Rhabdomyosarcoma (RMS) is a cancer that begins in soft tissues, which are the tissues that connect, support, and surround organs and other structures in the body. It is the most common type of soft tissue cancer in children and adolescents. Unfortunately, outcomes for patients whose disease has spread throughout the body have not improved in decades. Despite months of intensive chemotherapy and major surgery, many patients with advanced RMS still die from their disease.

The human immune system has the ability to detect and eliminate abnormal cells, including cancer cells. However, cancer cells often develop ways to weaken or evade the immune system, allowing tumors to grow unchecked. Immunotherapy is a type of treatment that helps the immune system recognize and attack cancer cells. Because immunotherapy uses the body’s own defenses, it can target cancer cells while largely sparing healthy tissues. In many cancers, this approach has shown remarkable success.

Unfortunately, current immunotherapies have not worked well in sarcomas such as RMS, and the reasons for this are not well understood. Through our research, we discovered that RMS tumors sometimes contain small clusters of immune cells that resemble tiny lymph nodes within the tumor itself. These structures, called tertiary lymphoid structures, may play an important role in helping the immune system recognize and attack cancer cells.