The Influence of Domain Permutations of an Albumin-Binding Domain-Fused HER2-Targeting Affibody-Based Drug Conjugate on Tumor Cell Proliferation and Therapy Efficacy

Abstract

Human epidermal growth factor receptor 2 (HER2) is a clinically validated target for breast cancer therapy. Previously, a drug-fused HER2-targeting affinity protein construct successfully extended the survival of mice bearing HER2-expressing xenografts. The aim of this study was to evaluate the influence of the number and positioning of the protein domains in the drug conjugate. Seven HER2-targeting affibody-based constructs, including one or two affibody molecules (Z) with or without an albumin-binding domain (ABD), namely Z, Z-ABD, ABD-Z, Z-Z, Z-Z-ABD, Z-ABD-Z, and ABD-Z-Z, were evaluated on their effects on cell growth, in vivo targeting, and biodistribution. The biodistribution study demonstrated that the monomeric constructs had longer blood retention and lower hepatic uptake than the dimeric ones. A dimeric construct, specifically ABD-Z-Z, could stimulate the proliferation of HER2 expressing SKOV-3 cells in vitro and the growth of tumors in vivo, whereas the monomeric construct Z-ABD could not. These two constructs demonstrated a therapeutic effect when coupled to mcDM1; however, the effect was more pronounced for the non-stimulating Z-ABD. The median survival of the mice treated with Z-ABD-mcDM1 was 63 days compared to the 37 days for those treated with ABD-Z-Z-mcDM1 or for the control animals. Domain permutation of an ABD-fused HER2-targeting affibody-based drug conjugate significantly influences tumor cell proliferation and therapy efficacy. The monomeric conjugate Z-ABD is the most promising format for targeted delivery of the cytotoxic drug DM1.

Experimental HER2-Targeted Therapy Using ADAPT6-ABD-mcDM1 in Mice Bearing SKOV3 Ovarian Cancer Xenografts: Efficacy and Selection of Companion Imaging Counterpart

“…Experience with other scaffold proteins suggests that the biodistribution profile of ADAPT6-based drug conjugate might be improved by optimizing the molecular design of the construct [48] as well as the linkers between the domains [49] and between the protein and cytotoxic moieties [31,50]. This could further reduce the toxicity to normal organs and increase the therapeutic window.…”

Advances of Epigenetic Biomarkers and Epigenome Editing for Early Diagnosis in Breast Cancer

“…Affibodies are engineered scaffold proteins based on a three-helix bundle domain designed to bind with high affinity to desired targets and obtain affibody-drug conjugates [ 302 ]. Xia et al designed Z-M ADCN, a conjugate nanoagent self-assembled into nanomicelles, resulting in improved pharmacokinetics and in vivo targeting performance due to longer retention time in blood and higher drug accumulation in the tumor [ 303 ].…”

ICG-Dimeric Her2-Specific Affibody Conjugates for Tumor Imaging and Photothermal Therapy for Her2-Positive Tumors

“…4 These signaling pathways regulate cell proliferation, survival, migration, angiogenesis, and metastasis. 5,6 However, Her2 is specifically overexpressed in many types of malignant tumors, including breast, gastric, and ovarian. 7−10 Her2 overexpression enhances cell signal transduction and accelerates the growth and metastasis of tumors, resulting in faster disease progression and poor clinical prognosis for patients bearing Her2-positive tumors.…”

“…Her2 consists of an extracellular domain, transmembrane domain, and intracellular tyrosine kinase catalytic domain and functions by forming a homodimer or a heterodimer with itself or other proteins in the same family. , After Her2 dimerization, several intracellular signaling pathways are activated, such as phosphatidylinositol 3 kinase/Akt, Ras/mitogen-activated protein kinase, Janus kinase/signal transducer and activator of transcription, and phospholipase C pathways . These signaling pathways regulate cell proliferation, survival, migration, angiogenesis, and metastasis. , However, Her2 is specifically overexpressed in many types of malignant tumors, including breast, gastric, and ovarian. − Her2 overexpression enhances cell signal transduction and accelerates the growth and metastasis of tumors, resulting in faster disease progression and poor clinical prognosis for patients bearing Her2-positive tumors . Therefore, Her2 is considered a diagnostic and treatment target for these tumors …”