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High-Precision Base Editing Clinical Treatment for Sickle Cell Disease -- CorrectSequence Therapeutics' CS-101 Achieves Promising Results in First Patient
Picture: The patient, a 21-year-old woman from Nigeria , had previously suffered from recurrent VOCs. For six months after receiving CS-101, she remains crisis-free and in good health.
Hemoglobinopathies — including SCD and β-thalassemia (β-thal) — are the world's most common group of monogenic diseases, with approximately 7% of the global population carrying a pathogenic variant. Each year, around 400,000 newborns are affected. SCD, caused by mutations in the β-globin gene, leads to abnormal, sickle-shaped red blood cells, resulting in chronic anemia, recurrent pain crises, increased infection risk, and progressive organ damage. Globally, about 3.5% of the population carries the sickle mutation, with roughly 300,000 affected infants born annually, especially in
Africa , the Mediterranean, the Middle East , and
South Asia .
Existing treatments such as symptomatic drugs and blood transfusions can alleviate symptoms but do not offer a cure. Hematopoietic stem cell transplantation (HSCT) can be curative, but the requirement for a matched donor limits accessibility. Gene-editing approaches, particularly base editing, can activate fetal hemoglobin in a patient's own blood cells — eliminating the need for a donor and offering a shorter, potentially safer treatment path.
CS-101 is a gene-editing therapy based on the high-precision transformer Base Editor (tBE) platform (Wang
., , 2021), developed by Correctseq's scientific co-founders. The therapy targets β-hemoglobinopathies by precisely modifying a regulatory element in the promoter of the γ-globin genes ( ), mimicking naturally occurring single-nucleotide variants found in individuals with hereditary persistence of fetal hemoglobin. This reactivates γ-globin expression to produce functional HbF, which prevents sickling and reduces hemolysis.
In the IIT, the patient began with a baseline hemoglobin level of 67.3 g/L. Following CS-101 treatment in February 2025 , she achieved rapid hematopoietic recovery, with neutrophil engraftment in 13 days and platelet counts surpassing 50×10⁹/L in 21 days. Her HbF levels rose from 4.4% to 34.6% within one month, and since the third month post-treatment, HbF levels have remained above 60% while HbS has stayed below 40%. No VOCs or treatment-related adverse events have been reported.
Compared with conventional CRISPR/Cas9-based therapies, CS-101 delivers efficient hematopoietic recovery and higher HbF-to-HbS ratio, without the risks of large DNA deletions, chromosomal rearrangements, or off-target mutations.
To date, CS-101 has been used to treat nearly 20 patients with β-thalassemia or SCD in clinical trials. The first β-thalassemia patient treated has remained transfusion-free for over 22 months. This positions CS-101 as a potential best-in-class gene-editing therapy — and the world's first base editing treatment — for β-hemoglobinopathies.
The Phase I trial of CS-101 for β-thalassemia has been completed, with all patients achieving transfusion independence. Pivotal Phase II/III trials are set to begin soon, and global recruitment for both SCD and β-thalassemia trials is now underway. Correctseq is committed to advancing CS-101 — a first-in-class,
China -originated gene-editing therapy — to deliver safe, effective, and accessible treatments for patients worldwide living with severe hemoglobin disorders.
CorrectSequence Therapeutics (Correctseq), incubated at ShanghaiTech University, is dedicated to leveraging innovative gene-editing technologies to transform the lives of people with severe diseases. The company has developed multiple state-of-the-art base-editing systems that offer exceptional precision, minimize off-target effects, and enhance editing efficiency. Correctseq's mission is to discover, develop, manufacture, and commercialize curative genetic medicines across a broad range of conditions. Its robust pipeline spans genetic disorders, metabolic diseases, and cardiovascular conditions, with several programs already advancing toward clinical development.
For more information, visit .
The First Affiliated Hospital of Guangxi Medical University, ShanghaiTech University, Shanghai Clinical Research and Trial Center.
Media Contact:
Business Cooperate: BD@correctsequence.com
Clinical Trial Recruitment: CT@correctsequence.com
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