News of Note—Merck's virus-based drug shows promise in bladder cancer; CRISPR halts hearing loss in mice

Merck’s common cold virus shrinks bladder cancer in small human study
Last year, Merck laid out $394 million to acquire Viralytics, an Australian company that’s testing a cancer-killing virus, Cavatak, along with Merck’s PD-1 inhibitor Keytruda in early trials. Now researchers at University of Surrey and Royal Surrey County Hospital in the United Kingdom say they have early evidence from a small human trial that Cavatak—an RNA virus that causes the common cold—may improve the treatment of non-muscle invasive bladder cancer. In the study, the patients received Cavatak by catheter in their bladders one week prior to undergoing surgery to remove their tumors. Urine samples taken from patients showed that the virus first infected cancerous cells, replicating and causing the cells to die, then it traveled to infect distant cancer cells in the bladder. In the study, published in the journal Clinical Cancer Research, the team reported that Cavatak boosted cancer cell death in all of the 15 patients who received the treatment, and that in one patient, no trace of the cancer was found during surgery. (Release)

Fine-tuned CRISPR preserves hearing in mouse models of genetic deafness

A defective copy of the gene Tmc1 causes a form of inherited, progressive hearing loss that renders its victims deaf by their mid-20s. A team of researchers at Harvard Medical School and Boston Children’s Hospital used a modified form of CRISPR-Cas9 gene editing to disable the defective copy of Tmc1 in mice, they reported in the journal Nature Medicine. The technology was able to spot a single incorrect DNA letter among 3 billion letters in the mouse genome, the researchers explained. Instead of using a guide RNA to target DNA for cutting, the CRISPR system developed by the research team uses a modified Cas9 enzyme to boost accuracy. They believe the technology will be able to be applied to several disorders marked by defective copies of single genes. (Release)

New insight into cancer resistance in bats could boost oncology research
Researchers at Duke-NUS Medical School in Singapore have discovered a protein that’s abundant in bats and that may be key in rendering the creatures resistant to cancer. The protein, called ABCB1, acts as a pump in the surface of cells, clearing out toxic substances. ABCB1 is not only more prevalent in bat tissues than it is in humans, it’s also more widely distributed, the researchers said. They found that exposing cells from bats to toxic drugs caused less DNA damage and cell death than it did in human cells. When they blocked the protein in bat cells, it caused toxic chemicals to build up, leading to DNA damage and death. In people, prolonged chemotherapy raises levels of ABCB1, which could cause cells to discard the drug, leading to chemoresistance. The researchers believe their findings, published in the journal Nature Communications, could be used to develop cancer therapies targeting ABCB1. (Release)