Mark Murray
Analyst · Chardan
Thanks, Adam and thank you to everyone who is joining us on the call and the webcast today. We're very pleased with the HBV product pipeline progress that we're making at Arbutus. Our lead candidate, ARB-1467, is an RNA interference agent which targets all of the viral proteins and has generated very promising data in an ongoing Phase II clinical trial and will yield more efficacy data from so-called Cohort 4 in September. These data have set a high bar for our follow-on RNA interference agent, ARB-1740. And we're announcing today that we're no longer investing in ARB-1740 development because it does not provide a sufficient clinical potency advantage over ARB-1467 in HBV patients. Our lead capsid inhibitor, AB-423 is progressing through an ongoing Phase I study in healthy volunteers which will enable the start of multiple ascending dose study in HBV patients by the end of this year. We're also making significant progress in our preclinical pipeline. I'm very pleased to announce today, that we recently nominated 2 new development candidates, AB-506, from our second-generation capsid inhibitor program; and AB-452 from our HBV RNA destabilizer program. We have previously referred to this compound as a small molecule S-antigen inhibitor. You would hear more about these programs from Dr. Michael Sofia later in the call. As you know, we at Arbutus are committed to developing therapeutic solutions to chronic HBV, based on combinations of drugs with complementary mechanisms of action. We believe that the first step toward improved curates for patients could be the development of a proprietary product, such as an agent that reduces S-antigen to very low, possibly undetectable levels, thereby benefiting patients that can be approved for use in combination with the current standard of care. Beyond this, we will continue to advance our other development stage products in combination with approved and proprietary products to further improve curates. Our current development efforts focus on direct-acting antiviral mechanisms designed to improve curates for patients by durably eliminating HBV S-antigen in DNA. Now given the importance of HBV S-antigen in the chronic infection and the need for its elimination, on the path to a cure, we have made a commitment targeting S-antigen that is a represented by multiple assets in our pipeline. First and foremost is ARB-1467 which has already shown the ability to significantly reduce serum S-antigen levels in 3-month dosing studies. Now to ensure that we have ever choose to eliminate S-antigen, we have nominated and will take into the clinic AB-452, our orally active agent which reduces S-antigen levels. We expect that to enter the clinic next year. We will also bring forward a subcutaneously substantive delivered HBV GalNAc RNAi, an agent which we expect to nominate for developments early next year. All of these direct acting antiviral agents have multiple effects on several aspects of the HBV life cycle, including a significant reduction in S-antigen production. This profile offers the potential for each of these drugs to improve the current standard of care and potentially form the backbone of future combinations with other new agents. But before I provide an update on the clinical development of ARB-1467, I would like to address one of the most frequently asked questions posed to us by investors. And that is, what is a meaningful threshold of S-antigen reduction. I'm sure we would all agree with, the greater the reduction in S-antigen, the better. We're focused on an absolute level of reduction. We believe that reducing S-antigen to low levels close to the level of detection, rather than an arbitrary log drop will be the most important end point. And that is what we're trying to achieve with ARB-1467. At the EASL Conference in April, we presented results from Cohorts 1,2 and 3 of our Phase II study of ARB-1467 and showed significant S-antigen reduction with 3 monthly doses of ARB-1467 in combination with new treatment. These results showed an additive step-wise reduction in S-antigen, but suggested that we could see greater reductions in S-antigen if we dosed more frequently or longer. Cohort 4 is testing just that with 3 months of bi-weekly dosing. We will provide top line results from this cohort in September. These results will be factored into the line of a new ARB-1467 study to be initiated later this year which will include NUCs in the course of interferon treatment as an immune stimuli. Now I would like to briefly review our decision to discontinue development of our follow-on RNAi agent, ARB-1740. We dosed patients in 2 dose per host of ARB-1740. There were no safety concerns associated with ARB-1740, but the lack of a strong potency advantage relative to ARB-1467 has led us leverage to conclude that our investment should go to ARB-1467, a very promising product candidate which is further ahead in development. Now I'll turn over the call to Mike to discuss our recent pipeline. Mike?