Viking's oral pill reduces up to 12.2% weight but shares slump on higher patient exits

Aug 19 (Reuters) - Viking Therapeutics VKTX.O said on Tuesday its experimental weight-loss pill helped people with obesity lose up to 12.2% of their body weight over 13 weeks in a keenly watched study.

Yet, shares of the company slumped nearly 35% in premarket trading after data showed that more patients who received Viking's drug stopped taking the treatment, compared to those who received placebo in the mid-stage study.

Oral drugs are expected to take a significant share of the projected $150 billion weight-loss market, driven by their ease of use compared with injections such as Novo Nordisk's NOVOb.CO Wegovy and Eli Lilly's LLY.N Zepbound.

Viking's experimental oral pill is in a tight race with rival treatments being developed by the deeper-pocketed Novo and Lilly.

Earlier this month, Eli Lilly said its experimental daily pill, orforglipron, showed a 12.4% weight loss in patients in a late-stage study over 72 weeks. In a separate trial, Novo's oral semaglutide has shown a weight loss of 15% over 68 weeks. Both the oral drugs are expected to be launched next year.

Ahead of Viking's data, analysts expected weight loss in the range of 10% to 15% on average for the pill, known as VK2735. It had shown an 8.2% average weight-loss in a small early-stage trial.

About 20% of those who received the drug discontinued due to an adverse effect, compared to 13% on placebo in the 280-patient study. The most common reasons for treatment discontinuation were gastrointestinal side effects, the company said.

Like Lilly's Zepbound, Viking's drug also targets hormones known as GLP-1 and GIP that play a critical role in regulating the body's metabolism.

Viking is testing both the oral and under-the-skin injection forms of the drug in overweight patients who have who at least one weight-related comorbidity.