From left: Dr. Bekim Sadikovic, section head for the molecular genetics laboratories, and Dr. Mark Vincent, oncologist, in the lab where EGFR mutations are tested using the circulating tumour DNA in a patient’s blood.
A first of its kind laboratory test in Canada validated at London Health Sciences Centre (LHSC) and made possible by research at Lawson Health Research Institute provides patients with non-small cell lung cancer a non-invasive option to be tested for a gene mutation and receive life-extending second line therapy medication.
Non-small cell lung cancers account for nearly 85 per cent of all lung cancers, with 10 cent of those tumors experiencing a mutation in the epidermal growth factor receptor (EGFR) gene.
“EGFR is a gene we all have that maintains normal tissue in the lung,” explains Dr. Mark Vincent, oncologist, London Regional Cancer Program (LRCP). “In some lung cancer patients, the gene turns on inappropriately causing cells to multiply in the lung, grow into cancer cells and eventually spread throughout the body.”
Usually the gene mutation appears in late stage lung cancers and patients are terminal. “There are pharmaceuticals, or first line therapy options, that block the gene mutation with high rate of success; however, their efficacy only lasts a year,” adds Dr. Vincent. After approximately a year, the effects of the mutation return and cancer cells continue to multiply.
A novel second-line therapy drug is available to block EGFR mutation, but patients require a biopsy to prove that the mutation has occurred. For small cell lung cancer patients, an invasive biopsy is associated with risk, particularly if the tumour is in a difficult to each place, “some patients cannot or opt not to receive a biopsy due to risks associated,” says Dr. Vincent.
Dr. Bekim Sadikovic, section head for the molecular genetics laboratories, and his team at London Health Sciences Centre’s Pathology and Laboratory Medicine program have validated a blood test capable of detecting EGFR mutations from tumours, using the circulating tumour DNA in patient’s blood. For patients having progressed through first line therapy, this new test reduces the need for additional invasive testing while identifying if the second line therapy would be appropriate to treat this new mutation.
“Our test requires a blood draw and we will know the results of the test within 24 to 48 hours,” says Dr. Sadikovic. “If the test detects an EGFR mutation in blood sample, we can be certain that the patient has the mutation in tumour tissue, without having to perform a surgical procedure or biopsy. Alternatively, in case of negative result, there is still a possibility of mutation in tumour, but the tumours may not have shed enough DNA to appear in the blood test.” Should a test prove negative, patients still have the option of a biopsy.
Within the past year, circulating tumour blood testing was only available in the United States of America and patients were required to pay for the testing. “We are now ahead of the curve in offering this option to our patients,” exclaims Dr. Vincent. A positive test result allows patient the option of a new second-line therapy that reverses the mutation. “We are able to give these terminal patients an added year of life. Importantly, toxicity is reduced in the second-line therapy drug and patients are able to live the remainder of their life with fewer complications and at a higher quality.”
“This is our first clinical application of a blood test that can detect genetic mutations in cancer,” continues Dr. Sadikovic. “We are developing our in-house capabilities to broaden testing to other cancers including melanoma or colon cancer.”