Summary

Purpose: This phase I study aimed to determine the recommended dose (RD), safety profile, and feasibility of a procedure combining intratumoral injection of hafnium oxide nanoparticles (NBTXR3; a radioenhancer) and external beam radiotherapy (EBRT) for preoperative treatment of adults with locally advanced soft tissue sarcoma (STS).

Experimental Design: Patients had a preoperative indication of EBRT for STS of the extremity or trunk. Baseline tumor volume (TV) was calculated by MRI. NBTXR3 was injected percutaneously into tumors at 53.3 g/L. Dose escalation was based on four levels equivalent to 2.5%, 5%, 10%, and 20% of baseline TV. NBTXR3 was visualized in the tumor 24 hours postinjection, and EBRT was initiated (50 Gy over 5 weeks). Surgery was performed 6 to 8 weeks after EBRT completion.

Results: Twenty-two patients completed NBTXR3 injection, EBRT, and surgery and were followed for a median 22 months (range, 6–40). At NBTXR3 20% of TV, two dose-limiting toxicities occurred: injection-site pain and postoperative scar necrosis. The RD was defined as 10%. No leakage of NBTXR3 into surrounding tissues occurred; intratumor NBTXR3 levels were maintained during radiotherapy. At the RD, median tumor shrinkage was 40% (range 71% shrinkage, 22%increase);median percentage of residual viable tumor cells was 26% (range, 10%–90%). Patients receiving 20% of TV demonstrated pathologic complete responses. Seven grade 3 adverse events occurred, which were reversible.

Conclusion: A single intratumoral injection of NBTXR3 at 10% of TV with preoperative EBRT was technically feasible with manageable toxicity; clinical activity was observed. Clin Cancer Res; 1–10. 2016 AACR.

Summary

Aim: There is considerable interest in approaches that could improve the therapeutic window of radiotherapy. In this study, hafnium oxide nanoparticles were designed that concentrate in tumor cells to achieve intracellular highenergy dose deposit. Materials & methods: Conventional methods were used, implemented in different ways, to explore interactions of these high-atomicnumber nanoparticles and ionizing radiation with biological systems.

Results: Using the Monte Carlo simulation, these nanoparticles, when exposed to highenergy photons, were shown to demonstrate an approximately ninefold radiation dose enhancement compared with water. Importantly, the nanoparticles show satisfactory dispersion and persistence within the tumor and they form clusters in the cytoplasm of cancer cells. Marked antitumor activity is demonstrated in human cancer models. Safety is similar in treated and control animals as demonstrated by a broad program of toxicology evaluation.

Conclusion: These findings, supported by good tolerance, provide the basis for developing this new type of nanoparticle as a promising anticancer approach in human patients.

Summary

Nanotechnology offers revolutionary strategies to improve healthcare. Adequate nanomaterial characterization constitutes the basis to establish relevant programs of nanoparticle/biological systems cross talk evaluation. Also, the surrounding conditions significantly impact on the state of the nanoparticles in terms of their collective behavior: dispersion, aggregation, and stability in gas or liquid.

The “principle of designing” specific products is the paradigm of the nanomedecine. It is really new and it represents an essential point since creating innovative products should be supported by a previous risk evaluation based on the nanoscale chemistry. Furthermore, size does matter. Thus, both, size and chemistry of nanoparticles are probably the fundamental parameters from which all others depend on, and ultimately nanomaterial surface. And surfaces are the key players when considering safety.