AllisonJeynes

BOARD CHAIR
  • Allison brings three decades of drug development, board and executive leadership experience to Mosaic
  • Most recently CEO of Avillion, a clinical development company, which she founded and led for 13 years, achieving a 100% success rate from Phase 3 development to FDA approval across multiple programs
  • Across her career she has contributed to 20 drug approvals, engaging with the FDA, MHRA and EMA, and has previously held senior positions at Wyeth, Bristol Myers Squibb and Novartis
  • A UK-trained oncologist, Allison obtained an MB ChB from the University of Sheffield and began her clinical career at the Royal Marsden Hospital, UK
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ThomasFuchs

CEO
  • Thomas brings 25+ years’ experience in leadership positions across early drug development, commercialisation and life cycle management.
  • Previously CEO at Cimeio Therapeutics and former Global Haematology Franchise Head at Roche-Genentech.
  • He holds an MBA from the Kellogg School of Management at Northwestern University and a Bachelor of Science in Business Administration from the University of Wisconsin-Stout.
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VinceO'Neill

Head of R&D
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EdHodgkin

NON-EXECUTIVE DIRECTOR
  • Ed was previously the first CEO and a board member of Autolus Therapeutics (NASDAQ:AUTL), and the former CEO of Resolution Therapeutics.
  • Within the Syncona life science team, Ed is involved in creation of new businesses and then fills executive roles within those companies to make them operational.
  • Ed was previously CEO of Biotica Ltd (Cambridge, UK), President & Chief Business Officer of BrainCells Inc (San Diego, CA), and VP, Business Development & Marketing at Tripos Inc (St Louis, MO).
  • Ed holds a degree and DPhil in Chemistry from the University of Oxford, and is a former Chairman of the BIA, the UK’s trade association for innovative life science companies.
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LaurenceReid

Non-Executive Director
  • Laurence is a highly experienced biotech entrepreneur and leader, currently serving as advisor and board member to companies moving through growth phases, strategic inflections, and other formative stages
  • Laurence was previously CEO, President and a Board member at Decibel Therapeutics, leading the company through IPO in 2021 and a 2023 acquisition by Regeneron
  • Other roles have included: CEO of Warp Drive Bio (2018 merger with Revolution Medicines), former entrepreneur in residence at Third Rock Ventures (including CEO roles in portfolio companies), and CBO at Alnylam Pharmaceuticals
  • Laurence holds a PhD in Biochemistry from the University of London, and BA in Natural Sciences from Cambridge University

RichardWooster

NON-EXECUTIVE DIRECTOR
  • Richard is currently Executive Partner at Syncona, and has over 30 years’ leadership experience across cancer genomics, drug discovery and development in both academia and industry
  • Previously CSO at several oncology biotech companies including Slingshot Therapeutics, Translate Bio, and Tarveda Therapeutics, and former Vice President and Discovery Performance Unit Head in Oncology at GlaxoSmithKline.
  • Richard began his career at the Institute of Cancer Research where he discovered the BRCA2 gene, and as a founder of the Cancer Genome Project at the Wellcome Trust Sanger Institute where mutations in BRAF were first discovered
  • Richard holds a PhD from the University of Dundee and has co-authored over 100 publications, book chapters, and patents
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MathewGarnett

CO-FOUNDER
  • Mathew is a Senior Group Leader at the Wellcome Sanger Institute, and has over 20 years’ experience in genomics and cancer therapeutics.
  • Mathew is the Sanger Scientific Lead for Open Targets, which aims to use genome-scale experiments and analysis to evaluate new therapeutic targets.
  • Mathew performs CRISPR-Cas9 genetic screens in cancer cells to identify new drug targets, which led to the discovery of Werner Syndrome helicase as a synthetic-lethal target in microsatellite unstable cancers.  He is also the developer of leading, widely-used cancer therapeutics resources including DepMap and GDSC.
  • Mathew completed his PhD in 2005 in the laboratory of Richard Marais at The Institute of Cancer Research (London, UK), where he was involved in the discovery and characterisation of BRAF as a human cancer gene.
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EmileVoest

Co-Founder
  • Emile is a professor of medical oncology and Senior Group Leader at the Netherlands Cancer Institute and Oncode Institute.
  • Emile is a former Chairman of the board of Cancer Core Europe, a collaboration of 7 excellent comprehensive cancer centres.
  • Emile is the founder of multiple precision medicine programs, and is a global leader in translational research with an emphasis on genetics, tumour organoids and immunology.
  • Until 2021, Emile served as executive medical director of the Netherlands Cancer Institute. He is also an independent, non-executive board member of Sanofi, is co-founder and serves on the non-executive board of the Hartwig Medical Foundation.
     
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The Combination Oncology People™

Targeting the ‘Holy Grail’ of Cancer Therapy

TP53 is the master tumour suppressor gene, dysregulated in around half of all cancers, and once considered an ‘undruggable’ protein target. Inhibition of p53’s key negative regulator, MDM2, has unlocked the therapeutic potential of p53 re-activation and is a clinically-validated mechanism.

Mosaic is developing ASTX295, a highly potent, next-generation, MDM2 antagonist that is designed to be best-in-class, for use in combination across a range of haematological and solid cancers.

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ASTX295, A Highly Differentiated MDM2 Antagonist

AST295 exhibits a short human half-life of approximately 4 hours, overcoming the limitations of earlier-generation MDM2 inhibitors due to its unique bone marrow-sparing safety profile. The short half-life enables pulsatile p53 pathway modulation, preventing sustained myelosuppression whilst maintaining efficacy against tumours.

Re-activating the ‘guardian of the genome’

The p53 protein is a cell’s primary tumour suppressor and a critical regulator of cell cycle arrest and apoptosis. Cancer cells frequently suppress p53 through a variety of mechanisms, making the p53 pathway one of the most commonly disrupted pathways in cancer. Restoring p53 function has emerged as a compelling therapeutic strategy across haematology and oncology.

MDM2 is the primary negative regulator of p53, suppressing its activity by targeting it for degradation. As a result, MDM2 has emerged as a high-potential therapeutic target. By blocking the p53–MDM2 interaction, an MDM2 inhibitor is intended to release this brake on p53 and restore its tumour suppressor function.

This therapeutic strategy is applicable to all tumours that retain functional (wild-type) TP53. Wild-type TP53 is retained in approximately 90% of haematological malignancies and about half of solid tumours, representing a substantial addressable patient population for MDM2-targeted therapies.

Mosaic Therapeutics is a unique combination of...

PEOPLE

PIPELINE

PARTNERSHIP

OUR PEOPLE 

A world-class team of 
leading scientists, clinicians, and commercial entrepreneurs – across discovery, development, and delivery.

  • ThomasFuchs

    CEO

  • VinceO'Neill

    Head of R&D

  • MathewGarnett

    CO-FOUNDER

  • EmileVoest

    Co-Founder

  • AllisonJeynes

    BOARD CHAIR

  • EdHodgkin

    NON-EXECUTIVE DIRECTOR

  • LaurenceReid

    Non-Executive Director

  • RichardWooster

    NON-EXECUTIVE DIRECTOR

  • MathewGarnett

    CO-FOUNDER

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ASTX295: Prospectively Designed to Enable Combination Use

Despite the compelling therapeutic rationale, first-generation MDM2 inhibitors have been constrained by dose-limiting, on-target haematologic toxicities, particularly thrombocytopenia and neutropenia, resulting in a narrow therapeutic window and limiting their potential for combination therapy.

ASTX295 was intentionally designed with high potency and a short 4-6 hour half-life to produce transient, pulsatile activation of the p53 pathway while minimizing sustained p53 activation in normal bone marrow. This differentiated pharmacokinetic profile is intended to enhance the therapeutic index by maintaining antitumour activity while reducing haematologic toxicity.

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Scientific and Clinical Rationale

PRECLINICAL DATA

In human tumor xenograft mouse models, ASTX295 produced transient induction of p21, a downstream target of p53, peaking approximately 6 hours after dosing and returning to baseline by 24 hours, demonstrating the intended pulsatile activation of the p53 pathway. Once-daily dosing achieved significant tumour growth inhibition, while equivalent drug exposures in non-tumor-bearing mice did not induce thrombocytopenia or neutropenia, demonstrating that robust antitumor activity can be achieved while minimizing haematologic toxicity.

CLINICAL EXPERIENCE

Consistent with the preclinical findings, the completed first-in-human study demonstrated that ASTX295 achieved the anticipated 4-6 hour pharmacokinetic half-life in humans whilst maintaining a favourable haematologic safety profile. At the recommended Phase 2 dose (RP2D), no Grade 3 or higher haematologic toxicities were observed as a single agent, supporting translation of the differentiated preclinical profile into the clinic. This uniquely enables combination use and has potential to enhance impact of DNA damaging agents.

OUR PIPELINE 

ASTX295 Development Plan

OUR PARTNERSHIPS 

An industry leading alliance of investors and partners that are working with us on our goal of developing novel combination therapies.

The Wellcome Sanger Institute

Mosaic is founded upon 15 years of world-leading research at the pioneering Wellcome Sanger Institute, the single largest contributor to the mapping of the human genome, with whom we retain a unique, bespoke relationship. This partnership empowers us to combine our expertise with their unrivalled knowledge, materials, and data.

“

The Sanger Institute is proud to have nurtured and spun out Mosaic Therapeutics from our world leading translational cancer genomics research. We have every expectation that 
Mosaic will successfully leverage their exceptional capabilities to improve outcomes for cancer patients worldwide.”

Matthew Hurles

DIRECTOR
THE WELLCOME
SANGER INSTITUTE

Our Investors

Working with Syncona supercharges everything we do through their investment, commercial expertise, and industry connections.

VISIT

Mosaic at Work

We are continually searching for talented individuals. If you are passionate about having an impact on patients’ lives and are driven to continuously learn and challenge the status quo, then please submit your CV.

JOIN THE TEAM

Our Values

COLLABORATION

Together, we deliver better outcomes. We respect and value each others’ contributions.

RESILIENCE

We are resolute in our endeavours. We believe we can overcome any challenge or obstacle.

AMBITION

We strive to find breakthrough solutions. We act with a sense of urgency and pace.

EXCELLENCE

We pride ourselves at being at the forefront of scientific discovery. We embody a spirit of continuous improvement.

Latest News & Events

Mosaic Therapeutics appoints Dr Allison Jeynes as Chair of the Board

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Mosaic Therapeutics appoints Dr Vince O'Neill, MD, as Head of R&D

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Mosaic Therapeutics to Present Poster for Lead Program MOS101 at the AACR Annual Meeting 2026

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Mosaic Therapeutics appoints Thomas Fuchs as CEO

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Mosaic Therapeutics in-licenses two clinical-stage oncology programs from Astex Pharmaceuticals for development as proprietary combination therapies

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Mosaic Therapeutics appoints Dr Barry Davies as CSO

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Note on the In-licensing of ASTX029 and ASTX295 oncology programs

Mosaic Therapeutics will continue treatment for all patients who were actively participating in the Taiho EAP programmes at the time of the IND transfer.

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