The Benefits of Companion Diagnostics
Written by Dr Niamh O’Reilly


In recent years there has been a rise in the availability of precision medicines, many of which require use of companion diagnostic tests to determine which patients will respond to the therapy.1 Innovative precision medicines can potentially cure previously untreatable diseases, however, they are expensive and represent a challenge for payers deciding which therapies to fund. Companion diagnostics may help prove the cost effectiveness of therapies along with providing a number of other benefits.

Tackling healthcare costs

Increasing healthcare costs globally have led to an emphasis on demonstrating both the clinical and economic value of therapies, which requires forward planning from companies seeking reimbursement. Recent European analysis has shown that companion diagnostics represent a small segment of in vitro diagnostics spending and less then 1% of total healthcare expenditure.2 Yet these specialised diagnostic tests represent a way to minimise inefficient use of healthcare resources by identifying sub-populations of patients that are most likely to achieve positive outcomes from a therapy.2

Increasing need for personalised therapies

Oncology is a therapeutic area where treatments have become increasingly personalised therefore creating a growing need for companion diagnostics.3 Traditionally, treatment options (including surgery, radiotherapy and chemotherapy) may have been limited resulting in most patients receiving the same or similar treatment based on the type and stage of their cancer.4 This approach achieved varying degrees of success among patients with some being cured of their disease, while others were exposed to harsh side effects with little or no improvement to their health.

In recent years, advancements in cancer biology research have revealed high levels of variation in the genetic mutations that lead to the development of cancer, which could account for the variation in patient response to a therapy. Recently, many drugs, particularly those to treat cancer, have been developed to target specific aspects of the disease. For example, a drug therapy (such as a monoclonal antibody) may bind to a specific biomarker on cancer cells or turn on an aspect of the patient’s immune response. By developing companion diagnostics to identify these specific biomarkers in a patient’s blood or tissue biopsy, the patients most likely to respond to the targeted therapy can be identified.

Benefits of improved data collection

Companion diagnostics can add value throughout all stages of clinical development of a therapy by providing a mechanism to collect useful data. During the pre-clinical stage, a diagnostic test could be used to assess the likely success of a proposed therapy, thus reducing the chance of incurring substantial costs at the later stages of development.5 As a potential therapy advances through the clinical trial stages, use of a companion diagnostic could facilitate selection of those patients most likely to respond favourably to the drug. By identifying a well-defined patient population, companies could enrol fewer patients and potentially complete clinical studies in a shorter timeframe which could result in reduced costs.3,6

Inclusion of a companion diagnostic has been attributed with taking a therapy from second or third line treatment in the general population to a first line therapy in a sub-population which can lead to increased revenues.3 Personalised medicines may also result in less adverse reactions which may contribute to healthcare savings.4 This precision approach allows companies to collect impactful data that may provide a more attractive package to payers by treating a select patient segment with greater potential to achieve the desired health outcomes.

CRC’s team has a wealth of experience to assist our clients in their Medical Affairs needs throughout the drug development lifecycle. 


  1. Brooks E. A. & Bergstrom F. Companion Diagnostics: Important Health Economics and Reimbursement Considerations. Decision Driver Analytics. Available at: http://www.decision-driver.com/companion-diagnostics-white-paper.aspx
  2. Wurcel V. et al. The value of Companion Diagnostics: Overcoming Access Barriers to Transform Personalised Health Care into an Affordable Reality in Europe. Public Health Genomics Journal.
  3. Agarwal A. et al. The current and future state of companion diagnostics. Pharmacogenomics and Personalised Medicine Journal. Available at: https://www.ncbi.nlm.nih.gov/pubmed/25897259
  4. ADC Review. Companion Diagnostics: Paving the way for personalised medicine. Available at: https://adcreview.com/news/companion-diagnostics-and-personalized-medicine/
  5. Leamon C. 2013. Companion Diagnostics: Improving development success and patient care. Available at: https://www.genengnews.com/gen-articles/companion-diagnostics-improving-development-success-and-patient-care/4957
  6. Danner S. et al. Capitalizing on precision medicine: How pharmaceutical firms can shape the future of healthcare. Available at: https://www.strategyand.pwc.com/reports/capitalizing-precision-medicine