CTX001 Earns FDA’s Fast Track Status for Treating Sickle Cell Disease

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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CTX001 Phase 1/2 trial

The U.S. Food and Drug Administration (FDA) has awarded fast track status to investigational therapy CTX001 to treat sickle cell disease.

A Phase 1/2 clinical trial (NCT03745287) is recruiting patients.

CTX001 uses the CRISPR gene-editing technology to increase the production of fetal hemoglobin in patients’ red blood cells.

Fetal hemoglobin is a form of hemoglobin that naturally exists when one is born and later is replaced by the adult form of hemoglobin.

For the treatment, doctors collect a patient’s own hematopoietic stem cells (cells from the bone marrow) and modify them in the laboratory so they can produce high levels of fetal hemoglobin.

The cells are then infused back into the patient’s body where they are expected to produce large amounts of red blood cells containing fetal hemoglobin, thereby bypassing the hemoglobin deficiencies caused by sickle cell disease.

In October 2018, FDA accepted the investigational new drug application (IND) for CTX001 for treating sickle cells diseases. In April 2018, the regulatory agency had placed the IND on clinical hold until it reviewed and received answers to certain questions regarding the clinical development of CTX001.

CTX001 is currently being evaluated in an open-label, Phase 1/2 trial for adult patients, 18 to 35 years old, with severe sickle cell disease.

The trial (NCT03745287), underway in Nashville, Tennessee, is recruiting participants to evaluate the safety and effectiveness CTX001.

Participants will first undergo myeloablative chemotherapy, a strategy that kills cells in the bone marrow, thereby lowering the number of blood-forming cells, followed by a single infusion of CTX001 aimed at rebuilding a healthy bone marrow.

One of the trial’s primary (main) outcomes will be to assess the proportion of participants with an increase of 20 percent or more in the production of fetal hemoglobin, measured six months after CTX001 infusion. The increase must be maintained for more than three months at the time of analysis.

Additionally, the trial will assess CTX001’s safety by measuring the number and severity of treatment-related adverse side effects and the incidence of transplant-related mortality, among other parameters.

The fast track status should accelerate CTX001’s development and regulatory approval process. The designation is aimed at making medicines with considerable potential available to patients as soon as possible. To earn the designation, a pharmaceutical company must show that a therapy is better or safer than available treatments.

CTX001 is being developed by CRISPR Therapeutics and Vertex Pharmaceuticals as part of a research collaboration first established in 2015, aimed at discovering and developing gene editing treatments using the CRISPR technology.