Hard-to-Find Therapy Fights Mesothelioma Tumors with Carbon Ions

Carbon ion therapy—a cancer treatment developed in California but currently only available outside the US—may have the ability to significantly slow down the growth and spread of pleural mesothelioma tumors.

Researchers at one of the world’s most experienced carbon ion therapy centers in Chiba, Japan shared that conclusion in a new article in the journal Oncotarget.

According to the new research, carbon ion beams directed at two lines of malignant mesothelioma cells in the lab “suppressed cell viability”. The addition of cisplatin, one of two primary chemotherapy drugs used in the treatment of mesothelioma around the world, “significantly enhanced its action.”

The news is likely to be both exciting and frustrating for American mesothelioma patients who do not yet have access to the therapy close to home.

Carbon Ions for Mesothelioma

Carbon ion cancer therapy involves using a particle accelerator to pummel a tumor with DNA-damaging carbon ions. It is similar to proton therapy, but has been shown to especially benefit patients with radiation-resistant tumors because carbon ions are heavier and carry more destructive energy.

Another potential advantage for mesothelioma treatment is that, unlike conventional radiation, carbon ion therapy carries a lower risk of damaging healthy surrounding tissues since most of the energy is dispersed as soon as the particles hit the cancer cells.

 

This could be especially useful for people with malignant mesothelioma since their tumors lie in close proximity to vital organs like the lungs and heart.

A New Approach to Mesothelioma Therapy?

In the new study, researchers with the National Institute of Radiological Sciences found that carbon ion particles aimed at mesothelioma cells had higher “relative biological effectiveness” (RBE) than conventional X-ray.

Their tests showed that, when bombarded with carbon ions, the mesothelioma cells produced more of the chemicals that trigger apoptosis (cell death) and autophagy (cell component breakdown).

The effects were enhanced at higher doses, and enhanced further still when combined with cisplatin. The combination also interrupted the normal replication cycles of these mesothelioma cells and inhibited the ability of cancer stem cells to form spheroids that can be the precursors of tumors.

The article concludes, “Carbon ion beam combined with [cisplatin] has superior potential to kill malignant mesothelioma cells…with enhanced apoptosis.”

Where to Find Carbon Therapy

If mesothelioma patients want to try carbon ion therapy, they will have to travel. Although the technology was developed in the 1970s at Lawrence Berkeley National Laboratory in California, there are not yet any US centers using it.

There are, however, active carbon therapy centers in Japan, Germany, Italy, China and Austria with more under construction. The National Institute of Radiological Sciences in Japan, where the new mesothelioma study was conducted, has treated more than 10,000 cancer patients with carbon therapy.

According to a 2017 article in Bioengineering Today, part of the holdup in the US is cost and competition for research funding. A carbon ion therapy center would cost more than $100 million dollars to build and would require significant testing to comply with FDA rules.

Nevertheless, the article’s author says the National Cancer Institute “now has a confirmed goal to make a carbon therapy instrument and treatment center in this country.” The University of Colorado conducted a feasibility study in 2014, but efforts to establish a carbon therapy facility are still ongoing.

Sources:

Sai, S, et al, “Effects of carbon ion beam alone or in combination with cisplatin on malignant mesothelioma cells in vitro”, March 13, 2018, Oncotarget

Blaustein, Richard, “The Future of Carbon Therapy”, May 26, 2017, Bioengineering Today