Mesothelioma Clinical Trial Should Prove Worth of Photodynamic Therapy
July 18, 2014
Eli Glatstein, M.D., has touted the benefits of photodynamic therapy for decades, but not everyone was listening.
Maybe now they will.
Glatstein, vice chairman of the radiation oncology department at Penn Medicine, leads the first randomized clinical trial of photodynamic therapy (PDT) for pleural mesothelioma cancer and aims to prove its effectiveness.
“If the results confirm what we expect, this could be a very positive, significant step forward for treatment of this disease,” Glatstein told Asbestos.com. “If it doesn’t work like we think it will, there’s a lot of egg on our face.”
Glatstein was instrumental in landing a recent $8 million grant from the National Cancer Institute (NCI) that will fund a clinical trial to study the effects of PDT and Photofrin, the photo-sensitizing drug most often used with the procedure.
Researchers also will use the grant to explore the effects of PDT on the immune system, blood vessels surrounding the tumor and tumor cells.
The Roswell Park Cancer Institute in Buffalo, N.Y. will collaborate in the study.
Penn Medicine Longtime Leader
The Abramson Cancer Center at Penn Medicine is one of the few mesothelioma specialty centers that has used PDT for years as an adjuvant therapy with radical pleurectomy surgery and achieved impressive results.
“Our survival rates are considerably better than most other people report [in other studies],” Glatstein said. “But there are a lot of people who still don’t believe in PDT. They didn’t learn much about it in medical school. So there is a lot of distrust in it, except from the people who use it successfully. It’s one reason why this study is so important.”
Photodynamic therapy uses light energy to kill cancer cells. An injection of a photo-sensitizing drug lingers within cancer cells longer than in healthy cells. The laser light, which is wavelength specific, triggers a reaction to kill the cancer cells without harming the normal cells.
Glatstein said he hopes the new trial will include at least 100 mesothelioma patients over the next four years. All patients will undergo a pleurectomy, which removes the lining around the lung along with any visible tumor cells growing inside the chest cavity.
Patients in the study will be randomly put into two groups. Half the patients will receive an intraoperative PDT with a laser inserted into the chest cavity. Those patients will receive Photofrin about 24 hours before surgery. Both groups will receive post-operative chemotherapy.
First Randomized Trial Was Needed
Glatstein believes results will prove what he has observed for many years that PDT works by eliminating the microscopic cancer cells that remain after surgery has finished and that the majority of patients undergoing the procedure will live longer.
“Most places report median survival of 18 to 24 months now,” he said. “A large majority of our patients have lasted much longer, like 41 months.”
In a study two years ago at Penn Medicine, 31 patients with the epithelial cell type were among the study subjects. Their median survival was 41.2 months.
When seven more patients with either biphasic or sarcomatoid cell types were added, the median survival rate dropped to 31.7 months. However, no control group was included to contrast the results.
Glatstein works closely with Penn Medicine thoracic surgeon Joseph Friedberg, M.D., who performs pleurectomies on cancer patients, and Penn’s Chuck Simone, M.D., a radiation oncologist who administers PDT.
Lung Sparing Surgery at Penn Medicine
Penn Medicine also has been a strong proponent of using the lung-sparing pleurectomy for mesothelioma, in contrast to the more aggressive extrapleural pneumonectomy (EPP), which removes an entire lung.
The PDT comes with side effects that include skin and eye sensitivity for several weeks. Patients must stay away from any direct sunlight during that time. However, there also is often a shorter period of swelling of healthy tissues relative to swelling associated with EPP surgery.
“The PDT has been a part of our treatment regimen for many years, but a randomized trial like this is necessary to prove its efficacy,” Glatstein said. “If our data holds up, this procedure will catch on considerably, and that will help patients everywhere.”
Researchers plan to study the PDT process and exactly how it destroys the cancer cells, thanks to the funding grant. They will look at molecular pathways, trying to get a better understanding of why it works and gather ideas for how to improve it.
Glatstein was quick to point out that PDT is no cure for pleural mesothelioma, but only a way to improve upon currently accepted therapies.
“We believe that PDT can play a significant role in the management of mesothelioma,” he said. “It’s not a solution, but if used under the right circumstances, and used for the right problems and in the right way, we believe there is a significant benefit.”