Chasing Madrigal, Viking sails higher after NASH therapy slays midphase test

Viking Therapeutics’ nonalcoholic steatohepatitis (NASH) candidate has sailed past another clinical test. The phase 2b study linked VK2809 to mean relative changes in liver fat of up to 51.7% without causing widespread gastrointestinal side effects, keeping it tucked in behind Madrigal Pharmaceuticals’ near-approval asset.

The clinical trial compared four doses of the selective thyroid receptor-beta agonist VK2809 to placebo in more than 200 patients with NASH, as proven by a biopsy. After taking the oral candidate for 12 weeks, participants underwent imaging to assess changes in liver fat, the buildup of which is a defining characteristic of NASH.

Participants who took 10 mg of VK2809 every other day experienced a mean relative change in liver fat of 51.7%. Viking saw smaller reductions in liver fat at lower doses, but most patients in all the cohorts had a 30% or greater change in liver fat, a threshold that the biotech said is associated with greater likelihood of histologic response in NASH. In the high-dose arm, 84.9% of patients exceeded the 30% threshold.

The question of whether VK2809 causes a histologic response, which the 12-week data cannot answer, is critical to the prospects of the candidate because of its status as part of the FDA’s favored endpoints for late-phase trials. Viking is assessing the rate of resolution of steatohepatitis on overall histopathological reading and no worsening of liver fibrosis using a secondary, 52-week endpoint in the phase 2b trial.

Data on the secondary endpoint will provide a fuller picture of whether VK2809 is likely to clear the bar for regulatory success, but, for now, the signs are encouraging for Viking. VK2809 emerged from the phase 2b with a clean safety profile, with the rate of nausea coming in higher in the placebo group than most of the treatment arms, including the 10-mg dose, and little effect on the rates of diarrhea apparent.

The data on gastrointestinal adverse events point to one way Viking may be able to differentiate its candidate from Madrigal’s resmetirom. Madrigal linked the rival candidate to higher rates of nausea and diarrhea than placebo in a phase 3 trial, although, with a filing for approval imminent, the biotech looks set to enjoy first-mover advantage over Viking.

Shares in Viking climbed 11% to $24.50 in premarket trading. The stock has benefited from the success of Madrigal and Viking’s own data, which have helped drive the share price up by more than 800% over the past year.