Chinese gene therapy clinically cures patient with serious blood disorder

The Chinese company CorrectSequence Therapeutics announced that it managed to clinically cure a teenager who suffered from transfusion-dependent beta thalassemia, a serious blood disease, through a treatment based on gene editing developed by them, reports South China Morning Post.

Beta thalassemia is an inherited blood disorder that reduces the production of hemoglobin, a blood protein that is responsible for transporting oxygen from the lungs to the rest of the body. Low hemoglobin levels can mainly cause anemia and fatigue.

However, people who suffer from the more serious variant of this condition, known as ‘transfusion-dependent beta thalassemia’, have to periodically receive blood from a donor to control their symptoms. Thalassemia is part of a group of the world’s most common monogenic disorders known as ‘haemoglobinopathies’. It has been documented that 400,000 children are born with these conditions each year.

The first successful cure of a serious illness

CorrectSequence detailed the case of a teenager who had been receiving transfusions twice a month since he was 2 years old, before starting the gene treatment called ‘CS-101’. Likewise, he commented that, after 8 weeks of receiving the therapy, an increase in fetal hemoglobin (HbF) levels was observed by around 95 grams per liter, which represents almost 81% of total hemoglobin.

The Shanghai-based company considered the CS-101 trial successful, since the teenager had not needed blood transfusions for more than 2 months. “In particular, to our knowledge, this is the first global report on the successful clinical cure of hemoglobinopathy with base editing therapy,” he said.

To develop CS-101, an innovative transformer base editing technology was used, which allows editing of individual DNA base pairs without the need to break the double strand. “CS-101 does not pose safety risks, such as deletions of large DNA fragments, chromosomal rearrangements or off-target mutations,” CorrectSequence said.

According to SCMP, CS-101 is not the first gene therapy used to treat hemoglobinopathies, as a treatment using CRISPR/Cas9 gene editing technology had previously been approved in the UK and US. called ‘Casgevy’. However, compared to therapies using CRISPR/Cas9, CS-101 allows patients to stop receiving transfusions sooner, given the increase in normal hemoglobin levels.

Thalassemia International Federation (TIF) director Androulla Eleftheriou emphasized that CS-101 “greatly improves the safety of the approach compared to other advanced therapy applications.” However, she highlighted that there are still challenges related to gene therapies, including possible long-term side effects and “the possibility that the cure may not be permanent.”

The Cleveland Clinic mentioned that most people with beta thalassemia live in Africa, the Mediterranean, the Middle East, India, and Southeast Asia. On the other hand, the Comprehensive Thalassemia Center of Northern California stressed that this is one of the most common hereditary diseases in China, with people originally from the south of the Asian country being the ones at greatest risk of suffering from it. With RT

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