ANTIBODIES: MedImmune, Ixsys in Four MAb Pact
MedImmune and Ixsys have formed an alliance to develop four monoclonal antibodies. One product, a humanized antibody known as Vitaxin is in phase one trials as a cancer treatment that works by inhibiting angiogenesis. Vitaxin was developed and optimized by Ixsys using a proprietary technology called directed evolution. Under terms of the agreement, Ixsys will use its directed evolution protein engineering technology to optimize three additional antibodies identified by MedImmune. MedImmune will be responsible for clinical development, manufacturing and commercialization of any resulting products. MedImmune will also make a $6.4 million equity investment in Ixsys, will fund certain research performed by Ixsys, and will make future milestone and royalty payments on sales of any products that result from the collaboration. Potential value of the collaboration to Ixys, exclusive of royalties, could be $50 million. The lead product, Vitaxin, inhibits angiogenesis by binding to an integrin, called alpha-v beta-3 (a.k.a. the vitronectin receptor) that is found specifically on newly sprouting blood vessels. Binding of the integrin by Vitaxin appears to stimulate programmed cell death, stopping the growth of the vessels. This inhibition of new blood vessel has been shown to block the growth and spread of solid tumors in animal models. A recent phase one clinical trial has been performed involving 14 patients with incurable malignant cancer. Vitaxin was found to be generally safe and well-tolerated. Of 14 patients, 8 experienced stabilization of their disease and there was a reduction in tumor size in 1 patient. A phase one/two imaging study has been completed at the University of Alabama and phase two study involving leiomyosarcoma patients is in progress at the M.D. Andersen Center. Additional trials are planned using Vitaxin to treat patients with glioblastoma, breast, or colon cancer. Rheumatoid arthritis may be an additional indication. Vitaxin was developed from a murine antibody known as LM609 produced by David A. Cheresh, of the Scripps Research Institute, the discoverer of alpha-v beta-3 integrin. The murine antibody was humanized by Ixsys and the binding affinity was increased using the directed evolution technology that allows the efficient creation and screening of new protein variations. “Our work with human tumor tissue in animal models at the Scripps Research Institute has clearly demonstrated the ability of Vitaxin to inhibit solid tumor growth and metastases,” says Cheresh. “We have also shown the critical role of alpha-v beta-3 integrin in ocular neovascular diseases, such as macular degeneration and proliferative diabetic retinopathy. The potential for Vitaxin to inhibit this angiogenic pathway has far reaching implications in clinical medicine.”
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