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RadTox offers
Personalized Treatment Effectiveness 

By comparing conditions before treatment, after treatment, and even during long-term surveillance in the recovery phase

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The RadTox™ test monitors tumor treatment responses in patients of different cancer types by measuring the total cell-free DNA (cfDNA) from plasma.

Longitudinal Serial Real-Time Monitoring Tool

Because of the short turnaround time and low cost, the RadTox™ test can serve as a longitudinal serial monitoring tool for tumor responses multiple times during and after treatment, including the transition from disease progression to stable disease, and to recurrence.

Comprehensive Tumor Response Monitoring Tool

Combined with circulating tumor DNA (ctDNA) vertical monitoring deep into clonal evolution and treatment resistance at a treatment point, the cancer management by liquid biopsy becomes more comprehensive and valuable as a complementary tool to imaging.
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Although there is no easy way to separate ctDNA from the rest of the cfDNA, specific ctDNA (not the total ctDNA) biomarkers can be identified and quantified by the presence of cancer mutations. The total cfDNA, on the other hand, can be quantified once the plasma is isolated from the rest of the blood.

Liquid biopsy: cfDNA vs. ctDNA

In recent years, liquid biopsy has gained traction for different clinical applications, including early detection, prognosis, and treatment monitoring. cfDNA and ctDNA are the two most essential biomarkers commonly studied and gradually adapted in clinical settings.

Cell-free DNA (cfDNA)

cfDNA is the total DNA released into the bloodstream, consisting of DNA fragments from normal cells and tumor cells.

Circulating Tumor DNA (ctDNA)

Refers to DNA fragments from only tumor cells. At the early stage of cancer development, ctDNA is only a small fraction of cfDNA, as low as 0.01 to 1%. However, with faster tumor cell growth and turnover compared to normal cells, the proportion of ctDNA has significantly increased at the late stage of advanced cancer, reaching even 90% of the total cfDNA.
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Cell-Free DNA (cfDNA)

Total cfDNA quantification as a biomarker for prognosis and treatment response

Although total cfDNA varies between individuals, total cfDNA quantification has been found to be a promising biomarker for cancer prognosis and treatment responses in many publications.

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Here are some of the findings about the total cfDNA level:

  • Healthy individuals vs. cancer patients: Cancer patients have much higher cfDNA, even 200-fold more

  • Early stages vs. late stages: Late-stage cancer patients have much higher levels of cfDNA than early-stage patients

  • Cancer cell number: Patients with bigger tumor mass has more cfDNA

  • Prognosis: Patients with more cfDNA has a shorter progression-free survival (PFS) or overall survival (OS)

  • Treatment responses: cfDNA decreases in progression-free patients and increase in patients with recurrence and metastasis

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Due to the lack of specificity of cfDNA quantification in cancer types and limited ctDNA in early-stage cancer, cfDNA quantification is a more favorable predictive and prognostic biomarker in cancer treatment response monitoring than a diagnostic biomarker.

ctDNA Monitoring or Total cfDNA
Quantification Monitoring?

Like total cfDNA quantification, ctDNA quantification has shown great value in prognosis and treatment response monitoring, specific for the individual patient with prior knowledge of the mutation information. In addition, the genomic profiling of the ctDNA provides guidance for target therapy and monitors tumor recurrence or therapy resistance through residual diseases with the known clone evolution mutants, which can’t be done with cfDNA quantification. However, total cfDNA quantification can be used for monitoring treatment responses and cancer recurrence through the total cfDNA level changes over time.
  • What is the RadTox™ test and how does it work?
    RadTox™ is a liquid biopsy test that quantifies circulating cell-free DNA (cfDNA) levels in plasma to monitor cancer treatment response and prognosis, using proprietary isobDNA™ technology.
  • What are the main advantages of the RadTox™ test over other liquid biopsy tests of the same indications?
    Key advantages include pan-cancer applicability, earlier detection of treatment response than imaging, small sample requirement, cost-effectiveness, and rapid turnaround time.
  • How does the RadTox™ test complement imaging and other diagnostic tests?
    RadTox™ provides real-time insights into tumor dynamics and treatment response, often earlier than imaging, and complements imaging and tissue biopsies for comprehensive monitoring.
  • Is RadTox™ ready for clinical use and covered by insurance?
    Yes, RadTox™ is a CLIA-certified LDT, and is covered by Medicare and some private insurers starting January 2024.
  • For which cancer types is the RadTox™ test suitable?
    RadTox™ test is a pan-cancer test suitable for monitoring treatment responses and tumor recurrence across all solid tumor types and stages, without the need for prior tumor genomic profiling.
  • How frequently can the RadTox™ test be performed?
    RadTox™ can be performed as frequently as weekly or biweekly during active treatment, and monthly during surveillance, enabling continuous monitoring.
  • What is the turnaround time for RadTox™ test results?
    The RadTox™ test has a rapid turnaround time of approximately 5-7 days, facilitating timely clinical decision-making.
  • How does the RadTox test compare to ctDNA (circulating tumor DNA) tests?
    While ctDNA tests provide genomic insights, RadTox™ quantifies total cfDNA levels, offering a complementary perspective on tumor burden and treatment response.
  • Can the RadTox™ test predict treatment outcomes or prognosis?
    Yes, studies show that baseline cfDNA levels and changes during treatment can be prognostic for outcomes like overall survival and progression-free survival.
  • How sensitive is the RadTox™ test in detecting molecular residual disease or tumor recurrence?
    RadTox™ can detect significant increases in cfDNA levels that may indicate molecular residual disease (MRD) or tumor recurrence, often earlier than imaging or conventional biomarkers.
When target therapy is involved, ctDNA monitoring is the choice for monitoring therapy efficacy, therapy resistance, and minimal residual disease.

We recommend using both cfDNA quantification as well as ctDNA monitoring tools to monitor treatment responses as they complement each other and provide different values.

If frequent, overall monitoring without looking into individual tumor clones is desired, cfDNA quantification monitoring can be chosen for faster and real-time monitoring.
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The RadTox™ test measures total cfDNA without extracting cfDNA, providing the benefits of accuracy and small plasma sample size (as little as 10 μL plasma used in the test). These benefits allow serial monitoring to become practical in a clinical setting.

Questions? Email radtox@diacarta.com
(1) Pantel et al. Liquid biopsy and minimal residual disease—Latest advances and implications for cure. Nat. Rev. Clin. Oncol. 2019, 16, 409–424.
(2) Diehl et al. Circulating mutant DNA to assess tumor dynamics. Nat Med 2008, 14:985-990.
(3) Diaz Jr, LA and A. Bardelli. Liquid Biopsies: Genotyping Circulating Tumor DNA. J Clin Oncol 2014, 32:579-586.
(4) Schwarzenbach et al. Detection and Monitoring of Cell-Free DNA in Blood of Patients with Colorectal Cancer. Ann. N.Y. Acad. Sci. 2008, 1137: 190–196.
(5) Park et al. Quantitative analysis of cell-free DNA in the plasma of gastric cancer patients. ONCOLOGY LETTERS 2012, 3: 921-926.
(6) Gautschi et al. Circulating deoxyribonucleic Acid as prognostic marker in non-small-cell lung cancer patients undergoing chemotherapy. J Clin Oncol. 2004 Oct 15;22(20):4157-64.
(7) Fernandez-Garcia et al. Plasma cell-free DNA (cfDNA) as a predictive and prognostic marker in patients with metastatic breast cancer. Breast Cancer Research 2019, volume 21, Article number: 149
(8) Dao et al. Using cfDNA and ctDNA as Oncologic Markers: A Path to Clinical Validation. Int J Mol Sci. 2023, Sep; 24(17): 13219.
(9) Frattini et al. Quantitative Analysis of Plasma DNA in Colorectal Cancer Patients A Novel Prognostic Tool. Ann. N.Y. Acad. Sci. 2006, 1075: 185–190.
(10) Hu et al. Post surgery circulating free tumor DNA is a predictive biomarker for relapse of lung cancer. Cancer Med. 2017 May;6(5):962-974.
(11) Carrasco et al. 2022. Cell-Free DNA as a Prognostic Biomarker for Monitoring Muscle-Invasive Bladder Cancer. Int. J. Mol. Sci. 23, 11732.
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