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Antios Therapeutics Announces Agreement with IRBM, INGM and OSR to Acquire Fourth-Generation HBV Capsid Assembly Modulators (CAMs)

MENDHAM, N.J. and ROME, ITALY November 15, 2021 – Antios Therapeutics, Inc. (“Antios”), a clinical-stage biopharmaceutical company developing innovative therapies to treat and cure chronic hepatitis B virus (HBV), and IRBM, a drug discovery and early development research institute and global contract research organization, announced today they entered into an agreement for Antios to purchase the IP rights to a novel series of fourth-generation capsid assembly modulators (CAMs) being developed for the treatment of HBV. The CAMs were originated and developed at IRBM in conjunction with Promidis/CNCCS (a subsidiary of IRBM), Istituto Nazionale Genetica Molecolare (INGM) and San Raffaele Hospital (OSR). These CAMs enable the selection of a new pipeline candidate, which will be the second molecule in Antios’ HBV portfolio. The total potential value of the deal to the Italian sellers/parties is up to $50 million, in addition to royalties.


Derived from a novel chemical scaffold, the CAMs have shown a strong in vitro and in vivo activity in a transgenic mouse model of HBV infection. Early in vivo data point to a differentiated mechanism of action which prevents accumulation of empty capsids, unlike most CAMs, and potentially provides for a more targeted, productive clearance by the immune system. Pre-clinical candidate selection is anticipated in the first half of 2022 with clinical development beginning in mid-2023.


“Unlike traditional CAMs, which target capsid assembly and disassembly, we believe these molecules may have an additional mechanism of action. Their distinct potential in vivo, along with their pre-clinical activity profile to date, position our candidate selection with best-in-class potential among the field,” said Katherine Squires, PhD, Head of Research and Development at Antios. “These particular CAMs will expand the Antios portfolio of differentiated molecules and offer a unique addition to the development of a potentially curative regimen.”


“We hope that the development of these compounds can bring significant benefit to the 296 million people living with this devastating disease,” said Romano Di Fabio, PhD, Corporate Director of Small Molecule R&D at IRBM, whose team designed and then optimized this novel CAM series. Dr. Di Fabio holds more than 70 international patents.


"This agreement is a tribute to the potential of partnerships between Italian academia and industry experts to develop novel therapies to address unmet clinical need,” said Carlo Toniatti, Chief Scientific Officer of IRBM.


“We are pleased to find a home for this program with an experienced team that recognizes the unique potential of these compounds that, in pre-clinical research, showed differentiation from others in its class,” said Luca Guidotti, MD, PhD, a co-inventor and a pioneering HBV researcher who serves as Deputy Scientific Director at OSR.

“Antios, because of its focus on HBV, is the ideal company to guide this program through clinical trials and advance its journey toward potential commercialization,” said Raffaele De Francesco, PhD, Co-inventor of the novel CAM series and Head of the Virology Laboratory at INGM.

Antios’ lead Phase 2b clinical candidate, ATI-2173, is the only Active Site Polymerase Inhibitor Nucleotide (ASPIN) in clinical development, and has potential, if approved, to be the cornerstone of curative, once-daily HBV therapy. Pre-clinical data to date for ATI-2173, alone or combined with tenofovir disoproxil fumarate (TDF), indicate the potential for sustained HBV DNA suppression off treatment, unique among approved nucleosides and investigational anti-HBV therapies.


Destum Partners acted as business development advisor to Antios for this transaction. Closing of the transaction is subject to customary closing conditions, including clearance under the Italian Golden Power legislation.


About ATI-2173

ATI-2173, Antios Therapeutics' lead once-daily, oral drug candidate for treating HBV, is an investigational phosphoramidate prodrug of clevudine monophosphate. ATI-2173 has the potential, if approved, to become the cornerstone of a curative HBV regimen. It is the only Active Site Polymerase Inhibitor Nucleotide (ASPIN) in clinical development and its mechanism of action is complementary to other approaches that also seek to achieve a functional cure. ATI-2173 is currently in Phase 2b clinical development. The SAVE-1 (Sustained Anti-Viral Efficacy) trial is an ongoing, double-blind, randomized, placebo-controlled study of 30 patients designed to assess the safety and efficacy of 25 and 50 mg doses of ATI-2173 daily for 90 days in combination with tenofovir disoproxil fumarate (TDF) compared with TDF plus ATI-placebo (control) in chronic HBV-infected subjects.


About Antios Therapeutics, Inc.
Antios Therapeutics is a clinical-stage biopharmaceutical company focused on the development of innovative therapies to treat and cure viral diseases. Its lead drug candidate ATI-2173 – the only Active Site Polymerase Inhibitor Nucleotide (ASPIN) in clinical development – has the potential, if approved, to become the cornerstone of a curative therapeutic regimen for chronic HBV, a major unmet global health problem affecting up to 300 million people worldwide, more than hepatitis C and HIV combined. For more information, please visit




About IRBM

IRBM is a drug hunting company working primarily as an innovative contract research organization across all aspects of drug discovery and early development for different modalities – small molecule, peptides, and antibodies. IRBM fosters collaborations with organizations from the pharmaceutical, biotech and academic sectors to accelerate drug discovery from target validation and hit identification to candidate nomination. More than 200 scientists work at IRBM’s state-of-the-art R&D facility near Rome where projects are carried out “under one roof” enabling rapid cycle times and close integration of the scientific teams. IRBM’s scientists have discovered several drugs that are on the market, and more than 25 compounds have gone into clinical testing. The company was founded in 2010, as a spin-off from MSD. Now in its 11th year as an independent research organization, IRBM has laid the foundations to become a global Centre for Excellence in all aspects of drug discovery and early development. IRBM’s affiliate, Promidis, is based at the San Raffaele Hospital and conducts research with the objective to discover innovative drugs in areas of unmet need. IRBM is also part of The National Consortium and Collection of Chemical Compounds (CNCCS), a private-public consortium with a mission to identify compounds acting on innovative biological targets. It also acts as a center for translational research in rare, neglected and poverty-related diseases. Both Promidis and CNCCS together with IRBM were involved in the discovery and development of the fourth-generation CAM inhibitors. For more information visit  


About INGM

INGM is a biomedical research centre aimed at Preventive Precision Medicine with a special focus on genetics and epigenetics of immunological aspects of chronic diseases (autoimmune, infectious and tumoral). INGM develops translational research projects aimed at the identification of new biomarkers and novel therapeutic targets which could improve secondary and tertiary prevention of human chronic diseases. INGM projects exploit the most advance single cell omics technologies combined with the most advanced big data interrogation tools. For more information visit


About OSR

San Raffaele Hospital (OSR) is a large clinical-research-university hospital with more than 60 clinical specialties that provides advanced care for the most complex and difficult health conditions. OSR is part of Gruppo San Donato, the leading hospital group in Italy. Research at OSR involves more than 1,200 scientists and covers all fields of biomedicine. The overall biomedical innovation process is operative at OSR: from basic discoveries made in the labs to therapy design and test in pre-clinical models, up to first phase and pilot clinical trials in humans. The institute is recognized as a global authority in molecular medicine and gene therapy and is at the forefront of research in many other fields, including infectious diseases. OSR currently holds a portfolio of over 600 patents, most of which are licensed to industrial partners for further development. For more information, please visit:



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Last Updated: 16-Nov-2021