Comparison of the blood-brain barrier and liver penetration of acridine antitumor drugs

Summary The blood-brain barrier penetration of amsacrine and its analogs 9-({2-methoxy-4-[(methylsulfonyl)-amino]phenyl}amino)-,5-dimethyl-4-acridine carboxamide (CI-921) and M-[2-(dimethylamino)ethyl]-acridine-4-carboxamide (AC) was measured in the barbiturate-anesthetized mouse. After intracarotid administration, AC was almost completery extracted (90%) in a single transit through the brain capillaries, whereas CI-921 (20%) and amsacrine (15%) were moderately extracted. AC is retained in the brain; no loss of AC from the brain was apparent at 1, 2, 4, or 8 min after injection. In contrast, after intraportal administration, 75% of the AC, 94% of the CI-921, and 57% of the amsacrine was extracted in a single transit through the hepatic vasculature. Rather than being retained in the mouse liver, these acridine antitumor agents show time-dependent loss (t _1/2=10 min for amsacrine and AC, 24 min for CI-921). We conclude that unlike most antitumor agents, these acridine drugs appear to penetrate the blood-brain barrier readily.This study was supported by the Auckland Medical Research Foundation (New Zealand), by the Medical Research Foundation (New Zealand), by the National Science Foundation (United States/New Zealand Cooperative Science Program), by the United States Veterans Administration, and by NIH grant NS 25554     

Adeno-associated virus vector-mediated systemic delivery of IFN-beta combined with low-dose cyclophosphamide affects tumor regression in murine neuroblastoma models.

PURPOSE: Type I IFNs (IFN-alpha/beta) have shown significant antitumor activity in preclinical models but limited efficacy and significant toxicity in clinical trials. We hypothesized that the antitumor activity of type I IFNs could be enhanced by chronic, low-dose systemic delivery and sought to test this in murine neuroblastoma models. EXPERIMENTAL DESIGN: Continuous liver-generated expression of human IFN-beta (hINF-beta) was achieved through a gene therapy-mediated approach using adeno-associated virus vectors encoding hIFN-beta (AAV hINF-beta). Orthotopic localized retroperitoneal and disseminated models of neuroblastoma were established using three different xenografts. Immunohistochemical analysis and ELISA were used to evaluate the antiangiogenic effect of therapy. RESULTS: The development of both localized orthotopic (retroperitoneal) and disseminated neuroblastoma was prevented in all mice expressing hINF-beta. Continued growth of established retroperitoneal tumors, treated with AAV hINF-beta as monotherapy, was significantly restricted, and survival for mice with established, disseminated disease was significantly prolonged following administration of AAV hINF-beta. Analysis of treated tumors revealed a significant antiangiogenic effect. Mean intratumoral vessel density was diminished and expression of the angiogenic factors vascular endothelial growth factor and basic fibroblast growth factor were both decreased. Finally, combination therapy in which AAV hIFN-beta was used together with low-dose cyclophosphamide resulted in regression of both established retroperitoneal and disseminated disease. CONCLUSIONS: AAV-mediated delivery of hIFN-beta when used as monotherapy was able to restrict neuroblastoma growth due in part to inhibition of angiogenesis. When used in combination with conventional chemotherapy, AAV hIFN-beta was able to effect complete tumor regression.     

The binding of amsacrine to human plasma proteins

Determination of amsacrine plasma protein binding by both equilibrium dialysis and ultracentrifugation gave similar results and indicated that amsacrine is highly bound (approximately 97%) in human plasma. This binding is independent of amsacrine concentration over the range 1-100 mumol litre-1, but is very sensitive to plasma pH and, to a lesser extent, to temperature. Approximately 20% of the drug appeared to be covalently bound to plasma proteins. Amsacrine was bound by all plasma proteins investigated including albumin, alpha 1-acid glycoprotein and various gamma-globulins. The binding to albumin appeared to occur by two processes, a saturable process at a single site with a KD of 13.9 mumol litre-1 and a non-saturable process. Despite differences in individual protein concentrations, no significant difference was observed in the unbound amsacrine fraction in plasma from patients receiving this drug for treatment of acute myelogenous leukaemia and plasma from healthy individuals.     

Self-help materials for anxiety: a randomized controlled trial in general practice.

The efficacy of a self-help package in treating chronic anxiety was evaluated in a randomized controlled trial in which the intervention group received self-help materials in the form of an audiotape and booklet, in addition to their current treatment. The intervention was successful in terms of mean depression scores (P = 0.01), anxiety scores (P = 0.04) and general health questionnaire scores (P = 0.02) which were significantly lower for the intervention group than for the controls. In addition, the depression scores fell faster for the intervention group than for the controls. The overall mean reduction in three months in adjusted depression scores was approximately two points greater for the intervention group than for the controls (P = 0.02). Clinicians welcomed the package as a valuable addition to the therapies available for managing chronic anxiety problems. Further studies should include larger sample sizes, taking into account the non-response to postal questionnaires over time.     

Body dissatisfaction prospectively predicts depressive mood and low self-esteem in adolescent girls and boys.

This research examined whether body dissatisfaction prospectively predicted depressive mood and low self-esteem in adolescent girls and boys 5 years later. Participants were early-adolescent girls (n = 440, Time 1 M age = 12.7 years) and boys (n = 366, Time 1 M age = 12.8 years) and midadolescent girls (n = 946, Time 1 M age = 15.8 years) and boys (n = 764, Time 1 M age = 15.9 years). After controlling for Time 1 of the relevant dependent variable, ethnicity, socioeconomic status, and body mass index, Time 1 body dissatisfaction was a unique predictor of Time 2 depressive mood and low self-esteem in early-adolescent girls (depressive mood: F = 4.80, p < .05; self-esteem: F = 9.64, p < .01) and midadolescent boys (depressive mood: F = 12.27, p < .001; self-esteem: F = 9.38, p < .01) but not in early-adolescent boys or midadolescent girls. These findings are consistent with the hypothesis that body dissatisfaction is a risk factor for depressive mood and low self-esteem in both girls and boys but in different phases of adolescence.     

The use of natural interferon alpha conjugated to a monoclonal antibody anti mammary epithelial mucin (Mc5) for the treatment of human breast cancer xenografts

Summary An immunoconjugate composed of natural interferon (nIFN) bound in a noncleavable fashion to a monoclonal antibody (MoAb) recognizing a breast epithelial membrane mucin (Mc5) was used to treat xenografts of a human mammary carcinoma cell line (MCF-7) growing in nude mice. The immunoconjugate (nIFN/Mc5) was administered as 20 intralesional (i.l.) injections to 1 of 2 xenografts in each animal. It was found that nIFN/Mc5 produced a significant enhancement of the growth inhibitory actions of nIFN on the injected tumors. Further enhancement was obtained when nIFN or nIFN together with Mc5 (at a dose 10 times larger than that present in nIFN/Mc5) were added to the immunoconjugate. Biodistribution experiments showed that the uptake of¹²⁵I-nIFN/Mc5 by the tumors was greater and its elimination slower than for¹²⁵I-nIFN alone or conjugated to irrelevant mouse IgG₁. In addition, the immunoconjugate up-regulated the antigenic expression of a breast epithelial membrane mucin by the carcinoma cells, an up-regulation which was not significantly different from that produced by nIFN alone. The contralateral noninjected tumors exposed to systemic levels of the immunoconjugate showed an enhancement of antitumor effects, but to a lesser extent than the injected tumors. These findings suggest that the enhancement of the growth inhibitory action of the immunoconjugate was related to the specific binding of Mc5 which targeted the IFN to the carcinoma cells and impeded its elimination. It is likely that the targeting was favored by the IFN-mediated up-regulation of antigenic expression by the carcinoma cells, thereby producing a cascade of interrelated effects. The results of this study point out the feasibility and potential usefulness of IFN treatment by means of immunoconjugates as well as the worth of pursuing and improving this form of therapy.     

Tumour profile ofN-[2-(dimethylamino)ethyl]acridine-4-carboxamide after intraperitoneal administration in the mouse

N-[2-(dimethylamino)ethyl]acridine-4-carboxamide (AC) is an experimental antitumour agent that is being considered for phase I trials. After i.p. administration of 150 mg/kg [³H]-AC to tumour-bearing mice, AC was absorbed rapidly into the plasma and tissues such as the heart, liver, kidney and brain but more slowly into the s.c. tumour. The maximal AC concentration (86±36 mol/kg) in the tumour occurred at 35–60 min and was 3-fold the maximal plasma concentration, which occurred at 15 min. Although higher maximal concentrations were observed in other tissues, these concentrations fell rapidly in parallel with plasma concentrations. In contrast, AC concentrations in the tumour remained elevated, thet1/2 value (16.3 h) and mean residence time (MRT, 9.5 h) being prolonged in comparison with those in the plasma and other tissues (t1/2 range, 1.0–2.9 h; MRT, 1.2–1.4 h). AC concentrations were not detectable by our high-performance liquid chromatographic (HPLC) method (limit of detection, 0.02 mol/l) in the plasma or other tissues at 24 or 48 h after administration but were measurable in the tumour (1.6±0.8 and 0.6±0.3 mol/kg, respectively). Radioactivity concentrations in the plasma, tissues and tumour were very variable but were greater than the corresponding levels of unchanged parent AC. By 24 h, radioactivity concentrations in the plasma, tissues and tumour had fallen to similar levels with prolonged elimination profiles. Thus, the exposure of the s.c. implanted tumour to a threshold AC concentration for a prolonged time (>24 h) may partly explain the greater efficacy of AC against this tumour, whereas the shorter period of exposure of blood and other tissues may explain its low haematological toxicity.