ESTRO 38 Abstract book

S139 ESTRO 38

when activated by RT, thereby increasing tumor-specific physical killing through DNA damage/cell destruction and enhancing the immunogenic tumor cell death. Material and Methods Patients suffering from primary HCC (with/without portal vein tumor thrombosis) or liver mets were included and treated with a single intralesional injection (IL) of NBTXR3 followed by SBRT (45 Gy/3 fractions/5 to 7 days). The phase I part of the study was designed as a 3 + 3 escalation dose with tested dose levels at 10%, 15%, 22% and 33% of baseline tumor volume. Primary endpoints include the determination of the recommended dose and incidence of early dose limiting toxicities (DLTs). Secondary endpoints include assessment of global safety profile, characterization of the body kinetic profile, liver function evaluated by Child-Pugh score (CPS), AST to Platelet Ratio Index (APRI), and response rate (mRECIST/RECIST v1.1). Results The enrollment is complete in the first 3 dose levels: 10% (6 pts), 15% (4 pts) and 22% (4 pts) and is ongoing at the last IL dose level at 33% with no early DLTs, no AE related to NBTXR3, and no serious AE related to RT or the injection. So far, four AEs related to the IL were observed (Malaise, grade 2; two Abdominal pain, grade 3 and Bilateral pleural effusion, grade 1) at dose level 10%, 15% and 22% respectively. NBTXR3 remained localized within the tumor, validating the relevance of the single IL. No relevant change in CPS or APRI was observed over time which is consistent with the low toxicity observed. In 7 HCC pts evaluable for response, the mRECIST assessment by MRI on target lesions resulted in the following best observed response: 3 complete responses, 3 partial responses and 1 stable disease. In 5 evaluable liver mets pts, the RECIST v1.1 assessment by MRI on target lesions resulted in the following best observed response: 1 partial response, 3 stable disease and 1 local progressive disease. Conclusion NBTXR3 was well tolerated and showed a promising safety profile. Recruitment at the highest dose level of 33% is ongoing for the IL part and, once completed, will be followed by the expansion phase. NBTXR3 is also being evaluated in 6 other clinical trials, including a phase II/III trial in soft tissue sarcoma [NCT02379845] and phase I/II trials in prostate [NCT02805894], head and neck [NCT01946867] and rectum cancers [NCT02465593]. OC-0282 HDR brachytherapy Monotherapy for prostate cancer: a one-day schedule phase II trial acute toxicity M. Jolicoeur 1 , T.V. Nguyen 1 , T. Derashodian 1 , E. Hill 1 , M. Mondat 1 , M. Nachabe 1 , E. Antebi 1 , G. Wakil 1 , R. Héliou 1 1 CICM Hôpital Charles Le Moyne, Radiation Oncology, Greenfield Park, Canada Purpose or Objective To determine the early acute toxicity of a randomized phase II clinical trial of one 19.5 Gy fraction or two 14.5 Gy fractions of high-dose-rate (HDR) brachytherapy monotherapy delivered on a one day schedule. Material and Methods 205 patients with low or intermediate-risk prostate cancer were randomized between one fraction of 19.5Gy (Arm 1) or two fractions of 14.5Gy (Arm 2) on an HDR brachytherapy as monotherapy protocol (BRP2, NCT03424694), this the report of acute toxicities for the first 170 patients. Treatments were delivered with a single implant on a one- day schedule. All patients had a post implant MRI based dosimetry with dominant intra prostatic lesion (DIL) boost Proffered Papers: BT 3: Prostate HDR brachytherapy

Purpose or Objective Reirradiation (reRT) was applied with concomitant bevacizumab (BEV) for glioma patients with tumour recurrence as in-house standard until 2016 in our department. After disapproval of BEV of the European Medical Agency for glioma treatment, BEV was no longer applied as concomitant therapy in the reRT setting. As treatment related side effects seemed to increase without concomitant BEV, we investigated the rate of radiation necrosis (RN) and RN related symptomatic edema in patients treated with reRT with and without concomitant BEV. Material and Methods Glioma patients with tumour recurrence treated with reRT between April 2007 and December 2017 in our department were included into the cohort study. Study endpoints were the occurrence of RN and a compound endpoint of RN and/or symptomatic edema (RNSE). RN was diagnosed in contrast-enhanced MRI and verified in FET PET or histopathological examination after stereotactical biopsy, if available. Univariate and multivariate logistic regression analysis were performed to assess factors significantly related to the risk of RN and RNSE. Results 161 patients were included into the cohort study, of which 124 were treated with BEV and 37 without BEV concomitant to reRT. RN was detected in 6/124 patients treated with reRT with (4.8%) and in 5/37 patients treated with reRT without concomitant BEV (13.5%; p = 0.078, p = 0.02 on univariate and multivariate logistic regression analysis respectively). RN-free survival was significantly related to concomitant BEV treatment to reRT (p = 0.025 on log-rank test; p = 0.036, p = 0.013 on univariate and multivariate cox-regression analysis respectively) and prescribed dose (p = 0.002; p = 0.001, p = 0.001). Conclusion ReRT with concomitant BEV was significantly related to a lower rate of neurologic toxicity in our large monocentric cohort. Therefore, we strongly advise the use of concomitant BEV to reRT for glioma patients at tumour recurrence. OC-0281 Phase I/II trial of hafnium oxide nanoparticles activated by SBRT in the treatment of liver cancers E. Chajon 1 , M. Pracht 2 , T. De Baere 3 , F. N’Guyen 3 , J. Bronowicki 4 , V. Vendrely 5 , A. Baumann 6 , V. Croisé- Laurent 4 , E. Rio 7 , Y. Rolland 1 , S. Le Sourd 1 , P. Gustin 3 , C. Perret 7 , F. Mornex 8 , D. Peiffert 9 , P. Merle 8 , E. Deutsch 3 1 Centre Eugène Marquis, Radiotherapy, Rennes CEDEX, France; 2 Centre Eugène Marquis, Medical oncology, Rennes CEDEX, France ; 3 Gustave Roussy, General surgery, Villejuif, France; 4 Hôpital de Brabois Adultes, Hepato-gastro-enterology, Nancy, France; 5 Groupe Hospitalier Sud - Hôpital Haut-Lévêque, Ratiotherapy, Bordeaux, France; 6 Hôpital de Brabois Adultes, Radiotherapy, Nancy, France; 7 ICO - Site René Gauducheau, Radiotherapy, Saint Herblain Cedex, France ; 8 Centre Hospitalier de la Croix Rousse, Hepato- gastro-enterology, Lyon, France; 9 Institut de Cancérologie de Lorraine, Radiotherapy, Nancy, France Purpose or Objective Patients with hepatocellular carcinoma (HCC) and liver metastasis (mets) present with a wide range of underlying liver dysfunctions and concomitant malignancies. Stereotactic body radiation therapy (SBRT) is well- tolerated and a valuable alternative for patients who are not eligible for invasive procedures. Yet, like all radiation therapy (RT) techniques, the energy dose deposit to tumor cells is limited by the surrounding healthy tissues. NBTXR3, composed of hafnium oxide nanoparticles, was designed to effectively absorb ionizing radiation and augment the dose deposit within the tumor cells only