Microneedle patch delivers localized cancer immunotherapy to melanoma

Researchers developed a patch that uses microneedles to deliver anti-PD-1 antibodies locally to the skin tumour.

In the immune system, T cells are supposed to identify and kill cancer cells. To do their job, T cells use specialized receptors to differentiate healthy cells from cancer cells. But cancer cells can trick T cells. One way cancer cells do this is by expressing a protein ligand that binds to a receptor on the T cells to prevent the T cell from recognizing and attacking the cancer cell.

Recently, cancer immunotherapy research has focused on using “anti-PD-1” (or programmed cell death) antibodies to prevent cancer cells from tricking T cells.

“However, this poses several challenges,” says Chao Wang, co-lead author of a paper on the microneedle research and a postdoctoral researcher in the joint biomedical engineering program at NC State and UNC-Chapel Hill. “First, the anti-PD-1 antibodies are usually injected into the bloodstream, so they cannot target the tumour site effectively. Second, the overdose of antibodies can cause side effects such as an autoimmune disorder.”

To address these challenges, the researchers developed a patch that uses microneedles to deliver anti-PD-1 antibodies locally to the skin tumour. The microneedles are made from hyaluronic acid, a biocompatible material.

The anti-PD-1 antibodies are embedded in nanoparticles, along with glucose oxidase – an enzyme that produces acid when it comes into contact with glucose. These nanoparticles are then loaded into microneedles, which are arrayed on the surface of a patch.

When the patch is applied to a melanoma, blood enters the microneedles. The glucose in the blood makes the glucose oxidase produce acid, which slowly breaks down the nanoparticles. As the nanoparticles degrade, the anti-PD-1 antibodies are released into the tumour.

“This technique creates a steady, sustained release of antibodies directly into the tumour site; it is an efficient approach with enhanced retention of anti-PD-1 antibodies in the tumour micro-environment,” says Zhen Gu, an assistant professor in the biomedical engineering program and senior author of the paper.

The researchers tested the technique against melanoma in a mouse model. The microneedle patch loaded with anti-PD-1 nanoparticles was compared to treatment by injecting anti-PD-1 antibodies directly into the bloodstream and to injecting anti-PD-1 nanoparticles directly into the tumour.

“After 40 days, 40% of the mice who were treated using the microneedle patch survived and had no detectable remaining melanoma – compared to a 0% survival rate for the control groups,” says Yanqi Ye, a PhD student in Gu’s lab and co-lead author of the paper.

The researchers also created a drug cocktail, consisting of anti-PD-1 antibodies and another antibody called anti-CTLA-4, which also helps T cells attack the cancer cells.

“Using a combination of anti-PD-1 and anti-CTLA-4 in the microneedle patch, 70% of the mice survived and had no detectable melanoma after 40 days,” Wang says.

“Because of the sustained and localized release manner, mediated by microneedles, we are able to achieve desirable therapeutic effects with a relatively low dosage, which reduces the risk of auto-immune disorders,” Gu says.

“We’re excited about this technique, and are seeking funding to pursue further studies and potential clinical translation,” Gu adds.

The paper, “Enhanced Cancer Immunotherapy by Microneedle Patch-Assisted Delivery of Anti-PD-1 Antibody,” is published in the journal Nano Letters. The paper was co-authored by Gabrielle Hochu, an undergraduate in the biomedical engineering program, and Hasan Sadeghifa, a postdoctoral researcher at NC State. The work was supported by NC TraCS, NIH’s Clinical and Translational Science Awards at UNC-Chapel Hill, under grant number 1UL1TR001111.