Temozolomide in the treatment of children with newly diagnosed diffuse intrinsic pontine gliomas: a report from the Children's Oncology Group

A phase 2 study of pegylated interferon α-2b (PEG-Intron(®)) in children with diffuse intrinsic pontine glioma

BACKGROUND

Interferon-α is a cytokine that has demonstrated activity in patients with supratentorial gliomas, but its ideal dose and schedule of administration is unknown. Studies suggest that low-dose, continuous exposure is more efficacious than intermittent, high doses. The authors performed a phase 2 study of recombinant interferon α-2b with monomethoxy polyethylene glycol (PEG-Intron(®)) in children with diffuse intrinsic pontine glioma (DIPG), a population with dismal survival despite decades of clinical investigation. The primary objective was to compare 2-year survival with a historic cohort that received radiation therapy alone.

METHODS

Patients received weekly subcutaneous PEG-Intron(®) at a dose of 0.3 μg/kg beginning 2 to 10 weeks after the completion of radiation therapy until they developed disease progression. Patients were evaluated clinically and radiographically at regular intervals. Serum and urine were assayed for biomarkers before each cycle. Quality-of-life (QOL) evaluations were administered at baseline and before every other cycle of therapy to the parents of patients ages 6 to 18 years.

RESULTS

Thirty-two patients (median age, 5.3 years; range, 1.8-14.8 years) were enrolled and received a median of 7 cycles of therapy (range, from 1 cycle to ≥70 cycles). PEG-Intron(®) was well tolerated, and no decrease in QOL scores was noted in the subset of patients tested. The 2-year survival rate was 14%, which was not significantly improved compared with the historic cohort. However, the median time to progression was 7.8 months, which compared favorably with recent trials reporting a time to progression of 5 months in a similar population.

CONCLUSIONS

Although low-dose PEG-Intron(®) therapy did not significantly improve 2-year survival in children with DIPG compared with an historic control population, it did delay the time to progression.

Brain stem gliomas: a clinicopathological study from a single cancer center

Brain stem gliomas (BSG) are rare tumors occurring predominantly in childhood. They are mostly of astrocytic origin and are divided into infiltrative versus circumscribed types, with different prognoses. The diagnosis is mainly based on MRI findings, and biopsy is rarely performed. This is a retrospective study of BSG with available biopsies diagnosed at our center over 6-year period. Fifteen cases were identified, with a predominance of females. The median age was 7 years, and the mean duration of symptoms was <6 weeks in 58.3% (n = 7) of cases. MRI was typical of diffuse pontine gliomas in 64.3% (n = 9) of cases. Radiotherapy was the commonest modality of treatment, and the median overall survival was 21.7 months. Twelve cases were consistent with infiltrative astrocytoma of various grades (2 grade II, 7 grade III and 3 grade IV). Entrapped normal neurons and mitosis were the commonest findings indicating infiltrative growth and high grade, respectively, and those correlated significantly with immunostaining for neurofilament protein and Ki-67 of ≥3%. Overall survival correlated only with the duration of symptoms and tumor grade on biopsies. A limited panel of immunostains might be useful in undetermined cases to decide on the growth pattern and grade.

Pediatric neuro-oncology: current status and future directions

Tumors of the central nervous system (CNS) are the most common solid malignancies in childhood and are the leading cause of cancer-related death in this age group. While an ongoing improvement in overall prognosis has been achieved in the last few decades, current therapeutic approaches still confer significant morbidities, especially for the very young. The traditional strategies of surgery, radiotherapy and conventional cytotoxic chemotherapy need to be further refined while newer approaches, including molecularly targeted agents, hold the promise of better responses, improved outcomes and reduced toxicities. This article discusses treatment standards, the focus of current clinical investigations and the future promise of novel, biologically based approaches for the most common pediatric CNS tumors: primitive neuroectodermal tumors including medulloblastomas, ependymomas and astrocytomas (both low-grade and high-grade glioma).

Temozolomide or bevacizumab for spinal cord high-grade gliomas

High-grade gliomas of the spinal cord are rare tumors, traditionally managed with surgery and radiotherapy. Once patients fail standard treatment, many receive some chemotherapy, although the data supporting such is limited. We reviewed our experience treating high-grade gliomas of the spinal cord with standard intracranial regimens including temozolomide and bevacizumab. Outcomes investigated include radiographic response, clinical response, progression-free survival, and overall survival. We identified eight patients who were treated with temozolomide and six who were treated with bevacizumab. Temozolomide was administered to three patients at initial diagnosis and five patients at recurrence after failing prior radiotherapy. For the recurrent patients, the median time-to-progression was 6.6 months (range 1-40 months) and the median overall survival from initiation of temozolomide was 16.6 months (range 1.2-64.5 months). We identified six patients who received bevacizumab at the time of recurrence. MRI demonstrated a partial response in five patients which also correlated with clinical improvement. The median time to progression was 20.7 months (range 3.3-29.9 months) and median overall survival was 22.8 months (range 3.3-31.8 months). This retrospective review suggests that temozolomide and bevacizumab may be beneficial in spinal cord high-grade gliomas. The compact architecture of the spinal cord makes bevacizumab a particularly appealing agent due to the drug's effect on peritumoral edema and mass effect.

High-grade gliomas in children

High-grade gliomas (HGGs) are malignant tumors and typically include glioblastoma multiforme and anaplastic astrocytoma subtypes. Brainstem gliomas and ependymomas are separate entities with respect to clinical presentation, treatment, prognosis, and outcome in comparison with supratentorial HGGs. In children, these tumors account for 3% to 7% of newly diagnosed brain tumors and 20% of all diagnoses of pediatric supratentorial brain tumors. These neoplasms are highly proliferative and mitotically active and of glial origin. This article reviews clinical, diagnostic, and pathologic features of HGG and current treatments and potential future therapies specific to pediatric patients with HGGs.

Paediatric and adult malignant glioma: close relatives or distant cousins?

Gliomas in children differ from their adult counterparts by their distribution of histological grade, site of presentation and rate of malignant transformation. Although rare in the paediatric population, patients with high-grade gliomas have, for the most part, a comparably dismal clinical outcome to older patients with morphologically similar lesions. Molecular profiling data have begun to reveal the major genetic alterations underpinning these malignant tumours in children. Indeed, the accumulation of large datasets on adult high-grade glioma has revealed key biological differences between the adult and paediatric disease. Furthermore, subclassifications within the childhood age group can be made depending on age at diagnosis and tumour site. However, challenges remain on how to reconcile clinical data from adult patients to tailor novel treatment strategies specifically for paediatric patients.

Treatment outcomes in black and white children with cancer: results from the SEER database and St Jude Children's Research Hospital, 1992 through 2007

PURPOSE

Treatment outcome for black patients with cancer has been significantly worse than for their white counterparts. We determined whether recent improved treatment had narrowed the gap in outcome between black and white pediatric patients.

PATIENTS AND METHODS

In a parallel comparison, we analyzed survival by disease category between black and white patients with childhood cancer registered in one of the 17 cancer registries of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program or treated at St Jude Children's Research Hospital, which provides comprehensive treatment to all patients regardless of their ability to pay, from 1992 to 2000 and from 2001 to 2007.

RESULTS

Analysis of the SEER data indicated that in both study periods, black patients had significantly poorer rates of survival than did white patients, with the exception of a few types of cancer. Despite significantly improved treatment outcomes for patients who were treated from 2001 to 2007, the racial difference in survival has actually widened for acute myeloid leukemia and neuroblastoma. By contrast, in the cohorts treated at St Jude Children's Research Hospital, there were no significant differences in survival between black and white patients in either study period, regardless of the cancer type. Importantly, the outcome of treatment for acute lymphoblastic leukemia, acute myeloid leukemia, and retinoblastoma has improved in parallel for both races during the most recent study period.

CONCLUSION

With equal access to comprehensive treatment, black and white children with cancer can achieve the same high cure rates.

Targeted therapy for BRAFV600E malignant astrocytoma

PURPOSE

Malignant astrocytomas (MA) are aggressive central nervous system tumors with poor prognosis. Activating mutation of BRAF (BRAF(V600E)) has been reported in a subset of these tumors, especially in children. We have investigated the incidence of BRAF(V600E) in additional pediatric patient cohorts and examined the effects of BRAF blockade in preclinical models of BRAF(V600E) and wild-type BRAF MA.

EXPERIMENTAL DESIGN

BRAF(V600E) mutation status was examined in two pediatric MA patient cohorts. For functional studies, BRAF(V600E) MA cell lines were used to investigate the effects of BRAF shRNA knockdown in vitro, and to investigate BRAF pharmacologic inhibition in vitro and in vivo.

RESULTS

BRAF(V600E) mutations were identified in 11 and 10% of MAs from two distinct series of tumors (six of 58 cases total). BRAF was expressed in all MA cell lines examined, among which BRAF(V600E) was identified in four instances. Using the BRAF(V600E)-specific inhibitor PLX4720, pharmacologic blockade of BRAF revealed preferential antiproliferative activity against BRAF(V600E) mutant cells in vitro, in contrast to the use of shRNA-mediated knockdown of BRAF, which inhibited cell growth of glioma cell lines regardless of BRAF mutation status. Using orthotopic MA xenografts, we show that PLX4720 treatment decreases tumor growth and increases overall survival in mice-bearing BRAF(V600E) mutant xenografts, while being ineffective, and possibly tumor promoting, against xenografts with wild-type BRAF.

CONCLUSIONS

Our results indicate a 10% incidence of activating BRAF(V600E) among pediatric MAs. With regard to implications for therapy, our results support evaluation of BRAF(V600E)-specific inhibitors for treating BRAF(V600E) MA patients.

A phase II study of O6-benzylguanine and temozolomide in pediatric patients with recurrent or progressive high-grade gliomas and brainstem gliomas: a Pediatric Brain Tumor Consortium study

To estimate the sustained (≥8 weeks) objective response rate in pediatric patients with recurrent or progressive high-grade gliomas (HGG, Stratum A) or brainstem gliomas (BSG, Stratum B) treated with the combination of O6-benzylguanine (O6BG) and temozolomide(®) (TMZ). Patients received O6BG 120 mg/m(2)/d IV followed by TMZ 75 mg/m(2)/d orally daily for 5 consecutive days of each 28-day course. The target objective response rate to consider the combination active was 17%. A two-stage design was employed. Forty-three patients were enrolled; 41 were evaluable for response, including 25 patients with HGG and 16 patients with BSG. The combination of O6BG and TMZ was tolerable, and the primary toxicities were myelosuppression and gastrointestinal symptoms. One sustained (≥8 weeks) partial response was observed in the HGG cohort; no sustained objective responses were observed in the BSG cohort. Long-term (≥6 courses) stable disease (SD) was observed in 4 patients in Stratum A and 1 patient in Stratum B. Of the 5 patients with objective response or long-term SD, 3 underwent central review with 2 reclassified as low-grade gliomas. The combination of O6BG and TMZ did not achieve the target response rate for activity in pediatric patients with recurrent or progressive HGG and BSG.

Treatment of high-grade glioma in children and adolescents

Pediatric high-grade gliomas (HGGs)--including glioblastoma multiforme, anaplastic astrocytoma, and diffuse intrinsic pontine glioma--are difficult to treat and are associated with an extremely poor prognosis. There are no effective chemotherapeutic regimens for the treatment of pediatric HGG, but many new treatment options are in active investigation. There are crucial molecular differences between adult and pediatric HGG such that results from adult clinical trials cannot simply be extrapolated to children. Molecular markers overexpressed in pediatric HGG include PDGFRα and P53. Amplification of EGFR is observed, but to a lesser degree than in adult HGG. Potential molecular targets and new therapies in development for pediatric HGG are described in this review. Research into bevacizumab in pediatric HGG indicates that its activity is less than that observed in adult HGG. Similarly, tipifarnib was found to have minimal activity in pediatric HGG, whereas gefitinib has shown greater effects. After promising phase I findings in children with primary CNS tumors, the integrin inhibitor cilengitide is being investigated in a phase II trial in pediatric HGG. Studies are also ongoing in pediatric HGG with 2 EGFR inhibitors: cetuximab and nimotuzumab. Other novel treatment modalities under investigation include dendritic cell-based vaccinations, boron neutron capture therapy, and telomerase inhibition. While the results of these trials are keenly awaited, the current belief is that multimodal therapy holds the greatest promise. Research efforts should be directed toward building multitherapeutic regimens that are well tolerated and that offer the greatest antitumor activity in the setting of pediatric HGG.

Radiotherapy with concurrent and adjuvant temozolomide in children with newly diagnosed diffuse intrinsic pontine glioma

The purpose of this study is to evaluate the efficacy and toxicity of radiation therapy (RT) with concurrent temozolomide (TMZ) chemotherapy followed by adjuvant TMZ in children with diffuse intrinsic pontine glioma (DIPG). Newly diagnosed patients younger than 18 years with histologically proven DIPG were treated with focal radiotherapy to a dose of 54 Gy in 30 fractions along with concurrent daily TMZ (75 mg/m(2)/day). Four weeks after completing the initial RT-TMZ schedule, adjuvant TMZ (200 mg/m(2)/day, days 1-5) was given every 28 days up to six cycles. Responses/progressions were assessed by clinical and 2-monthly MRI follow-up studies. Between September 2005 and September 2009, 21 patients with newly diagnosed histologically confirmed DIPG were eligible for this study. Median age at diagnosis was 6.4 years (range 4-16 years). At last update in August 2010, 17 children have died, 1 child was alive with progressive disease and 3 with stable disease. Metastatic relapse was documented in the cerebral site in two patients and in spinal cord in two cases. The median time to progression was 7.5 months (range 28 days-14.5 months) and the median survival was 11.7 months (range 26 days-17.5 months). The 1-year PFS and the 1-year OS were 33 and 50%, respectively. Five patients presented radiological findings compatible with pseudoprogression during the treatment. Haematological toxicity (Grade III/IV thrombocytopenia and leucopenia) was the most commonly found and led to dose reductions of TMZ in 58% of the patients. TMZ with radiation therapy has not yielded any significant improvement in outcome of children with DIPG and is associated with higher toxicity compared with radiotherapy alone. Novel treatment modalities are needed to improve the outcome of these patients.

Multidisciplinary management of childhood brain tumors: a review of outcomes, recent advances, and challenges

OBJECT

Brain tumors are the most common category of childhood solid tumors. In the 1970s and 1980s, treatment protocols for benign tumors focused almost exclusively on surgery, with radiation treatment as a salvage modality, whereas the management of malignant tumors employed a combination of surgery, radiation therapy, and chemotherapy, with therapeutic approaches such as "8-in-1" chemotherapy often applied across histological tumor subsets that are now recognized to be prognostically distinct. During the ensuing years, treatment has become increasingly refined, based on clinical and, more recently, molecular factors, which have supported risk-adapted treatment stratification. The goal of this report is to provide an overview of recent progress in the field.

METHODS

A review of the literature was undertaken to examine recent advances in the management of the most common childhood brain tumor subsets, and in particular to identify instances in which molecular categorization and treatment stratification offer evidence or promise for improving outcome.

RESULTS

For both medulloblastomas and infant tumors, refinements in clinical and molecular stratification have already facilitated efforts to achieve risk-adapted treatment planning. Current treatment strategies for children with these tumors focus on improving outcome for tumor subsets that have historically been relatively resistant to therapy and reducing treatment-related sequelae for children with therapy-responsive tumors. Recent advances in molecular categorization offer the promise of further refinements in future studies. For children with ependymomas and low-grade gliomas, clinical risk stratification has facilitated tailored approaches to therapy, with improvement of disease control and concomitant reduction in treatment sequelae, and recent discoveries have identified promising therapeutic targets for molecularly based therapy. In contrast, the prognosis remains poor for children with diffuse intrinsic pontine gliomas and other high-grade gliomas, despite recent identification of biological correlates of tumor prognosis and elucidation of molecular substrates of tumor development.

CONCLUSIONS

Advances in the clinical and molecular stratification for many types of childhood brain tumors have provided a foundation for risk-adapted treatment planning and improvements in outcome. In some instances, molecular characterization approaches have also yielded insights into new therapeutic targets. For other tumor types, outcome remains discouraging, although new information regarding the biological features critical to tumorigenesis are being translated into novel therapeutic approaches that hold promise for future improvements.