Development of Randomized Trials in Adults with Medulloblastoma-The Example of EORTC 1634-BTG/NOA-23

Central nervous system tumors in adolescents and young adults: A Society for Neuro-Oncology consensus review on diagnosis, management, and future directions

Adolescents and young adults (AYAs; ages 15-39 years) are a vulnerable population facing challenges in oncological care, including access to specialized care, transition of care, unique tumor biology, and poor representation in clinical trials. Brain tumors are the second most common tumor type in AYA, with malignant brain tumors being the most common cause of cancer-related death. The 2021 WHO Classification for central nervous system (CNS) Tumors highlights the importance of integrated molecular characterization with histologic diagnosis in several tumors relevant to the AYA population. In this position paper from the Society for Neuro-Oncology (SNO), the diagnosis and management of CNS tumors in AYA is reviewed, focusing on the most common tumor types in this population, namely glioma, medulloblastoma, ependymoma, and CNS germ cell tumor. Current challenges and future directions specific to AYA are also highlighted. Finally, possible solutions to address barriers in the care of AYA patients are discussed, emphasizing the need for multidisciplinary and collaborative approaches that span the pediatric and adult paradigms of care, and incorporating advanced molecular testing, targeted therapy, and AYA-centered care.

Medulloblastoma in adults: an analysis of clinico-pathological, molecular and treatment factors

BACKGROUND

Medulloblastoma is a highly malignant, embryonal tumor, which is rare in adults, and shows distinct clinical, histopathological, molecular and treatment response features.

METHODS

We retrospectively investigated 44 adults (age 17-48 years) with a histological diagnosis of medulloblastoma, and in 23 immunohistochemistry was used to identify the molecular subgroups. We analyzed demographic, diagnostic, therapeutic and cognitive data, and correlated with PFS (progression-free-survival) and OS (overall survival).

RESULTS

We observed a male prevalence and a median age of 31 years. Symptoms at onset were related to infratentorial location, while myeloradicular and/or cranial nerve involvement was rare. Histological examination showed the classic variant in 75% of patients, the desmoplastic/nodular in 23% and the anaplastic in one. As for molecular diagnosis, 17 patients were SHH and 6 non-WNT/non-SHH (5 group 4 and 1 group 3), while no WNT subgroup was found. The SHH subgroup had a prevalence of high-risk patients and leptomeningeal involvement. Patients underwent gross total or subtotal/partial resection, and craniospinal irradiation, followed in 20 cases by adjuvant chemotherapy. Median OS and PFS were 16.9 and 12 years, respectively. Metastatic disease at presentation and subtotal/partial resection were associated with worse prognosis, while the addition of chemotherapy did not yield a significant advantage over radiotherapy alone. Cognitive impairment in long-term survivors was limited and late relapses occurred in 15% of patients.

CONCLUSIONS

Future studies with adequate sample size and long-term follow-up should prospectively investigate the role of surgery and adjuvant therapies across the different molecular subgroups to see whether a personalized approach is feasible.

Primary brain tumours in adults

The most frequent adult-type primary CNS tumours are diffuse gliomas, but a large variety of rarer CNS tumour types exists. The classification of these tumours is increasingly based on molecular diagnostics, which is reflected in the extensive molecular foundation of the recent WHO 2021 classification of CNS tumours. Resection as extensive as is safely possible is the cornerstone of treatment in most gliomas, and is now also recommended early in the treatment of patients with radiological evidence of histologically low-grade tumours. For the adult-type diffuse glioma, standard of care is a combination of radiotherapy and chemotherapy. Although treatment with curative intent is not available, combined modality treatment has resulted in long-term survival (>10-20 years) for some patients with isocitrate dehydrogenase (IDH) mutant tumours. Other rarer tumours require tailored approaches, best delivered in specialised centres. Targeted treatments based on molecular alterations still only play a minor role in the treatment landscape of adult-type diffuse glioma, and today are mainly limited to patients with tumours with BRAFV600E (ie, Val600Glu) mutations. Immunotherapy for CNS tumours is still in its infancy, and so far, trials with checkpoint inhibitors and vaccination studies have not shown improvement in patient outcomes in glioblastoma. Current research is focused on improving our understanding of the immunosuppressive tumour environment, the molecular heterogeneity of tumours, and the role of tumour microtube network connections between cells in the tumour microenvironment. These factors all appear to play a role in treatment resistance, and indicate that novel approaches are needed to further improve outcomes of patients with CNS tumours.

Central nervous system germ cell tumor, an archetypal AYA tumor and a model for pediatric and neuro-oncology collaboration, review from the EURACAN domain 10 group

Simple Summary: Adolescents and young adults (AYA) with cancer often fall through gaps between children's and adults' cancer services. They are consequently under-represented in clinical trials, and their survival is often inferior to that of children or adults with the same tumor type; in this paper, we use the example of central nervous system germ cell tumors (CNS-GCT), as a model of AYA tumor to illustrate this challenge. We describe how we have built bridges between pediatric and adult oncology, how this can apply to other types of brain tumors, and discuss ways to promote cancer care in the AYA population. Adolescents and young adults (AYA) with cancer are under-represented in clinical trials and have thus not benefited from the same improvement in outcomes as either younger or older patients. Central nervous system germ cell tumors (CNS-GCT) represent an ideal model of AYA tumor as their incidence peaks during adolescence and young adulthood. Since the early 90's, SIOP (International Society of Pediatric Oncology) has launched two successive European trials: SIOP CNS-GCT96 (January 1996 to December 2005) and SIOP CNS-GCTII protocols (October 2011 to July 2018), for CNS-GCTs. With the removal of the upper age limit in the SIOP CNS-GCTII trial, and closer collaboration between pediatric and adult oncologists within AYA multidisciplinary tumor boards, the proportion of adults enrolled in France has dramatically increased over time. The current article will use the example of CNS-GCT to illustrate how to build a bridge between pediatric and adult oncology, how this can apply to other types of brain tumors, and how to promote cancer care in the AYA population.

Adult Medulloblastoma: Updates on Current Management and Future Perspectives

Medulloblastoma (MB) is a malignant embryonal tumor of the posterior fossa belonging to the family of primitive neuro-ectodermic tumors (PNET). MB generally occurs in pediatric age, but in 14–30% of cases, it affects the adults, mostly below the age of 40, with an incidence of 0.6 per million per year, representing about 0.4–1% of tumors of the nervous system in adults. Unlike pediatric MB, robust prospective trials are scarce for the post-puberal population, due to the low incidence of MB in adolescent and young adults. Thus, current MB treatments for older patients are largely extrapolated from the pediatric experience, but the transferability and applicability of these paradigms to adults remain an open question. Adult MB is distinct from MB in children from a molecular and clinical perspective. Here, we review the management of adult MB, reporting the recent published literature focusing on the effectiveness of upfront chemotherapy, the development of targeted therapies, and the potential role of a reduced dose of radiotherapy in treating this disease.

Adult medulloblastoma in an Australian population

Medulloblastoma in adult patients is a rare condition with limited contemporary demographic and treatment outcome data available in an Australian population. We conducted a retrospective review of patterns of care and outcomes of adult patients diagnosed with medulloblastoma treated at major neuro-oncology centres across Australia between January 2010 and December 2019. A total of 80 patients were identified and the median follow-up after diagnosis was 59.2 (range 0.5-204) months. A variety of chemotherapy regimens were used in the adjuvant and recurrent settings. The median overall survival (mOS) was 78 months (IQR 17.5-94.8). Patients who had no residual disease post-resection or with SHH-subtype tumours had a numerically longer 5-year survival rate than those with residual disease post resection or non-SHH subtypes respectively. The median time to recurrence from diagnosis was 18.4 months. The median OS from 1st relapse was 22.1 months (95% CI 11.7-31.4) and mOS from second relapse was 10.2 months (95% CI 6.6 - NR). This is the largest dataset examining patterns of care of adult patients with medulloblastoma in an Australian population. Substantial variation existed in the chemotherapy agents used in the adjuvant and recurrent setting. As has been demonstrated in a paediatric population, trials such as the upcoming EORTC 1634-BTG/NOA-23 trial (PersoMed-1 study) which are tailoring treatments to molecular profiles are likely to improve outcome in adult medulloblastoma.

Predictive modeling of resistance to SMO-inhibition in a patient-derived orthotopic xenograft model of SHH medulloblastoma

Background

Inhibition of the sonic hedgehog (SHH) pathway with Smoothened (SMO) inhibitors is a promising treatment strategy in SHH-activated medulloblastoma, especially in adult patients. However, the problem is that tumors frequently acquire resistance to the treatment. To understand the underlying resistance mechanisms and to find ways to overcome the resistance, preclinical models that became resistant to SMO inhibition are needed.

Methods

To induce SMO inhibitor resistant tumors, we have treated a patient-derived xenograft (PDX) model of SHH medulloblastoma, sensitive to SMO inhibition, with 20 mg/kg Sonidegib using an intermitted treatment schedule. Vehicle-treated and resistant models were subjected to whole-genome and RNA sequencing for molecular characterization and target engagement. In vitro drug screens (76 drugs) were performed using Sonidegib-sensitive and -resistant lines to find other drugs to target the resistant lines. One of the top hits was then validated in vivo.

Results

Nine independent Sonidegib-resistant PDX lines were generated. Molecular characterization of the resistant models showed that eight models developed missense mutations in SMO and one gained an inactivating point mutation in MEGF8, which acts downstream of SMO as a repressor in the SHH pathway. The in vitro drug screen with Sonidegib-sensitive and -resistant lines identified good efficacy for Selinexor in the resistant line. Indeed, in vivo treatment with Selinexor revealed that it is more effective in resistant than in sensitive models.

Conclusions

We report the first human SMO inhibitor resistant medulloblastoma PDX models, which can be used for further preclinical experiments to develop the best strategies to overcome the resistance to SMO inhibitors in patients.

Molecular Targeted Therapies: Time for a Paradigm Shift in Medulloblastoma Treatment?

Medulloblastoma is a rare malignancy of the posterior cranial fossa. Although until now considered a single disease, according to the current WHO classification, it is a heterogeneous tumor that comprises multiple molecularly defined subgroups, with distinct gene expression profiles, pathogenetic driver alterations, clinical behaviors and age at onset. Adult medulloblastoma, in particular, is considered a rarer "orphan" entity in neuro-oncology practice because while treatments have progressively evolved for the pediatric population, no practice-changing prospective, randomized clinical trials have been performed in adults. In this scenario, the toughest challenge is to transfer the advances in cancer genomics into new molecularly targeted therapeutics, to improve the prognosis of this neoplasm and the treatment-related toxicities. Herein, we focus on the recent advances in targeted therapy of medulloblastoma based on the new and deeper knowledge of disease biology.

Radiotherapy in Medulloblastoma-Evolution of Treatment, Current Concepts and Future Perspectives

Simple Summary

Craniospinal irradiation (CSI) is the backbone of medulloblastoma treatment and the first treatment to achieve a cure in many patients. Within the last decades, significant efforts have been made to enhance efficacy in combination with chemotherapy. With this approach, a majority of low- and standard-risk patients can be cured. In parallel, many clinical trials have dealt with CSI-dose reduction and reduction of boost volume in order to decrease long-term toxicity, particularly neurotoxicity. Within these trials, standardized quality assurance has helped to increase the accuracy of treatment and improve prognosis. More recently, advances of radiotherapy techniques such as proton treatment allowed for better sparing of healthy tissue in order to further diminish detrimental long-term effects. Major future challenges are the adaption of radiotherapy regimens to different molecularly defined disease groups alone or together with new targeted agents. Moreover, and even more importantly, innovative combinatorial treatments are needed in high- and very-high risk situations.

Abstract

Medulloblastoma is the most frequent malignant brain tumor in children. During the last decades, the therapeutic landscape has changed significantly with craniospinal irradiation as the backbone of treatment. Survival times have increased and treatments were stratified according to clinical and later molecular risk factors. In this review, current evidence regarding the efficacy and toxicity of radiotherapy in medulloblastoma is summarized and discussed mainly based on data of controlled trials. Current concepts and future perspectives based on current risk classification are outlined. With the introduction of CSI, medulloblastoma has become a curable disease. Due to combination with chemotherapy, survival rates have increased significantly, allowing for a reduction in radiation dose and a decrease of toxicity in low- and standard-risk patients. Furthermore, modern radiotherapy techniques are able to avoid side effects in a fragile patient population. However, high-risk patients remain with relevant mortality and many patients still suffer from treatment related toxicity. Treatment needs to be continually refined with regard to more efficacious combinatorial treatment in the future.