Differential responsiveness among "high risk" pediatric brain tumors in a pilot study of dose-intensive induction chemotherapy

Preradiation Chemotherapy for Adult High-risk Medulloblastoma: A Trial of the ECOG-ACRIN Cancer Research Group (E4397)

OBJECTIVES

To assess the long-term outcomes and objective response (OR) to preradiation chemotherapy and radiation in adult high-risk medulloblastoma.

MATERIALS AND METHODS

In this prospective phase II trial, adults with high-risk medulloblastoma were treated with 3 cycles of preradiation cisplatin, etoposide, cyclophosphamide, and vincristine followed by craniospinal radiation (CSI). OR, progression-free survival (PFS), overall survival (OS), and toxicities were assessed.

RESULTS

Eleven patients were enrolled over a 6-year period. Six (55%) had subarachnoid metastases. Two (18%) had an OR to preradiation chemotherapy. Two (18%) progressed while on chemotherapy. Completion of CSI was not compromised. The OR rate after chemotherapy and radiation was 45% (5/11). Nonevaluable patients at both time-points weakened the response data conclusions. Median PFS was 43.8 months. Five-year PFS was 27%. Five-year OS was 55%. Nonmetastatic (M0) and metastatic (M+) patients had similar outcomes.

CONCLUSIONS

The OR to this preradiation chemotherapy regimen is lower than anticipated from the adult and pediatric literature raising a question about comparative efficacy of chemotherapy in different age groups. The OS achieved is similar to retrospective adult series, but worse than pediatric outcomes. Although this regimen can be administered without compromising delivery of CSI, our results do not provide support for the use of this neoadjuvant chemotherapy for adult medulloblastoma.

A WEE1 Inhibitor Analog of AZD1775 Maintains Synergy with Cisplatin and Demonstrates Reduced Single-Agent Cytotoxicity in Medulloblastoma Cells

The current treatment for medulloblastoma includes surgical resection, radiation, and cytotoxic chemotherapy. Although this approach has improved survival rates, the high doses of chemotherapy required for clinical efficacy often result in lasting neurocognitive defects and other adverse events. Therefore, the development of chemosensitizing agents that allow dose reductions of cytotoxic agents, limiting their adverse effects but maintaining their clinical efficacy, would be an attractive approach to treat medulloblastoma. We previously identified WEE1 kinase as a new molecular target for medulloblastoma from an integrated genomic analysis of gene expression and a kinome-wide siRNA screen of medulloblastoma cells and tissue. In addition, we demonstrated that WEE1 prevents DNA damage-induced cell death by cisplatin and that the WEE1 inhibitor AZD1775 displays synergistic activity with cisplatin. AZD1775 was developed as a WEE1 inhibitor from an initial hit from a high-throughput screen. However, given the lack of structure-activity data for AZD1775, we developed a small series of analogs to determine the requirements for WEE1 inhibition and further examine the effects of WEE1 inhibition in medulloblastoma. Interestingly, the compounds that inhibited WEE1 in the same nanomolar range as AZD1775 had significantly reduced single-agent cytotoxicity compared with AZD1775 and displayed synergistic activity with cisplatin in medulloblastoma cells. The potent cytotoxicity of AZD1775, unrelated to WEE1 inhibition, may result in dose-limiting toxicities and exacerbate adverse effects; therefore, WEE1 inhibitors that demonstrate low cytotoxicity could be dosed at higher concentrations to chemosensitize the tumor and potentiate the effect of DNA-damaging agents such as cisplatin.

The effect of alpha-v integrin inhibition on the malignant characteristics of medulloblastoma

OBJECT

Hypoxia induces an aggressive phenotype in some brain tumors in part due to hypoxia-inducible factor-1α (HIF-1α) and integrin expression. The importance of hypoxia in medulloblastoma is unclear and the interaction of HIF-1α and c-Myc in medulloblastoma has not been explored. The objective of this study was to determine if hypoxia induces an aggressive phenotype in human medulloblastoma cells that constitutively express high (D283 Med) or low (DAOY) levels of c-Myc and to determine if blocking α(v) integrins with the monoclonal antibody intetumumab inhibits hypoxia-induced cellular stress responses.

METHODS

Cells were grown at 21% and 1% O(2) and in the presence or absence of intetumumab. Measures of malignancy evaluated included cell proliferation, cell migration, and expression of vascular endothelial growth factor (VEGF), α(v) integrins, HIF-1α, and c-Myc.

RESULTS

Both cell lines robustly expressed α(v) integrins. Hypoxic DAOY cells showed significantly increased proliferation compared with normoxic controls (p < 0.05), whereas D283 Med cells did not. Both cell lines exhibited a dose-dependent decrease in proliferation when treated with intetumumab (p < 0.05). Hypoxia did not increase DAOY migration, but intetumumab significantly inhibited migration at both oxygen conditions (p < 0.05). Intetumumab significantly decreased VEGF levels in DAOY cells at both oxygen conditions (p < 0.05) and in normoxic D283 cells (p < 0.01). Neither cell line demonstrated increased HIF-1α expression in response to hypoxia. However, hypoxic D283 Med cells grown in the presence of intetumumab demonstrated significantly decreased c-Myc expression (p < 0.05).

CONCLUSIONS

Hypoxia did not clearly induce a more aggressive phenotype in medulloblastoma cells. Despite this result, intetumumab decreased medulloblastoma cell proliferation and migration and variably decreased VEGF and c-Myc expression in hypoxic conditions. Targeting α(v) integrins represents a promising potential adjuvant modality in the treatment of medulloblastoma, particularly subtypes that metastasize and overexpress VEGF and c-Myc.

The impact of radiotherapy fields in the treatment of patients with choroid plexus carcinoma

PURPOSE

To perform a comprehensive literature review and analysis of cases dealing with choroid plexus carcinoma (CPC) to determine the optimal radiotherapy (RT) treatment field.

METHODS AND MATERIALS

A PubMed search of English language articles from 1979 to 2008 was performed, yielding 33 articles with 56 patients who had available data regarding RT treatment field. The median age at diagnosis was 2.7 years (range, 1 month-53 years). Of 54 patients with data regarding type of surgery, 21 (38.9%) had complete resection. Chemotherapy was delivered to 27 (48%) as part of initial therapy. The RT treatment volume was the craniospinal axis in 38 (68%), whole brain in 9 (16%), and tumor/tumor bed in 9 (16%). Median follow-up for surviving patients was 40 months.

RESULTS

The 5-year overall survival and progression-free survival (PFS) rates were 59.5% and 37.2%, respectively. Complete resection (p = 0.035) and use of craniospinal irradiation (CSI; p = 0.025) were found to positively affect PFS. The 5-year PFS for patients who had CSI vs. whole brain and tumor/tumor bed RT were 44.2% and 15.3%. For the 19 patients who relapsed, 9 (47%) had a recurrence in the RT field, 6 (32%) had a recurrence outside the RT field, and 4 (21%) had a recurrence inside and outside the irradiated field.

CONCLUSION

Patients with CPC who received CSI had better PFS compared with those receiving less than CSI. This study supports the use of CSI in the multimodality management of patients with CPC.

New concepts in the treatment of brain tumors in very young children

The treatment of brain tumors in infants (children <3 years of age) in the last 15-20 years has been a special field of interest for clinical investigation and research, since infants affected by brain tumors are an ideal experimental group of patients. New treatment strategies (conventional, myeloablative and intraventricular chemotherapy) have been tested on these patients in an effort to avoid or delay conventional irradiation. The amazing amount of knowledge that has been acquired from neuropathological and biological studies, as well as from the first generation treatment baby protocols, which were designed between 1985 and 2000, is now leading to a new approach whereby treatment strategies are tailored to the patient's clinicopathological features.