Immunotherapy and Radiation Provide Good Tumor Response in Sarcoma Patients

Dmitry Gabrilovich, MD, PhD

A combination of immunotherapy and fractionated external-beam radiation therapy (EBRT) provided tumor-specific immune responses that lasted from 11 to 42 weeks in more than 50% of patients with soft-tissue sarcoma in a recent study in the International Journal of Radiation Oncology Biology Physics (2012;82(2):924-932. Epub March 11, 2011).

The study found that adding immunotherapy in the form of dendritic cells to EBRT resulted in a potent anti-tumor response without serious adverse effects. Twelve of the 17 patients experienced progression-free survival lasting more than a year.

“Sarcomas are relatively rare forms of cancer with about 10,000 new cases in the US annually,” said Dmitry Gabrilovich, MD, PhD, of the Moffitt Cancer Center in Tampa, Florida, where the study took place.

“Many studies have shown that preoperative radiotherapy and surgery is effective in treating many soft tissue sarcomas with high-risk features,” Gabrilovich said. “We designed our study to investigate the effect of combining the administration of dendritic cells and EBRT for patients with soft tissue, highrisk sarcomas.”

Giving dendritic cells is a promising approach because they process antigen material and present it to other immune cells. The researchers hypothesized that the dendritic cells would help process tumor antigens released by the EBRT treatment.

“The combination treatment resulted in dramatic increases in immune T cells in the tumors,” said Gabrilovich. “The presence of T cells in the tumors positively correlated with the development of tumor-specific immune responses.”

No patient had significant tumor-specific immune responses before the combined therapy. After the combination treatment, tumor-specific responses were observed in 52.9% of trial patients.