Microparticles amp up the effect of breast cancer vaccines

Cancer vaccines have had a long and troubled history in the clinic, often proving safe but relatively ineffective in killing cancer cells. Now a team at Houston Methodist says that a tiny porous silicon microparticle (PSM) could prove a key tool in amping up the efficacy of cancer vaccines.

The investigators loaded the particles with the HER2 antigen in their preclinical study, and found that the test triggered a strong immune response against cancer cells that overexpressed the antigen. The microparticles worked in in vivo and in vitro studies even when they weren't loaded.

"We have shown for the first time that a microparticle can serve as a carrier for sustained release and processing of tumor antigens," said principal investigator Haifa Shen. "But just as importantly, we learned the microparticles themselves appear to be enough to stimulate a type I interferon response, and were even transferred from one antigen-presenting cell to another to maintain a long-lasting antigen-releasing effect."

Investigator Haifa Shen

Shen knows that the breast cancer vaccines that have been tested against HER2-positive cases have flopped in the clinic. But he thinks this new method has real potential, and not just for breast cancer.

PSMs "persistently challenge the antigen-presenting cells to activate the T cells," he said. "And the PSMs modify the tumor microenvironment so that the cytotoxic T cells maintain their activity."

One other trend that may help give this approach a tryout in human studies: Cancer vaccines are increasingly being used in combination with other therapies as investigators set out to widen the response rate and improve patients' chances of prolonged survival with a more durable design.

- here's the release

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