Use Instructions

PN 10232 Eagle V1.2 Instructions for Use Rev 1.0 Page 8 of 101

tissue specimens and surgical cavity, beyond what can be visualized based on conventional surgical and

imaging approaches, would provide surgeons with clinically useful real-time information. In patients

undergoing breast conserving surgery, the presence of cancer in the margin of the resected lumpectomy

and/or in the surgical cavity that is undetected by standard of care is a significant clinical challenge for

surgeons and pathologists, and a risk to patients. The Eagle V1.2 Imaging System, when used in

combination a cancer-specific contrast agent, can address these challenges by enabling real-time

fluorescence visualization of otherwise occult cancerous tissue.

Using blue-violet light excitation (405 nm), the Eagle V1.2 Imaging System can visualize protoporphyrin IX

(PpIX) fluorescence emitted by cancer cells in patients who have received aminolevulinic acid (ALA), a

non-fluorescent prodrug contrast agent, prior to surgery [1]. Metabolism of ALA in the body leads to the

selective accumulation of PpIX in cancer cells. Under the blue-violet excitation light emitted by the Eagle

V1.2 Imaging System, the red PpIX fluorescence from cancer cells is detected simultaneously against

background normal tissues (which do not produce significant levels of PpIX) autofluorescence thereby

producing a composite fluorescence image (or video) in which PpIX fluorescent cancer cells and tissues

appear red in color in contrast to healthy surrounding tissues comprised primarily of connective tissue,

which appear predominantly green in color; noting that adipose tissue can appear dull-brown in color in

fluorescence images of breast tissues.

1.4.1. ALA and Protoporphyrin (PpIX) Production

The ALA-induced accumulation of PpIX in cancer cells is what enables the Eagle V1.2 Imaging System to

visualize malignant tissues. The following section describes PpIX synthesis in malignant and healthy tissues

and how exogenous administration of ALA leads to selective accumulation of PpIX in cancer cells thereby

producing fluorescence contrast between cancer cells and surrounding healthy tissues using the Eagle

V1.2 Imaging System.

ALA is a naturally occurring, endogenous substance, which belongs to the group of sensitizers used in

photodynamic diagnosis. It is the first compound in the heme synthesis pathway. Heme biosynthesis

begins within the mitochondrion, where ALA synthase catalyzes the condensation of succinyl-CoA and

glycine to form ALA. Aminolevulinic acid dehydratase (ALAD) condenses 2 molecules of ALA to form the

monopyrrole PBG. PBG deaminase catalyzes the polymerization of 4 molecules of PBG to

hydroxymethylbilane. Hydroxymethylbilane is further metabolized to uroporphyrinogen I and III (by

uroporphyrinogen cosynthase). Uroporphyrinogen decarboxylase sequentially removes a carboxylic

group from the acetic side chains of each of the pyrrole rings to yield coproporphyrinogen.

Coproporphyrinogen oxidase removes a carboxyl group from the propionic groups on 2 of the pyrrole

rings to yield protoporphyrinogen IX. Protoporphyrinogen oxidase forms PpIX by removing 6 hydrogen

atoms from protoporphyrinogen IX. Finally, ferrochelatase mediates the insertion of ferrous iron into the

porphyrin macrocycle, forming heme. Heme biosynthesis is regulated by a negative feedback loop in

which ALA synthase mitochondrial transport is inhibited by heme. Administration of excess exogenous

ALA avoids the negative feedback control, and accumulation of PpIX occurs in target tissue.