The unfortunate reality is that there is currently no cure for mesothelioma—not a standalone therapy, combination of therapies, diets and other behavioral changes or the powers of prayer and positive thinking. However, doctors specializing in mesothelioma treatment frequently treat a patient with a combination of therapies, known as multimodal treatment, for very important reasons:
- Due to the relative lack of effectiveness of single-modality treatment in prolonging patient survival, the multimodal combination of treatments holds more promise for survival of malignant mesothelioma patients.
- The palliative—pain relief and management—impact of multimodal treatment, depending on a number of factors, has been shown to be effective in many cases.
Several types of mesothelioma treatment are in experimental stages. They include the following mesothelioma therapies:
Immunotherapy
Also referred to as biological therapy, immunotherapy is based on the theory that it is possible to mobilize the body’s own immune defenses against cancerous cells. Another name that often applies to this therapy is biological response modifiers (BRMs).
A variety of experimental immunology treatments
Several new experimental treatments try to enhance the immune system’s ability to combat malignant mesothelioma. These include:
- Gene therapy
- Using cytokine proteins such as interferons and interleukins
- Using immunotherapy in combination with chemotherapy and other treatments
Gene Therapy
Currently in clinical trials, gene therapy employs an adenovirus for delivery and a suicide gene is inserted directly into the tumor. This gene makes the cells sensitive to a normally ineffective drug, such as glanciclovir. Treatment with the drug then destroys those cells that are rapidly dividing— which are the cancer cells—and leaves the healthy cells unharmed.
In theory, this approach allows treatment to target the tumor specifically, as opposed to the actions of treatments such as chemotherapy that also kill healthy cells.
Cytokines — Interleukins (IL) and Interferons (IFN)
Cytokines are small proteins that occur naturally in the human body. They are similar to hormones and have specific effects on the behavior of other cells.
Interleukins (ILs)
In 1976 Dr. Robert Gallo (later head of the National Cancer Institute, and famous for his work on HIV) isolated a cytokine protein molecule called interleukin-2 (IL2). It is capable of stimulating the growth of immune system cells called T-cells. T-cells are sometimes called killer cells because they search out malignant or virally infected cells and kill them.
Using IL2 as a treatment for pleural mesothelioma is still in the experimental stages. However, researchers hope that injecting IL2 intra-pleurally will promote a significant anti-tumor response.
Interferons (IFNs)
Interferons are another type of naturally occurring cytokine proteins. However, in addition to enhancing the immune system they also provide the benefit of inhibiting the growth of malignant cells. Like interleukins, these immune system promoters are being tested to see if they help increase the body’s response to what is often an extremely resistant malignancy, mesothelioma.
The National Cancer Institute web site is a primary resource for information about the status of clinical trials using cytokines such as interleukins and interferon for mesothelioma.
Photodynamic
Photodynamic therapy (PDT) is a treatment method often used in combination with other treatments such as drugs or surgery. PDT uses light to kill cancerous cells. As is true with many of the approaches to slowing the growth of cancers or finding a cure, photodynamic therapy is still in an experimental stage for treatment of mesothelioma.
How photodynamic therapy works
Initially, the patient receives a photosensitizer which collects in cancerous cells but not in healthy cells. A photosensitizer is a drug which makes malignant cells vulnerable—sensitive—to light of specific wavelengths.
After the cells have been sensitized, fiberoptic cables are placed in the body (usually through open-chest surgery) in order to focus light of just the right frequency on the tumor. This causes the photosensitizer to produce a toxic oxygen molecule which kills the cell.
Angiogenesis
Cancer cells, like other cells in the human body, rely for their growth on a rich supply of blood. They must be surrounded by an effective network of capillaries and larger blood vessels that nourish the cells. The medical term for the process of developing this network is angiogenesis.
Unfortunately, fast-growing cancers are highly efficient at promoting angiogenesis:
- They produce angiogenesis promoters that create capillaries and a network of blood vessels around the tumor.
- Cancerous tumors are thus nourished with an increasing supply of oxygen-rich blood — growing and spreading quickly or metastasizing.
Understanding that angiogenesis is fundamental to the process of how tumors grow and metastasize, medical researchers started to investigate how they could slow down, stop or reduce angiogenesis. If they could do this, they reckoned, they could starve the tumor to death, or at least slow its growth significantly. The National Cancer Institute has created a teaching tool to better understand angiogenesis.