The treatment outcomes and genomic profiles of diffuse midline glioma (DMG) in adult patients are rarely characterized. We performed a retrospective study to evaluate the clinicogenomic profiles of adult patients with brain DMG.
Patients aged ≥ 18 years diagnosed with brain DMG at Seoul National University Hospital were included. The clinicopathological parameters, treatment outcomes, survival, and genomic profiles using 82-gene targeted next-generation sequencing (NGS) were analyzed. The 6-month progression-free survival (PFS6) after radiotherapy and overall survival (OS) were evaluated.
Thirty-three patients with
PFS6 after radiotherapy was associated with prolonged survival in adult patients with DMG. Genome-based matched therapy may be an encouraging approach for progressive adult patients with DMG.
In the 2016 World Health Organization (WHO) classification, histone 3 (
DMGs are notable for harboring histone mutations, including
DMG is also found in adult patients with similar clinical features to those of pediatric patients [
We searched records for adult patients aged ≥ 18 years who were diagnosed with DMG involving the brain at Seoul National University Hospital between May 2005 and September 2019. DMG was defined as an infiltrative midline high-grade glioma with predominantly astrocytic differentiation and
Data including the patients’ demographics, radiographic findings, pathologic findings, diagnosis date, detailed treatments, initiation date of treatments, status of disease progression, and survival outcomes, were collected using the electronic medical records system.
The surgical extent of DMG was classified into four groups based on the following: gross total resection (GTR) as complete resection of the mass and no visualized enhanced signal intensity in contrast-enhanced brain magnetic resonance imaging (MRI) obtained within 48 hours after surgery; near-total resection visualized as thin enhanced signal intensity in contrast-enhanced brain MRI obtained within 48 hours after surgery; subtotal resection as grossly remained tumor or visualized nodular enhancement in contrast-enhanced brain MRI obtained within 48 hours; biopsy only as biopsy without intent to tumor resection. We additionally evaluated T2 fluid attenuated inversion recovery (FLAIR) images to determine if there were any possible findings of residual tumors that were not identified by contrast-enhanced images.
The protocol used for concurrent chemoradiotherapy (CCRT) with temozolomide (TMZ) was either a standard 6-week [
Thirteen patients with available targeted NGS results were included. Genomic DNA was extracted from formalin-fixed paraffin-embedded tissue and was fragmented using a Covaris sonicator (Covaris, Woburn, MA). Agilent’s SureSelectXT Custom protocol was used to construct libraries (Agilent Technology, Santa Clara, CA), and MiSeqDx or NextSeq 550Dx (Illumina Inc., San Diego, CA) was used for sequencing.
The produced sequencing data were analyzed using the SNUH First Panel Analysis Pipeline. We performed quality control of the FASTQ file and further analyzed only the data that passed the criteria. Pair-end alignment to the hg19 reference genome was performed using BWA-men (v0.7.17) and GATK Best Practice [
After finishing the alignment step, an “analysis-ready BAM” was produced, and variants such as single-nucleotide variant (SNV), InDel, copy number variation (CNV), and translocation were detected using at least more than two analysis tools, including SNUH in-house and open-source software. GATK UnifiedGenotyper (v4.0.6.0), SNVer (v0.5.3), and LoFreq (v2.1.0) were used for SNV/InDel detection [
From those, we retained the variants meeting the following requirements: variant allele frequency ≥ 5%, reads supporting for alternative allele ≥ 10, reads supporting for alternative allele ≥ 10, and reads supporting each strand for alternative allele > 5 for SNV/InDel; copy number ≥ 6 and copy number ≤ 1 for CNV; split-reads supporting for alternative allele ≥ 10 for translocation. Other filtering criteria were applied using the default parameters of the analysis tools.
The detected variants were annotated by SnpEff (v4.3) using various databases such as RefSeq, COSMIC (v84), dbSNP (build 150), ClinVar (2018-06), and gnomAD (v2.0.1). The germline variant was filtered using the population frequency of these databases (> 1% population frequency) [
Descriptive statistics were mainly used to demonstrate the results in this study. To describe and compare the survival outcome, Kaplan-Meier survival curves and log-rank survival analysis were used. Cox proportional hazard model for univariate analysis was used to determine clinical factors associated with OS in patients who received radiotherapy. Next, Cox proportional hazard model for multivariate analysis was used with age, gender and the factors with p-values less than 0.2. Logistic regression analysis was performed to evaluate whether a genomic alteration identified at least two samples by NGS affects PFS6 in patients who received CCRT. Ninety-five percent confidence intervals (CI) were calculated for survival analyses. Fisher exact test was used to compare categorical values. p-values less than 0.05 were considered as statistically significant. All statistical analyses were performed using R software ver. 3.5.1 (
The demographics and histologic findings of patients with DMG are summarized in
IHC detected
Thirteen patients had available targeted NGS data with a median tumor fraction of 85% (range, 20% to 90%) and a median average read depth of 1,016.3 (range, 649.7 to 2,066.5). All patients had
One patient (DMG31) had paired targeted NGS data at the times of the first resection and re-surgery for relapsed tumor after adjuvant
Comparisons with published mutational profiles are summarized in
The median OS from diagnosis was 21.8 months (95% CI, 13.2 to NA) (
Fourteen patients (42.4%) underwent surgical resection of tumors for initial treatment. While only three of 14 patients (21.4%) with ponto-medullary involvement underwent surgical resection, 11 of 19 patients (57.9%) without ponto-medullary involvement underwent surgical resection including three GTR cases. Surgical resection was not associated with prolonged OS in all patients (median OS, 21.9 months [95% CI, 13.2 to NA] for the resected group vs. 20.4 months [95% CI, 11.9 to NA] for the unresected group; p=0.84) (
Twenty-four patients received radiotherapy: 20 and four patients received CCRT with TMZ and radiotherapy alone, respectively. Except for three patients who had received adjuvant chemoradiotherapy after GTR, the objective response rate of radiotherapy was 28.6% (n=6). The median PFS was 9.7 months (95% CI, 8.4 to 15.8), and the median OS was 24.9 months (95% CI, 18.2 to NA). The PFS6 rate was 83.3% (n=20; 95% CI, 69.7 to 99.7), and those without progression at 6 months showed significantly prolonged OS compared with the other four patients with progression at 6 months (median OS, 24.9 months [95% CI, 20.4 to NA] vs. 10.8 months [95% CI, 4.0 to NA]; p=0.02) (
Eleven patients had received salvage systemic therapies. The median OS from the initiation of systemic therapy was 8.3 months (95% CI, 6.1 to NA) in these patients. Six of these patients had surgical resection, and GTR was achieved in two patients. Bevacizumab was administered in seven patients as first-line salvage therapy after CCRT with TMZ, three of whom received irinotecan as combination.
The objective response rate, median PFS, and median OS after bevacizumab-based regimen were 28.6%, 1.6 months (95% CI, 1.4 to NA) (
Two patients received matched therapies in clinical trials: patient DMG14 with concurrent
Despite growing attention concerning pediatric DMG in various studies, the data on adult patients with DMG are only described in few studies [
As a driver mutation for glioblastoma,
We failed to demonstrate the prognostic significance of genomic profiles such as
The clinical outcomes of our adult patients with DMG were compared with those of two previous studies of adult patients with DMG (
Although patients who received palliative systemic treatments had a median OS of 8.3 months, a few responders seemed to have a prolonged OS. Additionally, two of 13 patients who had targeted NGS received matched therapies, including pan-RAF plus MEK inhibitors to target
The limitations of our retrospective study include the small number of patients with adult DMG as well as limited number of targeted NGS. Therefore, genomic demographics and their clinical associations are not fully elucidated in this study. In addition, there seemed modest benefits of matched investigational drugs in two patients.
In conclusion, our study demonstrated that a progression-free survival at 6 months after radiotherapy significantly improved survival in adult patients with DMG while surgical extent did not improve survival, suggesting the important role of radiotherapy in patients with adult brain DMG. Additionally, targeted sequencing revealed a high frequency of concurrent
Supplementary materials are available at Cancer Research and Treatment website (
All of data collection and analysis were performed after approval from the institutional review board (IRB No. 1811-054-983) in accordance with the declaration of Helsinki. The written informed consent was waived in this retrospective study.
Conceived and designed the analysis: Park C, Kim TM.
Collected the data: Park C, Kim TM, Bae JM, Yun H, Kim JW, Choi SH, Lee ST, Lee JH, Park SH, Park CK.
Contributed data or analysis tools: Park C, Kim TM, Bae JM, Yun H, Kim JW, Choi SH, Lee ST, Lee JH, Park SH, Park CK.
Performed the analysis: Park C, Kim TM, Yun H.
Wrote the paper: Park C, Kim TM, Bae JM, Yun H, Kim JW, Choi SH, Lee ST, Lee JH, Park SH, Park CK.
Dr. Tae Min Kim received grants from AstraZeneca-KHIDI outside this work. The other authors declare no potential conflicts of interest.
This study was supported by a grant from the Korean Health Technology R&D Project “Strategic Center of Cell and Bio Therapy for Heart, Diabetes & Cancer” through the Korea Health Industry Development Institute (KHIDI) funded by the Ministry of Health & Welfare (MHW) (grant number: HI-17C-2085, T.M.K.).
We thank Juyoun Kim who managed the database, the neuro-oncology multidisciplinary team at SNUH, and patients and their families.
Genomic landscape of adult patients with DMG obtained by targeted NGS. The landscape plot shows the genomic landscape of adult patients with DMG obtained by targeted NGS. The annotations with corresponding colors are described at the bottom. At the top of the plot, the bar plot shows the PFS of CCRT with TMZ of each patient with a cross mark depicting events. The dashed line crosses y-axis at 6 months. Below the bar plot is a tile plot that depicts the clinical features of each patient. The numbers at the bottom of the plots are the index numbers of the patients. Paired NGS samples at the time of diagnosis and progression after CCRT with TMZ were obtained from patient DMG31 (samples DMG31 and DMG31-1). CCRT, concurrent chemoradiotherapy; DMG, diffuse midline glioma; GTR, gross total resection; MAPK, mitogen-activated protein kinase; NGS, next-generation sequencing; NTR, near-total resection; PFS, progression-free survival; PFS6, 6-month progression-free survival; PI3K, phosphatidylinositol-3 kinase; RTK, receptor tyrosine kinase; STR, subtotal resection; TMZ, temozolomide.
Kaplan-Meier curves for the OS from diagnosis of all patients with DMG patients included in the study. (A) The Kaplan-Meier curve shows the overall survival of all patients with DMG. (B) The Kaplan-Meier curves show the overall survival of all patients with DMG according to ponto-medullary involvement. The blue line represents patients without ponto-medullary involvement; the red line represents patients with ponto-medullary involvement. The risk tables are below each plot, and p-values by the log-rank test are annotated in each plot. Censored data are depicted by vertical marks. DMG, diffuse midline glioma; OS, overall survival.
Kaplan-Meier survival curves for the OS from diagnosis of patients according to PFS6 status from radiotherapy. The Kaplan-Meier curves show the OS from diagnosis of patients who received radiotherapy. The blue line represents patients without progression at 6 months after radiotherapy initiation; the red line represents patients whose diseases had progressed at 6 months. The risk tables are below each plot, and p-values by the log-rank test are annotated in each plot. Censored data are depicted by vertical marks. OS, overall survival; PFS6, 6-month progression-free survival.
History and images of patient DMG14 with
Patient demographics
Characteristic | No. (%) (n=33) |
---|---|
39 (20–70) | |
Male | 17 (51.5) |
Female | 16 (48.5) |
Dizziness | 9 (27.3) |
Memory impairment | 9 (27.3) |
Headache | 8 (24.2) |
Diplopia | 6 (18.2) |
Gait abnormality | 5 (15.2) |
Abnormal odor sensation | 3 (9.1) |
Dysarthria | 3 (9.1) |
Motor weakness | 3 (9.1) |
Visual field defect | 3 (9.1) |
Others |
10 (30.3) |
Yes | 14 (42.4) |
No | 19 (57.6) |
100 | 3 (9.1) |
80–90 | 16 (48.5) |
50–70 | 10 (30.3) |
Biopsy only | 19 (57.6) |
Subtotal resection | 8 (24.2) |
Near-total resection | 3 (9.1) |
Gross total resection | 3 (9.1) |
CCRT with TMZ | 20 (60.1) |
Radiotherapy alone | 4 (12.1) |
Gamma-knife surgery | 1 (3.0) |
Surgery | 4 (12.1) |
Gamma-knife surgery | 1 (3.0) |
Systemic chemotherapy | 11 (33.3) |
Radiotherapy | 2 (6.1) |
CCRT | 1 (3.0) |
10 (32.2) | |
1 (3.0) | |
6 (26.1) | |
8 (34.8) | |
1 (3.0) |
CCRT, concurrent chemoradiotherapy; KPS, Karnofsky performance status; TMZ, temozolomide.
Other initial symptoms include facial palsy (n=2), loss of consciousness (n=2), swallowing abnormality (n=2), sensory abnormality (n=2), dysphasia (n=1), and tinnitus (n=1).
Mutational profiles of adult patients with DMG
Targeted NGS results of this study (n=13) | Schwartzentruber et al. [ |
Mackay et al. [ |
Nikbakht et al. [ |
Aihara et al. [ | |
---|---|---|---|---|---|
Population | Adult | Pediatric | Pediatric | Pediatric | Adult |
2 (15.4) | 9 (60.0) | 46 (23.0) | 3 (33.3) | 2 (28.6) | |
1 (7.7) | 0 | 28 (14.0) | 3 (33.3) | NA | |
1 (7.7) | 0 | 1 (0.5) | NA | 0 | |
2 (23.1) | 3 (20.0) | 11 (5.5) | NA | 3 (42.9) | |
0 | 3 (20.0) | 21 (10.5) | 0 | 0 | |
2 (15.4) | 0 | 23 (11.5) | 3 (33.3) | 0 | |
9 (69.2) | 12 (80.0) | 126 (63.0) | 5 (55.6) | 2 (28.6) |
Values are presented as number (%). DMG, diffuse midline glioma; NA, not available; NGS, next-generation sequencing.
Comparisons of adult patients with DMG with those in previous studies
This study (n=33) | Meyronet et al. [ |
Schreck et al. [ | |
---|---|---|---|
Age (yr) | 20–70 | 18–82 | 30–68 |
1 (3.0) | 0 | 0 | |
1 (3.0) | 1 (4.8) | 1 (5.6) | |
Resection rate (GTR rate) (%) | 42.4 (9.1) | 19.0 (NA) | 28 (6) |
Patients who received CCRT or RT (%) | 72.7 | 66.7 | 65.0 |
ORR (%) | 27.2 | NA | NA |
Median OS from diagnosis in all patients (mo) | 21.8 | 19.6 | 17.6 |
Median OS from diagnosis in patients who received CCRT or RT (mo) | 24.9 | 25.0 | NA |
CCRT, concurrent chemoradiotherapy; DMG, diffuse midline glioma; GTR, gross total resection; IDH, isocitrate dehydrogenase; MGMT, O6-methylguanine-DNA methyltransferase; NA, not available; ORR, overall response rate; OS, overall survival; RT, radiotherapy.