Researchers have developed a novel nano-vaccine for melanoma, the most aggressive type of skin cancer.

Their innovative approach has so far proven effective in preventing the development of melanoma in mouse models and in treating primary tumours and metastases that result from melanoma.

The focus of the research is on a nanoparticle that serves as the basis for the new vaccine. 

The results have been published in the journal Nature Nanotechnology.

Melanoma develops in the skin cells that produce melanin or skin pigment.

"The war against cancer in general, and melanoma in particular, has advanced over the years through a variety of treatment modalities, such as chemotherapy, radiation therapy and immunotherapy; but the vaccine approach, which has proven so effective against various viral diseases, has not materialised yet against cancer," said Prof Satchi-Fainaro, who led the study. "In our study, we have shown for the first time that it is possible to produce an effective nano-vaccine against melanoma and to sensitise the immune system to immunotherapies."

The researchers harnessed tiny particles, about 170 nanometers in size, made of a biodegradable polymer.

Within each particle, they "packed" two peptides - short chains of amino acids, which are expressed in melanoma cells.

They then injected the nanoparticles (or "nano-vaccines") into a mouse model bearing melanoma.

"The nanoparticles acted just like known vaccines for viral-borne diseases," Prof Satchi-Fainaro explained. "They stimulated the immune system of the mice, and the immune cells learned to identify and attack cells containing the two peptides - that is, the melanoma cells. This meant that, from now on, the immune system of the immunised mice will attack melanoma cells if and when they appear in the body."

The researchers then examined the effectiveness of the vaccine under three different conditions.

First, the vaccine proved to have prophylactic effects.

The vaccine was injected into healthy mice, and an injection of melanoma cells followed.

"The result was that the mice did not get sick, meaning that the vaccine prevented the disease," said Prof Satchi-Fainaro.

Second, the nanoparticle was used to treat a primary tumour.

A combination of the innovative vaccine and immunotherapy treatments was tested on melanoma model mice.

The synergistic treatment significantly delayed the progression of the disease and greatly extended the lives of all treated mice.

Finally, the researchers validated their approach on tissues taken from patients with melanoma brain metastases.

This suggested that the nano-vaccine can be used to treat brain metastases as well.

Mouse models with late-stage melanoma brain metastases had already been established following excision of the primary melanoma lesion, mimicking the clinical setting. 

"Our research opens the door to a completely new approach - the vaccine approach - for effective treatment of melanoma, even in the most advanced stages of the disease," concluded Prof Satchi-Fainaro. "We believe that our platform may also be suitable for other types of cancer and that our work is a solid foundation for the development of other cancer nano-vaccines."

Source: American Friends of Tel Aviv University