A study has been released by the USA's Biotechnology Industry Organization which shows the overall success rate for drugs moving through clinical trials to approval in the country from late 2003 to the end of 2010 is now down to nearly one in 10.

This compares to previous reports which showed the rate of drug approvals is one in five to one in six. However BIO says this latest analysis builds on those findings and uses "a broader, deeper and larger sample" of clinical trials and approvals data using the BioMedTracker (BMT) database of "4,500 drugs and over 8,000 unique development paths".

Using data from the past seven years, the study notes that overall success rates from Phase I to approval by the Food and Drug Administration is nearly 9%, comprising lead and secondary indications. When separated, lead indications have close to a one in seven rate of approval and secondary comes in at one in 30.

The study also shows that large molecule drugs are twice as successful in gaining approval than small molecule treatments. "We believe that this study provides the market with an accurate and comprehensive picture of the relative difficulty of achieving product approval in the USA" said Michael Hay, senior biotechnology analyst at BMT.

He added that "strikingly, oncology drugs have the toughest time making their way through the clinic, despite cancer being the most closely studied area in drug development".