FDA puts Vertex, CRISPR sickle cell trial on hold

Vertex Pharma
CRISPR and Vertex’s problems with the FDA haven’t spilled over into a delay in Europe. (Vertex Pharmaceuticals)

The FDA has placed a clinical hold on Vertex and CRISPR Therapeutics’ sickle cell disease candidate. Shares in CRISPR fell 15% as investors digested the delay to the start of the gene-editing startup’s first U.S. clinical trial.

CRISPR and Vertex filed to run a U.S. phase 1/2 trial in adults with sickle cell disease last month with a view to starting the study later this year. That target may now be in jeopardy, although the lack of details shared by CRISPR and Vertex to date means the impact of the clinical hold on autologous gene-edited hematopoietic stem cell therapy CTX001 is unclear.

In a note to investors, Jefferies analyst Michael Yee said Vertex is also in the dark. The biotech expects to receive minutes from the FDA and other information in the coming weeks, at which point it will have a clearer idea of what it will take to get back on track.

The lack of clarity means the clinical hold could be anything from a bureaucratic holdup to a more substantial concern about the gene-edited cells. Yee thinks the hold is likely “more about information requests and additional background data versus anything too arduous.” But CRISPR investors reacted edgily, wiping 15% off a stock that has been on a triple-digit tear in recent months. 

CRISPR and Vertex’s problems with the FDA haven’t spilled over into a delay in Europe, where they are still in with a shot of dosing beta-thalassemia patients with CTX001 this year. 

The partners’ exploration of CTX001 in sickle cell and beta-thalassemia reflects the role the beta-globin gene plays in both diseases. CRISPR thinks taking cells from patients and using gene-editing tools to disrupt their genetics will lead to red blood cells that have enough fetal hemoglobin to improve outcomes.

Vertex bought into the idea late last year when it picked CTX001 as the first codevelopment project in its collaboration with CRISPR. Vertex paid $105 million upfront in 2015 to enter into the collaboration.