Professor Yoram Salomon

Professor The Dept. of Biological Regulation Weizmann Institute of Science 76100 Rehovot, Israel Phone: 972 8 934 3930 Fax: 972 8 934 4186 Home: 972 8 946 0351 Mobile: 972 54 433 7674

Cancer Therapy by Blocking the Tumor's Blood Supply using Vascular Targeted Photodynamic Therapy (VTP)

Current Research: The major subject of research in the lab deals with Vascular Targeted Photodynamic Therapy (VTP). This novel anti cancer treatment modality was developed in the last 15 years in collaboration with Professor Avigdor Scherz from the Department of Plant Sciences at the Weizmann. The treatment comprises of i.v infusion of Pd-bacteriochlorophyll based photosensitzers synthesized in the A. Scherz laboratory with concomitant illumination (760nm) of the target tumor for 15-20 minutes via interstitial optic-fibers. The cytotoxic superoxide & hydroxyl radicals locally generated, induce vacular damage (blood cloting and vasoconstriction) that block blood supply to the tumor within minutes, leading to focal tumor ablation within days and to healing within weeks. Only a single treatment session is required and drug clearance from the circulation is completed within minutes, circumventing patient's skin photo-toxicity. In preclinical studies we showed that the success rates of VTP in mice and rats are high (50-90%) and in case of failure a 2^nd treatment can be delivered with increased success rate. Tumor response and healing are associated with extensive immune response and with development of tumor resistance that may be applied in future long term therapy. Magnetic resonance imaging (MRI), based on photochemical generation of in-situ paramagnetic deoxyhemoglobin contrast was developed for online follow up of VTP progress. Clinical trials for therapy of prostate cancer and age related macular degeneration in collaboration with Steba Biotech are in progress.

A novel direction of treatment based on photodynamic ablation of a selected rat embryo as model for the treatment of ectopic pregnancy was recently reported.
A short update of recent studies is provided below.

Future Research will center on elucidation of the mechanism of VTP, its systemic immune based activity, design and testing of tumor vascular targeted drugs, and further development of photosensitized MRI based imaging.

VTP, Intravascular events:
The intravenously infused Pd-bacteriochlorophyll based photosensitizer drug (PS) encounters an illuminated blood vessel in the target tumor and is instantaneously excited, releasing an electron. The electron interacts with circulating molecular oxygen generating reactive oxygen species (ROS), mainly superoxide and hydroxyl radicals. These highly cytotoxic forms of oxygen induce local vascular photodamage, hypoxia (due to oxygen consumption resulting in acute vascular occlusion, vasoconstriction and local thrombi, altogether leading to blood stasis within minutes. The tumor becomes necrotic 24 hours later. The process of tumor eradication and healing is completed within a few weeks.

Research Update

VTP team 2005-8

List of Publications