Establishment of an assay for circulating DNA to detect T790M mutation in patients with lung cancer
Challenge

Patients with non-small cell lung carcinomas which harbour activating mutations in EGFR are treated with tyrosine kinase inhibitors (TKs) as targeted agents - but inevitably tumours become resistant.

One of the most common mechanisms for this resistance is the development of the secondary mutation T790M in the EGFR gene. Assessment of the mutation status of the tumour is key to ensuring the right treatment for the right patient.

How did the facility help?

The TIA Facility at Peter Mac developed an assay to detect the EGFR T790M resistance mutation in plasma using a digital droplet PCR technique. They developed the assay rapidly and were able to offer it in a NATA accredited environment such that patients did not require an invasive tumour biopsy. This means we can offer a blood test for patients and those that were positive for this mutation were able to access a much more effective drug, increasing quality of life.

Outcome

The facility provided an excellent service for my patients. The use of a simple blood test has enabled my patients to access osimertinib rapidly and far earlier and with more ease than if biopsies were used. An example is for a 60-year- old retired teacher with a prior history of breast cancer who 10 years later have multiple lung lesions identified on imaging. A lung lesion was resected and subsequent testing revealed an EGFR mutation. She was commenced on treatment with the EGFR TKI erlotinib (Tarceva) but despite an excellent initial response later developed progression of disease in bones and in a lung metastasis. A biopsy was planned to obtain tissue for molecular testing - however we were able to arrange plasma testing for circulating tumour DNA through which a T790M mutation was identified. This allowed us to cancel the biopsy and to commence treatment with Osimertinib. She has had recent scans confirming response to therapy.

 

  • Prof Ben Solomon, Medical Oncologist, Peter MacCallum Cancer Centre

Background

The TIA facility is embedded within the Diagnostic Pathology Laboratory of the Peter MacCallum Cancer Centre, Australia’s only dedicated cancer hospital. The Department focuses on cancer patients performing quaternary level pathology testing over a range of disciplines including the largest cancer specific NATA‐ accredited molecular pathology laboratory. Thus the TIA-funded facility at Peter Mac is fully integrated into the diagnostic lab and is supported by 8 pathologists and 35 molecular pathology scientists. The facility is able to offer state‐of‐the‐art protein, RNA and DNA molecular pathology services providing high throughput routine diagnostic molecular services on multiple test platforms including massive parallel sequencing, to supporting patient care, basic and clinical research with particular emphasis on ancillary biomarker studies in small and large‐scale clinical trials.

PeterMac Diagnostic Pathology Laboratory

Level 14, 330 Collins St

Melbourne 3000 VIC

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T: +61 (07) 3735 4433

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