Viking Therapeutics is developing VK2735, a GLP-1/GIP drug that could compete with Eli Lilly's Zepbound. Its stock is soaring.

Viking Therapeutics is working on several weight-loss drugs, including VK2735, a GLP-1/GIP drug that's still in clinical trials.

An experimental drug developed by Viking Therapeutics helped people maintain their weight loss even after stretching the doses to once a month or every other week.

Viking's stock (VKTX) was up about 24% on Tuesday morning after the San Diego-based company revealed the new Phase 1 data for VK2735, a GLP-1/GIP drug that's still in clinical trials.

Viking is one of dozens of companies trying to develop better weight-loss drugs after the runaway success of Novo Nordisk's (NVO) (DK:NOVO.B) Wegovy and Eli Lilly's (LLY) Zepbound. That includes medications that use amylin rather than GLP-1 to trigger weight loss; drugs with fewer frustrating side effects, like gastrointestinal discomfort or the loss of muscle; or options to help people maintain their weight loss.

At the same time, there is ongoing debate about whether any of these new drugs can compete with Lilly's medications, which include the GIP/GLP-1 injection Zepbound, the GLP-1 pill Foundayo and retatrutide, a highly anticipated drug candidate that targets GLP-1, GIP,and glucagon.

"The fact that this trial delivered precisely as expected reinforces our prevailing thesis that this molecule is superior to [Zepbound] because basically all available data suggest it is," Cantor analyst Steve Seedhouse wrote in a note on Tuesday.

Other analysts agreed. Before the data was announced, Oppenheimer analyst Jay Olson told investors that weight loss won't be the main differentiator between Zepbound and Viking's drug. Instead, "VK2735 should compete effectively on long-term persistence, flexibility, convenience, and continuity of care," he said.

In the first part of Viking's study, which focused on weight loss, 180 adults with obesity received either the drug or the placebo once a week. Those who got the medication lost between 16.2% and 18.% of their body weight.

The second part of the study looked at whether longer dosing intervals could help people maintain their weight loss. In that part of the study, participants who received a dose of the experimental drug every other week maintained at least 90% mean weight loss, compared with 61% who received the placebo. Those who took the medication once a month maintained at least 80% mean weight loss.

The company is testing both oral and subcutaneous forms of the drug.

"Flexible dosing approaches will provide both patients and their providers with new options for improving long-term adherence to therapy and sustained weight management," Viking CEO Brian Lian said in a news release, "both of which are essential to realizing the most critical benefits of weight loss, such as improved cardiovascular health, enhanced physical function, and increased quality of life."

Viking's stock is up 43.7% so far this year.

-Jaimy Lee