Mutated genes: Why targeted therapy is the future of cancer management


Oncogenetic analysis of female patients having a breast cancer risk and/or ovary cancer risk. PHOTO | CENTRE OSCAR LAMBRET | PHANIE

Cancer is the third-leading cause of death after infectious and cardiovascular diseases in Kenya and therefore prevention, early diagnosis and exploring new treatment options are critical to improve the survival of cancer patients. Personalised medicine in oncology comes in as a new therapeutic approach, which involves finding the right treatment, for the right patient and at the right time. It incorporates not only differences in cancer types and stages but also the subcellular biological differences in cancer cells, their organ of origin and genes.

What is targeted therapy?

Targeted therapy is a newer form of cancer treatment that is distinct from chemotherapy and radiotherapy. The basis of targeted treatment is that cancer cells normally have one or more mutated genes that drive the growth of cancer cells, and facilitate their escape from physiological regulation and the body’s immune system.

Using this knowledge, we can use uniquely designed drugs, antibodies or hormones to block the uncontrolled activity of mutated genes. An example is lung cancer. About 15 to 50 percent of lung cancers may have mutations in a gene called Epidermal Growth Factor Receptor.

This leads to continuous and autonomous activation of growth signals, favouring cancer growth. Similar therapies are also available for other cancers. The number of targetable mutations in various genes is numerous and the number of available targeted therapies is growing rapidly. Conveniently, a good number are available in tablet form.

What process is involved in targeted therapy?

The journey for a cancer patient diagnosis begins with a tissue biopsy or blood samples which comes to us in the lab. We will perform a microscopic analysis and define what we call a histologic diagnosis. Then we identify if there are mutated genes in that patient’s cancer that are driving its growth.

To achieve this, we perform specialised molecular tests. With this profile, we then match the patient to a specific therapy that may already be approved or is in clinical trials.

What is molecular testing and how is it performed?

In molecular oncology testing, we analyse molecules such as DNA, RNA and proteins from diverse patient samples. The aim is to determine whether there are abnormal genes that may be responsible for the disease in question - in this case, cancer.

These tests are used to arrive at a more specific diagnosis, match patients to specific therapies and monitor response to therapy. There are several platforms and technologies for performing molecular testing.

At Aga Khan University Hospital, we have introduced platforms that allow us to perform molecular testing on some of the common cancers, with the intention of targeted therapy. Molecular oncology testing is also very useful in identifying patients or families suspected to have hereditary cancer syndromes.

These patients and affected kin need a special-heightened cancer screening protocol, aimed at early diagnosis.

What are the advantages of adopting these types of diagnostics?

It is a game changer in the field of targeted therapy because it is increasing access to molecular testing. We have realised some significant advantages.

Specifically, we have reduced the turn-around time; previously, it would take two to four weeks to get results. With the new service, we can get results within a few days and sometimes, some hours.

Secondly, by eliminating logistical costs, we gain a price reduction for the patient. Thirdly, I believe that this is building local capacity for advancements in health care services in the country.

What are the challenges to targeted therapies and what solutions would you propose?

We still need additional equipment to expand the scope of testing, these are expensive, and so are the targeted therapies. To capitalise on economies of scale, developing centres of excellence in the African region where high volumes of quality testing and therapy is offered, makes more sense than working in small silos.

Improved access to high-quality pathology diagnostics, molecular testing and therapy should go hand-in-hand. Building a realistic and sustainable programme between the government, private sector, health insurance companies, patient advocacy partners and industry players is key.

Dr Njau is a Consultant Anatomic & Molecular Pathologist at Aga Khan University Hospital, Nairobi.

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