Scientists test a topical treatment strategy against skin cancer
Researchers at the University of São Paulo (USP) in Brazil are testing mice in a technique that associates a low-intensity electrical current with a formula containing nanoencapsulated chemotherapeutic drugs for the treatment of skin cancer.
“One of the challenges in this type of topical treatment is to get the drug through the stratum corneum, which is the most superficial layer of the skin, composed basically of dead cells, which constitutes an important barrier of the tissue against the entrance of microorganisms, but also makes the penetration of drugs difficult, “said Renata Fonseca Vianna Lopez, a professor at the Faculty of Pharmaceutical Sciences of Ribeirão Preto (FCFRP-USP).
The application of a low intensity unidirectional current is one of the ways to get certain chemicals through the skin by pushing them to the circulation through the application of an electric field. This technique is known as iontophoresis.
However, in the case of skin cancer, the intent is not for the drug to pass through the tissue and into the blood, but to concentrate on the area below the corneal layer that requires treatment. This is the reason why, in the work coordinated by Fonseca Vianna Lopez, it was decided to put the chemotherapeutic in nanoparticles. This work is carried out within the framework of a Thematic Project that has the support of FAPESP.
The researchers induced the formation of a squamous cell carcinoma-type tumor – one of the most common types of skin cancer – in the animals by subcutaneous injection of human tumor cells overexpressing the EGFR gene (epidermal growth factor receptor, for its acronym in English). The presence of this protein, according to Fonseca Vianna Lopez, returns to the more aggressive tumor.
The treatment was performed with a formula containing the chemotherapeutic 5-fluorouracil encapsulated in a nanoparticle (liposome) functionalized with an anti-EGFR antibody. Malignant cells are able to capture a greater amount of the drug encapsulated in these liposomes.
The group that was given the formula associated with iontophoresis exhibited a significantly greater tumor reduction in relation to the group to which it was injected.
“In addition to reducing the size of the tumor, the topical treatment made it less aggressive. We believe that this method associated with iontophoresis allows the drug to spread throughout the tumor area, while in the subcutaneous application it is concentrated in one only place, “said Fonseca Vianna Lopez.