The potential for gene therapy treatments is huge; however drug makers are experiencing some hurdles after the lack of sales for the already launched two drugs produced to treat rare diseases.

Drug makers have expressed their difficulty in marketing new, highly expensive products for genetic diseases. According to Scientific American, European regulators have approved two gene therapies, but only three patients have so far been treated commercially.

UniQure’s Glybera, was produced to help treat a very rare blood disorder, and is currently being taken off the market due to a lack of demand. The drug costs approximately around $1 million per patient has been used only once since its approval in 2012.

Feeling the same effects, GlaxoSmithKline decided to review and potentially sell its rare diseases unit. As a result, it put the future of their Strimvelis drug in jeopardy, which was intended to help treat ADA-SCID, where sufferers are highly vulnerable to infections. Since its approval in May 2016, it has seen two sales at about $700,000.

Although the two therapies are for extremely rare conditions, GSK estimates there are only 15 new cases of ADA-SCID in Europe each year, but both drugs are expected to pave the way for much bigger products.

Hilary Thomas, KPMG, chief medical advisor, said, “It’s disappointing that so few patients have received gene therapy in Europe. It shows the business challenges and the problems faced by publicly-funded healthcare systems in dealing with a very expensive one-off treatment.”

Spark Therapuetics hopes to win US approval in January 2018 for a gene therapy to cure a rare inherited form of blindness, whereas Novartis could get a US go-ahead as early as next month for its gene-modified cell therapy against leukaemia.

Spark Chief Executive, Jeffrey Marrazzo believes there are particular reasons why Europe’s first gene therapies have sold poorly. Some of these reasons include a complex reimbursement system, Glybera’s irregular clinical trials record and the fact that Strimvelis is given at only one clinic in Italy.

He expects Spark will do better as it plans to have treatment centres in each country to address a type of blindness affecting 6,000 people around the world. Marrazzo continued to express an unclear answer as to how the firm should be rewarded for the $400 million it has spent developing the drug, given that healthcare systems would rather pay for drugs monthly rather than facing a large upfront bill.

Nevertheless, there has also been discussion associated with the possibility of some gene therapy companies requiring new business models. One suggestion was a pay-for-performance system, where governments or insurers would make payments to companies that could be halted if the drug stopped working.