Si les médicaments anti-angiogéniques actuels ont tous le même but (se lier au VEGF afin d’empecher la liaison à ses récepteurs), Ophthotech a dans son pipeline trois molécules qui s’attaquent à d’autres cibles :
- Suite à un accord de licence avec Biogen Idec et PDL BioPharma, ils développent le volociximab (M200) en ophtalmologie :
Volociximab is an investigational monoclonal antibody targeting α5β1 integrin, a key protein involved in the formation of blood vessels, a process known as angiogenesis. […] “α5β1 integrin is a critical survival factor for proliferating endothelial cells involved in angiogenesis,†said Samir Patel, MD, president and CEO of Ophthotech. « The preclinical studies to date provide very strong support for developing volociximab for ophthalmic indications. It represents a potential breakthrough for the treatment of AMD.â€
Source : OphthalmologyWeb
- Un aptamer anti-PDGF (E10030) entre en phase I, afin d’étudier sa tolérance en combinaison avec un anti-VEGF :
Platelet-derived growth factors (PDGFs) and their receptors are critical targets in anti-angiogenic therapy. PDGF plays a significant role in angiogenesis and has been implicated in ocular neovascularization. The activities of PDGF and VEGF in the initiation of angiogenesis and mediation of blood vessel growth and behavior are independent of each other, suggesting that concurrent inhibition could lead to superior efficacy in treating neovascularization.
Platelet-derived growth factor B (PDGF-B) is implicated in vascular stability and function through its role in activating the recruitment of mural cells (pericytes) by endothelial cells to envelop the developing vasculature. Pericyte recruitment is part of the maturation process in blood vessel development and pericytes act as support cells for mature blood vessels. Once the mural cell population is well established, the effectiveness of anti-VEGF agents is greatly reduced. It is possible that disruption and stripping of mural cell recruitment by an anti-PDGF agent could potentiate the efficacy of an anti-VEGF attack by causing neovascular regression. Therefore, combination therapy in wet AMD with anti-VEGF and anti-PDGF agents could represent breakthrough therapy.
E10030, an aptamer-based compound directed against PDGF-B, is being developed for the potential treatment of wet AMD. E10030 is a pegylated aptamer containing 32 monomeric units (32-mer) arranged as a linear sequence of three oligonucleotide segments connected by non-nucleotide hexaethylene glycol spacers. The aptamer terminates in a hexylamino linker to which two 20-kilodalton monomethoxy polyethylene glycol units are covalently attached via the two amino groups on a lysine residue.
Pharmacology studies indicate that E10030 binds to PDGF-B with high specificity and affinity and inhibits the functions of PDGF-B both in vitro and in vivo. In pre-clinical studies, E10030 demonstrated the potential to regress neovascularization when used in combination with a VEGF-A inhibitor. In experiments involving models of ocular vascularization [1], concurrent inhibition of PDGF-B and VEGF-A signaling was superior to inhibition of the VEGF-A pathway alone. The combined treatment was able to induce the regression of existing vessels, compared to inhibition of VEGF-A alone. Findings from a corneal neovascularization model demonstrated that pericytes were stripped from newly growing vessels, but not from existing limbal vessels. This evidence suggests that combined administration of an anti-PDGF-B agent with an anti-VEGF agent may result in regression of abnormal blood vessels in neovascular AMD while preserving the normal vascular architecture. Therefore, combination therapy with a regimen incorporating an anti-PDGF agent with an anti-VEGF agent holds great promise for enhanced efficacy in wet AMD.
Source : OSN
- En parcourant leur site internet, on trouve aussi que la voie du complément n’est pas oubliée, avec un aptamer anti-C5 (ARC1905) :
Evidence for complement-mediated inflammation in AMD is further reinforced by genetic linkage and association studies which suggest that approximately 50 to 75% of AMD cases have polymorphism in complement regulatory proteins compared to age-matched controls. […]
Anti-C5 aptamer ARC1905 is a potent and specific inhibitor of complement activation. ARC1905 is a pegylated RNA aptamer. ARC1905 inhibits C5, a central component of the complement cascade, which plays multiple roles in innate immunity and inflammatory diseases. Inhibition of this key step in the complement cascade at the level of C5 prevents the formation of key terminal fragments (C5a and C5b-9) regardless of which pathway (alternate, classical or lectin) induced their generation. The C5a fragment is an important inflammatory activator inducing vascular permeability, recruitment and activation of phagocytes. C5b-9 is involved in the formation of membrane attack complex (MAC: C5b-9) which initiates cells lysis. By inhibiting these C5-mediated inflammatory and MAC activities, therapeutic benefit may be achieved in both dry as well as wet AMD.
