Arbutus' clinical challenges trigger stock slide
- Arbutus Biopharma disclosed Tuesday that it will delay the start of a Phase 1 trial for an experimental hepatitis B treatment, while initial results from Phase 2 results of another drug added to a stock slump this week that's erased more than half of the company's value.
- Amid the flurry of clinical updates, the company also announced a new chief development officer, Gaston Picchio.
- The Phase 2 results for Arbutus' lead drug, ARB-1467, were mixed. Of six patients enrolled, three did not reach the predetermined response criteria at week six to proceed to subsequent treatment.
Back in January 2015, when Arbutus was known as Tekmira, the stock was riding high at $25. In the first hours of trading Wednesday morning, the share price fell below $5.
The first bit of disappointing news announced Tuesday was the delay for a Phase 1 clinical trial of AB-452, Arbutus' oral hepatitis B virus RNA de-stabilizer. This was expected to move into the clinic in the fourth quarter of 2018, but the company said it would take additional time to "further characterize the compound following emerging nonclinical safety findings."
The company did not announce a target date for moving to the clinic.
ARB-1467, meanwhile, is at the head of Arbutus' pipeline. It uses an RNAi approach to target HBV replication and antigen production, and is in an ongoing 30-week study in HBV-infected patients.
While the results announced Tuesday were from only six patients, investors may have been spooked by the fact that three patients did not meet the prespecified response criteria at week 6 needed to move onto PEG-IFN treatment. Of the other three patients, two are not yet at six weeks, while the other is responding strongly, Arbutus said.
Elsewhere, AB-506, a second-generation small molecule capsid inhibitor, is moving into patients with HBV infection in a Phase 1a/1b trial that's expected to complete in the second quarter of 2019.
As its pipeline has advanced, Arbutus has also relied on licensing deals for its lipid nanoparticle (LNP) delivery technology, which can be used to deliver nucleic acids into the body.
The biotech has partnered with Roivant, Genevant Sciences and Gritstone Oncology. Most notably, Alnylam Therapeutics' RNAi therapeutic Onpattro (patisiran) uses Arbutus LNP technology.
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