The Role of Imaging Biomarkers

Imaging biomarkers have been developed for use in early cancer diagnosis, staging and restaging of disease and monitoring the effects of therapeutic interventions. In addition, biomarkers for evaluating coronary function and perfusion are well-established. Imaging biomarkers targeting neurodegenerative diseases also are widely used in the clinic.

18F-fluorodeoxyglucose will remain the most important imaging biomarker in neurology and oncology. However, with our increasing understanding and knowledge of biology, there is a need for refinement to better visualize such processes as tumor neo-angiogenesis, apoptosis, metastatic potential, receptor status and many more.

For neurological applications, imaging biomarkers that allow for a reliable detection of plaques and/or tangles would greatly assist in developing those drugs that might arrest neurodegenerative processes. However, all new imaging biomarkers need to undergo a rigorous validation process from cells through animal experiments to clinical trials. This pathway is time-consuming and expensive, and innovative approaches are needed to make this process more efficient.

There are several important reasons for accelerating the development of imaging biomarkers. First, personalized medicine will require markers that allow the prediction of which therapeutic is likely to be effective in which patient; second, in drug development, imaging biomarkers could be used to determine whether the therapeutic target is present and whether the target is “hit” by the drug. Finally, surrogate markers of treatment responses such as FDG can be used to assess therapeutic responses early and robustly which, in turn, can lead to appropriate changes in therapeutic approaches.

We will likely look back on this decade as the decade of the biomarker—a time in which medical researchers recognized opportunity, challenged technology and themselves, and developed and validated organ-specific biomarkers that will better predict patient outcomes.
Among the challenges are validation and standardization procedures and the establishment of true reference standards for imaging biomarker performance. These necessary housekeeping activities are very expensive given that dozens, if not hundreds, of biomarkers are being developed. Without a close interaction between government agencies and industry, the successful translation of imaging biomarkers into the clinic will not be possible.

Imaging biomarkers have their fair share of opportunity and challenge, but great successes have been achieved—in assisting in diagnosing, staging and monitoring sarcoma, metastatic breast cancer, lymphoma, head and neck cancer and gastric cancer as well as coronary artery disease, significant infection and identifying Alzheimer’s disease prior to the onset of problems as well as Huntington’s disease.

Johannes Czernin, MD

Professor, Molecular & Medical Pharmacology
Director, Nuclear Medicine Clinic, Positron Emission Tomography/Computed Tomography
David Geffen School of Medicine at UCLA, Los Angeles, Calif.

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