According to an analysis from the Institute for Clinical and Economic Research (ICER), the price tag for a new medicine which treats a genetic form of childhood blindness should be at least 75 percent lower based on its cost effectiveness.

ICER’s chief medical officer, David Rind, MD, MSc, said considering the lack of data that Luxturna, the gene therapy developed by Spark Therapuetics, permanently improves vision in children with biallelic RPE65-mediated retinal disease, the price should be between $153,000 to $217,000. Instead, the list price is $850,000.

“Assuming a 10- to 20-year period of benefit, at list price the treatment does not meet standard cost-effectiveness thresholds, even after accounting for the broader societal benefits improved vision has on productivity and education cost,” Rind said in a statement. “The cost-effectiveness findings move into standard ranges only in analyses that consider these non-medical benefits while also assuming that only younger patients with the best baseline vision receive treatment.”

This form of blindness affects less than 2,000 people in the U.S., according to report. ICER didn’t dispute that the therapy has benefits, saying it “clearly improves vision for patient over several years,” describing it as “a scientific milestone” as the first gene therapy approved in the U.S. that inserts a new working copy of a gene into the cells of a patient with a genetic disorder.

The report also noted while visual field improvements were seen with the therapy, slight declines in the results began at three years. Additionally, the results of quality of life measures collected during studies of Luxturna haven’t been released, and Spark stated they were “unable to provide that data.”

“The high cost makes this unlikely to be a cost-effective intervention at commonly used cost-effectiveness thresholds, except for the younger population from a modified societal perspective,” the report concluded. “However, for ultra-rare diseases, decision-makers in the US and in international settings often give special weighting to other benefits and to contextual considerations that lead to coverage and funding decisions at higher prices, and thus higher cost-effectiveness ratios, than applied to decisions about other treatments.”

Approved by the Food and Drug Administration in Dec. 2017, Luxturna is scheduled to be launched in March.