New drugs are often tested on animals such as mice and rats before they’re tested on humans. The results of these animal studies are sometimes reported within the media, perhaps inspiring hope these “Miraculous,” “promising,” or “dramatic” discoveries will in the future be replicated in humans and result in a new drug.
But in a broadcast study Todaywe’re learning how few of these animal-tested therapies have gained approval for human use and reached the market.
Researchers from Switzerland and the UK found that only 5% of them successfully accomplished this assessment, and for those that did, the method took a mean of ten years.
This is why so few drug candidates in animal studies end up as therapies in humans.
Animal testing has its place, but it surely is flawed
Animal research will be priceless in gaining knowledge about diseases and finding possible drug targets. But they cannot fully tell us how protected and effective the treatments will likely be in humans.
For example, some potential treatments Alzheimer’s, stroke AND cancer it worked well in animals but didn’t work the identical in humans.
The authors due to this fact checked what percentage of therapies were successfully transferred from animal studies to human use, how long it took, and whether the outcomes of animal and human studies were consistent.
They did this by combining and analyzing the outcomes of studies published before August 2023, using a range of techniques.
They assessed the standard of the included studies using: meta-analysis (which mixes the outcomes of several studies) to see whether positive results from animal studies translate into positive results from human studies.
A total of 122 articles were included within the short review known as “narrative summary”, of which 62 were included within the meta-analysis.
Researchers then used a statistical technique called “survival analysis” to estimate the time it might take for the therapy to maneuver from animal studies to clinical trials and regulatory approval.
What did they find?
Overall, the researchers found that of 367 therapeutic interventions tested for 54 human diseases:
- 50% moved from animal studies to human clinical trials
- 40% progressed to randomized controlled trials (large Phase 3 clinical trials, typically required before regulatory approval)
- 5% received regulatory approval.
Their meta-analysis found that 86% of positive results from animal studies resulted in positive results from subsequent human studies.
With progressive animal research, scientists have found that on average:
- five years for animal research to succeed in the extent of any human research
- seven years to reach at a randomized, controlled trial
- ten years for regulatory approval.
Why the gap?
The authors said many animal studies weren’t well designed, making their results less reliable.
For example, most didn’t include blinding, where the investigator doesn’t know which animal received which treatment, or randomization of animals to treatment.
Many animal studies also included too few animals to offer reliable evidence of the effectiveness of the treatment.
Animal studies often involve young, healthy animals, while human patients can have multiple medical conditions and be older. Animal studies often focus on a drug’s effects on the molecular level, while human studies prioritize the drug’s overall effectiveness.
Finally, outcomes measured in animal studies don’t at all times reflect crucial clinical outcomes for patients.
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The authors suggested that if we would like to enhance drug development, researchers must focus on the standard and relevance of animal studies.
Scientists must ensure that studies are well designed, use appropriate animal models, and measure outcomes that matter to patients.
The authors also advisable greater collaboration between animal and human researchers to assist bridge the gap between preclinical and clinical research.
How nervous should we be?
The use of animals in research raises many ethical questions on the suffering and harm done to them within the name of potentially limited advantages for humans.
The high failure rate of animal research to translate into human therapies exacerbates these concerns since it calls into query the justification for using animals in research.
The discrepancy between animal and human results highlights the constraints of animal models in accurately predicting human response to drugs. This raises questions on the scientific validity of relying solely on animal data when making drug development decisions.
However, on the opposite hand, the high failure rate and high cost of animal testing has stimulated the event of alternative research methods that don’t rely on animals.
These include (laboratory) research on cells and tissues necessary to humans models, organs on a chip systems and calculations in silicon modeling involving simulation on computers.
Of course, it might be great if we didn’t need to use animals to develop medicines. However, with the increasing use of alternative methods such as computer modeling and the arrival of artificial intelligence for designing new drugs and minimizing animal testing, this will likely be in sight.