Innovative drug delivery system for photosensitizers in photodynamic therapy

Cancer is one of the main causes of death worldwide. One of the newer therapeutic approaches is photodynamic therapy (PDT), a treatment that uses a photosensitizing chemical substance, a particular type of light and oxygen. Each photosensitizer is activated by light of a specific wavelength and produces reactive oxygen that kills nearby target cells. One of the limitations of current PDT lies in the challenge of administering highly lipophilic anti-tumor photosensitizers. Though this can partly be overcome by suitable nanoparticle formulations and carrier systems, there remains the difficulty of release of the photosensitizer molecule from the carrier system. The compositions of the current invention by a German university and especially the used polymers address this problem by providing innovative biocompatible formulations which can be cleaved or degraded by light irradiation thereby releasing the photosensitizer molecules at the desired treatment site. The molecules thus released can then additionally be activated by light irradiation for photodynamic treatment. In addition due to their light-absorbing and -emitting properties these compounds may also be employed for diagnostic purposes e.g. by detecting their fluorescence. Technical Specifications: The present invention uses newly developed self-immolative polymers for nanoparticle manufacturing. Light-responsive polycarbonates (LrPC) as well as PEGylated LrPC (LrPC-PEG) were synthesized via ring-opening polymerization of trimethylene carbonate-based monomers and fully physico-chemically characterized. Lightresponsive nano formulations were obtained by blending LrPC or LrPC-PEG with the FDA-approved polymer poly(DL-lactide-co-glycolide) (PLGA). The nanoparticles were loaded with the photosensitizer 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (mTHPC). The German university offers a license agreement. Potential partners come from the pharmaceutical or chemical industry. If the company requires support in further development, the university will be happy to assist and offers a technical cooperation agreement to go along with it.