Measuring gamma-H2AX as a biomarker for DNA damage after ionizing radiation treatment in cancer patients

Pegah Johansson1,*, Aida Muslimovic1, Ragnar Hultborn2, Erik Fernström2, Ola Hammarsten1

1Clinical Chemistry, 2Oncology, Sahlgrenska University Hospital, Göteborg, Sweden

Introduction: For the majority of cancer patients, ionizing radiation therapy and /or chemotherapeutics that induce DNA-double strand breaks (DSB) are the mode of treatment, resulting in the cancer cell death. There is an inherent variation in population sensitivity to these treatments and the doses prescribed today are largely based on the clinically determined tolerance of the normal tissues to the treatment, and have evolved to limit the proportion of patients who will suffer severe adverse reactions to about 1-5% of cases. Thus, many patients receive sub-optimal doses while the sensitive minority is relatively overdosed causing many severe side effects and occasionally death.  

Objectives: We aim to develop a clinical assay to identify sensitive individuals prior to commencing treatment, as well as to monitor the patient’s response during the course of treatment leading to biologically-guided personalized treatment in oncology.

Methods: The measurement of DNA double-strand breaks has been proposed as a useful biomarker in evaluating tissue damage in response to DNA treatment.  Induction of DSB is followed by the rapid phosphorylation of H2AX molecules flanking the break site referred to as gamma-H2AX. Gamma-H2AX forms foci that can be labelled, detected, and quantified using immuno-fluorescence imaging or flow cytometry. Neither of these techniques has been successfully adapted for clinical applications. We have adapted both of these methods for use in the clinic.

Results: Here we present a pilot comparative study of gamma-H2AX measurements in patients undergoing radiation therapy using immuno-fluorescence imaging or flow cytometry  detection of gamma-H2AX in parallel.

Conclusion: Both methods were adapted and evaluated for clinical use and the advantages and limitations of each are discussed.

Keywords: Biomarker development, Blood, Cancer