The Latest Developments in Treatment of Mesothelioma

• Nancy Meredith
• Featured News

by Jennifer Schnalzer

Mesothelioma is an aggressive cancer that affects the membrane lining of the lungs and abdomen and is the most serious of all asbestos-related diseases. Asbestos refers to a set of six naturally occurring fibrous minerals that are extremely durable and resistant to fire and most chemical reactions and breakdowns (MCA, 2014). Most products today do not contain asbestos. However, asbestos was used in many building products and insulation materials in homes until about the 1970’s (CPSC, 2014) Therefore, asbestos still plays a major role in today’s society and more and more people are being diagnosed with mesothelioma due to asbestos exposure.

Studies show that people breathing high levels of asbestos fibers can lead to an increased risk of mesothelioma. Mesothelioma is a cancer that usually affects the thin, protective membrane of the chest surrounding the lungs, heart or abdominal cavity (Selby, 2014). In the United States, doctors diagnose between 2,000 and 3,000 new cases a year. Worldwide approximately 14,200 people are diagnosed a year and 43,000 people die from the disease annually (Selby, 2014).

Mesothelioma is a difficult cancer to treat and doctors are constantly trying to improve on current approaches. The three standard treatments used are surgery, radiation therapy and chemotherapy. Currently, the leading therapeutic approach for mesothelioma is called multimodal treatment, involving a combination of surgery, chemotherapy and radiation therapy (Selby, 2014). While each treatment option has their own benefits by itself, cancer specialists are opting for a more effective approach of combining treatments. Some patients are given chemotherapy and/or radiation therapies after surgery to kill any cancer cells that are left.

Since standard treatments often have limited usefulness against mesothelioma, researchers and doctors are studying new types of treatment. The research and treatments being performed in clinical trials and facilities across the world are leading doctors to more effective procedures for current and future mesothelioma patients (American Cancer Society, 2014). There may be tremendous potential with biologic therapy, gene therapy and photodynamic therapy. Even though these treatments are still in the clinical trial phase they could very well be the standard treatment in the future.

Biologic therapy, also known as, immunotherapy is a treatment that uses the patient’s immune system to fight cancer (NCI, 2013). When combines with the other anticancer treatments like chemotherapy, biologic therapy can improve survival rates and reduce symptoms for people with mesotheliomma. Even though it has not been able to cure the cancer, it can enhance the immune system response to mesothelioma cancer. Researchers have discovered a direct correlation between penetrating lymphocytes and mesothelioma prognosis, indicating that enhanced immune response may improve patient outcome (Selby, 2014). Some types of biologic therapy are referred to as vaccination therapy. One approach is to remove the immune cells from the patient’s blood and treat them in a lab to get them to react to tumor cells, the immune cells are then given back to the patients as blood transfusion, where it is hoped they will cause the body’s immune cell system to attack the cancer (American Cancer Society, 2014).

Other approaches of biologic therapy are the studies of drugs such as tremelimumab, ganetespib, and defactinib. The objective for these drugs is to help kill the cancers cells and prevent them from spreading. Tremelimumab is an antibody that blocks Cytotoxic T lymphocyte antigen4. CTLA4 is a protein found on the cells of the immune system, which may prevent immune cells from attacking cancer cells by slowing the immune response, allowing the cancer to grow and spread. Tremelimumab blocks the lymphocyte CTLA4 from slowing the immune system which enhances the immune response against mesothelioma (MSKCC, 2014). Ganetespib is a drug that is currently being tested to prevent mesothelioma tumors. Ganetespib inhibits heat shock protein 90, which is a protein in cells that is required in order for a tumor growth to occur. Tests have indicated that ganetespib is extremely active in mesothelioma and doctors seem to think that combined with chemotherapy this treatment could shrink cancers down and improve symptoms for patients (Leicester, 2013). Defactinib is another biological therapy drug being tested in clinicals. The clinical trial that is testing Defactinib is called COMMAND (Giulianotti, 2014). Defactinib is an oral drug that targets cancer stem cells by inhibitin the process of the protein focal adhesion kinase, which is needed for cancer stem cells to grow and survive. Defactinib is designed to stop the signals that the cancer cells use to divide and grow (Giulianotti, 2014). Defactinib is less toxic than chemotherapy and has fewer side effecting allowing it to be used for long periods of time to compat tumor stem cells and for maintenance (Povtak, 2013). Defactinib is proving to be a very promising treatment for mesothelioma and has been approved by the Food and Drug Administration in the treatment of mesothelioma (Povtak, 2013).

Researchers are exploring a newer type of treatment involving gene therapy to treat patients with mesothelioma. Gene therapy attempts to add new genes to cancer cells to make them easier to kill (American Cancer Society, 2014). One type of gene therapy targets cancer cells and auses them to die; this is called suicide gene therapy and is one of the most promising forms of gene therapy for treatment of mesothelioma (Selby, 2014). With the help of a virus, doctors introduce a protein-producing gene that converts a non-toxic drug into one that can kill cancer cells (Selby, 2014). Another type of gene therapy uses modified viruses to deliver immune system molecules called cytokines. Cytokines can help the immune system mount an attack against cancer cells (Selby, 2014). Early studies of gene therapy have found that it may shrink or slow the growth of mesothelioma in some people. However, because gene therapy is still in its infancy, the long-term side effects of the treatment remain unknown and more research is needed to determine if this treatment will truly work.

A newer therapy being used to treat mesothelioma is Photodynamic therapy, which uses light energy to kill cancer cells. First, a photosensitizer drug is injected into the patient. The main photosensitizer used for pleural mesothelioma treatment is porfimer sodium, usually called Photofrin (Selby, 2014). This drug is absorbed by cells and happens to remain in cancer cells longer. Therefore, after a few days when the photosensitizer has left many of the healthy cells, a special light is applied to the area, usually via laser, to activate the drug. The activated drug produces a highly reactive form of oxygen which affects all nearby cancer cells causing a reaction that kills the cancer cells (Selby, 2014). Photodynamic therapy has demonstrated positive results and is developing into a viable treatment option. Not only is photodynamic therapy less invasive with fewer side effects but it can also be used safely with other treatments to be more effective in increasing life expectancy (Mesothelioma Guide, 2014).

Even though there is still no cure for mesothelioma, advances in treatment offer hope for those affected by mesothelioma. Mesothelioma patients are living longer than ever before, benefiting from the advancement in treatment and the personalized care they receive at specialty centers across the country. More accurate diagnostic tools, better chemotherapy drug combinations and improved surgical techniques all play a role in the treatment progress. As research and experiments continue, the newer forms of treatment involving biologic therapy, gene therapy, and photodynamic therapy may become the first line of treatment for mesothelioma in conjunction with the standard treatments. With the developments of the new treatments, many doctors hope to give patients with mesothelioma a better quality of life and increase life expectancy and to maybe one day actually find a cure.

REFERENCES

• American Cancer Society (2014) What’s New in Malignant Mesothelioma Research and Treatment?
  http://www.cancer.org/cancer/malignantmesothelioma/detailedguide/malignant-mesothelioma-new-research
• Consumer Product Safety Comission: CPSC (2014). Asbestos In The Home
  http://www.cpsc.gov/en/Safety-Education/Safety-Guides/Home/Asbestos-In-The-Home/
• Dr Giulianotti, Dan (2014). Will Mesothelioma Finally Meet Its Match?
  http://www.mesocare.org/verastem-mesothelioma-treatment/
• MSKCC: Memorial Sloan Kettering Cancer Center (2014). Phase II Study of Tremelimumab versus Placebo for Previously Treated Inoperable Mesothelioma
  http://www.mskcc.org/cancer-care/clinical-trials
• NCI: National Cancer Institute: (2013). Malignant Mesothelioma Treatment
  http://www.cancer.gov/cancertopics/pdq/treatment/malignantmesothelioma/patient/
• Povtak, Tim (2013). New Clinical Trial Tests Drug to Control Cancer Stem Cells.
• Selby, Karen (2014). Mesothelioma. The Mesothelioma Center
• University of Leicester (2013). Mesothelioma: Two groundbreaking trials into treatments for asbestos-related cancer. Science Daily
  https://www.sciencedaily.com/releases/2013/09/130923092748.htm