Carboplatin in childhood medulloblastoma/PNET: feasibility of an in vivo sensitivity test in an "up-front" study

Questions and answers in the management of children with medulloblastoma over the time. How did we get here? A systematic review

Introduction

Treatment of children with medulloblastoma (MB) includes surgery, radiation therapy (RT) and chemotherapy (CT). Several treatment protocols and clinical trials have been developed over the time to maximize survival and minimize side effects.

Methods

We performed a systematic literature search in May 2023 using PubMed. We selected all clinical trials articles and multicenter studies focusing on MB. We excluded studies focusing exclusively on infants, adults, supratentorial PNETs or refractory/relapsed tumors, studies involving different tumors or different types of PNETs without differentiating survival, studies including <10 cases of MB, solely retrospective studies and those without reference to outcome and/or side effects after a defined treatment.

Results

1. The main poor-prognosis factors are: metastatic disease, anaplasia, MYC amplification, age younger than 36 months and some molecular subgroups. The postoperative residual tumor size is controversial.2. MB is a collection of diseases.3. MB is a curable disease at diagnosis, but survival is scarce upon relapse.4. Children should be treated by experienced neurosurgeons and in advanced centers.5. RT is an essential treatment for MB. It should be administered craniospinal, early and without interruptions.6. Craniospinal RT dose could be lowered in some low-risk patients, but these reductions should be done with caution to avoid relapses.7. Irradiation of the tumor area instead of the entire posterior fossa is safe enough.8. Hyperfractionated RT is not superior to conventional RT9. Both photon and proton RT are effective.10. CT increases survival, especially in high-risk patients.11. There are multiple drugs effective in MB. The combination of different drugs is appropriate management.12. CT should be administered after RT.13. The specific benefit of concomitant CT to RT is unknown.14. Intensified CT with stem cell rescue has no benefit compared to standard CT regimens.15. The efficacy of intraventricular/intrathecal CT is controversial.16. We should start to think about incorporating targeted therapies in front-line treatment.17. Survivors of MB still have significant side effects.

Conclusion

Survival rates of MB improved greatly from 1940-1970, but since then the improvement has been smaller. We should consider introducing targeted therapy as front-line therapy.

Safety and efficacy of concurrent carboplatin during full-dose craniospinal irradiation for high-risk/metastatic medulloblastoma in a resource-limited setting

PURPOSE

To assess the safety and efficacy of concurrent carboplatin during craniospinal irradiation (CSI) in high-risk/metastatic medulloblastoma defined as either residual tumor >1.5 cm² or leptomeningeal metastases.

METHODS

This single-arm combined prospective (2005-2011) and retrospective (2011-2019) study was undertaken at a tertiary care cancer center in India. Following surgery, patients with newly diagnosed high-risk/metastatic medulloblastoma received concurrent carboplatin (35 mg/m² ) for 15 days (day 1 to day 15) during CSI plus posterior fossa/tumor bed boost, followed by six cycles of standard adjuvant chemotherapy.

RESULTS

All 97 patients completed their planned course of radiotherapy without interruptions, except for two (2.1%) patients who had brief gaps due to treatment-related toxicity. Grade 3-4 anemia, neutropenia, thrombocytopenia, and febrile neutropenia were seen in four (4.1%), 41 (42.2%) 21 (21.6%), and 18 (18.6%) patients, necessitating packed cell transfusion, granulocyte colony-stimulating factor, and platelet support in five (5.1%), 41 (42.2%), and five (5.1%) patients, respectively, during the concurrent phase. Following myelorecovery, 92 (94.9%) patients completed the planned six cycles of standard adjuvant systemic chemotherapy. There were no treatment-related deaths during the concurrent chemo-radiotherapy phase, while three (3.1%) toxic deaths were ascribed to adjuvant chemotherapy-related complications. At a median follow-up of 82 months, the 5-year Kaplan-Meier estimates of progression-free survival and overall survival were 60.2% and 62.1%, respectively. On univariate analysis, leptomeningeal metastases (M0/M1 vs. M2/M3) and histological subtype (large cell/anaplastic vs. others) emerged as significant prognostic factors for survival.

CONCLUSION

Addition of concurrent carboplatin to RT as radiosensitizing chemotherapy is a simple and effective way of treatment intensification in high-risk/metastatic medulloblastoma.

Outcome and prognostic factors for children with supratentorial primitive neuroectodermal tumors treated with carboplatin during radiotherapy: a report from the Children's Oncology Group

BACKGROUND

Supratentorial PNETs (sPNET) are uncommon embryonal malignancies of the central nervous system whose prognosis has historically been poor. We evaluated the outcome and prognostic factors of children with sPNET treated prospectively on a Children's Oncology Group trial.

PROCEDURE

Following surgery, patients received craniospinal radiotherapy with concurrent carboplatin followed by six months of maintenance chemotherapy with cyclophosphamide and vincristine.

RESULTS

Five-year overall survival (OS) and progression-free survival (PFS) for all patients was 58 ± 7% and 48 ± 7%. For patients with pineoblastoma (n = 23), five-year OS and PFS was 81 ± 9% and 62 ± 11%. Extent of resection but not M-stage was prognostic. Five-year OS and PFS for 37 patients with non-pineal tumors (NPsPNET) was 44 ± 8% and 39 ± 8%, significantly worse than for PB (P = 0.055 and 0.009 respectively). Extent of resection and major radiotherapy deviations were prognostic. Five year OS was 59 +/- 11.4% for those undergoing complete resection versus 10.4 +/- 7% for those who did not (P = 0.017). Central pathologic review called 14 (38%) "classic" sPNET, 8 (22%) "undifferentiated" and 13 (35%) "malignant gliomas." There was no significant difference between the subgroups, although survival distributions approached significance when the combined "classic" and "undifferentiated" group was compared to the "malignant gliomas."

CONCLUSIONS

Carboplatin during RT followed by 6 months of non-intensive chemotherapy is a feasible treatment strategy for patients with sPNET. Aggressive surgical resection should be attempted if feasible. The classification of supratentorial small cell malignancies can be difficult.

Outcome of children with metastatic medulloblastoma treated with carboplatin during craniospinal radiotherapy: a Children's Oncology Group Phase I/II study

PURPOSE

We evaluated the feasibility of administering carboplatin as a radiosensitizer during craniospinal radiation therapy (CSRT) to patients with high-risk medulloblastomas (MBs) and supratentorial primitive neuroectodermal tumors, and we report the outcome in the subset with metastatic (M+) MB.

PATIENTS AND METHODS

After surgery, patients received 36 Gy CSRT with boosts to sites of disease. During radiation, patients received 15 to 30 doses of carboplatin (30-45 mg/m(2)/dose), along with vincristine (VCR) once per week for 6 weeks. Patients on regimen A received 6 months of maintenance chemotherapy (MC) with cyclophosphamide and VCR. Once the recommended phase II dose (RP2D) of carboplatin was determined, cisplatin was added to the MC (regimen B).

RESULTS

In all, 161 eligible patients (median age, 8.7 years; range, 3.1 to 21.6 years) were enrolled. Myelosuppression was dose limiting and 35 mg/m(2)/dose × 30 was determined to be the RP2D of carboplatin. Twenty-nine (36%) of 81 patients with M+ MB had diffuse anaplasia. Four patients were taken off study within 11 months of completing radiotherapy for presumed metastatic progression and are long-term survivors following palliative chemotherapy. Excluding these four patients, 5-year overall survival ± SE and progression-free survival ± SE for M+ patients treated at the RP2D on regimen A was 82% ± 9% and 71% ± 11% versus 68% ± 10% and 59% ± 10% on regimen B (P = .36). There was no difference in survival by M stage. Anaplasia was a negative predictor of outcome.

CONCLUSION

The use of carboplatin as a radiosensitizer is a promising strategy for patients with M+ MB. Early progression should be confirmed by biopsy.

Childhood medulloblastoma: current status of biology and treatment

Medulloblastoma, a primitive neuro-ectodermal tumour that arises in the posterior fossa, is the most common malignant brain tumour occurring in childhood. Over the past half century, the long-term survival for children with medulloblastoma has improved remarkably from a certain fatal diagnosis to a cancer that is often curable. Although overall survival for children with non-disseminated and non-anaplastic medulloblastoma can approach 80%, the current multidisciplinary therapeutic approach is not without long-term sequelae. Chemotherapy has improved the long-term survival and allowed for reductions in the amount of radiation given, thereby reducing some of the long-term toxicities. In this review, we describe the current understanding of the basic biology of medulloblastoma and report on the current active chemotherapeutic agents utilized in medulloblastoma therapy. Ultimately, our understanding of the basic biology of medulloblastoma may lead to further advances in therapy by providing targets that are more specific and potentially less toxic.

Pilot study of ifosfamide/carboplatin/etoposide (ICE) for peripheral blood stem cell mobilization in patients with high-risk or relapsed medulloblastoma

OBJECTIVES

The purpose of this study is to evaluate the stem cell mobilization capacity, anti-tumor effect, and feasibility of ifosfamide/carboplatin/etoposide (ICE) for transplant-eligible patients with medulloblastoma.

MATERIALS AND METHODS

Six patients (23 months to 18 years old) with high-risk or relapsed medulloblastoma received one cycle of ICE, which consisted of ifosfamide at 1.8 g/m(2) for 5 days, carboplatin 400 mg/m(2) for 2 days, and etoposide 100 mg/m(2) for 5 days. Stem cells were mobilized with ICE followed by granulocyte colony-stimulating factor at 10 microg kg(-1) day(-1).

RESULTS

After one cycle of ICE, the median number of harvested CD34+ cells per apheresis session was 11.85 x 10(6) cells/kg (range, 0.2 to 71.2 x 10(6) cells/kg). Two patients obtained a complete response and three patients a partial response. All patients experienced severe myelosuppression, and three infectious toxicities were observed.

CONCLUSIONS

These results suggest that ICE is optimal for mobilizing stem cells, effective for high-risk or relapsed medulloblastoma, and tolerable with limited non-hematological toxicity.

Results of a phase II upfront window of pharmacokinetically guided topotecan in high-risk medulloblastoma and supratentorial primitive neuroectodermal tumor

PURPOSE

To assess the antitumor efficacy of pharmacokinetically guided topotecan dosing in previously untreated patients with medulloblastoma and supratentorial primitive neuroectodermal tumors, and to evaluate plasma and CSF disposition of topotecan in these patients.

PATIENTS AND METHODS

After maximal surgical resection, 44 children with previously untreated high-risk medulloblastoma were enrolled, of which 36 were assessable for response. The topotecan window consisted of two cycles, administered initially as a 30-minute infusion daily for 5 days, lasting 6 weeks. Pharmacokinetic studies were conducted on day 1 to attain a topotecan lactone area under the plasma concentration-time curve (AUC) of 120 to 160 ng/mL.h. After 10 patients were enrolled, the infusion was modified to 4 hours, with dosage individualization.

RESULTS

Of 36 assessable patients, four patients (11.1%) had a complete response and six (16.6%) showed a partial response, and disease was stable in 17 patients (47.2%). Toxicity was mostly hematologic, with only one patient experiencing treatment delay. The target plasma AUC was achieved in 24 of 32 studies (75%) in the 30-minute infusion group, and in 58 of 93 studies (62%) in the 4-hour infusion group. The desired CSF topotecan exposure was achieved in seven of eight pharmacokinetic studies when the topotecan plasma AUC was within target range.

CONCLUSION

Topotecan is an effective agent against pediatric medulloblastoma in patients who have received no therapy other than surgery. Pharmacokinetically guided dosing achieved the target plasma AUC in the majority of patients. This drug warrants testing as part of standard postradiation chemotherapeutic regimens. Furthermore, these results emphasize the importance of translational research in drug development, which in this case identified an effective drug.

Clinical and cellular pharmacology in relation to solid tumours of childhood

Our understanding of the clinical and cellular pharmacology of drugs commonly used in the treatment of childhood cancer have increased greatly over the past two decades. However, with the exception of childhood acute lymphoblastic leukaemia (ALL), our current knowledge of factors such as inter-patient pharmacokinetic variability and cellular determinants of chemosensitivity has not been utilized in the design of integrated clinical studies. Recent pre-clinical and clinical evaluation of the topoisomerase I inhibitors topotecan and irinotecan has highlighted the potential importance of pharmacological factors in their effectiveness as cytotoxics. In this review, the clinical and cellular pharmacology of vincristine, actinomycin D, doxorubicin, cyclophosphamide, ifosfamide, cisplatin, carboplatin and etoposide will be discussed in relation to the major paediatric solid tumours. For each disease type, knowledge of the clinical and cellular pharmacology of a candidate drug will be related to pharmacodynamic responses such as response, toxicity and prognosis. For diseases such as Wilms' tumour, osteogenic sarcoma and Ewing's tumour, histological response to initial induction chemotherapy is of prognostic significance, and the depth of response is increasingly recognised as an important determinant of prognosis for high-risk neuroblastoma. For several of these tumour types, the dose-intensity of chemotherapy may be an important variable in determining prognosis. However the relationship between pharmacokinetic variability, cellular pharmacology and the major determinants of chemosensitivity to those drugs employed in first line therapy is unknown. The study of these relationships, by means of up front window studies in children who present with high-risk disease, may be as important as the introduction of new agents. Indeed, the optimisation of current therapies may be required to allow a fully informed selection of those children for whom novel therapies are truly needed. Funding and international collaboration at the clinical and scientific level would be required to achieve these aims.

What have we learnt from previous phase II trials to help in the management of childhood brain tumours?

Contrary to major advances in cure rates observed for almost all childhood cancers, progress in reducing brain tumour survival rates remains very limited. Although new drug development in oncology is founded on principles outlined in the organised methodology of phase I, II, and III trials, based on rigorous study design using standardised criteria, this approach has been applied very slowly in the field of neuro-oncology. There are multiple explanations for the paucity of well-conducted prospective clinical trials, such as the rarity and the heterogeneity of these tumours, and the reluctance of some investigators to enroll their patients in constraining trials. Data from the past two decades shows that several methodological problems preclude the drawing of any definite conclusions for the majority of drugs assessed. Among them, the necessity of a central neuropathological and neuroradiological review has been highlighted in, at least, two multicentric studies. Changes in histological diagnosis and grade have been reported in a proportion as high as 20%, and changes in response rate in 14% of the cases. This review of phase II trials for brain tumours reveals a wide array of sometimes arbitrary response definitions, that is if response is defined at all, and most series have enrolled small numbers of patients. We report on the different problems encountered in childhood brain tumours in these phase II trials, and their impact on phase III trials.

Treatment controversies in medulloblastoma

Medulloblastoma, the most common primary malignant brain tumor in children, is a radiosensitive and chemosensitive tumor. Nevertheless, medulloblastoma remains a management challenge for the clinical oncologist, because the optimal sequence and dosage for each treatment modality has not yet been defined. In addition, effective management strategies for medulloblastoma may result in profound neuroendocrine and neuropsychologic sequelae. In this article, we review the clinical and biologic prognostic factors for classifying medulloblastoma, current strategies for the management of this disease, and potential strategies to prevent or minimize long-term treatment sequelae.

Progressive disease in children with medulloblastoma/PNET during preradiation chemotherapy

The overall prognosis in children with medulloblastoma/PNET has not significantly improved over the past decade. Intensive neoadjuvant chemotherapy has not yet adequately explored. We evaluated the short-term clinical results of an intensive chemotherapy regimen in high risk children with newly diagnosed MB/PNET, after surgery and before radiation. Twelve previously untreated patients with high-risk medulloblastoma/PNET, according to Chang's classification, were treated with the following chemotherapy regimen: high dose carboplatin 600 mg/m2/day on days 1 and 2; the same course was administered 4 weeks later. One month later, high dose cyclophosphamide 2 g/m2/day on days 1 and 2, followed by an identical course 4 weeks later. Vincristine 1, 5 mg/m2 i.v. was given on the first day of each course. Systemic evaluation of the disease included imaging of the entire neuraxis, including MRI of the entire spine. Out of 12 enrolled, 7 patients were able to be evaluated for a residual disease after surgery. After two cycles of high dose carboplatin, we noted 1 CR, 4 PR and 2 MR. After the subsequent two cycles of high dose cyclophosphamide we observed an additional response in 4 cases. On the other hand, 4 patients clearly showed evidence of PD immediately after the first course of cyclophosphamide (2 cases) or following the second course. Three of the 4 patients had shown respectively 1 CR and 2 PR after the second course of carboplatin. Whereas it was confirmed that 2 courses of high dose carboplatin is effective in high risk MB/PNET children, we observed an unacceptable number of PD during the subsequent high dose cyclophosphamide therapy. A review from the literature also suggests that, in general, the longer radiotherapy is delayed, the higher the incidence of PD. In the search for the optimal drug combination in "sandwich chemotherapy" for children with high risk MB/PNET, PD must be reduced to an acceptable incidence, since a high number of PD may significantly lower the probability of long-term survival.

Childhood medulloblastoma: progress and future challenges

Medulloblastoma and other primitive neuroectodermal tumors are the most common malignant tumors of childhood. Progress has been slowly made in the management of such tumors. Long-term neurocognitive sequelae of treatment in children with medulloblastoma are common and recent treatment trials have attempted to reduce the amount of craniospinal radiation therapy or delay radiation therapy in attempts to reduce such sequelae. Surgery remains a critical component of treatment, although there is increasing concern about surgically-related complications, including the cerebellar mutism syndrome. For older children, craniospinal radiation remains an integral part of management. However, recent studies have suggested an excellent outcome after reduced-dose craniospinal radiation therapy and adjuvant chemotherapy. The role of chemotherapy is expanding for children with medulloblastoma and is now presently a component of protocols for children with average-risk and poor-risk disease. For children with poor-risk disease, intensifications of chemotherapy both during and after radiation therapy are presently being explored. Treatment of infants and young children with medulloblastoma remains problematic and a variety of different approaches are being investigated with the aims of both improving outcome and reducing long-term sequelae.

Etoposide-carboplatin association as 'emergency' up-front chemotherapy in a case of life-threatening adult medulloblastoma

Medulloblastoma is a rare tumor in the adult population. Current therapies include surgery and irradiation. Unlike in children, chemotherapy is not commonly used, and its potential has poorly been investigated to date. We report the case of an adult patient with disseminated medulloblastoma and fulminant neurological deterioration, precluding craniospinal irradiation. Emergency chemotherapy consisting of carboplatin (400 mg/m2) and etoposide (500 mg/m2) with intrathecal (i.t.) administration of cytosar and hydrocortisone was initiated. Impressive clinical response was achieved after the first cycle of chemotherapy, with the complete disappearance of the lesions detected by MRI. After 3 courses of chemotherapy, the patient underwent craniospinal irradiation (36 Gy to the entire neuraxis and 54 Gy to the posterior fossa). Two years after surgery, the patient was well, with complete clinical recovery, and a new MRI confirmed the disappearance of the lesions. Given the dramatic efficacy of the etoposide-carboplatin association (combined with i.t. cytosar), this regimen has to be considered in an emergency setting and seems to be a very attractive candidate to be investigated as first line therapy for poor risk medulloblastoma in adults.

Chemotherapy for medulloblastomas and primitive neuroectodermal tumors

In the past two decades, chemotherapy has proven to be an increasingly more effective modality in the treatment of medulloblastoma. Current evidence suggests that chemotherapy be included as part of standard treatment for all patients with high-risk medulloblastoma. Ongoing multi-centre trials are determining whether chemotherapy should be added to reduced dose radiotherapy as a substitute therapy for standard-dose radiotherapy. The major randomized and non-randomized chemotherapy trials for newly diagnosed patients with medulloblastoma or for patients at recurrence are presented. It is hoped that the addition of chemotherapy will eventually lead to improved survival rates as well as the reduction in the craniospinal radiotherapy dose for patients with medulloblastoma.

Preoperative chemotherapy with carboplatin alone in high risk medulloblastoma

Few studies have been carried out regarding preoperative chemotherapy utilized in the treatment of primitive neuroectodermal tumors/medulloblastomas (PNET/MB). In this paper, the authors report 3 cases of children under three years of age, with a presumed diagnosis of PNET/MB, who were preoperatively treated with chemotherapy consisting of high doses of carboplatin alone. The treatment improved the childrens' clinical condition prior to surgery and facilitated tumor removal, resulting in partial regression of the tumor. The preoperative single-drug therapy did not affect the histological diagnosis or prevent the presence of an effective degree of tumor sensitivity to the drug. All three children are still disease-free, after a mean follow-up period of 42 months.