Hemorrhagic encephalitis produced by selective non-occlusive intracarotid BCNU injection in dogs

Cerebral injury from intracarotid injection in an alpaca (Vicugna pacos)

A mixture of ketamine, xylazine, and butorphanol was inadvertently injected into the right carotid artery of a 1-year-old alpaca. Injection was followed by a brief period of recumbency and seizure activity. The alpaca recovered, but was euthanatized 72 hr later because of development of progressive neurologic deficits. Pathologic findings were confined to the right cerebrum, meninges, thalamus, and hippocampus. Cerebrocortical edema with astrocytic reaction, perivascular hemorrhage and neutrophilic infiltration, and fibrinoid necrosis of vasculature within the meninges and thalamus were the most prominent lesions. Neuronal necrosis was mild. Astrocytic reaction within the right cerebral cortex was confirmed with immunohistochemistry for glial fibrillary acidic protein.

Intracarotid delivery of drugs: the potential and the pitfalls

The major efforts to selectively deliver drugs to the brain in the past decade have relied on smart molecular techniques to penetrate the blood-brain barrier, whereas intraarterial drug delivery has drawn relatively little attention. Meanwhile, rapid progress has been made in the field of endovascular surgery. Modern endovascular procedures can permit highly targeted drug delivery by the intracarotid route. Intracarotid drug delivery can be the primary route of drug delivery or it could be used to facilitate the delivery of smart neuropharmaceuticals. There have been few attempts to systematically understand the kinetics of intracarotid drugs. Anecdotal data suggest that intracarotid drug delivery is effective in the treatment of cerebral vasospasm, thromboembolic strokes, and neoplasms. Neuroanesthesiologists are frequently involved in the care of such high-risk patients. Therefore, it is necessary to understand the applications of intracarotid drug delivery and the unusual kinetics of intracarotid drugs.

Targeting the brain: rationalizing the novel methods of drug delivery to the central nervous system

Drug delivery to the brain has remained one of the most vexing problems in translational neuroscience research. This review rationalizes the strategies to target drugs to the brain. Factors such as the speed of intervention, the scale of intervention, the state of BBB, and the permissible risks, will all be critical in deciding how best to deliver drugs to a target site in the brain for a specific clinical situation.

DTI-015 produces cures in T9 gliosarcoma

DTI-015 (BCNU in 100% ethanol) utilizes solvent-facilitated perfusion for the intratumoral treatment of gliomas. The water-miscible organic solvent vehicle, ethanol, facilitates a rapid and thorough saturation of the'tumor with the dissolved anticancer agent, BCNU. Rats bearing established intracranial T9 gliosarcoma tumors received no treatment (group 1), a single intratumoral injection of ethanol vehicle (group 2) or DTI-015 (5 mg/kg BCNU) (group 3), or a single intratumoral injection of DTI-015 followed by systemic BCNU (group 4). Ethanol alone (n=13) had no effect on survival; MST=17 days compared to 18 days for untreated controls (n=35). DTI-015 (n=45) produced an ILS of 417% (MST=93) and 472% (MST=103) when combined with systemic BCNU (n=14). Overall, 24 of 59 rats receiving DTI-015 were judged to be cured, with 20 living a normal life span of 600 to 700 days, and 4 rats sacrificed healthy at 121, 135, 307, and 384 days post DTI-015 with no evidence of viable T9 tumor. Histology demonstrated that DTI-015 totally eradicated the T9 tumors in animals living a normal life span. The results demonstrate that a single injection of DTI-015 produces a 40% cure rate in rats bearing established intracranial T9 tumors.

In vivo measurement of tumor blood oxygenation by near-infrared spectroscopy: immediate effects of pentobarbital overdose or carmustine treatment

Near-infrared (NIR) spectroscopy was used to measure blood oxygen saturation (SO2) in vivo, in normal rat brain and in subcutaneously-implanted rat 9L gliosarcoma. Changes in cranial and tumor blood SO2 were measured during lethal pentobarbital overdose. After sacrifice, SO2 of cranial blood fell rapidly to a mean of 5.0% of the pre-sacrifice values, whereas SO2 of tumor blood stabilized at a mean of 72.4% of the pre-sacrifice values. This suggests that oxygen consumption by tumor is very low compared to brain. Cranial blood had a higher SO2 than tumor blood before sacrifice (p = 0.03), and a lower SO2 after sacrifice (p = 0.02). The magnitude of the change in SO2 after sacrifice was greater in normal brain than in tumor (p = 0.02), showing that brain tissue uses a greater proportion of the oxygen in ischemic blood than does tumor tissue. To determine the effect of carmustine (BCNU) treatment on tumor and cranial blood SO2, we compared BCNU-treated rats with sham-treated rats. Continuous NIR measurements before and immediately following treatment (ie. over 30-60 min) showed that tumor blood SO2 tended to increase after BCNU treatment, whereas SO2 tended to decrease following sham-treatment. The difference in SO2 between treated and control tumors was significant at 60 min (p = 0.02). Thus BCNU treatment can potentially result in immediate increases in tumor oxygenation. The increase in treated tumor blood SO2 occurred despite the fact that there was no change in cranial blood SO2 even at day 4 following treatment. Tumor blood SO2 was inversely correlated with tumor size (p = 0.001), confirming that blood is more poorly oxygenated in large tumors.

Delivery of a novel nitrosourea, MCNU, to the brain tissue in glioma-bearing rats. Intracarotid versus intravenous infusion

We observed the tissue delivery of a novel water-soluble nitrosourea, 1-(2-chloroethyl)-3-(methyl-alpha-D-glucopyranos-6-yl)-1-nitros our ea (MCNU) in rats bearing experimental brain tumors by conducting autoradiography on all. Prior to this study, the development of a streaming phenomenon was ascertained (and thus finding the optimum velocity for intra-arterial infusion) by 14C-iodoantipyrine (IAP) autoradiography. Furthermore, a single pass extraction value of MCNU was measured. At an arterial infusion rate of 0.2 ml/min., the streaming phenomenon was recognized but the tracer was fairly evenly distributed at a rate of 1.0 ml/min. On the other hand, the single pass extraction value for MCNU was 0.18 +/- 0.036 (mean +/- S.D., n = 3, under pentobarbital anesthesia). It was suggested that MCNU is very unlikely to be transported into the normal rat brain. We conducted 14C-MCNU autoradiography to observe tissue distribution of MCNU following its intra-arterial and intravenous infusions in a brain tumor model using rats. The normal side (the side where no infusions were given) and the cerebral cortex at the side affected by the tumor (the side where the infusion was given) showed hardly any uptake of 14C-MCNU in both the intra-arterial and intravenous infusion groups. The tumorous section was divided into the periphery and the center to measure tissue concentration of the tracer in each section. Compared against the cortical section, the periphery and the center showed significant increases in the concentration (approximately 11 to 15 times and 3 to 7 times, respectively, the figure for the cortical region) for both the intra-arterial and intravenous groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatal necrotizing encephalopathy complicating treatment of malignant gliomas with intra-arterial BCNU and irradiation: a pathological study

We describe the neuropathologic findings at autopsy in six patients who developed a progressive encephalopathy complicating the treatment of malignant gliomas with combined intra-arterial 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and cerebral irradiation. Four brains were free of tumor and one contained a microscopic focus of residual glioma. In only one case was there evidence of tumor progression. A disseminated process characterized by miliary foci of necrosis with mineralizing axonopathy was present in all cases, restricted to the internal carotid distribution of the perfused hemisphere and involving primarily though not exclusively the white matter, which was diffusely and severely edematous. This was combined in 3 cases with a histologically dissimilar, massive necrotizing leukoencephalopathy indistinguishable from pure radionecrosis. Much of the toxicity of this therapy is mediated by vascular injury, but the disseminated necrotizing lesion probably reflects, at least in part, direct neural damage.

Pathology of high-dose intraarterial BCNU

Current radiotherapy and chemotherapy for high-grade and/or recurrent astrocytomas result in only moderate increases in survival time. In an attempt to improve this, high-dose intraarterial 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) was utilized on 41 patients with these neoplasms over a 4-year period at our institution. Eight of the 41 patients came to biopsy or autopsy at times sufficiently following intraarterial BCNU infusion and with adequate tissue samples to evaluate the histological changes induced by the drug. Two of the eight patients received no additional radiotherapy or chemotherapy. The other five received conventional whole brain irradiation, and one additionally received 50 mg of intravenous 2-deoxy-5-fluorouridine (FUdR). The eight patients showed mild to severe amounts of bland coagulative necrosis, vascular hyalinization, perithelial fibroblastic proliferation, and endothelial atypia. One of these patients had a recognized severe clinical leukoencephalopathy, and the pathological changes were maximal in this individual. Six patients had radiological evidence of increased necrosis and clinical deterioration prebiopsy or preautopsy, but, within this group, there were no distinguishing clinical features. Microscopic changes were severe in two of these patients. A final patient died of unrelated septic shock 5 days after a single infusion of intraarterial BCNU, and the microscopic changes were least extensive in her. This study suggests that high-dose intraarterial BCNU can cause a leukoencephalopathy, sometimes severe, either alone or in synergistic fashion with cranial irradiation. Occurrence of such leukoencephalopathy is not always predictable based on BCNU dosage and cannot always be reliably distinguished from tumor regrowth or tumor necrosis by radiological and clinical evaluation. Hence, caution most be exercised in continuation of high-dose intraarterial BCNU protocols.

Carotid artery mixing with diastole-phased pulsed drug infusion

Focal injury to the brain or retina is a frequent complication of drug delivery to the internal carotid artery (ICA) and may be due to poor mixing of the drug with blood at the infusion site. Rhesus monkeys were studied to determine whether phased drug delivery during diastole from a modified pulsatile angiographic injector would improve drug mixing in vivo. A radiolabeled flow tracer, carbon-14-iodoantipyrine (14C-IAP), was injected into the ICA of three monkeys in 80-msec pulses, each ending at least 50 msec before the end of local diastole. Local isotope concentration in the brain was determined by quantitative autoradiography. The ratio of highest to lowest concentration was 1.86 +/- 0.26 (mean +/- standard deviation) in the frontoparietal cortex, 1.65 +/- 0.42 in the frontoparietal white matter, 1.89 +/- 0.28 in the temporal cortex, and 1.39 +/- 0.17 in the basal ganglia. These results were similar to recordings in three control animals that received intravenous 14C-IAP to demonstrate complete drug mixing (1.37 +/- 0.12, 1.41 +/- 0.11, 1.70 +/- 0.08, 1.22 +/- 0.24, respectively), and contrasted to findings in five animals which received continuous intracarotid infusions to demonstrate standard ICA drug delivery (4.54 +/- 2.07, 2.94 +/- 1.45, 5.43 +/- 3.57, 3.60 +/- 2.90, respectively). Pulsed intra-arterial infusion during diastole provides a technically simple method for improving intravascular drug mixing, and results in drug delivery to tissue capillaries that is proportional to blood flow.

Sudden onset of blindness in patients treated with oral CCNU and low-dose cranial irradiation

Three patients developed the sudden onset of total blindness several months after treatment with oral CCNU and low-dose whole-brain radiation. The anterior visual system was included in the radiation field in all patients. Radiotherapy was given for a frontal-lobe glioblastoma multiforme, for central nervous system prophylaxis in a patient with oat cell carcinoma of the lung, and for a parietal-lobe glioblastoma multiforme. None of the neoplasms involved the anterior visual system. The radiation dose ranged from 3000 to 4650 rad and the oral CCNU dosage from 300 mg to 1050 mg. Patients 1 and 2 also received other chemotherapeutic agents. Patient 3 who was treated only with oral CCNU and cranial irradiation died. At autopsy the brain showed a widely infiltrating residual high-grade glioma as well as patchy coagulative necrosis with swollen axons and dystrophic calcifications. The optic chiasm showed severe demyelination, axonal loss, and hyalinized vessels. Synergism between oral CCNU and radiation may account for the blindness produced.

Central neurotoxicity following intracarotid BCNU chemotherapy for malignant gliomas

Central neurotoxicity is reported in 5 of 16 patients with recently diagnosed anaplastic gliomas, who received intra-arterial BCNU (200 mg/M2/course) and also 2 in a series of 26 patients with recurrent gliomas similarly treated. Neurotoxicity was usually delayed, commencing several weeks following the second or third course. CT scans during central neurotoxicity represented 1 or more of 3 patterns: no change; increased low density area(s); and/or ipsilateral gyral enhancement and punctate calcification in the middle cerebral artery territory. In one clinicopathological correlation, coagulative necrosis of the white matter was observed, identical histologically to those changes recognized as delayed vascular events following radiotherapy. Cautious exploration of the various clinical factors that may contribute to this toxicity seems appropriate, as exploration of the potential benefits of regional chemotherapeutic infusions is undertaken.

Interspecies scaling of regional drug delivery

Calculation of the pharmacokinetic advantage of regional drug administration requires knowledge of the relevant intercompartment transport parameter. In a lumped model this is the blood (or plasma) flow rate for intra-arterial drug infusion or the permeability-area product for intraperitoneal or intrathecal administration. It is suggested that the perfusion of many tissues and the intrinsic permeability of the peritoneal surface or the brain-cerebrospinal fluid interface are similar among mammals. This provides a clear allometric basis for interspecies scaling based on organ size or surface areas. Intra-arterial or intrathecal treatment of the brain or meninges is a particularly interesting problem because of the relatively large brain of humans and because increased folding results in a cortical surface area that is almost proportional to brain size. Major unresolved issues remain concerning the distributed character of the processes such as streaming of drug infused into an artery and nonuniform mixing of cerebrospinal fluid.

Effect of difluoromethylornithine on the antiglioma therapeutic efficacy of intra-arterial BCNU

In an attempt to improve glioma management, an animal model was developed to evaluate the therapeutic efficacy of intra-arterial 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Furthermore, the model was used to study the antitumor activity of D,L-alpha-difluoromethylornithine (DFMO), a polyamine-biosynthesis inhibitor, used both as a single agent and in combination with intra-arterial BCNU. An N-methylnitrosourea-induced gliosarcoma (T9) was transplanted stereotaxically into the right caudate nucleus of male Fischer 344 rats. Animals receiving a single low-dose (5 mg/kg) intracarotid injection of BCNU 9 days following tumor implantation had a 57% increase in life span compared with untreated control rats (p less than 0.001). Intracarotid drug delivery was more effective than systemic (intraperitoneal) administration of the same dose of BCNU. When given as a single agent, DFMO demonstrated dose-dependent effectiveness. As part of a combined regimen, DFMO enhanced the antitumor therapeutic activity of both systemic (intraperitoneal) and intra-arterial BCNU. Survival times of animals receiving combined DFMO and intra-arterial BCNU were almost double those of untreated controls, and were significantly better than survival times of animals receiving combined DFMO and intraperitoneal BCNU. These findings suggest methods to optimize current clinical chemotherapy for glioma.

Intracarotid BCNU leukoencephalopathy

Intracarotid 1,3-bis(2-chloroethyl)-1-nitrosurea (BCNU) is now a frequently used chemotherapeutic agent for high-grade glial neoplasms. The toxicity from such therapy has not been well-documented. A 50-year-old man with a left frontoparietal grade 4 astrocytoma received three injections of intracarotid BCNU, 400 mg each, over a 2-month period. No radiation or other chemotherapy was ever given. He tolerated the BCNU injections well, with some reduction of tumor bulk, until the third dose. After his last injection, his condition gradually deteriorated; he became obtunded, and died 5 weeks later. At autopsy, the brain showed extensive cavitation and coagulative necrosis, fibrinoid vascular necrosis, edema, swollen axons, and bizarre cellular morphologic features confined to the BCNU perfusion territory. Grade 4 astrocytoma remained in the right hemisphere and in the left occipital lobe, sites outside the area of BCNU perfusion. Intracarotid BCNU can result in a severe leukoencephalopathy similar to that seen with methotrexate or delayed radionecrosis.

Drug streaming during intra-arterial chemotherapy

Treatment of brain tumors by intra-arterial (IA) chemotherapy is occasionally complicated by sites of focal toxicity in the brain and retina. A possible cause of focal toxicity is non-uniform drug delivery due to intravascular drug streaming. To investigate this phenomenon in vivo, the authors examined the distribution of drug delivery after internal carotid artery (ICA) infusion in rhesus monkeys. Carbon-14 (14C)-labeled iodoantipyrine was delivered into the ICA of eight monkeys at slow infusion rates (1% to 2% of ICA flow) or at fast infusion rates (20% of ICA flow) combined with additional techniques to promote mixing with ICA blood. Two monkeys received intravenous (IV) 14C-antipyrine. Uniformity of delivery was assessed by comparing high-to-low ratios of isotope concentration in four brain regions evaluated by quantitative autoradiography. There was striking non-uniformity of drug delivery in the slow IA infusion group, with as much as 13-fold differences in drug concentration in anatomically contiguous areas. The values of high-to-low concentration ratios (mean +/- standard deviation) in individual autoradiographic planes were: 1) frontoparietal cortex: slow IA infusion 4.54 +/- 2.07, fast IA infusion 1.71 +/- 0.31, IV infusion 1.30 +/- 0.174; 2) frontoparietal white matter: slow IA infusion 2.94 +/- 1.45, fast IA infusion 1.59 +/- 0.41, IV infusion 1.34 +/- 0.21; 3) temporal cortex: slow IA infusion 5.43 +/- 3.57, fast IA infusion 1.69 +/- 0.24, IV infusion 1.67 +/- 0.25; 4) basal ganglia: slow IA infusion 3.6 +/- 2.9, fast IA infusion 1.18 +/- 0.10, IV infusion 1.09 +/- 0.04. Differences between concentration ratios after slow IA and fast IA infusion are significant (p less than 0.01); those between fast IA and IV infusion are not significant. Intra-arterial drug administration at infusion rates analogous to those currently used clinically results in drug streaming with markedly heterogeneous drug deposition in the perfused hemisphere. This may cause suboptimal drug levels in the tumor, and toxic levels at sites within the perfused hemisphere. This effect can be abrogated by techniques that eliminate drug streaming.

Comparison of various methods for delivering radiolabeled monoclonal antibody to normal rat brain

Different methods were evaluated for delivering iodine-125 monoclonal antibodies (Mab's) to the central nervous system in 40- to 99-gm Fischer rats. By evaluating interhemispheric, interregional, and brain:blood ratios of Mab's, the efficacy of intracarotid (IC) or intravenous (IV) administration of Mab's with and without prior IC perfusion with 0.9% NaCl (normal saline, NS), 1.4 M mannitol, or 1.6 M arabinose, or of femoral artery perfusion with 1.4 M mannitol was evaluated. No difference was seen between IC and IV administration of Mab's with or without prior perfusion. Intracarotid perfusion with hyperosmolar agents was required to disrupt the blood-brain barrier (BBB) and to significantly elevate brain levels of Mab's. The brain and blood levels of Mab's were elevated in all regions of the brain following hyperosmolar BBB disruption. However, the levels were significantly higher in the ipsilateral hemisphere, with cross-over occurring primarily in the vascular distribution of the contralateral anterior cerebral artery. Intracarotid hyperosmolar perfusion produced 450% to 500% increases in ipsilateral and 240% to 280% increases in contralateral hemispheric brain:blood Mab ratio levels compared to those achieved with NS perfusion. For IC perfusion of mannitol or arabinose, flow rates ranging from 0.017 to 0.052 ml/sec were equally effective in disrupting the BBB. Insignificant morbidity and mortality rates were noted up to 2 weeks following BBB disruption. Additional ligation of major extracranial branches of the external and internal carotid arteries prior to IC perfusion did not result in a selective increase in hemispheric Mab levels. Temporally, following hyperosmolar BBB disruption, brain:blood Mab ratios remained elevated bilaterally at 7 days after Mab delivery, with the ipsilateral hemispheric levels remaining significantly elevated compared with the contralateral hemispheric levels until Day 5, when the ratio returned to the nonperfused range. Catheterization was required in the small animals and was performed under magnification in 10 to 20 minutes, with less than an 8% overall morbidity and mortality. The methodology developed should prove helpful in delivery of Mab's or other agents in rat tumor models and experimental models for other disease entities.

Intra-arterial BCNU chemotherapy for treatment of malignant gliomas of the central nervous system

Because of the rapid systemic clearance of BCNU (1,3-bis-(2-chloroethyl)-1-nitrosourea), intra-arterial administration should provide a substantial advantage over intravenous administration for the treatment of malignant gliomas. Thirty-six patients were treated with BCNU every 6 to 8 weeks, either by transfemoral catheterization of the internal carotid or vertebral artery or through a fully implantable intracarotid drug delivery system, beginning with a dose of 200 mg/sq m body surface area. Twelve patients with Grade III or IV astrocytomas were treated after partial resection of the tumor without prior radiation therapy. After two to seven cycles of chemotherapy, nine patients showed a decrease in tumor size and surrounding edema on contrast-enhanced computerized tomography scans. In the nine responders, median duration of chemotherapy response from the time of operation was 25 weeks (range 12 to more than 91 weeks). The median duration of survival in the 12 patients was 54 weeks (range 21 to more than 156 weeks), with an 18-month survival rate of 42%. Twenty-four patients with recurrent Grade I to IV astrocytomas, whose resection and irradiation therapy had failed, received two to eight courses of intra-arterial BCNU therapy. Seventeen of these had a response or were stable for a median of 20 weeks (range 6 to more than 66 weeks). The catheterization procedure is safe, with no immediate complication in 111 infusions of BCNU. A delayed complication in nine patients has been unilateral loss of vision secondary to a retinal vasculitis. The frequency of visual loss decreased after the concentration of the ethanol diluent was lowered.

BCNU solubility and toxicity in the treatment of malignant astrocytomas

Administration of BCNU into the carotid artery as treatment for malignant astrocytomas has produced retinal and brain toxicity. It is unclear whether the BCNU diluent, ethanol, is the cause of the toxicity, but the elimination of the ethanol is an attractive possibility. Clinically, decreasing the ethanol from 2.0 ml/100 mg BCNU to 0.75 ml/100 mg BCNU resulted in a marked decrease in eye toxicity. To simulate this clinical situation, three 500-mg solutions of BCNU, ethanol, and saline were prepared, decreasing the ethanol concentration from 3.0 ml to 2.0 ml to 0.75 ml/100 mg BCNU. The amount of BCNU recovered in vitro after simulated clinical administration of the three solutions decreased from 84.9% to 38.3% as the diluent decreased. Therefore, drug delivery at a fixed BCNU dose will decrease with the amount of ethanol diluent used. The clinical decrease in eye toxicity must be partly attributed to a decrease in the amount of BCNU delivered to the retina. Simulated administration of a solution of 500 mg BCNU/150 ml of 5% dextrose in water (D5W) gave 83.7% BCNU recovery. The D5W gives solubility comparable to that provided by 3.0 ml ethanol to each 100 mg BCNU, and its use eliminates ethanol as a potential retinal and brain toxin.

Neurotoxicity of chemotherapeutic agents after blood-brain barrier modification: neuropathological studies

We examined in 47 dogs the effects of 5-fluorouracil, Adriamycin (doxorubicin hydrochloride), cis-platinum (cis-diamminedichloroplatinum) cyclophosphamide, and bleomycin given in association with osmotic blood-brain barrier modification. The dose of drug ranged from 100% to as little as 5 to 10% of the conventional systemic dosage. Serial neurological observation and subsequent postmortem neuropathological evaluation at times varying from 2.5 hours to 52 days after drug administration showed that cis-platinum and Adriamycin were highly neurotoxic, as evidenced by neurological deficits and pathological changes in the central nervous system parenchyma; 5-fluorouracil and bleomycin had much less, but consequential neurotoxicity; and cyclophosphamide was not associated with substantial toxicity. Intracarotid cis-platinum, unlike the other drugs, damaged the blood-brain barrier and resulted in marked neurotoxicity in the absence of osmotic blood-brain barrier opening. The neural lesions produced by these agents were not specific but were manifested as foci of hemorrhagic necrosis and edema. In addition, secondary brainstem hemorrhage was observed in animals that developed transtentorial herniation. On the basis of these studies, of five drugs studied at a wide range of doses, only cyclophosphamide appears to be safe enough to evaluate in clinical trials that utilize blood-brain barrier modification to enhance drug delivery. These studies also suggest that the lack of neurotoxicity associated with the usual administration of most chemotherapeutic agents probably stems from limited entry of drug into the brain through an intact blood-brain barrier.