Zoledronic acid improves clinical outcomes in patients with bone metastatic hormone-naïve prostate cancer in a multicenter clinical trial.

AIM: To assess whether zoledronic acid (ZOL) adds to the effect of combined androgen blockade (CAB) in patients with hormone-naive bone metastatic prostate cancer. PATIENTS AND METHODS: Patients were treated with either a combination of CAB (luteinizing hormone-releasing hormone agonist and bicalutamide) and ZOL (CAB-Z group) or CAB-alone (historical control patients, CAB-C group). ZOL was injected intravenously at 4 mg every 4 weeks. One hundred and five and 100 patients among 205 enrolled patients were assigned to the CAB-Z group and CAB-C group, respectively. The time to prostate-specific antigen (PSA) failure in patients in the CAB-Z group was compared to that in the CAB-C group. The primary end-point of the study was the time-to-PSA failure. RESULTS: PSA and serum N-telopeptide of type I collagen (NTx) levels were examined before treatment and every 3 months after treatment. PSA failure occurred in 42 (40.0%) patients in the CAB-Z group and 48 (48.0%) patients in the CAB-C group. The biochemical recurrence-free rate was significantly lower in patients in the CAB-C group (p=0.004, by log-rank test). The categorical biopsy Gleason score pre-treatment serum NTx and treatment with ZOL were shown to be independent predictors of PSA failure-free survival time (p=0.040, p=0.005 and p=0.026, respectively). CONCLUSION: ZOL given with CAB as initial treatment delays the time-to-PSA failure in patients with hormone-naive bone metastatic prostate cancer.

Progress in pursuit of therapeutic A2A antagonists: the adenosine A2A receptor selective antagonist KW6002: research and development toward a novel nondopaminergic therapy for Parkinson's disease.

Research and development of the adenosine A2A receptor selective antagonist KW6002 have focused on developing a novel nondopaminergic therapy for Parkinson's disease (PD). Salient pharmacologic features of KW6002 were investigated in several animal models of PD. In rodent and primate models, KW6002 provides symptomatic relief from parkinsonian motor deficits without provoking dyskinesia or exacerbating existing dyskinesias. The major target neurons of the A2A receptor antagonist were identified as GABAergic striatopallidal medium spiny neurons. A possible mechanism of A2A receptor antagonist action in PD has been proposed based on the involvement of striatal and pallidal presynaptic A2A receptors in the "dual" modulation of GABAergic synaptic transmission. Experiments with dopamine D2 receptor knockout mice showed that A2A receptors can function and anti-PD activities of A2A antagonists can occur independent of the dopaminergic system. Clinical studies of KW6002 in patients with advanced PD with L-dopa-related motor complications yielded promising results with regard to motor symptom relief without motor side effects. The development of KW6002 represents the first time that a concept gleaned from A2A biologic research has been applied successfully to "proof of concept" clinical studies. The selective A2A antagonist should provide a novel nondopaminergic approach to PD therapy.

Adenosine modulates the striatal GABAergic inputs to the globus pallidus via adenosine A2A receptors in rats.

Previous studies have shown presynaptic modulation of adenosine A(2A) receptors for GABAergic synaptic transmission in the globus pallidus (GP). The pallidal A(2A) receptor-mediated modulation is caused by an action on the terminals of striatopallidal medium spiny neurons (MSNs) and/or axon collaterals of GP neurons. Herein, we examined the precise target neurons of the A(2A) receptor-mediated modulation. Activation of A(2A) receptors enhanced striatopallidal GABAergic transmission onto GP neurons, accompanied by a reduction in the paired-pulse facilitation, indicating the presynaptic contribution of A(2A) receptors at terminals of striatopallidal MSNs in the GP. Besides, no A(2A) receptor mRNA was detected in GP neurons by single-cell reverse transcription-polymerase chain reaction analysis, implying no contribution of axon collaterals of GP neurons to the A(2A) receptor regulation. These results demonstrate that the target neurons of adenosinergic modulation via A(2A) receptors in the GP are the striatopallidal MSNs.

Distribution of adenosine A(2A) receptor antagonist KW-6002 and its effect on gene expression in the rat brain.

A novel adenosine A(2A) receptor selective antagonist, KW-6002 [(E)-1,3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dihydro-1H-purine-2,6-dione], possesses antiparkinsonian activities in rodent and primate models. In the present study, we investigated the distribution of [14C]KW-6002 in forebrain after oral administration at pharmacologically effective doses. Also, we monitored the effects of the compound on preproenkephalin (PPE) and preprotachykinin (PPT) gene expression in rat striatum. The highest level of radioactivity was observed in the striatum after oral administration of [14C]KW-6002; 30 min after 0.1 and 0.3 mg/kg, the density values in the striatum were 2.45 and 2.43 times higher than those in a reference region (frontal cortex), respectively. At the dose of 3 mg/kg, p.o., the ratio was only 1.58 and the compound was distributed more extensively in the brain. The distribution pattern and intensity of radioactivity were maintained even 90 min after the administration of [14C]KW-6002. Oral administration of KW-6002 (0.3 and 3 mg/kg/day) to rats for 14 days reversed the increased gene expression of PPE in striatum that had been depleted of dopamine by prior treatment with 6-hydroxydopamine (6-OHDA). On the other hand, KW-6002 did not alter the decreased gene expression of PPT in 6-OHDA-treated rats. These results are the first to show directly that orally administered KW-6002 is distributed selectively to the striatum and that it modulates the activity of striatopallidal enkephalin-containing neurons but not striatonigral substance P-containing neurons.

Potent and selective inhibitors of platelet-derived growth factor receptor phosphorylation. 1. Synthesis, structure-activity relationship, and biological effects of a new class of quinazoline derivatives.

A new series of 4-[4-(N-substituted carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazoline derivatives were found to show potent and selective inhibition of platelet-dervied growth factor (PDGF) receptor phosphorylation. In this exploration of the structure-activity relationships (SARs) of the prototype inhibitor KN1022, the 4-nitrophenylurea moiety was probed. We found that 4-substitution on the phenyl ring was optimal and the introduction of more than two substituents on the phenyl ring decreased activities. Bulky substituents on the phenyl ring enhanced activities. Thiourea analogues were also prepared, and the SARs were found to be slightly different from those of the urea derivatives. Through this research, we obtained some potent KN1022 derivatives such as 4-(4-methylphenoxy)phenyl (36, IC(50) 0.02 micromol/L), 4-tert-butylphenyl (16, IC(50) 0.03 micromol/L), and 4-phenoxyphenyl (21, IC(50) 0.08 micromol/L) analogues, which had almost a 10-fold increase in activity against KN1022. These potent compounds retained their high selectivity against the PDGF receptor family similar to KN1022. We also observed that these compounds could inhibit the PDGF-BB-induced proliferation of porcine vascular smooth muscle cells without cell toxicity almost at the same IC(50) values observed for PDGF receptor phosphorylation. To evaluate the biological effects in vivo, we selected some analogues on the basis of the measurement of the plasma drug concentration after oral administration to rats. Oral administration of the 4-chlorophenyl (6), 4-bromophenyl (9), or 4-isopropoxyphenyl (20) analogue to Sprague-Dawley rats (30 mg/kg, twice daily) resulted in significant inhibition (24-38%) of neointima formation in the carotid artery of the balloon catheter deendothelialized vessel in the rats. Therefore, 4-[4-(N-substituted carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazoline derivatives, which are potent inhibitors of PDGFR phosphorylation, may be expected to represent a new therapeutic approach for the treatment of various aspects of atherosclerosis and other cellular proliferative disorders.

Presynaptic adenosine A2A receptors enhance GABAergic synaptic transmission via a cyclic AMP dependent mechanism in the rat globus pallidus.

1. We previously reported a presynaptic facilitatory action of A(2A) receptors on GABAergic synaptic transmission in the rat globus pallidus (GP). In the present study we identify the intracellular signalling mechanisms responsible for this facilitatory action of A(2A) receptors, using biochemical and patch-clamp methods in rat GP slices. 2. The adenosine A(2A) receptor selective agonist CGS21680 (1, 10 microM) and the adenylyl cyclase activator forskolin (1, 10 microM) both significantly increased cyclic AMP accumulation in GP slices. The CGS21680 (1 microM)-mediated increase in cyclic AMP was inhibited by the A(2A) receptor selective antagonist KF17837 (10 microM). 3. In an analysis of miniature inhibitory postsynaptic currents (mIPSCs), forskolin (10 microM) increased the mIPSC frequency without affecting their amplitude distribution, a result similar to that previously reported with CGS21680. 4. The adenylyl cyclase inhibitor 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (SQ22,536, 300 microM) abolished the CGS21680-induced enhancement in the frequency of mIPSCs. 5. H-89 (10 microM), a selective inhibitor for cyclic AMP-dependent protein kinase (PKA), blocked the CGS21680-induced enhancement of the mIPSC frequency. 6. The calcium channel blocker CdCl(2) (100 microM) did not prevent CGS21680 from increasing the frequency of mIPSCs. 7. These results indicate that A(2A) receptor-mediated potentiation of mIPSCs in the GP involves the sequential activation of the A(2A) receptor, adenylyl cyclase, and then PKA, and that this facilitatory modulation could occur independently of presynaptic Ca(2+) influx.