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Arrowhead Collaborator Presents Phase 2b Clinical Data from REEF-1 Study in Patients with Chronic Hepatitis B Infection

November 15, 2021 GMT

PASADENA, Calif.--(BUSINESS WIRE)--Nov 15, 2021--

Arrowhead Pharmaceuticals Inc. (NASDAQ: ARWR) collaborator Janssen Pharmaceuticals, Inc., one of the Janssen Pharmaceutical Companies of Johnson & Johnson, presented clinical data from REEF-1, a Phase 2b study of different combination regimens, including JNJ-73763989 (JNJ-3989), formerly called ARO-HBV, and/or JNJ-56136379 (JNJ-6379), and a nucleos(t)ide analog (NA) for the treatment of chronic hepatitis B virus infection (CHB). The data were presented in a late breaking oral presentation at The Liver Meeting, the Annual Meeting of the American Association for the Study of Liver Disease (AASLD).

JNJ-3989 is an investigational small interfering RNA (siRNA) that targets all hepatitis B virus (HBV) RNAs, thereby reducing levels of all viral proteins. JNJ-6379 is an investigational capsid assembly modulator (CAM-N) that inhibits viral replication by inducing the formation of non-infectious viral particles that are devoid of HBV DNA and RNA. Arrowhead entered into a license and collaboration agreement with Janssen in October 2018 to develop and commercialize JNJ-3989.


REEF-1 ( NCT03982186 ) is a Phase 2b, multicenter, double-blind, active-controlled, randomized study to assess the efficacy and safety over 48 weeks of monthly subcutaneous injections of JNJ-3989 (3 dose levels of 40, 100, and 200mg) and/or 250mg daily oral JNJ-6379 in combination with daily oral NA in currently not treated or virally suppressed patients with HBeAg positive or negative CHB. Patients were required to have HBsAg levels greater than 100 IU/mL to enter the study. The mean baseline HBsAg level was approximately 3.7 log 10 IU/mL across all study arms. The primary endpoint of the study is the proportion of patients meeting NA stopping criteria (ALT less than 3 times upper limit of normal, HBV DNA less than the lower limit of quantitation, HBeAg negative, and HBsAg less than 10 IU/mL) at the end of treatment (week 48).

Presentation Details:

Title: Efficacy and Safety of the siRNA JNJ-3989 and/or the Capsid Assembly Modulator (CAM) JNJ-6379 for the Treatment of Chronic Hepatitis B Virus Infection (CHB): Results from the Phase 2B REEF-1 Study
Authors: Man Fung Yuen, et al.
Publication Number: LO10
Session: Late Breaking Session 2

Select data presented include the following:

Pharmacodynamic Response in JNJ-3989 200 mg with NA cohort (n=94)


  • The greatest reduction in HBsAg was observed in the JNJ-3989 200 mg with NA cohort
    • A dose dependent response was observed in other cohorts
  • At week 48, 19.1% of patients met NA stopping criteria
  • Up to week 72, an additional 10.6% of patients met NA stopping criteria for a total of 29.7%
  • At week 48, the mean reduction in HBsAg from baseline was 2.6 log10
  • At week 72, the mean reduction in HBsAg from baseline was 1.9 log10
  • At week 48, 74.7% of patients achieved HBsAg less than 100 IU/mL


  • A dose dependent response was observed
  • JNJ-3989 200 mg (highest dose) arm at Week 48:
    • 19.1% of patients met the primary endpoint (NA stopping criteria) The greatest reduction of HBsAg levels from baseline (2.6 log 10 IU/mL)
    • 74.7% of patients achieving HBsAg <100 IU/mL
  • All regimens within this long-term study were generally well tolerated and have a favorable safety profile
  • Combination studies involving different mechanisms of action are ongoing

A copy of the presentation materials with full data may be accessed on the Events and Presentations page under the Investors section of the Arrowhead website.

About Arrowhead Pharmaceuticals

Arrowhead Pharmaceuticals develops medicines that treat intractable diseases by silencing the genes that cause them. Using a broad portfolio of RNA chemistries and efficient modes of delivery, Arrowhead therapies trigger the RNA interference mechanism to induce rapid, deep, and durable knockdown of target genes. RNA interference, or RNAi, is a mechanism present in living cells that inhibits the expression of a specific gene, thereby affecting the production of a specific protein. Arrowhead’s RNAi-based therapeutics leverage this natural pathway of gene silencing.

For more information, please visit, or follow us on Twitter @ArrowheadPharma. To be added to the Company’s email list and receive news directly, please visit

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Source: Arrowhead Pharmaceuticals, Inc.

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CONTACT: Arrowhead Pharmaceuticals, Inc.

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SOURCE: Arrowhead Pharmaceuticals, Inc.

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PUB: 11/15/2021 01:00 PM/DISC: 11/15/2021 01:01 PM