Researchers at the University of Surrey and Royal Surrey County Hospital are looking at a strain of cold virus called coxsackievirus (CVA21) as a possible means of treating non-muscle invasive bladder cancer (NMIBC). The researchers used CVA21 to infect cancer cells and trick the body's immune system into attacking them.
"Coxsackievirus could help revolutionise treatment for this type of cancer," said Dr. Hardev Pandha, professor of medical oncology at the University of Surrey.
Cancers in the bladder usually don't have immune cells, which poses a problem – it prevents a patient's own immune system from fighting off the tumor as it grows. Places in the body without immune cells like the bladder are known as "cold" areas immunologically. With this in mind, the researchers came up with the idea to use CVA21 to create immunological "heat" and draw immune cells toward the bladder.
To test their idea, the researchers inserted CVA21 into the bladders of 15 patients via catheter one week prior to a pre-scheduled surgery to remove the tumors. Upon examining tissue samples from the patients post-surgery, the researchers discovered that the virus was highly selective, targeting only the cancerous cells and leaving healthy cells alone.
Analysis of the tissue samples showed that virus infected the cancerous cells and then replicated itself, causing the malignant cells to rupture and die. In addition, urine samples taken from the patients on alternate days detected "shedding" from the virus. This "shedding" showed that once the virus had killed a tumor, it continued to attack more cancerous cells in the bladder.
Following the treatments, the researchers identified virus cell death in most of the patients' tumors. In fact, doctors even found no trace of cancer in one patient during surgery.
NMIBC is usually quite tricky and painful to treat as the current methods of doing so are quite problematic. One of the methods of treating the cancer, an invasive procedure called transurethral resection, is supposed to remove all lesions. However, this procedure has a high recurrence rate ranging from 50 to 70 percent. It also has a high tumor progression rate of between 10 and 20 percent over a period of two to five years.
The other common method, immunotherapy with a live bacterium called Bacille Calmette-Guerin, is found to have serious side effects on one-third of NMIBC patients. Another one-third do not respond to the treatment at all. (Related: Smoking Linked to Bladder Cancer.)
"Non-muscle invasive bladder cancer is a highly prevalent illness that requires an intrusive and often lengthy treatment plan," stated Pandha. "Current treatment is ineffective and toxic in a proportion of patients and there is an urgent need for new therapies."
And coxsackievirus may be key to the development of a new treatment for this type of cancer.
"Reduction of tumor burden and increased cancer cell death was observed in all patients and removed all trace of the disease in one patient following just one week of treatment, showing its potential effectiveness. Notably, no significant side effects were observed in any patient," Pandha added.
Dr. Nicola Annels, a research fellow at the University of Surrey, noted that while viruses have traditionally been associated with sickness, in the right situation, they can improve people's health by destroying cancer cells.
"Oncolytic viruses such as the coxsackievirus could transform the way we treat cancer and could signal a move away from more established treatments such as chemotherapy," Annels said.