Human central nervous system and plasma pharmacology of mitoxantrone

Anthracyclines induce cardiotoxicity through a shared gene expression response signature

TOP2 inhibitors (TOP2i) are effective drugs for breast cancer treatment. However, they can cause cardiotoxicity in some women. The most widely used TOP2i include anthracyclines (AC) Doxorubicin (DOX), Daunorubicin (DNR), Epirubicin (EPI), and the anthraquinone Mitoxantrone (MTX). It is unclear whether women would experience the same adverse effects from all drugs in this class, or if specific drugs would be preferable for certain individuals based on their cardiotoxicity risk profile. To investigate this, we studied the effects of treatment of DOX, DNR, EPI, MTX, and an unrelated monoclonal antibody Trastuzumab (TRZ) on iPSC-derived cardiomyocytes (iPSC-CMs) from six healthy females. All TOP2i induce cell death at concentrations observed in cancer patient serum, while TRZ does not. A sub-lethal dose of all TOP2i induces limited cellular stress but affects calcium handling, a function critical for cardiomyocyte contraction. TOP2i induce thousands of gene expression changes over time, giving rise to four distinct gene expression response signatures, denoted as TOP2i early-acute, early-sustained, and late response genes, and non-response genes. There is no drug- or AC-specific signature. TOP2i early response genes are enriched in chromatin regulators, which mediate AC sensitivity across breast cancer patients. However, there is increased transcriptional variability between individuals following AC treatments. To investigate potential genetic effects on response variability, we first identified a reported set of expression quantitative trait loci (eQTLs) uncovered following DOX treatment in iPSC-CMs. Indeed, DOX response eQTLs are enriched in genes that respond to all TOP2i. Next, we identified 38 genes in loci associated with AC toxicity by GWAS or TWAS. Two thirds of the genes that respond to at least one TOP2i, respond to all ACs with the same direction of effect. Our data demonstrate that TOP2i induce thousands of shared gene expression changes in cardiomyocytes, including genes near SNPs associated with inter-individual variation in response to DOX treatment and AC-induced cardiotoxicity.

Reconsidering the route of drug delivery in refractory multiple sclerosis: Toward a more effective drug accumulation in the central nervous system

Multiple sclerosis is a chronic demyelinating disease with different disease phenotypes. The current FDA-approved disease-modifying therapeutics (DMTs) cannot cure the disease, but only alleviate the disease progression. While the majority of patients respond well to treatment, some of them are suffering from rapid progression. Current drug delivery strategies include the oral, intravenous, subdermal, and intramuscular routes, so these drugs are delivered systemically, which is appropriate when the therapeutic targets are peripheral. However, the potential benefits may be diminished when these targets sequester behind the barriers of the central nervous system. Moreover, systemic drug administration is plagued with adverse effects, sometimes severe. In this context, it is prudent to consider other drug delivery strategies improving their accumulation in the brain, thus providing better prospects for patients with rapidly progressing disease course. These targeted drug delivery strategies may also reduce the severity of systemic adverse effects. Here, we discuss the possibilities and indications for reconsideration of drug delivery routes (especially for those "non-responding" patients) and the search for alternative drug delivery strategies. More targeted drug delivery strategies sometimes require quite invasive procedures, but the potential therapeutic benefits and reduction of adverse effects could outweigh the risks. We characterized the major FDA-approved DMTs focusing on their therapeutic mechanism and the potential benefits of improving the accumulation of these drugs in the brain.

The blood-tumour barrier in cancer biology and therapy

The protective blood-brain barrier has a major role in ensuring normal brain function by severely limiting and tightly controlling the ingress of substances into the brain from the circulation. In primary brain tumours, such as glioblastomas, as well as in brain metastases from cancers in other organs, including lung and breast cancers and melanoma, the blood-brain barrier is modified and is referred to as the blood-tumour barrier (BTB). Alterations in the BTB affect its permeability, and this structure participates in reciprocal regulatory pathways with tumour cells. Importantly, the BTB typically retains a heterogeneous capacity to restrict the penetration of many therapeutic agents into intracranial tumours, and overcoming this challenge is a key to improving the effectiveness of treatment and patient quality of life. Herein, current knowledge of BTB structure and function is reviewed from a cell and cancer biology standpoint, with a focus on findings derived from in vivo models and human tumour specimens. Additionally, how this knowledge can be translated into clinical advances for patients with cancer is discussed.

Tumor pharmacokinetics and pharmacodynamics of the CDK4/6 inhibitor ribociclib in patients with recurrent glioblastoma

INTRODUCTION

We conducted a phase Ib study (NCT02345824) to determine whether ribociclib, an inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), penetrates tumor tissue and modulates downstream signaling pathways including retinoblastoma protein (Rb) in patients with recurrent glioblastoma (GBM).

METHODS

Study participants received ribociclib (600 mg QD) for 8-21 days before surgical resection of their recurrent GBM. Total and unbound concentrations of ribociclib were measured in samples of tumor tissue, plasma, and cerebrospinal fluid (CSF). We analyzed tumor specimens obtained from the first (initial/pre-study) and second (recurrent/on-study) surgery by immunohistochemistry for Rb status and downstream signaling of CDK4/6 inhibition. Participants with Rb-positive recurrent tumors continued ribociclib treatment on a 21-day-on, 7-day-off schedule after surgery, and were monitored for toxicity and disease progression.

RESULTS

Three participants with recurrent Rb-positive GBM participated in this study. Mean unbound (pharmacologically active) ribociclib concentrations in plasma, CSF, MRI-enhancing, MRI-non-enhancing, and tumor core regions were 0.337 μM, 0.632 μM, 1.242 nmol/g, 0.484 nmol/g, and 1.526 nmol/g, respectively, which exceeded the in vitro IC₅₀ (0.04 μM) for inhibition of CDK4/6 in cell-free assay. Modulation of pharmacodynamic markers of ribociclib CDK 4/6 inhibition in tumor tissues were inconsistent between study participants. No participants experienced serious adverse events, but all experienced early disease progression.

CONCLUSIONS

This study suggests that ribociclib penetrated recurrent GBM tissue at concentrations predicted to be therapeutically beneficial. Our study was unable to demonstrate tumor pharmacodynamic correlates of drug activity. Although well tolerated, ribociclib monotherapy seemed ineffective for the treatment of recurrent GBM.

Emerging small-molecule treatments for multiple sclerosis: focus on B cells

Multiple sclerosis (MS) is a major cause of disability in young adults. Following an unknown trigger (or triggers), the immune system attacks the myelin sheath surrounding axons, leading to progressive nerve cell death. Antibodies and small-molecule drugs directed against B cells have demonstrated good efficacy in slowing progression of the disease. This review focusses on small-molecule drugs that can affect B-cell biology and may have utility in disease management. The risk genes for MS are examined from the drug target perspective. Existing small-molecule therapies for MS with B-cell actions together with new drugs in development are described. The potential for experimental molecules with B-cell effects is also considered. Small molecules can have diverse actions on B cells and be cytotoxic, anti-inflammatory and anti-viral. The current B cell-directed therapies often kill B-cell subsets, which can be effective but lead to side effects and toxicity. A deeper understanding of B-cell biology and the effect on MS disease should lead to new drugs with better selectivity, efficacy, and an improved safety profile. Small-molecule drugs, once the patent term has expired, provide a uniquely sustainable form of healthcare.

Is the blood-brain barrier really disrupted in all glioblastomas? A critical assessment of existing clinical data

The blood-brain barrier (BBB) excludes the vast majority of cancer therapeutics from normal brain. However, the importance of the BBB in limiting drug delivery and efficacy is controversial in high-grade brain tumors, such as glioblastoma (GBM). The accumulation of normally brain impenetrant radiographic contrast material in essentially all GBM has popularized a belief that the BBB is uniformly disrupted in all GBM patients so that consideration of drug distribution across the BBB is not relevant in designing therapies for GBM. However, contrary to this view, overwhelming clinical evidence demonstrates that there is also a clinically significant tumor burden with an intact BBB in all GBM, and there is little doubt that drugs with poor BBB permeability do not provide therapeutically effective drug exposures to this fraction of tumor cells. This review provides an overview of the clinical literature to support a central hypothesis: that all GBM patients have tumor regions with an intact BBB, and cure for GBM will only be possible if these regions of tumor are adequately treated.

Mitoxantrone is More Toxic than Doxorubicin in SH-SY5Y Human Cells: A 'Chemobrain' In Vitro Study

The potential neurotoxic effects of anticancer drugs, like doxorubicin (DOX) and mitoxantrone (MTX; also used in multiple sclerosis), are presently important reasons for concern, following epidemiological data indicating that cancer survivors submitted to chemotherapy may suffer cognitive deficits. We evaluated the in vitro neurotoxicity of two commonly used chemotherapeutic drugs, DOX and MTX, and study their underlying mechanisms in the SH-SY5Y human neuronal cell model. Undifferentiated human SH-SY5Y cells were exposed to DOX or MTX (0.13, 0.2 and 0.5 μM) for 48 h and two cytotoxicity assays were performed, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) reduction and the neutral red (NR) incorporation assays. Phase contrast microphotographs, Hoechst, and acridine orange/ethidium bromide stains were performed. Mitochondrial membrane potential was also assessed. Moreover, putative protective drugs, namely the antioxidants N-acetyl-l-cysteine (NAC; 1 mM) and 100 μM tiron, the inhibitor of caspase-3/7, Ac-DEVD-CHO (100 μM), and a protein synthesis inhibitor, cycloheximide (CHX; 10 nM), were tested to prevent DOX- or MTX-induced toxicity. The MTT reduction assay was also done in differentiated SH-SY5Y cells following exposure to 0.2 μM DOX or MTX. MTX was more toxic than DOX in both cytotoxicity assays and according to the morphological analyses. MTX also evoked a higher number of apoptotic nuclei than DOX. Both drugs, at the 0.13 μM concentration, caused mitochondrial membrane potential depolarization after a 48-h exposure. Regarding the putative neuroprotectors, 1 mM NAC was not able to prevent the cytotoxicity caused by either drug. Notwithstanding, 100 μM tiron was capable of partially reverting MTX-induced cytotoxicity in the NR uptake assay. One hundred μM Ac-DEVD-CHO and 10 nM cycloheximide (CHX) also partially prevented the toxicity induced by DOX in the NR uptake assay. MTX was more toxic than DOX in differentiated SH-SY5Y cells, while MTX had similar toxicity in differentiated and undifferentiated SH-SY5Y cells. In fact, MTX was the most neurotoxic drug tested and the mechanisms involved seem dissimilar among drugs. Thus, its toxicity mechanisms need to be further investigated as to determine the putative neurotoxicity for multiple sclerosis and cancer patients.

High content screening of patient-derived cell lines highlights the potential of non-standard chemotherapeutic agents for the treatment of glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most common primary brain malignancy in adults, yet survival outcomes remain poor. First line treatment is well established, however disease invariably recurs and improving prognosis is challenging. With the aim of personalizing therapy at recurrence, we have established a high content screening (HCS) platform to analyze the sensitivity profile of seven patient-derived cancer stem cell lines to 83 FDA-approved chemotherapy drugs, with and without irradiation.

METHODS

Seven cancer stem cell lines were derived from patients with GBM and, along with the established cell line U87-MG, each patient-derived line was cultured in tandem in serum-free conditions as adherent monolayers and three-dimensional neurospheres. Chemotherapeutics were screened at multiple concentrations and cells double-stained to observe their effect on both cell death and proliferation. Sensitivity was classified using high-throughput algorithmic image analysis.

RESULTS

Cell line specific drug responses were observed across the seven patient-derived cell lines. Few agents were seen to have radio-sensitizing effects, yet some drug classes showed a marked difference in efficacy between monolayers and neurospheres. In vivo validation of six drugs suggested that cell death readout in a three-dimensional culture scenario is a more physiologically relevant screening model and could be used effectively to assess the chemosensitivity of patient-derived GBM lines.

CONCLUSION

The study puts forward a number of non-standard chemotherapeutics that could be useful in the treatment of recurrent GBM, namely mitoxantrone, bortezomib and actinomycin D, whilst demonstrating the potential of HCS to be used for personalized treatment based on the chemosensitivity profile of patient tumor cells.

The Treatment of Melanoma Brain Metastases

Melanoma is the malignancy with the highest rate of dissemination to the central nervous system once it metastasizes. Until recently, the prognosis of patients with melanoma brain metastases (MBM) was poor. In recent years, however, the prognosis has improved due to high-resolution imaging that facilitates early detection of small asymptomatic brain metastases and early intervention with local modalities such as stereotactic radiosurgery. More recently, a number of systemic therapies have been approved by the Food and Drug Administration for metastatic melanoma, resulting in improved survival for many MBM patients. Registration trials for these newer therapies excluded patients with untreated brain metastases, and a number of studies specifically tailored to this population of patients have been conducted or are underway. Herein, we review contemporary locoregional and systemic therapies and describe the unique challenges posed by treatment of brain metastases, such as radionecrosis, cerebral edema, and pseudoprogression. Since the number of systemic and combined modality clinical trials has increased, we expect that the treatment landscape for patients with melanoma brain metastasis will change dramatically. In addition to ongoing clinical trials, which show great promise, we conclude that our understanding of intracranial metastasis remains quite limited. In addition to inter-disciplinary, multi-modality studies, bench-side work to better understand the process of cerebrotropism is needed to fuel more drug development and further improve outcomes.

Intra-arterial mitoxantrone delivery in rabbits: an optical pharmacokinetic study

BACKGROUND

Several human studies have demonstrated the feasibility of intra-arterial delivery of mitoxantrone in systemic malignancies. Computational models predict that an intra-arterial bolus injection of mitoxantrone during transient cerebral hypoperfusion will enhance brain tissue drug deposition in comparison with injections during normal blood flow.

OBJECTIVE

To assess whether transient reduction in cerebral blood flow would enhance the delivery of mitoxantrone. This is accomplished by obtaining real-time measurements of mitoxantrone concentrations in brain tissues by using a novel optical pharmacokinetics technique, based on reflectance spectroscopy.

METHODS

The blood-brain barrier of anesthetized rabbits was disrupted by intracarotid injection of mannitol (8 mL, 25% over 40 seconds). Thereafter, animals received 3 mg of mitoxantrone injection during normal perfusion (n = 5) or cerebral hypoperfusion that was induced by contralateral arterial occlusion and systemic hypotension (n = 8).

RESULTS

Cerebral hypoperfusion significantly decreased the cerebral blood flow, allowing a longer exposure time of the drug. It was determined that therapeutic concentrations of mitoxantrone were achieved in both groups; however, hypoperfusion did not increase the tissue concentrations of mitoxantrone after 20 minutes.

CONCLUSION

These results demonstrate the effective delivery of mitoxantrone by the intra-arterial route, after blood-brain-barrier disruption, but the predicted benefits of flow reduction for improving intra-arterial deposition of mitoxantrone was not evident.

Tissue concentration of systemically administered antineoplastic agents in human brain tumors

The blood-brain-barrier (BBB) limits the penetration of many systemic antineoplastic therapies. Consequently, many agents may be used in clinical studies and clinical practice though they may not achieve therapeutic levels within the tumor. We sought to compile the currently available human data on antineoplastic drug concentrations in brain and tumor tissue according to BBB status. A review of the literature was conducted for human studies providing concentrations of antineoplastic agents in blood and metastatic brain tumors or high-grade gliomas. Studies were considered optimal if they reported simultaneous tissue and blood concentration, multiple sampling times and locations, MRI localization, BBB status at sampling site, tumor histology, and individual subject data. Twenty-Four studies of 19 compounds were included. These examined 18 agents in contrast-enhancing regions of high-grade gliomas, with optimal data for 2. For metastatic brain tumors, adequate data was found for 9 agents. Considerable heterogeneity was found in the measurement value, tumor type, measurement timing, and sampling location within and among studies, limiting the applicability of the results. Tissue to blood ratios ranged from 0.054 for carboplatin to 34 for mitoxantrone in high-grade gliomas, and were lowest for temozolomide (0.118) and etoposide (0.116), and highest for mitoxantrone (32.02) in metastatic tumors. The available data examining the concentration of antineoplastic agents in brain and tumor tissue is sparse and limited by considerable heterogeneity. More studies with careful quantification of antineoplastic agents in brain and tumor tissue is required for the rational development of therapeutic regimens.

The blood-brain barrier and cancer: transporters, treatment, and Trojan horses

Despite scientific advances in understanding the causes and treatment of human malignancy, a persistent challenge facing basic and clinical investigators is how to adequately treat primary and metastatic brain tumors. The blood-brain barrier is a physiologic obstruction to the delivery of systemic chemotherapy to the brain parenchyma and central nervous system (CNS). A number of physiologic properties make the endothelium in the CNS distinct from the vasculature found in the periphery. Recent evidence has shown that a critical aspect of this barrier is composed of xenobiotic transporters which extrude substrates from the brain into the cerebrospinal fluid and systemic circulation. These transporters also extrude drugs and toxins if they gain entry into the cytoplasm of brain endothelial cells before they enter the brain. This review highlights the properties of the blood-brain barrier, including the location, function, and relative importance of the drug transporters that maintain this barrier. Primary and metastatic brain malignancy can compromise this barrier, allowing some access of chemotherapy treatment to reach the tumor. The responsiveness of brain tumors to systemic treatment found in past clinical research is discussed, as are possible explanations as to why CNS tumors are nonetheless able to evade therapy. Finally, strategies to overcome this barrier and better deliver chemotherapy into CNS tumors are presented.

Surgifoam and mitoxantrone in the glioblastoma multiforme postresection cavity: the first step of locoregional chemotherapy through an ad hoc-placed catheter: technical note

OBJECTIVE

To investigate the safety and feasibility of a novel form of treatment offered by the direct intraoperative application of a Surgifoam-mitoxantrone mix into a glioblastoma multiforme postresection cavity. A technique for the placement of an intracavity catheter connected with a subcutaneous reservoir for further locoregional mitoxantrone administration is also described.

METHODS

Between January and December 2004, 22 consecutive recurrent glioblastoma multiforme patients (14 men, 8 women; age, 56-72 yr; average, 64 yr; median, 65 yr) were enrolled in this study. All patients underwent image-assisted gross total resection of the pathological tissue. A Surgifoam-mitoxantrone mix (1 g Surgifoam powder, 3 ml physiological solution, and 12 mg mitoxantrone in 6 ml) was used to fill the surgical cavity. A ventricular catheter, connected to a Rickham subcutaneous reservoir, was then positioned in the surgical cavity for future mitoxantrone administration.

RESULTS

Toxic effects caused by mitoxantrone administration were not observed in any patients during the first postoperative month. On postoperative Days 1, 7, and 30, computed tomographic scans excluded surgical complications. In three patients, residual tumor was disclosed.

CONCLUSION

A mix of Surgifoam and mitoxantrone could be safely applied intraoperatively into the post-glioblastoma multiforme resection cavity without any observable side effects. This technique may benefit both the surgeon and the patient by taking advantage of the drug's hemostatic and cytostatic properties.

Systemic temozolomide combined with loco-regional mitoxantrone in treating recurrent glioblastoma

Twenty-two recurrent GBM patients were enrolled for second tumor debulking with local positioning of a Rickam reservoir, in order to locally deliver chemotherapy with the aim of controlling local tumor recurrence. We designed a protocol using systemic temozolomide (150 mg/sqm days 1-5 every 28) in association with mitoxantrone, delivered through the reservoir (4 mg/day 1-5 every 28) positioned into the area of tumor exeresis. After re-operation a residual tumor mass no larger than 2 cm was identified in 18/22 patients. The patients were treated with monthly cycles of chemotherapy until evolution of the tumor, but in no case for more than 10 cycles. Responses were evaluated by MRI scans performed every 2 months and images assessed according to MacDonald's criteria. Response rate: no complete responses (CR), 5 partial responses (PR), 13 stable disease (SD) and 4 progressive disease (PD) occurred. The median progression-free survival (PFS) and survival time (ST) of the whole group of treated patients was 7 and 11 months, respectively and more than a quarter of the patients survived over 18 months. During the study, the patients' compliance was complete and no dropouts occurred. Hematological toxicity was mild and after repeated local injections only minor neurological side-effects occurred. Despite some bias in patients' selection not excluded in this pilot study, results are interesting: the PFS was as long as the survival of recurrent GBM reported in the literature.

Intratumoral delivery of mitoxantrone in association with 90-Y radioimmunotherapy (RIT) in recurrent glioblastoma

Twenty-six recurrent Glioblastoma (rGBM) patients sequentially treated at the National Neurological Institute 'C Besta' were enrolled for a second surgery in order to remove recurrent tumor and to place an Ommaya reservoire to allow local delivery of chemotherapy and local pre-targeted radio-immunotherapy (RIT). All patients had partial tumor resection and 75% of them had a residual tumor mass after exeresis larger than 2 cm. After surgery all patients were managed with a second line systemic chemotherapy (PCV). Moreover the protocol scheduled two cycles of local RIT (90 Yttrium 5- 25 mCi per cycle) with a 10 week interval. Locoregional mitoxantrone chemotherapy was locally delivered as a single dose of 4 mg every 20 days. Responses to treatment were assessed by monthly neurological examination and by MRI or contrast-enhanced CT scan performed every 2 months. For the whole group of patients the PFS after second surgery at 6 and 12 months was 61% and 22%, respectively and survival after recurrence at 6, 12 and 18 months was 80%, 53% and 42%, respectively. Neither major side effects occurred systemically nor related on the place of local injections. The percentage of long-term survivors was very high: 42% of patients were still alive at 18 months. We stress the concept that the combined treatments could be more effective if delivered into a smaller residual tumor mass and probably in an adjuvant setting, before tumour recurrence.

Intratumoral doxorubicin in patients with malignant brain gliomas

The objective of the study was to evaluate the safety and therapeutic efficacy of intralesional administration of doxorubicin in brain gliomas. Ten patients with recurrent grade III or IV glioma were enrolled in the study, after the second operation. All patients had not responded to radiation therapy. Chemotherapy was administered directly in the tumor through an Ommaya pump placed in the site of disease at the time of craniotomy. Doxorubicin 0.5 mg was administered in the Ommaya reservoir every 24 hours on days 1 to 10. Patients were evaluated at 6- to 8-week intervals until tumor progression and death. All patients were evaluated for response. Six of 10 patients had clinical improvement lasting from 12 to 73 weeks. Objective radiologic response was observed in 5 of 10 (50%) patients. One patient achieved complete response with time to disease progression of 119 weeks, and 4 patients had a partial response (duration 14-39 weeks) with 25% or more reduction of tumor volume on computed tomography scan compared with pretreatment measurements. Time to disease progression in patients who responded after the intratumoral chemotherapy was 39.83 +/- 40.5 weeks. One additional patient had stable disease for a duration of 12 weeks. The median survival of the patients with response was 55.17 +/- 54.22 weeks (range: 21-164 weeks), whereas survival of those who did not respond was 17.0 +/- 12.36 weeks (range: 8-35) (Mann Whitney U test: z = -2.13, p = 0.033). The median survival of all 10 patients was 39.9 +/- 45.52 weeks (range: 8-73 weeks). Bifrontal headache was reported in 4 of 10 patients immediately after the administration of doxorubicin. There were no other clinically significant adverse reactions either in the brain or systematically. Intralesional administration of doxorubicin appears to be a safe and effective treatment and should be further explored in the management of brain gliomas resistant to conventional forms of treatment.

Efficacy of intratumoral delivery of mitoxantrone in recurrent malignant glial tumours

Ninety-nine patients bearing recurrent malignant glioma sequentially selected according to strict eligibility criteria (72 GBL and 27 AA) entered the study. All patients were previously managed with radiotherapy 60 Gy total dose and chemotherapy with nitrosoureas and platinum compounds. At recurrence they were subdivided in homogeneous groups, all treated with the same systemic chemotherapy protocol: 27 GBL (group A) only systemically treated, 20 GBL (group B) treated also locally by delivering 4mg of mitoxantrone every 20 days through the Ommaya reservoire, and 25 GBL (group C) treated with a second surgery and locally as group B. Of the AA group, 13/27 were treated locally trough the Ommaya reservoir after repeat surgery. A trend to different demographic features among subgroups (with locoregionally treated patients and patients undergoing repeat surgery being younger than the others) was seen in this non-randomized study, but this was not statistically significant. Median overall survival was 27, 26 and 15.5 months respectively for groups c, b and a (log-rank = 0.1). After tumor recurrence median survival was 16.8, 12 and 6.6 months respectively for groups c, b and a (log-rank = 0.001) For the 29 AA, overall survival was 48.5 and 100 months (log-rank = 0.03) if treated locally with second tumor debulking. Our results stress the opinion that a second operation could be indicated only if it is a part of a therapeutic protocol to allow a locoregional treatment. Moreover we can finally assume that local delivery of chemotherapy after tumor recurrence, possibly extends patients survival but certainly improves the number of long-survivors.

The blood-brain barrier and oncology: new insights into function and modulation

The efficacy of chemotherapy for malignant primary or metastatic brain tumours is still poor. This is at least partly due to the presence of the blood-brain barrier (BBB). The functionality of the BBB can be explained by physicochemical features and efflux pump mechanisms. An overview of the literature is presented with emphasis on oncology. The BBB consists of capillary endothelial cells that lack fenestrations and are connected together with continuous tight junctions, with a high electrical resistance. Permeability of tight junctions can be increased in vitro by contraction of the cytoskeleton, caused by bradykinin agonists. Different efflux pumps are present in the BBB. Examples are P-glycoprotein (P-gp), organic anion transporters, (OAT) and multidrug-resistance-associated proteins (MRP)(1 and 3). These pumps act as a multi-specific efflux pump for various chemotherapeutic drugs. Experiments have shown that P-gp can be inhibited by different non-chemotherapeutic substrates such as cyclosporin A. The functionality in vivo of P-gp can be measured with positron emission tomography and [(11)C]-verapamil or with single photon emission computer tomography and(99m)Tc-sestamibi. MRP(1)and MRP(3)act as organic anion transporters that in vitro act as efflux pumps for substances that are conjugated or co-transported with glutathione and glucuronide, respectively. Methotrexate has been recently demonstrated to be transported by MRP(1)and MRP(3). Results of studies which demonstrate the clinical relevance and applicability of BBB modulators are eagerly awaited.

Chemotherapy for brain metastases of lung cancer: a review

In lung cancer patients brain metastases develop with a high frequency. For years radiotherapy has been the standard treatment for these patients. Here we review the experience with chemotherapy for brain metastases in lung cancer patients. The concept of the brain as pharmacological sanctuary site when brain metastases are present is challenged and it is argued that chemotherapy does play a role in this situation. Recent clinical trials indicate that the combination of chemotherapy and radiotherapy may become the standard treatment for lung cancer patients with brain metastases. It is unclear whether for micrometastatic disease to the brain, blood brain barrier function is of importance for the outcome of chemotherapy in lung cancer patients with respect to the development of overt brain metastases. Areas of improvement of delivery of cytotoxic agents to the brain when brain metastases have not yet developed are discussed.

Mitoxantrone-induced DNA strand breaks in cell-cultures of malignant human astrocytoma and glioblastoma tumors

In this study mitoxantrone (Mtx) induced DNA strand breaks were measured with the alkaline elution technique in short term cell cultures derived from human gliomas. Glioblastomas or astrocytomas from 5 patients who underwent intracranial surgery were cultured and incubated i h with different concentrations of Mtx (0, 0.01, 0.1 and 1.0 microgram/ml). The alkaline elution method was modified to measure DNA lesions in human gliomas. Mtx induced DNA strand breaks in a dose dependent manner in all cell cultures tested. There was a linear increase of DNA strand break frequency induced by Mtx between 0.01-1.0 microgram/ml. concerning these in vitro data, Mtx might be potentially useful for the treatment of patients with malignant brain tumors.

Interstitial chemotherapy with mitoxantrone in recurrent malignant glioma: preliminary data

We undertook a phase I-II trail of loco-regional mitoxantrone in 12 patients affected by malignant gliomas. Mitoxantrone was delivered at tumor recurrence by Ommaya reservoir, with 2 cycles and a 1 month interval between each cycle, in conjunction with systemic chemotherapy (8 pts) or not (4 pts). Treatment tolerability was good, and 9 of the patients showed either response or stable disease at the end of the treatment schedule. Regardless of associated chemotherapy, time to further tumor progression was at 6 months. A combination of early systemic and loco-regional chemotherapy with surgery and radiotherapy seems worth while pursuing in the therapeutic approach to malignant gliomas.

Cisplatin and radiation in the treatment of tumors of the central nervous system: pharmacological considerations and results of early studies

PURPOSE

To review the human central nervous system pharmacology of cisplatin, factors that affect cisplatin uptake in tumors, and use alone and with radiation for the treatment of primary brain tumors.

METHODS AND MATERIALS

The authors review their own prior published and unpublished experience and data published by other groups on the above issues.

RESULTS

Cisplatin is one of the most active chemotherapy drugs available for the treatment of solid tumors. It is synergistic with several other agents, including radiation. While it attains only low concentrations in the normal central nervous system, concentrations and plasma-tissue transfer constants for human intracerebral tumors are comparable to those in extracerebral tumors. Tumor type appears to be a more important determinant of platinum concentration than is tumor location, and gliomas do achieve lower concentrations than do other intracerebral or extracerebral tumors. Several other factors have also been identified that correlate with concentrations of cisplatin achieved in human tumors. While cisplatin alone and in combination with other drugs does have some degree of efficacy against primary brain tumors, combining it with cranial irradiation has generally not resulted in any substantial improvement in outcome to date, although some individual studies have been somewhat encouraging. New approaches are currently under investigation.

CONCLUSION

Human pharmacology studies provide a rationale for use of cisplatin in the treatment of human brain tumors, and human and in vitro studies suggest some manipulations that might potentially further augment tumor platinum concentrations. While clinical studies suggest that cisplatin combinations may be of some value vs. human primary brain tumors and brain metastases, and while in vitro studies suggest that cisplatin potentiates radiation efficacy, no combination of cisplatin plus radiation yet tested has appeared to be superior to radiation alone.

A critique of the role of the blood-brain barrier in the chemotherapy of human brain tumors

There is general agreement that most chemotherapy agents achieve only relatively low concentrations in the normal central nervous system, that the blood-brain barrier is variably disrupted in malignant brain tumors, and that the concentration of chemotherapy drugs in the brain adjacent to tumor is intermediate between concentrations achieved in brain tumors vs normal brain. However, there is substantial controversy regarding the role of the blood-brain barrier in resistance to chemotherapy of intracerebral tumors. Many chemotherapy agents achieve concentrations in brain tumors that are comparable to those in extracerebral tumors, and drugs that cross the intact blood-brain barrier only poorly may be active against intracerebral tumors. Furthermore, the hypothesis that the brain is a pharmacological sanctuary where metastases may grow while tumor is responding in other parts of the body may be flawed: there are only 2 or 3 types of malignancies (out of all those that are sensitive to chemotherapy) in which the risk of isolated central nervous system relapse is moderately high, and even in these 2 or 3, effective central nervous system prophylaxis has minimal or no impact on overall survival. Furthermore, drugs that cross the BBB do not appear to be more effective than other drugs at reducing the risk of brain metastases, and brain metastases at the time of diagnosis do not necessarily convey a worse prognosis than metastases to various other sites. While average drug concentrations in brain adjacent to tumor are lower than those within brain tumors, very small numbers of tumor cells may be capable of inducing local leakiness in blood vessels, and there is little information on drug concentrations achieved in individual tumor cells within the brain adjacent to tumor. Furthermore, any limitation of uptake of drugs into brain tumors could be at least partially due to increased tissue pressure within tumors rather than being due to blood-brain barrier phenomena. This distinction could be important, since strategies that one might use to increase drug delivery to brain tumors might differ depending on whether the reduced delivery were due to barrier phenomena vs blood flow phenomena. The role of the blood-brain barrier in resistance of intracerebral tumors to chemotherapy remains unclear: while it may well play some role (and perhaps even a major one), self-fulfilling prophecies and unintentional bias in data selection and interpretation may have previously made it appear more important than it actually is.(ABSTRACT TRUNCATED AT 400 WORDS)

Control of immune-mediated disease of the central nervous system requires the use of a neuroactive agent: elucidation by the action of mitoxantrone

Mitoxantrone was used as an immunosuppressive probe to elucidate a means for the control of experimental allergic encephalomyelitis (EAE) induced in Biozzi AB/H mice following injection of spinal cord homogenate emulsified in Freund's adjuvant. A single i.p. injection of 2.5 mg/kg of mitoxantrone, 1-2 days before the anticipated onset of EAE, failed to prevent the majority of animals from developing clinical disease, whereas when the compound was injected directly into the central nervous system (CNS), at this time point, significantly increased therapeutic benefit was evident, with most animals failing to develop clinical EAE. Although the clinical use of intrathecal mitoxantrone is strongly contraindicated, these data suggest that increased therapeutic benefit may be achieved in immune-mediated disease of the CNS by targeting immunosuppressive doses of suitable agents, on lymphocyte activation within the CNS. In addition, direct administration of immunosuppressive doses into the CNS may reduce potentially unwanted (side) effects in the periphery.

The MTT assay for chemosensitivity testing of human tumors of the central nervous system. Part II: Evaluation of patient- and drug-specific variables

In this study we assessed the influence of patient- and drug-specific parameters in the short-term MTT-chemosensitivity assay in 150 primary cell cultures derived from human brain tumors. In 45 patients the MTT assay was directly compared with the CFA (Colony Forming Assay). Resistance was 10-20% higher in the MTT assay than in the CFA, but there was a good agreement in both assays, that more malignant gliomas had a higher in vitro chemosensitivity against ACNU and BCNU. Overall the results demonstrate, that there is no uniform correlation between the in vitro chemosensitivity and the histopathological classification of the tumors, which corresponds well to the clinical situation. On the basis of this study we suggest prospective clinical trials with the MTT assay in human brain tumors.

Do anticancer agents reach the tumor target in the human brain?

The development of effective chemotherapy for tumors of the central nervous system (CNS) is complicated in that the blood-brain barrier (BBB) hampers the penetration of most drugs into the brain and cerebrospinal fluid (CSF). This review summarizes the main reports on the distribution to CNS tumors and peritumoral normal brain of antitumor agents such as epipodophyllotoxins, cis-diamminedichloroplatinum(II), some nitrosoureas, bleomycin, vinblastine, and other clinically used antitumor agents as well as that of some experimental compounds with specific physicochemical properties. Drug levels were measured at surgical resection or in autopsy samples taken from patients who presented with different primary brain tumors or with brain metastases from extracerebral tumors. The observations made in each study were summarized in some detail, and the main points were then evaluated comparatively so as to highlight common aspects in the pharmacokinetic patterns of antitumor agents in human CNS tumors. Independently of their physicochemical properties, most antitumor agents appear to accumulate to a greater extent and to persist longer in intracerebral tumors than in the normal peritumoral brain. From in vitro cytotoxicity assays, it appears that epipodophyllotoxins, platinum compounds, bleomycin, and nitrosoureas reach potentially active therapeutic concentrations at the tumor target. However, all drugs have difficulty in reaching brain tissue adjacent to the tumor, as the intact BBB hampers their penetration. Plasma and CSF drug concentrations usually give little useful indication of the absolute quantity of drugs in brain tumors. To obtain a clear understanding of the CNS distribution of antitumor agents, one must determine whether the compound being measured is actually responsible for the observed activity and must consider the role of metabolites in the effect of the parent drug.

Mitoxantrone. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in the chemotherapy of cancer

Mitoxantrone is a dihydroxyanthracenedione derivative which as intravenous mono- and combination therapy has demonstrated therapeutic efficacy similar to that of standard induction and salvage treatment regimens in advanced breast cancer, non-Hodgkin's lymphoma, acute nonlymphoblastic leukaemia and chronic myelogenous leukaemia in blast crisis; it appears to be an effective alternative to the anthracycline component of standard treatment regimens in these indications. Mitoxantrone is also effective as a component of predominantly palliative treatment regimens for hepatic and advanced ovarian carcinoma. Limited studies suggest useful therapeutic activity in multiple myeloma and acute lymphoblastic leukaemia. Regional therapy of malignant effusions, hepatic and ovarian carcinomas has also been very effective, with a reduction in systemic adverse effects. Mitoxantrone inhibits DNA synthesis by intercalating DNA, inducing DNA strand breaks, and causing DNA aggregation and compaction, and delays cell cycle progression, particularly in late S phase. In vitro antitumour activity is concentration- and exposure time-proportional, and synergy with other antineoplastic drugs has been demonstrated in murine tumour models. Leucopenia may be dose-limiting in patients with solid tumours, whereas stomatitis may be dose-limiting in patients with leukaemia. Other adverse effects are usually of mild or moderate severity although cardiac effects, particularly congestive heart failure, may be of concern, especially in patients with a history of anthracycline therapy, mediastinal irradiation or cardiovascular disease. Mitoxantrone displays an improved tolerability profile compared with doxorubicin and other anthracyclines, although myelosuppression may occur more frequently. Thus, mitoxantrone is an effective and better tolerated alternative to the anthracyclines in most haematological malignancies, in breast cancer and in advanced hepatic or ovarian carcinoma. Further studies may consolidate its role in the treatment of these and other malignancies.

Concentrations of VP16 and VM26 in human brain tumors

VP16 and VM26 were determined by high pressure liquid chromatography in intracerebral tumors, adjacent normal brain tissue, plasma and CSF samples from 24 patients given the two drugs before surgical resection of the tumor. The drugs were administered at doses of 100-150 mg/m2 as a 1-hour i.v. infusion, between 1.5 and 12 hours before surgery. Concentrations of VP16 ranged between 1.05 and 3.28 micrograms/g in tumors in the series of patients who received the drug 1.5-3 hours before surgery and between less than 0.05 and 1.12 micrograms/g in four patients who received the drug 9-13 hours before surgery. Tumor concentrations of VM26 also varied, ranging from less than 0.05 to 1.68 micrograms/g between 1.5 and 12 hours before surgery. VP16 and VM26 in the apparently normal brain tissue surrounding the tumor were low or undetectable except in one patient who had received radiotherapy, in whom we found 3.1 micrograms/g.

Phase I and pharmacology study of intravesical mitoxantrone for recurrent superficial bladder tumors

A phase 1 study of intravesical mitoxantrone was done in patients with superficial bladder tumors recurrent after previous intravesical therapy. Mitoxantrone (5 to 10.5 mg.) was instilled in the bladder via catheter and was left in situ for 2 hours. Each patient received 6 treatments at 1-week intervals. Pharmacology studies were conducted in a subset of consenting patients. Dysuria, urinary frequency and hematuria were dose-limiting at 10 to 10.5 mg., the dose recommended for our phase 2 studies. One patient treated with 7.5 mg. mitoxantrone had bladder contracture after severe bladder injury caused by the drug. The interval free of recurrence increased in 5 of 8 patients treated with 10 to 10.5 mg. mitoxantrone and in 6 of 19 treated at lower dose levels. One patient who had residual evaluable tumor in the bladder at treatment experienced a complete remission for 16 months. Only 1 of 18 patients who underwent pharmacology studies had any mitoxantrone detectable in the blood after intravesical administration. This patient had severe irritative symptoms at treatment. No systemic toxicity was noted in any patient. Of the mitoxantrone instilled into the bladder 33 to 100% (mean 75%) was recovered in the specimen voided at the end of treatment. In summary, intravesical mitoxantrone is reasonably well tolerated and should be studied further at a dose of 10 mg. per week for 6 weeks. Caution should be exercised, since bladder contracture was seen in 1 patient. Systemic absorption and toxicity are negligible.