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Commentary on Science, Innovation & New Products with a focus on Oncology, Hematology & Cancer Immunotherapy

Posts tagged ‘Imaging Biomarkers’

What is a Biomarker?

According to the Biomarkers Definitions Working Group, a biomarker is:

“a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.”

An example of a common biomarker is blood pressure. High blood pressure is a surrogate for cardiovascular disease and risk of stroke.

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Why are Biomarkers important?

Biomarkers can be used for diagnosis and for monitoring the safety and effectiveness of treatments. They are increasingly becoming important in the selection of patients for clinical trials, and as potential surrogates for clinical endpoints that may take a long time to occur e.g. measuring how long someone will live in a cancer trial (overall survival).

Examples of the use of biomarkers include:

  • Diagnosis: high blood pressure is used as a biomarker for cardiovascular disease and risk of stroke.
  • Treatment Selection: CSF biomarkers that correlate with neurodegenerative diseases may help select the most appropriate treatment
  • Drug Effectiveness: biomarkers can be used to monitor treatment or drug effectiveness e.g. use of cholesterol levels as a measure of cardiovascular disease
  • Surrogate Clinical Endpoint: a biomarker based on scientific evidence that predicts or correlates with clinical benefit could be used as a surrogate for a clinical endpoint that may take a while to detect e.g. how long a patient lives or survives, and in the process speed up drug development. Recent prostate cancer trials sought to show that circulating tumor cell (CTC) counts correlated with the survival benefits seen. However, validation of a biomarker needs to take place before regulatory agencies will accept it as a surrogate endpoint in clinical trials.

Biomarkers can be divided into those which are prognostic and those that are predictive.

Prognostic Biomarker: a marker that provides information on the likely course of a disease in an untreated individual.

Prognostic biomarkers are used to identify high-risk cancer patients who should, therefore, receive adjuvant therapy.

Predictive Biomarker: a marker that provides information on how likely you are to respond to a particular therapy.

Predictive biomarkers are used to guide treatment choices i.e. selecting the therapy with the highest likelihood of success.

In breast cancer, estrogen and progesterone receptors are biomarkers that predict sensitivity to endocrine therapy, while HER2 levels predict response to Herceptin treatment. In colorectal cancer (CRC) patients, KRAS mutations have been shown to be a biomarker of resistance to EGFR targeting drugs such as cetuximab and panitumumab.

Predictive biomarkers allow expensive new cancer treatments to be given only to those patients who are likely to respond. As we move forward into the era of personalized medicine the aim is to develop more highly predictive biomarkers that will allow better detection, diagnosis and treatment of disease.

In addition, there’s also a need to develop biomarkers that can distinguish between subgroups of patients to separate those who might benefit from a therapy and those who have developed resistance. Biomarkers for resistance to cancer therapy is an increasingly important area of research.

For those readers interested in cancer biomarkers, the joint ASCO-EORTC-NCI “Markers in Cancer” 2012 meeting in Hollywood, FL (near Fort Lauderdale) from October 11-13 has an agenda that holds promise.

Some of the presentations that caught my attention and ones I particularly look forward to watching remotely via the “Virtual Meeting” include:

  • Biomarkers of Resistance to EGFR-Targeted Therapies in Lung Cancer
    Enriqueta Felip, MD, PhD – Vall d’Hebron University Hospital
  • Resistance Mechanisms to BRAF Inhibition in Melanoma
    Jeffrey Sosman, MD – Vanderbilt-Ingram Cancer Center
  • Complexities of Identifying Non-Mutational Biomarkers of Resistance:
    The VEGF Pathway Example
    Michael B. Atkins, MD – Georgetown University
  • Development of Biomarkers for PI3K Pathway Targeting
    Sherene Loi, MD, PhD – Jules Bordet Institute, Brussels
  • Emerging Functional Imaging Biomarkers
    Annick D. Van Den Abbeele, MD – Dana-Farber Cancer Institute

The next post in this mini-series will discuss new research that shows how a panel of 5 CSF biomarkers can be used to differentiate between neurodegenerative diseases that might otherwise be misdiagnosed. This is particularly important for clinical trial recruitment where early symptomatic patients could potentially be recruited in error if given the wrong diagnosis, and placed in trials that they will not respond to.

One of the challenges of the next decade in cancer research will be targeting cancer metabolism; imaging is likely to play a key role in drug development.

NMR-image-of-brain-gliomaThe cover of the January 11 online issue of Science Translational Medicine (STM) shows a brain tumor (glioma) in red, detected using non-invasive nuclear magnetic resonance imaging that highlights cancer metabolism.

In a paper published in STM, Andronesi and colleagues from Harvard & other Cambridge, MA institutions (including Agios Pharmaceuticals – more on them later), showed that excess production of the metabolite 2-hydroxyglutarate (2HG) could be used as a biomarker for a subset of glioma.

The subset this metabolic biomarker identified, were those patients with mutations of the isocitrate dehyrogenase gene (IDH1), present in 86% of the grade II & III gliomas and secondary glioblastomas.

Agios Pharmaceuticals founded by eminent cancer researchers, Lewis Cantley, Tak Mak and Craig Thompson is targeting the IDH1 and IDH2 metabolic pathways.

They have shown that mutations of the metabolic gene IDH1 are consistent with that of a cancer-causing oncogene.  Interestingly, Agios notes on their website that IDH1 and IDH2 mutations have also been seen in acute myeloid leukemia (AML).

What makes 2HG a functional biomarker for glioma is its correlation with survival.  2HG accumulates in the brains of patients with IDH1 mutations. These patients have a greater survival than those with wild-type IDH1 gliomas.

Developing a drug that targets cancer metabolism in the brain is not easy. NMR imaging of the 2HG in the brain will help researchers non-invasively follow the effects of inhibitors of mutated IDH1. This is particularly important given that, according to Andronesi et al,  “no report exists about increased D-2HG in the blood, cerebrospinal fluid, or urine of glioma patients with IDH1 mutations.”

The January 11 online issue of STM, also contains another paper on the detection of 2HG using NMR. Elkhaled and colleagues from UCSF report a technique of proton high-resolution magic angle spinning spectroscopy.  Their data confirms the potential of 2HG as a surrogate marker of patient survival.

Cancer metabolism as a drug development target is an area I expect we will see more of in the next ten years.  Key to success will be the ability to identify biomarkers with which to assess and monitor the success of drug candidates.

The identification of 2HG as a biomarker for IDH1 in glioma patients shows that cancer metabolism is an area of potential for drug development.

One cloud on the horizon for Agios Pharmaceuticals is, however, the filing of a lawsuit late last year by the Abramson Cancer Institute of the University of Pennsylvania. This alleges that Craig Thompson concealed the start-up of Agios while working for Penn, and in essence took the intellectual property of the University to the company. The merits of this claim have yet to be decided.


ResearchBlogging.orgAndronesi, O., Kim, G., Gerstner, E., Batchelor, T., Tzika, A., Fantin, V., Vander Heiden, M., & Sorensen, A. (2012). Detection of 2-Hydroxyglutarate in IDH-Mutated Glioma Patients by In Vivo Spectral-Editing and 2D Correlation Magnetic Resonance Spectroscopy Science Translational Medicine, 4 (116), 116-116 DOI: 10.1126/scitranslmed.3002693

Elkhaled, A., Jalbert, L., Phillips, J., Yoshihara, H., Parvataneni, R., Srinivasan, R., Bourne, G., Berger, M., Chang, S., Cha, S., & Nelson, S. (2012). Magnetic Resonance of 2-Hydroxyglutarate in IDH1-Mutated Low-Grade Gliomas Science Translational Medicine, 4 (116), 116-116 DOI: 10.1126/scitranslmed.3002796

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A company I have been watching for a while is Philadelphia based Avid Radiopharmaceuticals, now a wholly owned subsidiary of Lilly. They have a novel imaging biomarker, florebetapir (18F-AV-45) in development for the detection of Alzheimer’s disease.

In a press release last week, Lilly announced that the FDA had assigned a priority review to the marketing application of florebetapir. The Peripheral and Central Nervous System Drugs Advisory Committee of the FDA meet on January 20, 2011.

Bayer have a competitor product in development, forebetapen (BAY 94-9172). Both florebetapir and florebetapen are 18F radiolabelled imaging biomarkers that bind to amyloid plaque in the brain.  When used in conjunction with a Positron Emission Tomography (PET) scan, they enable the accumulation of amyloid that occurs in Alzhemeir’s disease to be visualized.

Phase 3 trial results for florebetapir published earlier this year showed that the brain amyloid burden seen in the PET scans positively correlated with the plaques seen in autoposies of the same patients.  Proof that what the imaging biomarker shows is an accurate representation of the underlying pathology.

What makes the use of florebetapen and florebetapir interesting is that it is already common practice to use imaging tracers with PET scans. Fluorodeoxyyglucose (FDG) is widely used in the diagnosis, staging and treatment of oncology patients as a result of its ability to show the intense glucose uptake that occurs with most cancers.

Both Avid and Bayer products are most likely to be approved based on the clinical data presented to date.  It will be interesting to see the prices that they intend to charge.

As for the market opportunity, they are likely to have a role to play in the early diagnosis of patients with mild cognitive impairment, since at present it is difficult to diagnose these patients and differentiate Alzheimer’s disease from other forms of dementia.  Most likely, models will be developed that look for a correlation between accumulation of amyloid plaque and decline in cognitive function, from which a probability of developing Alzheimer’s disease can be calculated.

Imaging biomarkers are likely to place an increasingly important role in the development of new products by biotechnology companies and in the design of clinical trial endpoints.

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