Frequently asked questions

  • Could ToxNav help me?

    ToxNav is used to help patients who are have been diagnosed with Colorectal cancer and are about to undergo treatment with a 5FU/Capecitabine based
    chemotherapy regime.

  • Can you show me validation of the use of ToxNav in the clinical setting?

    The ToxNav panel was clinically validated in 888 patients from the QUASAR2 clinical trial.

  • How long does ToxNav screening take?

    It should be no more than two weeks from the time that the sample is sent off to when the ToxNav report is received by the referring clinician.

  • How can I order a ToxNav test?

    If you are interested in purchasing ToxNav please get in touch with us via telephone on +44 (0)1865 784742

  • Why is ToxNav different to other genetic tests for 5FU toxicity?

    The genetic basis of 5FU toxicity is complex and includes many genetic variants and environmental factors, each of which may constitute a small or large aspect of anindividual’s susceptibility. Oxford Cancer Biomarkers has carefully included in the test the 20 genetic variants that show the predictive value. By doing so we maximise thechances of finding the individuals who are at risk of toxicity.

    In addition to this, ToxNav tests for certain variants known to be associated with Hand and Foot syndrome (HFS) also known as palmar-plantar erythrodysesthesia. HFS is a painful, chemotherapy-induced reddening, swelling and peeling of the hands and feet that can have a significant impact on a patient’s quality of life. A test that identifies those patients susceptible to HFS would allow them to be pre-emptively treated since treatment is simple and non-invasive. This may allow them to continue with chemotherapy for longer.

  • Which sequencing method do you use?

    DNA from your patient’s sample is sequenced at our partner lab using PCR of the relevant genetic sequences, followed by Sanger sequencing.

  • What type of sample is needed from the patient?

    A 4ml venous blood sample is required and should be collected in a vacutainer and packaged within the sample tube provided by OCB.

  • Where should we send the blood sample once we have collected it from the patient?

    The sample should be sent to our partner lab for sequencing. Instructions for where to send the sample will be included with the sample kit.

  • Can patients buy ToxNav kits directly from OCB?

    We work in partnership with medical professionals including oncologists and pathologists to ensure the safe use of our tests and accurate interpretation of results. For this reason, we do not trade directly with patients.

  • Do the samples need to be cooled or frozen prior to sending them off?

    Samples can be sent at room temperature via Royal Mail in the envelope provided.

  • Why does ToxNav test for 20 genetic variants?

    The genetic basis of 5FU toxicity is complex and includes many genetic variants and other factors, each of which may constitute a small or large aspect of an individual’s susceptibility. Oxford Cancer Biomarkers has carefully included in the test the 20 genetic variants that show the predictive value. We also include variants associated with HFS so, unlike other 5FU toxicity screens, ToxNav specifically stratifies patients based on their risk of HFS as well as other elements of toxicity. This creates an extra stratum of patients that can have HFS pre-emptively managed without the need to alter the rest of their treatment.

  • How long do you store patients’ sequencing data for?

    Raw and processed sequence data is retained indefinitely in order to comply with traceability and the IVD regulations.

  • How sensitive and specific is ToxNav?

    When predicting a level of risk of toxicity induced death, ToxNav has a sensitivity of 100% and a specificity of 98%.

    When predicting a level of risk of grade 4 haematological toxicities, ToxNav is has a sensitivity of 75% and a specificity of 98%.

    When predicting a level of risk of hand and foot syndrome, ToxNav has a sensitivity of 83% and a specificity of 31%.

  • How long do you keep patients’ samples?

    Patients’ samples are retained for 3 months.

  • What is the positive predictive value of ToxNav?

    When predicting a level of risk of toxicity induced death, ToxNav has a positive predictive value of 0.1.

    When predicting a level of risk of grade 4 haematological toxicities, ToxNav has a positive predictive value of 0.14.

    When predicting a level of risk of hand and foot syndrome, ToxNav has a positive predictive value of 0.25.

  • What if my patient’s sample is lost?

    If it is more than two weeks since your patient’s sample was sent off and you have not heard from us then please contact us on +44 (0)1865 784742
    so that we can resolve this for you.

  • What is the negative predictive value of ToxNav?

    When predicting a level of risk of toxicity induced death, ToxNav has a negative predictive value of 1.0.

    When predicting a level of risk of grade 4 haematological toxicities, ToxNav has a negative predictive value of 1.0.

    When predicting a level of risk of hand and foot syndrome, ToxNav has a negative predictive value of 0.87.

  • Is ToxNav appropriate for testing patients who have other types of cancer?

    ToxNav has only been validated for use on patients with colorectal cancer. As 5FU toxicity is not limited by cancer type, ToxNav could potentially be useful in other cancers. OCB is currently validating ToxNav in other solid tumours.

  • What data is the ToxNav test based on?

    ToxNav is based on identification of relevant single nucleotide polymorphisms (SNPs) associated with 5FU/Capecitabine toxicity in a number of genome wide association studies and meta analyses. This selection of SNPs was then further developed to incorporate the final 20 SNPs.

  • Is it safe to reduce my patient’s dose of chemotherapy in line with the recommendations of the ToxNav report?

    The recommendations of dose modulation made in the ToxNav report are recommendations only. They are designed in line with the guidelines of the Clinical Pharmacogenetics Implementation Consortium. ToxNav results should always be interpreted along with other patient specific factors and comorbidities including sex and age in order to ensure the best possible outcome for each patient.