Intrathecal Mafosfamide: A Preclinical Pharmacology and Phase I Trial

A Review on the Efficacy and Safety of Intrathecal Administration of Novel Medications for Leptomeningeal Metastases in Solid Cancers

Leptomeningeal disease (LMD) is a rare and lethal manifestation that may occur in the advanced stages of solid tumors and hematological malignancies. With advances in diagnostic techniques, the detection and confirmation of the presence of LMD have increased. Although its optimal treatment remains a challenge, the use of the intrathecal route for the delivery of novel therapeutics is now considered a promising drug delivery strategy to complement radiation and systemic-based therapies. Although methotrexate, cytarabine, and thiotepa have a long history in the treatment of LMD, other medications have also been shown to be beneficial. In this article, we have reviewed the effects of novel medications administered via the intrathecal route for the treatment of solid tumors. We have searched PubMed, Scopus, and Google Scholar databases till the end of September 2021 using the following keywords: "leptomeningeal disease", "leptomeningeal carcinomatosis", "leptomeningeal metastases", "solid tumors", "solid cancers", and "intrathecal". Our literature findings have uncovered that most studies on LMD, which occurs secondary to solid cancers, are available as 'case reports', and few clinical trials have been conducted to date. Single-drug (monotherapy) or combination drug therapy, administered via the intrathecal route, especially in metastatic breast and lung cancer, has been shown to improve patients' symptoms and overall lifespan, while exhibiting a low and acceptable prevalence of side effects. However, judgments/conclusions about the effectiveness and safety of these drugs still require further clinical evaluation.

Cerebrospinal fluid-administered therapies for leptomeningeal metastases from solid tumors

Aims/purpose: Leptomeningeal metastases (LM) are associated with substantial morbidity and mortality. Several approaches are used to treat LM, including intrathecally administered therapies. We consolidated current studies exploring intrathecal therapies for LM treatment. Patients & methods: A review of clinical trials using intrathecal agents was conducted with outcomes tabulated and trends described. 48 trials met the inclusion criteria. Initial investigations began with cytotoxic agents; following this were formulations with longer cerebrospinal fluid half-lives, targeted antibodies and radionucleotides. Results & conclusion: Outcomes were not reported consistently. Survival, when reported, remained poor. Intrathecal therapies for LM remain a viable option. Their use can be informed by an understanding of efficacy, safety and toxicity. They may be an important component of future LM treatments.

Vorinostat and isotretinoin with chemotherapy in young children with embryonal brain tumors: A report from the Pediatric Brain Tumor Consortium (PBTC-026)

BACKGROUND

Embryonal tumors of the CNS are the most common malignant tumors occurring in the first years of life. This study evaluated the feasibility and safety of incorporating novel non-cytotoxic therapy with vorinostat and isotretinoin to an intensive cytotoxic chemotherapy backbone.

METHODS

PBTC-026 was a prospective multi-institutional clinical trial for children <48 months of age with newly diagnosed embryonal tumors of the CNS. Treatment included three 21-day cycles of induction therapy with vorinostat and isotretinoin, cisplatin, vincristine, cyclophosphamide, and etoposide; three 28-day cycles of consolidation therapy with carboplatin and thiotepa followed by stem cell rescue; and twelve 28-day cycles of maintenance therapy with vorinostat and isotretinoin. Patients with M0 medulloblastoma (MB) received focal radiation following consolidation therapy. Molecular classification was by DNA methylation array.

RESULTS

Thirty-one patients with median age of 26 months (range 6-46) received treatment on study; 19 (61%) were male. Diagnosis was MB in 20 and supratentorial CNS embryonal tumor in 11. 24/31 patients completed induction therapy within a pre-specified feasibility window of 98 days. Five-year progression-free survival (PFS) and overall survival (OS) for all 31 patients were 55 ± 15 and 61 ± 13, respectively. Five-year PFS was 42 ± 13 for group 3 MB (n = 12); 80 ± 25 for SHH MB (n = 5); 33 ± 19 for embryonal tumor with multilayered rosettes (ETMR, n = 6).

CONCLUSION

It was safe and feasible to incorporate vorinostat and isotretinoin into an intensive chemotherapy regimen. Further study to define efficacy in this high-risk group of patients is warranted.

Use of Intraventricular Medications in Critically Ill Patients: A Systematic Review

New evidence and increased use of intracranial devices have increased the frequency of intraventricular (IVT) medication administration in the neurologic intensive care unit. Significant benefits and risks are associated with administration of medications directly into the central nervous system. This review summarizes important literature, along with key information for clinicians regarding the administration, dosing, monitoring, and adverse effects related to IVT medication usage. Multiple medications have supporting literature for their use in critically ill patients including amphotericin B, aminoglycosides, colistimethate, daptomycin, quinupristin/dalfopristin, vancomycin, alteplase, and nicardipine. Sterile preparation and delivery, along with different types of devices that support medication administration, are also reviewed. One randomized, placebo-controlled trial of alteplase demonstrated decreased mortality but no change in good functional outcome. Other reports of IVT medication use are mainly limited to case reports and retrospective case series. There is a need for increased research on the topic; however, several practical barriers decrease the likelihood of a large, placebo-controlled, prospective study for most indications. Providers should consider implementing protocols to maximize safety of IVT medication delivery to ensure optimal patient outcomes.

Leptomeningeal malignancy of childhood: sharing learning between childhood leukaemia and brain tumour trials

Leptomeningeal malignancy complicates childhood cancers, including leukaemias, brain tumours, and solid tumours. In leukaemia, such malignancy is thought to invade leptomeninges via the vascular route. In brain tumours, dissemination from the primary tumour, before or after surgery, via CSF pathways is assumed; however, evidence exists to support the vascular route of dissemination. Success in treating leptomeningeal malignancy represents a rate-limiting step to cure, which has been successfully overcome in leukaemia with intensified systemic therapy combined with intra-CSF therapy, which replaced cranial radiotherapy for many patients. This de-escalated CNS-directed therapy is still associated with some neurotoxicity. The balanced benefit justifies exploration of ways to further de-escalate CNS-directed therapy. For primary brain tumours, standard therapy is craniospinal radiotherapy, but attendant risk of acute and delayed brain injury and endocrine deficiencies compounds post-radiation impairment of spinal growth. Alternative ways of treating leptomeninges by intensifying drug therapy delivered to CSF are being investigated-preliminary evidence suggests improved outcomes. This Review seeks to describe methods of intra-CSF drug delivery and drugs in use, and consider how the technique could be modified and additional drugs might be selected for this route of administration.

A Pilot Phase 1 Study of Intrathecal Pemetrexed for Refractory Leptomeningeal Metastases From Non-small-cell Lung Cancer

Objectives: We aim to determine the feasibility, safety, maximally tolerated dose (MTD), recommended dose and potential anti-tumor activity of intrathecal pemetrexed (IP).

Materials and Methods: Lung adenocarcinoma patients with recurrent or progressive leptomeningeal metastases (LM) after intrathecal chemotherapy were recruited. IP dose was escalated from 10 mg. A minimum of three patients and a maximum of six were enrolled in each cohort. Schedule protocol was IP twice per week for 2 weeks in induction therapy, followed by once per week for 4 weeks in consolidation therapy. Serial samples of plasma and cerebrospinal fluid (CSF) were obtained for pharmacokinetic studies.

Results: Thirteen patients were enrolled between March 2017 and July 2018. EGFR driver oncogene was identified in most of the patients. Severe adverse events (AEs) were encountered in 31% (4/13) of the cases, including myelosuppression, radiculitis, and elevation of hepatic aminotransferases (EHA). Study protocol was revised due to lethal myelosuppression. Following protocol revision, vitamin B12 and folic acid supplementation was given at the beginning of treatment, and myelosuppression was well-controlled. Dose-limiting toxicities (DLT) were myelosuppression, radiculitis, and EHA. Two patients (2/2) developed dose-limiting myelosuppression at 15 mg level. One patient (1/6) experienced dose-limiting radiculitis and EHA at 10 mg level. MTD was 10 mg. Response rate was 31% (4/13) and disease control rate was 54% (7/13). The drug concentration showed a decreasing trend in serial CSF samples following each IP. After IP, the peak plasma concentration was reached at 4 h in two cases, 6 h in two cases, 9 h in one case, and 12 h in one case, respectively.

Conclusion: Pemetrexed was appropriate for intrathecal administration. IP at 10 mg dose in combination with vitamin supplementation on the schedule of 1–2 times per week showed controllable toxicity and good efficacy. This regimen paves the way for subsequent clinical trial.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT03101579.

Best practices for the use of intracerebroventricular drug delivery devices

For decades, intracerebroventricular (ICV), or intraventricular, devices have been used in the treatment of a broad range of pediatric and adult central nervous system (CNS) disorders. Due to the limited permeability of the blood brain barrier, diseases with CNS involvement may require direct administration of drugs into the brain to achieve full therapeutic effect. A recent comprehensive literature review on the clinical use and complications of ICV drug delivery revealed that device-associated complication rates are variable, and may be as high as 33% for non-infectious complications and 27% for infectious complications. The variability in reported safety outcomes may be driven by a lack of consensus on best practices of device use. Numerous studies have demonstrated that employing strict aseptic techniques and following stringent protocols can dramatically reduce complications. Key practices to be considered in facilitating the safe, long-term use of these devices are presented.

Evidence for intrathecal sodium butyrate as a novel option for leptomeningeal metastasis

INTRODUCTION

The prognosis for leptomeningeal metastasis (LM) remains extremely poor regardless of intrathecal chemotherapy with various drugs, and thus, new treatments are necessary. Butyrate is an endogenous 4-carbon saturated fatty acid, has been investigated as an anti-tumor agent because of its multiple suppressive effects on several tumors. In this study, we investigated the cellular basis of sodium butyrate (SB), a sodium salt compound of butyrate, in vitro and evaluated the clinical potential of intrathecal SB administration for LM in vivo.

METHODS

We examined SB's effects on Walker 256 rat mammary tumor cells with regard to cytotoxicity, cell morphology, colony formation, migration, and invasion. We also examined SB's neurotoxicity for primary neurons and primary astrocytes. We finally evaluated the potency of continuous intrathecal SB administration in rats with intrathecally transplanted breast tumors as an LM model.

RESULTS

Physiological SB concentrations (2-4 mM) induced growth suppression, morphological changes, and inhibition of migration and invasion, but did not exhibit neurotoxic effects on primary neurons and astrocytes. Continuous intrathecal SB administration in a rat LM model significantly increased survival periods with little neurotoxicity.

CONCLUSIONS

Continuous intrathecal SB administration significantly improved prognoses in a rat LM model, which suggests that SB is a promising therapy for LM.

Intracerebroventricular Delivery as a Safe, Long-Term Route of Drug Administration

Intrathecal delivery methods have been used for many decades to treat a broad range of central nervous system disorders. A literature review demonstrated that intracerebroventricular route is an established and well-tolerated method for prolonged central nervous system drug delivery in pediatric and adult populations. Intracerebroventricular devices were present in patients from one to 7156 days. The number of punctures per device ranged from 2 to 280. Noninfectious complication rates per patient (range, 1.0% to 33.0%) were similar to infectious complication rates (0.0% to 27.0%). Clinician experience and training and the use of strict aseptic techniques have been shown to reduce the frequency of complications.

Recent Advancements of Treatment for Leptomeningeal Carcinomatosis

Treatment of Leptomeningeal carcinomatosis (LMC) from solid cancers has not advanced noticeably since the introduction of intra-cerebrospinal fluid (CSF) chemotherapy in the 1970's. The marginal survival benefit and difficulty of intrathecal chemotherapy injection has hindered its wide spread use. Even after the introduction of intraventricular chemotherapy with Ommaya reservoir, frequent development of CSF flow disturbance, manifested as increased intracranial pressure (ICP), made injected drug to be distributed unevenly and thus, the therapy became ineffective. Systemic chemotherapy for LMC has been limited as effective CSF concentration can hardly be achieved except high dose methotrexate (MTX) intravenous administration. However, the introduction of small molecular weight target inhibitors for primary cancer treatment has changed the old concept of 'blood-brain barrier' as the ultimate barrier to systemically administered drugs. Conventional oral administration achieves an effective concentration at the nanomolar level. Furthermore, many studies report that a combined treatment of target inhibitor and intra-CSF chemotherapy significantly prolongs patient survival. Ventriculolumbar perfusion (VLP) chemotherapy has sought to increase drug delivery to the subarachnoid CSF space even in patients with disturbed CSF flow. Recently authors performed phase 1 and 2 clinical trial of VLP chemotherapy with MTX, and 3/4th of patients with increased ICP got controlled ICP and the survival was prolonged. Further trials are required with newly available drugs for CSF chemotherapy. Additionally, new LMC biologic/pharmacodynamic markers for early diagnosis and monitoring of the treatment response are to be identified with the help of advanced molecular biology techniques.

Development of selective inhibitors for human aldehyde dehydrogenase 3A1 (ALDH3A1) for the enhancement of cyclophosphamide cytotoxicity

Aldehyde dehydrogenase 3A1 (ALDH3A1) plays an important role in many cellular oxidative processes, including cancer chemoresistance, by metabolizing activated forms of oxazaphosphorine drugs such as cyclophosphamide (CP) and its analogues, such as mafosfamide (MF), ifosfamide (IFM), and 4-hydroperoxycyclophosphamide (4-HPCP). Compounds that can selectively target ALDH3A1 could permit delineation of its roles in these processes and could restore chemosensitivity in cancer cells that express this isoenzyme. Here we report the detailed kinetic and structural characterization of an ALDH3A1-selective inhibitor, CB29, previously identified in a high-throughput screen. Kinetic and crystallographic studies demonstrate that CB29 binds within the aldehyde substrate-binding site of ALDH3A1. Cellular proliferation of ALDH3A1-expressing lung adenocarcinoma (A549) and glioblastoma (SF767) cell lines, as well as ALDH3A1 non-expressing lung fibroblast (CCD-13Lu) cells, is unaffected by treatment with CB29 and its analogues alone. However, sensitivity toward the anti-proliferative effects of mafosfamide is enhanced by treatment with CB29 and its analogue in the tumor cells. In contrast, the sensitivity of CCD-13Lu cells toward mafosfamide was unaffected by the addition of these same compounds. CB29 is chemically distinct from the previously reported small-molecule inhibitors of ALDH isoenzymes and does not inhibit ALDH1A1, ALDH1A2, ALDH1A3, ALDH1B1, or ALDH2 isoenzymes at concentrations up to 250 μM. Thus, CB29 is a novel small molecule inhibitor of ALDH3A1, which might be useful as a chemical tool to delineate the role of ALDH3A1 in numerous metabolic pathways, including sensitizing ALDH3A1-positive cancer cells to oxazaphosphorines.

Leptomeningeal metastasis: a Response Assessment in Neuro-Oncology critical review of endpoints and response criteria of published randomized clinical trials

PURPOSE

To date, response criteria and optimal methods for assessment of outcome have not been standardized in patients with leptomeningeal metastasis (LM).

METHODS

A Response Assessment in Neuro-Oncology working group of experts in LM critically reviewed published literature regarding randomized clinical trials (RCTs) and trial design in patients with LM.

RESULTS

A literature review determined that 6 RCTs regarding the treatment of LM have been published, all of which assessed the response to intra-CSF based chemotherapy. Amongst these RCTs, only a single trial attempted to determine whether intra-CSF chemotherapy was of benefit compared with systemic therapy. Otherwise, this pragmatic question has not been formally addressed in patients with solid cancers and LM. The methodology of the 6 RCTs varied widely with respect to pretreatment evaluation, type of treatment, and response to treatment. Additionally there was little uniformity in reporting of treatment-related toxicity. One RCT suggests no advantage of combined versus single-agent intra-CSF chemotherapy in patients with LM. No specific intra-CSF regimen has shown superior efficacy in the treatment of LM, with the exception of liposomal cytarabine in patients with lymphomatous meningitis. Problematic with all RCTs is the lack of standardization with respect to response criteria. There was considerable variation in definitions of response by clinical examination, neuroimaging, and CSF analysis.

CONCLUSION

Based upon a review of published RCTs in LM, there exists a significant unmet need for guidelines for evaluating patients with LM in clinical practice as well as for response assessment in clinical trials.

Selective ALDH3A1 inhibition by benzimidazole analogues increase mafosfamide sensitivity in cancer cells

Aldehyde dehydrogenase enzymes irreversibly oxidize aldehydes generated from metabolism of amino acids, fatty acids, food, smoke, additives, and xenobiotic drugs. Cyclophosphamide is one such xenobiotic used in cancer therapies. Upon activation, cyclophosphamide forms an intermediate, aldophosphamide, which can be detoxified to carboxyphosphamide by aldehyde dehydrogenases (ALDH), especially ALDH1A1 and ALDH3A1. Consequently, selective inhibition of ALDH3A1 could increase chemosensitivity toward cyclophosphamide in ALDH3A1 expressing tumors. Here, we report detailed kinetics and structural characterization of a highly selective submicromolar inhibitor of ALDH3A1, 1-[(4-fluorophenyl)sulfonyl]-2-methyl-1H-benzimidazole (CB7, IC50 of 0.2 μM). CB7 does not inhibit ALDH1A1, ALDH1A2, ALDH1A3, ALDH1B1, or ALDH2 activity. Structural, kinetics, and mutagenesis studies show that CB7 binds to the aldehyde binding pocket of ALDH3A1. ALDH3A1-expressing lung adenocarcinoma and glioblastoma cell lines are sensitized toward mafosfamide (MF) treatment in the presence analogues of CB7, whereas primary lung fibroblasts lacking ALDH3A1 expression, are not.

Treatment of leptomeningeal spread of NSCLC: a continuing challenge

OPINION STATEMENT

Leptomeningeal metastasis is a serious and frequently fatal complication of non-small cell lung cancer. Curative treatment remains elusive, but careful use of radiation, systemic chemotherapy, intrathecal chemotherapy, and symptoms management can greatly improve quality of life and survival. For most patients, we recommend a combination of skull-based radiation with focal radiation to any symptomatic spinal segments followed by systemic chemotherapy. For patients with EGFR mutations, erlotinib may be used as first-line therapy in a daily or high-dose regimen. Pemetrexed has promise for use in patients with brain and leptomeningeal metastases. Patients with multiple comorbidities or low performance status may tolerate intrathecal therapy better than systemic chemotherapy. The most commonly used intrathecal chemotherapies are methotrexate and liposomal cytarabine, although newer agents, such as topotecan and mafosfamide, may be more effective. Elevated intracranial pressure, which causes headaches, vertigo, nausea, and vomiting, should be treated with dexamethasone and acetazolamide. In select patients, cerebrospinal fluid shunting may be considered. The use of antidepressants, central nervous system stimulants, benzodiazepines, antiemetics, and pain medications can increase quality of life in patients with leptomeningeal metastases.

Challenges in drug delivery to tumors of the central nervous system: an overview of pharmacological and surgical considerations

The majority of newly diagnosed brain tumors are treated with surgery, radiation, and the chemotherapeutic temozolomide. Development of additional therapeutics to improve treatment outcomes is complicated by the blood-brain barrier (BBB), which acts to protect healthy tissue from chemical insults. The high pressure found within brain tumors adds a challenge to local delivery of therapy by limiting the distribution of bolus injections. Here we discuss various drug delivery strategies, including convection-enhanced delivery, intranasal delivery, and intrathecal delivery, as well as pharmacological strategies for improving therapeutic efficacy, such as blood-brain barrier disruption.

Oxazaphosphorine bioactivation and detoxification The role of xenobiotic receptors

Oxazaphosphorines, with the most representative members including cyclophosphamide, ifosfamide, and trofosfamide, constitute a class of alkylating agents that have a broad spectrum of anticancer activity against many malignant ailments including both solid tumors such as breast cancer and hematological malignancies such as leukemia and lymphoma. Most oxazaphosphorines are prodrugs that require hepatic cytochrome P450 enzymes to generate active alkylating moieties before manifesting their chemotherapeutic effects. Meanwhile, oxazaphosphorines can also be transformed into non-therapeutic byproducts by various drug-metabolizing enzymes. Clinically, oxazaphosphorines are often administered in combination with other chemotherapeutics in adjuvant treatments. As such, the therapeutic efficacy, off-target toxicity, and unintentional drug-drug interactions of oxazaphosphorines have been long-lasting clinical concerns and heightened focuses of scientific literatures. Recent evidence suggests that xenobiotic receptors may play important roles in regulating the metabolism and clearance of oxazaphosphorines. Drugs as modulators of xenobiotic receptors can affect the therapeutic efficacy, cytotoxicity, and pharmacokinetics of coadministered oxazaphosphorines, providing a new molecular mechanism of drug-drug interactions. Here, we review current advances regarding the influence of xenobiotic receptors, particularly, the constitutive androstane receptor, the pregnane X receptor and the aryl hydrocarbon receptor, on the bioactivation and detoxification of oxazaphosphorines, with a focus on cyclophosphamide and ifosfamide.

Leptomeningeal disease

Leptomeningeal metastasis (LMD) is a lethal complication caused by a variety of cancers, typically developing late in the disease course. It is associated with major neurologic disabilities and short survival. The incidence of LMD may increase because of longer survival of patients who have cancer, and because of the use of newer large-molecule therapies with poor central nervous system penetration. To achieve improved outcomes for patients who have LMD, new treatments need to reach the meninges and cerebrospinal fluid and interact with relevant molecular targets. Some of the agents currently in testing may contribute to this goal. To allow for better outcomes through earlier treatment, advances in diagnosis are needed. By using agents with higher therapeutic indices, in patients with a lower burden of disease (identified earlier with clinical or molecular markers) it should be possible to achieve gradual improvements in outcomes for patients suffering from this devastating disease.

Liposomal cytarabine for central nervous system embryonal tumors in children and young adults

To assess the tolerability and efficacy of liposomal cytarabine (LC), an encapsulated, sustained-release, intrathecal (IT) formulation of cytosine arabinoside, in de novo and relapsed central nervous system (CNS) embryonal tumors in children and young adults. We studied retrospectively all patients less than age 30 at our institution treated consecutively with LC for medulloblastoma (MB), primitive neuroectodermal tumor (PNET), and atypical teratoid rhabdoid tumor (ATRT). Seventeen patients received LC (2 mg/kg up to 50 mg, every 2 weeks to monthly) at diagnosis of high-risk CNS embryonal tumor (2 PNET, 3 ATRT) or relapse of MB (12 MB; 9 had leptomeningeal metastases). Sixteen patients received concurrent systemic chemotherapy. A total of 108 doses were administered (IT 82, intraventricular 26) with a mean of six (range 1-16) treatments per patient. Only three administrations were associated with adverse effects of arachnoiditis or headache. None developed malignant cerebrospinal fluid (CSF) cytology while receiving LC. All the six evaluable patients with malignant CSF cytology and treated with at least two doses cleared their CSF (mean 3 doses, range 1-5). Median overall survival in relapse patients was 9.1 months. Five patients (4 de novo and 1 relapsed) remain alive in complete remission for a median 26.8 months from first LC. Liposomal cytarabine is an easily administered, well-tolerated, and active drug in patients with high-risk embryonal neoplasms. One-third of our cohort remains in remission from otherwise fatal diagnoses. Our findings warrant a phase II trial of LC in newly diagnosed or recurrent CNS embryonal tumors.

Intrathecal chemotherapy for treatment of leptomeningeal dissemination of metastatic tumours

Neoplastic meningitis consists of diffuse involvement of the leptomeninges by infiltrating cancer cells, and can be caused by systemic or primary CNS tumours, such as solid cancers or lymphoproliferative malignant disease. Neoplastic meningitis is characterised by multifocal neurological signs and symptoms. Thus, careful neurological examination is needed for diagnosis of secondary diffuse involvement. Survival of patients with neoplastic meningitis is short (3-4 months), although some patients have long-lasting remission. Because most patients with neoplastic meningitis have diffuse systemic disease, treatment is typically palliative. However, more aggressive treatments are available to low-risk patients, which could increase survival. Therefore, identification of low-risk patients is important. Intrathecal chemotherapy is currently the main treatment for patients with neoplastic meningitis, but optimum anticancer chemotherapy is being studied.

Safety and toxicity of intrathecal liposomal cytarabine (Depocyte) in children and adolescents with recurrent or refractory brain tumors: a multi-institutional retrospective study

This retrospective study aimed to evaluate the safety and toxicity of intrathecal liposomal cytarabine (Depocyte) in children and adolescents with refractory or recurrent brain tumors. Nineteen heavily pretreated patients (males, n = 14; females, n = 5; median age at diagnosis 8.5 years; range, 1.4-22 years) were given intrathecal liposomal cytarabine on a compassionate use basis for recurrent refractory medulloblastoma (n = 12), mixed germ cell tumor (n = 2), central nervous system primitive neuroectodermal tumors of the pons (n = 1), anaplastic ependymoma (n = 1), anaplastic oligodendroglioma (n = 1), atypical teratoid rhabdoid tumor (n = 1), or rhabdoid papillary meningioma (n = 1). Eighteen patients received concomitant systemic radiochemotherapy. A total of 88 intrathecal injections of liposomal cytarabine (dose range, 20-50 mg) were administered with concomitant dexamethasone prophylaxis. The median number of doses per patient was four (range, 1-10). Duration of treatment ranged from (1/2) to 10 months. Eleven patients (57.9%) did not show any side effects, whereas eight patients (42.1%) developed side effects related to either chemical arachnoiditis (n = 4) or neurological progression (n = 2). Less typical treatment-related symptoms (e.g. lethargy, ataxia, and slurred speech) were observed in two patients. Treatment with intrathecal liposomal cytarabine was discontinued twice because of side effects. In conclusion, although intrathecal liposomal cytarabine was generally well tolerated, it should be used cautiously and only with dexamethasone prophylaxis in extensively pretreated patients with recurrent brain tumors. Proof of efficacy requires a prospective single-agent phase II study.

Need for a new treatment strategy: leptomeningeal carcinomatosis from gastric cancer

Leptomeningeal carcinomatosis (LMC) is an extremely rare manifestation of gastric cancer. The treatment options are very limited for LMC; despite standard treatment with intrathecal chemotherapy, the prognosis is grim and the median overall survival is 3-4 months. Here we report on a patient with LMC from metastatic gastric cancer who was treated with a novel approach of high-dose systemic irinotecan, comparable with the dose utilized in treating primary brain tumors such as gliomas. Our patient not only had an excellent tumor response to this novel approach, but also had a prolonged overall survival of 13 months, which is unusual for LMC from gastric cancer.

Leptomeningeal neoplasms

Leptomeningeal metastasis is becoming an increasingly important late complication of cancer as survival from systemic disease increases, and due to the fact that many novel cancer drugs fail to achieve therapeutic concentrations in the central nervous system. It occurs when neoplastic cells enter cerebrospinal fluid (CSF) pathways, causing diffuse infiltration of the subarachnoid space of the brain and spinal cord. Definitive diagnosis is established by the demonstration of malignant cells in the CSF. However, in certain circumstances the presence of leptomeningeal enhancement on brain or spinal MRI may be sufficient to make the diagnosis. Early diagnosis and aggressive treatment may delay neurologic progression and can lead to prolonged survival and improvement of neurologic function in certain patients. The prognosis depends on the underlying malignancy but is often poor, with a median survival of 4 months, and most treatment interventions are palliative. Nevertheless, some patients respond to treatment, and some survive beyond 1 or 2 years after diagnosis. Areas of radiographic bulky disease or symptomatic tumor should receive radiotherapy. Intrathecal chemotherapy is most effective in patients with lymphoma, leukemia, or breast cancer and without evidence of bulky disease on neuroimaging. Intrathecal chemotherapy requires normal CSF flow, and the most commonly used agents are methotrexate, cytarabine, and thiotepa. In lieu of intrathecal therapy, systemic chemotherapy may occasionally be indicated in select patients in part based on its ability to penetrate into bulky disease. When hydrocephalus occurs, ventriculoperitoneal shunting frequently leads to rapid clinical improvement. There is hope that progress in diagnostic modalities and the development of more effective intrathecal antineoplastic drugs may decrease neurologic morbidity and improve quality of life and survival.

Synergy of karenitecin and mafosfamide in pediatric leukemia, medulloblastoma, and neuroblastoma cell lines

BACKGROUND

A major barrier to treatment of leptomeningeal disease is the lack of proven combination chemotherapy regimens for intrathecal administration. The purpose of this study was to determine the cytotoxic effects of karenitecin and mafosfamide in vitro against leukemia, medulloblastoma, and neuroblastoma cell lines.

PROCEDURE

A modified methyl tetrazolium (MTT) assay was used to determine the sensitivity of the cells to karenitecin and mafosfamide. Cells were exposed to drug for 72 hr, after which the number of surviving cells was quantitated. For drug combination experiments, cells were exposed to medium alone (controls), single drugs alone (mafosfamide only, karenitecin only) or to different concentrations of the combination of the two drugs (karenitecin + mafosfamide), for a total of 36 concentration pairs per plate. The universal response surface approach (URSA) was used to analyze the cytotoxic effects of the combination of karenitecin and mafosfamide.

RESULTS

The IC(50)s of karenitecin and mafosfamide for the various cell lines were similar. For both drugs nearly complete inhibition of cell growth was demonstrated at higher concentrations in all cell lines. In the neuroblastoma cell lines (SK-N-DZ; SK-N-SH) and the DAOY medulloblastoma cell line, the combination of karenitecin and mafosfamide were synergistic. In the D283 medulloblastoma and both the leukemia cell lines (JM1 and Molt-4), the drug interaction was additive. Antagonism was not seen in any cell line.

CONCLUSIONS

Karenitecin and mafosfamide are additive or synergistic in vitro against tumor types that disseminate to the leptomeninges. These results provide guidance for the choice of potential combination intrathecal regimens.

Treatment of central nervous system metastases: parenchymal, epidural, and leptomeningeal

PURPOSE OF REVIEW

With prolonged survival from systemic therapies in the adjuvant and salvage setting, and because these agents cannot cross the intact blood-brain barrier, central nervous system metastases are becoming a therapeutic challenge in oncology.

RECENT FINDINGS

Recent therapeutic achievements include an extended use of surgery and radiosurgery. Although each of these treatment modalities has its own indications, in patients eligible for both treatments the upfront comparison of these two techniques has not been performed yet. Systemic chemotherapies and biotherapies may be effective in the management of central nervous system metastases as they may act on both neurologic and extra-central nervous system lesions. In the treatment of epidural metastases, a surgical procedure providing immediate direct circumferential decompression of the spinal cord followed by local irradiation has been demonstrated in a prospective randomized trial. The management of leptomeningeal metastases remains controversial and of limited efficacy especially in chemoresistant tumours and still relies on the combination of chemotherapy (intrathecal and intravenous) and focal radiotherapy.

SUMMARY

Aggressive treatments in patients with early diagnosis and in whom central nervous system metastases are the life-threatening location may provide a substantial increase in survival and favourably affect quality of life.

Feasibility and toxicity of intrathecal liposomal cytarabine in 5 children and young adults with refractory neoplastic meningitis

Intrathecal (IT) treatment of neoplastic meningitis secondary to relapsed or refractory malignancies is a major challenge for clinicians. We studied feasibility and toxicity of IT administered liposomal cytarabine on a compassionate basis in 5 patients (male, n=4; female, n=1; age at diagnosis 5 to 18 y) with recurrent acute lymphoblastic leukemia (n=3), primary refractory acute myeloid leukemia (n=1), or relapsed medulloblastoma (n=1). All of them had evidence of meningeal involvement as shown by presence of leukemic blasts or solid tumor cells on cytologic examination of cerebrospinal fluid and were refractory to standard central nervous system (CNS) therapy. A total of 33 doses were given. Leukemic blasts or solid tumor cells were cleared from cerebrospinal fluid in all patients. IT liposomal cytarabine was well tolerated in 2 patients, but may have contributed to neurologic side effects in 2 other patients with 1 patient who received high-dose methotrexate 96 hours before IT liposomal cytarabine developing transient encephalopathy. Another patient experienced seizures after 6 well-tolerated doses of IT liposomal cytarabine. In the fifth patient, treatment with IT liposomal cytarabine was not continued after a single dose because of toxic cauda equina syndrome, resulting from previous intensive CNS therapy. If administered simultaneously to other neurotoxic drugs, IT liposomal cytarabine may contribute to neurologic side effects in patients who had received prior intensive CNS-directed therapy. IT liposomal cytarabine should, therefore, be used cautiously, if a patient receives other potentially neurotoxic drugs simultaneously.

Chemotherapy in neoplastic meningitis

Neoplastic meningitis (NM) is the result of the diffuse or multifocal localization of cancer cells in the cerebral spinal fluid (CSF). NM is more often a late complication of solid tumor or lymphoproliferative malignancies. At present, the goal of therapeutic strategies is palliative and the evaluation of high or low risk is important in identifying which patients could benefit from aggressive treatments such as radiation therapy and chemotherapy. Given that NM is a cancer complication that can spread throughout the entire subarachnoid space, chemotherapy, whether intrathecal or systemic, is currently considered the best treatment option, but optimal treatment is still controversial. This review summarizes intrathecal and systemic chemotherapeutic options in the treatment of NM and the related toxicities.

New agents for intrathecal administration

Intrathecal administration of chemotherapy, with or without radiation therapy, is the primary treatment modality for the prevention and treatment of central nervous system (CNS) metastases in patients with leukemia or lymphoma. Although this treatment strategy has been very effective for patients with hematological malignancies, currently available intrathecal agents are relatively ineffective for patients with neoplastic meningitis resulting from an underlying solid or CNS tumor effective. This article provides an overview of some of the practical considerations and limitations associated with intrathecal chemotherapy, and is followed by a comprehensive review of some of the preclinical and early phase clinical trials of novel anticancer agents and treatment strategies using the intrathecal route.

Current treatment approaches to early childhood medulloblastoma

Treatment of medulloblastoma, the most common malignant brain tumor of childhood, is particularly challenging in very young children, owing to the increased susceptibility of the immature brain to treatment-induced neurocognitive deficits. Three promising strategies have been developed in combination with systemic postoperative chemotherapy, to avoid craniospinal irradiation for young children with nonmetastatic medulloblastoma, these include: high-dose chemotherapy, with and without local radiotherapy; intraventricular chemotherapy; and local radiotherapy. More intensified strategies may be required for metastatic medulloblastoma. Future studies will clarify the prognostic relevance of desmoplasia, postoperative residual tumor and biological markers to improve stratification criteria by risk-adapted treatment recommendations. An international Phase III trial for young children with nonmetastatic medulloblastoma, comparing survival rates and neurocognitive outcomes of different treatment strategies by standardized criteria, is under discussion.

Neoplastic meningitis from systemic malignancies: diagnosis, prognosis and treatment

Long-term survival is occasionally observed in patients with neoplastic meningitis (NM) accompanying breast cancer (13% one-year and 6% 2-year survival), melanoma, and lymphoma, but in general the survival of most patients is short and averages only 3 to 4 months. The incidence of NM appears to be increasing, in part due to earlier detection by magnetic resonance imaging (MRI), and in part due to development of more effective therapies for systemic cancer, which has resulted in a larger subset at risk for late-stage development of this complication. Survival of NM patients is negatively affected by concomitant progression of systemic disease despite multiple prior therapies. However, there are certain prognostic factors that have been identified as "favorable" in retrospective series, including age less than 60 years, long symptom duration, controlled systemic disease, Karnofsky performance status (KPS) > or =70, lack of encephalopathy or cranial nerve deficits, low initial cerebrospinal fluid (CSF) protein level, history of breast primary tumor, and lack of evidence of CSF compartmentalization or bulky meningeal disease as determined by CSF flow studies. Standard treatment has traditionally involved radiotherapy (RT) to sites of symptomatic or bulky disease, as detected by neuroimaging, and in selected patients, the administration of intrathecal, intraventricular, or systemic chemotherapy. However, treatment remains palliative and many patients and physicians choose supportive care only. Future hope is provided by studies that have improved our understanding of the disease pathogenesis, have identified prognostic variables associated with outcome, and have provided new therapeutic approaches, such as administration of high-dose systemic chemotherapy and investigations of novel therapeutic agents.

Neoplastic meningitis

Neoplastic meningitis is a complication of the CNS that occurs in 3-5% of patients with cancer and is characterised by multifocal neurological signs and symptoms. Diagnosis is problematic because the disease is commonly the result of pleomorphic manifestations of neoplastic meningitis and co-occurrence of disease at other sites. Useful tests to establish diagnosis and guide treatment include MRI of the brain and spine, cerebrospinal fluid (CSF) cytology, and radioisotope CSF flow studies. Assessment of the extent of disease of the CNS is of value because large-volume subarachnoid disease or CSF flow obstruction is prognostically significant. Radiotherapy is an established and beneficial treatment for patients with neoplastic meningitis with large tumour volume including parenchymal brain metastasis, sites of symptomatic disease, or CSF flow block. Because neoplastic meningitis affects the entire neuraxis, chemotherapy treatment can include intra-CSF fluid (either intraventricular or intralumbar) or systemic therapy. Most patients (>70%) with neoplastic meningitis have progressive systemic disease and consequently treatment is palliative and tumour response is of restricted durability. Furthermore, as there is no compelling evidence of a survival advantage with aggressive multimodal treatment, future trials need be done to determine the effect of treatment on quality of life and control of neurological symptoms.

Topotecan, thiotepa, and carboplatin for neuroblastoma: failure to prevent relapse in the central nervous system

We report on a three-drug myeloablative regimen designed to consolidate remission and to prevent central nervous system (CNS) relapse of high-risk neuroblastoma (NB). Sixty-six NB patients received topotecan 2 mg/m2/day, x 4 days; thiotepa 300 mg/m2/day, x 3 days; and carboplatin approximately 500 mg/m2/day, x 3 days. Post-SCT treatments included radiotherapy, immunotherapy, 13-cis-retinoic acid, +/-oral etoposide. Significant nonhematologic toxicities were mucositis and skin-related in all patients, convulsions in three patients, and cardiac failure and venocclusive disease of liver in one patient each. Grade 2 hepatotoxicity led to truncating cytoreduction in two patients; both later relapsed in brain. Among 46 patients transplanted in first complete/very good partial remission (CR/VGPR), event-free survival is 54% (s.e.+/-8%) at 36 months post-SCT; notable events were three non-NB-related deaths (adenovirus on day +9, bowel necrosis at 5 months, multiorgan failure at seven months) and four relapses in brain. Of 12 patients transplanted with evidence of NB, two became long-term event-free survivors and two relapsed in the brain. Of eight patients transplanted in second or greater CR/VGPR, one became a long-term event-free survivor and seven relapsed though not in the CNS. This regimen has manageable toxicity but does not prevent CNS relapse.

Metabolism and transport of oxazaphosphorines and the clinical implications

The oxazaphosphorines including cyclophosphamide (CPA), ifosfamide (IFO), and trofosfamide represent an important group of therapeutic agents due to their substantial antitumor and immuno-modulating activity. CPA is widely used as an anticancer drug, an immunosuppressant, and for the mobilization of hematopoetic progenitor cells from the bone marrow into peripheral blood prior to bone marrow transplantation for aplastic anemia, leukemia, and other malignancies. New oxazaphosphorines derivatives have been developed in an attempt to improve selectivity and response with reduced toxicity. These derivatives include mafosfamide (NSC 345842), glufosfamide (D19575, beta-D-glucosylisophosphoramide mustard), NSC 612567 (aldophosphamide perhydrothiazine), and NSC 613060 (aldophosphamide thiazolidine). This review highlights the metabolism and transport of these oxazaphosphorines (mainly CPA and IFO, as these two oxazaphosphorine drugs are the most widely used alkylating agents) and the clinical implications. Both CPA and IFO are prodrugs that require activation by hepatic cytochrome P450 (CYP)-catalyzed 4-hydroxylation, yielding cytotoxic nitrogen mustards capable of reacting with DNA molecules to form crosslinks and lead to cell apoptosis and/or necrosis. Such prodrug activation can be enhanced within tumor cells by the CYP-based gene directed-enzyme prodrug therapy (GDEPT) approach. However, those newly synthesized oxazaphosphorine derivatives such as glufosfamide, NSC 612567 and NSC 613060, do not need hepatic activation. They are activated through other enzymatic and/or non-enzymatic pathways. For example, both NSC 612567 and NSC 613060 can be activated by plain phosphodiesterase (PDEs) in plasma and other tissues or by the high-affinity nuclear 3'-5' exonucleases associated with DNA polymerases, such as DNA polymerases and epsilon. The alternative CYP-catalyzed inactivation pathway by N-dechloroethylation generates the neurotoxic and nephrotoxic byproduct chloroacetaldehyde (CAA). Various aldehyde dehydrogenases (ALDHs) and glutathione S-transferases (GSTs) are involved in the detoxification of oxazaphosphorine metabolites. The metabolism of oxazaphosphorines is auto-inducible, with the activation of the orphan nuclear receptor pregnane X receptor (PXR) being the major mechanism. Oxazaphosphorine metabolism is affected by a number of factors associated with the drugs (e.g., dosage, route of administration, chirality, and drug combination) and patients (e.g., age, gender, renal and hepatic function). Several drug transporters, such as breast cancer resistance protein (BCRP), multidrug resistance associated proteins (MRP1, MRP2, and MRP4) are involved in the active uptake and efflux of parental oxazaphosphorines, their cytotoxic mustards and conjugates in hepatocytes and tumor cells. Oxazaphosphorine metabolism and transport have a major impact on pharmacokinetic variability, pharmacokinetic-pharmacodynamic relationship, toxicity, resistance, and drug interactions since the drug-metabolizing enzymes and drug transporters involved are key determinants of the pharmacokinetics and pharmacodynamics of oxazaphosphorines. A better understanding of the factors that affect the metabolism and transport of oxazaphosphorines is important for their optional use in cancer chemotherapy.

Insights into oxazaphosphorine resistance and possible approaches to its circumvention

The oxazaphosphorines cyclophosphamide, ifosfamide and trofosfamide remain a clinically useful class of anticancer drugs with substantial antitumour activity against a variety of solid tumors and hematological malignancies. A major limitation to their use is tumour resistance, which is due to multiple mechanisms that include increased DNA repair, increased cellular thiol levels, glutathione S-transferase and aldehyde dehydrogenase activities, and altered cell-death response to DNA damage. These mechanisms have been recently re-examined with the aid of sensitive analytical techniques, high-throughput proteomic and genomic approaches, and powerful pharmacogenetic tools. Oxazaphosphorine resistance, together with dose-limiting toxicity (mainly neutropenia and neurotoxicity), significantly hinders chemotherapy in patients, and hence, there is compelling need to find ways to overcome it. Four major approaches are currently being explored in preclinical models, some also in patients: combination with agents that modulate cellular response and disposition of oxazaphosphorines; antisense oligonucleotides directed against specific target genes; introduction of an activating gene (CYP3A4) into tumor tissue; and modification of dosing regimens. Of these approaches, antisense oligonucleotides and gene therapy are perhaps more speculative, requiring detailed safety and efficacy studies in preclinical models and in patients. A fifth approach is the design of novel oxazaphosphorines that have favourable pharmacokinetic and pharmacodynamic properties and are less vulnerable to resistance. Oxazaphosphorines not requiring hepatic CYP-mediated activation (for example, NSC 613060 and mafosfamide) or having additional targets (for example, glufosfamide that also targets glucose transport) have been synthesized and are being evaluated for safety and efficacy. Characterization of the molecular targets associated with oxazaphosphorine resistance may lead to a deeper understanding of the factors critical to the optimal use of these agents in chemotherapy and may allow the development of strategies to overcome resistance.