BIOM-28. SERIAL PLASMA AND CSF CELL-FREE TUMOR DNA (cf-tDNA) TRACKING IN DIFFUSE MIDLINE GLIOMA PATIENTS UNDERGOING TREATMENT WITH ONC201

Diffuse midline glioma (DMG) with H3K27M mutation is a lethal childhood brain cancer, with limited means of monitoring beyond serial MRI scans. We conducted a multi-site Phase 1 trial of the imipridone ONC201 for children with H3K27M-mutant glioma (NCT03416530). Patients on Arm D of the trial (n=24) underwent serial lumbar puncture (baseline, 2 and 6-months) for cell-free tumor DNA (cf-tDNA) analysis at time of MRI. Additionally, patients on all arms of the trial at the University of Michigan underwent serial plasma collection. We collected a total of 96 plasma-samples and 53 CSF-samples from 29 patients. We performed ddPCR analysis of cf-tDNA samples and compared variant allele fraction (VAF) to radiographic change (maximal tumor area on MRI). For our H3F3A-mutated (K27M) patients, cf-tDNA was positive in 53/62 plasma samples (sensitivity 85.4%) and 28/29 CSF samples (sensitivity 96.5%) and overall specificity of 100%. There was no direct correlation between percent-change in tumor-area and plasma (p=0.47) or CSF VAF (p=0.89), implying that VAF provided information supplemental to radiographic assessments. “Spikes” in plasma cf-tDNA VAF (increase of ≥25%) co-occurred with progression in 2/9 (22%) cases and preceded progression in 5/9 cases (55%) by an average of 1.22 months. In CSF, spikes preceded progression in 4/6 cases (66%) by an average of 1.8 months. Two patients had increases in tumor-area with no increase in plasma VAF; both were later confirmed as pseudo-progressors, suggesting additional potential utility of cf-tDNA VAF monitoring. A 14yo male with spinal cord glioma received concurrent bevacizumab with ONC201, which resulted in a decrease in tumor area but continued increase in plasma VAF, predicting radiologic progression at the next time. In summary, we present data which suggests monitoring serial CSF/plasma H3K27M tDNA is a promising clinical tool. Changes in cf-tDNAVAF over time appear to correlate with response, predict progression, and differentiate pseudo-progression.

Chemotherapy for adult patients with spinal cord gliomas

Background The incidence of spinal cord gliomas, particularly in adults is low, and the role of chemotherapy has remained unclear. Methods We performed a multicenter, retrospective study of 21 patients diagnosed with spinal cord glioma who received chemotherapy at any time during the disease course. Benefit from chemotherapy was estimated by magnetic resonance imaging. Data on radiotherapy were taken into consideration. Results Thirteen patients were diagnosed with astrocytic gliomas World Health Organization (WHO) grades 1-4, the remaining eight patients with ependymomas WHO grades 1 or 3. Most patients had more than one neurosurgical intervention. Median age at time of first chemotherapy was 33 years (range 21-67 years). Seven patients had chemotherapy combined with radiotherapy as first-line treatment. Two patients had chemoradiotherapy at recurrence, without prior tumor-specific treatment beyond surgery. One patient received chemotherapy alone as first-line treatment and 2 patients had chemotherapy alone at recurrence, without prior treatment. Nine patients had received radiation therapy at an earlier time and chemotherapy was given at time of further recurrences. Best responses in astrocytomas were as follows: chemotherapy alone – 2 stable disease (SD), 3 progressive disease (PD); chemoradiotherapy – one complete response, 3 SD, 4 PD. Best responses in ependymomas were as follows: chemotherapy alone – one partial response, 5 SD, one PD; chemoradiotherapy – one SD. Conclusions Spinal cord gliomas represent a heterogeneous group of tumors. Survival outcomes in response to chemotherapy in adult spinal cord glioma patients vary substantially, but individual patients appear to derive benefit from chemotherapy.

Application evaluation of intraoperative ultrasound combined with neuro electrophysiological detection in the spinal cord glioma surgery

Objective: To observe application values of intraoperative ultrasound combined with neuro electrophysiological detection in the spinal cord glioma surgery. Methods: Sixty patients with spinal cord glioma hospitalized in Baoding First Central Hospital from January 2016 to January 2018 were selected, randomly divided into two groups by the random number table method, with 30 cases of each group. PASS software was used to calculate the sample size. The control group was treated with traditional microsurgery, while the experimental group was treated with intraoperative ultrasound combined with neuro electrophysiological testing. The operation time, intraoperative blood loss, postoperative hospital stays, degree of tumor resection, clinical efficacy, recovery of neurological function, recovery of health status, quality of life score, and 2-year recurrence rate of the two groups of patients were observed and compared. Results: The operation time of the experimental group was longer than that of the control group, and the postoperative hospital stay was shorter than that of the control group. The complete tumor resection rate, complete remission rate and postoperative scale scores of the experimental group were significantly higher than those of the control group, while the recurrence rate within two years was significantly lower than that of the control group. The above differences were statistically significant (p<0.05). Conclusions: Intraoperative ultrasound combined with neuro-electrophysiological detection for spinal glioma has more adequate protection of nerve function, high clinical complete remission rate, more thorough tumor resection, and lower recurrence rate than traditional microsurgery, which is worthy of clinical application. doi: https://doi.org/10.12669/pjms.37.3.3638 How to cite this:Li X, Liu ZJ, Liang L, Dong HQ. Application evaluation of intraoperative ultrasound combined with neuro electrophysiological detection in the spinal cord glioma surgery. Pak J Med Sci. 2021;37(3):---------. doi: https://doi.org/10.12669/pjms.37.3.3638 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

HGG-50. TWO CASES OF H3 K27M-MUTANT DIFFUSE MIDLINE GLIOMA OF CERVICAL SPINAL CORD

BACKGROUND “Diffuse midline glioma, H3 K27M-mutant’ was newly categorized as a separate pathological entity in the 2016 WHO classification, based on recently discovered mutation. Spinal cord glioma with H3 K27M-mutant is rare, so we reported the clinical course of two cases. CASE 1: A 17-year-old male presented with posterior headache and right limbs paralysis. MRI showed cervical spinal cord with expansion, T2-weighted high intensity and a part of enhancement. The biopsy revealed a diffuse midline glioma, H3 K27M-mutant. He received bevacizumab plus radiotherapy-temozolomide. In a few months, he had quadriplegia and cranial nerve paralysis and needed respirator. There was not expansion of mass, but intracranial dissemination. CASE 2: A 16-year-old male presented with posterior neck pain and right limbs paralysis. On brain stem and cervical spine, MRI findings were same to case 1. The biopsy was undergone and revealed H3 K27M mutation. He received bevacizumab in addition to radiotherapy-temozolomide. Although he also had quadriplegia, the progression of tumor has stopped. He has received chemotherapy with respirator at home. DISCUSSION It was previously reported that the prognostic factors for diffuse midline glioma were tumor location, H3 K27M-mutation and age, but there are few relevant studies. The consensus on the treatment is also not clearly determined. Because the cervical spinal cord gliomas are rapidly advanced miserably, we added bevacizumab to standard radiotherapy-temozolomide for initial treatment. In addition, whole brain and spine radiation may be considered to avoid dissemination. Multicenter study is important to collect information and improve treatment of H3 K27M-mutant glioma.