Summary

Introduction: New therapeutic approaches are needed for elderly or frail head and neck squamous cell carcinoma (HNSCC) patients (pts) ineligible for standard of care. NBTXR3, hafnium oxide nanoparticles injected intratumorally, may represent an option. Otherwise inert, NBTXR3 augments the radiation therapy (RT) dose within tumor cells when activated by RT, increasing tumor cell death compared to RT alone.

Objectives: The purpose of this Phase I was to evaluate safety (dose limiting toxicity; DLT) and determine the NBTXR3 recommended phase 2 dose (RP2D) in elderly or frail HNSCC pts.

Methods: Eligible pts had stage III or IV HNSCC of oral cavity or oropharynx, were aged ≥70 years or ≥65 years and unable to receive cisplatin but eligible for RT [NCT01946867]. A 3+3 dose escalation design was employed, with NBTRX3 dose levels of 5%, 10%, 15% and 22% of baseline tumor volume. Following intratumoral NBTXR3 injection, pts received IMRT (70 Gy; 35 fractions/7 weeks). Primary endpoints were RP2D and DLT. Localization of NBTXR3 and preliminary efficacy (RECIST 1.1) were also evaluated.

Results and Conclusion: Dose escalation is complete; 19 pts received NBTXR3: 3 at 5%, 3 at 10%, 5 at 15% and 8 at 22%. No NBTXR3-related DLTs or SAEs were observed. Four related AEs were reported: one AE at 15% (G1 tumor hemorrhage) and 3 AEs at 22% (G2 oral pain; G1 asthenia, G1 injection site hemorrhage). IMRT toxicity was as expected and post-injection CT scan showed NBTXR3 localized within the injected tumor. DSMB determined RP2D to be 22%. Among 13 evaluable pts at doses ≥10%, 9 had a complete response of injected tumor. Results demonstrate that NBTXR3 activated by RT is a well-tolerated therapy with encouraging anti-tumor activity. RP2D expansion is ongoing. NBTXR3 may be an option for elderly or frail pts with locally advanced HNSCC.

Summary

For patients (pts) with hepatocellular carcinoma (HCC) or liver metastasis (liver mets), stereotactic body radiation therapy (SBRT) is a well-tolerated option. Yet, the risk of injury to normal tissues limits the ability to efficiently sterilize tumor cells. Thus, hafnium oxide nanoparticles, NBXTR3, were developed, which increase the interaction of radiotherapy energy dose deposition within tumor cells when activated by an ionizing energy source like SBRT. NBTXR3 innovative approach does not engage liver function, is characterized by a single injection and fits with radiotherapy standards with no change in pts treatment protocol or equipment occupancy.

NBTXR3 is currently evaluated in this population in a phase I/II clinical trial. So far, 13 pts are enrolled. Dose levels are completed at 10% (6 pts) and 15% (4 pts) and currently enrolling at 22% (3 pts). Up to date, no early DLTs and no adverse events related to NBTXR3 were observed. In 9 evaluable pts, the investigator mRECIST assessment on target lesions resulted with the following best observed response: 3 complete responses, 3 partial responses, 1 stable disease and 2 progressive disease. In the same pts, NBTXR3 did not present leakage and did not affect liver function.

NBTXR3 activated by SBRT currently reveal an encouraging safety profile with a favorable efficacy in a vulnerable population with two different liver affections. These outcomes were the result of a complex multidisciplinary cooperation of different medical expertise from different centers.

Summary

Elderly patients (pts) with head and neck squamous cell carcinoma (HNSCC) represent 25% of the affected population. They are not always eligible to the same treatment of younger pts, thus require new therapies. NBTXR3, injectable hafnium oxide nanoparticles activated by radiotherapy (RT), was developed to increase the local deposit of energy within the tumor. It is currently evaluated in a phase I trial for locally advanced HNSCC in elderly and frail patients.

Current results indicate a safe and well tolerated profile for NBTXR3 even at the highest doses highlighting an encouraging perspective in the elderly. This population stress a medical need of which few HNSCC trials answer.

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.