The platform, developed by University of Bristol spin-out Scarlet Therapeutics, has raised seed funding from Science Creates Ventures and Meltwind to build a pipeline of novel therapies to treat patients with a wide range of diseases, particularly metabolic disorders.
Therapeutic red blood cells (tRBCs) are very similar to standard red blood cells but carry additional proteins within them to provide a therapeutic benefit. Red blood cells have pervasive reach throughout the body and a long life of up to 120 days, and expressing therapeutic proteins inside the tRBCs keeps them hidden from the immune system. Previous attempts to develop therapeutic red blood cells have been hindered by the level of therapeutic proteins contained in the red blood cells, thus impacting efficacy, and the technical constraints around manufacturing these therapies. Scarlet’s technologies aim to address these issues by ensuring a high level of therapeutic proteins inside the tRBCs, enabling more efficacious and thus effective therapies and improving the manufacturing by being able to generate the tRBCs from cell lines rather than from donated stem cells.
Scarlet is initially targeting two rare metabolic diseases hyperammonemia and hyperoxaluria. Hyperammonemia is where patients can’t remove toxic ammonia from their system, leading to a range of neurological symptoms and, in severe cases, life-threatening complications. Urea cycle disorders, one of the causes of hyperammonemia, occur in one in 250,000 live births in the US and one in 440,000 live births internationally. For people in the US with urea cycle disorders, there is an 11-year survival rate of around 35% for those who develop hyperammonemia early in life.
Hyperoxaluria is a condition where there is too much oxalate in the urine and is either caused by a rare inherited disorder of the liver (primary hyperoxaluria) or where excess oxalate is absorbed into the gastrointestinal tract and then excreted in the urine (secondary hyperoxaluria). It can also be caused by severe liver diseases such as cirrhosis.
The platform also has the potential to treat other metabolic diseases requiring enzyme replacement therapy, as well as cancer and autoimmune diseases.