Kijanka MM, van Brussel ASA, van der Wall E, Mali WPTM, van Diest PJ, van Bergen En Henegouwen PMP, Oliveira S. Optical imaging of pre-invasive breast cancer with a combination of VHHs targeting CAIX and HER2 increases contrast and facilitates tumour characterization.
EJNMMI Res 2016;
6:14. [PMID:
26860296 PMCID:
PMC4747965 DOI:
10.1186/s13550-016-0166-y]
[Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/20/2016] [Indexed: 11/30/2022] Open
Abstract
Background
Optical molecular imaging is an emerging novel technology with applications in the diagnosis of cancer and assistance in image-guided surgery. A high tumour-to-background (T/B) ratio is crucial for successful imaging, which strongly depends on tumour-specific probes that rapidly accumulate in the tumour, while non-bound probes are rapidly cleared. Here, using pre-invasive breast cancer as a model, we investigate whether the use of combinations of probes with different target specificities results in higher T/B ratios and whether dual-spectral imaging leads to improvements in tumour characterization.
Methods
We performed optical molecular imaging of an orthotopic breast cancer model mimicking ductal carcinoma in situ (DCIS). A combination of carbonic anhydrase IX (CAIX)- and human epidermal growth factor receptor 2 (HER2)-specific variable domains of the heavy chain from heavy-chain antibodies (VHHs) was conjugated either to the same fluorophore (IRDye800CW) to evaluate T/B ratios or to different fluorophores (IRDye800CW, IRDye680RD or IRDye700DX) to analyse the expression of CAIX and HER2 simultaneously through dual-fluorescence detection. These experiments were performed non-invasively in vivo, in a mimicked intra-operative setting, and ex vivo on tumour sections.
Results
Application of the CAIX- and HER2-specific VHH combination resulted in an increase of the T/B ratio, as compared to T/B ratios obtained from each of these single VHHs together with an irrelevant VHH. This dual tumour marker-specific VHH combination also enabled the detection of small metastases in the lung. Furthermore, dual-spectral imaging enabled the assessment of the expression status of both CAIX and HER2 in a mimicked intra-operative setting, as well as on tumour sections, which was confirmed by immunohistochemistry.
Conclusions
These results establish the feasibility of the use of VHH ‘cocktails’ to increase T/B ratios and improve early detection of heterogeneous tumours and the use of multispectral molecular imaging to facilitate the assessment of the target expression status of tumours and metastases, both invasive or non-invasively.
Electronic supplementary material
The online version of this article (doi:10.1186/s13550-016-0166-y) contains supplementary material, which is available to authorized users.
Collapse