Tumor therapy with hematoporphyrin derivative and lasers via a percutaneous fiberoptic technique: preclinical experiments.

Photodynamic therapy relies on uptake of a photosensitizer (hematoporphyrin derivative [HpD]) by tumor cells and subsequent interaction of the photosensitizer with penetrating light. This technique has been applied in multiple animal systems and several clinical trials. The therapeutic results in large, deep tumors are limited by poor uptake and distribution of the HpD and limited penetration of tumors by light, even at high wavelengths. In various experiments with mice, HpD was injected into tumors, and light was applied via laser fiberoptics inserted through a sheath catheter. Preliminary findings indicated that intratumoral injection enables excellent distribution of HpD in high concentrations, thus optimizing the sensitivity of the tumor cells. The sheath catheter and fiberoptics enable excellent distribution of light. Experiments with T-cell lymphomas demonstrated significant response of the tumors to the combination of intratumoral HpD and interstitial light application.