Activity of intrapleural recombinant gamma-interferon in malignant mesothelioma

Twenty-two consecutive patients with malignant diffuse pleural mesothelioma were treated with recombinant gamma-interferon by the intrapleural route. Diagnosis was made by thoracoscopic examination and all cases were confirmed by the French Mesothelioma Panel of Pathologist. Patients were staged based on thoracoscopic examination and computed tomography (CT) scan: 12 patients were classified as Stage I and 10 were Stage II. A solution of gamma-interferon (40 X 106 U) was infused twice a week over 2 months. Every patient experienced fever. One patient had a Grade 2 leukopenia and one patient suffered from pleural empyema. Response evaluation was based on the following: (1) CT scan performed 2 weeks after treatment ended, and (2) repeat thoracoscopic examination with histopathologic verification in nine patients who had demonstrated a stabilization or a regression of the disease on CT scan. From the original group, 19 patients could be evaluated. Four complete thoracoscopic histopathologic responses and one partial response were observed in Stage I patients (56%). One partial response was observed in Stage II patients.