Efficacy of temozolomide for recurrent embryonal brain tumors in children

ESTRO-SIOPE guideline: Clinical management of radiotherapy in atypical teratoid/rhabdoid tumors (AT/RTs)

BACKGROUND AND PURPOSE

Treatment of patients with atypical teratoid/rhabdoid (AT/RT) is challenging, especially when very young (below the age of three years). Radiotherapy (RT) is part of a complex trimodality therapy. The purpose of this guideline is to provide appropriate recommendations for RT in the clinical management of patients not enrolled in clinical trials.

MATERIALS AND METHODS

Nine European experts were nominated to form a European Society for Radiotherapy and Oncology (ESTRO) guideline committee. A systematic literature search was conducted in PubMed/MEDLINE and Web of Science. They discussed and analyzed the evidence concerning the role of RT in the clinical management of AT/RT.

RESULTS

Recommendations on diagnostic imaging, therapeutic principles, RT considerations regarding timing, dose, techniques, target volume definitions, dose constraints of radiation-sensitive organs at risk, concomitant chemotherapy, and follow-up were considered. Treating children with AT/RT within the framework of prospective trials or prospective registries is of utmost importance.

CONCLUSION

The present guideline summarizes the evidence and clinical-based recommendations for RT in patients with AT/RT. Prospective clinical trials and international, large registries evaluating modern treatment approaches will contribute to a better understanding of the best treatment for these children in future.

An Adult Case of Sellar Atypical Teratoid/Rhabdoid Tumor Presenting with Lung Metastasis, Harboring a Compound Heterozygous Mutation in INI1

A typical teratoid/rhabdoid tumors (AT/RT) are highly malignant embryonal tumors in children that are associated with inactivation of the integrase interactor 1 (INI1) gene. Several adult cases of AT/RT have been reported, which were characterized by the sellar occurrence and predominantly occurred in females with INI1 mutation variants. However, clinical and genetic features are poorly understood in this unusual entity. We experienced a case of a 45-year-old female with sellar AT/RT presenting diplopia, who underwent subtotal removal of the tumor by the endoscopic endonasal transsphenoidal approach. Pathological diagnosis was AT/RT with INI1 inactivation on immunohistochemistry. Subsequently, multiple lung metastases were confirmed on fluorodeoxyglucose positron emission tomography (FDG-PET). Although she received postoperative chemoradiotherapy, she died of cerebrospinal fluid dissemination. Autopsy revealed cerebrospinal dissemination and lung metastasis of AT/RT. Biallelic alterations in the INI1 gene were identified by direct sequencing, harboring on different alleles (compound heterozygous mutations) was observed, which is the potential genetic pattern in adult AT/RT. Literature review indicated that lung metastasis frequently occurs in sellar AT/RTs, which is accompanied by cavernous sinus invasion. These observations suggested that cavernous sinus invasion causes haematogenous metastasis to the lung in sellar AT/RT. We discuss clinical and pathological features in adult sellar AT/RT to improve understanding of this unique entity.

Relapsed Medulloblastoma in Pre-Irradiated Patients: Current Practice for Diagnostics and Treatment

Relapsed medulloblastoma (rMB) accounts for a considerable, and disproportionate amount of childhood cancer deaths. Recent advances have gone someway to characterising disease biology at relapse including second malignancies that often cannot be distinguished from relapse on imaging alone. Furthermore, there are now multiple international early-phase trials exploring drug-target matches across a range of high-risk/relapsed paediatric tumours. Despite these advances, treatment at relapse in pre-irradiated patients is typically non-curative and focuses on providing life-prolonging and symptom-modifying care that is tailored to the needs and wishes of the individual and their family. Here, we describe the current understanding of prognostic factors at disease relapse such as principal molecular group, adverse molecular biology, and timing of relapse. We provide an overview of the clinical diagnostic process including signs and symptoms, staging investigations, and molecular pathology, followed by a summary of treatment modalities and considerations. Finally, we summarise future directions to progress understanding of treatment resistance and the biological mechanisms underpinning early therapy-refractory and relapsed disease. These initiatives include development of comprehensive and collaborative molecular profiling approaches at relapse, liquid biopsies such as cerebrospinal fluid (CSF) as a biomarker of minimal residual disease (MRD), modelling strategies, and the use of primary tumour material for real-time drug screening approaches.

Advancing biology-based therapeutic approaches for atypical teratoid rhabdoid tumors

Atypical teratoid rhabdoid tumor (ATRT) is a rare, highly malignant central nervous system cancer arising in infants and younger children, historically considered to be homogeneous, monogenic, and incurable. Recent use of intensified therapies has modestly improved survival for ATRT; however, a majority of patients will still succumb to their disease. While ATRTs almost universally exhibit loss of SMARCB1 (BAF47/INI1/SNF5), recent whole genome, transcriptome, and epigenomic analyses of large cohorts reveal previously underappreciated molecular heterogeneity. These discoveries provide novel insights into how SMARCB1 loss drives oncogenesis and confer specific therapeutic vulnerabilities, raising exciting prospects for molecularly stratified treatment for patients with ATRT.

Temozolomide and oral etoposide in children with recurrent malignant brain tumors

Despite advances in the treatment of brain tumors, the prognosis of children with recurrent malignant brain tumors remains poor. Etoposide (VP-16), an inhibitor of nuclear enzyme deoxyribonucleic acid (DNA)-topoisomerase II, has shown activity in brain tumors. Its efficacy appears schedule dependent but, to date, the most effective schedule of administration has not been well defined. Temozolomide (TMZ), like VP-16, penetrates the blood-brain barrier and has activity against malignant brain tumors. This novel alkylating agent is rapidly absorbed and is highly bioavailable after oral administration. The antitumor activity of TMZ has been shown to be schedule dependent. Based on the evidence of different mechanisms of cytotoxicity, TMZ and VP-16 have been utilized in combination in patients with malignant brain tumors. This review evaluates the results derived from the combination use of TMZ and oral VP-16. The reported data suggest potential activity of oral VP-16 and TMZ alone or in combination. Further clinical trials are needed to explore and confirm their promising activity in relapsed brain neoplasms.

Phase II study of temozolomide and topotecan (TOTEM) in children with relapsed or refractory extracranial and central nervous system tumors including medulloblastoma with post hoc Bayesian analysis: A European ITCC study

AIM

To assess objective response after two cycles of temozolomide and topotecan (TOTEM) in children with refractory or relapsed miscellaneous extracranial solid and central nervous system (CNS) tumors, including medulloblastoma and primitive neuroectodermal tumors (PNET).

PROCEDURE

Multicenter, nonrandomized, phase 2 basket trial including children with solid tumors, completed by a one-stage design confirmatory cohort for medulloblastoma, and an exploratory cohort for PNET. Main eligibility criteria were refractory/relapsed measurable disease and no more than two prior treatment lines. Temozolomide was administered orally at 150 mg/m² /day followed by topotecan at 0.75 mg/m² /day intravenously for five consecutive days every 28 days. Tumor response was assessed every two cycles according to WHO criteria and reviewed independently.

RESULTS

Thirty-two patients were enrolled and treated in the miscellaneous solid tumor and 33 in the CNS strata; 20 patients with medulloblastoma and six with PNET were included in the expansion cohorts. The median age at inclusion was 10.0 years (range, 0.9-20.9). In the basket cohorts, confirmed complete and partial responses were observed in one glioma, four medulloblastoma, and one PNET, leading to the extension. The overall objective response rate (ORR) in medulloblastoma was 28% (95% CI, 12.7-47.2) with 1/29 complete and 7/29 partial responses, those for PNET 10% (95% CI, 0.3-44.5). Post hoc Bayesian analysis estimates that the true ORR in medulloblastoma is probably between 20% and 30% and below 20% in PNET. The most common treatment-related toxicities of the combination therapy were hematologic.

CONCLUSIONS

Temozolomide-topotecan results in significant ORR in children with recurrent and refractory medulloblastoma with a favorable toxicity profile.

Atypical teratoid/rhabdoid tumors: challenges and search for solutions

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant embryonal central nervous system tumor commonly affecting children <3 years of age. It roughly constitutes 1%-2% of all pediatric central nervous system tumors. Recent data show that it is the most common malignant central nervous system tumor in children <6 months of age. Management of this aggressive tumor is associated with a myriad of diagnostic and therapeutic challenges. On the basis of radiology and histopathology alone, distinction of AT/RT from medulloblastoma or primitive neuroectodermal tumor is difficult, and hence this tumor has been commonly misdiagnosed as primitive neuroectodermal tumor for decades. Presence of a bulky heterogeneous solid-cystic mass with readily visible calcification and intratumor hemorrhage, occurring off-midline in children <3 years of age, should alert the radiologist toward the possibility of AT/RT. Presence of rhabdoid cells on histopathology and polyphenotypic immunopositivity for epithelial, mesenchymal, and neuroectodermal markers along with loss of expression of SMARCB1/INI1 or SMARCA4/BRG1 help in establishing a diagnosis of AT/RT. The optimal management comprises maximal safe resection followed by radiation therapy and multiagent intensive systemic chemotherapy. Gross total excision is difficult to achieve in view of the large tumor size and location and young age at presentation. Leptomeningeal spread is noted in 15%-30% of patients, and hence craniospinal irradiation followed by boost to tumor bed is considered standard in children older than 3 years. However, in younger children, craniospinal irradiation may lead to long-term neurocognitive and neuroendocrine sequel, and hence focal radiation therapy may be a pragmatic approach. In this age group, high-dose chemotherapy with autologous stem cell rescue may also be considered to defer radiation therapy, but this approach is also associated with significant treatment-related morbidity and mortality. Novel small molecule inhibitors hold promise in preclinical studies and should be considered in patients with relapsed or refractory tumor.

Peripheral medulloepithelioma: a rare tumor with a potential target therapy

Background

Medulloepithelioma (ME) is a rare embryonal tumor predominantly located in the eye or in the central nervous system without an established treatment.

Case presentation

We report of a case of a localized peripheral ME treated with conventional and high dose chemotherapy, surgery and local radiotherapy. At relapse, the tumor tissue revealed a different molecular signature compared to the initial tumor mass. This molecular signature revealed a high expression of platelet derived growth factor receptor (PDGFR). Sorafenib plus irinotecan and temozolomide was started with a 5 month progression free survival.

Conclusion

Our experience suggests a possible role of sorafenib or different PDGFR inhibitors in ME. Targeting treatment could represent an adjuvant and/or alternative therapy for ME and other rare tumors.

Phase II study of irinotecan in combination with temozolomide (TEMIRI) in children with recurrent or refractory medulloblastoma: a joint ITCC and SIOPE brain tumor study

BACKGROUND

This multicenter phase II study investigated temozolomide + irinotecan (TEMIRI) treatment in children with relapsed or refractory medulloblastoma.

METHODS

Patients received temozolomide 100-125 mg/m(2)/day (days 1-5) and irinotecan 10 mg/m(2)/day (days 1-5 and 8-12) every 3 weeks. The primary endpoint was tumor response within the first 4 cycles confirmed ≥4 weeks and assessed by an external response review committee (ERRC). In a 2-stage Optimum Simon design, ≥6 responses in the first 15 evaluable patients were required within the first 4 cycles for continued enrollment; a total of 19 responses from the first 46 evaluable patients was considered successful.

RESULTS

Sixty-six patients were treated. Seven responses were recorded during stage 1 and 15 in the first 46 ERRC evaluated patients (2 complete responses and 13 partial responses). The objective response rate during the first 4 cycles was 32.6% (95% confidence interval [CI], 19.5%-48.0%). Median duration of response was 27.0 weeks (7.7-44.1 wk). In 63 patients evaluated by local investigators, the objective response rate was 33.3% (95% CI, 22.0%-46.3%), and 68.3% (95% CI, 55.3%-79.4%) experienced clinical benefit. Median survival was 16.7 months (95% CI, 13.3-19.8). The most common grade 3 treatment-related nonhematologic adverse event was diarrhea (7.6%). Grade 3/4 treatment-related hematologic adverse events included neutropenia (16.7%), thrombocytopenia (12.1%), anemia (9.1%), and lymphopenia (9%).

CONCLUSIONS

The planned study primary endpoint was not met. However, its tolerability makes TEMIRI a suitable candidate chemotherapy backbone for molecularly targeted agents in future trials in this setting.

Response to bevacizumab, irinotecan, and temozolomide in children with relapsed medulloblastoma: a multi-institutional experience

PURPOSE

Chemotherapy for relapsed medulloblastoma has been inadequate, and most patients succumb to disease.

METHODS

We retrospectively reviewed nine cases of relapsed medulloblastoma treated with bevacizumab, irinotecan, ± temozolomide. Patients received one to three prior therapeutic regimens. Five patients received 10 mg/kg bevacizumab and 125-150 mg/m(2) irinotecan IV every 2 weeks, with temozolomide, starting at a median dose of 150 mg/m(2) orally for 5 days monthly. Two patients received bevacizumab and irinotecan, but not temozolomide, due to provider preference. Two of nine patients received 15 mg/kg bevacizumab IV, 90 mg/m(2) irinotecan orally for five consecutive days, 100 mg/m(2)/day temozolomide IV for 5 days, and 1.5 mg/m(2) vincristine IV, each administered every 21 days.

RESULTS

Median time to progression was 11 months. Median overall survival was 13 months. Objective tumor response at 3 months was 67 %, including six patients with partial response (PR) and three patients with stable disease (SD). At 6 months, objective response was 55 %, with two patients with PR and three with complete response. Additionally, one patient had SD and three had PD. Two patients remain alive and progression free at 15 and 55 months; another is alive with disease at 20 months. Toxicities included two patients with grade III neutropenia, two with grade III thrombocytopenia, one with grade III elevation of liver function tests, and one patient with grade III diarrhea.

CONCLUSIONS

The combination of bevacizumab and irinotecan, with or without temozolomide, produces objective responses with minimal toxicity in children with recurrent medulloblastoma. Prospective clinical trials are needed to evaluate the efficacy of this strategy.

Temozolomide in relapsed pediatric brain tumors: 14 cases from a single center

AIM

Temozolomide is an active drug against gliomas in adults. It also has some promising effects in pediatric patients with brain tumors. We have conducted a retrospective study to investigate the effectiveness of temozolomide in patients with relapsed brain tumors.

PATIENTS AND METHODS

The files of 14 children treated at our hospital between 2005 and 2010 with the diagnoses of relapsed brain tumors were reviewed for pathological characteristics, treatment results, and outcomes.

RESULTS

The median age at relapse was 8 years (range, 1.08-23; F/M, 5/9). Diagnoses included medulloblastoma (n = 5), atypical teratoid rhabdoid tumor (n = 2), ependymoma (n = 2), glioneuronal tumor (n = 1), malignant neoplasm (n = 1), pontine glioma (n = 1), astrocytoma grade III (n = 1), and glioblastoma multiforme (n = 1). All patients except the one with pontine glioma had undergone surgical resection, and all had prior adjuvant chemotherapy. Twelve out of 14 patients had received radiotherapy. The median number of temozolomide courses was 5.0 (range, 1-24). Objective response rate in our patients was 35.7% (three complete responses, one partial response, and one minor response). Stable disease achieved in 14.3% of patients and 50% had progressive disease. Median survival time was 8 months (range, 1-55). At the end of the study, three patients were alive. Hematological toxicity was seen in 30.8% of all courses.

CONCLUSIONS

Relapsed brain tumors in childhood have an unfavorable prognosis. These data suggest that temozolomide might be an active agent against recurrent medulloblastoma. Although overall objective response rate was low, further multicentric studies with temozolomide may be warranted in children with recurrent brain tumors.

Atypical teratoid/rhabdoid tumors in adults: a case report and treatment-focused review

Atypical teratoid/rhabdoid tumor is predominantly a childhood tumor and has only been rarely reported in adults; therefore, treatment regimens are often extrapolated from the pediatric experience. Typically, children are treated with craniospinal radiation therapy which is often followed by systemic chemotherapy. Employing pediatric regimens to treat this tumor in adult patients poses a particular risk for myelosuppression, as the prescribed doses in pediatric protocols exceed those tolerated by adults, and conventional craniospinal radiation can be associated with prolonged myelotoxicity and a depletion of the bone marrow reserve in vertebrae of adults. Here we present a case of a woman with a pineal region atypical teratoid/rhabdoid tumor, an unusual adult cancer presenting in an atypical location. This is followed by a review of the disease in adult patients with an emphasis on treatment and suggestions to minimize myelotoxicity.

Central nervous system penetration and enhancement of temozolomide activity in childhood medulloblastoma models by poly(ADP-ribose) polymerase inhibitor AG-014699

BACKGROUND

Temozolomide shows activity against medulloblastoma, the most common malignant paediatric brain tumour. Poly(ADP-ribose) polymerase (PARP) inhibitors enhance temozolomide activity in extracranial adult and paediatric human malignancies.

METHODS

We assessed the effect of AG-014699, a clinically active PARP inhibitor, on temozolomide-induced growth inhibition in human medulloblastoma models. Pharmacokinetic, pharmacodynamic and toxicity assays were performed in tumour-bearing mice.

RESULTS

Sensitivity to temozolomide in vitro was consistent with methylguanine methyltransferase (MGMT) and DNA mismatch repair (MMR) status; MGMT(+) MMR(+) D384Med cells (temozolomide GI(50)=220 μM), representative of most primary medulloblastomas, were sensitised fourfold by AG-014699; MGMT⁻ MMR(+) D425Med cells were hypersensitive (GI(50)=9 μM) and not sensitised by AG-014699, whereas MGMT(+) MMR⁻ temozolomide-resistant D283Med cells (GI₅₀=807 μM) were sensitised 20-fold. In xenograft models, co-administration of AG-014699 produced an increase in temozolomide-induced tumour growth delay in D384Med xenografts. Consistent with the in vitro data, temozolomide caused complete tumour regressions of D425Med xenografts, whereas D283Med xenografts were relatively resistant. AG-014699 was not toxic, accumulated and reduced PARP activity ≥75% in xenograft and brain tissues.

CONCLUSION

We show for the first time central nervous system penetration and inhibition of brain PARP activity by AG-014699. Taken together with our in vitro chemosensitisation and toxicity data, these findings support further evaluation of the clinical potential of AG-014699-temozolomide combinations in intra-cranial malignancies.