Correctsequence Therapeutics’ Gene-Editing Therapy Shows Promise in Sickle Cell Disease Patient

SHANGHAI, CHINA – August 26, 2025 — In a landmark announcement, CorrectSequence Therapeutics (Correctseq) has reported the first successful treatment of a sickle cell disease (SCD) patient using its high-precision base-editing therapy, CS-101. The clinical breakthrough, achieved in collaboration with the First Affiliated Hospital of Guangxi Medical University, marks the first reported clinical cure of SCD in China using this technology.

The patient, a 21-year-old woman from Nigeria who previously suffered from recurrent and painful vaso-occlusive crises (VOCs), has remained crisis-free and in good health for six months following treatment. Her remarkable recovery highlights the potential of base editing to provide a definitive cure for this debilitating genetic disorder.

A New Hope for Hemoglobinopathies

Sickle cell disease is one of the most common single-gene disorders globally, affecting an estimated 300,000 infants born each year. It’s caused by a mutation in the beta-globin gene, which leads to abnormal, sickle-shaped red blood cells. These cells get stuck in blood vessels, causing chronic pain, anemia, and organ damage. Current treatments often only manage symptoms, while the only curative option—hematopoietic stem cell transplantation (HSCT)—is limited by the need for a matched donor.

CS-101 offers a new, patient-specific approach. It uses transformer Base Editing (tBE) technology to precisely modify a patient’s own hematopoietic stem cells. The therapy targets a regulatory element of the gamma-globin genes (HBG1/2), mimicking natural mutations that cause hereditary persistence of fetal hemoglobin (HPFH). This genetic change reactivates the production of fetal hemoglobin (HbF), which is healthy and prevents the sickling of red blood cells.

Patient’s Dramatic Improvement

Following the CS-101 infusion in February 2025, the patient experienced rapid hematopoietic recovery. Her neutrophil and platelet counts returned to normal within weeks. Her HbF levels, which were initially at 4.4%, soared to over 60% within three months and have remained stable. Simultaneously, her sickle hemoglobin (HbS) levels dropped, leading to a stable HbF-to-HbS ratio of 6.5:3.5. Most importantly, she has not experienced any VOCs or treatment-related adverse events during the six-month follow-up. Her total hemoglobin levels have consistently been above 120 g/L, a significant improvement from her baseline of 67.3 g/L.

A Safer and More Effective Alternative

Correctseq’s tBE platform is designed to be more precise than conventional CRISPR/Cas9-based therapies. The company notes that CS-101 achieves a higher HbF-to-HbS ratio and faster hematopoietic recovery without the risks of large DNA deletions or chromosomal rearrangements. The first beta-thalassemia patient treated with CS-101 has remained transfusion-free for over 22 months, further bolstering the therapy’s promise as a potential best-in-class treatment for hemoglobinopathies.

With a completed Phase I trial for beta-thalassemia and a successful first SCD patient, Correctseq is now preparing to launch pivotal Phase II/III trials for both diseases. Global recruitment is underway, with the company aiming to make this first-in-class, China-originated gene-editing therapy accessible to patients worldwide.