Risk prediction in early childhood sonic hedgehog medulloblastoma treated with radiation-avoiding chemotherapy: Evidence for more than 2 subgroups

BACKGROUND

The prognostic impact of clinical risk factors and DNA methylation patterns in sonic hedgehog (SHH)-activated early childhood desmoplastic/nodular medulloblastoma (DMB) or medulloblastoma with extensive nodularity (MBEN) were evaluated to better identify patients at risk for relapse.

METHODS

One hundred and forty-four patients with DMB (n = 99) or MBEN (n = 45) aged <5 years and treated with radiation-sparing approaches, including intraventricular methotrexate in 132 patients were evaluated.

RESULTS

Patients with DMB had less favorable 5-year progression-free survival than MBEN (5y-PFS, 71% [DMB] vs. 93% [MBEN]). Patients aged >3 years were associated with more unfavorable 5y-PFS (47% [>3 years] vs. 85% [<1 year] vs. 84% [1-3 years]). DNA methylation profiles available (n = 78) were reclassified according to the 2021 WHO classification into SHH-1 (n = 39), SHH-2 (n = 38), and SHH-3 (n = 1). Hierarchical clustering delineated 2 subgroups among SHH-2: SHH-2a (n = 19) and SHH-2b (n = 19). Patients with SHH-2b medulloblastoma were older, predominantly displayed DMB histology, and were more often located in the cerebellar hemispheres. Chromosome 9q losses were more frequent in SHH-2b, while few chromosomal alterations were observed in SHH-2a. SHH-2b medulloblastoma carried a significantly increased relapse risk (5y-PFS: 58% [SHH-2b] vs. 83% [SHH-1] vs. 95% [SHH-2a]). Subclassification of SHH-2 with key clinical and cytogenetic characteristics was confirmed using 2 independent cohorts (total n = 188). Gene mutation analysis revealed a correlation of SHH-2a with SMO mutations.

CONCLUSIONS

These data suggest further heterogeneity within early childhood SHH-DMB/MBEN: SHH-2 splits into a very low-risk group SHH-2a enriched for MBEN histology and SMO mutations, and SHH-2b comprising older DMB patients with a higher risk of relapse.

Transcriptome analysis stratifies second-generation non-WNT/non-SHH medulloblastoma subgroups into clinically tractable subtypes

Medulloblastoma (MB), one of the most common malignant pediatric brain tumor, is a heterogenous disease comprised of four distinct molecular groups (WNT, SHH, Group 3, Group 4). Each of these groups can be further subdivided into second-generation MB (SGS MB) molecular subgroups, each with distinct genetic and clinical characteristics. For instance, non-WNT/non-SHH MB (Group 3/4) can be subdivided molecularly into eight distinct and clinically relevant tumor subgroups. A further molecular stratification/summarization of these SGS MB would allow for the assignment of patients to risk-associated treatment protocols. Here, we performed DNA- and RNA-based analysis of 574 non-WNT/non-SHH MB and analyzed the clinical significance of various molecular patterns within the entire cohort and the eight SGS MB, with the aim to develop an optimal risk stratification of these tumors. Multigene analysis disclosed several survival-associated genes highly specific for each molecular subgroup within this non-WNT/non-SHH MB cohort with minimal inter-subgroup overlap. These subgroup-specific and prognostically relevant genes were associated with pathways that could underlie SGS MB clinical-molecular diversity and tumor-driving mechanisms. By combining survival-associated genes within each SGS MB, distinct metagene sets being appropriate for their optimal risk stratification were identified. Defined subgroup-specific metagene sets were independent variables in the multivariate models generated for each SGS MB and their prognostic value was confirmed in a completely non-overlapping validation cohort of non-WNT/non-SHH MB (n = 377). In summary, the current results indicate that the integration of transcriptome data in risk stratification models may improve outcome prediction for each non-WNT/non-SHH SGS MB. Identified subgroup-specific gene expression signatures could be relevant for clinical implementation and survival-associated metagene sets could be adopted for further SGS MB risk stratification. Future studies should aim at validating the prognostic role of these transcriptome-based SGS MB subtypes in prospective clinical trials.

Outcomes of Infants and Young Children With Relapsed Medulloblastoma After Initial Craniospinal Irradiation-Sparing Approaches: An International Cohort Study

PURPOSE

Infant and young childhood medulloblastoma (iMB) is usually treated without craniospinal irradiation (CSI) to avoid neurocognitive late effects. Unfortunately, many children relapse. The purpose of this study was to assess salvage strategies and prognostic features of patients with iMB who relapse after CSI-sparing therapy.

METHODS

We assembled a large international cohort of 380 patients with relapsed iMB, age younger than 6 years, and initially treated without CSI. Univariable and multivariable Cox models of postrelapse survival (PRS) were conducted for those treated with curative intent using propensity score analyses to account for confounding factors.

RESULTS

The 3-year PRS, for 294 patients treated with curative intent, was 52.4% (95% CI, 46.4 to 58.3) with a median time to relapse from diagnosis of 11 months. Molecular subgrouping was available for 150 patients treated with curative intent, and 3-year PRS for sonic hedgehog (SHH), group 4, and group 3 were 60%, 84%, and 18% (P = .0187), respectively. In multivariable analysis, localized relapse (P = .0073), SHH molecular subgroup (P = .0103), CSI use after relapse (P = .0161), and age ≥ 36 months at initial diagnosis (P = .0494) were associated with improved survival. Most patients (73%) received salvage CSI, and although salvage chemotherapy was not significant in multivariable analysis, its use might be beneficial for a subset of children receiving salvage CSI < 35 Gy (P = .007).

CONCLUSION

A substantial proportion of patients with relapsed iMB are salvaged after initial CSI-sparing approaches. Patients with SHH subgroup, localized relapse, older age at initial diagnosis, and those receiving salvage CSI show improved PRS. Future prospective studies should investigate optimal CSI doses and the role of salvage chemotherapy in this population.

EPEN-19. Impact of molecular classification on prognosis in children and adolescents with spinal ependymoma: Results from the HIT-MED database

PURPOSE: Ependymomas of the spinal cord are rare among children, and individual risks of disease progression are difficult to predict. This study aims at evaluating the prognostic impact of DNA methylation-based classification in children with spinal ependymoma. METHODS: Eighty-two patients with spinal ependymoma &lt;22 years registered in the HIT-MED database between 1992 and 2021 were included. Clinical, radiological, and histopathological data were collected retrospectively. DNA methylation profiles of 46 tumors were classified according to the Heidelberg Brain Tumor Classifier. RESULTS: Spinal myxopapillary ependymoma (SP-MPE, n=27) was the most common methylation group followed by spinal ependymoma (SP-EPN, n=15). Two cases belonged to MYCN-amplified subgroup, one had no match, and one was re-classified as anaplastic pilocytic astrocytoma (the latter excluded from final analysis). WHO grade I and III ependymomas (according to the WHO 2016 classification) classified predominantly as SP-MPE, whereas grade II ependymomas clustered into SP-MPE and SP-EPN. 6/15 patients with SP-EPN (40%) suffered from Neurofibromatosis type 2. Among patients with SP-MPE, 23 underwent gross-total and four a subtotal resection (GTR/STR). Relapses of SP-MPE were more common following STR (5-year progression-free survival (5y-PFS) [STR] 25.0% [95% confidence interval: 0.0-68.4], [GTR] 75.0% [53.4-96.6], p=0.003). In the SP-EPN group, 2/8 patients relapsed after STR (5y-PFS 64.3% [22,3-100]) and 0/7 after GTR (n.s.). WHO I° ependymoma had significantly inferior PFS than II° and III° ependymoma (5y-PFS [I°] 39.0% [5.8-62.2], [II°] 82.4% [67.8-97.0], [III°] 50.5% [18.9-82.1], p=0.009). However, PFS did not significantly differ between SP-MPE and SP-EPN (5y-PFS 65.9% [44.9-86.9], 76.9% [46.3-100], respectively). CONCLUSION: Spinal ependymomas of WHO grade I go along with relatively poor PFS in our cohort, while DNA methylation profiling does not segregate patients into distinct risk groups. Still, larger cohorts and further investigations of methylation class heterogeneity in pediatric spinal ependymomas are needed to complete the basis for future clinical decision-making.

MEDB-41. Identifying a subgroup of patients with early childhood sonic hedgehog-activated medulloblastoma with unfavorable prognosis after treatment with radiation-sparing regimens including intraventricular methotrexate

PURPOSE/METHODS: Clinical and molecular risk factors in 142 patients <5 years with desmoplastic medulloblastoma (DMB) or medulloblastoma with extensive nodularity (MBEN) were investigated. Patients were diagnosed between 1992 and 2020 and treated with radiation-sparing approaches, 131 with intraventricular methotrexate. 14 patients with metastatic disease received high-dose chemotherapy. DNA methylation profiles of 77 sonic hedgehog (SHH)-activated medulloblastoma were reclassified according to the Heidelberg Brain Tumor Classifier Version 12.3. RESULTS: While metastatic disease or incomplete resection did not impact progression-free survival (PFS) and overall survival (OS), patients with MBEN had superior outcomes to DMB (5-year PFS 93% vs 71%, p=0.004; 5-year OS 100% vs 90%, p=0.026). Older patients had less favorable PFS (5-year PFS [>3 years] 47% vs 85% [<1 year] vs 84% [1-3 years], p<0.001). No TP53 mutations were detected (n=47). DNA methylation classification identified three subgroups: SHH-1_v12.3 (n=39), SHH-2_v12.3 (n=19), and SHH-3_v12.3 (n=19), with distinct cytogenetic profiles (chromosome 2 gains in SHH-1_v12.3, very few alterations in SHH-2_v12.3, and chromosome 9q losses in SHH-3_v12.3), age profiles (median age [years] SHH-1_v12.3: 1.7, SHH-2_v12.3: 0.9, SHH-3_v12.3: 3.0, p<0.001), and histological distribution (SHH-2_v12.3: 74% MBEN, SHH-1_v12.3/SHH-3_v12.3: 77%/79% DMB, p<0.001). PFS was more unfavorable in patients with SHH-3_v12.3-medulloblastoma (5-year PFS 53% vs 86% [SHH-1_v12.3] vs 95% [SHH-2_v12.3], p=0.002), which remained the only risk factor on multivariable Cox regression for PFS. OS was comparable (5-year OS 94% [SHH-3_v12.3] vs 97% [SHH-1_v12.3] vs 100% [SHH-2_v12.3], p=0.6). 8/9 patients with SHH-3_v12.3-medulloblastoma received radiotherapy at relapse (6 craniospinal, 2 local [1 Gorlin syndrome, 1 BRCA2 germline mutation], 1 no radiotherapy [Gorlin syndrome]). CONCLUSION: We identify patients with an increased risk of relapse when treated with radiation-sparing approaches among children with early childhood SHH-medulloblastoma. If these tumors differ from SHH-3-medulloblastoma typically described in older children remains to be verified. Treatment recommendations need to consider cancer predisposition syndromes.

Gene expression profiling of Group 3 medulloblastomas defines a clinically tractable stratification based on KIRREL2 expression

Medulloblastomas (MB) molecularly designated as Group 3 (Grp 3) MB represent a more clinically aggressive tumor variant which, as a group, displays heterogeneous molecular characteristics and disease outcomes. Reliable risk stratification of Grp 3 MB would allow for appropriate assignment of patients to aggressive treatment protocols and, vice versa, for sparing adverse effects of high-dose radio-chemotherapy in patients with standard or low-risk tumors. Here we performed RNA-based analysis on an international cohort of 179 molecularly designated Grp 3 MB treated with HIT protocols. We analyzed the clinical significance of differentially expressed genes, thereby developing optimal prognostic subdivision of this MB molecular group. We compared the transcriptome profiles of two Grp 3 MB subsets with various outcomes (76 died within the first 60 months vs. 103 survived this period) and identified 224 differentially expressed genes (DEG) between these two clinical groups (Limma R algorithm, adjusted p-value < 0.05). We selected the top six DEG overexpressed in the unfavorable cohort for further survival analysis and found that expression of all six genes strongly correlated with poor outcomes. However, only high expression of KIRREL2 was identified as an independent molecular prognostic indicator of poor patients' survival. Based on clinical and molecular patterns, four risk categories were outlined for Grp 3 MB patients: i. low-risk: M0-1/MYC non-amplified/KIRREL2 low (n = 48; 5-year OS-95%); ii. standard-risk: M0-1/MYC non-amplified/KIRREL2 high or M2-3/MYC non-amplified/KIRREL2 low (n = 65; 5-year OS-70%); iii. high-risk: M2-3/MYC non-amplified/KIRREL2 high (n = 36; 5-year OS-30%); iv. very high risk-all MYC amplified tumors (n = 30; 5-year OS-0%). Cross-validated survival models incorporating KIRREL2 expression with clinical features allowed for the reclassification of up to 50% of Grp 3 MB patients into a more appropriate risk category. Finally, KIRREL2 immunopositivity was also identified as a predictive indicator of Grp 3 MB poor survival, thus suggesting its application as a possible prognostic marker in routine clinical settings. Our results indicate that integration of KIRREL2 expression in risk stratification models may improve Grp 3 MB outcome prediction. Therefore, simple gene and/or protein expression analyses for this molecular marker could be easily adopted for Grp 3 MB prognostication and may help in assigning patients to optimal therapeutic approaches in prospective clinical trials.

Two faces of temporal binding: Action- and effect-binding are not correlated

Research on the sense of agency has proliferated a range of explicit and implicit measures. However, the relation of different measures is poorly understood with especially mixed findings on the correlation between explicit judgments of agency and the implicit perceptual bias of temporal binding. Here, we add to the conundrum by showing that the two sub-components of temporal binding - action-binding and effect-binding, respectively - are not correlated across participants either, suggesting independent processes for both components. Research on inter-individual differences regarding the sense of agency is thus well-advised to rely on other implicit measures until the phenomenon of temporal binding is better understood.

Quality improvement in neurology: AAN epilepsy quality measures: Report of the Quality Measurement and Reporting Subcommittee of the American Academy of Neurology

OBJECTIVE

Epilepsy is a common neurologic condition with significant personal, societal, medical, and economic burdens. There are considerable gaps in the quality of care delivered. Measuring the quality of care delivered is the first step to its improvement. Performance measures are easily identified and quantitated ways to assess whether specific activities were carried out during a patient encounter. Therefore, epilepsy performance measures were derived through a standardized systematic process and may be the basis for pay-for-performance initiatives and maintenance of certification requirements.

METHODS

Epilepsy measures were developed through the American Medical Association-convened Physician Consortium for Performance Improvement (PCPI) independent measure development process, which marked the first time a medical specialty society followed this process. Guidelines, measures, and consensus papers reviewed for the period 1998 to 2008 using the National Guidelines Clearinghouse, the National Quality Measures Clearinghouse, PubMed, MEDLINE, and the Cochrane Library were evaluated using a framework to determine the acceptability of each guideline or other evidence review document for measures development. Recommendation statements based on level of evidence, importance, validity, and gap in care were developed into candidate measures. A panel of experts from representative organizations vetted the measures. A period of public comment was followed by approval from the American Academy of Neurology and the PCPI.

RESULTS

Literature search identified 160 relevant recommendation statements from 19 guidelines and 2 consensus papers. Systematic assessment resulted in 20 recommendation statements that were refined to 8 candidate measures by the expert panel. The measures are relevant to seizure type and frequency, etiology or epilepsy syndrome, EEG, neuroimaging, antiepileptic drug side effects, safety issues, referral for refractory epilepsy, and issues for women of childbearing potential.

CONCLUSION

There is a reasonable evidence base, and consensus for, deriving performance measures for quality of epilepsy care. It is anticipated that implementation of these performance measures will improve care for patients with epilepsy if adopted by providers.

Quality improvement in neurology: AAN Parkinson disease quality measures: report of the Quality Measurement and Reporting Subcommittee of the American Academy of Neurology

BACKGROUND

Measuring the quality of health care is a fundamental step toward improving health care and is increasingly used in pay-for-performance initiatives and maintenance of certification requirements. Measure development to date has focused on primary care and common conditions such as diabetes; thus, the number of measures that apply to neurologic care is limited. The American Academy of Neurology (AAN) identified the need for neurologists to develop measures of neurologic care and to establish a process to accomplish this.

OBJECTIVE

To adapt and test the feasibility of a process for independent development by the AAN of measures for neurologic conditions for national measurement programs.

METHODS

A process that has been used nationally for measure development was adapted for use by the AAN. Topics for measure development are chosen based upon national priorities, available evidence base from a systematic literature search, gaps in care, and the potential impact for quality improvement. A panel composed of subject matter and measure development methodology experts oversees the development of the measures. Recommendation statements and their corresponding level of evidence are reviewed and considered for development into draft candidate measures. The candidate measures are refined by the expert panel during a 30-day public comment period and by review by the American Medical Association for Current Procedural Terminology (CPT) II codes. All final AAN measures are approved by the AAN Board of Directors.

RESULTS

Parkinson disease (PD) was chosen for measure development. A review of the medical literature identified 258 relevant recommendation statements. A 28-member panel approved 10 quality measures for PD that included full specifications and CPT II codes.

CONCLUSION

The AAN has adapted a measure development process that is suitable for national measurement programs and has demonstrated its capability to independently develop quality measures.

Establishment of primary stroke centers: a survey of physician attitudes and hospital resources

OBJECTIVES

To survey US physicians involved in acute stroke care to determine the proportion of hospitals that currently meet the recommended Brain Attack Coalition (BAC) criteria for Primary Stroke Centers (PSC) and obtain opinions regarding the value of stroke centers.

METHODS

A survey regarding the BAC guidelines for the establishment of stroke centers was mailed to 3,245 US neurologists, neurosurgeons, and emergency physicians.

RESULTS

A total of 1,032 responses were received. Seventy-nine percent (range by specialty 58 to 98%) of respondents believed there was a need for stroke centers. If formal stroke center designation were established, 81% (range 72 to 90%) would like their hospital to become a PSC. Although 77% of respondents believed that their hospital currently met recommended criteria for a PSC, only 7% actually meet all recommended elements. However, 44% of hospitals already provide most acute stroke services. The BAC criteria most frequently lacking were continuing medical education for professional stroke center staff, stroke training for emergency department staff, formal establishment of a stroke unit, and designation of a stroke center director.

CONCLUSIONS

The majority of emergency medicine and neuroscience physician respondents involved in acute stroke care support the designation of primary stroke centers. Although respondents globally overestimated the extent to which their facilities currently meet BAC recommended criteria for PSC, detailed responses suggested that over 40% of hospitals possess substantial existing acute stroke care resources and are poised to function as PSC with modest additional administrative and financial commitment.