Skip to main content
Skip to main menu Skip to spotlight region Skip to secondary region Skip to UGA region Skip to Tertiary region Skip to Quaternary region Skip to unit footer


Affibodies: Synthetic Protein Binders for Imaging HER2-Positive Breast Cancers

Cynthia Tope
Cynthia Tope
Chemistry Department
University of Georgia
Chemistry Building, Room 400
Analytical Seminar

HER2-positive breast cancers affect roughly 25% of patients and are extremely aggressive.

While treatments specifically targeting the HER2 receptors are quite successful, they require an

accurate diagnosis of HER2 overexpression. Current detection methods of immunohistochemical

staining (IHC) and fluorescent in situ hybridization (FISH) do not give a global view of the cancer. They

are limited to the metastases biopsied and may lead to misdiagnosis. While the use of antibodies as

specific protein binders is very useful for ex vivo detection methods such as IHC, their slow clearance

rate from non-specific tissue and high-blood retention limits their use in vivo, making HER2

quantification impossible. Ample research is being done to produce protein binders, such as affibodies,

that can overcome these limitations.

Affibodies are a classification of synthetic protein binders derived from the IgG binding domain

of Staphylococcal protein A. By varying thirteen specific residues of the parent protein, and through

additional affinity maturation, a second-generation affibody, denoted ZHER2, has been determined to

bind HER2 with high affinity (22 pM) using SPR. ZHER2 has also been shown to bind HER2 in a site

separate from that of drugs that target HER2, as shown in X-ray crystal structures. Through further

engineering of the Z-domain scaffold, ZHER2 has been better optimized to limit binding to IgG’s and

increase stability. ABY-025, the newly optimized affibody, has recently undergone phase I/II clinical

studies, where it has been shown to quantitatively determine HER2 expression in vivo, allowing for the

diagnosis of HER-positive metastases without the need for invasive biopsies.

Support Us

We appreciate your financial support. Your gift is important to us and helps support critical opportunities for students and faculty alike, including lectures, travel support, and any number of educational events that augment the classroom experience. Click here to learn more about giving.

Every dollar given has a direct impact upon our students and faculty.

Got More Questions?

Undergraduate inquiries: 

Registration and credit

AP Credit, Section Changes, Overrides,

Graduate inquiries:

Contact Us!

Assistant to the Department Head: Donna Spotts, 706-542-1919 

Main office phone: 706-542-1919 

Main Email:

Head of Chemistry: Prof. Jason Locklin