Access Pharmaceuticals initiates Cobalamin technology program for targeted delivery of siRNA therapies

Feb 5 2010

ACCESS PHARMACEUTICALS, INC. (OTC Bulletin Board: ACCP) announced today that it initiated an internal pre-licensing program to confirm the utility of its proprietary Cobalamin (vitamin B12) platform technology for targeted delivery of siRNA therapies. The program is considered important because, despite the widely publicized potential of RNA therapy, researchers up to now have been stymied in their efforts to design a pharmaceutical product that efficiently transports siRNA therapeutics into the cells they are designed to inhibit or kill.

Access has multiple programs ongoing around use of its Cobalamin technology to facilitate oral absorption of pharmaceuticals, including previously announced collaborations with potential pharma and biotech partners. To date, its successful Cobalamin product development program has focused on the oral delivery of insulin and human growth hormone, two peptides that currently can only be given by injection.  Because these two molecules share some of the same physical characteristics as RNA's active components, Access believes its Cobalamin technology could effectively deliver RNA therapy in an oral tablet instead of by injection.

But a more compelling feature of the Cobalamin technology may be its ability to overcome the cellular transport obstacles that have held back fuller development of RNA therapy. The large size and high negative charge of RNA molecules prevents their absorption by target cells.  Using the 'Trojan Horse' principle, the Cobalamin nanoparticle technology can encapsulate small fragments of RNA (siRNA) and utilize the Colalamin's vitamin B12 uptake mechanism to transport them into target cells, allowing release of the active drug to initiate the therapeutic effect.  Cobalamin's vitamin B12 uptake mechanism offers the potential for targeted delivery of siRNA because most human cells have a requirement for vitamin B12.  This 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.  

"Access scientists and collaborators have so far demonstrated in preclinical models that Cobalamin formulations are effective in achieving good oral drug delivery of charged peptides such as insulin and human growth hormone," commented David P. Nowotnik, Senior Vice President, Research and Development. "These successes with molecules which share some of the same physical characteristics as siRNA would indicate that we should now be able to generate effective formulations of Cobalamin nanoparticles for delivery of siRNA. We know already from previous work that we can make cancer drugs more effective using the Cobalamin approach, and so we have a sound scientific basis for the future development of Cobalamin RNAi therapeutics."

Cobalamin is Access' proprietary technology based upon the use of vitamin B12 for targeted delivery of drugs to disease sites and for oral drug delivery of drugs that otherwise have poor oral bioavailability. Access has focused its Cobalamin product development program on the oral delivery of insulin and human growth hormone, two peptides that currently can only be given by injection. Since presenting promising results at a major conference in mid-2008, Access has made substantial improvements to the formulation technology. A new Cobalamin-coated insulin-containing nanoparticle formulation delivered orally provided a pharmacological response (lowering of blood glucose levels in an animal model of diabetes) equivalent to greater than 80% of that achieved by insulin delivered subcutaneously. This represents a substantial oral bioavailability, indicating that this formulation has potential for clinical development and ultimate commercialization. Adaptation of this technology has provided a Cobalamin human growth hormone formulation that has demonstrated good efficacy, represented by more than 25% improvement in weight gain, when given orally in an established animal model. Access continues to move both products towards clinical development, and plans to submit an additional patent application to protect the improvements to the technology.