Replay launches its first HSV gene therapy company, Eudora, focused on retinal eye disease

  • First product company using Replay’s high payload capacity HSV vector
  • Utilizes a next-generation HSV delivery vector developed at the University of Pittsburgh by leading HSV scientist and entrepreneur Professor Joe Glorioso
  • Eudora founded by Joe Glorioso and distinguished entrepreneurs and retinal gene therapy experts Mark Blumenkranz, David Schaffer, and Vinit Mahajan

San Diego, California and London, UK, October 31, 2022 – Replay, a genome writing company reprogramming biology by writing and delivering big DNA, today announced the launch of Eudora, an HSV gene therapy company targeting genetic retinal diseases. It is the first of Replay’s product companies to leverage its high payload capacity herpes simplex virus (HSV) delivery vector, synHSV™. Eudora’s co-founders, Professors Joe Glorioso, Mark Blumenkranz, David Schaffer, and Vinit Mahajan, are seasoned entrepreneurs, and global leaders in the fields of HSV and retinal disease gene therapy.

Replay’s distinctive corporate structure separates technology development from therapeutic product development within disease area-specific product companies. Eudora is the first of Replay’s four synHSV™ gene therapy product companies, with the other three applying big DNA gene therapy to monogenic diseases of the brain, skin, and muscle.

Eudora’s pipeline includes retinitis pigmentosa, Stargardt disease, and Usher syndrome type 1B. Replay’s synHSV™ technology is a high payload capacity gene-deleted HSV-1 vector capable of delivering up to eight times the payload of adeno-associated virus (AAV) vectors. This facilitates the delivery of genes that are too big to fit into AAV and enables polygenic gene therapy. Replay is, additionally, developing an HSV vector that can deliver up to 30 times the AAV payload.

Adrian Woolfson, Executive Chairman, President and Co-Founder of Replay, commented: “Replay’s differentiated corporate structure allows its platform technologies to be applied to indications in areas of high unmet medical need across a portfolio of focused product companies. Eudora, the first of these, is led by some of the world’s most authoritative experts in HSV and retinal gene therapy who are also seasoned entrepreneurs, and three of which have co-founded publicly listed companies. Eudora provides Replay with the first opportunity to showcase the differentiated payload capacity of its synHSV™ technology, which we believe has transformative potential within the field of eye gene therapy and beyond.”

Lachlan MacKinnon, CEO and Co-Founder of Replay, said: “We are thrilled to be working with such a distinguished group of scientists, entrepreneurs, and physicians. Eudora is the first of a series of Replay product companies, each of which showcases unique aspects of our suite of proprietary genomic medicine platform technologies. We believe that our distinctive paradigm of separating platform development from product development represents the most optimal structure for efficiently leveraging the potential of our genomic medicine technology platforms and for bringing forward a new generation of genomic medicines to patients with high unmet medical needs.”

Professor Joe Glorioso, PhD, Co-Founder of Eudora, commented: “The incorporation of Eudora presents a unique opportunity to leverage Replay’s next-generation HSV-1 delivery platform, developed by my team at the University of Pittsburgh over several decades and licensed to Replay. I believe that our next-generation HSV delivery platform has several distinct advantages, and the potential to be disruptive to existing viral delivery platforms. It will enable the delivery of large genes, as well as genomic genes that cannot readily be accommodated by AAV vectors. I am delighted to be able to further advance this technology with this distinguished team, who have a compelling track record of developing eye gene therapies and progressing them into the clinic.”

Professor Mark Blumenkranz, MD, Co-Founder of Eudora, added: “This is an exciting moment for retinal gene therapy, and I look forward to working with this experienced group of entrepreneurs and drug developers to advance our promising new HSV-based gene therapies into the clinic. Replay’s broad biomedical expertise and resources provide a solid foundation for Eudora’s future success.”

Professor David Schaffer, PhD, Co-Founder of Eudora, remarked: “The opportunity to increase the genetic payload that can be selectively delivered to target tissues using this next-generation HSV-1 delivery platform is intriguing. I look forward to working with the team to progress this new gene therapy modality into the clinic.”

Professor Vinit Mahajan, MD, PhD, Co-Founder of Eudora, said: "With its current ability to deliver up to eight times the payload of AAV, the University of Pittsburgh synHSV™ technology licensed to Replay offers the possibility of addressing genetic eye diseases caused by large genes and genomic genes. This will result in an increased variety of gene therapy options for patients with genetic eye diseases.”

About Eudora’s Co-Founders

Professor Joe Glorioso, PhD, is the synHSV™ Senior Advisor at Replay. He is a Professor in the Department of Microbiology and Molecular Genetics at the University of Pittsburgh School of Medicine and holds a secondary appointment in the Department of Human Genetics, University of Pittsburgh Graduate School of Public Health. He has established over a 35-year history of research related to the basic biology and genetics of herpes simplex virus (HSV). His contributions to the field include defining antiviral immune responses to infection, the genetics of viral pathogenesis and latency, and mechanisms of viral infection. Furthermore, he has been a pioneer in the design and application of HSV gene vectors for the treatment of nervous system diseases such as peripheral neuropathies, chronic pain, and brain tumors. He continues to be a worldwide leader in the HSV gene vector field through the creation of innovative gene vectors and the development of manufacturing methods for Phase I and Phase II human clinical trials for pain gene therapy. In addition to being a Founding Member of the American Society of Gene Therapy and the International Society for NeuroVirology, Dr. Glorioso is a member of the American Society for Microbiology, the American Society for Virology, Society of Neurooncology, the International Pain Society, and American Society of Cancer Research.

Professor Mark Blumenkranz, MD, is the HJ Smead Professor Emeritus in the Department of Ophthalmology at the Stanford School of Medicine. He serves as a Director of Kala Pharmaceuticals, BVI Visitec, One Medical, Iveric Bio and as the Managing Director of Lagunita Biosciences LLC. Mark co-founded, Optimedica Corporation, Peak Surgical, Adverum Biotechnologies, Verana Health and Oculeve. He was Chairman and CEO of Kedalion Therapeutics prior to its acquisition by Novartis. He founded the Retinal Fellowship Training Program at the William Beaumont Eye Institute in Royal Oak, Michigan prior to returning to Stanford where he served as Department Chair for eighteen years and the inaugural Director of the Byers Eye Institute.

Professor David Schaffer, PhD, is the Hubbard Howe Professor of Chemical and Biomolecular Engineering, Bioengineering, and Molecular and Cell Biology at the University of California, Berkeley. He serves as the Director of QB3, as well as the Director of the Bakar BioEnginuity Hub at the University of California, Berkeley. Among some of his awards are the NSF CAREER Award, AIChE Andreas Acrivos Award, and ACS Marvin Johnson Award. David was named a Technology Review Top 100 Innovator and a member of the National Academy of Inventors.

Professor Vinit Mahajan, MD, PhD, is a Professor of Ophthalmology at the Stanford School of Medicine. He is the Vice Chair for Research and directs the Molecular Surgery Program and the NIH-funded Omics Laboratory. Vinit’s team has discovered new genes for eye disease and performed the first CRISPR gene editing therapy for eye disease in human stem cells. Vinit has performed human gene therapy surgery and has developed enhanced surgeries for complex cases of retinal disease. He holds patents and has co-founded eye therapy companies that apply gene, small molecule and cell therapies to retinal disease.


About Eudora

Eudora is Replay’s first gene therapy product company. It will, in the first instance, be focused on genetic diseases of the retina. The company’s next-generation HSV-1 technology was licensed from the University of Pittsburgh, where it was developed by leading HSV specialist and entrepreneur Professor Joe Glorioso. Three of Eudora’s co-founders, Joe Glorioso, Mark Blumenkranz and David Schaffer, have previously founded publicly traded biotech companies, Oncorus, Adverum and 4D Molecular Therapeutics, respectively.

About Replay

Replay is a genome writing company, which aims to define the future of genomic medicine through reprogramming biology by writing and delivering big DNA. The Company has assembled a toolkit of disruptive platform technologies – including a high payload capacity HSV platform, a hypoimmunogenic platform, and a genome writing platform – to address the scientific challenges currently limiting clinical progress and preventing genomic medicine from realizing its full potential. The Company’s hub-and-spoke business model separates technology development within Replay from therapeutic development in product companies, which leverage the technology platforms. For example, Replay’s synHSV™ technology, a high payload capacity HSV vector capable of delivering up to 30 times the payload of AAV, is utilized by Replay’s four gene therapy product companies, bringing big DNA treatments to diseases affecting the skin, eye, brain, and muscle. The Company has, additionally, established an enzyme writing product company engaging its evolutionary inference machine learning and genome writing technology to optimize functionality. Replay is led by a world-class team of academics, entrepreneurs and industry experts.

The Company raised $55 million in seed financing in July 2022 and is supported by an international syndicate of investors that includes KKR, OMX Ventures, ARTIS Ventures, and Lansdowne Partners.

Replay is headquartered in San Diego, California, and London, UK. For further information please visit and follow us on LinkedIn and Twitter.



Dr Adrian Woolfson/Lachlan MacKinnon

Consilium Strategic Communications – Media relations

Amber Fennell/Tracy Cheung/Melissa Gardiner

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