Dr Joseph Tucci’s career can be described as a classic case of two paths converging. After completing a PhD in developmental genetics at the Howard Florey Institute of Experimental Physiology and Medicine, Dr Tucci worked as a postdoctoral fellow at the University of Leicester in the UK before returning to Australia to embark on a career change – as a pharmacist.
“There are not many pharmacists with a PhD,” he said, “and it wasn’t long before I was teaching pharmacy practice at La Trobe.” Today, he’s an associate professor, combining his research expertise with his pharmacy training to address the HIV/AIDS crisis in Papua New Guinea (PNG).
Pharmacology meets genetics
Combine pharmacology with genetics and you end up with pharmacogenetics: research that examines how genes affect the body’s response to medications. We all process drugs differently, and our unique genetic blueprint can determine if a medication works, or not.
“There are some cancer drugs, for example, which will only be given to patients who possess particular genetic markers,” explains Dr Tucci.
“In breast cancer, about 30% of women carry a gene that activates a receptor that causes rapid tumour growth. There is a drug which targets that particular receptor and blocks it. Patients with this gene can take this medication, knowing that it is tailor-made for them and likely to have a successful therapeutic outcome. That is essentially how pharmacogenetics works.”
In these cases, genetic screening determines who will benefit from the treatment. “The United States and Europe have legislated in this area,” said Dr Tucci, “and some medications cannot be prescribed without a genetic test.” While this individualised approach to healthcare may be the way of the future, for most therapies it’s not so clear cut.
“If we take blood pressure medication, for example, there may be variations in the way that you or I process the drug. Some people may have more side effects than others. Some may not get any beneficial effects at all.”
Dr Tucci is passionate about the role that pharmacogenetics can play in addressing indigenous health problems in Australia and Papua New Guinea. “We have huge databases of genetic information on people of European descent, but there are large parts of the world where this data has never been collected,” he said. “The least studied groups are indigenous populations in Australia and PNG.”
Dr Tucci is particularly interested in the pharmacogenetic implications of life threatening diseases: together with Dr Paul Pumuye (a physician at the School of Medicine and Health Sciences, University of Papua New Guinea, and LIMS alumnus) and Professor Andrew Somogyi (Professor of Clinical and Experimental Pharmacology at the Adelaide Medical School, University of Adelaide), Dr Tucci is currently working on game-changing research that examines the impact of common HIV/AIDS treatments on PNG’s indigenous population.
HIV/AIDS in PNG
“HIV/AIDS is found in PNG at a rate of 2-3 times that of the global average,” said Dr Tucci. “In PNG, a relatively poor health infrastructure makes it more difficult to treat this problem. Another big problem is that of co-morbidities: because the immune system is compromised, it is common to see HIV/AIDS patients with tuberculosis, including multidrug resistant strains of the disease.”
The common treatment used to manage HIV/AIDS in PNG also has potentially catastrophic effects. “One of the drugs that is used in PNG has profound side effects including confusion, drowsiness, and psychotic episodes to the point of suicide,” explains Dr Tucci. “We have evidence that patients who carry a certain genetic mutation, in the CYP2B6 gene, are more likely to experience the serious side effects associated with this drug.”
Pilot studies by the research team have revealed that the CYP2B6 mutation is present in about 50-60% of carriers in PNG. “To put that into perspective, in some western countries it is found in about 10-20% of people,” said Dr Tucci. “In PNG, the indigenous population carry a higher level of this mutation than anywhere else in the world. Our findings hit home how crucial it is to do further research.”
The next stage of the project is being funded by the Australian Centre for HIV and Hepatitis Research. “We plan to recruit other physicians to take blood from patients so we can examine their DNA, identify the mutation, link it to actual levels of the HIV drug in their bodies, and correlate it to particular side effects.”