What if you grew up in a house that, at some point, will negatively affect your health?
Many Kenyans lived in public housing estates owned by quasi-State agencies and city and town councils whose roofing likely contained asbestos.
Mesothelioma is a rare but aggressive cancer that affects the lining of organs such as the lungs, heart, and abdomen.
Asbestos was the material of choice in the building industry because it was affordable, highly effective fire-retardant, and an excellent thermal insulator.
Kenyans who worked in the construction industry were also occupationally exposed to it.
Little did we know that exposure to asbestos fibers from damaged roofs and ceilings, or through our occupations, can cause fibrotic lung disease, lung cancer, and mesothelioma.
Of these three conditions, mesothelioma is the only one whose primary risk factor is asbestos exposure.
In 2020, the International Agency for Cancer Research data showed that 30870 patients had mesothelioma, and 26278 died.
Mesothelioma is a rare but aggressive cancer that affects the lining of organs such as the lungs, heart, and abdomen.
At advanced stages, the cancer spreads to other distant organs such as the liver, lungs, and bones.
Among the top five rare cancers globally, mesothelioma is the deadliest. (Figure 1 below).
In 2020, the International Agency for Cancer Research data showed that 30870 patients had mesothelioma, and 26278 died.
In the same year, Africa reported about 1119 new cases and 1038 deaths from mesothelioma. (Figure 2 below).
Compared to other countries, the incidences of mesothelioma in Africa are low, which can primarily be attributed to under- or misdiagnosis.
Also, the reported low incidences can be attributed to significant data gaps related to occupational exposure in African countries.
In the developing world, the mining and use of asbestos continue because it is an affordable and readily available raw material for building products.
There are two sub-types of mesothelioma, namely pleural and peritoneal.
Pleural mesothelioma affects the lining of the lungs, while peritoneal mesothelioma affects the peritoneum, which is the lining of the abdomen.
The former accounts for 80 percent of all mesothelioma cases, where 90 percent of patients die within five years.
In the coming years, we might see increased disease incidences because mesothelioma takes between 30 and 40 years to develop.
While the incidences of this disease are decreasing due to the asbestos ban in some countries, its mortality remains high because of late diagnosis and treatment resistance.
However, we might see increased disease incidences in the coming years because mesothelioma takes between 30 and 40 years to develop.
Second, as of 2013, over 125 million people globally were exposed to asbestos at workplaces.
This is because the use of asbestos is still permitted in most countries.
Only 69 countries, most of which are in the developed world, have banned asbestos.
Asbestos was banned in Kenya in 2006, but the country still pays a heavy price.
In the developing world, the mining and use of asbestos continue because it is an affordable and readily available raw material for building products.
Asbestos was banned in Kenya in 2006, but the country still pays a heavy price.
In 2016, a report by Standard newspaper showed that Kenya spends about 10 percent of its health budget on treating asbestos-related cancers.
This is because many residential houses and mainly government buildings contain asbestos, the primary risk factor for mesothelioma.
The treatment for mesothelioma depends on different factors, such as age and severity of the disease.
According to the then National Environmental Management Authority (NEMA) chief research officer, the human, health, and environmental cost of asbestos pollution is higher than replacing these rooftops.
In 2013, the Government of Kenya established the National Guidelines on Safe Management and Disposal of Asbestos as part of its commitment to safeguard human and environmental health and minimize the risk of asbestos exposure.
The treatment for mesothelioma depends on different factors, such as age and severity of the disease.
In most cases, mesothelioma is diagnosed at advanced stages, and therapy focuses on managing symptoms and prolonging the patient’s life.
Since the adoption of cisplatin chemotherapy in 2004, no other chemotherapy has been approved to treat mesothelioma.
Over the last three decades, the treatment modalities for mesothelioma included surgery, radiation, and chemotherapy.
However, for all these treatments, the outcomes are quite disappointing because they only marginally prolong the life of patients.
For instance, despite curative surgery, mesothelioma patients live for 12 to 21 months.
Moreover, since the adoption of cisplatin chemotherapy in 2004, no other chemotherapy has been approved to treat mesothelioma.
Cancer cells rely on different nutrients, such as glucose and amino acids, to grow and multiply.
In April 2023, at the annual American Association for Cancer Research (AACR) meeting, a new innovative therapy offered hope for malignant pleural mesothelioma patients.
Professor Szlosarek of the Barts Cancer Institute, United Kingdom, presented the results of a five-year randomized clinical trial involving a new drug called pegylated arginine deiminase (ADI-PEG20), which extends the median survival of mesothelioma patients compared to the current treatment regimen.
These results took work, as they are the accumulation of intensive research built on Professor Szlosarek’s discovery in 2006 as a doctoral student.
Cancer cells rely on different nutrients, such as glucose (the simplest form of carbohydrates) and amino acids (building blocks of proteins), to grow and multiply.
Only 69 countries, most of which are in the developed world, have banned asbestos.
Two decades ago, Szlosarek discovered that malignant mesothelioma cells lacked argininosuccinate synthase (ASS1), an enzyme responsible for arginine synthesis.
Arginine is an amino acid essential in several immunological, metabolic, neurological, and signaling processes.
As malignant mesothelioma cells lack ASS1, they cannot synthesize arginine.
Therefore, these tumors rely on arginine in blood circulation to fuel their growth.
The new drug, ADI-PEG20, works by depleting arginine from circulation (Figure 3 below), thereby starving mesothelioma tumors of an essential nutrient leading to tumor shrinkage, activation of tumor cell death, and prolonged survival of patients.
Arginine depletion is a novel strategy that can be exploited in treating other arginine-dependent tumors such as melanoma, lymphomas, sarcoma, and liver cancer.
Like in malignant mesothelioma, the ASS1 enzyme is depressed in these tumors, making them addicted to arginine circulating in the blood.
These tumors have high nutritional needs that cannot be satisfied with de novo arginine synthesis, forcing them to rely on external arginine supplies.
Therefore, the promising clinical trial results of ADI-PEG20 in malignant mesothelioma offer a platform for testing it in other arginine-dependent cancers.
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Dr Oria (PhD) is LEAD Fellow, Prof Janine Erler Research Group, Biotech Research and Innovation Centre – University of Copenhagen, Denmark.