The following article features coverage from the Connective Tissue Oncology Society 2021 virtual meeting. Click here to read more of Cancer Therapy Advisor’s conference coverage.

Treatment of locally advanced soft tissue sarcoma (LA-STS) with the radio-enhancer NBTXR3 plus radiotherapy (RT) did not negatively impact quality of life or long-term morbidity, according to results of the phase 2/3 ACT.IN.SARC trial presented at the Connective Tissue Oncology Society (CTOS) 2021 Annual Meeting.

The ACT.IN.SARC trial ( Identifier: NCT02379845) previously met its primary endpoint of pathologic complete response rate among patients with LA-STS of the extremity and trunk. The present analysis was of the long-term safety data from this trial.

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The trial randomly assigned 180 patients to receive RT with or without NBTXR3 prior to surgery. The long-term safety analysis included toxicities, limb function, and quality of life.

The rate of post-treatment adverse events (AEs) of any grade was higher in the RT-only arm, at 57.8%, compared with 51.7% in the NBTXR3 arm. During the entire study, 12.4% of patients experienced a severe AE due to NBTXR3, whereas the severe AE rate due to RT was 11.2% when it was combined with NBTXR3 and 13.3% when used alone.

Postsurgical wound complications and the median duration of hospital stay were similar across the arms.

There was no significant difference between arms in quality of life measured by the Toronto Extremity Salvage Score, Musculo Skeletal Tumor Rating Score, Euro QoL-5 Dimensions, and Reintegration to Normal Living Index.

Planning target volume and clinical target volume were equivalent in both arms, which suggests superior efficacy due to increased energy deposit by NBTXR3, said Sylvie Bonvalot, MD, PhD, of PSL Research University in Paris, who presented this research at the meeting.

Dr Bonvalot concluded that this long-term safety profile, together with the efficacy data of NBTXR3, reinforces its good benefit-risk ratio in LA-STS.

Disclosures: This research was supported by Nanoviotix, and Dr Bonvalot declared affiliations with Nanoviotix .

Read more of Cancer Therapy Advisor’s coverage of CTOS 2021 by visiting the conference page.


Bonvalot S, Rutkowski PL, Thariat J, et al. Long-term evaluation of NBTXR3, a novel radioenhancer, plus radiotherapy in patients with locally advanced soft tissue carcinoma treated in the phase II/III ACT.IN.SARC trial. Presented at CTOS 2021; November 10-13, 2021. Abstract 42.