An early-stage study has found a strain of the common cold virus can effectively target and destroy bladder cancer cells. This phase 1 human trial suggests the virus directly induces tumor cell death, and if verified by larger trials could be used in conjunction with other novel immunotherapy treatments.

An oncolytic virus is a class of virus known to target and kill cancer cells in one of two ways, either by directly hunting and eliminating tumor cells, or by helping the immune system better home in on a cancer by lighting up a cancer cell. Ongoing oncolytic research has revealed the zika virus attacking brain cancers, and the herpes virus attacking skin cancers.

Non-muscle invasive bladder cancer (NMIBC) is the most common type of bladder cancer and it is challenging to treat. Current treatments can involve a variety of either surgery, chemotherapy or immunotherapy, and still result in high rates of recurrence.

"Non-muscle invasive bladder cancer is a highly prevalent illness that requires an intrusive and often lengthy treatment plan," explains Hardev Pandha, principle investigator on the new study. "Current treatment is ineffective and toxic in a proportion of patients and there is an urgent need for new therapies."

This new research describes the results of a phase 1 trial using a strain of the common cold virus called coxsackievirus (CVA21), as an oncolytic agent targeting bladder cancer. The trial recruited 15 patients with NMIBC and administered CVA21 directly into the bladder via a catheter. One week after the treatment the patients underwent surgery to remove their bladder tumors, allowing the researchers to evaluate how well the virus had infiltrated the cancer cells.

The results were promising, with all patients displaying evidence the virus has effectively infiltrated the bladder cancer cells. Tumor cell death was seen to be triggered by the virus, and increases in inflammatory cytokines were noted, suggesting the virus also seemed to stimulate the body's immune system to better target and attack the cancer cells.

"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," says Pandha. "Notably, no significant side effects were observed in any patient."

Being a phase 1 human trial the primary goal was to evaluate safety and dosage, and the results were positive on this front, with no toxicities or adverse effects reported. The next step will be to expand these trials and explore whether this new treatment can be used in combination with new immunotherapy treatments.

This isn't the first research into using the common cold virus as an oncolytic agent. CVA21 in particular is looking promising as a treatment for melanoma and prostate cancer, with several human trials currently underway evaluating its efficacy when used in conjunction with other immunotherapy treatments.

The new research was published in the journal Clinical Cancer Research.