Delivering precision pain relief at the right time

As a palliative care physician and medical oncologist, Dr Aaron Wong spends most of his working day supporting patients with advanced and incurable cancers. Many of those patients live with moderate to severe pain because of their cancer, and they rely on opioids to try and manage pain levels.

However, for around one in five patients, the opioids they are prescribed do not work – a situation described as ‘opioid failure’.

Dr Aarong Wong.

Either the drugs don’t alleviate the patient’s pain, or they cause a range of intolerable side effects including drowsiness, nausea, vomiting, itching, hallucinations, confusion and constipation. So patients will be prescribed a different type of opioid and then another if that doesn’t work.

Dr Wong is currently completing a PhD through the University of Melbourne’s Department of Medicine that is investigating pharmacogenomics as a predictive biomarker to guide opioid prescribing in cancer patients. His work was recognised in the 2023 Picchi Awards from the Victorian Comprehensive Cancer Centre (VCCC).

“My hope for my research is that patients can be prescribed an opioid that suits them upfront, to prevent opioid failure and the need for opioid switching which increases hospital admissions, suffering and mortality at what is probably already the most stressful time of their lives,” says Dr Wong. He completed a Bachelor of Medicine and Bachelor of Surgery at the University of Melbourne and currently is Palliative Care Clinical Trials Lead at the Peter MacCallum Cancer Centre and the Royal Melbourne Hospital.

“Essentially, this research is about performing a blood test or cheek swab when patients first present and then using that information to prescribe the right opioid to the right person at the right time.”

Currently, nine opioid medications are available for prescription in Australia although morphine and oxycodone are most commonly prescribed in cancer care. Dr Wong says this research works towards pinpointing a patient’s specific gene profile on a blood test or cheek swab to determine which opioid a patient will respond to most effectively.

“So, when a patient diagnosed with advanced cancer walks through the door, we would do a simple blood test that will tell us whether we should use opioid A, B, C or D. The gene profile would also indicate which opioids would create side effects for that patient, or require them to take smaller or larger doses than expected to control their pain,” explains Dr Wong.

“Opioid choice would be based on objective data from genetic blood tests and biomarkers.”

In oncology care, some patients already have a blood test to determine if they will be able to process chemotherapy treatment effectively. Dr Wong says the proposed opioid blood test could be a useful addition to early treatment soon after patients are diagnosed with cancer.

As soon as pain reaches a stage where the patient requires opioids, treating practitioners could refer to their gene profile blood test results to determine which opioid to prescribe.

Dr Wong has also undertaken research involving 200 patients that mapped their opioid journey and when they were prescribed medication in relation to diagnosis. He found most patients with advanced cancer needed opioids to manage pain within about 10 days of their first hospital encounter.

He has also looked at 35 neuroimmune genes and found signals in 10 genes that impact pain level, the likelihood of patients needing higher or lower doses of opioids, and their likelihood of experiencing side effects from the medication.

The next stage of Dr Wong’s research will involve more patients having blood tests to identify their polygenic risk score.

“It would be interesting to explore whether combinations of different candidate genes would provide stronger signals than what we are seeing now,” he says.

Dr Wong’s research is driven by his determination to help oncology patients live more comfortably with the right drug prescribed for the right person upfront.

“I want to be someone able to make a difference in their lives, a tangible difference that is helpful to those people,” he says.

“Patients who have supported this research are very giving. Many of our research participants know they won’t live to see the results of the research but they want to help the people who will come after them. They are the true inspiration behind this work.”