Sticking to scientific advice from the European Medicines Agency on clinical trial design cuts the overall assessment time for a new medicine and boosts its chance of approval, an analysis of marketing authorisation outcomes has found.

The analysis - carried out by EMA staff members and its Scientific Advice Working Party, published in Nature Reviews Drug Discovery - found that two-thirds of clinical development plans submitted for scientific advice to the regulator were not suitable for purpose, and that those companies that subsequently changed their plans to fit with the recommendations were more likely to be granted approval.

An acceptable trial design at the time of scientific advice, or a change of a deficient trial design to conform with the EMA’s recommendations, increased the likelihood of a positive outcome with success rates of 84% and 86%, respectively, compared with only 41% when an inadequate design was not adapted.

Also, compliance with scientific advice on trial design was linked with a reduction in major objections raised by the Committee for Medicinal Products for Human Use during its assessment, and a 61-day shorter review period on average, “meaning that these medicines may be available to patients earlier”, the EMA said.