Intrapleural photodynamic therapy: results of a phase I trial

The management of pleural neoplasms, specifically mesothelioma, remains difficult. We performed a phase I trial in 54 patients with isolated hemithorax pleural malignancy to determine (a) the feasibility of intraoperative, intrapleural photodynamic therapy after debulking surgery; (b) the influence of light dose/sensitizer interval on postoperative morbidity in order to define the photodynamic therapy (PDT) maximal tolerated dose (MTD); and (c) whether first order dosimetry could be applied to this complex geometry.

Cohorts of three patients were given escalating intraoperative light doses of 15-35 J/cm2 48 h after i.v. delivery of 2.0 mg/kg Photofrin II (Quadra Logic Technologies, Vancouver, British Columbia, Canada), and then escalating light doses of 30-32.5 J/cm2 after a 24-h sensitizer/operation interval. Twelve patients could not be debulked to the prerequisite 5 mm residual tumor thickness. The remaining 42 patients underwent 19 modified pleuropneumonectomies, five lobectomy-pleurectomies, and 18 pleurectomies. Intrapleural PDT was delivered using 630 nm light from two argon pump-dye lasers, and real-time and cumulative light doses were monitored using seven uniquely designed, computer-interfaced photodiodes.

There was one 30-day mortality from intraoperative hemorrhage. In the 48-h sensitizer/operation group (n = 33), possible PDT-related complications included an empyema with late hemorrhage in one of three patients at 17.5 J/cm2 and a bronchopleural fistula at 35 J/cm2. At each of these light doses, three additional patients were treated without complication. Two patients subjected to 24-h sensitizer dosing and 32.5 J/cm2 developed esophageal perforations after pleuropneumonectomy at identical sites. The MTD was declared as 30 J/cm2 light with a 24-h dosing interval when none of the six patients (three original, three repeat) at that level developed toxicity.

These data demonstrate that resection and intrapleural PDT can be performed safely with currently available sensitizers and lasers. Phase II and III trials are now warranted at this MTD in a homogeneous population of patients with pleural malignancies.