Personalised cancer medicine: the path of knowledge
The epoch to sequence the human genome for just $1,000 has finally arrived. Rapid, low cost and more accurate DNA sequencing technologies will undoubtedly continue to revolutionise biomedical research and clinical practice. The most exciting applications are obviously in disease genetics, and particularly in personalised medicine. In the coming decades, profiling a patient’s individual genome is expected to play a crucial role in preventing, detecting, understanding and treating complex diseases that were otherwise difficult to diagnose.
Many clinical oncology specialists would agree that a personalised approach to cancer offers the potential to change current treatment and care of the disease from reactive to proactive. The rationale behind personalised cancer medicine is earlier diagnosis, more efficient drug development and more effective treatments tailored to target the biological characteristics of an individual’s tumour 1. In addition to the traditional classification of cancers, based on where they are located in the body and what they look like under the microscope, a molecular stratification approach will be employed. The will allow for the grouping and selection of individual cancers for optimal therapy according to their molecular diversity (“biotype”), which is believed to improve survival rates for many types of cancer 2. Current advances in personalised medicine represent the summit of 40 years of basic cancer research. Notable paradigms of implementation of this stratified platform in clinical oncology practice include breast cancer, lung cancer, melanoma and blood cancer owing in large part to the development of targeted therapeutic strategies. One of the earliest and most exciting applications of personalised medicine came from drug Trastuzumab. About 25%-30% of patients with breast cancer have a genetic defect associated with abnormal high levels of a protein called Her2 who are unresponsive to standard chemotherapy. Trastuzumab was approved for patients with HER2 positive tumours in 1998 and further research in 2005 showed that it reduced tumour recurrence by 52% in combination with other chemotherapies 3.
The advantages of profiling cancer patients are manifold. Stratified oncology efforts have already shown some improvements on both biomedical and clinical research with the potential to grow bigger as we expand our understanding of the underlying molecular mechanisms of the disease. Avoiding unnecessary ineffective therapies so that the right drug is given to the right patient at the right time will improve patient survival expenses and may substantially reduce healthcare expenses. At an individual level stratification gives patients greater confidence in the treatment outcome, peace of mind (also known as value of knowing) and more importantly minimises chemotherapy side effects in non-responsive patients. For clinical trial design a smaller number of individuals will need to be recruited (due to the higher number of responders) which will significantly reduce costs and speed up the drug licensing process.
As the cost of next generation sequencing continues to drop, simultaneous characterisation of a patient’s genome will provide clinicians with a multitude of information upon which to make diagnosis and treatment decisions. The highly standardised nature of DNA sequence will allow for the development of comprehensive catalogues of genetic variations and their association with different diseases. Hence, it is quite foreseeable that genetic cancer biomarkers will become day routine for choosing optimal drugs and treatments, avoiding adverse side effects and also for identifying patients at the greatest risk 4. In order to successfully advance the rapid translation of clinical research into the clinic, strong collaborative links between academia, public institutions, industry and healthcare systems, often across countries are fundamental. The hope is that in the future this will make it possible to already identify patients who are most likely to benefit from a new therapeutic drug in time for clinical trials. The personalised medicine approach and the parallel development of targeted therapies, has already started to extent its applications outside the field of oncology, since, there too, the individualised approach seems to offer good prospects of improving patient outcomes. Personalised medicine requires fundamental transformation in the way we traditionally perceive and diagnose disease. A more scientific driven approach to disease diagnosis and classification will ultimately lead to the right treatment for subgroups of patients who share certain characteristics.
- Trusheim MR, Berndt ER, Douglas FL. Stratified medicine: strategic and economic implications of combining drugs and clinical biomarkers. Nature reviews Drug discovery. 2007
- Palanisamy et al. Rearrangements of the RAF kinase pathway in prostate cancer, gastric cancer and melanoma. Nature medicine. 2010
- Piccart-Gebhart MJ et al. Trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer. The New England journal of medicine. 2005
- Green ED, Guyer MS. Charting a course for genomic medicine from base pairs to bedside. Nature. 2011