Phase I Clinical Study Using PDT and Surgery

Mesothelioma News

Foscan–Mediated PDT and Surgery May Prove Helpful for Pleural Mesothelioma Patients

April 18, 2003 — In a preliminary study, photodynamic therapy (PDT) was combined with either of two types of surgery to treat patients with pleural mesothelioma (Ann Thorac Surg 2003 Mar; 75(3): 952–9). Photodynamic therapy is a technique that uses light to kill cancerous mesothelioma cells. The patient receives a photosensitizing agent that collects in the cancerous cells but not in healthy cells. Foscan (meta–tetrahydroxyphenylchlorin, mTHPC) is a photosensitizer, which is a drug that makes the cancer cells vulnerable and sensitive to light of a specific wavelength. Laser light of that wavelength is focused on the sensitized cancer cells, causing their death.

Twenty–six patients with pleural mesothelioma completed the PDT treatment. Seven of these patients underwent an extrapleural pneumonectomy, which is the removal of portions of the lung, the parietal pleura (the lining of the lung), the pericardium (the lining of the heart) and the diaphragm. Nineteen patients had a pleurectomy, which involves removal of the pleura. Portions of the lung are not removed in a pleurectomy. All patients received Foscan injections before surgery, and light of specified wavelength after the main surgery.

The researchers worked with various dose levels of Foscan. The maximally tolerated dose was 0.1 milligrams per kilogram of Foscan in combination with 652 nanometers of light. Fourteen pleural mesothelioma patients had no complications. Two out of three patients who received high Foscan doses died. Others developed wound burns and skin photosensitivity.

The pleural mesothelioma study was considered a Phase I clinical trial. The object of such a trial is to find the best way to give a new treatment and how much of it can be given safely. Although the treatment has been tested in the laboratory and in animals, the side effects in humans are unknown at the beginning of the study. The researchers concluded that the results of the Phase I mesothelioma clinical trial warranted further studies with a somewhat larger group of patients (a Phase II study). They also pointed out that Foscan–mediated photodynamic therapy may allow some patients to undergo a lung–sparing pleurectomy rather than the more invasive extrapleural pneumonectomy.