Chemotherapy for medulloblastomas and primitive neuroectodermal tumors

Using Pharmacology to Squeeze the Life Out of Childhood Leukemia, and Potential Strategies to Achieve Breakthroughs in Medulloblastoma Treatment

Eliminating cancer was once thought of as a war. This analogy is still apt today; however, we now realize that cancer is a much more formidable enemy than scientists originally perceived, and in some cases, it harbors a profound ability to thwart our best efforts to defeat it. However, before we were aware of the complexity of cancer, chemotherapy against childhood acute lymphoblastic leukemia (ALL) was successful because it applied the principles of pharmacology. Herein, we provide a historic perspective of the experience at St. Jude Children's Research Hospital. In 1962, when the hospital opened, fewer than 3% of patients experienced durable cure. Through judicious application of pharmacologic principles (e.g., combination therapy with agents using different mechanisms of action) plus appropriate drug scheduling, dosing, and pharmacodynamics, the survival of patients with ALL now exceeds 90%. We contrast this approach to treating ALL with the contemporary approach to treating medulloblastoma, in which genetics and molecular signatures are being used to guide the development of more-efficacious treatment strategies with minimal toxicity. Finally, we highlight the emerging technologies that can sustain and propel the collaborative efforts to squeeze the life out of these cancers. SIGNIFICANCE STATEMENT: Up until the early 1960s, chemotherapy for childhood acute lymphoblastic leukemia was mostly ineffective. This changed with the knowledge and implementation of rational approaches to combination therapy. Although the therapeutics of brain cancers such as medulloblastoma are not as refined (in part because of the blood-brain barrier obstacle), recent extraordinary advances in knowledge of medulloblastoma pathobiology has led to innovations in disease classification accompanied with strategies to improve therapeutic outcomes. Undoubtedly, additional novel approaches, such as immunological therapeutics, will open new avenues to further the goal of taming cancer.

Treatment of pediatric average-risk medulloblastoma using craniospinal irradiation less than 2500 cGy and chemotherapy: single center experience in Korea

BACKGROUND

Although craniospinal irradiation (CSI) of 2340 cGy plus tumor booster with chemotherapy have been established as a standard treatment of childhood average-risk (AvR) medulloblastoma (MBL) in Western counties, there are a few recent reports in outcomes of AvR MBL using this strategy in Korean and other Asian children. We investigated the outcome of the Korean children with AvR MBL who were treated with CSI <2500 cGy and chemotherapy.

METHODS

Between January 2001 and December 2010, clinical characteristics and outcomes of 42 patients who were diagnosed with AvR MBL postoperatively and treated with radiation including CSI <2500 cGy and chemotherapy in Seoul National University Children's Hospital were analyzed.

RESULTS

Their median age was 9 years (range: 3-18.8), and 29 were male. Histological subtypes were classic type in 28 patients, nodular/desmoplastic in 7, and large cell/anaplastic (LCA) in 7. All the patients received adjuvant radiotherapy (CSI with median 2340 cGy and booster) and multiagent chemotherapy as the first-line treatment. With a median follow-up of 54 months, 12 patients experienced relapse or progression of the tumor. The 3- and 5-year disease-free survival (DFS) rates were 78.0%±6.5% and 75.0%±6.9%, respectively, and overall survival (OS) rates were 85.3%±5.6% and 76.8%±6.9%, respectively. The LCA subtype was associated with poorer DFS (P=0.023) and OS (P=0.008), compared with non-LCA subtypes.

CONCLUSIONS

The outcomes of children and adolescents with AvR MBL treated with radiation including CSI <2500 cGy and chemotherapy, are compatible to those in Western countries; however, the LCA subtype has a poor outcome with this strategy.

Medulloblastoma/Primitive neuroectodermal tumor and germ cell tumors: the uncommon but potentially curable primary brain tumors

This article presents an overview of medulloblastomas, central nervous system primitive neuroectodermal tumors, and germ cell tumors for the practicing oncologist. Discussion includes the definition of these tumors, histopathologic findings, molecular and genetic characteristics, prognoses, and evolution of treatment.

Adult neuroectodermal tumors of posterior fossa (medulloblastoma) and of supratentorial sites (stPNET)

Medulloblastoma and supratentorial primitive neuroectodermal tumors are rare diseases in adults. Due to this rarity, few prospective clinical trials have been conducted on medulloblastoma in adults, investigations being based exclusively on retrospective studies; the populations considered in literature are small, and the different treatments given span decades, during which diagnostic procedures, neurosurgical skills and radiotherapy techniques have changed. Unlike pediatric patients, adult medulloblastoma patients have been treated according to risk-adapted therapeutic strategies in only a few series and despite risk-tailored treatments, 20-30% of patients experience recurrence. Although patients could respond to second line treatments, the prognosis of relapsed patients remains dismal. An important challenge for the future will be the biological characterization of medulloblastoma, with the identification of specific genetic patterns of patients with a better or a worse prognosis.

Timing of radiation in children with medulloblastoma/PNET

BACKGROUND

To evaluate the importance of timing of radiation therapy in children with PNET/medulloblastoma, treated at the Brazilian National Cancer Institute (INCA).

PROCEDURE

The records of 101 children with confirmed diagnosis of medulloblastoma were retrospectively reviewed. Patients had a median follow-up of 48 months (0.5-241 months). The age varied from 0.8 to 17.5 years (median: 7.6 years) and 21.7% were 3 years old or younger.

RESULTS

According to the data collected from patients that received treatment for medulloblastoma from 1983 to 2001, the overall survival (OS) rate was 53% and the Disease Free Survival (DFS) rate was 40%. Multivariate analysis showed that under age 3 years, presence of neoplasic cells in the cerebrospinal fluid (CSF) at presentation or subtotal tumor resection resulted in a worse OS. The patients that received a biological effective dose (BED) greater than 44 Gy10 had better prognosis. Two-thirds of the patients had complete response after the initial treatment. Among them, 50% (34 patients) recurred, and of those 34 patients, 42% of them (14 patients) had recurrence in the posterior fossa.

CONCLUSION

Surgery with total resection of the tumor and absence of neoplasic cells in the CSF are effective predictors of better OS. Radiotherapy was more effective when a BED was greater than 44 Gy10.

Childhood pineoblastoma: experiences from the prospective multicenter trials HIT-SKK87, HIT-SKK92 and HIT91

OBJECTIVE

To analyze the outcome of children with pineoblastoma (PB), treated within the prospective multicenter trials HIT-SKK87, HIT-SKK92 and HIT91 of German-speaking countries.

PATIENTS

We report on 11 children suffering from PB. Five children younger than 3 years of age received chemotherapy after surgery until eligible for radiotherapy (HIT-SKK87 and HIT-SKK92). Five of six children older than 3 years were treated after surgery with immediate chemotherapy and craniospinal irradiation, and one child received maintenance chemotherapy after postoperative radiotherapy (HIT91).

RESULTS

Five of the six older children are still alive in continuous complete remission (CCR) with a median overall survival (OS) and progression free survival (PFS) of 7.9 years. Five of these six HIT91 patients responded to postoperative chemotherapy and radiotherapy. The only patient with tumor progression during initial chemotherapy achieved complete remission with radiotherapy and is alive. In contrast, all five young children died of tumor progression after a median OS of 0.9 years (PFS 0.6 years). They had either metastatic disease (M1) and/or postoperative residual tumor. Response to postoperative chemotherapy was lower than in the older age group, and only one of these children received radiotherapy.

CONCLUSIONS

Combined chemotherapy and radiotherapy were feasible and effective in the older age group, leading to prolonged remissions in five of six children. Tumor biology may be more aggressive in younger children with PB, who presented more frequently with high-risk features at diagnosis and had poorer response rates to neoadjuvant postoperative chemotherapy. More intensified treatment regimens may be needed for young children with PB.

Apurinic/apyrimidinic endonuclease activity is associated with response to radiation and chemotherapy in medulloblastoma and primitive neuroectodermal tumors

PURPOSE

Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers resistance to radiation- and alkylator-induced cytotoxic abasic sites in human cells. We assayed apurinic/apyrimidinic endonuclease activity in medulloblastomas and primitive neuroectodermal tumors (PNET) to establish correlates with tumor and patient characteristics and with response to adjuvant radiation plus multiagent chemotherapy.

EXPERIMENTAL DESIGN

Ap endo activity was assayed in 52 medulloblastomas and 10 PNETs from patients 0.4 to 21 years old. Ape1/Ref-1, the predominant human Ap endo activity, was measured in 42 medulloblastomas by immunostaining. Cox proportional hazards regression models were used to analyze the association of activity with time to tumor progression (TTP).

RESULTS

Tumor Ap endo activity varied 180-fold and was significantly associated with age and gender. Tumor Ape1/Ref-1 was detected almost exclusively in nuclei. In a multivariate model, with Ap endo activity entered as a continuous variable, the hazard ratio for progression after adjuvant treatment in 46 medulloblastomas and four PNETs increased by a factor of 1.073 for every 0.01 unit increase in activity (P < or = 0.001) and was independent of age and gender. Suppressing Ap endo activity in a human medulloblastoma cell line significantly increased sensitivity to 1,3-bis(2-chlororethyl)-1-nitrosourea and temozolomide, suggesting that the association of tumor activity with TTP reflected, at least in part, abasic site repair.

CONCLUSIONS

Our data (a) suggest that Ap endo activity promotes resistance to radiation plus chemotherapy in medulloblastomas/PNETs, (b) provide a potential marker of treatment outcome, and (c) suggest clinical use of Ap endo inhibitors to overcome resistance.

Review of the prognostic factors in medulloblastoma of children and adults

Medulloblastoma (MB) is rare in adults, accounting for 1% of all primary tumours of the central nervous system (CNS). Based on the assumption that the disease pattern in adults is similar to that in children, adults with medulloblastoma are treated using paediatric protocols. Thanks to progress made in recent years, long-term survival is now possible, with overall ranging from 50 to 60% at 5 years and 40 to 50% at 10 years. However, effective therapy may have devastating long-term side effects, including neuro-psychic and neuro-endocrine sequelae and cognitive dysfunction, especially in young adults. Great interest has been expressed in new biological and molecular prognostic factors, which, combined with clinical variables, may allow a more satisfactory stratification of patients.

Analysis of chromosome abnormalities by comparative genomic hybridization in malignant peripheral primitive neuroectodermal tumor of the ovary

OBJECTIVE

Malignant primitive neuroectodermal tumor (PNET) originating from the ovary rather than from the central nervous system is extremely rare. The aim of this study is to demonstrate the chromosomal abnormalities in a case of peripheral primitive neuroectodermal tumor (PPNET) arising from the ovary of a girl.

METHODS

The 13-year-old girl underwent exploratory laparotomy because of a huge pelvic tumor in lower abdomen and pelvis. She underwent removal of ovaries, tubes, omentum, peritoneal nodules, and portion of urinary bladder. Tumor specimens were sent for pathology, short-term tissue culture, and for storage in deep freezer for laboratory studies. Immunohistochemical stainings of the tumor with antibodies against O-13 (MIC/CD99), NSE, GFAP, S-100, cytokeratin AE1/AE3, desmin, NF, and AFP were performed. Short-term cell culture of fresh tumor was done for analysis of chromosomal aberrations by the technique of comparative genomic hybridization (CGH). Names of specific genes corresponding to the losses or gains on gene map loci were identified from OMIM (Online Mendelian Inheritance in Man) of the NCBI website,. The overexpressions of N-myc and EGFR as well as underexpressions of Rb and ARHI were detected by RT-PCR analysis. The patient expired 17 months later despite of chemotherapy, repeated surgery, and radiation therapy.

RESULT

The histopathology of the specimens revealed malignant neuroectodermal tumor, involving ovaries, tubes, bladder, omentum, and peritoneum. Immunohistochemical stainings of PPNET of the ovary showed positive reaction for O-13 (MIC2/CD99) and NSE, but negative for GFAP, S-100, cytokeratin AE1/AE3, desmin, NF, and AFP. Analysis of CGH revealed multiple chromosomal abnormalities including losses of chromosomes in 1p, 1q, 4q, 6p, 6q, 7q, 8q, 13q, and 19q; as well as gains of chromosomes in 1q, 2p, 7p, 9q, 18q, and Xq. Losses of 13q14.1-q14.2, 1p31, and 4q34-q35 indicated that Rb gene, ARHI, and FAT were deleted. Gains of 2p24.1, 1q23, and 7p12.3-p12.1 demonstrated that N-myc oncogene, FASL, GITRL, and EGFR were amplified. RT-PCR analysis showed that N-myc and EGFR were overexpressed, while Rb and ARHI were underexpressed.

CONCLUSIONS

This report is the first to show multiple chromosomal aberrations in PPENT arising from the ovary. The deletions of Rb, ARHI, and FAT, as well as amplification of N-myc, FASL, GITRL, and EGFR, may be the crucial factors for tumorigenesis and the aggressive biological behavior of PPNET.

Cytogenetic and histopathologic studies of congenital supratentorial primitive neuroectodermal tumors: a case report

Primitive neuroectodermal tumors (PNET) represent about 25% of primary central nervous system tumors in childhood, but congenital PNETs are rare. Cytogenetic studies and studies on molecular pathology have identified several genetic alterations in medulloblastoma, but molecular investigations on supratentorial PNETs are infrequent. We present a male newborn with a large congenital PNET of the right cerebral hemisphere and the molecular analysis of the tumor. Tumor tissue was investigated by routine histology and immunohistochemistry. Fluorescence in-situ hybridization was carried out on native tumor tissue to investigate deletions on chromosome 17p and to analyze c-Myc or N-Myc amplifications. Histologic examination revealed a primitive neuroectodermal tumor with massive extension covering almost the entire right hemisphere. Genetic analysis of the native tumor tissue of our patient excluded a deletion of chromosome 17p. An amplification of the c-Myc or N-Myc oncogene was absent using fluorescence in-situ hybridization. Despite unremarkable genetic analysis in our case prognosis was poor, suggesting that there are additional, yet unknown constitutional genetic aberrations in the pathogenesis of congenital supratentorial PNET.

Treatment strategies for medulloblastoma and primitive neuroectodermal tumors

Medulloblastoma and primitive neuroectodermal tumors (PNETs) are the most common malignant brain tumors in children. The concern for late sequelae of neuraxis irradiation and the obligation to improve disease-free survival in children who harbor malignant brain tumors has led to the additional provision of systemic chemotherapy to standard- and reduced-dose radiotherapy, as well as to the evaluation of alternate modes of radiotherapy delivery. Analysis of evidence has suggested that chemotherapy has an impact on length of survival in children with medulloblastoma and PNETs. The question remains as to whether chemotherapy combined with reduced-dose radiotherapy provides greater benefit than standard-dose radiotherapy alone, and which subset of children the treatment most benefits. Also unanswered is the question of whether chemotherapy can serve as the primary treatment in infants with these lesions. In an attempt to help answer these questions, the authors review the major chemotherapy and radiotherapy trials for newly diagnosed patients and those with recurrent medulloblastoma and PNETs.

Lipid association increases the potency against primary medulloblastoma cells and systemic exposure of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) in rats

PURPOSE

To reduce the systemic toxicity and prolong the systemic presence of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), a lipid-based drug carrier was designed and characterized.

METHODS

The degree of CCNU association with lipid vesicles composed of 1, 2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) (1:1, m/m) was characterized and the drug decomposition rates of lipid-drug complexes were monitored. Effects of lipid association on drug potency against medulloblastoma cells and total systemic drug exposure in rats were determined.

RESULTS

At a CCNU:lipid molar ratio greater than 1:5, more than 90% of the drug was associated with the lipid vesicles. In aqueous suspensions, lipid association significantly reduced the first-order drug decomposition rate. In addition, lipid-associated CCNU exhibited a 4-fold increase in drug sensitivity with medulloblastoma cells. IC50 values for CCNU admixed and encapsulated with lipid vesicles were 18+/-4.9 and 14.0+/-2.2 microM, respectively, compared to 83+/-11.0 microM for free CCNU. When administered to rats, lipid-associated CCNU increased the AUC (area under the concentration-time curve) of CCNU by approximately 2-fold (20.46+/-2.15 compared to 39.59+/-1.87 microg x min/ml), and the terminal half-life (t1/2beta) by almost 9-fold (17+/-9 compared to 147+/-48 min) over free CCNU. Despite the increase in total systemic drug exposure, rats treated with lipid-associated CCNU exhibited a significantly lower frequency of acute neurotoxicity.

CONCLUSIONS

These data indicate that CCNU associated with lipid vesicles may increase drug stability, potency, and systemic exposure in rats.

Synchronous radiochemotherapy in unfavorable brain tumors of children and young adults

The prognosis of patients with incompletely resected malignant brain tumors is almost fatal. In an attempt to improve the outcome of children and young adults with unfavorable brain tumors an intensive multimodal therapeutic strategy was developed combining simultaneous (hyper)fractionated external beam irradiation and conventional adjuvant chemotherapy after initial surgery. 17 patients aged between 2.10 and 25.11 years were entered into the study. 16/17 patients were treated according to the German/Austrian Pediatric Brain Tumor Study Group multicenter trial HIT '91. They are not protocol patients of this HIT '91 trial. Induction chemotherapy consisted of 2 courses of ifosfamide (3 g/m2/d) on days 1-3, etoposide (150 mg/m2/d) on days 4-6, methotrexate (5 g/m2) on days 15 and 22, cisplatin (40 mg/m2/d) and cytarabine (400 mg/m2/d) on days 29-31. Three weeks after the last dose of cisplatin/cytarabine the second course of chemotherapy was started. The last patient entered into the study received a modified therapy containing ifosfamide, cisplatin and etoposide. Synchronously at a median of 12 days after initiation of chemotherapy 12/17 patients received local radiotherapy (6000-7040 cGy) to the brain and 5/17 patients craniospinal irradiation (3520 cGy with a tumor boost of 1400-2000 cGy). 4-6 weeks after completion of the second course of chemotherapy maintenance therapy was started with carmustine (CCNU) (75 mg/m2) and carboplatin (400 mg/m2) each on day 1 and vincristine (1.5 mg/m2) on day 1, 8, 15. This course was repeated eight times every six weeks. 9/17 patients are alive at a median follow-up of 25 months (range 5-50) with 4 complete remissions, 2 partial remissions and 1 stable disease lasting 42+ months. Two patients, who initially had stable disease, progressed, but are still alive at 31+ and 41+ months after diagnosis. Median progression-free survival and median overall survival is 19 and 36 months, respectively. Hematologic and methotrexate-induced toxicity were severe and resulted in one therapy-related death. However, radiotherapy concomitant to chemotherapy appears to be an effective method of treatment for brain tumors with poor prognosis, though toxicity is severe in some cases.

CD95 ligand-induced apoptosis of human medulloblastoma cells

CD95 ligand (CD95L) is a cytotoxic cytokine that induces apoptosis in susceptible target cells. Medulloblastoma is the most common non-glial intrinsic malignancy of the brain. In this study, we have studied CD95-mediated apoptosis of human medulloblastoma cell lines. We found that DAOY, MED-1 and D-283 cells are susceptible to CD95L-induced apoptosis when RNA and protein synthesis are inhibited. Preexposure of D-283, but not DAOY or MED-1 cells, to interferon-gamma or tumor necrosis factor-alpha enhances CD95 expression and primes these cells for CD95-mediated apoptosis. Inhibitors of interleukin 1-converting enzyme (ICE)-like protease (caspase) activity block CD95L-induced cytotoxicity, suggesting that caspases mediate the death signal induced by CD95L in human medulloblastoma cells. Interestingly, medulloblastoma cells belong to an increasing number of tumor cell types that coexpress CD95 and CD95L. We conclude that CD95 may be a promising target of immunochemotherapy for human medulloblastoma.

Leptomeningeal metastases: rationale for systemic chemotherapy or what is the role of intra-CSF-chemotherapy?

Malignant subarachnoid deposits complicate both primary central nervous system (CNS) tumors and systemic neoplasms. Although the pathophysiology of symptoms and signs can not be separated by the category of primary tumors that seeds the leptomeninges, the approach to therapy is not similar in primary CNS tumors and in systemic neoplasms. Standard therapy for subarachnoid seeding in primary CNS tumors include conventional or high doses of systemic chemotherapy with various combinations of radiotherapy given either to limited fields or to the whole neuroaxis. Direct administration of chemotherapy to the CSF is not being used. In contrast, whenever a systemic tumor seeds the subarachnoid space the standard approach includes intensive intra-CSF chemotherapy, radiotherapy to limited or extended CNS fields and various combinations of systemic chemotherapy. The published experience with the conventional therapy is reviewed and is critically analyzed. Evidence indicating that high dose systemic chemotherapy can replace intra-CSF treatment in some subgroups are also reviewed and the rationale for this approach is specified. Recent experience in which intra-CSF therapy was prospectively eliminated from the treatment protocol of leptomeningeal metastases of solid tumors reveals that the response rate and survival are similar to those obtained by protocols that differed only by the inclusion of intra-CSF chemotherapy. Patients who were treated by radiotherapy alone combined with systemic chemotherapy but without the intra-CSF therapy were spared the high rate of early and delayed complications directly related to intra-CSF therapy. Still, treatment outcome did not differ. Therefore, future research efforts and prospective clinical trials should investigate the best chemotherapeutic schedules and their sequencing with radiotherapy or with more intensive complementary systemic chemotherapy schemes. Newly designed drugs with long circulation time and improved CNS penetration may serve for this purpose.