martes, 5 de junio de 2018

What is Personalized Medicine?

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By Hannah Simmons, BSc

Each patient is unique, with a different lifestyle, environment and DNA. Therefore, the “one size fits all” procedures which are typically used for diagnosing and treating medical conditions have limited effectiveness, as each disease affects each patient differently.

Image Credit: enzozo / Shutterstock

Personalized medicine uses the analysis of genetic information to improve the treatment and even prevention of disease, particularly aiding risk assessment, detection, diagnosis and treatment management of disease.

Genome-wide association studies (GWAS) have allowed the identification of specific genes which are related to specific diseases. These studies analyse small variations in DNA, called single nucleotide polymorphisms (SNPs), which are more common in patients with the disease compared to the general popilation.

Diagnosis and treatment of disease

As previously discussed, the use of GWAS can aid the accurate diagnosis of diseases through SNP screening. Additionally, this genetic information can also be applied to investigate how a patient will respond to a specific medication, ensuring that prescribed treatments are both safe and effective.

Through genome analysis, highly specific and targeted medicines can be prescribed which are more effective in the treatment of a specific form of disease.

For example, this personalization of treatment has been applied within breast cancer therapy. Around 30% of patients with breast cancer have a mutation within their genome which leads to an over-expression of the gene HER2.

This mutation makes this cancer highly resistant to traditional treatments, reducing the prognosis of the patient. Through genetic sequencing, this mutation can be identified and specific treatments can be applied. For example, one monoclonal antibody has been shown to reduce the rate of recurrence of breast cancer by 52% in patients with this mutation, when combined with chemotherapy.

Disease prevention

Another application of personalized medication is disease prevention. Genomic screening allows the production of genetic profiles, which identify genetic predisposition to certain diseases.

Therefore, this allows early prevention of disease, such as changes in lifestyles and preventative medications. Overall, this method could help to reduce the risk of disease in many patients, improving prognosis and reducing the burden of disease.

Histopathology

Finally, personalized medication is also useful within the field of tissue typing. For example, traditional heart transplantation typing requires a highly invasive heart biopsy, to identify which donor heart will have the smallest chance of rejection.

However, with the development of genetic testing methods, a very non-invasive blood test can be carried out instead. This detects the possibility of rejection, increasing the chances of success and ensuring the safety of the patient.

Drug development

Another field that utilizes personalized medicine techniques is the development of drugs. Identification of patients with specific genetic profiles allows testing of new targeted treatments, ensuring that the development of drugs is faster due to increased clinical trial success. This could therefore help the development of treatments for diseases which do not currently have viable therapy options.

Oncology

The application of personalized medicine in cancer allows the classification of tumours dependent upon specific mutations, rather than location, making treatment and diagnosis much more effective. This also allows the detection of cancers very early, due to genetic markers.

One example of personalized medicine application within cancer is the treatment and detection of melanoma. One mutation which can lead to this cancer is the mutation of the B-raf protein, which sends signals to cells instructing them to grow.

Through detection of this mutation, specific treatments can be applied which increase the prognosis of the patient significantly. For example, one monoclonal antibody inhibits this mutated B-raf, and therefore prevents the abnormal cell growth. However, this treatment is only effective in patients with the B-raf mutation. Genetic sequencing allows the identification of patients which can benefit from this therapy option.

Personalized medicine aims to revolutionize medicine, increasing the effectiveness and targeting of treatments, increasing the speed of drug development and overall functioning to increase the prognosis of patients in many different fields, such as cancer.

Reviewed by Chloe Barnett, BSc