A groundbreaking study of an innovative treatment published in February this year in the JAMA Oncology, a peer-reviewed medical journal, brings long-awaited advancements in mesothelioma research. The international research team found that chemotherapy combined with a drug called ADI-PEG20, also known as pegargiminase, has the potential to prolong the life expectancy of patients treated with pleural mesothelioma. Although it needs to be studied more thoroughly, pegargiminase-based chemotherapy is one of the most promising emerging treatments for mesothelioma patients.

Mesothelioma is an aggressive and mostly deadly cancer that develops in the membrane around the lungs, abdomen, heart, or reproductive organs, called the mesothelium. Pleural mesothelioma, the most common type, starts in the tissues covering the lungs. The disease is almost exclusively caused by asbestos exposure, a strong, heat-resistant mineral fiber naturally occurring in rock and soil. Asbestos was widely used for its heat-resistant and insulating properties across the country by the construction and automotive industries and the military until the early 1970s, when its carcinogenic nature started to surface. Even though the use of asbestos has declined since the 1970s and 1980s, the first Federal ban against it was only introduced recently. In March of this year, the Environmental Protection Agency (EPA) banned chrysotile asbestos, the most common form of it. However, several types of asbestos are currently still imported and used by manufacturers in the U.S.

Hundreds of thousands of people have lost their lives already because of asbestos exposure, and many continue to be at risk of inhaling asbestos fibers by being in contact with disturbed asbestos-containing material (ACMs). The most affected individuals are construction and industrial workers, especially those from the automotive industries, military veterans, and military and civilian firefighters. Even though veterans make up less than 10 percent of the population, they comprise roughly 30 percent of Americans with mesothelioma. This is because the military, especially the Navy, has used large quantities of asbestos-containing material in its shipyards and ships for decades. Firefighters face elevated asbestos exposure during rescue and firefighting operations. During a fire or demolition, asbestos releases dust fibers that firefighters inhale or swallow. Asbestos fibers do not dissolve in the body and cause malignant illnesses, such as mesothelioma, many years later.  

Pegargiminase-based chemotherapy: a significant medical advancement

In most cases, the only treatment option for mesothelioma patients is chemotherapy because the illness is often only diagnosed at a late stage when surgery is impossible. The main reason for late diagnosis, on the one hand, is that mesothelioma symptoms are very similar to the symptoms of other, more common illnesses, such as lung cancer. On the other hand, the disease lingers in the body from 10 to 50 years before it shows any signs. Another frequent issue when it comes to mesothelioma treatment is that patients are often given an incorrect diagnosis. A medical study revealed that, generally, about half of pleural mesothelioma patients receive incorrect disease stage diagnostics, most being at a more advanced stage than initially thought. Mesothelioma is hard to treat, especially if it is discovered late. Even with traditional chemotherapy, it is difficult to contain mesothelioma's rapid progression.

The novel pegargiminase-based chemotherapy treatment for pleural mesothelioma patients opens up a new era in cancer research. The researchers combined the ADI-PEG20 medication with chemotherapy and tested the approach in a large-scale trial study. The study occurred at 43 sites in 5 countries between August 2017 and August 2021. The 249 involved patients were randomly assigned to receive either ADI-PEG20 or a placebo in addition to standard chemotherapy. On average, patients who received ADI-PEG20 lived 9.3 months, compared to 7.7 months for those on placebo. Also, patients on ADI-PEG20 experienced a delay in disease progression, lasting 6.2 months, compared to 5.6 months for those on placebo. Thus, the study shows a 1.6-month increase in the median overall survival of the patients. This is truly an extremely important discovery. With the application of ADI-PEG20, the researchers found a new way of destroying cancer cells by removing arginine, an amino acid responsible for helping cancer cells grow and survive.    

Rising death tolls call for action

The number of patients diagnosed with asbestos-related diseases, such as mesothelioma, lung cancer, and asbestosis, has been increasing in the past decades because of the long latency period between exposure and the illnesses' discovery. Mesothelioma is claiming many lives. While the exact death toll is unknown, the Environmental Working Group (EWG), based on national government data, calculated that 12,000 to 15,000 Americans die every year because of asbestos exposure, from which the number of mesothelioma deaths is about 2,848 a year. In all, the EWG estimates that from 1999 to 2017, 236,981 to 277,654 Americans died from asbestos exposure. A comprehensive study of asbestos-caused deaths published by The Institute for Health Metrics and Evaluation (IHME) shows a sharp increase compared to the estimates by the EWG. According to the IHME, 40,764 Americans died from asbestos-related diseases in 2019. 

This unprecedented medical trial has given our doctors a promising toll and mesothelioma patients a new hope to fight the disease. However, scientists must continue to test it to ensure it’s well studied before approval, and they need our policymaker's support. Extensive investment in mesothelioma research is more critical than ever. Companies linked to asbestos and other toxic chemical pollution have enjoyed laws favorable to them for too long, while our veterans, firefighters, and construction workers put their lives daily in danger for the well-being of their fellow citizens. Many now suffer from mesothelioma. It is time to invest more in a toxic-free future and in more research to achieve better cancer treatment.