising mid-stage results this year, as well as in obesity.

Viking Therapeutics

La Jolla, California-based Viking Therapeutics Inc. is developing both a weight-loss pill and a shot. An early study of the pill showed that patients lost an average of 3.3% of their body weight in 28 days compared with a placebo; another study of the injection showed patients lost as much as 14.7% of their weight in 13 weeks. The shot just completed phase 2 studies, while the pill is being moved into mid-stage trials.

Altimmune

Altimmune Inc.’s drug pemvidutide combines GLP-1 with a hormone called glucagon and has shown it can help patients lose as much weight as Wegovy. It also minimized muscle decline, a side effect of weight-loss shots, in a mid-stage trial. The company is meeting with the US Food and Drug Administration in the second half of the year to chart a path forward.

Structure Therapeutics

Results from an early-stage trial of Structure Therapeutics Inc.’s oral weight-loss drug, known as GSBR-1290, showed patients with obesity lost about 4.9% of their weight and none of them had to discontinue taking the drug because of side effects. 

AstraZeneca/Eccogene 

AstraZeneca Plc is developing an experimental obesity pill with Chinese biotech Eccogene that it said could be potentially cheaper than current blockbuster shots. Known only as ECC5004, the oral pill is in early stage trials and is “many years from market,” according to Bloomberg Intelligence’s John Murphy and Sam Fazeli. 

Pfizer

Pfizer Inc. discontinued a twice-daily version of its weight-loss pill danuglipron last year, after studies showed high rates of side effects like nausea and vomiting. The drugmaker is now in the early stages of testing a once-daily version and expects to share data on it this year.

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