The latest annual report from Trinity Partners has found that orphan disease drugs often perform poorly at launch and continue to underachieve after three years of sales. At the other end of the spectrum, the most successful drugs on the market were for non-orphan diseases such as cancer and HIV.

Trinity Partners’ report ranked the 57 new drugs approved in 2015 in the US based on therapeutic benefits, commercial sales and research and development costs. Oncology was the area with the greatest number of approved drugs, standing at 30% in 2015.

Most ultra-orphan products, such as Kanuma for lysosomal acid lipase deficiency, had lower commercial performance, though some such as Orkambi for cystic fibrosis and Strensiq for hypophosphatasia did perform better than average.

According to the report, the ten most expensive drugs approved between 2014 and 2016 were all for orphan diseases. This comes, it says, as increased pricing pressures and greater competition are forcing drug companies to be more strategic.