Molecular Profiling and Companion Diagnostics: Where is Personalized Medicine in Cancer Heading?

Mukesh Verma


Personalized Medicine. 2014;11(8):761-771. 

In This Article

Current Status of Personalized Medicine & Cancer

Personalized medicine is an emerging science with the potential to improve early cancer diagnosis and enable the development of treatment based on an individual's genetic background, family history and other characteristics.[1] The number of publications in the field of personalized medicine reflects the interest in this field. As shown in Table 1, as of January 2014 there were more than 4600 publications on personalized medicine in cancer. The private sector sees potential in this area and has significantly increased investments in it during recent years.[2] Identifying patients who may benefit from personalized therapy depends on identifying accurate assays for the biomarkers that are needed to determine optimal treatment. Several cancer biomarkers identified to date are useful in early cancer detection or in selecting patients for treatment (via screening). This review addresses personalized medicine as a whole but focus is on cancer.

As personalized medicine becomes more popular and commonplace, those who pay for the treatment are affected. For insurance companies, providing healthcare is more expensive when more tests are performed to diagnose a disease and when customized treatment is used. In the long term, personalized medicine will be beneficial because information about individuals' diseases and responses to different interventions and treatments will become available and will facilitate the development of disease-prevention approaches.[3] Well-tested drugs have been determined to produce different responses in genetically different individuals, and scientists and others have realized the significance of this area of research. Clinicians and researchers have come together through clinical trials and consortia (such as the International Cancer Genome Consortium, the Cancer Genome Atlas project and NIH Roadmap Epigenomics Mapping Consortium to move the field forward.[4–6]

Compared to the rapid progress in technology development, the progress in treatment timing has been slow. Most clinicians rely on pathology reports that become available in due time, which often is too late to control or treat cancer. Molecular profiling and molecular classification of cancer are available in real time and may help to identify those cancer-associated biomarkers that are expressed much earlier than pathological symptoms and characteristics appear in histopathological analyses.[7,8] Once these biomarkers are included in personalized medicine, it will enable treatment to be implemented earlier, which will produce better outcomes. Although the traditional approach to personalized medicine has been 'reactive,' in the future it will be 'proactive.'

For cancer diagnostics, several targeted drugs are being developed and they have a companion diagnostic (CoDx) linked to their use. CoDx, which specifically targets a drug to an individual who is predicted to respond, has led to the identification and successful use of drugs such as vemurafenib, which targets BRAF mutations in metastatic melanoma, and crizotinib, which targets EML4–ALK mutation in non-small-cell lung cancer (NSCLC).[9] However, many commonly used therapeutic agents, especially costly ones, do not have validated CoDx tests and are ineffective in most cases.[10] Ideally, the CoDx test serves as a gatekeeper and the assay must live up to the same regulatory standards as for drug development itself.[11]