Imatinib mesylate (STI-571 Glivec, Gleevec) is an active agent for gastrointestinal stromal tumours, but does not yield responses in other soft-tissue sarcomas that are unselected for a molecular target. Results from an EORTC Soft Tissue and Bone Sarcoma Group phase II study.

The aim of this study was to assess the antitumour response and time to progression (TTP) of patients treated with imatinib mesylate (Glivec, Gleevec, formerly STI-571) who had advanced and/or metastatic gastrointestinal stroma tumours (GIST) or other soft tissue sarcomas (STS). Patients with measurable lesions and adequate organ function were entered. They were treated with imatinib mesylate at the dose of 400 mg twice daily (bid). All tumours were subject to a stringent pathological review by an expert panel. Immunohistochemical expression of KIT expression was evaluated. A total of 51 patients (27 GIST, 24 other STS), median age 53 years, median World Health Organization (WHO) performance score 1, were entered. 71% of the patients had received prior chemotherapy. The most frequent side-effects were anaemia (92%), periorbital oedema (84%), skin rash (69%), fatigue (76%), nausea (57%), granulocytopenia (47%) and diarrhoea (47%). Most of these side-effects were mild to moderate and no patient was taken off study due to side-effects. Skin rash and periorbital oedema frequently seem to be self limiting, despite continued treatment. In GIST patients, the current response rates (RRs) are 4% complete remission (CR), 67% partial remission (PR), 18% stable disease (SD) and 11% progression (PD). 73% of GIST patients are free from progression at 1 year. In the other STS group, there were no objective responses. The median time to progression in this subgroup was only 58 days. Imatinib mesylate is well tolerated at a dose of 400 mg bid. This dose is active in patients with KIT-positive GIST, but patients with other STS subtypes unselected for a molecular target are unlikely to benefit.

Influence of retigabine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice.

Retigabine (D-2319, 0.5-20 mg/kg i.p.) antagonised dose dependently audiogenic seizures in DBA/2 mice. Retigabine at 0.5 mg/kg i.p., a dose that per se did not affect the occurrence of audiogenic seizures significantly, potentiated the anticonvulsant activity of carbamazepine, diazepam, felbamate, lamotrigine, phenytoin, phenobarbital and valproate against sound-induced seizures in DBA/2 mice. The degree of additivity for the effect induced by retigabine was greatest for diazepam, phenobarbital, phenytoin and valproate, less for carbamazepine and lamotrigine and least for felbamate. The increase in anticonvulsant activity was usually associated with a comparable increase in motor impairment. However, the therapeutic index of combined treatment (drugs plus retigabine), was more favourable than the same drug plus vehicle. Since retigabine had no significant influence on the total and free plasma levels of the anticonvulsant drugs, pharmacokinetic interactions, in terms of total or free plasma levels, are not probable. However, the possibility that retigabine modifies the clearance of the anticonvulsant drugs from the brain cannot be excluded. Retigabine had no significant effect on the hypothermic effects of the anticonvulsants tested. In conclusion, retigabine showed an additive effect when administered in combination with classical anticonvulsants, most notably diazepam, phenobarbital, phenytoin and valproate.

Randomized phase II study of docetaxel versus doxorubicin in first- and second-line chemotherapy for locally advanced or metastatic soft tissue sarcomas in adults: a study of the european organization for research and treatment of cancer soft tissue and bone sarcoma group.

PURPOSE: To assess antitumor response and time to progression (TTP) with docetaxel compared with doxorubicin in first-line treatment of advanced and/or metastatic soft tissue sarcoma. PATIENTS AND METHODS: Patients with measurable soft tissue sarcoma lesions and adequate bone marrow, liver, and renal function were entered onto the study. They were randomized to either docetaxel 100 mg/m(2) given as a 1-hour intravenous infusion every 3 weeks or doxorubicin 75 mg/m(2) given as a bolus injection every 3 weeks. A maximum of seven cycles of treatment were scheduled. The study was designed as a randomized phase III study evaluating TTP by log-rank model. There was a clause for premature closure of the trial if fewer than five responses were observed among the first 25 assessable patients in the docetaxel treatment arm. RESULTS: Eighty-six patients were entered onto the study; 85 were assessable for toxicity and 83 for response. The rate of severe granulocytopenia was not significantly different between the two arms. Nausea (P =.001), vomiting (P <.001), and stomatitis (P =.005) were more common with doxorubicin therapy, whereas neurotoxicity was more frequent with docetaxel treatment. The response rate to doxorubicin therapy was 30% (95% confidence interval, 17% to 46%), whereas no responses to docetaxel therapy were seen (P <.001). In view of this, the trial was closed prematurely and the phase III study part was not conducted. CONCLUSION: Docetaxel is inactive in soft tissue sarcomas and cannot be recommended for further use in treatment of this disease.

Effects of adenosine receptor agonists and antagonists on audiogenic seizure-sensible DBA/2 mice.

We have studied the effects of selective and non-selective adenosine receptor agonists and antagonists in audiogenic-seizure-sensitive DBA/2 mice, an animal model of generalized reflex epilepsy. With the exception of the adenosine A3 receptor agonist, N6-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine (IB-MECA), all the agonists studied prevented the development of audiogenic seizures in a dose-dependent manner. The ED50 values against the clonic phase of the audiogenic seizures were low, that is: 0.06 mg/kg, i.p., for the adenosine A1 receptor agonist, 2-chloro-N6-cyclopentyladenosine (CCPA), 0.02 and 0.03 mg/kg, i.p., for the adenosine A2A receptor agonists, 2-(4-(2-carboxyethyl)-phenylamino)-5'-N-ethylcarboxamidoadenosine (CGS 21680) and 2-hexynyl-5'-N-ethyl-carboxamidoadenosine (2-HE-NECA), and 0.7 mg/kg, i.p., for the adenosine A1/A3 receptor agonist, N6-2-(4-aminophenyl)ethyladenosine (APNEA). Conversely, the non-selective agonist, N-ethyl-carboxamidoadenosine (NECA), was highly potent, the ED50 being 0.0005 mg/kg, i.p. In the absence of auditory stimulation, the adenosine receptor antagonists increased the incidence of both clonic and tonic seizures in DBA/2 mice. The ED50 values were: for caffeine, 207.5 mg/kg, i.p., for the adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), 327.8 mg/kg i.p., for the adenosine A2A receptor antagonists, 3,7-dimethyl-1-propylxanthine (DPMX), 86.7 mg/kg i.p., for the (E,18%-Z,82%)7-methyl-8-(3,4-dimethoxystyryl)-1,3-dipropylxanthine (KF 17837), 69.1 mg/kg i.p., and 5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo-(4,3-c)1,2,4-triazolo(1,5 -c)-pyrimidine (SCH 58261), 321.8 mg/kg i.p. The rank order of convulsant potency in our epileptic model, following intracerebroventricular administration, was DPCPX > DMPX > 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine (CSC) > KF 17837 > Caffeine > SCH 58261 > 5-amino-9-chloro-2-(2-furyl)-1,2,4-triazolo(1,5-c)quinazoline (CGS 15943). Following a subconvulsant audiogenic stimulus of 83 dB, all adenosine receptor antagonists induced both tonic and clonic seizures. The ED50 values for such proconvulsant effects were: for caffeine 0.04 mg/kg, i.p., for the adenosine A receptor antagonist, DPCPX, 5.84 mg/kg, i.p., for the adenosine A2A receptor antagonists, DMPX, 0.02 mg/kg, i.p., CGS 15943, 0.29 mg/kg i.p., KF 17837, 0.57 mg/kg, i.p., CSC 0.12 mg/kg, i.p. and SCH 58261 0.07 mg/kg, i.p., respectively. These data suggest that stimulation of adenosine A1 and A2A receptors is involved in the suppression of seizures.

Effects of some AMPA receptor antagonists on the development of tolerance in epilepsy-prone rats and in pentylenetetrazole kindled rats.

The non-selective alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptor antagonists, 2,3-benzodiazepine derivatives CFM-1 (3,5-dihydro-7,8-dimethoxy-1-phenyl-4H-2,3-benzodiazepin-4-one) and CFM-2 (1-(4'-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin -4-one), following intraperitoneal (i.p.) administration, were studied against audiogenic seizures in genetically epilepsy-prone rats (GEPRs) or pentylenetetrazole induced kindling in rats. After acute i.p. administration the ED50 values of CFM-1 against the clonic and tonic phases of the audiogenic seizures 30 min after pretreatment were 40 (16-100) and 13 (8-25) micromol kg(-1), respectively. The animals used for chronic study were treated i.p. daily (at 10 h) for 4 weeks with CFM-1 (20 or 50 micromol kg(-1)). Chronic treatment for 2 weeks with CFM-1 gave ED50 values against clonic and tonic seizures of 39 (22-69) and 16 (8-25) micromol kg(-1), respectively, whereas chronic treatment for 4 weeks gave ED50 values against clonic and tonic seizures of 42 (18-98) and 17 (7-41.3) micromol kg(-1), respectively. The duration of anticonvulsant activity observed between 0.5 and 4 h following administration of CFM-1 was similar for acute and chronic treatment. Two groups of Sprague-Dawley rats received CMF (20 or 50 micromol kg(-1)) 30 min before a subconvulsant dose of pentylentetrazole (25 mg kg(-1) i.p.) which is able to increase seizure severity in control animals (i.e., chemical kindling). Pretreatment with CFM-2 delayed the progression of seizure rank during repeated administration of pentylentetrazole. At the end of the period of repeated pentylentetrazole treatment (6 weeks) the mean seizure score was 0 in vehicle treated controls, 4.3 in animals treated with vehicle + pentylentetrazole, 2.2 in rats treated chronically with CFM-2 (20 micromol kg(-1) i.p.) + pentylentetrazole and 1.0 in rats treated repeatedly with CFM-2 (50 micromol kg(-1) i.p.) + pentylenetetrazole. CFM-2 was also able to antagonize the long-term increase in sensitivity of the convulsant effects of GABA function inhibitors in pentylentetrazole-kindled animals. Thus, the administration of a challenge dose of pentylentetrazole (15 mg kg(-1) i.p.) or picrotoxin (1.5 mg kg(-1) i.p.) 15 or 30 days after the end of the repeated treatment showed that animals treated with CFM-2 were significantly protected against seizures induced by pentylentetrazole or picrotoxin. The data suggest that, following repeated treatment, tolerance to the novel AMPA receptor antagonists does not develop (CFM-1 in genetically epilepsy-prone rats and CFM-2 in the pentylentetrazole kindling model of epilepsy). Thirteen minutes after drug injection on days 1, 14 and 28 of chronic treatment the motor impairment induced by these compounds was studied with a rotarod apparatus. The TD50 values for CFM-1 or CFM-2-induced impairment of locomotor performance were similar following acute and repeated treatment. The data also suggest that some novel 2,3-benzodiazepines may have clinical potential for some types of epilepsy.

Is the mitochondrial benzodiazepine receptor involved in the control of airway smooth muscle tone?

1. In addition to binding to GABAA receptors in the central nervous system, benzodiazepines have also been reported to recognize high affinity binding sites in several different peripheral tissues. 2. These peripheral benzodiazepine receptors likely consist of distinct integral membrane proteins, which are predominantly localized in the outer mitochondrial membrane and may be associated to form a heteropolymeric receptor complex. One such protein, identified for its ability to bind a class of benzodiazepines and isoquinolines, has been purified and the corresponding complementary DNA (cDNA) has been cloned and characterized. Furthermore, the structure of the rat gene encoding this protein has been clarified, thus potentially opening new insights into the molecular mechanisms responsible for receptor regulation. 3. Although the exact physiologic and/or pharmacologic role of peripheral benzodiazepine receptors is still unknown, their wide tissue distribution suggests an involvement in many cellular phenomena. 4. In particular, several lines of investigation indicate that these receptors, densely expressed on airway smooth muscle of various species, may contribute to the modulation of bronchomotor tone and perhaps to the pathogenesis of asthma and airway hyperresponsiveness.

Tolerance to anticonvulsant effects of some benzodiazepines in genetically epilepsy prone rats.

The development of tolerance to the anticonvulsant effects of clonazepam, clobazam, and diazepam were studied in genetically epilepsy-prone rats following intraperitoneal (IP) or oral administration. The anticonvulsant effects were evaluated on seizures evoked by means of auditory stimulation (109 dB, 12-16 kHz). All compounds showed 60 min after IP injection antiseizure activity with ED50 against clonus of 0.24 mumol kg-1 for clonazepam, 0.72 mumol kg-1 for diazepam, and 3.9 mumol kg-1 for clobazam. After 120 min of oral administration the ED50 against clonus of 2.37 mumol kg-1 for clonazepam, 15.8 mumol kg-1 for diazepam, and 30 mumol kg-1 for clobazam. The dose chosen for the chronic treatment were 2.5 mumol kg-1 for clonazepam, 15 mumol kg-1 for diazepam, and 30 mumol kg-1 for clobazam. The animals were treated three times daily for 4 or 6 weeks. Auditory stimulation was administered 60 min after drug IP injection on various days. During treatment, tolerance was observed as a loss of drug anticonvulsant effects. No changes of occurrence of audiogenic seizures was observed in rats treated with vehicle. Tolerance to the anticonvulsant activity developed most rapidly during clobazam treatment, less rapidly following diazepam treatment, and most slowly during clonazepam treatment. Sixty minutes after IP injection on various days of chronic treatment the motor impairment induced by these benzodiazepines was also studied by means of a rotarod apparatus. The tolerance to the motor impairment developed more rapidly than the anticonvulsant effects. The response to auditory stimulation to benzodiazepines was stopped 24 and 48 h after chronic treatment with these compounds, showing no residual drug effects and that rats were still tolerant. The genetically epilepsy-prone rats is a reliable and sensitive model for studying long-term effects of anticonvulsant drugs.

Propionyl-L-carnitine limits chronic ventricular dilation after myocardial infarction in rats.

To determine whether propionyl-L-carnitine (PLC) administration ameliorates ventricular remodeling after myocardial infarction, we performed coronary occlusion in rats and examined the long-term effects of the drug 19-24 wk after surgery. In view of the well-established role of angiotensin-converting enzyme (ACE) inhibitors in the reduction of ventricular dilation after infarction, the therapeutic impact of oral PLC (60 mg/kg) was compared with that of enalapril (1 mg/kg). Infarct size measured planimetrically was found to be comparable in untreated, PLC-treated, and enalapril-treated rats, averaging 40-46% of the left ventricular free wall. Heart weight was increased 14, 16, and 11% with no treatment, with PLC, and with enalapril, respectively. The relationship between left ventricular filling pressure and chamber volume demonstrated that PLC and enalapril significantly prevented the expansion in cavitary size after infarction. These protective influences were observed throughout the range of filling pressures measured, from 0 to 30 mmHg. At a uniform reference point of filling pressure of 4 mmHg, untreated infarcted hearts showed an expansion in ventricular volume of 2.17-fold (P < 0.0001). Corresponding increases in this parameter after PLC and enalapril were 36 and 43%, respectively, both not statistically significant. Moreover, PLC was capable of reducing the alterations in myocardial compliance associated with myocardial infarction. In conclusion, PLC reduces the magnitude of decompensated eccentric hypertrophy produced by myocardial infarction in a manner similar to that found with ACE inhibition.

L-arginine potentiates excitatory amino acid-induced seizures elicited in the deep prepiriform cortex.

Microinjection of N-methyl-D-aspartate (NMDA; 1 and 2.5 nmol) or kainate (KA; 50 pmol) into the deep prepiriform cortex elicited behavioral signs of seizure activity. No epileptiform activity was observed after deep prepiriform cortex microinjection of either L-arginine (L-Arg, 5 and 10 nmol) or its D-enantiomer, D-arginine (D-Arg, 2.5-10 nmol). However, both the seizure score and the incidence of electroencephalographic (EEG) epileptic discharges elicited by NMDA (1 and 2.5 nmol) and KA (50 pmol) were significantly increased by L- but not D-Arg. The facilitatory effects of L-Arg on seizure activity elicited by both NMDA and KA were dose-dependent and could be prevented by co-administration of L-Arg (10 nmol) and the nitric oxide (NO) synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 20 nmol). Motor and electrocortical seizures were observed after microinjection of the NO donor sodium nitroprusside (SNP; 5 to 20 nmol) into the deep prepiriform cortex. Infusion of methylene blue (20 nmol), a soluble guanylate cyclase inhibitor, protected against SNP-induced seizures. Furthermore, prior infusion of a subconvulsant dose of SNP into the deep prepiriform cortex significantly potentiated the seizure activity elicited by either NMDA (1 and 2.5 nmol) or KA (50 pmol). These results support the proposal that NO is formed from L-Arg upon excitatory amino acid receptor activation within the deep prepiriform cortex, thereby contributing to the genesis of seizure activity.

Effects of antiepileptic drugs, calcium channel blockers and other compounds on seizures induced by activation of voltage-dependent L calcium channel in DBA/2 mice.

1. The convulsant activity of the calcium voltage L-channel agonist Bay k 8644 was studied in genetically epilepsy prone DBA/2 mice. 2. Seizures were induced by intracerebroventricular injection of Bay k 8644. 3. These seizures were reversed by some calcium channel blockers such as dihydropyridines, some excitatory amino acid antagonists such as 2-amino-7-phosphonoeptanoate and CPPene, 2-chloro-adenosine, some anticonvulsant drugs such as magnesium valproate, diazepam and clonazepam and two kappa opioid agonists (U-50488H and U-54494A). 4. The remaining antiepileptic drugs (carbamazepine, phenytoin, phenobarbital and trimethadione) were ineffective in this respect. Other anticonvulsant compounds such as dizocilpine (MK 801), ketamine and drugs enhancing GABAergic transmission did not significantly affect the clonic phase of the seizures induced by Bay k 8644. 5. These results show that Bay k 8644 seizures are relatively resistant to some anticonvulsant compounds. The role of some neurotransmitters on seizures induced by Bay k 8644 is discussed.

Cardiovascular effects of neurotensin and some analogues on rats.

When administered in vivo into the femoral vein of normotensive rats, neurotensin, neurotensin-(8-13), and [D-Lys8]neurotensin-(8-13) decreased diastolic blood pressure in a dose-dependent manner, without change in heart rate. All three peptides evoked tachyphylaxis and a triphasic depressor-pressor-depressor, response at higher doses. The rank order of potency was neurotensin greater than [D-Lys8]neurotensin-(8-13) greater than neurotensin-(8-13). In organ chamber experiments, both neurotensin and neurotensin-(8-13) at a range of concentrations which induced dose-dependent decreases in blood pressure, did not significantly change tension in rat aorta rings with or without endothelium. In contrast, [D-Lys8]neurotensin-(8-13) induced weak dose-dependent relaxation of both rings with or without endothelium. However, this effect was not obtained at concentrations able to decrease the blood pressure. Indomethacin did not change the vasodilator effect of [D-Lys8]neurotensin-(8-13). There was no correlation between the vasodilator effect of this peptide and its ability to decrease blood pressure. These experiments suggest that the hypotension was not due to a direct vasodilator effect on the smooth muscle. In addition, since the rank order of peptide potency was opposite of those found in previous studies of second messenger synthesis and binding to neural tissue, these data suggest that there is a second receptor for neurotensin or that neurotensin can also bind to a different unknown receptor.

Pharmacological, hemodynamic and biochemical mechanisms involved in the blood pressure lowering effects of pergolide, in normotensive and hypertensive dogs.

In pentobarbital-anesthetized normotensive dogs, clonidine (20.0 micrograms/kg i.v.), in contrast to pergolide (30.0 micrograms/kg i.v.), reduced significantly both aortic blood pressure and plasma concentration of norepinephrine. However, in dogs that had been made hypertensive by sectioning the vagi and carotid sinus nerves, pergolide, like clonidine, lowered the blood pressure and plasma concentrations of epinephrine and norepinephrine that were enhanced markedly by deafferentation. Furthermore, in this preparation pergolide decreased the calculated resistance in vascular regions supplied by the upper abdominal aorta and the innervated femoral and renal arteries, but it increased vascular resistance in the denervated hind leg. Pergolide (1.0 microgram/kg) injected intracisternally (i.c.m.) induced a fall in blood pressure of comparable magnitude to that produced by a 30 times higher i.v. dose. Intravenously and i.c.m. administered pergolide lowered blood pressure by acting at distinct anatomical sites inasmuch as i.v. sulpiride blocked the effects of i.v. but not i.c.m. pergolide. The combination of sulpiride plus yohimbine injected i.c.m. was necessary to abolish the decrease in blood pressure evoked by i.c.m. pergolide. In atropinized spinal dogs, i.v. pergolide inhibited the vasoconstriction elicited by electrical stimulation of the lumbar sympathetic chain, an effect which was antagonized by sulpiride. Similarly, pergolide (30.0 micrograms/kg i.v.) like clonidine, reduced the heart rate and coronary venous plasma norepinephrine concentration raised by sustained electrical stimulation of the cardioaccelerator nerve. Sulpiride, but not phentolamine, antagonized this pergolide-induced inhibition of sympathetic nerve function. In chlorisondamine-pretreated dogs, pergolide produced a transient pressor response due to stimulation of postsynaptic vascular alpha-2 adrenoceptors. In conclusion, the failure of i.v. pergolide to decrease aortic blood pressure in pentobarbital-anesthetized normotensive dogs is presumably due to the inability of pergolide to produce a significant inhibition of the vascular sympathetic tone in this preparation. However, in neurogenic hypertensive dogs which are characterized by an elevated level of sympathetic drive, i.v. pergolide reduced blood pressure and aortic plasma norepinephrine concentration. These effects of pergolide are compatible with a DA-2 dopamine receptor stimulation on peripheral sympathetic nerve fibers. In contrast, the antihypertensive effects of i.c.m. pergolide would appear to be mediated by both alpha-2 adrenoceptors and DA-2 dopamine receptors located within the central nervous system.

Cardiovascular effects of tetanus toxin after systemic and intraventricular administration in rats.

A single intraperitoneal injection of tetanus toxin (50,100 and 200 minimum lethal dose per rat) produced a significant and dose-dependent increase in systemic blood pressure and heart rate in conscious rats. On the contrary, tetanus toxin, given directly into the third cerebral ventricle (20 and 40 minimum lethal dose), produced a gradual and dose-dependent decrease in blood pressure accompanied by bradycardia. In conclusion, the present findings show that tetanus toxin is able to affect cardiovascular activity and it is suggested that this may be due to an interference with central GABAergic mechanisms.