Genetic testing could yield better results for HIV/AIDS treatment

According to the World Health Organisation, roughly 17 million people globally are living on Antiretrovirals (ARV). Around 36.7m are living with HIV and roughly 47% of those people have access to this life-saving medication, due to the high cost of treatment. This highlights the pressing need for healthcare providers to invest in and refine ARV treatment, for long-term, accessible and affordable treatment.

Biochemical pharmacologist Professor Collen Masimirembwa suggests a closer look at human genetics might be one way to improve ARV therapy. Prof Masimirembwa has spent much of his career pioneering forensic DNA and toxicology on the African continent and was the first to conduct molecular pharmacogenetic studies in African populations in 1993.

“Every medication follows the same process: ingestion, absorption, metabolism and expulsion. ARVs are no different. We now know certain genes make some patients more susceptible to more rapid absorption of ARV medications, while others process and absorb these medications more slowly based on their genetic predisposition,” says Masimirembwa.

Can we improve life-saving treatment?

ARVs include a broad range of medicines that fight the HIV virus at different life stages, prevent the HIV virus from multiplying, and thus limit the destruction of CD4 T cells. There are now over 30 ARVs on the market. It’s often a complicated cocktail of several different medications, tested and reviewed based on the patient’s response. Genetic profiling enables medical professionals to understand the genetic status of a patient, particularly genes that affect responses to ARVs.

This enables doctors to develop treatment plans and prescribe correct ARVs at appropriate doses to yield the best outcome. Additional benefits of such an approach will be cost effectiveness and ensuring better quality of life during treatment.

Genetics in action

As an example, 95% of patients with human leukocyte antigen allele HLA-B*57:01 have high risk for hypersensitivity to the ARV abacavir. Efavirenz, another ARV, depends on the enzyme CYP2B6 for its metabolism and elimination. Patients with low activity variants of CYP2B6 have shown 5-10-fold higher levels above the minimum toxic concentration or MTC. Concentration higher than the MTC has been associated with severe neuropsychiatric adverse effects including depression, suicidality, nightmares and liver toxicity.

“Genetic profiling approach will enable medical professionals to quickly find the best combination of ARVs for the patient and avoid costly trial and error. It will reduce the risk of unnecessary adverse drug reactions as result of incompatibility with the patient’s genetic profile. Not only can healthcare professionals modify the treatment, but also select the best alternative medicines, should patients not respond optimally to their current treatment.”

Benefits of a pharmacogenomics approach

Masimirembwa also believes the nature of pharmacogenomics-guided treatment will demand more engagement between medical personnel and patients, a process in which patients will be more engaged in the planning of their treatment. This means a positive change the in doctor-patient relationship towards better treatment outcome.

The second outcome of integrating genetic profiling in patient management, says Masimirembwa, will be increased cost-benefit and effectiveness of treatment. Costs of genetic testing or the alternative drugs might be higher, but will result in the best possible outcome for the patient. In many cases, where trial and error could incur both major costs and detrimental risk to the patient, pharmacogenomics profiling will align treatment appropriately.

As Masimirembwa explains, “The shift to precision public healthcare gives pharmacogenomics profiling another opportunity to positively improve treatment at population level. Knowledge that certain populations are at risk of certain pharmacogenetic variations could trigger or result in the presumptive ordering of a genetic test.”

Genetic testing in SA

Pharmacogenomics tests are now safe and simple – and available to the public. An example in South Africa is mygeneRx, a cheek swab DNA test that can be ordered online and conducted in the patient’s home.

Based on existing and emerging knowledge on the role of genetics in of disease, drug and treatment outcome, Masimiremba advises patients to take DNA tests.

“Well-informed treatment can be done in the fastest possible time as trial and error is reduced to a minimum, as well as the risks for adverse drug reactions. Both factors which will reduce cost of treatment and improve quality of life for the patient.”

For more information about pharmaocenomic testing, visit www.mygeneRx.co.za. To speak to an expert about pharmacogenomics testing, email michelleraphiri@gullanandgullan.com.

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