Sorrento moves to buy delayed burst release naltrexone drug

signing contract
Long COVID is on Sorrento's list of target indications for its candidate. (Getty Images)

Sorrento Therapeutics has moved to buy a delayed burst release formulation of low-dose naltrexone from Aardvark Therapeutics. The formulation is set to move into a phase 2 fibromyalgia clinical trial this year.

Naltrexone is an opioid-receptor antagonist used in 25-mg to 50-mg daily doses in the management of alcohol and opioid dependence. Aardvark has identified an opportunity to modify the release of the molecule to unlock opportunities in indications including chronic pain, fibromyalgia and lasting effects of coronavirus infection, a condition known colloquially as long COVID.  

Interest in the indications is underpinned by evidence that low-dose naltrexone, typically 4.5 mg a day, has properties such as analgesia and anti-inflammatory effects that are not seen when it is given at higher doses. 

Sorrento, through its majority-owned subsidiary Scilex Holding Company, is now poised to help find out whether Aardvark’s delayed burst release formulation of low-dose naltrexone, ARD-301, can build on signs of efficacy seen in other studies. Sorrento and Scilex have entered into an exclusive licensing term sheet with Aardvark to acquire ARD-301.

Once the definitive agreement is executed, Scilex and Aardvark plan to collaborate on a phase 2 trial in fibromyalgia, an indication in which there remains unmet needs despite the availability of several treatment options. Some fibromyalgia patients take opioids to manage the pain. ARD-301 may offer an alternative to opioids. 

Sorrento and Scilex see multiple other therapeutic opportunities for ARD-301 and are planning to run phase 2 clinical trials this year. Long COVID is on the list of target indications. Understanding of long COVID, which is characterized by the persistence of a range of symptoms long after the infection has cleared, remains limited, but there is a potentially significant market given how many people have contracted the coronavirus.