I came of age scientifically at the beginning of the cloning era. As various genes associated with human genetic disorders—sickle cell disease, cystic fibrosis, muscular dystrophy, Huntington’s—were cloned, the papers reporting these successes always ended with some statement that now the door was open to therapy. These prophecies proved to be wildly optimistic.

Now, with the advent of CRISPR gene editing, it is becoming possible to realize the potential for gene therapies, at least for some diseases. There are dozens of clinical trials underway to pursue such therapies for some of these diseases. However, for rare and orphan diseases, these therapies are often not being pursued.

Rare diseases are diseases that affects less than 200,000 Americans. Orphan diseases, including rare diseases, are neglected conditions whose treatments are often not considered profitable due to their cost to develop and limited patient population.

Wiskott-Aldrich syndrome is due to a mutation that leads to immune and clotting defects. As a blood disorder, it represents a particularly attractive target for gene therapy, since hematopoietic stem cells are relatively easy to harvest from affected patients, and could be edited and reintroduced successfully with no problems of graft rejection:

“For a while, it seemed gene therapy for Wiskott-Aldrich was on track for wider availability. Genethon, a French nonprofit research organization, sponsored promising clinical trials but didn’t have funding to continue development, CEO Frédéric Revah, PhD, said.

“Drugmaker GlaxoSmithKline transferred another therapy to Orchard, which announced in 2019 that it had secured a designation from the FDA meant to speed up development and review. But Orchard discontinued investment in this and two other rare-disease treatments a couple of years ago, with CEO Bobby Gaspar, MD, PhD, saying the company sympathized with affected families and would look for other ways to advance the therapies.

“”There’s a huge number of diseases out there that could benefit from gene therapy but for which there is no profitability model because the investment for research is high, the cost of production is high, and the number of patients is very low,” Revah said.”

Once, the barrier to gene therapy was identification and characterization of the relevant gene and its mutations. Then, it was finding a strategy to correct the defect at therapeutic levels. But now, the barrier is economics. Who will pay for the development of therapies that can’t be justified on corporate spreadsheets?

Drug makers lack incentives to cure rare diseases