Heterobivalent dual-target probe for targeting GRP and Y1 receptors on tumor cells

Abstract

Receptor targeting ligands for imaging and/or therapy of cancer are limited by heterogeneity of receptor expression by tumor cells, both inter-patient and intra-patient. It is often more important for imaging agents to identify local and distant spread of disease than it is to identify a specific receptor presence. Two natural hormone peptide receptors, GRPR and Y1, are specifically interesting because expression of GRPR, Y1 or both is up-regulated in most breast cancers. We describe here the design and development of a new heterobivalent peptide ligand, truncated bombesin (t-BBN)/BVD15-DO3A, for dual-targeting of GRPR and Y1, and validation of its dual binding capability. Such a probe should be useful in imaging cells, tissues and tumors that are GRPR and/or Y1 positive and should target radioisotopes, for example, 68Ga and/or 177Lu, to more tumors cells than single GRPR or Y1 targeted probes. A GRP targeting ligand, J-G-Abz4-QWAVGHLM-NH2 (J-G-Abz4-t-BBN), and an Y1 targeting ligand, INP-K[ε-J-(α-DO3A-ε-DGa)-K]-YRLRY-NH2([ε-J-(α-DO3A-ε-DGa)-K]-BVD-15), were synthesized and coupled to produce the heterobivalent ligand, t-BBN/BVD15-DO3A. Competitive displacement binding assays using t-BBN/BVD15-DO3A against 125I-Tyr4-BBN yielded an IC50 value of 18 ± 0.7 nM for GRPR in T-47D cells, a human breast cancer cell line. A similar assay using t-BBN/BVD15-DO3A against porcine 125I-NPY showed IC50 values of 80 ± 11 nM for Y1 receptor in MCF7 cells, another human breast cancer cell line. In conclusion, it is possible to construct a single DO3A chelate containing probe that can target both GRPR and Y1 on human tumor cells.

In VitroMouse and Human Serum Stability of a Heterobivalent Dual-Target Probe That Has Strong Affinity to Gastrin-Releasing Peptide and Neuropeptide Y1 Receptors on Tumor Cells

“…A Y1 targeting ligand and a heterobivalent dual-target probe conjugated with a DO3A chelating agent, BVD15-DO3A and t-BBN/BVD15-DO3A, respectively, were synthesized, purified, and characterized by MALDI (matrixassisted laser desorption/ionization) mass as given elsewhere. 35 Purity of these materials was determined between 96% and 98% by an analytical HPLC (high-performance liquid chromatography) method. 35 Samples of fresh mouse serum collected on the day of experiment and commercial human serum purchased from MP Biomedical (Solon, OH) were used in in vitro serum stability studies.…”

“…To overcome these issues, multivalency approaches involving peptide homodimers and heterodimers have emerged recently. [29][30][31][32][33][34][35] These dimers are capable of targeting either two different domains of one receptor or two different receptors simultaneously.…”

“…Reubi recently determined that both GRPr and Y1 receptors were present in many breast cancer tissue samples and, importantly, that they were expressed in a complementary way. 3 Consequently, in a recent report 35 we described the design and development of a novel heterobivalent peptide ligand, t-BBN/BVD15-DO3A (Structure III, Fig. 1), that consists of a GRP targeting ligand J-G-Abz4-QWAVGHLM-NH 2 and a Y1 targeting ligand INP-K[e-J-(a-DO3A-e-DGa)-K]YRLRY-NH 2 .…”

Targeting Neuropeptide Receptors for Cancer Imaging and Therapy: Perspectives with Bombesin, Neurotensin, and Neuropeptide-Y Receptors

“…Heterodimeric ligands were developed for dual targeting of GRPR and NPY receptors in breast cancer (61). Arg-Gly-Asp-bombesin hybrid peptides were also developed for dual targeting of GRPR and integrin a v b 3 -aiming receptors on tumor cells and vasculature (62).…”

Bispecific radioligands targeting prostate‐specific membrane antigen and gastrin‐releasing peptide receptors on the surface of prostate cancer cells

“…28,37,39,40 Examples include bispecific ligands targeting as follows: GRPr/integrin (RGD peptides), 39,[41][42][43] PSMA/integrin, 38 PSMA/GRPr (bombesin, BN, peptides), 28,44-47 PSMA/hepsin (indole analogs), 48 and PSMA/Y1 receptors. 49 Targets like PSMA, GRPr, and integrin are well studied for imaging and endoradiotherapy applications in the preclinical and clinical level, while for hepsin and Y1 receptors, less data are available in the literature.…”