Concentration of vinblastine in human intracerebral tumor and other tissues

Strategies to Improve Drug Delivery Across the Blood-Brain Barrier for Glioblastoma

PURPOSE OF REVIEW

Glioblastoma remains resistant to most conventional treatments. Despite scientific advances in the past three decades, there has been a dearth of effective new treatments. New approaches to drug delivery and clinical trial design are needed.

RECENT FINDINGS

We discuss how the blood-brain barrier and tumor microenvironment pose challenges for development of effective therapies for glioblastoma. Next, we discuss treatments in development that aim to overcome these barriers, including novel drug designs such as nanoparticles and antibody-drug conjugates, novel methods of drug delivery, including convection-enhanced and intra-arterial delivery, and novel methods to enhance drug penetration, such as blood-brain barrier disruption by focused ultrasound and laser interstitial thermal therapy. Lastly, we address future opportunities, positing combination therapy as the best strategy for effective treatment, neoadjuvant and window-of-opportunity approaches to simultaneously enhance therapeutic effectiveness with interrogation of on-treatment biologic endpoints, and adaptive platform and basket trials as imperative for future trial design. New approaches to GBM treatment should account for the blood-brain barrier and immunosuppression by improving drug delivery, combining treatments, and integrating novel clinical trial designs.

A phase II study of laser interstitial thermal therapy combined with doxorubicin in patients with recurrent glioblastoma

Background

The blood-brain barrier (BBB) is a major limiting factor for drug delivery in brain tumors. Laser interstitial thermal therapy (LITT) disrupts the peritumoral BBB. In this study, we examine survival in patients with recurrent glioblastoma (GBM) treated with LITT followed by low-dose doxorubicin, a potent anti-neoplastic drug with poor BBB permeability.

Methods

Forty-one patients with recurrent GBM were enrolled; thirty patients were evaluable. Participants underwent LITT followed by 6 weekly doxorubicin treatments starting within one week (Early Arm) or at 6–8 weeks (Late Arm) after LITT. The overall survival (OS), local progression-free survival (PFS), and any PFS were compared to historical controls treated with bevacizumab salvage therapy (n = 50) or LITT with standard BBB-permeable salvage therapy (n = 28). Cox proportional-hazards models examined the contribution of age, gender, MGMT promoter status, and IDH-mutation status on any PFS and OS. Adverse events were also cataloged.

Results

The Late Arm and all patients (Early Arm + Late Arm) demonstrated significant improvement in OS compared to historical controls treated with bevacizumab (p < 0.001) and LITT with standard salvage therapy (p < 0.05). No significant difference in any PFS was observed between either arm and historical controls. Low-dose doxorubicin was well tolerated with comparable adverse event rates between the arms.

Conclusions

Low-dose doxorubicin given after LITT is well tolerated and correlated with higher OS compared to historical controls treated with bevacizumab or LITT with standard salvage chemotherapy. A larger study is needed to further characterize survival and progression patterns.

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.

Targeted Therapy and Immunotherapy Response Assessment with F-18 Fluorothymidine Positron-Emission Tomography/Magnetic Resonance Imaging in Melanoma Brain Metastasis: A Pilot Study

Introduction

This pilot study aimed at exploring the utility of the proliferation tracer F-18 fluorothymidine (FLT) and positron-emission tomography (PET)/magnetic resonance imaging (MRI) (FLT–PET/MRI) for early treatment monitoring in patients with melanoma brain metastasis (MBM) who undergo targeted therapy or immunotherapy.

Material and Methods

Patients with newly diagnosed MBM underwent baseline and follow-up FLT–PET/MRI scans at 3–4 weeks of targeted therapy or immunotherapy. Up to six measurable brain lesions ≥1.0 cm per subject, as identified on T1-weighted post-gadolinium images, were included for quantitative analyses. The maximum SUV of each lesion was divided by the mean SUV of the pons to obtain the SUV ratio (SUVR).

Results

Five enrolled subjects underwent the baseline FLT–PET/MRI study in which the MBM showed a median size of 1.7 cm (range 1.0–2.9) and increased metabolic activity with SUVR of 9.9 (range 3.2–18.4). However, only two subjects (cases #1 and #2) returned for a follow-up scan. At baseline, a total of 22 lesions were analyzed in all five subjects, which showed a median size of 1.7 cm (range 1.0–2.9) and median SUVR of 9.9 (range 3.2–18.4). At follow-up, case #1 was a 55-year-old man who received targeted BRAF inhibitor and MEK inhibitor therapy with dabrafenib and trametinib. Fused PET/MRI data of six measured lesions demonstrated a significant reduction in MBM proliferative activity (median −68%; range −38 to −77%) and size (median −23%; range −4 to −55%) at three weeks of therapy. Nevertheless, the subject eventually progressed and died 13 months after therapy initiation. Case #2 was a 36-year-old man who received immunotherapy with nivolumab and ipilimumab. The five measured MBM lesions showed a mixed response at both proliferative and morphologic imaging at 1-month follow-up. Some lesions demonstrated interval decrease while others interval increase in proliferative activity with a median −44% (range −77 to +68%). On MRI, the size change was +7% (range −64 to +50%). The therapy was switched to dabrafenib and trametinib, which led to a partial response. The patient is still alive 16 months following therapy initiation.

Conclusion

The five cases presented show the potential benefit of hybrid FLT–PET/MRI for the diagnosis of MBM and treatment monitoring of targeted therapy and immunotherapy. However, further studies are required to assess their complementary role in distinguishing true progression from pseudoprogression.

TrpA1 activation in peripheral sensory neurons underlies the ionic basis of pain hypersensitivity in response to vinca alkaloids

Chemotherapy induced peripheral neuropathy (CIPN), a side effect of many anti-cancer drugs including the vinca alkaloids, is characterized by a severe pain syndrome that compromises treatment in many patients. Currently there are no effective treatments for this pain syndrome except for the reduction of anti-cancer drug dose. Existing data supports the model that the pain associated with CIPN is the result of anti-cancer drugs augmenting the function of the peripheral sensory nociceptors but the cellular mechanisms underlying the effects of anti-cancer drugs on sensory neuron function are not well described. Studies from animal models have suggested a number of disease etiologies including mitotoxicity, axonal degeneration, immune signaling, and reduced sensory innervations but these outcomes are the result of prolonged treatment paradigms and do not necessarily represent the early formative events associated with CIPN. Here we show that acute exposure to vinca alkaloids results in an immediate pain syndrome in both flies and mice. Furthermore, we demonstrate that exposure of isolated sensory neurons to vinca alkaloids results in the generation of an inward sodium current capable of depolarizing these neurons to threshold resulting in neuronal firing. These neuronal effects of vinca alkaloids require the transient receptor potential ankyrin-1 (TrpA1) channel, and the hypersensitization to painful stimuli in response to the acute exposure to vinca alkaloids is reduced in TrpA1 mutant flies and mice. These findings demonstrate the direct excitation of sensory neurons by CIPN-causing chemotherapy drugs, and identify TrpA1 as an important target during the pathogenesis of CIPN.

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.

Hyperthermic Laser Ablation of Recurrent Glioblastoma Leads to Temporary Disruption of the Peritumoral Blood Brain Barrier

BACKGROUND

Poor central nervous system penetration of cytotoxic drugs due to the blood brain barrier (BBB) is a major limiting factor in the treatment of brain tumors. Most recurrent glioblastomas (GBM) occur within the peritumoral region. In this study, we describe a hyperthemic method to induce temporary disruption of the peritumoral BBB that can potentially be used to enhance drug delivery.

METHODS

Twenty patients with probable recurrent GBM were enrolled in this study. Fourteen patients were evaluable. MRI-guided laser interstitial thermal therapy was applied to achieve both tumor cytoreduction and disruption of the peritumoral BBB. To determine the degree and timing of peritumoral BBB disruption, dynamic contrast-enhancement brain MRI was used to calculate the vascular transfer constant (Ktrans) in the peritumoral region as direct measures of BBB permeability before and after laser ablation. Serum levels of brain-specific enolase, also known as neuron-specific enolase, were also measured and used as an independent quantification of BBB disruption.

RESULTS

In all 14 evaluable patients, Ktrans levels peaked immediately post laser ablation, followed by a gradual decline over the following 4 weeks. Serum BSE concentrations increased shortly after laser ablation and peaked in 1-3 weeks before decreasing to baseline by 6 weeks.

CONCLUSIONS

The data from our pilot research support that disruption of the peritumoral BBB was induced by hyperthemia with the peak of high permeability occurring within 1-2 weeks after laser ablation and resolving by 4-6 weeks. This provides a therapeutic window of opportunity during which delivery of BBB-impermeant therapeutic agents may be enhanced.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01851733.

Delivery of molecularly targeted therapy to malignant glioma, a disease of the whole brain

Glioblastoma multiforme, because of its invasive nature, can be considered a disease of the entire brain. Despite recent advances in surgery, radiotherapy and chemotherapy, current treatment regimens have only a marginal impact on patient survival. A crucial challenge is to deliver drugs effectively to invasive glioma cells residing in a sanctuary within the central nervous system. The blood-brain barrier (BBB) restricts the delivery of many small and large molecules into the brain. Drug delivery to the brain is further restricted by active efflux transporters present at the BBB. Current clinical assessment of drug delivery and hence efficacy is based on the measured drug levels in the bulk tumour mass that is usually removed by surgery. Mounting evidence suggests that the inevitable relapse and lethality of glioblastoma multiforme is due to a failure to effectively treat invasive glioma cells. These invasive cells hide in areas of the brain that are shielded by an intact BBB, where they continue to grow and give rise to the recurrent tumour. Effective delivery of chemotherapeutics to the invasive glioma cells is therefore critical, and long-term efficacy will depend on the ability of a molecularly targeted agent to penetrate an intact and functional BBB throughout the entire brain. This review highlights the various aspects of the BBB, and also the brain-tumour-cell barrier (a barrier due to expression of efflux transporters in tumour cells), that together can significantly influence drug response. It then discusses the challenge of glioma as a disease of the whole brain, which lends emphasis to the need to deliver drugs effectively across the BBB to reach both the central tumour and the invasive glioma cells.

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.

Pharmacokinetic considerations in the treatment of CNS tumours

Despite aggressive therapy, the majority of primary and metastatic brain tumour patients have a poor prognosis with brief survival periods. This is because of the different pharmacokinetic parameters of systemically administered chemotherapeutic agents between the brain and the rest of the body. Specifically, before systemically administered drugs can distribute into the CNS, they must cross two membrane barriers, the blood-brain barrier (BBB) and blood-cerebrospinal fluid (CSF) barrier (BCB). To some extent, these structures function to exclude xenobiotics, such as anticancer drugs, from the brain. An understanding of these unique barriers is essential to predict when and how systemically administered drugs will be transported to the brain. Specifically, factors such as physiological variables (e.g. blood flow), physicochemical properties of the drug (e.g. molecular weight), as well as influx and efflux transporter expression at the BBB and BCB (e.g. adenosine triphosphate-binding cassette transporters) determine what compounds reach the CNS. A large body of preclinical and clinical research exists regarding brain penetration of anticancer agents. In most cases, a surrogate endpoint (i.e. CSF to plasma area under the concentration-time curve [AUC] ratio) is used to describe how effectively agents can be transported into the CNS. Some agents, such as the topoisomerase I inhibitor, topotecan, have high CSF to plasma AUC ratios, making them valid therapeutic options for primary and metastatic brain tumours. In contrast, other agents like the oral tyrosine kinase inhibitor, imatinib, have a low CSF to plasma AUC ratio. Knowledge of these data can have important clinical implications. For example, it is now known that chronic myelogenous leukaemia patients treated with imatinib might need additional CNS prophylaxis. Since most anticancer agents have limited brain penetration, new pharmacological approaches are needed to enhance delivery into the brain. BBB disruption, regional administration of chemotherapy and transporter modulation are all currently being evaluated in an effort to improve therapeutic outcomes. Additionally, since many chemotherapeutic agents are metabolised by the cytochrome P450 3A enzyme system, minimising drug interactions by avoiding concomitant drug therapies that are also metabolised through this system may potentially enhance outcomes. Specifically, the use of non-enzyme-inducing antiepileptic drugs and curtailing nonessential corticosteroid use may have an impact.

Cytotoxic drug sensitivity of Epstein-Barr virus transformed lymphoblastoid B-cells

BACKGROUND

Epstein-Barr virus (EBV) is the causative agent of immunosuppression associated lymphoproliferations such as post-transplant lymphoproliferative disorder (PTLD), AIDS related immunoblastic lymphomas (ARL) and immunoblastic lymphomas in X-linked lymphoproliferative syndrome (XLP). The reported overall mortality for PTLD often exceeds 50%. Reducing the immunosuppression in recipients of solid organ transplants (SOT) or using highly active antiretroviral therapy in AIDS patients leads to complete remission in 23-50% of the PTLD/ARL cases but will not suffice for recipients of bone marrow grafts. An additional therapeutic alternative is the treatment with anti-CD20 antibodies (Rituximab) or EBV-specific cytotoxic T-cells. Chemotherapy is used for the non-responding cases only as the second or third line of treatment. The most frequently used chemotherapy regimens originate from the non-Hodgkin lymphoma protocols and there are no cytotoxic drugs that have been specifically selected against EBV induced lymphoproliferative disorders.

METHODS

As lymphoblastoid cell lines (LCLs) are well established in vitro models for PTLD, we have assessed 17 LCLs for cytotoxic drug sensitivity. After three days of incubation, live and dead cells were differentially stained using fluorescent dyes. The precise numbers of live and dead cells were determined using a custom designed automated laser confocal fluorescent microscope.

RESULTS

Independently of their origin, LCLs showed very similar drug sensitivity patterns against 29 frequently used cytostatic drugs. LCLs were highly sensitive for vincristine, methotrexate, epirubicin and paclitaxel.

CONCLUSION

Our data shows that the inclusion of epirubicin and paclitaxel into chemotherapy protocols against PTLD may be justified.

Response of Asymptomatic Brain Metastases From Small-Cell Lung Cancer to Systemic First-Line Chemotherapy

Purpose

The purpose of this study was to investigate the radiologic response of asymptomatic brain metastases (BM) from small-cell lung cancer (SCLC) to first-line systemic chemotherapy.

Patients and Methods

From 1990 to 2003, 181 consecutive patients with SCLC were enrolled onto this study. Patients were examined by a neurologist on a regular basis. Magnetic resonance imaging (MRI) of the brain was performed routinely before (at diagnosis of SCLC) and after first-line systemic chemotherapy. Patients were treated with combination chemotherapy consisting of cyclophosphamide, doxorubicin, and etoposide. Clinically manifest BM were treated with whole-brain radiotherapy (WBRT). The response rate (RR) of BM was assessed by changes in the size or the number of enhanced lesions on MRI using standard criteria.

Results

Synchronous asymptomatic BM were found in 24 SCLC patients (13%). In six (27%) of the 22 assessable patients, the asymptomatic BM responded to systemic chemotherapy. A systemic response was found in 16 patients (73%). All patients became symptomatic during follow-up. The symptom-free survival did not differ between cranial responders and cranial nonresponders.

Conclusion

The RR of asymptomatic BM from SCLC to systemic chemotherapy is 27% and evidently lower than the systemic RR. Future studies should focus on the possible beneficial effect of WBRT for patients with asymptomatic synchronous BM.

Chemotherapy for metastatic tumors to the central nervous system

Management of patients with central nervous system metastases poses numerous challenges. This review focuses on the use of chemotherapy in these patients, addressing treatment difficulties such as drug resistance and possible solutions. The impact of the blood-brain barrier is considered less of a limitation than once thought. The advent of targeted signal transduction inhibitors is noted in this context. The current efficacy of chemotherapeutic agents and combinations is also discussed, with results from large studies highlighting a positive survival trend for chemotherapy in selected tumor histologies.

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.

Chemosensitivity in childhood brain tumours in vitro: evidence of differential sensitivity to lomustine (CCNU) and vincristine

The aim of this study was to examine the range of sensitivity of a panel of short-term cultures derived from different types of malignant childhood brain tumours including medulloblastoma, ependymoma and glioblastoma multiforme to three cytotoxic drugs, lomustine (CCNU), vincristine (VCR) and procarbazine (PCB). Sensitivity was assessed using a modification of the dimethylthiazolyl-2,5-diphenyl tetrazolium bromide (MTT) assay. Short-term cell lines derived from ependymomas were considerably more resistant to VCR than other types of childhood brain tumours, while cultures derived from supratentorial primitive neuroectodermal tumour (PNET) displayed marked sensitivity to both lomustine and VCR. Cultures from ependymomas, medulloblastoma and astrocytic gliomas had similar sensitivity to lomustine and PCB as cultures derived from adult malignant astrocytoma.

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.

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.

Factors affecting human autopsy kidney-cortex and kidney-medulla platinum concentrations after cisplatin administration

The objective of this study was to determine factors that affect cisplatin concentrations in human kidney cortex. We used flameless atomic absorption spectrophotometry to assay platinum in autopsy specimens of kidney cortex obtained from 83 cisplatin-treated patients. Concentrations were correlated with pretreatment factors and treatment conditions using univariate nonparametric statistics. Hierarchical stepwise multiple regression analyses of transformed (to normalize) data were then used to assess which factors were most important, controlling for other factors. Kidney-cortex platinum concentrations varied from 0 to 14.8 micrograms/g (median, 2.04 micrograms/g). The cumulative lifetime dose of cisplatin ranged from 10 to 1120 mg/m2 (median, 112 mg/m2). The time from the last cisplatin dose to death was < 1-609 days (median, 38 days). According to univariate statistics, factors that correlated (P < 0.05) with kidney-cortex platinum concentrations were the cisplatin dose per course, the pretreatment serum urea level, metoclopramide use (positive correlations), the time from the last cisplatin treatment to death, and the pretreatment serum albumin value (negative correlations). Factors that approached significance (0.05 < or = P < or = 0.10) were a history of hypertension, hyperbilirubinemia (positive), the serum calcium level, and phenytoin use (negative). In the multiple regression analysis, after controlling for the cisplatin dose per course and the time from the last treatment to death, only concurrent metoclopramide and phenytoin use entered the model. The hydration volume did not affect corrected kidney-cortex or kidney-medulla platinum concentrations. The following conclusions were reached: (1) it may be feasible to use lower hydration volumes than those used routinely, (2) any effect of hydration volume on cisplatin nephrotoxicity may not be mediated via a reduction in kidney-cortex platinum concentrations, (3) higher cisplatin doses might be tolerated with new 5-hydroxytryptamine-3 (5HT-3) antiemetics than were tolerated with metoclopramide, and (4) phenytoin should be tested for its ability to reduce cisplatin nephrotoxicity.

Human autopsy tissue distribution of the epipodophyllotoxins etoposide and teniposide

Autopsy tissues were collected from ten patients who had received etoposide, 150-3480 mg, from 1 to 412 days antemortem and from five patients who had received teniposide, 234-1577 mg, from 3 to 52 days antemortem. Tissues were assayed for etoposide and teniposide using high-pressure liquid chromatography with electrochemical detection. Etoposide was detectable in tissues of three of four patients dying < 5 days after their last etoposide treatments to cumulative doses of 150-432 (median, 280) mg but was detectable in tissues of only one of six patients dying 7-412 (median, 37) days after their last etoposide treatment to a cumulative dose of 607-3600 (median, 1553) mg. The highest tissue concentrations were in the small bowel, prostate, thyroid, bladder, spleen, and testicle. Intermediate concentrations were found in the lymph node, skeletal muscle, adrenal gland, stomach, tumor, liver, lung, pancreas, and kidney, and the lowest concentrations were found in the heart, brain, diaphragm, vagina, and esophagus. Teniposide was detectable in one patient dying 3 days after a cumulative teniposide dose of 576 mg (spleen, prostate, heart > large bowel, liver, pancreas > thyroid, adrenal, stomach, small bowel, bladder, testicle, and skeletal muscle) but was not detectable in any tissue from four patients dying 5-52 (median, 8) days after their last treatment to a cumulative teniposide dose of 234-1577 (median, 520) mg. The very short tissue half-life contrasts with our previous observations for human autopsy tissue concentrations of mitoxantrone, doxorubicin, menogaril metabolites, diaziquone, and amsacrine. The short tissue half-life may help explain the schedule dependency of epipodophyllotoxin efficacy and may also help explain the lack of visceral toxicity of these compounds.

The role of chemotherapy in the treatment of patients with brain metastases from solid tumors

Chemotherapy for brain metastases has been considered ineffective because the drugs do not penetrate the intact blood brain barrier. Alternate explanations for past failures of chemotherapy include observations that 1) many solid tumors which metastasize to brain are drug-resistant regardless of location, 2) brain metastases often occur following failure of primary chemotherapeutic regimens to control systemic metastases, and 3) previous trials of chemotherapy employed agents other than those known to be most effective against the primary malignancy. Furthermore, laboratory studies have demonstrated that cytotoxic levels of many drugs can be measured in tumor tissue from primary and metastatic brain tumors. These clinical and pharmacologic observations suggest that chemotherapy would be expected to have limited value unless known effective combination regimens are employed as first-line therapy in chemosensitive malignancies. Recent reports of chemotherapy for patients with brain metastases from small cell lung carcinoma, gestational choriocarcinoma, germ cell malignancies, and breast carcinoma do describe response rates in the brain similar to those in other organ sites. In conclusion, chemotherapy for cerebral metastases can be expected to be effective only when effective drugs for systemic metastases are available. While the blood-brain barrier may be an additional detriment to successful treatment, other factors may be more important.

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.

Advanced ovarian dysgerminoma with cure of tumor persistent in meninges

Isolated meningeal recurrence of ovarian cancer is uncommon. It is generally assumed that such cases are not accompanied by prolonged survival. We report the cure of a patient with advanced ovarian dysgerminoma who developed febrile carcinomatous meningitis 2 weeks after receiving her fifth course of combination chemotherapy (5 months after initiation of chemotherapy). No parenchymal brain disease was identified. The persistence of disease in the leptomeninges is related to the ability of the blood-brain barrier to exclude chemotherapeutic agents. The patient responded to craniospinal radiation and remains free of disease 2 years after completion of treatment.

Human central nervous system and plasma pharmacology of mitoxantrone

Mitoxantrone 5-6 mg/m2 was administered IV to 10 consenting patients prior to surgical resection of an intracerebral tumor. Plasma pharmacokinetic parameters were calculated and concentration of mitoxantrone in intracerebral tumors was determined. Concentrations of mitoxantrone were also determined in autopsy tissues of one of the patients who expired 192 days after receiving the drug. The plasma pharmacokinetics were best described by a 3 compartment model, with a tl/2 gamma of 4.74 +/- 5.53 h. Mitoxantrone concentrations in the intracerebral tumors were potentially cytotoxic and ranged from 4 to 322 ng/g. In all but one case, mitoxantrone concentration was higher in tumor than in concurrent plasma samples. There was no obvious relation between tumor mitoxantrone concentration and peak plasma mitoxantrone concentration or time from mitoxantrone administration to tumor removal. Low grade gliomas and viable tumors tended to have lower mitoxantrone concentrations than did other tumor types and necrotic tumors. In the patient undergoing autopsy, highest mitoxantrone concentrations were found in liver, thyroid and heart.

Combined intraommaya methotrexate, cytosine arabinoside, hydrocortisone and thio-TEPA for meningeal involvement by malignancies

Twenty-three adult patients with meningeal involvement by a variety of malignancies were treated with the intra-Ommaya combination of methotrexate, hydrocortisone, cytosine arabinoside, and thio-TEPA. Whole brain irradiation was also administered to most patients who had not previously received it. Most patients demonstrated improvement of cerebrospinal fluid parameters, but only 50% of the patients experienced neurological improvement. Patients who did not receive cranial irradiation and performance status 4 patients were less likely to respond than were patients who did receive cranial irradiation as part of their treatment and patients who were performance status 0-3. Four patients developed possible and 2 patients developed probable or definite serious neurological complications. Another 4 patients developed less severe, reversible neurological toxicity. It is possible (but still uncertain) that this regimen is more toxic than other less intensive regimens, and further studies should be undertaken cautiously.

Central nervous system pharmacology of Baker's antifolate (NSC139105) in man

Radiolabelled Baker's Antifolate (BAF) was administered to 6 patients undergoing surgical resection of intracerebral tumors. Levels of radioactivity in resected tumor and edematous brain adjacent to tumor were generally higher than levels in concurrent plasma samples and were generally comparable to levels in temporalis muscle. Levels in tumor cyst fluid were far lower than concurrent plasma levels and levels in surrounding tumor. Chromatography was performed on tumor from 2 patients and revealed that only a small proportion of the radioactivity represented unchanged BAF. The major metabolite present in tissues was 1 000 times less potent as an inhibitor of dihydrofolate reductase than was BAF. Five patients had cerebrospinal fluid (CSF) sampled following administration of tracer doses of radiolabelled BAF. Radioactivity levels were far lower in CSF than in plasma. Levels of radioactivity in the CSF were also far lower than levels in tumor and brain samples from other patients and were slightly lower than tumor cyst fluid levels. Two patients had CSF collected after they received therapeutic doses of BAF. In these patients, both CSF and plasma were assayed using a dihydrofolate reductase inhibition assay. As with tracer dose studies, CSF concentrations of BAF were substantially lower than were concurrent plasma concentrations. Thus it appears that only very low concentrations of BAF are attainable in human CSF and intracerebral tumor, although a metabolite which is a very weak inhibitor of dihydrofolate reductase attains high concentrations in tumor.

Penetration of teniposide (VM-26) into human intracerebral tumors. Preliminary observations on the effect of tumor type, rate of drug infusion and prior treatment with amphotericin B or oral glycerol

Thirty-four consenting patients received VM-26 50-100 mg/m2 I.V. before surgical resection of intracerebral tumor, and drug was measured using a high pressure liquid chromatographic technique. Sufficient tumor for analysis was obtained from 29 patients. Brain metastases (13 patients) had higher concentrations of VM-26 than did gliomas (13 patients). Concentrations were comparable in brain metastases and meningiomas (3 patients). Prolonged (24 h) infusion of VM-26 did not appear to result in higher tumor drug concentrations in 5 patients than did rapid (1 h) infusion in 24 patients. Pretreatment with Amphotericin-B 10 mg/m2 12 h and 1 h before VM-26 did not appear to have any effect on VM-26 uptake into 4 intracerebral tumors, although data were limited, and VM-26 concentrations were very high in 1 metastasis. Pretreatment with oral glycerol 500 mg/kg 18 h, 12 h, 6 h, and immediately before I.V. VM-26 may have resulted in increased penetration of VM-26 into 9 tumors, although confirmation is required. Amphotericin-B, glycerol, and operative conditions did not appear to alter VM-26 plasma pharmacokinetics.

Penetration of VP-16 (etoposide) into human intracerebral and extracerebral tumors

VP-16 100 mg/m2 was given intravenously to 10 patients undergoing surgical resection of intracerebral tumors, and the drug was assayed in resected tumor using high pressure liquid chromatography. VP-16 concentrations varied from undetectable (less than .1 microgram/g) to 5.9 micrograms/g (mean, 1.4 microgram/g). VP-16 concentrations in tumors were lower than concurrent plasma concentrations. In addition, intracerebral tumors had a lower concentration of VP-16 than did extracerebral tumors (mean VP-16 concentration, 3.9 micrograms/g) from 7 patients receiving VP-16 50-100 mg/m2 intravenously. Plasma pharmacokinetics of VP-16 were different in our patients with intracerebral tumors than in previously studied patients with extracerebral tumors and it is unclear what role this may played in variability of tumor VP-16 concentrations. VP-16 concentrations were similar in glioblastomas and brain metastases. Specimens from patients with small cell undifferentiated carcinoma of the lung had the highest VP-16 concentrations. A patient who had both viable and necrotic tumor resected during an occipital lobectomy had a higher drug concentration in the necrotic than in the viable area of tumor. In addition, VP-16 concentration decreased as a function of distance into brain from the tumor. Based on our data, VP-16 might be expected to have less activity against intracerebral than against extracerebral human tumors.

Cisplatin plus cytosine arabinoside in adults with malignant gliomas

A combination of cisplatin and cytosine arabinoside was used to treat 21 patients with glioblastomas and 5 patients with recurrent grade II gliomas. Cisplatin 60-100 mg/m2 was given I.V. in 250 ml 0.45% saline and preceded by 500 ml dextrose 5% in 0.45% saline. Mannitol 50 g was given I.V. concurrently with the cisplatin. Cytosine arabinoside 500-1000 mg/m2 was given by rapid I.V. infusion immediately after the cisplatin. Of 25 evaluable patients, 10 (40%) experienced objective tumor shrinkage on CT scan, and 6 (24%) stabilized. There were 2 complete remissions. Patients who had had no prior treatment had a higher response rate (58%) than those previously treated (23%). Myelosuppression occurred in some patients 2-3 weeks after treatment. Gastrointestinal toxicity (vomiting and diarrhea) was dose-limiting. Two patients had possible neurological toxicity. Recommended doses for further studies are cisplatin 90 mg/m2 and cytosine arabinoside 900 mg/m2.