Gates Foundation to invest in Tessera SCD gene-editing treatment
Foundation to invest up to $50 million to support development, company says
The Bill and Melinda Gates Foundation is investing up to $50 million in Tessera Therapeutics to support the development of a new gene-editing medicine for sickle cell disease (SCD), the company said.
“We look forward to advancing a genetic medicine that can potentially reshape the treatment landscape for sickle cell disease worldwide,” Michael Severino, MD, Tessera’s CEO, said in a company press release.
SCD is caused by mutations in a gene that provides instructions for making hemoglobin, the protein that red blood cells use to carry oxygen throughout the body. The mutated hemoglobin protein tends to clump inside cells, deforming them and making them prone to getting destroyed prematurely and obstructing blood vessels.
Gene editing is a type of technology that is used to alter a cell’s genetic code. In SCD, gene-editing therapies aim to change the genetic code of hematopoietic stem cells (HSCs), stem cells found in the bone marrow that are responsible for making all types of blood cells.
The first gene-editing therapy for sickle cell, Casgevy (exagamglogene autotemcel), which was developed by CRISPR Therapeutics and Vertex Pharmaceuticals, was approved in the U.S. in December 2023 to treat SCD patients ages 12 and older. It’s also been conditionally authorized in the European Union and the U.K.
A new approach
During Casgevy treatment, HSCs are collected from a patient’s bone marrow, taken to a lab to undergo gene editing, and then returned to the body via a stem cell transplant.
Tessera takes a new approach. The company’s proprietary Gene Writing technology aims to create an in vivo therapy in which the gene editing would occur inside the body, which in theory could eliminate the need for stem cell transplant.
Casgevy uses the CRISPR/Cas9 gene editing tool to alter the genetic code of HSCs so that cells will be able to produce an alternative form of hemoglobin called fetal hemoglobin, which is normally only made during fetal development. This alternative version of the protein is more efficient at transporting oxygen than its adult counterpart and can help mitigate the harmful effects of the mutated adult version of hemoglobin in people with sickle cell.
The process of collecting HSCs and editing them outside the body is referred to as an ex vivo approach. Tessera’s in vivo therapy, which would alter the genetic code of HSCs while they are in the body, could mean the patient wouldn’t need to undergo an invasive, risky stem-cell transplant.
Tessera’s therapy also differs from Casgevy in that it aims to directly correct the mutation that causes sickle cell, rather than boosting the production of fetal hemoglobin.
“Sickle cell disease patients globally remain deeply underserved by existing treatment options,” Severino said. “We are excited to develop what we believe will be a disruptive one-time curative treatment for SCD that is safer, easier, and more scalable than ex vivo genetic approaches.”
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