Intrapleural Administration of HSV1716 to Treat Patients With Malignant Pleural Mesothelioma.

HSV1716, an oncolytic virus, is a mutant herpes simplex virus (HSV) type I, deleted in the RL1 gene which encodes the protein ICP34.5. Malignant mesothelioma is an aggressive, asbestos-related tumour of the pleural and peritoneal cavities. It is a rare cancer which occurs in individuals who have been exposed to asbestos, although it typically occurs decades after exposure (10-40 years later). Malignant pleural mesothelioma forms plaques that are distributed on the surface of the pleural space in the lung. Approximately 30% of patients require an indwelling pleural catheter for drainage of pleural effusions. In this patient group, the indwelling catheter may be used to facilitate loco-regional delivery of HSV1716 to the pleural space. This study seeks to evaluate the safety and biological effects of single and multiple administrations of HSV1716 in the treatment of malignant pleural mesothelioma.

The study will be conducted in two parts. PART A is a single centre, single dose design, open label. Patients with inoperable malignant pleural mesothelioma will receive a single dose of HSV1716 by intrapleural administration. Delivery will be by direct administration via an indwelling catheter into the pleural cavity. PART B is a single centre, repeat dose design, open label. Two groups of three patients with inoperable malignant pleural mesothelioma will receive 2 (group 1) or 4 (group 2) single doses of HSV1716 at weekly intervals. Administration will be via an indwelling catheter into the pleural cavity.