Design, Synthesis, and Evaluation of a Neurokinin-1 Receptor-Targeted Near-IR Dye for Fluorescence-Guided Surgery of Neuroendocrine Cancers

Abstract

The neurokinin-1 receptor (NK1R) is implicated in the growth and metastasis of many tumors, including cancers of the brain (e.g. gliomas, glioblastomas, astrocytomas), skin (e.g. melanomas), and neuroendocrine tissues (cancers of the breast, stomach, pancreas, larynx and colon). Because overexpression of NK1R has been reported in most of these malignancies, we have undertaken to design an NK1R-targeted near infrared (NIR) fluorescent dye for fluorescence guided surgeries of these cancers. We demonstrate here that an NK1R-binding ligand linked to the NIR dye LS288 selectively accumulates in NK1R-expressing tumor xenografts with high affinity (Kd = 13 nM), allowing intra-operative imaging of these cancers in live mice. Because tumor accumulation is nearly quantitatively blocked by excess unlabeled ligand, and since NK1R negative tumors and normal tissues display virtually no uptake, we conclude that the observed tumor retention is NK1R mediated. Results on the synthesis, in vitro characterization, and animal testing of NK1R-targeted NIR dye are presented.

Small molecule targeted NIR dye conjugate for imaging LHRH receptor positive cancers

“…Fluorescence-guided surgery is an effective way to improve the surgical outcome and patient survival. Currently, there are multiple NIR dye conjugates targeted to various receptors such as the folate receptor, [33, 34] PSMA, [35] CAIX, [36–38] CCK2R, [39–41] and NK1R [42] etc. Despite the availability of these targeted NIR dye conjugates, many cancers cannot be imaged either due to the complete absence of or presence of only very low number of these receptors.…”

Use of a Single CAR T Cell and Several Bispecific Adapters Facilitates Eradication of Multiple Antigenically Different Solid Tumors

“…To evaluate the binding affinity of each CAM for both the anti-FITC scFv on the CAR T cell and its tumor antigen on the cancer cell, FITC-folate, FITC-DUPA, FITC-AZA, or FITC-NKRL were prepared and characterized as previously described (13,14,16,19). Because our transduced CAR T cells expressed GFP (as a means of evaluating CAR transduction efficiencies), we quantitated CAM binding to the CAR T cells by analyzing displacement of FITC-AlexaFluor647 (FITC-Alexa647) from the anti-FITC CAR T cells by each FITC-labeled CAM.…”

“…Finally, to evaluate the potency of the anti-FITC CAR T-cell therapy in a different tumor model, HEK293 cells were transformed with FRa, PSMA, CA IX, or the neurokinin 1 receptor (NK1R), that is often overexpressed on neuroendocrine cancers (13). Following selection of subclones that expressed significant Fig.…”

“…In the absence of such a bispecific adapter, CAR T-cell engagement with the cancer cell would not occur, and the consequent killing of the cancer cell would not proceed. More importantly, with the increasing availability of low-molecular-weight tumor-specific ligands (13)(14)(15)(16)(17), a cocktail of orthogonal fluorescein-linked bispecific adapters could be prepared in which each fluorescein-linked adapter was tethered to a unique tumor-specific ligand capable of binding one of the cancer cell's antigens. When coadministered with the anti-FITC CAR T cells, such a cocktail of adapters could conceivably engage all cancer cell clones in an antigenically heterogeneous tumor and lead to tumor eradication without selection for antigen-deficient resistant clones.…”

Utilizing Peptide Ligand GPCRs to Image and Treat Pancreatic Cancer

“…Evidence suggests that these are acinar cell–derived neoplastic PanIN epithelial cells, opening the potential for using NK1R-targeted imaging for detection of early lesions [ 46 ]. Tumor imaging using an NK1R-targeted fluorescent dye has been used during surgery to facilitate identification and resection of NK1R-positive lesions [ 47 , 48 ]. In PET imaging, 64 Cu-NK1R-NOTA is a promising reagent for identifying NK1R-expressing tumors [ 49 ], and NK1R-targeted cytotoxic drugs are also under development [ 50 ].…”