Sensitive in vivo Visualization of Breast Cancer Using Ratiometric Protease-activatable Fluorescent Imaging Agent, AVB-620.

With the goal of improving intraoperative cancer visualization, we have developed AVB-620, a novel intravenously administered, in vivo fluorescent peptide dye conjugate that highlights malignant tissue and is optimized for human use. Matrix metalloproteinases (MMPs) hydrolyze AVB-620 triggering tissue retention and a ratiometric fluorescence color change which is visualized using camera systems capable of imaging fluorescence and white light simultaneously. AVB-620 imaging visualizes primary tumors and demonstrated high in vivo diagnostic sensitivity and specificity (both >95%) for identifying breast cancer metastases to lymph nodes in two immunocompetent syngeneic mouse models. It is well tolerated and single-dose toxicology studies in rats determined a no-observed-adverse-effect-level (NOAEL) at >110-fold above the imaging and estimated human dose. Protease specificity and hydrolysis kinetics were characterized and compared using recombinant MMPs. To understand the human translation potential, an in vitro diagnostic study was conducted to evaluate the ability of AVB-620 to differentiate human breast cancer tumor from healthy adjacent tissue. Patient tumor tissue and healthy adjacent breast tissue were homogenized, incubated with AVB-620, and fluorogenic responses were compared. Tumor tissue had 2-3 fold faster hydrolysis than matched healthy breast tissue; generating an assay sensitivity of 96% and specificity of 88%. AVB-620 has excellent sensitivity and specificity for identifying breast cancer in mouse and human tissue. Significant changes were made in the design of AVB-620 relative to previous ratiometric protease-activated agents. AVB-620 has pharmaceutical properties, fluorescence ratio dynamic range, usable diagnostic time window, a scalable synthesis, and a safety profile that have enabled it to advance into clinical evaluation in breast cancer patients.

Intraoperative Tumor Detection Using a Ratiometric Activatable Fluorescent Peptide: A First-in-Human Phase 1 Study.

BACKGROUND: Positive surgical margins remain a significant challenge in breast cancer surgery. This report describes the use of a novel, first-in-human ratiometric activatable cell-penetrating peptide in breast cancer surgery. METHODS: A two-part, multi-institutional phase 1 trial of AVB-620 with a 3+3 dose escalation and dose-expansion cohorts was conducted. The patients received an infusion of AVB-620 2-20 h before planned lumpectomy/mastectomy and sentinel node biopsy/axillary dissection. Imaging analysis was performed on images obtained from the surgical field as well as post-excision surgical specimens. Pathology reports were obtained to correlate imaging results with histopathologic data. Information on physical adverse events and laboratory abnormalities were recorded. RESULTS: A total of 27 patients received infusion of AVB-620 and underwent surgical excision of breast cancer. The findings showed no adverse events or laboratory values attributable to infusion of AVB-620. The 8-mg dose was selected from the dose-escalation cohort for use with the expansion cohort based on imaging data. Region-of-interest (ROI) imaging analysis from the 8-mg cohort demonstrated measurable changes between pathology confirmed tumor-positive and tumor-negative tissue. CONCLUSION: Intraoperative imaging of surgical specimens after infusion with AVB-620 allowed for real-time tumor detection. Infusion of AVB-620 is safe and may improve intraoperative detection of malignant tissue during breast cancer operations.

Characterization of voltage-gated sodium-channel blockers by electrical stimulation and fluorescence detection of membrane potential.

Voltage-gated ion channels regulate many physiological functions and are targets for a number of drugs. Patch-clamp electrophysiology is the standard method for measuring channel activity because it fulfils the requirements for voltage control, repetitive stimulation and high temporal resolution, but it is laborious and costly. Here we report an electro-optical technology and automated instrument, called the electrical stimulation voltage ion probe reader (E-VIPR), that measures the activity of voltage-gated ion channels using extracellular electrical field stimulation and voltage-sensitive fluorescent probes. We demonstrate that E-VIPR can sensitively detect drug potency and mechanism of block on the neuronal human type III voltage-gated sodium channel expressed in human embryonic kidney cells. Results are compared with voltage-clamp and show that E-VIPR provides sensitive and information-rich compound blocking activity. Furthermore, we screened approximately 400 drugs and observed sodium channel-blocking activity for approximately 25% of them, including the antidepressants sertraline (Zoloft) and paroxetine (Paxil).