Assembly Biosciences Announces $30.1 Million Investment & Accelerated Funding From Gilead

Assembly Biosciences, Inc. recently announced an equity investment of $20.1 million by Gilead Sciences, Inc.  to purchase additional Assembly Bio common stock and an amendment to their collaboration to advance the research and development of novel antiviral therapies with $10 million in accelerated funding. With the new equity investment, Gilead increases its equity ownership of Assembly Bio to 29.9%.

Funding received from Gilead will support the advancement of Assembly Bio’s clinical pipeline of antiviral therapeutic candidates for herpesviruses, hepatitis D virus (HDV) and hepatitis B virus (HBV). Assembly Bio expects to release data from multiple ongoing clinical studies in the coming year, including the interim Phase 1b proof-of-concept data readout for ABI-5366 projected for the first half of 2025.

The amendment to the collaboration agreement adjusts the option timepoints and option payment structure for ABI-6250, an orally bioavailable viral entry inhibitor for the treatment of HDV, to support updated clinical strategies to accelerate and optimize program development. As part of this amendment, $10 million of option-related payments for this program have been accelerated.

“Gilead’s further investment strengthens our balance sheet as we look ahead to multiple key clinical data readouts for our novel antiviral candidates in 2025,” said Jason Okazaki, chief executive officer and president of Assembly Bio. “In addition, we expect our updated clinical plan for ABI-6250 to significantly reduce the development timeline for the compound. Together, the amendment and additional investment will help advance our programs expeditiously and highlight the collective efforts of our organizations to change the treatment paradigm for people affected by serious viral diseases.”

Since the collaboration with Gilead was announced in October 2023, Assembly Bio has initiated clinical studies for four small molecule antiviral candidates. In mid-2024, a Phase 1a/b study for ABI-5366, a long-acting helicase-primase inhibitor for treatment of recurrent genital herpes and a Phase 1b study for ABI-4334, a next-generation capsid assembly modulator for treatment of chronic HBV infection, were initiated. In December 2024, Assembly Bio initiated dosing in the Phase 1a portion of a Phase 1a/b study for ABI-1179, a long-acting helicase-primase inhibitor for treatment of recurrent genital herpes contributed by Gilead under the collaboration, and has received regulatory clearance for a Phase 1a study for ABI-6250.

Assembly Bio will receive $10 million in accelerated funding under the collaboration agreement and a $20.1 million equity investment from Gilead. This equity investment at a premium will increase the percentage of the outstanding voting stock of Assembly Bio owned by Gilead from approximately 19.9% to 29.9% as of the date of closing.

The accelerated funding amount reflects a portion of option-related payments that Assembly Bio is eligible to receive for ABI-6250 and will be creditable against future payments under the collaboration agreement. In addition, Gilead and Assembly Bio have amended the option-related payments and option timepoints for this program to support potential accelerated development strategies. The scope of Gilead’s option and Assembly Bio’s right to opt-in to share profits and costs in the United States are unchanged.

With the accelerated $10 million payment resulting from the collaboration amendment and the $20.1 million additional equity investment, Assembly Bio expects its cash runway to extend to mid-2026.

ABI-5366, ABI-1179, ABI-4334 and ABI-6250 are investigational and not approved anywhere globally. Their efficacy and safety have not been established. More information about clinical trials with ABI-5366, ABI-1179, ABI-4334 and ABI-6250 is available at www.clinicaltrials.gov.

Assembly Biosciences is a biotechnology company dedicated to the development of innovative small-molecule therapeutics designed to change the path of serious viral diseases and improve the lives of patients worldwide. Led by an accomplished team of leaders in virologic drug development, Assembly Bio is committed to improving outcomes for patients struggling with the serious, chronic impacts of herpesvirus, hepatitis B virus (HBV) and hepatitis delta virus (HDV) infections. For more information, visit assemblybio.com.