Researchers are making steady progress in the search for new mesothelioma treatments, and photodynamic therapy (or PDT) has shown a lot of promise. This type of treatment involves a drug ─ referred to as a photosensitizer or photosensitizing agent ─ that is given to a patient intravenously, absorbed into the body and then activated by a special light. When activated, the drug produces a type of oxygen that kills the cells around it, specifically cancer cells.
What makes photodynamic therapy ─ also known as photoradiation therapy, phototherapy, or photochemotherapy ─ such a promising treatment option for mesothelioma, apart from its effectiveness, is its relatively mild side effects. Intraoperative photodynamic therapy, in particular, is being studied as a way to directly target mesothelioma while the patient is undergoing surgery.
Although it has not yet been approved by the FDA for mesothelioma treatment, the photosensitizing agent porfimer sodium (also known as Photofrin) has been approved to treat esophageal cancer and non-small cell lung cancer. Mesothelioma patients can currently explore PDT treatment options through clinical trials.
How Photodynamic Therapy (PDT) Works
Photodynamic therapy for mesothelioma is not a one-step process. In fact, the photosensitizer drug alone will not make a difference without the light to activate it. According to the National Cancer Institute, the PDT treatment process works like this:
- First, a photosensitizing agent is injected into the patient. For intraoperative photodynamic therapy, the agent is injected before surgery.
- The body’s cells absorb the agent, but the drug stays in cancer cells longer than it stays in the body’s normal cells.
- In 24 to 72 hours, depending on the agent used, most of the drug passes through the body’s normalcells but lingers in the cancer cells.
- At this point, the cancer cells are exposed to the special light. The stretch of time between when a patient receives the drug and when the light is applied is known as the drug-to-light interval.
- For intraoperative photodynamic therapy, the surgery is timed based on when the drug has left the normal cells. The surgeon first removes as much of the mesothelioma tumor as possible, then uses the light to activate the agent in any mesothelioma cancer cells that may have been left behind.
- The light, which is often from a laser, can also be delivered through fiber optic cables inserted into the patient’s body with an
- When the photosensitizing agent in the cancer cells is exposed to the light, it produces a form of oxygen that destroys the cells.
- When activated by the light, the agent can also damage blood vessels in a tumor, cutting it off from nutrients.
- In addition, PDT maytrigger the immune system to attack the cancer cells, making it a possible combination treatment with immunotherapy for mesothelioma.
- Photodynamic therapy for mesothelioma may also be combined with radiation or chemotherapy.