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Elevated mRNA for transformative medicines.
ParcelBio is engineering a new class of mRNA medicines designed to deliver unprecedented potency and durability. Its proprietary APEXm™ platform uses novel RNA domains to enhance protein expression and extend activity, enabling therapies that reach the thresholds required for meaningful, and potentially curative, clinical outcomes. The company is advancing programs in autoimmune disease, oncology, and encoded protein therapeutics.
ParcelBio offers a next-generation mRNA platform called APEXm™ that enables higher potency and longer durability of protein expression for therapeutic applications. Their approach aims to reprogram immune cells, enhance oncology therapies, and enable programmable delivery of diverse therapeutic proteins.
The APEXm™ platform uses proprietary RNA domains to recruit the cell's native stabilizing machinery, driving higher and longer-lasting expression of encoded proteins. It is described as a modular, universal architecture that can enhance expression of any encoded protein across multiple target cell types. The pipeline highlights in vivo CAR-T approaches for autoimmune disease and oncology, with the ability to tune potency, duration, and dosing for different cancer biology and enable durable protein production for therapeutic proteins.
Who it’s for: Biotech and pharmaceutical developers, particularly those working on RNA therapeutics, CAR-T and immune-oncology, and developers seeking durable in vivo mRNA expression for programmable protein therapies.
Funding mentions (Breyer Capital, Y Combinator, General Catalyst) and press coverage; early-stage/financing activity as of May 2026.
David is the co-founder and CEO of ParcelBio. He was previously VP of RNA Platform at Orbital Therapeutics / Circ Bio, where he led the development of a circular RNA therapeutics platform. Before that, he was Sr. Director of Molecular Research at Freenome, where he built the multiomics diagnostics platform that enabled a blood test for the early detection of cancer. David obtained his PhD from MIT, was a UCSF Faculty Fellow, and has been honored with Forbes ‘30 Under 30’ and an NIH DP5 Award.
Chris is the co-founder and CSO of ParcelBio. He was previously a scientist at Orbital Therapeutics, where he was the primary contributor on multiple patents regarding stabilization of therapeutic RNAs. Chris obtained his PhD from UCSF where he studied RNA packaging and protection in viruses.
Formerly “Parcel Therapuetics”, “Parcel Therapeutics” · why startups rename →
Unlocking the next generation of mRNA medicines
Using the immune system to cure disease
