During photodynamic treatment (PDT) of cancer, a photosensitive drug is introduced and activated by light to induce cytotoxicity. While PDT offers great promise as a targeted cancer treatment, many attempts to use PDT in the clinic have been hindered by the complex dosimetry problem and lack of an accepted definition of dose, along with the techniques to measure it in vivo. A comprehensive approach to dosimetry would enable clinicians to optimize treatments for individual patients. The measurement of oxygen concentration during PDT is a particularly challenging problem due to real-time changes in oxygen demand and supply during the treatment.
Using a unique combination of magnetic and optical modalities, INO has developed and patented a technology platform that enables monitoring of photoactive species produced in (or via) photodynamic therapy (eg. reactive oxygen species). Magnetic-induced changes in the steady-state, time-resolved, and spectrally resolved emission of the drug can then be correlated to the oxygen/hypoxic status relevant to the reaction dynamics during treatment, potentially allowing the physician to adapt treatment to the patient response near real-time.
The magnetic field effects on optical properties of PDT sensitizers which combine both a “drug-probe” constituents have been demonstrated with custom designed agents, to extract and dynamically monitor the oxygenation and/or reactive oxygen species.