Photodynamic therapy with motexafin lutetium for rectal cancer: a preclinical model in the dog

Photodynamic Therapy of Inorganic Complexes for the Treatment of Cancer†

Photodynamic therapy (PDT) is a medicinal tool that uses a photosensitizer and a light source to treat several conditions, including cancer. PDT uses reactive oxygen species such as cytotoxic singlet oxygen (¹ O₂ ) to induce cell death in cancer cells. Chemotherapy has historically utilized the cytotoxic effects of many metals, especially transition metal complexes. However, chemotherapy is a systemic treatment so all cells in a patient's body are exposed to the same cytotoxic effects. Transition metal complexes have also shown high cytotoxicity as PDT agents. PDT is a potential localized method for treating several cancer types by using inorganic complexes as photosensitizing agents. This review covers several in vitro and in vivo studies, as well as clinical trials that reported on the anticancer properties of inorganic pharmaceuticals used in PDT against different types of cancer.

Intraoperative fluorescent spectroscopy and photodynamic therapy of recurrent pelvis minor tumors with local radiation damage

This work presents the results of performing intraoperative photodynamic therapy (IOPDT) on 22 patients with recurrent pelvic tumors

(cervical cancer – in 18 patients, cancer of the corpus uteri – in 3 patients, cancer of the anal canal – in 1 patient). Prior to the PDT procedure, the patients were injected with photolon photosensitizer (PS) at a dose of 1.0–1.1 mg/kg. After the injection of PS, local fluorescence spectroscopy of tumor lesions was performed to determine the accumulation of drug in various areas of tumors and healthy tissue. Intraoperative laser irradiation was carried out 3–5 hours after the photolon injection with light at 662 nm wavelength using "Latus-2" laser device with a power density of 140 mW/cm2and the density of light energy of 40–60 J/cm2, the number of irradiation fields was 3–5 depending on the anatomical features.

The follow-up period after surgical treatment combined with PDT was from 6 to 24 months. Analyzing the immediate results of the treatment, there were no undesirable events or increase in the number of postoperative complications compared to patients treated without IOPDT. Were registered: transient increase in ALT and AST levels – in 5 patients (13.6%), reduction of oxygenation during anesthesia – in 20 (90.9%), transient fevers in the postoperative period – in 7 (31.8%).

It was noted that IOPDT with photolon drug, while slightly extending the time of the operation, is well tolerated by patients and does not lead to an increase in the number of early postoperative complications or the length of hospitalization.

Advances in photodynamic therapy for gastrointestinal tumors and its propect

This paper reviews the photodynamic therapy for gastrointestinal tumors and its mechanisms, and describes the authors' experience with it. It is feasible and reasonable to use photodynamic therapy for gastrointestinal tumors. It is not in contradiction with PDT and traditional surgical treatment, chemotherapy, radiation and immune therapy, etc. The main mechanisms of photodynamic therapy for gastrointestinal tumors are to damage tumor microvasculature, induce cancer cell apoptosis, injure cancer cell membrane, and trigger immune reactions.

Quantitative comparison of tissue oxygen and motexafin lutetium uptake by ex vivo and noninvasive in vivo techniques in patients with intraperitoneal carcinomatosis

Near-infrared diffuse reflectance spectroscopy (DRS) has been used to noninvasively monitor optical properties during photodynamic therapy (PDT). This technique has been extensively validated in tissue phantoms; however, validation in patients has been limited. This pilot study compares blood oxygenation and photosensitizer tissue uptake measured by multiwavelength DRS with ex vivo assays of the hypoxia marker, 2-(2-nitroimida-zol-1[H]-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide (EF5), and the photosensitizer (motexafin lutetium, MLu) from tissues at the same tumor site of three tumors in two patients with intra-abdominal cancers. Similar in vivo and ex vivo measurements of MLu concentration are carried out in murine radiation-induced fibrosarcoma (RIF) tumors (n=9). The selection of optimal DRS wavelength range and source-detector separations is discussed and implemented, and the association between in vivo and ex vivo measurements is examined. The results demonstrate a negative correlation between blood oxygen saturation (StO(2)) and EF5 binding, consistent with published relationships between EF5 binding and electrode measured pO(2), and between electrode measured pO(2) and StO(2). A tight correspondence is observed between in vivo DRS and ex vivo measured MLu concentration in the RIF tumors; similar data are positively correlated in the human intraperitoneal tumors. These results further demonstrate the potential of in vivo DRS measurements in clinical PDT.