Ruc-GFP Fusion Construct
Genelux scientists have incorporated Ruc-GFP, a luminescent fusion protein, into the Genelux platform technology (GL-ONC1) to enable non-invasive cancer diagnosis, staging and monitoring. This particular protein is a combination of two proteins: one bioluminescent derived from glowing sea pansies, and one fluorescent protein from jellyfish.
The pictures (above) show the effect of GL-ONC1 when administered to female nude mice. The breast cancer became infected with the intravenously (i.v.) delivered vaccinia virus, which can be detected by optical imaging as green fluorescence in the presence of blue excitation light.
The boundary of the tumors is clearly visible, allowing distinction between tumorous tissues and non-tumorous tissues. One clinical application is fluorescent marking of tumor margins by the engineered virus, assisting surgeons during tumor removal procedures. Over time, the breast tumors are eradicated by the virus, and the green fluorescence signal also disappears. The same green fluorescence signal can also be used to mark tumors in live animals (see below) after being injected with GL-ONC1. Once marked, the antitumor therapeutic outcome can be monitored noninvasively in real time.
Preclinical Breast Cancer Study
In a pivotal preclinical study published by Genelux scientists in Cancer Research (October 2007), human breast cancer tumors colonized by GL-ONC1 exhibited growth, inhibition, regression through complete eradication in 130 days in 95% of mice tested, and results were monitored utilizing GFP light emission. Below are images of a tumor 14 days, 28 days and 56 days after the virus has been injected into the bloodstream of a mouse against a control mouse whose tumor is untreated.
Ongoing human clinical trials involving GL-ONC1 may similarly utilize this optical imaging capability to provide early visual evidence of therapeutic effect/efficacy (surface or near-surface tumor colonization followed by shrinkage or elimination) in cancer patients. (Such findings would be considered secondary outcomes in a Phase I study focused on Safety and Dose Escalation, and would likely be confirmed in subsequent tumor biopsies).
Genelux scientists are continuing to test a variety of fluorescent proteins, because true deep-tissue imaging in whole mammals has been constrained by limitations below certain tissue “depths.” (Light emission/detection is hindered by absorbance of light by hemoglobin and the autofluorescence of the body tissue).