There is active research trying to find blood tests to help diagnose mesothelioma. Researchers are looking for chemicals that may come from mesothelioma cells and not normal cells. If a chemical from mesothelioma cells can be measured, it could indicate the presence of mesothelioma.More than one group of these chemicals has been found. Soluble Mesothelin-Related Peptides, or SMRP, have been studied for some time. Levels of SMRP are high in patients with mesothelioma. There is a blood test available to measure levels of SMRP called a Mesomark Assay. It is an Enzyme-Linked Immunosorbent Assay, or ELISA test. SMRP levels can be high in patients long before they are diagnosed with mesothelioma. It is hoped that this can become a useful screening test for patients at risk of mesothelioma – anyone with known asbestos exposure but with no symptoms.
At the current time it is not used for screening. It is only available as an FDA humanitarian-use device for the purpose of following patients treated for mesothelioma. Levels should drop after treatment, and can be watched to give an indication of whether or not the tumor is reoccurring or growing.
Because mesothelioma is a rare disease, sometimes devices that can only benefit a small group of people with the disease will be allowed in use without the same lengthy testing period normally required. When there are only a small number of affected patients, there will not be enough numbers to do the statistical analysis recommended. There may also not be the research money that would be provided for devices expected to help a lot of people. The FDA says:
“An Humanitarian Use Device (HUD) is a device that is intended to benefit patients by treating or diagnosing a disease or condition that affects or is manifested in fewer than 4,000 individuals in the United States per year. A device manufacturer`s research and development costs could exceed its market returns for diseases or conditions affecting small patient populations. The HUD provision of the regulation provides an incentive for the development of devices for use in the treatment or diagnosis of diseases affecting these populations.
To obtain approval for an HUD, an humanitarian device exemption (HDE) application is submitted to FDA. An HDE is similar in both form and content to a premarket approval (PMA) application, but is exempt from the effectiveness requirements of a PMA. An HDE application is not required to contain the results of scientifically valid clinical investigations demonstrating that the device is effective for its intended purpose. The application, however, must contain sufficient information for FDA to determine that the device does not pose an unreasonable or significant risk of illness or injury, and that the probable benefit to health outweighs the risk of injury or illness from its use, taking into account the probable risks and benefits of currently available devices or alternative forms of treatment. Additionally, the applicant must demonstrate that no comparable devices are available to treat or diagnose the disease or condition, and that they could not otherwise bring the device to market.
An approved HDE authorizes marketing of the HUD. However, an HUD may only be used in facilities that have established a local institutional review board (IRB) to supervise clinical testing of devices and after an IRB has approved the use of the device to treat or diagnose the specific disease. The labeling for an HUD must state that the device is an humanitarian use device and that, although the device is authorized by Federal Law, the effectiveness of the device for the specific indication has not been demonstrated.”
The FDA has only approved the Mesomark Assay to follow patients with known mesothelioma.
Osteopontin is also elevated in the blood of patients with mesothelioma. It is both a tumor marker and a potential way to diagnose the cancer. Research continues on both osteopontin and SMRPs.
Dr. Kaplan
