A stapled chromogranin A-derived peptide is a potent dual ligand for integrins αvβ6 and αvβ8

Combining 2D STD-NMR, computation, biochemical assays and click-chemistry, we have identified a chromogranin-A derived compound (5) that has high affinity and bi-selectivity for αvβ6 and αvβ8 integrins and is stable in microsomal preparations

Improving chemotherapeutic drug penetration in tumors by vascular targeting and barrier alteration

Drug delivery and penetration into neoplastic cells distant from tumor vessels are critical for the effectiveness of solid-tumor chemotherapy. We have found that targeted delivery to tumor vessels of picogram doses of TNF-α (TNF), a cytokine able to alter endothelial barrier function and tumor interstitial pressure, enhances the penetration of doxorubicin in tumors in murine models. Vascular targeting was achieved by coupling TNF with CNGRC, a peptide that targets the tumor neovasculature. This treatment enhanced eight- to tenfold the therapeutic efficacy of doxorubicin, with no evidence of increased toxicity. Similarly, vascular targeting enhanced the efficacy of melphalan, a different chemotherapeutic drug. Synergy with chemotherapy was observed with 3–5 ng/kg of targeted TNF (intraperitoneally), about 10(6)-fold lower than the LD(50) and 10(5)-fold lower than the dose required for nontargeted TNF. In addition, we have also found that targeted delivery of low doses of TNF to tumor vessels does not induce the release of soluble TNF receptors into the circulation. The delivery of minute amounts of TNF to tumor vessels represents a new approach for avoiding negative feedback mechanisms and preserving its ability to alter drug-penetration barriers. Vascular targeting could be a novel strategy for increasing the therapeutic index of chemotherapeutic drugs

Succinimide-Based Conjugates Improve IsoDGR Cyclopeptide Affinity to α_vβ₃ without Promoting Integrin Allosteric Activation

The isoDGR sequence is an integrin-binding motif that has been successfully employed as a tumor-vasculature-homing molecule or for the targeted delivery of drugs and diagnostic agents to tumors. In this context, we previously demonstrated that cyclopeptide <b>2</b>, the product of the conjugation of <i>c</i>(CGisoDGRG) (<b>1</b>) to 4-(<i>N</i>-maleimidomethyl)­cyclohexane-1-carboxamide, can be successfully used as a tumor-homing ligand for nanodrug delivery to neoplastic tissues. Here, combining NMR, computational, and biochemical methods, we show that the succinimide ring contained in <b>2</b> contributes to stabilizing interactions with α_vβ₃, an integrin overexpressed in the tumor vasculature. Furthermore, we demonstrate that various cyclopeptides containing the isoDGR sequence embedded in different molecular scaffolds do not induce α_vβ₃ allosteric activation and work as pure integrin antagonists. These results could be profitably exploited for the rational design of novel isoDGR-based ligands and tumor-targeting molecules with improved α_vβ₃-binding properties and devoid of adverse integrin-activating effects

Succinimide-Based Conjugates Improve IsoDGR Cyclopeptide Affinity to α_vβ₃ without Promoting Integrin Allosteric Activation

The isoDGR sequence is an integrin-binding motif that has been successfully employed as a tumor-vasculature-homing molecule or for the targeted delivery of drugs and diagnostic agents to tumors. In this context, we previously demonstrated that cyclopeptide <b>2</b>, the product of the conjugation of <i>c</i>(CGisoDGRG) (<b>1</b>) to 4-(<i>N</i>-maleimidomethyl)­cyclohexane-1-carboxamide, can be successfully used as a tumor-homing ligand for nanodrug delivery to neoplastic tissues. Here, combining NMR, computational, and biochemical methods, we show that the succinimide ring contained in <b>2</b> contributes to stabilizing interactions with α_vβ₃, an integrin overexpressed in the tumor vasculature. Furthermore, we demonstrate that various cyclopeptides containing the isoDGR sequence embedded in different molecular scaffolds do not induce α_vβ₃ allosteric activation and work as pure integrin antagonists. These results could be profitably exploited for the rational design of novel isoDGR-based ligands and tumor-targeting molecules with improved α_vβ₃-binding properties and devoid of adverse integrin-activating effects

Enhancement of Tumor Homing by Chemotherapy-Loaded Nanoparticles

Targeted delivery of anticancer drugs with nanocarriers can reduce side effects and ameliorate therapeutic efficacy. However, poorly perfused and dysfunctional tumor vessels limit the transport of the payload into solid tumors. The use of tumor-penetrating nanocarriers might enhance tumor uptake and antitumor effects. A peptide containing a tissue-penetrating (TP) consensus motif, capable of recognizing neuropilin-1, is here fused to a neuroblastoma-targeting peptide (pep) previously developed. Neuroblastoma cell lines and cells derived from both xenografts and high-risk neuroblastoma patients show overexpression of neuropilin-1. In vitro studies reveal that TP\u2013pep binds cell lines and cells derived from neuroblastoma patients more efficiently than pep. TP\u2013pep, after coupling to doxorubicin-containing stealth liposomes (TP\u2013pep\u2013SL[doxorubicin]), enhances their uptake by cells and cytotoxic effects in vitro, while increasing tumor-binding capability and homing in vivo. TP\u2013pep\u2013SL[doxorubicin] treatment enhances the Evans Blue dye accumulation in tumors but not in nontumor tissues, pointing to selective increase of vascular permeability in tumor tissues. Compared to pep\u2013SL[doxorubicin], TP\u2013pep\u2013SL[doxorubicin] shows an increased antineuroblastoma activity in three neuroblastoma animal models mimicking the growth of neuroblastoma in humans. The enhancement of drug penetration in tumors by TP\u2013pep-targeted nanoparticles may represent an innovative strategy for neuroblastoma