Evaluation of the good tumor response of embryonal tumor with abundant neuropil and true rosettes (ETANTR)

Rare embryonal and sarcomatous central nervous system tumours: State-of-the art and future directions

The introduction of molecular methods into the diagnostics of central nervous system (CNS) tumours and the subsequent deciphering of their molecular heterogeneity has resulted in a significant impact on paediatric neurooncology. Particularly in the field of rare embryonal and sarcomatous CNS tumours, novel tumour types have been delineated and introduced in the recent 5th edition of the WHO classification of CNS tumours. The rarity and novelty of these tumour types result in diagnostic and therapeutic challenges. Apart from distinct histopathological and molecular features, these tumour types exhibit characteristic clinical properties and require different therapeutic approaches for optimal patient management. However, based on the limited availability of clinical data, current therapeutic recommendations have to be based on data from small, predominantly retrospective patient cohorts. Within this article, we provide guidance for diagnostic work-up and clinical management of rare CNS embryonal tumours ('embryonal tumour with multi-layered rosettes', ETMR; 'CNS neuroblastoma, FOXR2-activated', CNS NB-FOXR2; 'CNS tumour with BCOR-ITD, CNS BCOR-ITD) and rare CNS sarcomatous tumours ('primary intracranial sarcoma, DICER1-mutant', CNS DICER1; 'CIC-rearranged sarcoma', CNS CIC). By emphasizing the significant consequences on patient management in paediatric CNS tumours, we want to encourage wide implementation of comprehensive molecular diagnostics and stress the importance for joint international efforts to further collect and study these rare tumour types.

Therapeutic implications of improved molecular diagnostics for rare CNS embryonal tumor entities: results of an international, retrospective study

BACKGROUND

Only few data are available on treatment-associated behavior of distinct rare CNS embryonal tumor entities previously treated as "CNS-primitive neuroectodermal tumors" (CNS-PNET). Respective data on specific entities, including CNS neuroblastoma, FOXR2 activated (CNS NB-FOXR2), and embryonal tumors with multilayered rosettes (ETMR) are needed for development of differentiated treatment strategies.

METHODS

Within this retrospective, international study, tumor samples of clinically well-annotated patients with the original diagnosis of CNS-PNET were analyzed using DNA methylation arrays (n = 307). Additional cases (n = 66) with DNA methylation pattern of CNS NB-FOXR2 were included irrespective of initial histological diagnosis. Pooled clinical data (n = 292) were descriptively analyzed.

RESULTS

DNA methylation profiling of "CNS-PNET" classified 58 (19%) cases as ETMR, 57 (19%) as high-grade glioma (HGG), 36 (12%) as CNS NB-FOXR2, and 89(29%) cases were classified into 18 other entities. Sixty-seven (22%) cases did not show DNA methylation patterns similar to established CNS tumor reference classes. Best treatment results were achieved for CNS NB-FOXR2 patients (5-year PFS: 63% ± 7%, OS: 85% ± 5%, n = 63), with 35/42 progression-free survivors after upfront craniospinal irradiation (CSI) and chemotherapy. The worst outcome was seen for ETMR and HGG patients with 5-year PFS of 18% ± 6% and 22% ± 7%, and 5-year OS of 24% ± 6% and 25% ± 7%, respectively.

CONCLUSION

The historically reported poor outcome of CNS-PNET patients becomes highly variable when tumors are molecularly classified based on DNA methylation profiling. Patients with CNS NB-FOXR2 responded well to current treatments and a standard-risk CSI-based regimen may be prospectively evaluated. The poor outcome of ETMR across applied treatment strategies substantiates the necessity for evaluation of novel treatments.

Embryonal tumors with multilayered rosettes: A tertiary care centre experience

BACKGROUND

Embryonal tumors with multilayered rosettes (ETMR) is an extremely rare and highly aggressive tumor. It includes three distinct entities i.e, embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma (EBL) and medulloepithelioma (MEPL). Here, we present our institutional experience of seven ETMR cases treated over a period of five years.

MATERIALS AND METHODS

Patients' records from 2015 to 2019 were reviewed manually and electronically to retrieve the data. Clinicopathological and outcome details of ETMR cases were entered in a predesigned proforma.

RESULTS

A total of seven cases of ETMR were registered from 2015 to 2019 with a median age at presentation of four years (range 3-7 years). All patients underwent surgery. However, only three patients completed the planned adjuvant treatment, comprising of focal radiotherapy (RT) alone, craniospinal irradiation (CSI) alone and CSI followed by six cycles of chemotherapy in one patient each respectively. Two patients commenced CSI but deteriorated during RT and thereafter needed best supportive care. Two patients could not be started on any adjuvant treatment. Unfortunately, six patients succumbed to their disease within one year of their diagnosis. Only one patient who received both CSI and adjuvant chemotherapy is alive at 15 months of diagnosis.

CONCLUSION

ETMR is a rare and aggressive entity. Majority of the patients die within one year of the diagnosis despite multimodality treatment.

Potential Importance of Early Focal Radiotherapy Following Gross Total Resection for Long-Term Survival in Children With Embryonal Tumors With Multilayered Rosettes

Embryonal tumor with multilayered rosettes (ETMR) is a rare, aggressive embryonal central nervous system tumor characterized by LIN28A expression and alterations in the C19MC locus. ETMRs predominantly occur in young children, have a dismal prognosis, and no definitive treatment guidelines have been established. We report on nine consecutive patients and review the role of initiation/timing of radiotherapy on survival. Between 2006 and 2018, nine patients were diagnosed with ETMR. Diagnosis was confirmed histopathologically, immunohistochemically and molecularly. Median age was 25 months (5–38). Location was supratentorial in five, pineal in three, and brainstem in one. Seven patients had a gross total resection, one a partial resection and one a biopsy at initial diagnosis. Chemotherapy augmented with intrathecal therapy started a median of 10 days (7–20) after surgery. Only two patients who after gross total resection received radiotherapy very early on (six weeks after diagnosis) are alive and in complete remission 56 and 50 months after diagnosis. All remaining patients for whom radiotherapy was deferred until the end of chemotherapy recurred, albeit none with leptomeningeal disease. A literature research identified 228 patients with ETMR. Including our patients only 26 (11%) of 237 patients survived >36 months with no evidence of disease at last follow-up. All but two long-term (>36 months) survivors received radiotherapy, ten of whom early on following gross total resection (GTR). GTR followed by early focal radiotherapy and intrathecal therapy to prevent leptomeningeal disease are potentially important to improve survival of ETMR in the absence of effective targeted therapies.

Targeted radioimmunotherapy for embryonal tumor with multilayered rosettes

PURPOSE

We explored the use of intraventricular ¹³¹I-Omburtamab targeting B7-H3 in patients with ETMR.

METHODS

Patients were enrolled in an IRB approved, phase 1, 3 + 3 dose escalation trial. Patients with CNS disease expressing the antibody target antigen B7-H3 were eligible. We report on a cohort of three patients with ETMR who were enrolled on the study. Three symptomatic children (ages 14 months, 3 and 3.5 years) had large parietal masses confirmed to be B7-H3-reactive ETMR. Patients received 2 mCi ¹³¹I-Omburtamab as a tracer followed by one or two therapeutic ¹³¹I-Omburtamab injections. Dosimetry was based on serial CSF, blood samplings and region of interest (ROI) on nuclear scans. Brain and spine MRIs and CSF cytology were done at baseline, 5 weeks after ¹³¹I-Omburtamab, and approximately every 3 months thereafter. Acute toxicities and survival were noted.

RESULTS

Patients received surgery, focal radiation, and high dose chemotherapy. Patients 1 and 2 received ¹³¹I-Omburtamab (80 and 53 mCi, respectively). Patient 3 had a local recurrence prior to ¹³¹I-Omburtamab treated with surgery, external beam radiation, chemotherapy, then ¹³¹I-Omburtamab (36 mCi). ¹³¹I-Omburtamab was well-tolerated. Mean dose delivered by ¹³¹I-Omburtamab was 68.4 cGy/mCi to CSF and 1.95 cGy/mCi to blood. Mean ROI doses were 230.4 (ventricular) and 58.2 (spinal) cGy/mCi. Patients 1 and 2 remain in remission 6.8 years and 2.3 years after diagnosis, respectively; patient 3 died of progressive disease 7 months after therapy (2 years after diagnosis).

CONCLUSIONS

¹³¹I-Omburtamab appears safe with favorable dosimetry therapeutic index. When used as consolidation following surgery and chemoradiation therapy, ¹³¹I-Omburtamab may have therapeutic benefit for patients with ETMR.

Embryonal tumor with multilayered rosettes: illustrative case and review of the literature

BACKGROUND

Embryonal tumor with multilayered rosettes (ETMR) is a very rare entity and has seldom been reported. It has been newly defined tumor entity included in the latest update (revised fourth edition) of WHO 2016 Classification of Tumors of the Central Nervous System which portends a uniform dismal prognosis and survival even with the best of multimodality approaches.

ILLUSTRATIVE CASE

This report documents the presentation of a 2-year-old girl with voluminous intracranial ETMR in the right parieto-occipital region. We describe clinical diagnosis, histological aspects, radiological features, and current management of this very aggressive tumor.

CONCLUSION

Pediatric intracranial ETMR is a highly aggressive neoplasm, and it should be considered in the differential diagnosis of pediatric brain tumors.

Radiation for ETMR: Literature review and case series of patients treated with proton therapy

Background and purpose

Embryonal tumors with multilayered rosettes (ETMRs) are aggressive tumors that typically occur in young children. Radiation is often deferred or delayed for these patients due to late effects; proton therapy may mitigate some of these concerns. This study reviews the role of radiation in ETMR and describes initial results with proton therapy.

Materials and methods

Records of patients with embryonal tumor with abundant neuropil and true rosettes (ETANTR), medulloepithelioma (MEP), and ependymoblastoma (EPL) treated with proton therapy at our institution were retrospectively reviewed. A literature review of cases of CNS ETANTR, MEP, and EPL published since 1990 was also conducted.

Results

Seven patients were treated with proton therapy. Their median age at diagnosis was 33 months (range 10-57 months) and their median age at radiation start was 42 months (range 17-58 months). Their median overall survival (OS) was 16 months (range 8-64 months), with three patients surviving 36 months or longer. Five patients had disease progression prior to starting radiation; all 5 of these patients failed in the tumor bed. A search of the literature identified 204 cases of ETMR with a median OS of 10 months (range 0.03-161 months). Median OS of 18 long-term survivors (≥36 months) in the literature was 77 months (range 37-184 months). Of these 18 long-term survivors, 17 (94%) received radiotherapy as part of their initial treatment; 14 of them were treated with craniospinal irradiation.

Conclusions

Outcomes of patients with ETMR treated with proton therapy are encouraging compared to historical results. Further study of this rare tumor is warranted to better define the role of radiotherapy.

Preclinical drug screen reveals topotecan, actinomycin D, and volasertib as potential new therapeutic candidates for ETMR brain tumor patients

Background

Embryonal tumor with multilayered rosettes (ETMR) is a rare and aggressive embryonal brain tumor that solely occurs in infants and young children and has only recently been recognized as a separate brain tumor entity in the World Health Organization classification for CNS tumors. Patients have a very dismal prognosis with a median survival of 12 months upon diagnosis despite aggressive treatment. The aim of this study was to develop novel treatment regimens in a preclinical drug screen in order to inform potentially more active clinical trial protocols.

Methods

We have carried out an in vitro and in vivo drug screen using the ETMR cell line BT183 and its xenograft model. Furthermore, we have generated the first patient-derived xenograft (PDX) model for ETMR and evaluated our top drug candidates in an in vitro drug screen using this model.

Results

BT183 cells are very sensitive to the topoisomerase inhibitors topotecan and doxorubicin, to the epigenetic agents decitabine and panobinostat, to actinomycin D, and to targeted drugs such as the polo-like kinase 1 (PLK1) inhibitor volasertib, the aurora kinase A inhibitor alisertib, and the mammalian target of rapamycin (mTOR) inhibitor MLN0128. In xenograft mice, monotherapy with topotecan, volasertib, and actinomycin D led to a temporary response in tumor growth and a significant increase in survival. Finally, using multi-agent treatment regimens of topotecan or doxorubicin combined with methotrexate and vincristine, the response in tumor growth and survival was further increased compared with mice receiving single treatments.

Conclusions

We have identified several promising candidates for combination therapies in future clinical trials for ETMR patients.