Search

6051 Background: The non-surgical standard of care (SOC) for the treatment of locally advanced head and neck squamous cell carcinoma (LA HNSCC) patients is concurrent chemoradiation with high dose cisplatin or cetuximab in case of contra-indication to cisplatin. However elderly patients, and those with poor performance status, comorbidities, and/or intolerance, may not benefit from these SOC treatments and represent a high unmet need. New approaches are thus needed to improve clinical outcomes without adding toxicity. NBTXR3, a novel radioenhancer, composed of functionalized hafnium oxide nanoparticles, is injected once intratumorally and activated by radiotherapy (RT).NBTXR3 increases the RT energy deposit inside tumor cells and subsequently increases tumor cell death compared to RT alone, while sparing healthy tissues. We present here the results of the dose expansion part of the phase I study evaluating NBTXR3 plus intensity modulated radiation therapy (IMRT) in this population. Methods: Patients with stage III-IVA or T3/T4 (AJCC/UICC TNM staging system 8th ed.) HNSCC of the oropharynx or oral cavity, ineligible to cisplatin or cetuximab and amenable for RT, received a single intratumoral injection of NBTXR3 and IMRT (70 Gy in 35 fractions /7 weeks). A classical 3 + 3 dose escalation design has tested four doses of NBTXR3, equivalent to 5, 10, 15, and 22% of baseline theoretical tumor volume. The RP2D established as 22% of baseline tumor volume is further tested in the dose expansion part. The primary endpoints of the dose expansion part are objective response rate (ORR) and complete response rate (CRR) of the primary tumor, by imaging according to RECIST 1.1. Safety is also evaluated. Results: As of August 13, 2020, 43 patients have been treated in the phase I dose expansion part. The median age was 70.7 years old (range: 50.7- 89.9), 70% of patients had cardiac disorder risk, 44% had gastrointestinal disorder risk and 44% metabolic and nutrition disorder risk. The median tumor volume was 42.8 mL (range: 1.3 - 222.3). At a median time of 7.8 months after NBTXR3 injection, the ORR of the primary lesion was 83.9% and the CRR 67.7% in the evaluable population for efficacy (N = 31). Three patients (7%) experienced at least one serious adverse event (AE) related to the injection procedure and/or NBTXR3 which represented less than 1% of all reported AEs. RT-related toxicity was as expected with IMRT. Three deaths due to AEs related to RT and other causes were reported. The recruitment is ongoing and updated efficacy and safety results will be presented. Conclusions: NBTXR3 intratumoral administration followed by IMRT may represent an option in elderly patients or patients with multiple comorbidities with LA-HNSCC who have limited therapeutic options. NBTXR3 activated by RT showed promising anti-tumor efficacy, supporting further evaluation in a phase III randomized trial. Clinical trial information: NCT01946867.

6573 Background: The standard of care non-surgical approach for locally advanced head and neck squamous cell carcinoma (LA HNSCC) patients (pts) is concurrent chemoradiation with high dose cisplatin or cetuximab in case of contra-indication. Older age is a contra-indication to cisplatin, and cetuximab might not improve survival in older pts. It is therefore urgently needed to develop new treatment options for elderly pts with LA HNSCC. NBTXR3 are hafnium oxide nanoparticles that can enhance the efficacy of radiotherapy (RT) by increasing locally the deposited dose. In this phase I clinical trial we aimed to evaluate the feasibility and safety of NBTXR3 administered as intratumoral (IT) injection prior to RT in LA HNSCC elderly pts. Methods: Pts with stage III-IV LA HNSCC of the oropharynx or oral cavity ineligible for platinum-based chemoradiation received a single IT injection of NBTXR3 into a selected primary tumor and intensity modulated RT (IMRT; 70 Gy/35 fractions/7 weeks) [NCT01946867]. A 3+3 dose escalation design, tested NBTXR3 dose levels equivalent to 5, 10, 15, and 22% of baseline tumor volume, followed by a dose expansion at the Recommended Phase II Dose (RP2D). Primary endpoints included RP2D determination, and early dose limiting toxicities (DLT). NBTXR3 intratumoral bioavailability and anti-tumor activity (RECIST 1.1) were also evaluated. Results: Enrollment was completed at all dose escalation levels: 5% (3 pts), 10% (3 pts), 15% (5 pts), and 22% (8 pts). No early DLT or SAE related to NBTXR3 or injection were observed. The median follow-up from NBTXR3 administration is 7.6 months. One AE (Grade 1) related to NBTXR3 and four AEs (Grade 1-2) related to the injection were observed. RT-related toxicity was as expected with IMRT. CT-scan assessment showed a good dispersion of NBTXR3 throughout the injected tumor and not in surrounding healthy tissues. The RP2D was determined to be 22%. Preliminary efficacy was evaluated in pts who received the intended dose of NBTXR3 and RT. A complete response of the injected lesion was observed in 9/13 (69%) evaluable pts at doses ≥10% (2 unconfirmed) and an overall complete response in 5/13 (38%) evaluable pts at doses ≥10%. Preliminary safety and efficacy data of the dose expansion cohort at the RP2D will also be presented. Conclusions: NBTXR3 activated by RT was well tolerated at all tested doses and demonstrated promising preliminary anti-tumor activity. Recruitment is ongoing in the dose expansion cohort. These results demonstrate that further testing of NBTXR3 in this population is warranted. Clinical trial information: NCT01946867 .

6069 Background: New therapeutic approaches are needed for elderly or frail head and neck squamous cell carcinoma (HNSCC) patients (pts) ineligible for standard of care treatment. NBTXR3, a crystalline solution of hafnium oxide nanoparticles may represent such an option. Injected intratumorally, NBTXR3 enters tumor cells and yields an increased cell-localized energy deposit upon exposure to radiotherapy (RT), leading to increased tumor cell death compared to the same dose of RT alone. Methods: Phase I study of NBTXR3 activated by RT in pts ≥70 years old or ≥65 years old and unable to receive cisplatin, eligible for exclusive RT with stage III or IV HNSCC of the oral cavity or oropharynx [NCT01946867]. A 3+3 dose escalation design was implemented with dose levels corresponding to 5%, 10%, 15% and 22% of baseline tumor volume, followed by an expansion phase. Pts received an intratumoral (IT) injection of NBTXR3 and intensity modulated RT (IMRT; 70 Gy/35 fractions/7 weeks). Determination of Recommended Phase 2 Dose (RP2D) and Dose Limiting Toxicities (DLT) were primary endpoints of phase I. Absence of NBTXR3 leakage and preliminary efficacy using RECIST 1.1 principles were also evaluated. Results: The dose-escalation is complete. Nineteen pts were enrolled: 3 at 5%, 3 at 10%; 5 at 15% and 8 at 22% with no observed DLT or SAE related to NBTXR3 or IT injection. One grade 1 NBTXR3-related AE (asthenia at 22%) and four IT injection-related AE (grade 2 oral pain; grade 1 tumor hemorrhage; grade 1 asthenia, and grade 1 injection site hemorrhage) were reported. RT-related toxicity was as expected with IMRT. RP2D has been determined to be 22%. CT-scan assessment between 24h and 7 weeks post-IT injection demonstrated absence of NBTXR3 leakage in the surrounding tissues. Among 13 evaluable pts treated at doses ≥10%, 9 achieved a complete response of the injected lesion. Conclusions: These results show that NBTXR3 activated by RT is safe and well tolerated at all doses with preliminary encouraging efficacy results. It thus represents a promising future treatment for frail and elderly pts with locally advanced HNSCC with limited therapeutic options. Expansion phase has started at the RP2D. Clinical trial information: NCT01946867.

TPS23 Background: Despite proven efficacy, a limited number of patients (pts) with recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) or metastatic non-small cell lung cancer (NSCLC) benefit from anti-PD-1 treatment. Indeed, most pts do not respond to initial therapy due to intrinsic resistance to checkpoint inhibition. There is thus an important unmet medical need for a curative treatment in these pts and converting the local immune microenvironment to a “hot” phenotype may help to overcome therapeutic resistance. Hafnium oxide nanoparticles (NBTXR3) activated by radiotherapy (RT) increase radiation dose deposit within cancer cells compared to RT alone. Recently, a phase II/III randomized trial of NBTXR3 in locally advanced soft tissue sarcoma (STS) met primary and main secondary endpoints with significant superiority compared to RT alone. Furthermore NBTXR3+RT demonstrated an immunogenic cell death-mediated abscopal effect in a pre-clinical setting, and immune cell infiltration was observed in some tumors from STS pts treated with NBTXR3+RT but not in tumors from pts treated with RT alone. NBTXR3 is currently being evaluated in 7 clinical trials, including a phase I/II study in elderly frail patients with locally advanced HNSCC. To date, no early dose limiting toxicities (DLTs) have been observed. Methods: Overall, these results have led us to evaluate NBTXR3 activated by stereotactic ablative radiotherapy (SABR) in combination with an approved anti-PD-1 antibody in an open label phase I/II, non-randomized clinical trial in pts with more advanced diseases: locoregionally recurrent or metastatic HNSCC, metastatic NSCLC, and liver metastasis pts. The phase I primary objectives are to determine NBTXR3 maximum tolerated dose(s), incidence of early DLTs and recommended dose(s). The phase II primary objectives are Complete Response Rate of target lesions and Objective Response Rate for the locoregional recurrent and the metastatic group respectively by RECIST 1.1, and safety/tolerability of treatment at the recommended dose(s). [NCT02379845] [NCT01946867]. Clinical trial information: NCT03589339.

6080 Background: Functionalized hafnium oxide nanoparticles (NBTXR3) have been developed as selective radioenhancers, which may represent a breakthrough approach for the local treatment of solid tumors. The high electron density of the nanoparticles, when exposed to radiotherapy (RT), allow the absorption/deposition of a high radiation dose within the tumor cells, to physically kill the cells and possibly improve outcome. A phase I trial was implemented for the treatment of locally advanced HNSCC in patients (pts) older than 65 years who cannot receive cisplatin. Methods: Pts received a single intratumor (IT) injection of NBTXR3, volume dose levels escalated at 5%, 10%, 15% and 22% of baseline tumor volume, followed by RT (IMRT, 70Gy/ 35 fractions / 7 weeks). Primary endpoints included feasibility of the IT implantation and safety. Secondary endpoints included IT residency of NBTXR3 using CT scan and RECIST 1.1 response. Results: Enrollment was completed for volume 5%, 10%, and 15% (11 pts) and 1 patient at volume dose level 22%. Feasibility of the IT injection was confirmed. The treatment was easily administered, was safe with no SAE, or early DLT, which allowed the pts for completion of the planned RT schedule. Adverse events related to the injection procedure included grade 1-2 injection pain (1 pt), and tumor hemorrhage (1 pt). Results demonstrated that a single injection of NBTXR3 provides adequate bioavailability of NBTXR3 IT over seven weeks of RT. No leakage of NBTXR3 to the adjoining healthy tissues was observed. Preliminary results of antitumor activity according to RECIST 1.1 are presented below: 11 evaluable pts, 10 showed complete or partial response (RECIST 1.1) including, 1/5 complete response at dose levels ≤ 10% and 3/6 complete responses at dose levels > 10% Follow up results with duration of response and tolerance will be disclosed. Conclusions: Injection of NBTXR3 was safe and well tolerated. All pts received the planned RT. Clinical trial information: NCT01946867.