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Drug success rate falls to 1 in 20

Beware the ‘wonder drug proceeds to human trials based on animal studies’ story! Sadly, today the chances of such a drug proceeding much further along the development pipeline are now only 5%.

Several recent reports by the drug industry have shown that the approval rate of new drugs is getting worse. The most recent study of new drugs approved between 2007 and 2011 has shown that the failure rate is now 95%, an all-time low.

New medicines have to go through a series of human (clinical) trials that utilise increasing numbers of people before they are approved by drug regulatory authorities. Drugs first enter phase I human trials traditionally after tests on animals have apparently shown that they are safe and work. Only after successful phase III trials in humans is a drug approved for use by patients.

We used to quote success rates from a report by the FDA in 2004 that showed that a new medical entity - a genuinely new drug- had only an 8% chance of being approved after entering clinical trials.(1) This statistic was a damning indictment of the ability of animal tests to predict effects in humans. However, more recent data from the drug industry has shown that this success rate is declining:

  • One US survey of 4,451 drugs made by 835 companies between 2003 and 2011 found that only 7.5% of new medical entities were approved by the FDA after entering the first phase of clinical trials. (2) Cancer drugs (new and existing) were shown to have the lowest success rate (6.7%) followed by those for heart disease (7.1%), and psychiatric disorders (9.4%). The authors themselves admitted that “current animal models [of cancer] can be poor predictors of clinical outcomes in humans”.
  • Data collected from 2006-2008 by CMR International from 14 drug companies reported a success rate of 5% (3).
  • More recent data obtained from 13 large pharmaceutical companies for approvals made between 2007 and 2011 found the success rate after entering phase I trials was 5%. (4)

In 2013 only 27 new drugs were approved by the FDA (the yearly average over the last five years is 28) (5).

The importance of these statistics is that we are told that animals are used to show that drugs are safe and work in humans. The biggest drug failures are in phase II trials where the drug is tested to see if it works, as well as continuing to look at safety, which use only a few hundred patients (3). “The weakest link in the chain was, and still is, in Phase II, where around 50% of failures are typically due to efficacy, 30% are due to strategic reasons and 20% are due to safety concerns”. If tests on animals cannot predict effects in a few hundred people then clearly they are not working.

Sadly, because companies know that they have to rely on animal data to get a drug past the regulators they do not invest as much time, money and confidence in high tech, non animal methods as they can - and should - be doing.

We should all be very concerned that drug approval rates are so low. Not only is the industry destroying millions of animal lives but time and money is being wasted on drugs that do not work while patients continue to suffer.





2. Clinical development success rates for investigational drugs. (2014). Nature Biotechnology, 32(1): 40-51. Original article can be found here:

3. Arrowsmith, J. 2012. A decade of change. Nature Reviews Drug Discovery 11, 17-18.

4. KMR Group Inc. Annual R&D General Metrics Study Highlights New Success Rate and Cycle Time Data CHICAGO, Illinois, August 8, 2012)

5. Seven days: 3–9 January 2014. Nature 9 Jan 2014, 505, 136.