Tumor targeting by a carbohydrate ligand-mimicking peptide

Tumor vasculature-targeted 10B delivery by an Annexin A1-binding peptide boosts effects of boron neutron capture therapy

Background

p-Boronophenylalanine (¹⁰BPA) is a powerful ¹⁰B drug used in current clinical trials of BNCT. For BNCT to be successful, a high (500 mg/kg) dose of ¹⁰BPA must be administered over a few hours. Here, we report BNCT efficacy after rapid, ultralow-dose administration of either tumor vasculature-specific annexin A1-targeting IFLLWQR (IF7)-conjugated ¹⁰BPA or borocaptate sodium (¹⁰BSH).

Methods

(1) IF7 conjugates of either ¹⁰B drugs intravenously injected into MBT2 bladder tumor-bearing mice and biodistribution of ¹⁰B in tumors and normal organs analyzed by prompt gamma-ray analysis. (2) Therapeutic effect of IF7-¹⁰B drug-mediated BNCT was assessed by either MBT2 bladder tumor bearing C3H/He mice and YTS-1 tumor bearing nude mice.

Results

Intravenous injection of IF7C conjugates of either ¹⁰B drugs into MBT2 bladder tumor-bearing mice promoted rapid ¹⁰B accumulation in tumor and suppressed tumor growth. Moreover, multiple treatments at ultralow (10–20 mg/kg) doses of IF7-¹⁰B drug-mediated BNCT significantly suppressed tumor growth in a mouse model of human YTS-1 bladder cancer, with increased Anxa1 expression in tumors and infiltration by CD8-positive lymphocytes.

Conclusions

We conclude that IF7 serves as an efficient ¹⁰B delivery vehicle by targeting tumor tissues via the tumor vasculature and could serve as a relevant vehicle for BNCT drugs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07760-x.

Overcoming the blood-brain barrier by Annexin A1-binding peptide to target brain tumours

Background

Annexin A1 is expressed specifically on the tumour vasculature surface. Intravenously injected IF7 targets tumour vasculature via annexin A1. We tested the hypothesis that IF7 overcomes the blood–brain barrier and that the intravenously injected IF7C(RR)-SN38 eradicates brain tumours in the mouse.

Methods

(1) A dual-tumour model was generated by inoculating luciferase-expressing melanoma B16 cell line, B16-Luc, into the brain and under the skin of syngeneic C57BL/6 mice. IF7C(RR)-SN38 was injected intravenously daily at 7.0 μmoles/kg and growth of tumours was assessed by chemiluminescence using an IVIS imager. A similar dual-tumour model was generated with the C6-Luc line in immunocompromised SCID mice. (2) IF7C(RR)-SN38 formulated with 10% Solutol HS15 was injected intravenously daily at 2.5 μmoles/kg into two brain tumour mouse models: B16-Luc cells in C57BL/6 mice, and C6-Luc cells in nude mice.

Results

(1) Daily IF7C(RR)-SN38 injection suppressed tumour growth regardless of cell lines or mouse strains. (2) Daily injection of Solutol-formulated IF7C(RR)-SN38 led into complete disappearance of B16-Luc brain tumour in C57BL/6 mice, whereas this did not occur in C6-Luc in nude mice.

Conclusions

IF7C(RR)-SN38 crosses the blood–brain barrier and suppresses growth of brain tumours in mouse models. Solutol HS15-formulated IF7C(RR)-SN38 may have promoted an antitumour immune response.

IF7-Conjugated Nanoparticles Target Annexin 1 of Tumor Vasculature against P-gp Mediated Multidrug Resistance

Multidrug resistance is the main cause of clinical chemotherapeutic failure. Antiangiogenic cancer therapy with nanomedicine that allows the targeted delivery of antiangiogenic agents to tumor endothelial cells may contribute to innovative strategies for treating multidrug-resistant cancers. In this study, we developed a new nanodrug delivery system (nano-DDS), with improved antiangiogenic efficacy against multidrug resistant human breast cancer MCF-7/ADR cells. Here, the IF7 ligand was a peptide designed to bind the annexin 1 (Anxa 1), a highly specific marker of the tumor vasculature surface, with high affinity and specificity. IF7-conjugated Anxa 1-targeting nanoparticles containing paclitaxel (IF7-PTX-NP) allowed controlled drug release and displayed favorable prolonged circulation in vivo. IF7-PTX-NP was significantly internalized by human umbilical vein endothelial cells (HUVEC) through the IF7-Anxa 1 interaction, and this facilitated uptake enhanced the expected antiangiogenic activity of inhibiting HUVEC proliferation, migration, and tube formation in a Matrigel plug relative to those of Taxol and PTX-NP. As IF7-PTX-NP targeted the tumor vessels, more nanoparticles accumulated in MCF-7/ADR tumors, and more importantly, induced significant apoptosis of the tumor vascular endothelial cells and necrosis of the tumor tissues. Low dose paclitaxel (1 mg/kg) formulated in IF7-PTX-NP showed significant anticancer efficacy, delaying the growth of MCF-7/ADR tumors. The same efficacy was only obtained with an 8-fold dose of paclitaxel (8 mg/kg) as Taxol plus XR9576, a potent P-gp inhibitor. The anticancer efficacy of IF7-PTX-NP was strongly associated with the improved antiangiogenic effect, evident as a dramatic reduction in the tumor microvessel density and pronounced increase in apoptotic tumor cells, with no obvious toxicity to the mice. This nano-DDS, which targets the tumor neovasculature, offers a promising strategy for the treatment of multidrug-resistant cancer.