Optical monitoring of tumor angiogenesis

Tumors send chemical signals to the body to trigger angiogenesis to fuel their growth. These new vessels are hyperpermeable compared to normal, mature vessels. A new type of cancer treatment, anti-angiogenic therapy, inhibits the tumor´s ability to recruit new blood vessels, limiting tumor growth. When effective, these drugs lower the permeability of the tumor vasculature because the production of new, leaky vessels is reduced. Currently, only expensive imaging methods such as MRI and CT can be used to evaluate microvascular permeability. We have developed an optical system that is less expensive and portable. It can non-invasively monitor the dynamics of chromophores in vivo in the tumor by measuring the rapidly changing concentration of the dye over time. When these optical measurements of the first-pass kinetics are paired with a computational pharmacokinetic model, we can extract parameters related to the permeability of the tumor microvasculature. In this proof-of-concept demonstration, we present the data for two molecules of different molecular weight tagged with chromophores. The molecules were injected simultaneously into a live animal model. The data show that our system can differentiate between the dynamics of the two molecular weights and their ability to permeate into the tumor tissue from the microvasculature.