Proposed strategy for the use of high-dose chemotherapy with stem cell rescue and intrathecal topotecan without whole-brain irradiation for infantile classic medulloblastoma

Novel Strategy Involving High-Dose Chemotherapy with Stem Cell Rescue Followed by Intrathecal Topotecan Maintenance Therapy without Whole-Brain Irradiation for Atypical Teratoid/Rhabdoid Tumors

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare aggressive central nervous system tumor that typically affects children under three years old and has poor survival with a high risk for neurologic deficits. The primary purpose of this study was to successfully treat the disease and delay or avoid whole-brain radiotherapy for children with AT/RT. A retrospective analysis was performed for six children diagnosed with AT/RT and treated with multimodal treatment at a single institute between 2014 and 2020. Furthermore, germline SMARCB1 aberrations and MGMT methylation status of the tumors were analyzed. One patient who did not receive a modified IRS-III regimen replaced with ifosphamide, carboplatin, and etoposide (ICE) in induction chemotherapy was excluded from this analysis. Five patients who received ICE therapy were under three years old. After a surgical approach, they received intensive chemotherapy and high-dose chemotherapy with autologous peripheral blood stem cell transplantation (HDCT/autoPBSCT) followed by intrathecal topotecan maintenance therapy. Three patients underwent single HDCT/autoPBSCT, and the other two received sequential treatment. Two patients with germline SMARCB1 aberrations and metastases died of progressive AT/RT or therapy-related malignancy, while 3 with localized tumors without germline SMARCB1 aberrations remained alive. One survivor received local radiotherapy only, while the other two did not undergo radiotherapy. All three surviving patients were able to avoid whole-brain radiotherapy. Our results suggest that AT/RT patients with localized tumors without germline SMARCB1 aberrations can be rescued with multimodal therapy, including induction therapy containing ICE followed by HDCT/autoPBSCT and intrathecal topotecan maintenance therapy without radiotherapy. Further large-scale studies are necessary to confirm this hypothesis.

Preclinical validation of a novel therapeutic strategy for choroid plexus carcinoma

Choroid plexus carcinoma (CPC) is a rare infantile brain tumor with an aggressive clinical course that often leaves children with debilitating side effects due to aggressive and toxic chemotherapies. Development of novel therapeutical strategies for this disease have been extremely limited owing to the rarity of the disease and the paucity of biologically relevant substrates. We conducted the first high-throughput screen (HTS) on a human patient-derived CPC cell line (Children Cancer Hospital Egypt, CCHE-45) and identified 427 top hits highlighting key molecular targets in CPC. Furthermore, a combination screen with a wide variety of targets revealed multiple synergistic combinations that may pave the way for novel therapeutical strategies against CPC. Based on in vitro efficiency, central nervous system (CNS) penetrance ability and feasible translational potential, two combinations using a DNA alkylating or topoisomerase inhibitors in combination with an ataxia telangiectasia mutated and rad3 (ATR) inhibitor (topotecan/elimusertib and melphalan/elimusertib respectively) were validated in vitro and in vivo. Pharmacokinetic assays established increased brain penetrance with intra-arterial (IA) delivery over intra-venous (IV) delivery and demonstrated a higher CNS penetrance for the combination melphalan/elimusertib. The mechanisms of synergistic activity for melphalan/elimusertib were assessed through transcriptome analyses and showed dysregulation of key oncogenic pathways (e.g. MYC, mammalian target of rapamycin mTOR, p53) and activation of critical biological processes (e.g. DNA repair, apoptosis, hypoxia, interferon gamma). Importantly, IA administration of melphalan combined with elimusertib led to a significant increase in survival in a CPC genetic mouse model. In conclusion, this study is, to the best of our knowledge, the first that identifies multiple promising combinatorial therapeutics for CPC and emphasizes the potential of IA delivery for the treatment of CPC.

Development and Validation of an HPLC Method for Analysis of Topotecan in Human Cerebrospinal Fluid and Its Application in Elimination Evaluation of Topotecan after Intraventricular Injection

Intrathecal administration of anticancer drugs is an effective dosage strategy, but the elimination of intraventricular drugs is not uniform in all patients. For safety, a system to evaluate local pharmacokinetics in the ventricles after administration is desired. In this study, we developed a simple and reproducible method to measure topotecan concentration in the cerebrospinal fluid (CSF) and confirmed its clinical applicability. High-performance liquid chromatography (HPLC) analysis was performed using a C18 column to measure the total topotecan concentration in the CSF. Clinical CSF samples were obtained from a 1-year old child with poor CSF absorption and stagnation. The patient received topotecan via an intraventricular subcutaneous reservoir. The HPLC method complied with the validation criteria. The lower limit of quantitation of this method was 0.04 µM. Using the developed method, we could determine the difference in topotecan CSF concentrations at 24 and 48 h after administration. The patient's topotecan elimination rate was extremely low, and signs of adverse effects were observed at high CSF concentration of topotecan. The developed method could detect the delay in topotecan elimination after intrathecal injection. The findings of this study are valuable for the development of personalized treatments for the intrathecal administration of anticancer drugs.

Tandem High-dose Chemotherapy without Craniospinal Irradiation in Treatment of Non-metastatic Malignant Brain Tumors in Very Young Children

BACKGROUND

Infants and very young children with malignant brain tumors have a poorer survival and a higher risk for neurologic deficits. The present study evaluated the feasibility and effectiveness of multimodal treatment including tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT) in minimizing use of radiotherapy (RT) in very young children with non-metastatic malignant brain tumors.

METHODS

Twenty consecutive patients younger than 3 years were enrolled between 2004 and 2017. Tandem HDCT/auto-SCT was performed after six cycles of induction chemotherapy. Local RT was administered only to patients with post-operative gross residual tumor at older than 3 years. Since September 2015, early post-operative local RT for patients with atypical teratoid/rhabdoid tumor or primitive neuroectodermal tumor was administered.

RESULTS

All 20 enrolled patients underwent the first HDCT/auto-SCT, and 18 proceeded to the second. Two patients died from toxicity during the second HDCT/auto-SCT, and four patients experienced relapse/progression (one localized and three metastatic), three of whom remained alive after salvage treatment including RT. A total of 17 patients remained alive at a median 7.8 (range, 2.5-5.7) years from diagnosis. Nine survivors received no RT, six survivors received local RT alone, and two survivors who experienced metastatic relapse after tandem HDCT/auto-SCT received both local and craniospinal RT. The 5-year overall, event-free, and craniospinal RT-free survival rates were 85.0% ± 8.0%, 70.0% ± 10.2%, and 75.0% ± 9.7%, respectively. Neuroendocrine and neurocognitive functions evaluated 5 years after tandem HDCT/auto-SCT were acceptable.

CONCLUSION

Our results suggest that non-metastatic malignant brain tumors in very young children could be treated with multimodal therapy including tandem HDCT/auto-SCT while minimizing RT, particularly craniospinal RT.

Continuous and bolus intraventricular topotecan prolong survival in a mouse model of leptomeningeal medulloblastoma

Leptomeningeal metastasis remains a difficult clinical challenge. Some success has been achieved by direct administration of therapeutics into the cerebrospinal fluid (CSF) circumventing limitations imposed by the blood brain barrier. Here we investigated continuous infusion versus bolus injection of therapy into the CSF in a preclinical model of human Group 3 medulloblastoma, the molecular subgroup with the highest incidence of leptomeningeal disease. Initial tests of selected Group 3 human medulloblastoma cell lines in culture showed that D283 Med and D425 Med were resistant to cytosine arabinoside and methotrexate. D283 Med cells were also resistant to topotecan, whereas 1 μM topotecan killed over 99% of D425 Med cells. We therefore introduced D425 Med cells, modified to express firefly luciferase, into the CSF of immunodeficient mice. Mice were then treated with topotecan or saline in five groups: continuous intraventricular (IVT) topotecan via osmotic pump (5.28 μg/day), daily bolus IVT topotecan injections with a similar daily dose (6 μg/day), systemic intraperitoneal injections of a higher daily dose of topotecan (15 μg/day), daily IVT pumped saline and daily intraperitoneal injections of saline. Bioluminescence analyses revealed that both IVT topotecan treatments effectively slowed leptomeningeal tumor growth in the brains. Histological analysis showed that they were associated with localized brain necrosis, possibly due to backtracking of topotecan around the catheter. In the spines, bolus IVT topotecan showed a trend towards slower tumor growth compared to continuous (pump) IVT topotecan, as measured by bioluminescence. Both continuous and bolus topotecan IVT showed longer survival compared to other groups. Thus, both direct IVT topotecan CSF delivery methods produced better anti-medulloblastoma effect compared to systemic therapy at the dosages used here.

Medulloblastoma

Medulloblastoma accounts for nearly 10% of all childhood brain tumors. These tumors occur exclusively in the posterior fossa and have the potential for leptomeningeal spread. Treatment includes a combination of surgery, radiation therapy (in patients >3 years old). Patients >3 years old are stratified based on the volume of postoperative residual tumor and the presence or absence of metastases into "standard risk" and "high risk" categories with long-term survival rates of approximately 85% and 70%, respectively. Outcomes are inferior in infants and children younger than 3 years with exception of those patients with the medulloblastoma with extensive nodularity histologic subtype. Treatment for medulloblastoma is associated with significant morbidity, especially in the youngest patients. Recent molecular subclassification of medulloblastoma has potential prognostic and therapeutic implications. Future incorporation of molecular subgroups into treatment protocols will hopefully improve both survival outcomes and posttreatment quality of life.

IL-17 promoted the inhibition of medulloblastoma in mice by splenocyte injection

Background

Interleukin 17 (IL-17) is a proinflammatory cytokine produced by a new subset of activated CD4+ T cells, Th17 cells. We previously showed that increased Th17 cell populations were presented in human medulloblastoma-infiltrating T cells and peripheral blood. In this study, we attempted to address the possible role of Th17 cells in the biologic activity of IL-17 for tumor control.

Methods

We grafted fresh surgically obtained medulloblastoma into syngeneic athymic nude/nude mice. We intrapertonially injected splenocyte and murine IL-17 in mice on the second day. The tumor volume and the life spans of the mice were measured. Meanwhile, the IL-17, IL-6, IL-23, Ccl2, Ccl20 and IFN-gamma expression in the tumors was also examined by real-time PCR, Western blot and enzyme-linked immunosorbent assay.

Results

We found that medulloblastoma growth in IL-17-injected mice was significantly inhibited compared to the non-IL-17 treated mice. In contrast to the IL-17 antitumor activity observed in mice injected with splenocytes, we observed that IFN-gamma, IL-6, IL-23, Ccl2, and Ccl20 proteins were significantly increased in tumor tissues of mice injected with IL-17.

Conclusions

These experiments suggest that IL-17 may promote splenocyte antitumor activity in medulloblastoma. We postulate that IL-17’s antitumor activity may be related to the increased protein levels of IFN-gamma, IL-6, IL-23, Ccl2, and Ccl20.