Truncated Autoinducing Peptide Conjugates Selectively Recognize and Kill Staphylococcus aureus.

The accessory gene regulator (agr) of Staphylococcus aureus coordinates various pathogenic events and is recognized as a promising therapeutic target for virulence control. S. aureus utilizes autoinducing peptides (AIPs), cyclic-peptide signaling molecules, to mediate the agr system. Despite the high potency of synthetic AIP analogues in agr inhibition, the potential of AIP molecules as a delivery vehicle for antibacterial agents remains unexplored. Herein, we report that truncated AIP scaffolds can be fused with fluorophore and cytotoxic photosensitizer molecules without compromising their high agr inhibitory activity, binding affinity to the receptor AgrC, or cell specificity. Strikingly, a photosensitizer-AIP conjugate exhibited 16-fold greater efficacy in a S. aureus cell-killing assay than a nontargeting analogue. These findings highlight the potential of truncated AIP conjugates as useful chemical tools for in-depth biological studies and as effective anti-S. aureus agents.

Cyclic DGR-peptidomimetic containing a bicyclic reverse turn inducer as a selective alpha(v)beta (5) integrin ligand.

3-Aza-6,8-dioxabicyclo[3.2.1]octane-based amino acids as reverse turn inducers have been introduced into cyclic peptidomimetics containing the RGD or DGR retro-sequence, in order to achieve a stereochemical scanning of the binding capability of the resulting molecules towards alpha(v)beta(3) and alpha(v)beta(5) integrins, resulting in retro-inverso DGR peptides as micromolar ligands. A comparative analysis between the conformational preferences of 4 and of its isomer 3, having the opposite RGD sequence, was reported with respect to the binding activity, giving insight into the factors affecting the preferential binding of 4 to the alpha(v)beta(5) integrin.

A phase 1 study of systemic ADH-1 in combination with melphalan via isolated limb infusion in patients with locally advanced in-transit malignant melanoma.

BACKGROUND: Isolated limb infusion with melphalan is a well-tolerated treatment for patients with in-transit extremity melanoma with an approximately 30% complete response (CR) rate. ADH-1 is a cyclic pentapeptide that disrupts N-cadherin adhesion complexes and when given systemically in a preclinical model of regional melphalan therapy demonstrated synergistic antitumor activity. A phase 1 dose escalation study to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of systemic ADH-1 in combination with melphalan via isolated limb infusion in patients with in-transit extremity melanoma was performed. METHODS: Dose escalation cohorts of 3 patients each received 1000, 2000, and 4000 mg (10 patients) of ADH-1 administered intravenously on Days 1 and 8 with standard dose melphalan via isolated limb infusion on Day 1. N-cadherin immunohistochemistry staining and quantitative polymerase chain reaction analysis were performed on pretreatment tumor. Response was defined at 3 months using modified Response Evaluation Criteria in Solid Tumors. RESULTS: Sixteen patients have been treated with no observed dose-limiting toxicities. Common treatment-related grade 1 or 2 toxicities included skin/dermatologic (n=14) and pain (n=12). Grade 3 toxicities included shortness of breath (n=1), hypertension (n=1), serologic toxicities (n=4), and 1 grade 4 creatine phosphokinase elevation. In-field responses included 8 CRs, 2 partial responses, 1 stable disease, and 5 progressive diseases. Pharmacokinetic analysis demonstrated increasing ADH-1 concentrations at each dose and minimal variability in melphalan drug levels. CONCLUSIONS: Systemic ADH-1 at a dose of 4000 mg on Days 1 and 8 in combination with melphalan via isolated limb infusion is a well-tolerated, novel targeted therapy approach to regionally advanced melanoma. The number of CRs exceeded expectations, suggesting that targeting N-cadherin may be a new strategy for overcoming melanoma chemoresistance.

The long-acting vasoactive intestinal polypeptide agonist RO 25-1553 is highly selective of the VIP2 receptor subclass.

RO 25-1553 is a synthetic VIP analogue that induced a long-lasting relaxation of tracheal and bronchial smooth muscles as well as a reduction of edema and eosinophilic mobilization during pulmonary anaphylaxis. In the present study, we tested in vitro the capacity of RO 25-1553 to occupy the different VIP/PACAP receptor subclasses and to stimulate adenylate cyclase activity. The cellular models tested expressed one single receptor subtype: Chinese hamster ovary (CHO) cells transfected with the rat recombinant PACAP I, rat VIP1, and human VIP2 receptors; SUP T1 cells expressing the human VIP2 and HCT 15 and LoVo cells expressing the human VIP1 receptor. RO 25-1553 was threefold more potent than VIP on the human VIP2 receptor, 100- and 600-fold less potent than VIP on the rat and human VIP1 receptors, respectively, and 10-fold less potent than VIP and 3000-fold less potent than PACAP on the PACAP I receptor. RO 25-1553 was a full agonist on the VIP2, the PACAP I, and the rat recombinant VIP1 receptor but a partial agonist only on the human VIP1 receptor. Thus, RO 25-1553 is a highly selective agonist ligand for the VIP2 receptor subclass.