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February 01, 2009 (Vol. 29, No. 3)

CytImmune Banks on Gold Nanoparticles

Clinical-Stage Firm Delivers TNF-α to Tumors with Proprietary Colloidal Gold System

  • Click Image To Enlarge +
    Design of CytImmune Sciences’ colloidal gold-based cancer nanomedicine Aurimune™ (CYT-6091): Both TNF-a and thiolated polyethylene glycol (PEG-Thiol) are independently bound to the surface of 27 nm colloidal gold particles.

    CytImmune Sciences, a clinical-stage biopharmaceutical company based in Rockville, MD, is attempting to use nanotechnology to change the way we treat cancer, according to cofounder, president, and CEO Lawrence Tamarkin, Ph.D. “Our technology is designed to treat cancer medically first and then surgically intervene, thus reducing hospital stays and costs and improving the quality of life of the cancer patient.”

    When Dr. Tamarkin founded the company in 1988 along with Giulio F. Paciotti, Ph.D., currently vp of research and development, they intended to set up a diagnostic assay company. In working with colloidal gold particles to develop antibodies, they discovered that the gold particles were safe to use in drug delivery. 

    Colloidal gold had been used since the 1930s to temporarily relieve joint inflammation associated with rheumatoid arthritis. CytImmune observed that animals injected with cytokines exhibited strong toxicological responses, whereas, animals receiving injections of cytokines bound to colloidal gold did not. This observation led to the conclusion that colloidal gold may be a universal, clinically safe, commercially sound drug/gene delivery system.

    A 1999 grant from the National Institute of Standards and Technology enabled the company to begin its work. The idea of binding colloidal gold particles to tumor necrosis factor alpha (TNF-α) to target tumors directly and limit the exposure of healthy tissues and organs to this cytokine came in the mid-1990s.

    What evolved was a company with a core focus on the discovery, development, and commercialization of multifunctional, tumor-targeted therapies. Based on an R&D strategy that harnesses the unique properties of gold nanoparticles, CytImmune is developing a pipeline of proprietary drug candidates that bind potent anticancer agents—whose toxicity profiles currently prevent or severely limit their clinical use—to its patented colloidal gold tumor-targeting nanotechnology.

    The company has more than 60 issued and pending patents for its colloidal gold nanotechnology and 11 issued and pending patents for its monoclonal antibody (mAb) technology in the U.S., EU, Japan, and Canada.

    TNF-α was discovered in 1975, and Genentech made recombinant TNF-α in 1985. Clinical testing during the next decade showed that there was no efficacy for TNF-α at a safe dose. While regarded as an effective anticancer agent, when administered systemically, TNF-α attacks endothelial cells, causing hypotension that may lead to organ failure, Dr. Tamarkin explains.

    Between 1992 and 2004, isolated limb perfusion (ILP) studies in Europe demonstrated that TNF-α could be administered safely if the blood supply were isolated. Using mouse cancer models, CytImmune discovered that attaching TNF-α to gold nanoparticles is a safe and effective targeted drug delivery formulation, Dr. Tamarkin explains.

    The mechanism underlying CytImmune’s tumor-targeted delivery of TNF-α is attributable to the size and composition of the nanoparticles, regardless of the tumor type, Dr. Tamarkin notes. The therapeutic payload travels safely through the bloodstream, avoiding immediate immune detection and arriving at the targeted disease site.

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