Tumor regression with regional distribution of the targeted toxin TF-CRM107 in patients with malignant brain tumors.

We investigated regional therapy of recurrent malignant brain tumors with transferrin-CRM107, a conjugate of human transferrin (Tf) and a genetic mutant of diphtheria toxin (CRM107) that lacks native toxin binding. Physiological barriers to delivering proteins to tumor and surrounding infiltrated brain were circumvented with high-flow interstitial microinfusion. At least a 50% reduction in tumor volume on magnetic resonance imaging (MRI) occurred in 9 of 15 patients who could be evaluated (60%), including two complete responses. Peritumoral toxicity developed 1-4 weeks after treatment in three of three patients at 1.0 microg/ml, but in zero of nine patients treated at lower concentrations. No symptomatic systemic toxicity occurred. Regional perfusion with Tf-CRM107 produces tumor responses without systemic toxicity in patients with malignant brain tumors refractory to conventional therapy. Direct interstitial infusion can be used successfully to distribute a large protein in the tumor and infiltrated brain surrounding the tumor.

Intraventricular immunotoxin therapy for leptomeningeal neoplasia.

OBJECTIVE: The goals of this clinical trial of intraventricular 454A12-rRA therapy were to identify dose-limiting toxicities, to evaluate the pharmacokinetics of single-dose intraventricular 454A12-rRA, and to detect antitumor activity. METHODS: We performed a pilot study of intraventricular therapy with the immunotoxin 454A12-rRA in eight patients with leptomeningeal spread of systemic neoplasia. The immunotoxin 454A12-rRA is a conjugate of a monoclonal antibody against the human transferrin receptor and recombinant ricin A chain, the enzymatically active subunit of the protein toxin ricin. Patients were treated with single doses of 454A12-rRA ranging from 1.2 to 1200 micrograms. RESULTS: The early phase half-life of 454A12-rRA in ventricular cerebrospinal fluid (CSF) averaged 44 +/- 21 minutes, and the late phase half-life averaged 237 +/- 86 minutes. The clearance of the immunotoxin was faster than the clearance of coinjected technetium-99m-diethylenetriamine penta-acetic acid, averaging approximately 2.4-fold greater. No 454A12-rRA degradation was detected by Western blot analysis of ventricular CSF for a period of 24 hours, and bioactivity was retained in CSF paralleling the concentration of immunotoxin. No acute or chronic drug toxicity was identified in patients who received less than or equal to 38 micrograms of 454A12-rRA by intraventricular injection. Doses more than or equal to 120 micrograms caused a CSF inflammatory response that was associated with transient headache, vomiting, and altered mental status. This acute syndrome was responsive to steroids and CSF drainage. No systemic toxicity was detected. In four of the eight patients, a greater than 50% reduction of tumor cell counts in the lumbar CSF occurred within 5 to 7 days after the intraventricular dose of 454A12-rRA; however, no patient had their CSF cleared of tumor, and clinical or magnetic resonance imaging evidence of tumor progression was demonstrated in seven of the eight patients after treatment. CONCLUSION: Tumoricidal concentrations of the immunotoxin 454A12-rRA can be attained safely in the CSF of patients with leptomeningeal tumor spread.

Efficacy of direct intratumoral therapy with targeted protein toxins for solid human gliomas in nude mice.

Targeted protein toxins are a new class of reagents with the potential for great tumor selectivity and cytotoxic potency. Two such compounds were studied: 1) Tf-CRM107, a conjugate of human transferrin (Tf) and diphtheria toxin with a point mutation (CRM107); and 2) 454A12-rRA, a conjugate of a monoclonal antibody (454A12) to the human Tf receptor and recombinant ricin A chain (rRA). Both compounds are potent and specific in killing human glioblastoma cell lines in vitro. The authors investigated the activity of these reagents administered intratumorally against solid U251 MG human gliomas in vivo. Nude mice with established U251 MG flank tumors (0.5 to 1.0 cm in diameter) were randomly assigned to be treated with 100-microliters intratumoral injections of Tf-CRM107 (10 micrograms) or 454A12-rRA (10 micrograms), equimolar doses of CRM107 (4.3 micrograms), 454A12 antibody (7.5 micrograms), or rRA (1.5 micrograms), or phosphate-buffered saline (PBS) every 2 days for a total of four doses. Tumor volume and animal weight were assessed by a blinded observer before each treatment and biweekly for 30 days after initiating therapy. With Tf-CRM107 administration, tumor regression of greater than 95% occurred by Day 14 (p < 0.01) and tumors did not recur by Day 30. Treatment with 454A12-rRA caused a 30% decrease in tumor volume by Day 14 (p < 0.01). Treatment with equimolar doses of the unconjugated targeted protein toxin components CRM107, 454A12, or rRA caused significant U251 MG tumor growth inhibition, but the effects were less potent than the antitumor effects of the conjugates. This study also characterized the dose-response effect of Tf-CRM107 on tumor growth and tumor weight on Day 30. Nude mice with established U251 MG flank tumors (0.5 to 1.0 cm in diameter) were treated with 100-microliters intratumoral injections of 10, 1.0, or 0.1 microgram of Tf-CRM107 or PBS every 2 days for a total of four doses. All three doses of Tf-CRM107 significantly inhibited tumor growth by Day 14 (p < 0.01) and at Day 30 (p < 0.05), with a significant dose-response relationship. This study demonstrated in vivo efficacy of the targeted toxins Tf-CRM107 and 454A12-rRA against a human glioma. With intratumoral administration, the effect of Tf-CRM107 was tumor-specific and in some animals curative. Regional therapy with these potent tumor-specific agents using direct intratumoral infusion should limit systemic toxicity and may be efficacious against brain tumors.

Convection-enhanced distribution of large molecules in gray matter during interstitial drug infusion.

Many novel experimental therapeutic agents, such as neurotrophic factors, enzymes, biological modifiers, and genetic vectors, do not readily cross the blood-brain barrier. An effective strategy to deliver these compounds to the central nervous system is required for their application in vivo. Under normal physiological conditions, brain interstitial fluid moves by both bulk flow (convection) and diffusion. It has recently been shown that interstitial infusion into the white matter can be used to increase bulk flow, produce interstitial convection, and efficiently and homogeneously deliver drugs to large regions of brain without significant functional or structural damage. In theory, even more uniform distribution is likely in gray matter. In the current study, four experiments were performed to examine if convection-enhanced delivery could be used to achieve regional distribution of large molecules in gray matter. First, the volume and consistency of anatomical distribution of 20 microliters of phaseolus vulgaris-leukoagglutinin (PHA-L; molecular weight (MW) 126 kD) after continuous high-flow microinfusion into the striatum of five rats over 200 minutes were determined using immunocytochemistry and quantified with image analysis. Second, the concentration profile of 14C-albumin (MW 69 kD) infused under identical conditions was determined in four hemispheres using quantitative autoradiography. Third, the volume of distribution after convection-enhanced infusion of 250 or 500 microliters biotinylated dextran (b-dextran, MW 10 kD), delivered over 310 minutes into the caudate and putamen of a rhesus monkey from one (250 microliters) or two (500 microliters) cannulas, was determined using immunocytochemistry and quantified with image analysis. Finally, the ability to target all dopaminergic neurons of the nigrostriatal tract via perfusion of the striatum with subsequent retrograde transport was assessed in three experiments by immunohistochemical analysis of the mesencephalon following a 300-minute infusion of 27 microliters horseradish peroxidase-labeled wheat germ agglutinin (WGA-HRP) into the striatum. Convection-enhanced delivery reproducibly distributed the large-compound PHA-L throughout the rat striatum (the percent volume of the striatum perfused, Vs, was 86% +/- 5%; mean +/- standard deviation) and produced a homogeneous tissue concentration in the perfused region (concentration of 14C-albumin relative to infusate concentration 30% +/- 5%). In the monkey, the infusion widely distributed b-dextran within the striatum using one cannula (caudate and putamen Vs = 76% and 76%) or two cannulas (Vs = 90% and 71%).(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic interstitial infusion of protein to primate brain: determination of drug distribution and clearance with single-photon emission computerized tomography imaging.

High-flow interstitial infusion into the brain, which uses bulk fluid flow to achieve a relatively homogeneous drug distribution in the extracellular space of the brain, has the potential to perfuse large volumes of brain. The authors report reproducible long-term delivery of 111In-diethylenetriamine pentaacetic acid-apotransferrin (111In-DTPA-Tf) (molecular mass 81 kD) to Macaca mulatta brain and monitoring with single-photon emission computerized tomography (SPECT). The 111In-DTPA-Tf was infused at 1.9 microl/minute over 87 hours into the frontal portion of the centrum semiovale using a telemetry-controlled, fully implanted pump. On Days 1, 3, 4, 8, 11, and 15 after beginning the infusion, planar and SPECT scans of 111In-DTPA-Tf were obtained. Spread of protein in the brain ranged from 2 to 3 cm and infusion volumes ranged from 3.9 to 6.7 cm3. Perfusion of over one-third of the white matter of the infused hemisphere was achieved. From brain SPECT images of (99m)Tc-hexamethylpropyleneamine oxime, which was administered intravenously before each 111In scan, the authors also found that blood perfusion in the infused region was reduced by less than 5% relative to corresponding noninfused regions. Histological examination at 30 days revealed only mild gliosis limited to the area immediately surrounding the needle tract. These findings indicate that long-term interstitial brain infusion is effective for the delivery of drugs on a multicentimeter scale in the primate brain. The results also indicate that it should be possible to perfuse targeted regions of the brain for extended intervals to investigate the potential utility of neurotrophic factors, antitumor agents, and other materials for the treatment of central nervous system disorders.

Acute hyperthermia following stereotactic radiosurgery for pituitary adenoma.

A 71-year-old male presented with a large pituitary adenoma with superior extension into the optic chiasm and suprasellar cistern. He was treated with stereotactic radiosurgery to a dose of 16 Gy. Approximately 1 h after radiosurgery he developed fever; his temperature peaked at 105.1 degrees F and normalized about 20 h later. This case demonstrates that acute hyperthermia is a potential complication following high dose stereotactic radiosurgery for large pituitary tumours.

Biosynthesis of a D-glucosyl polyisoprenyl diphosphate in particulate preparations of Micrococcus lysodeikticus.

Particulate fractions of Micrococcus lysodeikticus incubated with UDP-D-[14C]glucose incorporated radioactivity into a chloroform - methanol-soluble, low-mol. wt. compound, and into a polymer. The low-mol. wt. compound consisted of a glucolipid that was extremely labile to mild acid hydrolysis with the formation of D-[14C]glucose, and to mild alkali, yielding 14C-labeled alpha-D-glucopyranose 1,2-phosphate and D-glucose 2-phosphate. The labeled glucolipid was eluted from a DEAE-cellulose column at a salt concentration higher than that required by synthetic ficaprenyl (D-glucopyranosyl phosphate), and it migrated more slowly than the latter compound in t.l.c. Formation of the glucolipid was stimulated by exogenous ficaprenyl phosphate, but not by C55-dolichyl phosphate. These results suggest that the [14C]glucolipid has the characteristic properties of a polyisoprenyl glucosyl diphosphate.

Reconstituted basement membrane (matrigel) enhances the growth of human glioma cell lines in nude mice.

Transplantation of human cancers into immunologically deficient mice is widely used to study potential therapeutic interventions in vivo. For brain tumor research, however, several factors limit more widespread application of this animal model. First, only a minority of human glioma-derived cell lines are tumorigenic in nude mice. In addition, even for tumorigenic cell lines, tumor take is variable and growth is often slow for tumors derived from cell inoculums. Reconstituted components of tumor basement membrane (matrigel) have been found to improve the growth in nude mice of several types of human tumors originating outside the central nervous system when premixed with the tumor cells before subcutaneous inoculation. We investigated the ability of matrigel to enhance the growth in nude mice of tumors derived from the human glioma cell lines U-251 MG, U-373 MG, SNB-78 and SNB-101. Athymic nude mice (NIH Swiss background, nu/nu genotype) were inoculated subcutaneously with 1.0 x 10(6) tumor cells alone or after premixing with an equal volume of liquid matrigel. U-251 and U-373 cells were tumorigenic, with palpable tumors present by about 2 to 3 weeks. Co-injection of these cell lines with matrigel resulted in higher tumor-take rates, from 6/10 to 8/8 animals for U-251 at 60 days, and from 9/12 to 11/11 animals for U-373 at 60 days. Matrigel also enhanced tumor growth, with tumors at 45 days significantly larger than those formed in the absence of matrigel, for both cell lines (p < 0.01). SNB-78 and SNB-101 cells did not give rise to progressively enlarging solid tumors with or without matrigel. Matrigel enhances the growth of tumorigenic human gliomas in athymic nude mice. This technique provides a model with more consistent tumor take and more rapid growth kinetics for human glioma cell lines that are tumorigenic in nude mice.

High-flow microinfusion: tissue penetration and pharmacodynamics.

High-flow microinfusion provides a means for delivering macromolecules to large volumes of brain in easily obtainable time intervals. Slowly degraded approximately 180-kDa macromolecules, delivered at a constant volumetric flow rate of 3 microliters/min into homogeneous brain tissue (e.g., gray matter), would penetrate to a 1.5-cm radius in 12 h. The predicted concentration profile is relatively flat until it declines precipitously at the flow front. Hence, tissues are dosed rather uniformly, providing control over the undesired toxicity that may occur with alternative methods that depend on large concentration gradients for tissue transport. The penetration advantage of high-flow (convective) over low-flow (diffusive) microinfusion has been assessed at fixed pharmacodynamic effect. A 12-h high-flow microinfusion of a macromolecule degraded with a characteristic time of 33.5 h would provide 5- to 10-fold increases in volume over low-flow infusion and total treatment volumes > 10 cm3. Slower degradation rates would result in larger treatment volumes; more rapid degradation rates would reduce the volume but still favor convective over diffusive administration. This technique may be applicable to a variety of diagnostic and therapeutic agents such as radioimmunoconjugates, immunotoxins, enzymes, growth factors, and oligonucleotides.

Neurotoxicity of immunotoxins.

Immunotoxins are being tested for the therapy of systemic cancer and brain tumors. Neurotoxicity has been dose limiting for several of these antibody conjugates given systemically. We review the animal and clinical data related to the neurotoxicity of immunotoxins in attempt to understand the molecular basis for the unexpected neural involvement and to prevent or minimize this toxicity in future clinical trials.

Convection-enhanced delivery of macromolecules in the brain.

For many compounds (neurotrophic factors, antibodies, growth factors, genetic vectors, enzymes) slow diffusion in the brain severely limits drug distribution and effect after direct drug administration into brain parenchyma. We investigated convection as a means to enhance the distribution of the large and small molecules 111In-labeled transferrin (111In-Tf; M(r), 80,000) and [14C]sucrose (M(r), 359) over centimeter distances by maintaining a pressure gradient during interstitial infusion into white matter to generate bulk flow through the brain interstitium. The volume of distribution (Vd) containing > or = 1% concentration of infusion solution increased linearly with the infusion volume (Vi) for 111In-Tf(Vd/Vi, 6:1) and [14C]sucrose (Vd/Vi, 13:1). Twenty-four hours after infusion, the distribution of 111In-Tf was increased and more homogeneous, and penetration into gray matter had occurred. By using convection to supplement simple diffusion, enhanced distribution of large and small molecules can be obtained in the brain while achieving drug concentrations orders of magnitude greater than systemic levels.

Cytotoxic ribonuclease chimeras. Targeted tumoricidal activity in vitro and in vivo.

Monoclonal antibodies to the transferrin receptor or to the T cell antigen, CD5, were chemically linked to mammalian RNase A and found to specifically inhibit protein synthesis in antigen-positive cells. Antibody-mediated specificity of these cytotoxic ribonuclease chimeras (CRCs) was demonstrated in three ways. 1) Toxicity was due to the chemical linkage of RNase to antibody, as the individual components added separately or in combination did not inhibit protein synthesis; 2) the anti-transferrin receptor CRCs inhibited protein synthesis in those cells expressing the human transferrin receptor (K562, U251, Jurkat cells) but had no detectable toxicity to cells lacking the human transferrin receptor (Vero or NIH 3T3 cells); 3) free antibody to either the human transferrin receptor (454A12 or 5E-9) or to the T cell antigen, CD5 (T101), blocked the cytotoxicity of the respective CRC. Two CRC species, designated P1 and P2, that differed in size and stoichiometry of RNase A to antibody, were purified by size-exclusion high performance liquid chromatography. The higher molecular weight P1 conjugate had an IC50 of 20-30 nM, whereas the P2 conjugate had a higher IC50 of 300-500 nM. Bioactivity could be reversibly increased more than 10-fold by freezing. The cytotoxicity of the CRCs was examined in vivo in a solid tumor animal model. Intratumoral injections of an anti-transferrin receptor CRC into established U251 human glioblastoma tumors grown in the flanks of nude mice prevented tumor growth, whereas RNase A mixed with antibody was ineffective. CRCs, therefore, express cytotoxicity in vitro and in vivo. Mammalian nucleases coupled to antibodies may be utilized as cell type-selective cytotoxins and have potential as pharmacologic reagents. The systemic toxicity and immunogenicity observed with mammalian derived cytotoxins may be significantly less than that of the currently employed plant- and bacterial-derived immunotoxins.

Intracranial meningiomas: factors that influence the development of cerebral edema after stereotactic radiosurgery and radiation therapy.

PURPOSE: To evaluate causative factors of cerebral edema after stereotactic radiosurgery or stereotactic radiation therapy in intracranial meningiomas. MATERIALS AND METHODS: Of 43 adult patients with intracranial meningiomas, three received 13.5-18-Gy single-fraction stereotactic radiosurgery; one received 19.8 Gy in three fractions, one received 42 Gy in six fractions, and 31 received 32-36 Gy in six to eight fractions of stereotactic radiation therapy; and seven received 45-54-Gy external-beam radiation with 20-28 Gy in five to seven fractions as concomitant stereotactic boosts. Brain edema was estimated by calculating the edema index. RESULTS: After irradiation, all 11 patients with parasagittal and four patients with nonparasagittal tumors developed worsening cerebral edema that necessitated the administration of steroids (P < .001). The statistically significant factors for the development of edema were parasagittal location, presence of pretreatment edema, sagittal sinus occlusion, and the use of more than 6 Gy per fraction. Five patients with parasagittal tumors developed life-threatening panhemispheric edema, which was fatal in one. The causative factors of panhemispheric edema were a large tumor, single-fraction stereotactic radiosurgery, or use of more than 6 Gy per fraction. CONCLUSION: A smaller dose per fraction and aggressive use of steroids may help prevent life-threatening complications due to worsening edema.