| DERMATOLOGY | OPINION mouse studies, there was no evidence
of unwanted effects, and no accumulation of the nanoparticles in other parts of the body. The researchers claim their results
indicate that siRNA-gold nanoparticle conjugates could be used in personalised, topically-delivered gene therapy of cutaneous tumours, such as melanoma or squamous cell carcinoma, as well as in inflammatory skin disorders such as psoriasis and in dominant negative genetic skin disorders. They could even conceivably be used to treat wrinkles and other signs of ageing.
Safety issues Intellectual property rights to the SNA technology used in the study are owned by AuraSense Therapeutics LLC, a company headquartered in Evanston and in which three of the paperÕs authors have a financial interest (one of the authors, Dr Chad A Mirkin, is a founder of the company, while a second, Dr David A Giljohann, is the companyÕs chief operating officer). As well as skin disorders, the company is looking to apply the technology to the management of other types of cancer, respiratory ailments, and transplants. However, while these findings are
encouraging for both the dermatology and cosmetics sectors, they really only represent a proof-of-principle, and much work still needs to be done before the research can be exploited in a commercial product. In particular, despite the reported absence of adverse effects, concerns have been expressed about the use of nanoparticles, particularly as the technology is still in its infancy. Nanoparticles are already used in a number of cosmetic and toiletry products, such as sunscreens and lipsticks, but disquiet about their safety persists. In fact, in April this year the US FDA
issued draft guidance on the safety of nanomaterials in cosmetic products. It stated that, because the use of nanomaterials may affect the quality, safety, effectiveness and/or public health impact of a product, data needs and testing methods should be evaluated in light of the unique properties and function of the nanomaterials used in cosmetic products. As far as safety assessment is concerned, the FDA recommended that particular attention be applied to
the physicochemical characteristics of the nanomaterials, the presence of any impurities, the potential for agglomeration of the nanomaterials, toxicological data on ingredients and impurities, and clinical studies to test the product in human volunteers.
Development of anti-cancer drugs AuraSense Therapeutics is just one of a number of companies studying ways of improving the delivery of anti-cancer drugs in patients with skin cancer. Berg Pharma, LLC, a Boston-based pharmaceutical company, focuses on how alterations in metabolism relate to disease onset. It has exploited the Warburg effect, the phenomenon by which cancer cells preferentially use glucose for molecular sustainability of the oncogenic phenotype. The company has developed a technology platform, which it refers to as the Berg Biosystems Interrogative Biology platform, and which it says has enabled it to elucidate the key factors involved in the control of the metabolic differences between healthy cells and cancer cells. To exploit this research, Berg has
developed a topical cream formulation of ubidecarenone (coenzyme Q10), which it claims has the ability to normalise mitochondrial oxidative phosphorylation and cellular metabolic networks to create an anti-cancer effect. Berg refers to such compounds as Ôepimetabolic shiftersÕ . Its ubidecarenone product, codenamed API 31510, has demonstrated safety and efficacy in two clinical trials, one in patients with basal cell carcinoma, and the other in patients with
squamous cell carcinoma. Further trials are planned. Improving the delivery of drugs to the skin is also the focus of an Australian company, Phosphagenics Ltd, which is based in Melbourne. The companyÕs platform technology is the Targeted Penetration Matrix (TPM) system, use of which is claimed to reduce dose-related side-effects, prevent first-pass hepatic metabolism (the phenomenon whereby a proportion of an orally administered drug is broken down by the liver before it even reaches the site where it is needed), and improve patient compliance. Other advantages claimed for the TPM
system is that it is easy to manufacture, non-invasive, user-friendly and non-irritant. It has been found to be suitable for delivering a range of molecules, even quite large ones such as insulin. In the skin disorders area, Phosphagenics is working with an unnamed dermatology company to develop a new product that combines the TPM technology with a specific anti-acne drug. That product is still at the preclinical stage of development, but Phosphagenics is also developing an improved TPM formulation of the anti-acne drug tretinoin in its own right.
Gel formations Another drug that has an established place in the treatment of acne is benzoyl peroxide, which not only has an antibacterial effect, but also increases the turnover of skin cells. Therefore, the application of the compound to unaffected skin is undesirable, and a variety of formulations are available that aim to restrict delivery of the compound to the affected skin. New formulations with improved delivery continue to be developed. GlaxoSmithKline, for example, is developing a 3% gel formulation of benzoyl peroxide. Gels have become quite a popular vehicle for delivering drugs to the skin, and a number of other companies are also working in this area. For instance, a US
company, Oxygen Biotherapeutics, Inc., is developing Wundecyte, a topical gel-like formulation of Oxycyte (an experimental
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