An HBV program built on ingenuity, vision and experience

Our goal is to discover and develop finite and curative therapies for those chronically infected with hepatitis B virus (HBV), and we believe we have unique capabilities that will enable us to bring the first therapeutic innovation in decades and improve cure rates for individuals with chronic HBV infection. Our strong scientific expertise in discovering small molecules targeting the HBV core protein has made us a leader in the field.

HBV—one of the world’s most prevalent diseases

Chronic hepatitis B virus (HBV) infection is a debilitating disease of the liver that afflicts approximately 296 million people worldwide, as estimated by the World Health Organization. HBV is a global epidemic that affects more than twice the number of people than hepatitis C virus (HCV) infection and human immunodeficiency virus (HIV) infection combined—with a higher morbidity and mortality rate. HBV is a leading cause of chronic liver disease and need for liver transplantation, and up to one million people worldwide die every year from HBV-related causes.

The current standard of care for patients with chronic HBV infection is life-long suppressive treatment with medications that reduce, but do not eliminate, the virus, resulting in very low cure rates and enormous unmet need.

Assembly’s unique approach

Our unique approach aims to maximize antiviral suppression by targeting multiple points in the HBV replication cycle while also engaging the arms of the immune system that have been shown to be able to affect a curative response. Assembly Bio is advancing next-generation core inhibitors (CIs), a novel class of oral antivirals, into clinical development. These novel next-generation CIs have been optimized to potently disrupt both viral replication and, importantly, prevent the establishment and replenishment of new covalently closed circular DNA (cccDNA). cccDNA is the viral reservoir that drives HBV’s life-long persistence in patients and first-generation core inhibitors have not demonstrated adequate potency to sufficiently block its formation in patients. Further, the current standard of care (nucleoside analogs) can only inhibit production of new virus – and does so incompletely.1

1Marcellin, et al, AASLD 2014, Poster 1861

A pipeline strategy designed to free HBV patients from lifelong therapy and target other serious viral diseases

In our relentless pursuit to discover novel antivirals to treat serious viral diseases and to bring finite and curative treatments to HBV patients, our pipeline is focused on the following areas:

  • Potent, next generation core inhibitors designed to maximally block the formation of new cccDNA
  • Novel , bioavailable small molecule inhibitors of HBV and HDV viral entry that potently block infection of hepatocytes for both viruses
  • Novel, bioavailable, liver-focused small molecule agonists of the interferon pathway that are able to activate antiviral cellular responses as well as engage the innate and adaptive immune systems
  • Additional antiviral discovery programs aimed at addressing unmet needs for viruses other than HBV

Potent next generation core inhibitors

We have two potent, next generation CI product candidates, ABI-H3733 (3733) and ABI-4334 (4334), both optimized for significantly increased potency against cccDNA formation and new virus production versus first-generation core inhibitors. A Phase 1 study of 3733 is ongoing and 4334, which has a potential best-in-class profile, is expected to initiate clinical studies in 2022.

Research programs advancing new small molecule compounds with novel targets and mechanisms

Our research team is focused on proprietary research that has the potential to accelerate progress toward HBV cures and to discover novel antivirals to treat other serious viral diseases. We are currently advancing an early-stage program evaluating a novel small molecule approach to inhibit viral entry for HBV and hepatitis delta virus (HDV), which is estimated to impact approximately 5 percent of those chronically infected with HBV – approximately 12 million people globally. We have also recently announced our early-stage novel orally-bioavailable interferon-α receptor (IFNAR) agonist program that is designed to selectively activate the interferon-α pathway in the liver, and are currently exploring initiatives targeting other viruses outside of HBV.

More information about our clinical trials can be found at