Sprayable Gel Could Help The Body Fight Off Cancer After Surgery

The first step in many cancer treatments is to surgically remove the tumorous tissue, however this often isn't enough in itself. As long as a few cells of cancer remain the tumors often grow back, but an innovative new spray gel designed to be administered onto a cancerous site during surgery may help prevent the tumors recurring.

Led by a team of scientists from UCLA, the researchers developed a novel gel designed to help the body's immune system better target, and kill, cancer cells that remain after surgery. The gel is loaded with nanoparticles made up of calcium carbonate, designed to slowly dissolve in human tissue. The nanoparticles are filled with antibodies that inhibit a specific protein the cancer cells use to hide from our immune system. CD47 is a protein important in a range of different cellular processes across the human body. It is often euphemistically referred to as the "don't-eat-me" signal, helping our immune system avoid attacking things it shouldn't.

Many people who are diagnosed with cancer will undergo some type of surgery to treat their disease, said researchers from the University of California, Los Angeles (UCLA) in the US. Almost 95 per cent of people with early-diagnosed breast cancer will require surgery and it is often the first line of treatment for people with brain tumours, according to the study published in the journal Nature Nanotechnology.

However, despite improvements in surgical techniques over the past decade, the cancer often comes back after the procedure. The researchers tested the biodegradable spray gel in mice that had advanced melanoma tumours surgically removed. They found that the gel reduced the growth of the tumour cells that remained after surgery, which helped prevent recurrences of the cancer. After receiving the treatment, 50 per cent of the mice survived for at least 60 days without their tumours regrowing. The spray not only inhibited the recurrence of tumours from the area on the body where it was removed, but also controlled the development of tumours in other parts of the body, said Zhen Gu, a professor at UCLA.

The substance will have to go through further testing and approvals before it could be used in humans, Gu said. However, the scientists envision the gel being applied to the tumour resection site by surgeons immediately after the tumour is removed during surgery. "This sprayable gel shows promise against one of the greatest obstacles in curing cancer," Gu said.

"One of the trademarks of cancers is that it spreads. In fact, around 90 per cent of people with cancerous tumours end up dying because of tumour recurrence or metastasis," he said. The researchers loaded nanoparticles with an antibody specifically targeted to block CD47, a protein that cancer cells release as a "don't-eat-me" signal. By blocking CD47, the antibody enables the immune system to find and ultimately destroy the cancer cells. The nanoparticles are made of calcium carbonate, a substance that is the main component of egg shells and is often found in rocks.

"We also learned that the gel could activate T cells in the immune system to get them to work together as another line of attack against lingering cancer cells," said Qian Chen, a postdoctoral researcher in Gu's lab. Once the solution is sprayed on the surgical site, it quickly forms a gel embedded with the nanoparticles. The gel helps stop at the surgical site and promotes would healing; the nanoparticles gradually dissolve and release the anti-CD47 antibodies into the body.

PTI