Spectroscopic Photoacoustic Molecular Imaging of Breast Cancer using a B7-H3-targeted ICG Contrast Agent

Abstract

Purpose: Breast cancer imaging methods lack diagnostic accuracy, in particular for patients with dense breast tissue, and improved techniques are critically needed. The purpose of this study was to evaluate antibody-indocyanine green (ICG) conjugates, which undergo dynamic absorption spectrum shifts after cellular endocytosis and degradation, and spectroscopic photoacoustic (sPA) imaging to differentiate normal breast tissue from breast cancer by imaging B7-H3, a novel breast cancer associated molecular target.Methods: Quantitative immunohistochemical staining of endothelial and epithelial B7-H3 expression was assessed in 279 human breast tissue samples, including normal (n=53), benign lesions (11 subtypes, n=129), and breast cancers (4 subtypes, n=97). After absorption spectra of intracellular and degraded B7-H3-ICG and Isotype control-ICG (Iso-ICG) were characterized, sPA imaging in a transgenic murine breast cancer model (FVB/N-Tg(MMTVPyMT)634Mul) was performed and compared to imaging of control conditions [B7-H3-ICG in tumor negative animals (n=60), Iso-ICG (n=30), blocking B7-H3+B7-H3-ICG (n=20), and free ICG (n=20)] and validated with ex vivo histological analysis.Results: Immunostaining showed differential B7-H3 expression on both the endothelium and tumor epithelium in human breast cancer with an area under the ROC curve of 0.93 to differentiate breast cancer vs non-cancer. Combined in vitro/in vivo imaging showed that sPA allowed specific B7-H3-ICG detection down to the 13 nM concentration and differentiation from Iso-ICG. sPA molecular imaging of B7-H3-ICG showed a 3.01-fold (P<0.01) increase in molecular B7-H3-ICG signal in tumors compared to control conditions.Conclusions: B7-H3 is a promising target for both vascular and epithelial sPA imaging of breast cancer. Leveraging antibody-ICG contrast agents and their dynamic optical absorption spectra allows for highly specific sPA imaging of breast cancer.

Ultrasound molecular imaging as a non-invasive companion diagnostic for netrin-1 interference therapy in breast cancer

“…Female transgenic breast cancer-bearing (N=30) FVB/N-Tg(MMTV-PyMT)634Mul/J mice (MMTV-PyMT) and female, transgene-negative control littermates (N=15) were used at 8 weeks of age for USMI and in vivo immuno-localization of netrin-1. At this point of disease progression, female MMTV-PyMT mice were bearing invasive mammary carcinoma 21 , 32 , 33 . For netrin-1 and Fc receptor blocking experiments, mice were injected 100 µg of NET1-H-mAb 24 h prior to imaging.…”

“…For netrin-1 immunostaining, a previously described IgG localization technique, here called IVIL, was applied, as standard ex vivo immunofluorescence staining was prevented by the specificity of NET1-H-mAb to native state netrin-1 as opposed to fixed netrin-1, which undergoes conformational changes and antigen masking during tissue fixation 32 . Targeted and control antibodies show passive accumulation in tumor tissues due to the enhanced permeability and retention effect and Fc-mediated molecular interactions 34 - 39 .…”

Photoacoustic Imaging for Management of Breast Cancer: A Literature Review and Future Perspectives

“…Xia et al [79] performed an in vivo PA imaging study with nude mice using biodegradable nanomaterial liposome-encapsulating ammonium bicarbonate (NH 4 HCO 3 ) as a PA contrast agent. Wilson et al [80] used antibody indocyanine green (ICG) conjugates in the spectroscopic PA imaging of transgenic murine breast cancer model to distinguish malignant breast tissue and normal breast tissue in mice.…”

Photoacoustic Imaging in Tissue Engineering and Regenerative Medicine

“…123,[174][175][176][177][178] While a standardized technique is required for PAI before its transition to routine clinical use, the current in-house prototypes have demonstrated promising results for a wide range of cancers such as breast, [179][180][181] cervical, 182 prostate, 183 skin, 184 thyroid, 185 and ovarian cancer. 157 PAI leverages vasculature imaging and functional information such as oxygen saturation for cancer detection, 178 progression, 186 characterization, [187][188][189][190][191] prognosis, and monitoring therapeutic efficiency of treatment. [192][193][194] Delivery vehicles for cancer therapy are equipped with different PA contrast agents for multimodal imaging for better diagnosis and staging of cancer.…”