A combination of implanted immune system cells and external-beam radiation therapy (EBRT) safely induced antitumor immune responses in more than half of patients with high-risk soft-tissue sarcomas who had participated in a small trial.

Sarcomas are relatively rare forms of cancer, with about 10,000 new cases diagnosed in the United States each year, noted study coauthor Dmitry Gabrilovich, MD, PhD, senior member of the H. Lee Moffitt Cancer Center & Research Institute in Tampa, Florida. Approximately half of all patients with high-grade soft-tissue sarcomas develop distant metastasis.

“Unfortunately, conventional therapy for large, high-grade tumors is frequently systematically ineffective, making this a very deadly problem,” explained Gabrilovich in a statement issued by the Moffitt Center to announce the study results, which were published in International Journal of Radiation Oncology, Biology, Physics (2012;82[1]:924-932).

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Gabrilovich and team combined administration of dendritic cells and EBRT in 17 patients with large (larger than 5 cm), high-grade soft-tissue sarcomas. Dendritic cells process antigen material and present it to other immune cells, making administration of dendritic cells a promising method for producing an immune response. Because previous research had shown preoperative radiotherapy and surgery to be an effective treatment for high-risk soft-tissue sarcomas, the investigators hypothesized that dendritic-cell implants combined with EBRT could each enhance the effectiveness of the other. 

Although none of the patients had experienced tumor-specific immune responses before undergoing dendritic cell/EBRT treatment, 9 patients (52.9%) developed such responses following treatment. The responses lasted from 11 to 42 weeks, with 12 of the 17 patients (70.6%) remaining progression-free after 1 year.

Gabrilovich and colleagues described the combination therapy as well-tolerated, and concluded that because a strong antitumor response was produced with no adverse side effects, larger trials involving more patients are warranted.