By Tamara Mathias

(Reuters) – Viking Therapeutics Inc’s shares more than doubled in value on Tuesday after promising data from a mid-stage trial of its fatty liver drug were seen as topping that from larger rival Madrigal Pharmaceuticals .

Viking said it plans to develop its VK2809 drug as a treatment for non-alcoholic steatohepatitis (NASH), a type of fatty liver disease which is linked to rising levels of obesity and lacks any approved treatments.

In NASH patients, excess fat is stored in the liver, which becomes inflamed and poses the risk of scarring and cancer. Analysts have estimated the market in treating the disease could be worth as much as $30 billion.

Madrigal also saw its stock more than double in June after mid-stage trial data showing its drug reduced liver fat in NASH patients. Madrigal shares slumped nearly 12 percent to $201.43 on Tuesday morning while Viking’s rose as much as 142 percent.

“While we acknowledge all the caveats associated with cross-trial comparison … we believe VK2809 achieved numerically better results than Madrigal’s MGL-3196,” said Andy Hsieh at William Blair.

In Viking’s trial, patients given VK2809 saw a median reduction of between 57 percent and 60 percent in liver fat, while LDL-C or “bad cholesterol” levels dropped by a fifth or more.

The results appeared to exceed those from all other oral drugs currently in development for NASH, Viking said.

The positive data could potentially shorten the length and size of future trials, Viking Chief Executive Brian Lian said.

“We do have some flexibility, given the potency here. We wouldn’t have to do 5,000 patients or something,” Lian said on a conference call with analysts.

After hitting an all-time high of $24, Viking shares were last up 103 percent at $21.06.

(Reporting by Tamara Mathias in Bengaluru; Editing by Sai Sachin Ravikumar)