Microneedles patch into skin cancer

Researchers have designed a patch full of microscopic needles that inject therapeutic nanoparticles loaded with a promising immunotherapy directly into melanomas (Nano Lett. 2016, DOI: 10.1021/acs.nanolett.5b05030).

The nanoparticle formulation of the drug, an antibody known as anti-PD1, suppressed tumors more effectively in mice compared with conventional intravenous injections, reports the research team from North Carolina State University and the University of North Carolina, Chapel Hill.

Anti-PD1 inhibits the melanoma’s ability to avoid the body’s immune system. Ligands on melanoma cells bind to programmed cell death protein 1, or PD1, on the surface of T cells, effectively short-circuiting immune responses. If anti-PD1 binds to PD1 first, however, it disables the cancer’s defense.

But anti-PD1 can stimulate attacks against healthy cells as well, possibly ­leading to autoimmune disorders, including type 1 diabetes, says team leader Zhen Gu.

The team’s microneedle patch localizes the therapeutic to tissue affected by the melanoma, and the nanoparticle formulation allows for a sustained release of the drug, he explains. In the particles, anti-PD1 is encased in a matrix of modified dextran. The matrix also encapsulates glucose oxidase enzymes, which convert blood glucose into gluconic acid. The resulting acid degrades the modified dextran particles, releasing the anti-PD1 continuously over several days.