Fluorescent Affibody Molecule Administered In Vivo at a Microdose Level Labels EGFR Expressing Glioma Tumor Regions

Abstract

PurposeFluorescence guidance in surgical oncology provides the potential to realize enhanced molecular tumor contrast with dedicated targeted tracers, potentially with a microdose injection level. For most glioma tumors, the blood brain barrier is compromised allowing some exogenous drug/molecule delivery and accumulation for imaging. The aberrant overexpression and/or activation of epidermal growth factor receptor (EGFR) is associated with many types of cancers, including glioblastoma, and so the use of a near-infrared (NIR) fluorescent molecule targeted to the EGFR receptor provides the potential for improving tumor contrast during surgery. Fluorescently labeled affibody molecule (ABY-029) has high EGFR affinity and high potential specificity with reasonably fast plasma clearance. In this study, ABY-29 was evaluated in glioma versus normal brain uptake from intravenous injection at a range of doses, down to a microdose injection level.ProcedureNude rats were inoculated with the U251 human glioma cell line in the brain. Tumors were allowed to grow for 3–4 weeks. ABY-029 fluorescence ex vivo imaging of brain slices was acquired at different time points (1–48 h) and varying injection doses from 25 to 122 μg/kg (from human protein microdose equivalent to five times microdose levels).ResultsThe tumor was most clearly visualized at 1-h post-injection with 8- to 16-fold average contrast relative to normal brain. However, the tumor still could be identified after 48 h. In all cases, the ABY-029 fluorescence appeared to localize preferentially in EGFR-positive regions. Increasing the injected dose from a microdose level to five times, a microdose level increased the signal by 10-fold, and the contrast was from 8 to 16, showing that there was value in doses slightly higher than the microdose restriction. Normal tissue uptake was found to be affected by the tumor size, indicating that edema was a likely factor affecting the expected tumor to normal tissue contrast.ConclusionThese results suggest that the NIR-labeled affibody molecules provide an excellent potential to increase surgical visualization of EGFR-positive tumor regions.

Near‐infrared photoimmunotherapy targeting EGFR—Shedding new light on glioblastoma treatment

“…Therefore, Sexton et al and others, have recently investigated EGFRspecific affibody molecules, that are 20 times smaller than mAbs, labeled with IR800CW and revealed that the probe can successfully detect glioma margins. 21,[27][28][29] Interestingly, it was reported that there is a significantly higher accumulation of Affibody EGFR -IR800CW than cetuximab-IR680RD in the boundaries of glioma tumor, even though cetuximab has 30 times greater affinity for EGFR than affibody molecules. 27 Building on these findings, we went one step further and conjugated Z EGFR:03115 affibody molecules with the highly hydrophilic IR700DX via a maleimide group.…”

Affibody molecules as engineered protein drugs

“…37 To pave way for a cost efficient potential clinical program, it was demonstrated that even a corresponding microdose of an EGFR-specific Affibody molecule, denoted ABY-029, was sufficient for delineation of human glioma xenografts in nude rats. 39 It was furthermore shown that ABY-029 imaging outperformed the standard 5-aminioleuvulinic acid agent in a direct comparison in orthotopically implanted rats but also that the overall imaging analysis could be further improved if ABY-029 was added to the standard agents and both signals used. 40 To test the utility of ABY-029 and to address the challenge of translation of novel agents to the clinic with very limited funding, ABY-029 has been synthesized chemically to support a phase 0 clinical trial to obtain initial characterization of the molecule, supported by a single NIH grant.…”

Preclinical imaging of epidermal growth factor receptor with ABY‐029 in soft‐tissue sarcoma for fluorescence‐guided surgery and tumor detection

“…ABY‐029 is approved as an exploratory investigational new drug (eIND application 122681) by the US Federal Drug Administration and is currently being tested for FGS in phase 0 studies of several cancers at microdose administration levels . The main advantage of ABY‐029 as compared with larger antibody‐based targeting agents is that ABY‐029 has a significantly shorter plasma half‐life, measured in minutes to several hours, as compared with days, which would allow for administration and surgery to occur on the same day . In addition, ABY‐029 is not anticipated to cause any pharmacological response, given that no immunogenic side effects were observed during toxicity testing using doses equivalent to 1000 times the human microdose level .…”

“…1 The main advantage of ABY-029 as compared with larger antibody-based targeting agents is that ABY-029 has a significantly shorter plasma half-life, measured in minutes to several hours, as compared with days, which would allow for administration and surgery to occur on the same day. 1,2,[12][13][14][15][16] In addition, ABY-029 is not anticipated to cause any pharmacological response, given that no immunogenic side effects were observed during toxicity testing using doses equivalent to 1000 times the human microdose level. 1 However, the tissue distribution and clearance of ABY-029 in solid tumors compared with normal tissues are not well defined.…”