Urine-powered nanobots shrink bladder cancer tumors in mice by 90%

Researchers have developed a novel way to treat bladder cancer. Powered by urea, a waste substance found in urine, nanobots propel themselves to and penetrate the tumor to deliver their onboard radioactive treatment. After one dose, tumors in mouse models shrank by almost 90%, opening the door to a promising alternative treatment for this cancer, which tends to recur.

Current treatments for non-muscle-invasive bladder cancer, which represents approximately 75% of cases, include the administration of immunotherapeutic and/or chemotherapy drugs into the bladder following tumor resection. While these treatments show good survival rates, they have limited effectiveness, as evidenced by five-year recurrence rates of 30% to 70%, requiring the patient to undergo regular and costly bladder surveillance procedures (cystoscopy) and, potentially, further treatment.

In an effort to improve the effectiveness of bladder cancer treatment, researchers from the Institute for Research in Biomedicine (IRB) Barcelona, in collaboration with the Institute for Bioengineering of Catalonia (IBEC), CIC biomaGUNE, and the Autonomous University of Barcelona (UAB), developed self-propelled nanobots that accumulate at the tumor site to deliver cancer-fighting treatment directly.

Taking advantage of the bladder’s internal environment, the researchers’ tiny robots are powered by urine, specifically the urea in urine. The surface of a nanosized porous silica sphere is modified to carry components with specific functions. One is urease, an enzyme that catalyzes the hydrolysis of the urea present in urine to ammonia and carbon dioxide, causing the nanobot to propel itself. Another key surface component is radioactive iodine, iodine-131, a radioisotope commonly used for the localized treatment of tumors.

After injecting their urease-powered nanobots into the bladders of mouse models of bladder cancer, the researchers used positron emission tomography (PET) scans to show that the bots accumulated at the tumor site. Examination under microscopy, which researchers from IRB Barcelona had developed specially, showed that the bots penetrated the tumor. The nanobots’ administration of iodine-131 at the tumor site resulted in a reduction in tumor volume of nearly 90%.

“With a single dose, we observed a 90% decrease in tumor volume,” said Samuel Sánchez, one of the study’s corresponding authors. “This is significantly more efficient than current treatments, given that patients with this type of tumor typically have between six and 14 hospital appointments. This therapeutic approach would increase efficiency by reducing the length of hospitalizations and the cost of treatment.”

The novel treatment paves the way for more effective treatments for bladder cancer. The next step for the researchers, which they’re already working on, is determining whether the tumors recur after treatment.

The study was published in the journal Nature Nanotechnology.

Source: IRB Barcelona