Researchers at Tel Aviv University say they may have developed a new way to treat and prevent melanoma, through the use of a “nano-vaccine.”

The new approach to fighting the most aggressive type of skin cancer has so far been effective in mice in preventing the development of melanoma and in treating primary tumors and metastases that result from melanoma, the researchers said in a study.

“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,” said a statement by Prof. Satchi-Fainaro, chair of the Department of Physiology and Pharmacology and head of the Laboratory for Cancer Research and Nanomedicine at TAU’s Sackler Faculty of Medicine, who led the study.

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The focus of the research, published on Monday in Nature Nanotechnology, is a nanoparticle that serves as the basis for the new vaccine.

Melanoma develops in the skin cells that produce melanin or skin pigment. The cancer accounts for only about 1% of skin tumors, but is behind a large majority of skin cancer deaths, according to the American Cancer Society. Some 7,230 people in the US are expected to die of melanoma in 2019, according to the American Cancer Society.

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

The researchers used tiny particles, about 170 nanometers in size, made up of biodegradable polymers. Within each particle, they “packed” two peptides — short chains of amino acids, which are found in melanoma cells. They then injected the nanoparticles (or “nano-vaccines”) into mice that had melanoma.

“The nanoparticles acted just like known vaccines for viral-borne diseases,” Satchi-Fainaro said. “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 immunized mice will attack melanoma cells if and when they appear in the body.”

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

In the first scenario, the vaccine was injected into healthy mice, followed by an injection of melanoma cells. “The result was that the mice did not get sick, meaning that the vaccine prevented the disease,” Satchi-Fainaro said. This means the vaccine proved to have a preventative effect, she explained.

Second, the nanoparticle vaccine was used to treat a primary melanoma tumors in mice, together with immunotherapy treatments that are already approved for use or still under development. The combination of the vaccine with the treatment “significantly delayed the progression of the disease and greatly extended the lives of all treated mice,” the statement said.

In the last scenario, the researchers tested their approach on tissues taken from human patients in which the melanoma cancer cells had spread to the brain. They found that in the human brain, where there is metastases, the two same peptides exist. This suggested that just as these two peptides can trigger an immune reaction in mice when used as a nano-vaccine, they are likely to trigger a similar reaction in the brain, indicating that the vaccine could be used to treat brain metastases in humans as well, Satchi-Fainaro said in a phone interview.

The next step for the researchers, she said in the phone interview, is to “show that we can control the growth” of the metastasized cells in order to “prolong overall survival.”

The researchers believe that their “nano-vaccine” approach could be expanded beyond melaoma.

“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,” Satchi-Fainero said.

The researchers are now setting up a company to take the development of their nano-vaccine further. It may take at least five to 10 years before a product could reach the market, if all the clinical trials go well, she said in the interview.

The team of researchers included Prof. Helena Florindo of the University of Lisbon, while on sabbatical at the TAU, and Dr. Anna Scomparin and postdoctoral fellow Dr. João Conniot, both of the TAU.

The project was funded by EuroNanoMed-II, the Israeli Health Ministry, the Portuguese Foundation for Science and Technology (FCT), the Israel Science Foundation (ISF), the European Research Council (ERC) Consolidator and Advanced Awards, the Saban Family Foundation – Melanoma Research Alliance (MRA) Team Science Award, and the Israel Cancer Research Fund (ICRF).