Laboratory Services

DNA Damage Response

DNA Damage Response Assays for Non-Invasive Treatment Response Monitoring

CelLBxHealth’s DDR assays provide a 360° view of the DNA damage response pathway, from early DNA damage signaling (γH2AX), through downstream repair activation (pKAP1), to the consequences of failed repair (micronuclei).

Disrupting the DDR pathway in tumor cells via DDR inhibitors has become an exciting new avenue for targeted treatment, either alone or in combination with established therapies¹,². Eligibility for DDR inhibitor treatment is currently assessed via expression of specific biomarkers in tumor tissue. However, the availability of tumor tissue can be limited, and tissue biopsy is invasive, highlighting the potential for liquid biopsy as an alternative means of assessing DDR biomarkers.

CelLBxHealth’s DDR assays enables researchers to monitor treatment response in real-time and supports the development and personalization of DDR-targeting therapies.

Sample Staining

γH2AX assay

Gamma H2AX (γH2AX) is a key component of the DDR pathway. It is formed as one of the earliest steps in the DDR cascade.  Assessment of γH2AX can inform DNA damage in a range of cell and tissue types, including CTCs³,⁴. Liquid biopsy CTC analysis provides a minimally invasive means to monitor γH2AX throughout treatment, providing real-time insights into the effectiveness of DNA-damaging therapies to potentially predict patient outcomes³.

Image showing immunofluorescence staining of DAPI (blue), γH2AX (orange) foci nuclear staining in a breast cancer cell line.

pKAP1 assay

pKAP1 is a key component of the DDR pathway and is responsible for activating downstream targets which are the focus of many current DDR inhibitors.

Unlike γH2AX, pKAP1 has not been studied as extensively as a potential biomarker of DDR. However, pKAP1 expression has been observed in several cancers and its value as a biomarker for diagnosis, prognosis and monitoring of disease in the clinical therapeutic environment is increasing.

Image showing immunofluorescence staining of DAPI (blue) and pKAP1 (orange) pan-nuclear staining in a breast cancer cell line.

Micronuclei assay

Micronuclei are membrane-bound compartments that contain DNA and are separated from the main nucleus within the cytoplasm¹⁰,¹¹. They form when chromosomes or chromosome fragments fail to segregate properly during cell division, often due to unresolved DNA damage¹⁰,¹¹. Their presence reflects chromosomal instability and indicates that DNA damage has exceeded the cell’s repair capacity, making them a strong marker of DDR failure, and treatment response to DDR-targeting therapies¹².

Image showing micronuclei identified using CelLBxHealth’s immunofluorescence assays. An example of a micronuclei is indicated by the orange arrow.

How could a DDR assay improve DDR drug discovery and help personalize cancer treatment?

CelLBxHealth’s DDR assays have the potential to:

  • Enable minimally invasive and repeatable liquid biopsy assessment of DDR markers on CTCs
  • Provide insight into the study of new DDR targets of interest
  • Provide an early competitive advantage in understanding therapeutic response to DDR inhibitors sooner
  • Reduce DDR inhibitor drug trial size, cost and time
  • Facilitate longitudinal monitoring of DDR markers and response to treatment

Research Findings

The markers and assays are built on a foundation of research:

An increase in γH2AX-positive CTCs was seen after a single dose and there were dynamic changes in γH2AX positivity over time with different chemotherapy regimens.¹
In a study of radium-223 therapy, an increase in γH2AX-positive CTCs was associated with a lower risk of death.²
In patients with breast cancer, γH2AX positivity increased after treatment with veliparib, doxorubicin and cyclophosphamide in tumor tissue although there was only sufficient tissue in 6 out of 10 patients.³ In contrast, CTCs were isolated from 27 patients and treatment increased γH2AX expression at day 7 and 14.
These studies highlight the potential utility of CTCs and DDR marker analysis for minimally invasive and rapid assessment of treatment response over time.

Discover how DDR assays can benefit your trial

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    Resources related to DNA damage response (DDR)

    Scientist holding blood sample

    Posters

    January 2025

    DDRi Summit 2025: Monitoring of DNA Damage Response Biomarkers using Circulating Tumour Cells captured with ANGLE’s Parsortix® instrument from Ovarian, Prostate, and Breast cancer patients

    ANGLE Europe Limited, Guildford, UK, published at the 8th Annual DDR Inhibitors Summit 2025

    Open PDF

    Posters

    September 2024

    DDR Conference – Detection of DNA Damage Response Biomarkers in Circulating Tumour Cells using ANGLE’s Parsortix® instrument and downstream immunofluorescence assays
    Open PDF

    Publications

    May, 2023

    Transcriptome Profiling of Circulating Tumor Cells to Predict Clinical Outcomes in Metastatic Castration-Resistant Prostate Cancer
    Open PDF

    For Research Use Only. Not For Use in Diagnostic Procedures.

     

    References

    1. Alhmoud J, et al. DNA Damage/Repair Management in Cancers. Cancers(Basel). 2020 Apr; 12(4): 1050.

    2. Choi, W. Therapeutic Targeting of DNA Damage Response in Cancer. Int. J. Mol. Sci. 23, 1701 (2022).

    3. Valente, D. Factors to Consider for the Correct Use of γH2AX in the Evaluation of DNA Double-Strand Breaks Damage Caused by Ionizing Radiation. Cancers 14, 6204 (2022).

    4. Palla, V.-V. gamma-H2AX: Can it be established as a classical cancer prognostic factor? Tumour Biol. 39, 1010428317695931 (2017).

    5. Wang LH, Pfister TD, Parchment RE, et al. Monitoring drug-induced gammaH2AX as a pharmacodynamic biomarker in individual circulating tumor cells. Clin Cancer Res. 2010;16(3):1073-84. doi: 10.1158/1078-0432.CCR-09-2799;

    6. Chatzkel J, Mocha J, Smith J, et al. Circulating tumor cells and γH2AX as biomarkers for responsiveness to radium-223 in advanced prostate cancer patients. Future Sci OA. 2019;6(1):FSO437. doi: 10.2144/fsoa-2019-0092;

    7. Tan AR, Chan N, Kiesel BF, et al. A phase I study of veliparib with cyclophosphamide and veliparib combined with doxorubicin and cyclophosphamide in advanced malignancies. Cancer Chemother Pharmacol. 2022;89(1):49-58. doi: 10.1007/s00280-021-04350-x

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