Rhabdomyosarcoma, a cancer made up of cells that normally develop into skeletal muscles, is the most common soft tissue cancer in children. If it is detected early and localized in certain areas, rhabdomyosarcoma is usually curable with traditional therapies like surgery, radiation and chemotherapy. However, these treatments are fraught with side effects, especially for children.

A recent study points to a new treatment strategy that takes advantage of the body's own immune response.

Over the past decade, immunotherapy has become an important part of treating some cancers effectively and with fewer side effects than traditional therapies. One immunotherapeutic approach is oncolytic virotherapy, in which a virus is used to target cancer cells specifically. Oncolytic viruses infect and kill malignant, but not normal, cells.

In the new study, researchers from Nationwide Children's Hospital used a combination of immunotherapies in a mouse model of rhabdomyosarcoma.

In addition to oncolytic virotherapy, the team also blocked the signaling of programmed cell death protein (PD)-1, which mediates the suppression of T-cells.

The researchers say the combination therapy is so effective because it marshals more of the T-cells that attack infections and tumors to the site of the cancer without increasing the counterbalancing, regulatory T-cells that suppress immune attacks.

Both oncolytic virotherapy and PD-1 blockade are FDA-approved for treating cancer; this new study provides preclinical data to support combining them in pediatric cancer patients.