Developing high payload delivery technology

The 152kb payload of HSV enables a significant number of gene therapy targets. Our pipeline encompasses the delivery of big cDNAs, multiple genes, and "genomic" genes, including the full regulatory sequences.
Replay Bio Construct Illustration

Clinical product pipeline

GroupTargetProgramStudy populationCassette sizeDiscovery 1Discovery 2IND-EnablingPhase 1Phase 2
TCR-NK cell therapyPRAMESY-307Basket study10.1kbDoneProduct: SyenaDoneProduct: SyenaPendingProduct: SyenaTo doProduct: SyenaTo doProduct: Syena
NY-ESO-1SY-104Sarcoma10.1kbDoneProduct: SyenaDoneProduct: SyenaDoneProduct: SyenaPendingProduct: SyenaTo doProduct: Syena
NY-ESO-1SY-104Multiple Myeloma10.1kbDoneProduct: SyenaDoneProduct: SyenaDoneProduct: SyenaPendingProduct: SyenaTo doProduct: Syena
High payload HSV gene therapyABCA4ED-001Stargardt7.2kbDoneProduct: EudoraPendingProduct: EudoraTo doProduct: EudoraTo doProduct: EudoraTo doProduct: Eudora
COL7ATL-001Dystrophic Epidermolysis Bullosa19.2kbDoneProduct: TelariaPendingProduct: TelariaTo doProduct: TelariaTo doProduct: TelariaTo doProduct: Telaria

synHSV™ Big DNA eye gene therapy

Stargardt disease is a genetic eye disease that causes retinal degeneration and vision loss. It is the most common form of inherited macular degeneration, affecting about 30,000 people in the U.S. The progressive vision loss is caused by the degeneration of photoreceptor cells in the central portion of the retina called the macula.


synHSV™ Big DNA skin gene therapy

Dystrophic Epidermolysis Bullosa causes the skin to be fragile and blister easily. Blisters and skin erosions form in response to minor injury or friction, such as rubbing or scratching. Severe cases of this condition involve widespread blistering that may lead to vision loss, scarring, and other serious medical problems.



Building on technologies developed at MD Anderson and Replay, TCR-NKs have the potential to provide the next generation of cell therapy, combining the safety, efficacy, and scalability of cord blood derived NK cells with the ability of TCRs to target intracellular tumor neoantigens. The cell therapy platform is based upon the scientific discoveries of Katy Rezvani, M.D., Ph.D., professor of Stem Cell Transplantation & Cellular Therapy at MD Anderson.


NY-ESO-1 (New York Esophageal Squamous cell carcinOma 1) is a highly validated tumor target neoantigen with aberrant expression in numerous cancer cell types, including myxoid/round cell liposarcoma (89%), Neuroblastoma (82%), Synovial Sarcoma (80%) and Multiple Myeloma (60%). Its ability to elicit spontaneous humoral and cellular immune responses, together with its restricted expression pattern, have established it as a compelling target for cancer immunotherapy.

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