Somatostatin receptor subtype expression and radiomics from DWI-MRI represent SUV of [68Ga]Ga-DOTATOC PET in patients with meningioma

OBJECTIVE

This retrospective study aimed to analyse the correlation between somatostatin receptor subtypes (SSTR 1-5) and maximum standardized uptake value (SUVmax) in meningioma patients using Gallium-68 DOTA-D-Phe1-Tyr3-octreotide Positron Emission Tomography ([68Ga]Ga-DOTATOC PET). Secondly, we developed a radiomic model based on apparent diffusion coefficient (ADC) maps derived from diffusion weighted magnetic resonance images (DWI MRI) to reproduce SUVmax.

METHOD

The study included 51 patients who underwent MRI and [68Ga]Ga-DOTATOC PET before meningioma surgery. SUVmax values were quantified from PET images and tumour areas were segmented on post-contrast T1-weighted MRI and mapped to ADC maps. A total of 1940 radiomic features were extracted from the tumour area on each ADC map. A random forest regression model was trained to predict SUVmax and the model's performance was evaluated using repeated nested cross-validation. The expression of SSTR subtypes was quantified in 18 surgical specimens and compared to SUVmax values.

RESULTS

The random forest regression model successfully predicted SUVmax values with a significant correlation observed in all 100 repeats (p < 0.05). The mean Pearson's r was 0.42 ± 0.07 SD, and the root mean square error (RMSE) was 28.46 ± 0.16. SSTR subtypes 2A, 2B, and 5 showed significant correlations with SUVmax values (p < 0.001, R2 = 0.669; p = 0.001, R2 = 0.393; and p = 0.012, R2 = 0.235, respectively).

CONCLUSION

SSTR subtypes 2A, 2B, and 5 correlated significantly with SUVmax in meningioma patients. The developed radiomic model based on ADC maps effectively reproduces SUVmax using [68Ga]Ga-DOTATOC PET.

Whole brain radiotherapy combined with intrathecal liposomal cytarabine for leptomeningeal metastasis-a safety analysis and validation of the EANO-ESMO classification

BACKGROUND

Although there is no proven standard therapy for leptomeningeal metastases (LM), treatment often includes intrathecal chemotherapy combined with whole brain radiation therapy (WBRT). Little is known about the toxicity of such combination therapies. We performed a retrospective safety analysis for the combination of intrathecal liposomal cytarabine with WBRT in patients with LM and validated the EANO-ESMO (European Association of Neuro-oncology-European Society for Medical Oncology) classification in this unique cohort.

METHODS

Treatment toxicities in patients diagnosed with LM between 2004 and 2014 were retrospectively analyzed according to RTOG (Radiation Therapy Oncology Group) toxicity criteria and NCI CTCAE V5.0 (National Cancer Institute Common Terminology Criteria for Adverse Events, Version 5.0). Diagnostic criteria and treatment response as assessed by EANO-ESMO classification were correlated with survival by Kaplan-Meier analysis and Breslow test.

RESULTS

In all, 40 patients with LM who were treated with combined WBRT and intrathecal cytarabine, were identified. Ten patients (25%) experienced adverse events ≥grade 3 according to RTOG toxicity criteria; in 22 patients (55%) NCI CTCAE ≥grade 3 were detected. Median overall survival was 124 days. Median time to neurological progression was 52 days. Patients with positive cerebrospinal fluid (CSF) cytology (n = 26) showed worse prognosis compared to patients with negative CSF cytology (n = 14; mOS (median overall survival) 84 days versus 198 days, p = 0.006, respectively). The EANO-ESMO response assessment was significantly associated with survival: "stable" (n = 7) mOS 233 days, "response" (n = 10) mOS 206 days, "progression" (n = 17) mOS 45 days, "suspicion of progression" (n = 6) mOS 133 days; overall, p < 0.001.

CONCLUSIONS

In this retrospective analysis, combined treatment of WBRT and intrathecal liposomal cytarabine shows an acceptable safety profile and may indicate a trend towards improved efficacy. The EANO-ESMO classification for diagnosis and treatment response predicts survival.

NCMP-14. WHOLE BRAIN RADIOTHERAPY COMBINED WITH INTRATHECAL LIPOSOMAL CYTARABINE FOR LEPTOMENINGEAL METASTASIS – A SAFETY ANALYSIS AND VALIDATION OF THE EANO-ESMO CLASSIFICATION

BACKGROUND

Although there is no proven standard therapy for leptomeningeal metastases (LM), treatment often includes intrathecal chemotherapy combined with whole brain radiation therapy (WBRT). Little is known on the toxicity of such combination therapies. We performed a retrospective safety analysis for the combination of intrathecal liposomal cytarabine with WBRT in patients with LM and validated the EANO-ESMO classification in this unique cohort.

METHODS

Treatment toxicities in patients diagnosed with LM between 2004 and 2014 were retrospectively analyzed according to the RTOG (Radiation Therapy Oncology Group) and NCI CTCAE V5.0 (Common Toxicity Criteria Adverse Events) toxicity criteria. Diagnostic criteria and treatment response as assessed by EANO-ESMO classification were correlated with survival by Kaplan Meier analysis and Breslow test.

RESULTS

40 patients with LM who were treated with combined WBRT and intrathecal cytarabine, were identified. Ten patients (25%) experienced adverse events ≥ grade 3 according to the RTOG-toxicity criteria, in 22 patients (55%) CTCAE criteria ≥3 grade were detected. Median overall survival (mOS) was 124.0 days [72.9;175.1]. Median time to neurological progression was 52.0 days [41.1; 62.8]. When comparing the diagnostic criteria, patients with a positive CSF cytology (n=26) showed worse prognosis compared to patients with a negative CSF cytology (n=14) (mOS 84 days [44.0;124.0] versus 198.0 days [162.6;233.4] days, p=0.006, respectively). The EANO-ESMO response assessment correlated significantly with survival - “stable” (n=7) mOS 233.0 [76.5;389.5] days, “response” (n=10) mOS 206.0 [193.9;218.9] days, “progression” (n=17) mOS 45.0 [34.4;55.6] days, “suspicion of progression” (n=6) mOS 133.0 [65.8;200.2] days (overall, p&lt; 0.001).

CONCLUSIONS

In this retrospective analysis, the treatment combination of WBRT and intrathecal liposomal cytarabine shows an acceptable safety profile. The EANO-ESMO classification for diagnosis and treatment response predicts survival

NIMG-13. RESPONSE ASSESSMENT IN GLIOBLASTOMA PATIENTS TREATED WITH DENDRITIC CELL-BASED IMMUNOTHERAPY: A COMPARATIVE ANALYSIS OF MACDONALD, RANO, MRANO, IRANO AND VOLUMETRIC MEASUREMENTS

INTRODUCTION

Response assessment in the treatment of glioblastoma (GB) based on MR-imaging is still challenging, in particular for immunotherapeutic strategies. Several assessment tools have been proposed. In this post-hoc analysis we compared response assessment criteria (MacDonald, RANO, mRANO, Vol.-mRANO, iRANO) in newly diagnosed GB patients treated with tumor lysate-charged autologous dendritic cells (Audencel) and determined the differences in prediction of progression free survival (PFS) and overall survival (OS).

METHODS

76 patients with newly diagnosed GB enrolled in a multicenter randomized phase II trial receiving standard of care (SOC, n= 40) or SOC + Audencel vaccine (n= 36) were included. Tumor volumes were calculated by semiautomatic segmentation. To detect differences in PFS among the assessment criteria Kruskal-Wallis-test, for correlation analysis Spearman test was used.

RESULTS

There was a significant difference in median PFS based on the different assessments (mRANO 8.55 months [9.10-14.03], Vol.-mRANO 8.61 months [9.72-14.92] compared to MacDonald 4.04 months [5.21-8.75] and RANO 4.16 months [5.28-8.61]. For the vaccination arm only, median PFS by iRANO was 5.95 months [5.70-11.54]). There was no difference in PFS between SOC and SOC + Audencel using the different response criteria. The best correlation between PFS and OS was detected for mRANO (r= 0.65, p&lt; 0.001) and Vol.-mRANO (r= 0.69, p&lt; 0.001). At an 8-month landmark, the impact of progressive disease on median OS was best shown for mRANO (13.70 months [13.13-18.98], and Vol.-mRANO 12.03 months [12.51-17.94]) compared to MacDonald 17.97 months [15.45-20.92], RANO 17.97 months [15.92-20.95] and iRANO 17.34 months [14.99-22.73].

CONCLUSION

When comparing different response assessments in GB patients treated with dendritic cell-based immunotherapy the best correlation between PFS and OS was observed for mRANO and Vol.-mRANO. Overall, no difference in PFS and OS was seen between the two treatment arms. iRANO was not superior for predicting OS in patients treated with Audencel.