Scientists have developed a unique nanoparticle vaccine that prevented the development of multiple forms of cancer in mice, reports a study published in Cell Reports Medicine on Thursday.

Eighty percent of mice that received the novel vaccine and were subsequently exposed to cancerous cells did not develop tumors and survived to the end of the 250-day long experiment. In contrast, all of the mice that received different vaccine formulations, or remained unvaccinated, developed tumors and none survived longer than 35 days.

It’s too early to know if this breakthrough will ever be applicable to human cancer prevention or treatment, but the successful demonstration in mice is a promising result for the team’s so-called “super-adjuvant” vaccine. This approach uses nanoparticles made of fatty molecules to deliver two distinct “adjuvants,” which are substances in vaccines that enhance an immune response.

“The results that we have are super exciting, and we're really looking forward to pushing forward to the next steps,” said Griffin Kane, a postdoctoral research associate at the University of Massachusetts Amherst and first author on the paper, in a call with 404 Media. “But I think that the translation of these types of therapies from preclinical mouse models to the clinic is a very humbling experience for a lot of people and teams.”

“It’s these highlights that make it worth coming to work,” added Prabhani Atukorale, assistant professor of biomedical engineering in the Riccio College of Engineering at UMass Amherst and corresponding author on the paper, in the same call. “But I agree that the translation of these findings is key. We are not satisfied with simply publishing a paper. We want to get these into patients, and it is a humbling process because there are significant gaps.”
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Scientists have been working on nanoparticle-based drug designs for decades, and the field has experienced rapid progress in recent years alongside advances in nanotechnology and drug delivery pathways. Nanoparticles provide a stable platform for carrying vaccine components to key targets, increasing the efficiency of delivery to specific sites in the body and uptake by the immune system.

Atukorale’s team previously published a study on a similar vaccine that shrank and cleared tumors from mice. In their new study, the researchers adapted the nanoparticle design to achieve prophylactic protection from melanoma, pancreatic, and triple-negative breast cancer in mice, with support from the Institute for Applied Life Sciences at UMass Amherst, UMass Chan Medical School, and the National Institutes of Health.

Vaccines consist of two main components: antigens, which are substances that trigger an immune response, and adjuvants, which enhance the immune response. Like other cancer vaccines, the nanoparticle treatment delivers antigens that activate white blood cells in the immune system to help fight off specific types of tumors.

What’s new in this study is that the nanoparticles accommodated two distinct adjuvants that target different immune pathways known as STING (stimulator of interferon genes) and TLR4 (Toll-like receptor 4), which further boosts the immune response to introduced cancer cells.

Adjuvants often require very different drug delivery systems, but the nanoparticles, which are about 30 to 60 nanometers across, are big enough to house different adjuvants in their unique environments, while remaining small enough to enter lymph nodes where they can activate key immune cells.

“The big picture is that we need better adjuvants for our vaccines,” Atukorale said. “We think that we can build them using nanoparticles. This is an example in a tumor.”

One of the most exciting surprises from the study turned out to be the prolonged protection against the spread of cancer provided by the nanoparticle vaccine. The vaccinated mice that did not develop tumors during their first exposure to melanoma cells were then later injected with new metastatic cancer cells, and their immune systems fought those off too, preventing the development and spread of the tumors.

“There's long-term robust memory immunity,” said Kane.

Moreover, while the team focused on certain cancers in their experiment, the nanoparticle platform could deliver a range of specialized antigen-adjuvant combinations to target different types of tumors.

“We think that this is one of the true strengths of these strategies,” said Atukorale. “They will have much broader reach than many of the cancer-specific treatments out there.”

That said, Kane and Atukorale cautioned that their team’s work is still in early stages—and, of course, focused on mice and not people. They also noted that only a handful of cancer vaccines have been clinically approved out of thousands in development. While the new study represents an intriguing step forward, the dream of wide-ranging prophylactic cancer vaccines is many years away, assuming it can materialize at all.

“A lot of very elegant technologies have come out of labs and have not fully succeeded in patients,” Kane said. “We believe that we're building this technology towards something that would improve on what current cancer vaccines are able to deliver.”