Identifying markers for optimal response
28 July 2017
Wouldn’t it be great if your doctor could know if you would respond to treatment before you even had it?
Researchers at Melanoma Institute Australia (MIA) have been looking at markers in the blood to determine if immunotherapy treatment is working early on in treatment before changes can be detected on x-rays or clinically.
“We don’t currently have great biomarkers to predict which patients will respond to immunotherapies,” comments Professor Richard Scolyer, Conjoint Medical Director and study co-author from MIA. “For targeted therapies, we have the presence of a certain BRAF gene to help identify if someone will respond to treatment. But we have nothing like this for immunotherapies or laboratory tests we can use to monitor response to treatment... until now.”
Researchers have found abnormal DNA that is released by the patient’s tumour and sent around the bloodstream, known as circulating tumour DNA or ctDNA, decreases in patients who are responding well to therapy. The levels do not decrease to the same degree in patients who aren’t responding to therapy.
Perhaps the best part about this for patients is that this can be determined as simply as via a blood test.
“With patients on targeted therapies, the day after they begin treatment, they often have incredible clinical benefit or a change in response that can be seen right away,” says Prof Scolyer. “However, when patients are given immunotherapies, we don’t know right away if the patient is responding as you’re trying to get the immune system to attack the tumour and this takes time. Patients sometimes get disheartened.”
Clinicians looking after the patient use radiology to check if the patient is responding to treatment but this is often not straightforward to interpret. Sometimes pseudoprogression can occur, where it looks like the patient’s tumour is growing. In fact the body’s immune system is attacking the tumour, making it look bigger on radiology. This can go on for a few months and the clinician may be tempted to change treatment because of this. This is where the simple blood test could come into play.
“Levels of ctDNA in patients responding to immunotherapy decreased well before radiological response was seen,” comments Dr Jenny Lee, a medical oncologist and researcher driving the ctDNA project at MIA. “A simple blood test can provide clinicians with a more accurate and earlier marker of how well a patient is responding, potentially guiding ongoing systemic therapy.”