Access Pharmaceuticals Furthers Progress on its Cobalamin-Mediated Targeted Drug Delivery Platform for siRNA

(Nanowerk News) Access Pharmaceuticals, Inc., a biopharmaceutical company leveraging its proprietary drug-delivery platforms to develop treatments in areas of oncology, cancer supportive care and diabetes, announced today that it has made significant progress with its proprietary Cobalamin-targeted drug-delivery program for siRNA therapies. As a result of the continued advancements made with its Cobalamin program, Access rebranded the targeted-drug delivery technology as CobaCyte™; and submitted additional patent applications for its improved CobaCyte formulations, including siRNA compositions.
Over the past months, Access' CobaCyte siRNA application has shown significant promise. In an in vitro siRNA transfection dose-response study, Access' CobaCyte nanoparticle carriers loaded with an apoptosis-inducing siRNA molecule showed transfection activity in hard-to-transfect cell lines with potentially better toxicity profiles compared to other reagents. Further studies including in vivo gene-knockdown studies are planned. Additionally, Access has initiated a program whereby proprietary formulations of currently marketed chemotherapies will be developed and tested to assess CobaCyte's ability to enhance drug pharmacokinetics and pharmacodynamics.
"We're excited about the early progress and results seen in our CobaCyte-targeted drug-delivery activities, especially in the area of siRNA," stated Jeffrey B. Davis, President and CEO of Access Pharmaceuticals. He continued, "The new patent filings and the branding of the CobaCyte name will help enhance and facilitate our corporate partnering activity in this area."
"Access and its collaborators have demonstrated that our CobaCyte carrier nanoparticles can get siRNA molecules in cells, and that we can impact transfection efficiency by varying the loading of vitamin B-12, our principle targeting agent," commented David P. Nowotnik, Senior Vice President, Research and Development. He continued, "Based on our collective work with current and previous formulations using the CobaCyte approach, we believe we have the right scientific basis in place for the future development of CobaCyte RNAi therapeutics."
RNAi is typically initiated by the introduction of small fragments of RNA, termed siRNA, into cells at disease sites. Due to their large size and high negative charge, siRNA fragments are not able to cross cell membranes. Therefore, to develop effective RNAi therapeutics, a delivery system must be developed that can transport the siRNA into cells, and release undamaged siRNA into target cell cytoplasm. The CobaCyte technology is particularly well-suited for this purpose. Most human cells have a requirement for vitamin B12 which is served by cell surface receptors which facilitate absorption of this vitamin. In many diseases, the demand for vitamin B12 is increased, with a corresponding upregulation of the receptor. Using the 'Trojan Horse' principle, the CobaCyte nanoparticle technology can utilize the vitamin B12 uptake mechanism to transport siRNA into cells whereupon native siRNA can be released for incorporation in messenger RNA (mRNA) to initiate the beneficial therapeutic effect. In this way, CobaCyte offers the potential for targeted delivery of siRNA. The fact that Access' vitamin B12 technology also facilitates oral drug delivery indicates that it may be possible for this technology to provide effective siRNA treatments by oral drug delivery.
For additional information on CobaCyte siRNA please click on the following link to view Dr. Nowotnik's recent invited presentation at the Novel Nanodelivery of siRNA and miRNA Symposium, hosted by the California NanoSystems Institute at UCLA:
About Access
Access Pharmaceuticals, Inc. is an emerging biopharmaceutical company that develops and commercializes proprietary products for the treatment and supportive care of cancer patients. Access' products include MuGard™ (, for the management of patients with mucositis, ProLindac™, currently in Phase II clinical testing of patients with ovarian cancer, and Thiarabine, a new generation nucleoside analog which has demonstrated both pre-clinical and clinical activity in certain cancers.
The company also has other advanced drug delivery technologies including CobaCyte™-mediated targeted delivery and Cobalamin-oral drug delivery, its proprietary nanopolymer delivery technology based on the natural vitamin B12 uptake mechanism. For additional information on Access Pharmaceuticals, please visit our website at
Source: Access Pharmaceuticals (press release)
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