Assessment of Sodium MRI at 7 Tesla as Predictor of Therapy Response and Survival in Glioblastoma Patients

The purpose of this work was to prospectively investigate sodium (23Na) MRI at 7 Tesla (T) as predictor of therapy response and survival in patients with glioblastoma (GBM). Thus, 20 GBM patients underwent 23Na MRI at 7T before, immediately after and 6 weeks after chemoradiotherapy (CRT). The median tissue sodium concentration (TSC) inside the whole tumor excluding necrosis was determined. Initial response to CRT was assessed employing the updated response assessment in neuro-oncology working group (RANO) criteria. Clinical parameters, baseline TSC and longitudinal TSC differences were compared between patients with initial progressive disease (PD) and patients with initial stable disease (SD) using Fisher’s exact tests and Mann-Whitney-U-tests. Univariate proportional hazard models for progression free survival (PFS) and overall survival (OS) were calculated using clinical parameters and TSC metrics as predictor variables. The analyses demonstrated that TSC developed heterogeneously over all patients following CRT. None of the TSC metrics differed significantly between cases of initial SD and initial PD. Furthermore, TSC metrics did not yield a significant association with PFS or OS. Conversely, the initial response according to the RANO criteria could significantly predict PFS [univariate HR (95%CI) = 0.02 (0.0001–0.21), p < 0.001] and OS [univariate HR = 0.17 (0.04–0.65), p = 0.005]. In conclusion, TSC showed treatment-related changes in GBM following CRT, but did not significantly correlate with the initial response according to the RANO criteria, PFS or OS. In contrast, the initial response according to the RANO criteria was a significant predictor of PFS and OS. Future investigations need to elucidate the reasons for treatment-related changes in TSC and their clinical value for response prediction in glioblastoma patients receiving CRT.

PET/MR in recurrent glioblastoma patients treated with regorafenib: [18F]FET and DWI-ADC for response assessment and survival prediction

Objectives: The use of regorafenib in recurrent glioblastoma patients has been recently approved by the Italian Medicines Agency (AIFA) and added to the National Comprehensive Cancer Network (NCCN) 2020 guidelines as a preferred regimen. Given its complex effects at the molecular level, the most appropriate imaging tools to assess early response to treatment is still a matter of debate. DWI and [18F]FET PET are promising methodologies providing additional information to the currently used RANO criteria. The aim of this study was to evaluate the variations in DWI/ADC- and [18F]FET PET-derived parameters in patients who underwent PET/MR at both baseline and after starting regorafenib. Methods: We retrospectively reviewed 16 consecutive GBM patients who underwent [18F]FET PET/MR before and after two cycles of regorafenib. Patients were sorted into stable (SD) or progressive disease (PD) categories in accordance with RANO criteria. We were also able to analyze 4 SD patients who underwent a third PET/MR after another 4 cycles of regorafenib. [18F]FET uptake greater than 1.6 times the mean background activity was used to define an area to be superimposed on an ADC map at baseline and after treatment. Several metrics were then derived and compared. Log-rank test was applied for overall survival analysis. Results: Percentage difference in FET volumes correlates with the corresponding percentage difference in ADC (R = 0.54). Patients with a twofold increase in FET after regorafenib showed a significantly higher increase in ADC pathological volume than the remaining subjects (p = 0.0023). Kaplan-Meier analysis, performed to compare the performance in overall survival prediction, revealed that the percentage variations of FET and ADC derived metrics performed at least as well as RANO criteria (p = 0.02, p = 0.024 and p = 0.04 respectively) and in some cases even better. TBR Max and TBR mean are not able to accurately predict overall survival. Conclusion In recurrent glioblastoma patients treated with regorafenib, [18F]FET and ADC metrics, are able to predict overall survival and being obtained from completely different measures as compared to RANO, could serve as semi-quantitative independent biomarkers of response to treatment. Advances in knowledge Simultaneous evaluation of [18F]FET and ADC metrics using PET/MR allows an early and reliable identification of response to treatment and predict overall survival.

NIMG-24. RANO CRITERIA DETECTS EARLY PROGRESSION SOONER THAN MODIFIED RANO CRITERIA IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

BACKGROUND Accurate response criteria are crucial for determining treatment efficacy. The response assessment in neuro-oncology (RANO) criteria was developed to standardize response assessment in neuro-oncology. Modified RANO (m-RANO) criteria were recently proposed to address some limitations of the initial criteria including the use of a post-radiation baseline and an additional scan to confirm progression. We sought to identify differences in the association of progression-free survival (PFS) and overall survival (OS) using RANO and m-RANO criteria. METHODS We conducted a retrospective review of newly diagnosed glioblastoma (GBM) patients treated at Dana-Farber Cancer Institute from January 2013 until December 2019. Patients with available clinical and imaging data obtained before initiation of treatment, after radiation completion and at intervals of 1 to 3 months were included. MRIs were evaluated by two independent readers, and PD dates determined using RANO and m-RANO criteria. RESULTS 552 patients were included. 97.1% of the tumors were IDH wild-type. MGMT promoter was unmethylated in 51.4%, methylated in 35.1% and undetermined in 8.5%. Median OS among patients was 18.1 months. 72 patients (13%) did not have PD at the end of the study. 83 patients had treatment change while being clinically stable and without a confirmation scan and were excluded from the final analysis. PFS was 8.2 months with RANO and 8.4 months with mRANO. Difference in PD dates between RANO and m-RANO was detected in 76 patients (14%), where PFS was 3.5 months with RANO and 5.1 months with m-RANO. These patients had a worse median OS than those with identical RANO and m-RANO PD dates (15.2 vs. 22.4 months, p< 0.0001). CONCLUSION RANO and m-RANO criteria resulted in identical PFS for most patients. 14% of patients had discordant PD dates and a worse prognosis. These patients progressed early, and their PD was identified sooner with RANO criteria.

NIMG-27. REGORAFENIB RESPONSE ASSESSMENT USING FET PET IN PATIENTS WITH PROGRESSIVE GLIOMA

BACKGROUND The REGOMA phase 2 trial showed an encouraging overall survival benefit of the multikinase inhibitor regorafenib in glioblastoma patients at first progression. We used O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET for the early assessment of response to regorafenib in patients with progressive glioma in an advanced disease stage. METHODS Thirty patients with progressive glioma were treated according to the REGOMA trial and prospectively followed. FET PET and MRI were performed at baseline and after the second cycle of regorafenib. Static PET parameters such as maximum and mean tumor-to-brain ratios (TBRmax, TBRmean) and metabolic tumor volumes (MTV) were calculated. Threshold values of FET PET parameters to predict a response were established by ROC analyses using an overall survival of ≥ 6 months as reference. The predictive value of FET PET parameters and their changes concerning overall survival was subsequently evaluated using the Kaplan-Meier test. MRI changes were evaluated according to the RANO criteria. RESULTS Up to now, 18 of 30 patients (glioblastoma, 83%; age range, 24-71 years) were eligible for data evaluation. The median number of tumor relapses before regorafenib was 2 (range, 1-4). During regorafenib (median cycles, 4; range, 2-9 cycles), CTCAE grade 3 or 4 side effects occurred in 56% and 11%, respectively. The median overall survival was 6 months (range, 3-18 months). After two cycles of regorafenib, a TBRmean reduction of 13% predicted a significantly longer overall survival (12 vs. 6 months; P=0.034). In contrast, MRI changes evaluated according to RANO criteria (i.e., Stable Disease or Partial Response vs. Progressive Disease) were not predictive (11 vs. 8 months; P=0.644). CONCLUSION Data suggest that amino acid PET using the tracer FET may be clinically valuable for identifying responders to regorafenib early after treatment initiation.

BIOM-24. PROTEIN SURFACE SIGNATURE ON SERUM EXTRACELLULAR VESICLES FOR NON-INVASIVE DETECTION OF TUMOR PROGRESSION IN GLIOBLASTOMA PATIENTS

INTRODUCTION Detection of tumor progression in glioblastoma patients remains a major challenge for clinicians due to equivocal MRI results. Extracellular vesicles (EVs) are potential biomarkers and can be detected in the blood of tumor patients. In this study, we evaluated the potential of serum-derived EVs from glioblastoma patients to serve as a marker for tumor progression in adjunction with MRI assessment. METHODS Glioblastoma patients from two independent cohorts, one from the multicenter Phase III CeTeG/NOA-09 trial (n=36) and the other from patients treated at the University of Bonn (n=31), were included in this study. EVs from serum of glioblastoma patients and healthy volunteers were separated by size exclusion chromatography and ultracentrifugation. EV markers were defined by using a proximity-extension assay and bead-based flow cytometry. Tumor progression was defined according to modified RANO criteria. RESULTS EVs from the serum of glioblastoma patients (n=67) showed an upregulation of CD29 (p=0.08), CD44 (p< 0.0001), CD81 (p< 0.0001), CD146 (p< 0.0001), C1QA (p=0.003), and histone H3 (p< 0.0001) as compared to serum EVs from healthy volunteers. For both independent cohorts of glioblastoma patients, we noted upregulation of C1QA, CD44, and histone H3 upon tumor progression, but not in patients with stable disease. Notably, six patients with worse survival compared to the median survival of the cohort did not fulfill RANO criteria at the time of suspected progression, yet showed an elevation of at least one out of these three markers. In a multivariable logistic regression analysis, a combination of CD29, CD44, CD81, C1QA, and histone H3 correlated with RANO-defined tumor progression with an AUC of 0.76. CONCLUSION Measurement of CD29, CD44, CD81, C1QA, and histone H3 in serum-derived EVs of glioblastoma patients, along with standard MRI assessment, could improve detection of true tumor progression and thus be a useful tool for clinical decision making.

CTNI-50. REGORAFENIB IN RECURRENT GLIOBLASTOMA PATIENTS: A LARGE REAL-LIFE EXPERIENCE

INTRODUCTION Regorafenib (REG), an oral multikinase inhibitor, showed benefit in recurrent GBM (recGBM) patients in the REGOMA trial. We investigated the clinical outcome and safety of REG in a real-life population of recGBM patients treated at Veneto Institute of Oncology as off-label use. MATERIAL AND METHODS Patients receiving REG were entered prospectively on a clinical database. Data were retrospectively analyzed. The primary endpoints were overall survival (OS) and safety. The major inclusion criteria were: histologically confirmed diagnosis of GBM, disease progression by RANO criteria after Stupp protocol, ECOG PS ≤ 2. Patients received REG 160 mg per day for the first 3 weeks in a 4-week cycle. Kaplan-Meier method was used to estimate the survival, RANO criteria for radiological assessment, CTCAE v5.0 for drug related adverse events. RESULTS 54 patients were enrolled: median age was 56, ECOG PS 0-1 in 91%, MGMTmet in 53%, second surgery at the time of relapse in 30%. Median follow-up was 11.1ms, 30 PTS (56%) had died and 50 PTS (93%) had progressed. MedianOS was 10.2 ms (95%CI, 6.4-13.9), 12m-OS was 43%; medianPFS was 2.3 ms (95%CI, 1.3-3.3) and 6m-PFS was 18%. Disease control rate (DCR) was 46.3%; stable disease was reported in 38.8% and partial response in 7.4%. Age, MGMT and corticosteroid use at baseline were not statistically significant on multivariate analysis for OS. Grade 3 drug-related adverse events (AEs) occurred in 10 patients (18%) and the most frequent were hand-foot skin reaction, asthenia and increased lipase and transaminases; 1 PT(2%) reported a grade 4 AE (rash maculo-papular). AEs led to REG dose reductions in 37% of patients and, it was permanently discontinued in 5%. CONCLUSIONS We reported a “real-world” experience of REG in recGBM patients. Results are close to those reported in REGOMA trial; we showed a longer OS. Toxicity was manageable. Encouraging clinical benefits of REG in recGBM population were confirmed.

NEIM-05. [GA68]DOTATATE PET/MRI-BASED RADIOSURGICAL RESPONSE ASESSMENT IN MENINGIOMA

PURPOSE Postoperative PET/MRI with [68Ga]-DOTATATE can differentiate residual meningioma from postsurgical change, aid in target delineation, and portend a more favorable dosimetry with decreased PTV and organ-at-risk dose. Our purpose was to demonstrate utility of DOTATATE PET/MR for radiosurgical treatment (RT) response assessment in meningiomas. METHODS Patients underwent postoperative radiation treatment planning using DOTATATE PET/MRI as part of our IRB-approved prospective trial. Both DOTATATE PET and gadolinium-enhanced T1 weighted MR imaging were incorporated in RT-planning. All patients underwent follow-up DOTATATE PET/MRI at 6-12 months following completion of radiosurgery. Maximum absolute standardized uptake value (SUV) and SUV ratio (SUVR) of lesion/ superior sagittal sinus SUV were obtained. RANO criteria were applied to determine significance of change in size. Statistical analyses were performed using paired t-tests. RESULTS 13 patients (15% WHO-I, 54% WHO-II, 23% WHO-III, 8% WHO grade unknown) were followed postoperatively with pre- and post-RT DOTATATE PET/MRI. 29 meningiomas were treated. 46% (6/13) of subjects received SBRT and 54% (7/13) received SRS. Post-RT DOTATATE PET/MRI demonstrated a 46.4% SUV decrease (p-value = 0.0001) and a 60.8% SUVR decrease (p-value < 0.0001). Of 21 measurable lesions, the size product decreased by 21%; while this decrease was statistically significant (p-value = 0.0008), it was below the 25% decrease defined as clinically significant by RANO guidelines. To date, all patients remain stable radiographically without evidence of recurrence (mean follow-up post RT: 14 months; range: 6-24 months). CONCLUSIONS DOTATATE PET SUV and SUVR demonstrated marked, significant decrease post radiosurgery. Lesion size decrease was statistically significant but not clinically significant by RANO criteria. DOTATATE PET/MR thus represents a promising approach to aid in response assessment for radiosurgically treated meningiomas. Longer-term follow-up is needed to determine the correlation between the degree of post-RT SUV and/or SUVR decrease and progression-free-survival.

KS02.4.A Olaparib in Recurrent IDH-mutant High-Grade Glioma (OLAGLI)

BACKGROUND There is a need to develop new treatments in IDH-mutant high-grade gliomas recurring after radiotherapy and chemotherapy. Based on preclinical studies showing that IDH-mutant tumors could be vulnerable to PARP inhibition we launched a phase II study to test the efficacy of olaparib (Lynparza) monotherapy in this population. METHODS Adults with recurrent high-grade IDH-mutant gliomas after radiotherapy and at least one line of alkylating chemotherapy (PCV or TMZ), KPS > 60, normal organ function were enrolled. The primary endpoint was 6 months PFS according to RANO criteria. Patients were treated with olaparib 300 mg twice daily. We used a single-stage Fleming design with p0 = 30%, p1 = 50%, a type I unilateral error rate of 5% and a power of 80%. RESULTS 35 patients with recurrent IDH-mutant gliomas (IDH1R132H-mutant n = 32, other IDH mutation n = 3, 1p/19 codeleted n = 16, 1p/19q non-codeleted n = 14) were enrolled (malignantly transformed low-grade gliomas n = 21, anaplastic gliomas n = 8, glioblastomas n = 6). Median time since diagnosis was 7.4 years (1–22 years), median time since radiotherapy was 2.8 years (0.6–18 years), median number of previous chemotherapy lines was 2 (1–5). With a median follow-up of 11 months, 30 patients had stopped treatment due to tumor progression and 2 patients were still on treatment 16 to 18 months after treatment start. At 6 months, 11/35 patients were progression-free (31 %). According to RANO criteria, based on local investigator analysis, 2 patients (5%) had a partial response and 14 patients a stable disease (37%) with a median duration of response of 9 months (4–18+). Median PFS and OS were 2.3 and 15.9 months and were similar in 1p/19q codeleted and non-codeleted patients. A grade 3 olaparib-related adverse event was observed in 5 patients (14%, lymphopenia n = 3, fatigue n = 2, diarrhea n = 1) and a grade 2 in 15 patients (43%), most frequently consisting in fatigue (23%), gastrointestinal disorders (20%) and lymphopenia (20%). No patient definitively stopped olaparib due to side effects. CONCLUSIONS In this heavily pre-treated population of recurrent IDH-mutant gliomas, olaparib monotherapy was well tolerated and resulted in some activity supporting its evaluation in association with alkylating chemotherapy in recurrent IDH-mutant gliomas in future studies.

P14.19 Regorafenib in recurrent glioblastoma patients: a large real-life experience

BACKGROUND Regorafenib (REG), an oral multikinase inhibitor of angiogenic, stromal, and oncogenic receptor tyrosine kinases showed encouraging benefit in recurrent GBM patients enrolled in the randomized, phase 2 REGOMA trial. We investigated the clinical outcome and safety of REG in a real-life population of recurrent glioblastoma patients treated at Veneto Institute of Oncology as off-label use. MATERIAL AND METHODS Patients receiving REG at Veneto Institute of Oncology (Padua, Italy) were entered prospectively on a clinical database. Data were retrospectively analyzed. The primary endpoints of the study were overall survival (OS) and safety. The major inclusion criteria were: histologically confirmed diagnosis of GBM, disease progression as defined by RANO criteria after surgery followed by radiochemotherapy with temozolomide, ECOG PS ≤ 2; PTS with ≥ 2 prior lines of therapy were excluded. According to original schedule, patients received REG 160 mg once daily for the first 3 weeks of each 4-week cycle until disease progression, death, unacceptable toxicity, or consent withdrawal. Kaplan-Meier method was used to estimate the survival curves, RANO criteria for radiological assessment, CTCAE v5.0 for drug related adverse events. RESULTS From February 2018 to September 2020, 54 consecutive patients were treated with REG and enrolled in this study: median age was 56, ECOG PS 0–1 in 91% of patients, MGMTmet in 53%, second surgery at the time of relapse were performed in 30% of enrolled patient, 41% of patients underwent steroids at baseline. At the time of analysis, median follow-up was 11.1 ms, 30 PTS (56%) had died and 50 PTS (93%) had progressed. Median OS was 10.2 ms (95%CI, 6.4–13.9), 12m-OS was 43%; median PFS was 2.3ms (95%CI, 1.3–3.3) and 6m-PFS was 18%. All patients were evaluable for response: disease control rate (DCR) was 46.3%; stable disease was reported in 38.8% and partial response in 7.4%. Age, MGMT status and corticosteroid use at baseline were not statistically significant on multivariate analysis for OS. Grade 3 drug-related adverse events (AEs) occurred in 10 patients (18%) and the most frequent were hand-foot skin reaction, asthenia and increased lipase and transaminases; 1 PT (2%) reported a grade 4 AE (rash maculo-papular). AEs led to REG dose reductions in 37% of patients and, it was permanently discontinued in 5%. No death was considered to be drug-related. CONCLUSION We reported a large, mono-institutional “real world” experience of REG in recurrent glioblastoma patients. Overall, results are close to those reported in REGOMA trial although, we showed a longer OS. Toxicity was moderate and manageable. Encouraging clinical benefits of REG in recurrent GBM population were confirmed.