Bluebird and Vertex Struggle as Sickle Cell Gene Therapy Adoption Lags

The race to cure sickle cell disease through gene therapy has not gone as its early backers hoped. Bluebird Bio, Vertex Pharmaceuticals, and CRISPR Therapeutics have all won U.S. approvals for one-time treatments. Adoption has been slow, weighed down by price tags above $2 million and a treatment process that requires chemotherapy and a stem cell transplant.

Bluebird's Zynteglo, approved in the U.S. last year, treated only a handful of patients in the first quarter. The company priced the therapy at $2.8 million per patient. Insurers and hospitals have balked at the logistics. Vertex and CRISPR's Casgevy, approved in December, uses a different gene-editing approach. It faces the same structural barriers.

"The bottleneck is not the science," said Dr. John Tisdale, a sickle cell researcher at the National Institutes of Health. "It's the delivery system. These therapies require infrastructure that most community hospitals don't have."

Bluebird's stock has fallen 60% this year. The company is exploring a sale or partnership to stay afloat, people familiar with the matter said. Vertex and CRISPR have fared better. Their shares have lagged as investors recalibrate expectations for the gene therapy market.

Curing sickle cell will take years, not months. The patients who need these therapies most are still waiting.