Summary

Purpose/Objective(s): Immune checkpoint inhibitors (ICIs) have led to improved treatment outcomes in a variety of cancers; however, the majority of patients exhibit resistance to ICIs. Overcoming this resistance is a major challenge in immune-oncology. Radiation therapy (RT) has emerged as a promising combination with ICIs since it may act synergistically with ICIs by producing an immunomodulatory effect. NBTXR3, composed of functionalized hafnium oxide nanoparticles, is injected intratumorally and activated by RT. NBTXR3 increases RT energy deposit inside tumor cells and subsequent tumor cell death, without adding toxicity to healthy tissues. Preclinical data demonstrate NBTXR3/RT can trigger a local and systemic anti-tumor immune response and overcome anti-PD-1 resistance. NBTXR3/RT combined with anti-PD-1 may prime the immune system to increase the proportion of ICI responders or convert ICI non-responders to responders.

Materials/Methods: This multicenter, open-label, phase I trial [NCT03589339] is evaluating NBTXR3/RT/anti-PD-1 in 3 cohorts: (1) Locoregional recurrent or recurrent and metastatic head and neck squamous cell carcinoma (HNSCC) amenable to HN re-irradiation and (2) lung or (3) liver metastases from any primary cancer eligible for anti-PD-1. Stereotactic body RT (SBRT) is delivered at tumor-site selective doses per standard practice. The primary objective is to determine the NBTXR3/RT/anti-PD-1 recommended phase 2 dose in each cohort. Secondary objectives are anti-tumor response (objective response rate), safety, and feasibility of NBTXR3 injection.

Results: Nine patients have been treated: 3 HNSCC, 4 lung, 2 liver. Overall tumor regression was observed in 8/9 patients of which 7 were anti-PD-1 non-responders. A complete response lasting over 1 year was observed in the injected lymph node in 1 anti-PD-1 naïve patient. 2 SAEs related to anti-PD-1 and possibly related to NBTXR3 (G5 pneumonitis, G4 hyperglycemia) were observed in 1 anti-PD-1 naïve HNSCC patient and considered DLTs. This patient also experienced 2 other G4 SAEs related to anti-PD-1 (diabetic ketoacidosis, acute kidney injury). SBRT-related safety profile was as expected. Updated safety and efficacy results with additional patients and longer follow-up will be presented.

Conclusion: Safety data from this first-in-human phase I trial evaluating NBTXR3/RT/anti-PD-1 in patients with advanced cancers, show NBTXR3 intratumoral injection is feasible and well-tolerated in HNSCC, lung, and liver. NBTXR3/RT/anti-PD-1 demonstrated promising signs of efficacy and led to tumor regression in patients having progressed on prior anti-PD-1. These data support further development of NBTXR3 in combination with anti-PD-1 as well as other ICIs.

Summary

Purpose/Objective(s): Immune checkpoint inhibitors (ICIs) have led to improved treatment outcomes in a variety of cancers; however, the majority of patients exhibit resistance to ICIs. Overcoming this resistance is a major challenge in immune-oncology. Radiation therapy (RT) has emerged as a promising combination with ICIs since it may act synergistically with ICIs by producing an immunomodulatory effect. NBTXR3, composed of functionalized hafnium oxide nanoparticles, is injected intratumorally and activated by RT. NBTXR3 increases RT energy deposit inside tumor cells and subsequent tumor cell death, without adding toxicity to healthy tissues. Preclinical data demonstrate NBTXR3/RT can trigger a local and systemic anti-tumor immune response and overcome anti-PD-1 resistance. NBTXR3/RT combined with anti-PD-1 may prime the immune system to increase the proportion of ICI responders or convert ICI non-responders to responders.

Materials/Methods: This multicenter, open-label, phase I trial [NCT03589339] is evaluating NBTXR3/RT/anti-PD-1 in 3 cohorts: (1) Locoregional recurrent or recurrent and metastatic head and neck squamous cell carcinoma (HNSCC) amenable to HN re-irradiation and (2) lung or (3) liver metastases from any primary cancer eligible for anti-PD-1. Stereotactic body RT (SBRT) is delivered at tumor-site selective doses per standard practice. The primary objective is to determine the NBTXR3/RT/anti-PD-1 recommended phase 2 dose in each cohort. Secondary objectives are anti-tumor response (objective response rate), safety, and feasibility of NBTXR3 injection.

Results: Nine patients have been treated: 3 HNSCC, 4 lung, 2 liver. Overall tumor regression was observed in 8/9 patients of which 7 were anti-PD-1 non-responders. A complete response lasting over 1 year was observed in the injected lymph node in 1 anti-PD-1 naïve patient. 2 SAEs related to anti-PD-1 and possibly related to NBTXR3 (G5 pneumonitis, G4 hyperglycemia) were observed in 1 anti-PD-1 naïve HNSCC patient and considered DLTs. This patient also experienced 2 other G4 SAEs related to anti-PD-1 (diabetic ketoacidosis, acute kidney injury). SBRT-related safety profile was as expected. Updated safety and efficacy results with additional patients and longer follow-up will be presented.

Conclusion: Safety data from this first-in-human phase I trial evaluating NBTXR3/RT/anti-PD-1 in patients with advanced cancers, show NBTXR3 intratumoral injection is feasible and well-tolerated in HNSCC, lung, and liver. NBTXR3/RT/anti-PD-1 demonstrated promising signs of efficacy and led to tumor regression in patients having progressed on prior anti-PD-1. These data support further development of NBTXR3 in combination with anti-PD-1 as well as other ICIs.

Summary

Introduction: Immune checkpoint inhibitors (ICIs) have improved treatment outcomes in a variety of cancers; however the majority of patients (pts) exhibit resistance. Emerging evidence suggests radiation therapy (RT) can enhance response to ICIs by producing an immunomodulatory effect. NBTXR3, composed of functionalized hafnium oxide nanoparticles, is injected intratumorally and activated by RT. NBTXR3 increases RT energy deposition inside tumor cells and subsequent tumor cell death, without adding toxicity to healthy tissues. Preclinical data demonstrate NBTXR3/RT can trigger a local and systemic anti-tumor immune response and overcome anti-PD-1 resistance. NBTXR3/RT combined with anti-PD-1 may prime the immune system to increase the proportion of ICI responders or convert ICI non-responders to responders.

Materials and Methods: A multicenter, open-label, phase I trial [NCT03589339] evaluating NBTXR3/SBRT/anti-PD-1 (nivolumab or pembrolizumab) in 3 cohorts (1) Locoregional recurrent or recurrent and metastatic HNSCC amenable to HN re-irradiation, (2) lung or (3) liver metastases from any primary cancer eligible for anti-PD-1. Stereotactic body RT (SBRT) is delivered at tumor-site specific doses per standard practice. Primary objective is to determine the NBTXR3/SBRT/anti-PD-1 recommended phase 2 dose in each cohort. Secondary objectives are anti-tumor response (objective response rate), safety, and feasibility of NBTXR3 injection.

Results: Nine pts have been treated, 3 HNSCC, 4 lung and 2 liver. HNSCC was the primary cancer in 2 pts in the lung and 1 pt in the liver cohort. 7/9 pts were anti-PD-1 non-responders. Overall tumor regression was observed in 8/9 pts. NBTXR3/SBRT/anti-PD-1 resulted in tumor regression in 6/7 pts who had progressed on prior anti-PD-1. One anti-PD-1 naïve HNSCC pt achieved a complete response lasting over a year in the injected lymph node. 2 SAEs related to anti-PD-1 and possibly related to NBTXR3 (G5 pneumonitis, G4 hyperglycemia) were observed in 1 anti-PD-1 naïve HNSCC pt and considered DLTs. This pt also experienced 2 other SAEs (G4 diabetic ketoacidosis, G4 acute kidney injury) related to anti-PD-1. SBRT-related safety profile was as expected.

Conclusions: Safety data from this first-in-human phase I trial evaluating NBTXR3/SBRT/anti-PD-1 in pts with advanced cancers show NBTXR3 intratumoral injection is feasible and well-tolerated in HNSCC, lung, and liver metastases. NBTXR3/SBRT/anti-PD-1 demonstrated promising signs of efficacy and led to tumor regression in pts having progressed on prior anti-PD-1. These data support further development of NBTXR3/SBRT in combination with anti-PD-1 as well as other ICIs.

Summary

Background: NBTXR3, a first-in-class radioenhancer composed of functionalized hafnium oxide nanoparticles, is administered by one time intratumoral injection (ITI) and activated by radiotherapy (RT), such as stereotactic body RT (SBRT). NBTXR3 increases RT energy deposit inside tumor cells and subsequently increases tumor cell death compared to RT alone, while sparing healthy tissues. SBRT is well-tolerated in hepatocellular carcinoma (HCC) or liver metastases (mets) and a valuable alternative for patients not eligible for surgery or radiofrequency ablation. However, energy dose deposit to tumor cells is limited due to potential toxicity to surrounding healthy tissues. Patients with unresectable liver cancers including patients with liver or renal dysfunction might benefit from NBTXR3. A Phase 1 clinical trial was conducted to evaluate the safety and Recommended Phase 2 Dose (RP2D) of NBTXR3 activated by SBRT [NCT02721056] in these patients, here we report the results.

Methods: A 3+3 dose escalation scheme tested 5 NBTXR3 levels: 10, 15, 22, 33, and 42% of baseline tumor volume. NBTXR3 ITI was followed by SBRT (45 Gy / 3 fractions / 5-7 days or 50 Gy / 5 fractions / up to 15 days) in patients with HCC or liver mets. Primary endpoints included RP2D determination and early DLT incidence. Secondary endpoints include safety profile, liver disease scores evolution, and early efficacy by response rate (mRECIST for HCC/RECIST 1.1 for liver mets).

Results: 23 patients were treated: 6 patients at 10% (2 SBRT doses tested due to organ constraints), 4 patients each at 15% and 22% (due to fiducial displacement and ITI shift), 3 patients at 33% and 6 patients at 42%. No early DLT was observed at any dose level. 1 SAE (grade 3 late onset bile duct stenosis) related to NBTXR3 and RT occurred at 22%. There were 11 AEs related to NBTXR3 and/or ITI, of which grade 3 AEs were: 2 abdominal pain (ITI related; 15%) and 1 late onset bile duct stenosis (22%), lesion close to the bile duct. No NBTXR3 or ITI related grade 4-5 AEs were observed. RT related AEs were as expected with SBRT. No clinically meaningful changes in Child-Pugh score or APRI were observed post-treatment. CT-scan showed NBTXR3 present within the tumor without leakage to surrounding healthy tissues. Best observed responses (MRI) in injected target lesions from HCC patients (n = 15) were 5 CRs (33.3%), 5 PRs(33.3%), 1 SD (6.7%), 2 NE (13.3%), 2 patients did not have post baseline MRI and for liver mets (n = 8) were 5 PRs (62.5%), 2 SD (25.0%) and 1 NE (12.5%).

Conclusions: No early DLTs were observed and NBTXR3 demonstrated a good safety and tolerability profile. The RP2D was determined to be 42% of tumor volume. Initial efficacy is promising and highlights the potential for NBTXR3 to address an unmet medical need in patients with unresectable primary or metastatic liver cancers.

Summary

Background: Cancer immunotherapies have shown promising clinical outcomes; however, the majority of patients are non-responders or will develop resistance during the course of treatment. One of the current challenges is to increase the response rate to immune checkpoint inhibitors (ICIs). Combining immunotherapy with radiation therapy (RT) is emerging as a valuable strategy to prime the immune response. However, RT dose and ultimate efficacy are limited by toxicity related to exposure of healthy tissues. First-in-class radioenhancer NBTXR3, administered by one-time direct intratumoral injection, is designed at the nanoscale to increase RT dose deposit with subsequent increase in tumor cell killing, without increasing toxicity to normal tissue. Preclinical and early clinical data suggest NBTXR3/RT can prime the immune system and act as an in situ vaccine leading to an anti-tumor immune response, producing both local and systemic (abscopal) effects. We hypothesize NBTXR3/RT in combination with anti-PD-1 (NBTXR3/RT/PD-1), will act synergistically to increase the proportion of ICI responders or convert ICI non-responders to responders.

Methods: A multicenter, open-label, phase I trial [NCT03589339] evaluating safety and tolerability of NBTXR3/RT/PD-1 in three cohorts: (1; H&N) Locoregional recurrent or recurrent and metastatic head and neck squamous cell carcinoma (HNSCC) amenable to re-irradiation of the HN field, (2; lung) lung or (3; liver) liver metastases from any primary cancer eligible for approved anti-PD-1 treatment. NBTXR3 injected volume is based on a percentage of baseline tumor volume. Stereotactic body RT (SBRT) is delivered as per standard practice. The primary objective is to determine NBTXR3/RT/PD-1 recommended phase II dose in each cohort. Secondary objectives are to evaluate anti-tumor response (objective response rate), safety and feasibility of NBTXR3 injection, and NBTXR3 body kinetic profile.

Results: To date 6 patients have been treated: 3 in H&N (2 anti-PD-1 naïve) and 3 in lung (all anti-PD-1 non-responders. No DLT or SAE has been observed. Grade 2 nausea related to NBTXR3 or injection procedure was observed in H&N. 2 H&N patients and 3 lung patients have completed RT and initiated anti-PD-1 treatment. RT-related safety profile was as expected. Tumor shrinkage was observed in 1 anti-PD-1 naive and 2 anti-PD-1 non-responders and additional preliminary efficacy and updated safety results will be presented.

Conclusions: To date, NBTXR3 administration activated by SBRT in combination with anti-PD-1 treatment has been safe and well tolerated in patients with advanced cancers. Promising early signs of efficacy in anti-PD-1 naïve, as well as in patients having progressed on previous anti-PD-1 therapy will be presented.

Summary

Purpose/Objective: The use of stereotactic body radiotherapy (SBRT) for the local control of unresectable hepatocellular carcinoma (HCC) or liver metastases (mets) is well tolerated but limited by the need to preserve liver function. Increasing energy deposit within the tumor without increasing toxicity in healthy tissues remains a major challenge in radiation oncology. NBTXR3 (hafnium oxide nanoparticles), a first-in-class radioenhancer when activated by RT augments energy dose deposit within tumor cells, increasing tumor cell death compared to RT alone, while sparing healthy tissues. Patients (pts) with HCC or mets may benefit from the mode of action of NBTXR3. A phase I/II clinical trial has been conducted to evaluate NBTXR3 activated by SBRT in these pts [NCT02721056].

Material/Methods: The Phase I is a 3+3 dose escalation scheme with 5 NBTXR3 dose levels: 10, 15, 22, 33, and 42% of baseline tumor volume. NBTXR3 has been administered by intratumoral injection (ITI) followed by SBRT (45 Gy / 3 fractions / 5 to 7 days or 50 Gy / 5 fractions / 15 days). Primary endpoints were determination of the RP2D and early DLTs. Secondary endpoints included the safety profile, liver disease scores evolution, and early efficacy by response rate (mRECIST/RECIST 1.1).

Results: Twenty pts have been treated. The dose levels of 10, 15, 22 and 33% are completed: 6 pts at 10% (2 SBRT doses tested due to organ constraints), 4 pts each at 15% and 22% (due to fiducial displacement and ITI shift) and 3 pts at 33%. The final (42%) dose escalation level is ongoing with 3 pts treated thus far. No early DLT has been observed. One SAE (G3 bile duct stenosis) related to NBTXR3 and RT occurred at the 22% dose level. Adverse events related to ITI or NBTXR3 were: G2 malaise at the 10% dose level, 2 G3 abdominal pain at 15%, G1 pleural effusion and G3 bile duct stenosis at 22% and G1 fatigue at 33%. No clinically meaningful changes in CPS and APRI were observed post-treatment and CT-scan showed no leakage of NBTXR3 into surrounding healthy tissues. Best observed response in evaluable patients for HCC (n=8) were 5 CR, 3 PR and for mets (n=5) the results were: 4 PR, 1 SD.

Conclusion: Intratumoral injection of NBTXR3 is feasible, demonstrated a very good safety and tolerability profile up to the 42% dose level. Recruitment at the 42% dose level is nearly finalized. Early efficacy results suggest NBTXR3 has the potential to address an unmet medical need in pts with unresectable primary or metastatic liver cancer.

Summary

Purpose/Objective(s): Stereotactic body radiotherapy (SBRT) is a well-tolerated and valuable alternative for patients with unresectable hepatocellular carcinoma (HCC) or liver metastases (mets) who are not eligible for standard treatment such as surgery, local ablation or chemoembolization. Yet, the energy dose delivered to the tumor is limited due to potential toxicity to healthy tissues and the need to preserve liver function. Thus, achieving local control in liver cancers remains a challenge. The first-in-class radioenhancer NBTXR3 (hafnium oxide nanoparticles), administered by intratumoral (IT) injection once prior to RT treatment, augments the energy dose deposit within tumor cells when activated by RT. The result is increased tumor cell death compared to RT alone without increasing radiation exposure to surrounding tissues. Patients with HCC or mets may benefit from this new approach. Here we report on a phase I/II study evaluating NBTXR3 activated by SBRT in these patients.

Materials/Methods: In the phase I part of the study [NCT02721056], five NBTXR3 dose levels equivalent to 10, 15, 22, 33, and 42% of baseline tumor volume are tested following a traditional 3+3 design. NBTXR3 is administered by IT injection followed by SBRT (45 Gy / 3 fractions / 5-7 days or 50 Gy / 5 fractions / 15 days). Primary endpoints include determination of the recommended phase 2 dose (RP2D) based on the incidence of the early DLTs. Secondary endpoints include the safety profile, liver disease scores evolution, and early efficacy by target lesions response rate (mRECIST/RECIST 1.1).

Results: To date, 22 patients have been treated and the 4 first dose levels are completed with 6 patients at 10% (2 SBRT doses tested due to organ constraints), 4 patients each at 15% and 22% (due to fiducial displacement and incomplete injected dose) and 3 patients at 33%. The last dose level (42%) is ongoing with 5 patients treated so far. No early DLT has been observed at any dose level. Five AEs (3 G1-2; 2 G3) related to the injection and 4 AEs related to NBTXR3 (3 G1-2; 1 G3), including 1 SAE (bile duct stenosis, also related to RT) were observed. No grade 4-5 AEs were observed. CT-scan showed no leakage of NBTXR3 into surrounding healthy tissues and SBRT safety profile was as expected. No clinically meaningful changes in CPS and APRI were observed post-treatment. In patients evaluable for efficacy, best observed target lesion responses were 5 complete response and 3 partial response in HCC patients (n = 8) and, 5 partial response and 1 stable disease in liver mets patients (n = 6).

Conclusion: NBTXR3 intratumoral injection is feasible and NBTXR3 demonstrates a very good safety and tolerability profile thus far. Recruitment is nearly completed at the 42% dose level. Early efficacy results highlight the potential for NBTXR3 to improve the clinical outcomes of patients with unresectable primary or metastatic liver cancer.

Summary

Background: NBTXR3, functionalized hafnium oxide nanoparticles, administered by intratumoral injection (ITI) and activated by radiotherapy (RT), such as stereotactic body RT (SBRT), increases energy deposit inside tumor cells and subsequently tumor cell death compared to RT alone, while sparing healthy tissues. This innovative approach, which does not engage liver and renal functions, might benefit patients (pts) with unresectable liver cancers.

Methods: Phase I/II clinical trial to evaluate NBTXR3 administered by ITI activated by SBRT (45 Gy / 3 fractions / 5-7 days or 50 Gy / 5 fractions / up to 15 days) in pts with hepatocellular carcinoma (HCC) or liver metastases [NCT02721056]. Phase I 3+3 dose escalation scheme with 5 NBTXR3 dose levels: 10, 15, 22, 33, and 42% of baseline tumor volume. Primary endpoints include Recommended Phase II Dose (RP2D) determination and early DLT incidence. Secondary endpoints include safety profile, liver disease scores evolution, and early efficacy by response rate (mRECIST/RECIST 1.1).

Results: Enrolment at all dose levels is complete, 23 pts treated: 6 pts at 10% (2 SBRT doses tested due to organ constraints), 4 pts each at 15% and 22% (due to fiducial displacement and ITI shift), 3 pts at 33% and 6 pts at 42%. No early DLT was observed at any dose level. 1 SAE (late onset G3 bile duct stenosis) related to NBTXR3 and RT occurred at 22%. No clinically meaningful changes in Child-Pugh score and APRI were observed post-treatment. There were 11 AEs related to NBTXR3 and/or ITI, of which grade 3 AEs were: 2 abdominal pain (ITI related) and 1 bile duct stenosis (NBTXR3 related) No grade 4-5 AEs were observed. CT-scan showed NBTXR3 within tumor without leakage to healthy tissues. To date, the best observed responses assessed by MRI in target lesions from evaluable pts for HCC (n=11) were 5 CR, 5 PR, 1 SD and for metastases (n=7) 5 PR, 2 SD.

Conclusions: NBTXR3 has demonstrated a very good safety and tolerability profile in these patient populations. The RP2D has been determined to be 42% of tumor volume. Early efficacy results highlight the potential for NBTXR3 to address an unmet medical need in pts with unresectable primary or metastatic liver cancer.

Summary

Background: Despite the past decade of transformative advances in immuno-oncology, the response rate to checkpoint inhibitors (ICIs) remains low (~15%). There is significant interest in developing strategies to overcome resistance to these treatments, thus increasing response rate. Emerging evidence suggests that radiation therapy (RT) could potentially augment the antitumor response to ICIs through synergic effect. However, RT dose and ultimate efficacy are limited by toxicity related to exposure of healthy tissues. NBTXR3 is a first-in-class radioenhancer administered by direct intratumoral injection, designed at the nanoscale to increase RT dose deposition within tumor cells and RT-dependent tumor cell killing, without increasing surrounding normal tissue toxicity. Preclinical and early clinical data suggest NBTXR3 activated by RT can trigger an anti-tumor immune response, producing both local and systemic (abscopal) effects. We hypothesize that NBTXR3 activated by RT, in combination with anti-PD-1 therapy (R3/RT/PD-1), will act synergistically to maximize the local RT effect and produce a systemic response sufficient to increase the proportion of ICI responders or convert ICI non-responders to responders.

Method: This trial [NCT03589339] is a multicenter, open-label, phase I study to evaluate safety and tolerability of R3/RT/PD-1 in three cohorts: (1) Locoregional recurrent or recurrent and metastatic head and neck squamous cell carcinoma (HNSCC) amenable to re-irradiation of the HN field, (2) Lung metastases, or (3) Liver metastases, both from any primary cancer eligible for anti-PD-1 treatment. Approximately two-thirds of patients in each cohort will be anti-PD-1 non-responders. NBTXR3 injected volume is based on a percentage of gross tumor volume (GTV). The primary objective is to determine the R3/RT/PD-1 recommended phase 2 dose in each cohort. Secondary objectives are to evaluate anti-tumor response (objective response rate; ORR), safety and feasibility of NBTXR3 injection, and NBTXR3 body kinetic profile. Exploratory objectives will assess biomarkers of R3/RT/PD-1 response, including PD-L1 status by IHC, as well as mRNA and cytokine immune marker profiling. To date, three patients have been treated, one in cohort 1, two in cohort 2.

Summary

Background: Treatment of unresectable liver cancer or liver metastases (mets) by stereotactic body radiotherapy is well tolerated but limited by the need to preserve liver function. Increasing energy deposition in the tumor while at the same time maintaining the dose in healthy tissue remains a major challenge in radiation oncology that could be achieved by NBTXR3 (hafnium oxide nanoparticles) when activated by radiotherapy (RT). NBTXR3 augments energy dose deposit within tumor cells, increasing tumor cell death compared to RT alone, while sparing healthy tissues.
Patients (pts) with hepatocellular carcinoma (HCC) or liver metastasis (mets) may benefit from the mode of action of NBTXR3. A phase I/II clinical trial has been conducted to evaluate NBTXR3 activated by SBRT in these pts [NCT02721056].

Materials/Methods: The Phase I used a 3+3 dose escalation scheme with 5 NBTXR3 dose levels: 10, 15, 22, 33, and 42% of baseline tumor volume. NBTXR3 was administered by intratumoral injection (ITI) followed by SBRT (45 Gy / 3 fractions / 5 to 7 days or 50 Gy / 5 fractions / 15 days). Primary endpoints were identification of the recommended Phase II Dose and early DLTs. Secondary endpoints included safety profile, liver function evaluated by Child-Pugh score (CPS), AST to Platelet Ratio Index (APRI), and early efficacy by response rate (mRECIST/RECIST 1.1).

Results: The dose escalation levels of 10, 15, 22 and 33% are completed (n=17): 6 pts at 10% (2 SBRT doses tested due to organ constraints), 4 pts each at 15% and 22% (due to fiducial displacement and ITI shift) and 3 pts at 33%. No early DLT was observed and only one SAE (bile duct stenosis) related to NBTXR3 and RT occurred. CPS and APRI did not show clinically meaningful changes post-treatment and CT-scan showed no leakage of NBTXR3 into surrounding tissues. Best response for HCC (n=8) were 5CR, 3PR and for mets (n=6) the results were: 3 PR, 3SD.

Conclusion: ITI of NBTXR3 is feasible, demonstrated a very good safety and tolerability profile up to the 33% dose level. Recruitment needs to be finalized at the 42% dose level. Based on early efficacy results NBTXR3 has the potential to address an unmet medical need in pts with unresectable primary or metastatic liver cancer.