Sickle cell gene therapy trial pulled before it even started

NCT ID NCT05951205

Terminated Disease control Sponsor: Vertex Pharmaceuticals Incorporated Source: ClinicalTrials.gov ↗

First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study was designed to test a single dose of exa-cel, a gene-edited cell therapy, in people with severe sickle cell disease who have the HbSC genotype. Participants would have received their own modified stem cells after chemotherapy. However, the trial was withdrawn before any patients were enrolled, so no data on safety or effectiveness were collected.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: Exa-cel (also called Exagamglogene autotemcel or CTX001), a gene-edited cell therapy made from the patient's own blood stem cells
What this could lead to: If it worked, this could provide a one-time treatment to reduce or eliminate sickle cell crises for people with the HbSC genotype.
What could go wrong: The trial was withdrawn before enrolling anyone, so no results exist. Gene-editing therapies can have serious side effects, including infertility and blood cancers, and require intensive chemotherapy beforehand.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

sickle cell disease sickle cell-hemoglobin c disease syndrome

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

SICKLE CELL DISEASE

More trials for these conditions

Other studies related to the condition(s) this trial covers.