Preclinical tolerance evaluation of the addition of a cisplatin-based dry powder for inhalation to the conventional carboplatin-paclitaxel doublet for treatment of non-small cell lung cancer.

Despite the advances in targeted therapies and immunotherapy for non-small cell lung cancer (NSCLC) patients, the intravenous administration of carboplatin (CARB) and paclitaxel (PTX) in well-spaced cycles is widely indicated for the treatment of NSCLC from stage II to stage IV. Our strategy was to add a controlled-release cisplatin-based dry-powder for inhalation (CIS-DPI-ET) to the conventional CARB-PTX-IV doublet, administered during the treatment off-cycles to intensify the therapeutic response while avoiding the impairment of pulmonary, renal and haematological tolerance of these combinations. The co-administration of CIS-DPI-ET (0.5 mg/kg) and CARB-PTX-IV (17-10 mg/kg) the same day showed a higher proportion of neutrophils in BALF (35 ± 7% vs 1.3 ± 0.8%), with earlier regenerative anaemia than with CARB-PTX-IV alone. A first strategy of CARB-PTX-IV dose reduction by 25% also induced neutrophil recruitment, but in a lower proportion than with the first combination (20 ± 6% vs 0.3 ± 0.3%) and avoiding regenerative anaemia. A second strategy of delaying CIS-DPI-ET and CARB-PTX-IV administrations by 24 h avoided both the recruitment of neutrophils in BALF and regenerative anaemia. Moreover, all these groups showed higher cytotoxicity (LDH activity, protein content) with no higher renal toxicities. These two strategies seem interesting to be assessed in terms of antitumor efficacy in mice.

Pulmonary and renal tolerance of cisplatin-based regimens combining intravenous and endotracheal routes for lung cancer treatment in mice.

Despite recent advances, platinum-based chemotherapy (partially composed of cisplatin, CIS) remains the backbone of non-small-cell lung cancer treatment. As CIS presents a cumulative and dose-limiting nephrotoxicity, it is currently administered with an interruption phase of 3-4 weeks between treatment cycles. During these periods, the patient recovers from the treatment side effects but so does the tumour. Our strategy is to increase the treatment frequency by delivering a cisplatin controlled-release dry powder for inhalation (CIS-DPI) formulation during these off-cycles to expose the tumour environment for longer to CIS, increasing its effectiveness. This is promising as long as the pulmonary and renal toxicities remain acceptable. The aim of the present investigation was to evaluate the pulmonary and renal tolerance of CIS-DPI (three times per cycle) and CIS using the intravenous (IV) route (CIS-IV) (one time per cycle) as monotherapies and to optimize their combination in terms of dose and schedule. At the maximum tolerated dose (MTD), combining CIS-DPI and CIS-IV impaired the pulmonary and the renal tolerance. Therefore, pulmonary tolerance was improved when the CIS-IV dose was decreased by 25% (to 1.5 mg/kg) while maintaining the MTD for CIS-DPI. In addition to this dose adjustment, a delay of 24 h between CIS-DPI and CIS-IV administrations limited the acute kidney injury.

[Experimental nephrology unit: overview and research projects]. / Unité de néphrologie expérimentale facultaire: etat des lieux et projets d'avenir.

After a short historical background of the Laboratory, the main research topics--renal toxicology, physiopathology of renal interstitial fibrosis and hormonology--are described in the perspective of a partnership between research clinicians and full time scientists. National as well as international scientific collaborations underline the need of combining expertises, stimulating also the training of youngest colleagues to the experimental approach of their future discipline.

Sodium nitroprusside inhibits glucose-induced insulin release by activating ATP-sensitive K+ channels.

Sodium nitroprusside (SNP) has been reported to be a potent stimulator of cGMP formation in different tissues, including pancreatic islets. The present study aimed at comparing the effects of sodium nitroprusside and dibutyryl cGMP on 86Rb outflow, 45Ca outflow, short-term 45Ca uptake, cytosolic Ca2+ concentration and insulin release from rat pancreatic islet cells. The data indicate that cGMP potentiates whilst SNP inhibits the glucose-induced insulin release. This inhibitory effect appears to be mediated by the activation of ATP-sensitive K+ channels leading to a decrease in Ca2+ influx and subsequent reduction in cytosolic free Ca2+ concentration. Whatever the exact mechanism(s) underlying the capacity of sodium nitroprusside to enhance the K+ permeability of the B-cell membrane, the drug appears to be an inadequate pharmacological tool to characterize the involvement of cGMP in the insulin secretory process. The experimental results also suggest that cGMP potentiates glucose-induced insulin release without affecting ionic movements.

Metabolic, cationic and secretory response to D-glucose in depolarized and Ca(2+)-deprived rat islets exposed to diazoxide.

D-glucose stimulates insulin release from islets exposed to both diazoxide, to activate ATP-responsive K+ channels, and a high concentration of K+, to cause depolarization of the B-cell plasma membrane. Under these conditions, the insulinotropic action of D-glucose is claimed to occur despite unaltered cytosolic Ca2+ concentration, but no information is so far available on the changes in Ca2+ fluxes possibly caused by the hexose. In the present experiments, we investigated the effect of D-glucose upon 45Ca efflux from islets exposed to both diazoxide and high K+ concentrations. In the presence of diazoxide and at normal extracellular Ca2+ concentration, D-glucose (16.7 mmol/l) inhibited insulin release at 5 mmol/l K+, but stimulated insulin release of 90 mmol/l K+. In both cases, the hexose inhibited 45Ca outflow. In the presence of diazoxide, but absence of Ca2+, D-glucose (8.3 to 25.0 mmol/l) first caused a rapid decrease in insulin output followed by a progressive increase in secretory rate. This phenomenon was observed both at 5 mmol/l or higher concentrations (30, 60 and 90 mmol/l) of extracellular K+. It coincided with a monophasic decrease in 45Ca efflux and either a transient (at 5 mmol/l K+) or sustained (at 90 mmol/l K+) decrease in overall cytosolic Ca2+ concentration. The decrease in 45Ca efflux could be due to inhibition of Na(+)-Ca2+ countertransport with resulting localized Ca2+ accumulation in the cell web of insulin-producing cells. A comparable process may be involved in the secretory response to D-glucose in islets exposed to diazoxide and a high concentration of K+ in the presence of extracellular Ca2+.

Recent developments in the chemistry of potassium channel activators: the cromakalim analogs.

Potassium channels play a crucial role in controlling the cell membrane potential. Among the different varieties of K(+) channels, the ATP-sensitive potassium channels (K(ATP) channels) have been characterized in numerous cell types, such as skeletal and smooth muscle cells, endocrine cells, cardiac cells and central neurons. Several molecules are known to activate K(ATP) channels and have been named "potassium channel openers" (PCOs). Such compounds may have a wide therapeutic potential and a few drugs are currently used as antihypertensive agents. Different chemical series of PCOs have been explored. This heterogeneous group of organic compounds comprises the benzopyran series including potent vasorelaxant drugs, such as cromakalim. The latter compound, a typical example of potassium channel opener, exerts its biological effect by activating K(ATP) channels. This review presents recent developments in the chemistry of cromakalim analoges and reports chemical aspects governing their potency and tissue selectivity.

Original 2-alkylamino-6-halogenoquinazolin-4(3H)-ones and K(ATP) channel activity.

A series of 6-substituted 2-alkylaminoquinazolin-4(3H)-ones structurally related to 3-alkylamino-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides were synthesized and tested as putative K(ATP) channel openers on isolated pancreatic endocrine tissue as well as on isolated vascular, intestinal, and uterine smooth muscle. Most of the 6-halogeno-2-alkylaminoquinazolin-4(3H)-ones were found to inhibit insulin release from pancreatic B-cells and to exhibit vasorelaxant properties. In contrast to their pyridothiadiazine dioxide isosteres previously described as more active on the endocrine than on the smooth muscle tissue, quinazolinones cannot be considered as tissue selective compounds. Biological investigations, including measurements of (86)Rb, (45)Ca efflux from pancreatic islet cells and measurements of vasodilator potency in rat aortic rings exposed to 30 or 80 mM KCl in the presence or the absence of glibenclamide, were carried out with 6-chloro- and 6-iodo-3-isopropylaminoquinazolin-4(3H)-ones. Such experiments showed that, depending on the tissue, these new compounds did not always express the pharmacological profile of pure K(ATP) channel openers. Analyzed by X-ray crystallography, one example of quinazolinones appeared to adopt a double conformation. This only suggests a partial analogy between the 2-alkylaminoquinazolin-4(3H)-ones and the 3-alkylamino-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides. In conclusion, the newly synthesized quinazolinones interfere with insulin secretion and smooth muscle contractile activity. Most of the compounds lack tissue selectivity, and further investigations are required to fully elucidate their mechanism(s) of action.

3-and 4-substituted 4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides as potassium channel openers: synthesis, pharmacological evaluation, and structure-activity relationships.

4-N-Substituted and -unsubstituted 3-alkyl- and 3-(alkylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides were synthesized and tested vs diazoxide and selected 3-alykl- and 3-(alkylamino)-7-chloro-4H-1,2,4-benzothiadiazine 1,1-dioxides as potassium channel openers on pancreatic and vascular tissues. Several 4-N-unsubstituted 3-(alkylamino)pyridothiadiazines and some 3-(alkylamino)-7-chlorobenzothiadiazines were found to be more potent than diazoxide for the inhibition of the insulin-releasing process. Moreover, the 3-(alkylamino)pyridothiadiazines appeared to be more selective for the pancreatic than for the vascular tissue. By means of the pharmacological results obtained on pancreatic B-cells, structure--activity relationships were deduced and a pharmacophoric model for the interaction of these drugs with their receptor site associated to the pancreatic K(ATP) channel was proposed. According to their selectivity for the B-cell (endocrine tissue) vs the vascular (smooth muscle tissue) ionic channel, selected 3-(alkylamino)-4H-pyrido[4,3-e]-1,2,4,-thiadiazine 1,1-dioxides may serve as pharmacological tools in studying the K(ATP) channels ("pancreatic-like" K(ATP) channels) in other tissues.

Synthesis and characterization of a quinolinonic compound activating ATP-sensitive K(+) channels in endocrine and smooth muscle tissues.

Original quinolinone derivatives structurally related to diazoxide were synthesized and their effects on insulin secretion from rat pancreatic islets and the contractile activity of rat aortic rings determined. A concentration-dependent decrease of insulin release was induced by 6-chloro-2-methylquinolin-4(1H)-one (HEI 713). The average IC(50) values were 16.9+/-0.8 microM for HEI 713 and 18.4+/-2.2 microM for diazoxide. HEI 713 increased the rate of (86)Rb outflow from perifused pancreatic islets. This effect persisted in the absence of external Ca(2+) but was inhibited by glibenclamide, a K(ATP) channel blocker. Inside-out patch-clamp experiments revealed that HEI 713 increased K(ATP) channel openings. HEI 713 decreased (45)Ca outflow, insulin output and cytosolic free Ca(2+) concentration in pancreatic islets and islet cells incubated in the presence of 16.7 or 20 mM glucose and extracellular Ca(2+). The drug did not affect the K(+)(50 mM)-induced increase in (45)Ca outflow. In aortic rings, the vasorelaxant effects of HEI 713, less potent than diazoxide, were sensitive to glibenclamide and to the extracellular K(+) concentration. The drug elicited a glibenclamide-sensitive increase in (86)Rb outflow from perifused rat aortic rings. Our data describe an original compound which inhibits insulin release with a similar potency to diazoxide but which has fewer vasorelaxant effects. Our results suggest that, in both aortic rings and islet tissue, the biological effects of HEI 713 mainly result from activation of K(ATP) channels ultimately leading to a decrease in Ca(2+) inflow.

A pyridothiadiazine (BPDZ 44) as a new and potent activator of ATP-sensitive K+ channels.

The present study was undertaken to characterize the effects of [3-(1',2'-dimethyl-propyl)amino-4H-pyrido[4,3-e][1,2,4]thiadiazine 1,1-dioxide] (BPDZ 44), a new pyridothiadiazine derivative, on ionic and secretory events in rat pancreatic islets. The drug increased the rate of 86Rb outflow regardless of the extracellular glucose concentration. The effects of BPDZ 44 on 86Rb outflow persisted in the absence of extracellular Ca2+ but were abolished by glibenclamide. BPDZ 44 markedly decreased 45Ca outflow and insulin output from islets perifused in the presence of 16.7 mM glucose and extracellular Ca2+. The drug did not affect the increase in 45Ca outflow mediated by K+ depolarization. Lastly, in single B-cells, BPDZ 44 inhibited the glucose but not the KCl-induced rise in cytosolic Ca2+ concentration ([Ca2+]i). These data suggest that BPDZ 44 inhibits the insulin releasing process by activating ATP-sensitive K+ channels. This K+ channel activation will lead to a decrease in Ca2+ influx and reduction in [Ca2+]i.

3-Morpholinosydnonimine as instigator of a glibenclamide-sensitive reduction in the insulin secretory rate.

The nitric oxide (NO) donor SIN-1 (3-morpholinosydnonimine) induced a concentration-dependent inhibition of the secretory response to glucose. The negative insulinotropic action of SIN-1 was attenuated by the hypoglycemic sulfonylurea glibenclamide. Moreover, the NO donor enhanced 86Rb outflow from perfused islets and reduced the glucose-induced increase in 45Ca outflow. The present data provide further evidence that NO donors impair the secretory response to glucose, at least in part, by activating the ATP-sensitive K+ channels.

RP 49356: inhibitory effects of ionic and secretory events in rat pancreatic islets.

Rp 49356, a 'K+ channel opener', inhibited 86Rb outflow, 45Ca outflow and insulin release from glucose-stimulated islets perifused in the presence of Ca2+. The drug lost its capacity to reduce 86Rb outflow in islets exposed to glucose-free or Ca(2+)-free medium. These observations suggest that RP 49356 might exhibit antagonistic actions on B-cell Ca2+ channels. This will, in turn, reduce glucose-stimulated insulin output and Ca(2+)-dependent 86Rb outflow.

Mechanical and ionic response of rat aorta to diazoxide.

Diazoxide provoked concentration-dependent and endothelium-independent relaxations of the mechanical responses evoked by low concentrations of KCl. Glibenclamide, tolbutamide and tetraethylammonium shifted the concentration-response curve for diazoxide to the right. The drug also caused a dose-dependent stimulation of 86Rb outflow which was inhibited by glibenclamide and tolbutamide. Diazoxide (10(-4) and 10(-3) M) inhibited the contractions elicited by 10(-1) M K+ and provoked a concentration-dependent reduction in the contractile responses to Ca2+. Diazoxide also reduced the KCl (8 x 10(-2) M)-induced increase in 45Ca outflow. These data indicate that the vasorelaxant properties of diazoxide are probably related to an inhibition of Ca2+ entry into smooth muscle cells. The reduction in Ca2+ entry appears to result from K+ channel activation. At high concentrations, diazoxide also exhibited antagonistic actions on voltage-sensitive Ca2+ channels.

Hydroxylamine, a nitric oxide donor, inhibits insulin release and activates K+ATP channels.

The present study was undertaken to assess the effects of hydroxylamine, a nitric oxide (NO) donor, on ionic and secretory events in rat pancreatic islets. Hydroxylamine provoked a concentration-dependent inhibition of the glucose-induced insulin release. This inhibitory action was counteracted by glibenclamide. Moreover, hydroxylamine increased the rate of 86Rb outflow from perifused islets. This effect persisted in the absence of external Ca2+ but was impaired by glibenclamide. Hydroxylamine decreased 45Ca outflow, [Ca2+]i and insulin output from islets exposed to 16.7 mM glucose and extracellular Ca2+. By contrast, hydroxylamine did not affect the increase in 45Ca outflow and [Ca2+]i evoked by K+ depolarization. These experimental results suggest that the negative insulinotropic action of the NO donor results, at least in part, from the activation of ATP-sensitive K+ channels leading to a decrease in Ca2+ influx and [Ca2+]i. Additional mechanisms, however, could also be involved in the NO donor modulation of the secretory process.

K+ channel openers and insulin release.

Recent in vivo and in vitro experiments suggested that the smooth muscle relaxation mediated by diverse pharmacologic agents resulted from K+ channel opening. Pinacidil, cromakalim, nicorandil, RP 49356, minoxidil sulfate and diazoxide belong to this new group of smooth muscle relaxants: the "K+ channel openers". Because modifications in the K+ permeability are known to represent a critical event in the insulin-releasing process, numerous studies have been performed in order to examine the putative effects of K+ channel openers on B-cell function. The aim of the present review is to summarize these experimental data which are sometimes divergent.

Inhibition of Na/Ca exchange stimulates insulin release from isolated rat pancreatic islets.

Na/Ca exchange was recently shown to regulate cytosolic free Ca2+ concentration ([Ca2+]i) in the pancreatic B-cell. The aim of the present study was to provide direct evidence that inhibition of the activity of the exchange may also increase insulin release. In the presence of extracellular Na+, caffeine stimulated 45Ca outflow but did not increase insulin release from islets perifused in the presence of 2.8 mM glucose. By contrast, in the absence of extracellular Na+, caffeine almost failed to increase 45Ca outflow and reversibly stimulated insulin release despite the fact that the absence of extracellular Na+ per se reduced basal insulin release. Similar findings were observed in islets perifused at a higher glucose concentration (8.3 mM) except that, in the presence of extracellular Na+, caffeine more markedly increased 45Ca outflow and stimulated insulin release. Our data provide direct evidence that inhibition of Na/Ca exchange with resulting blockade of Ca2+ outflow may increase insulin release from the pancreatic B-cell under suitable experimental conditions.

Effect on insulin release of compounds structurally related to the potassium-channel opener 7-chloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide (BPDZ 73): introduction of heteroatoms on the 3-alkylamino side chain of the benzothiadiazine 1,1-dioxide ring.

7-Chloro-3-pyridyl(alkyl)amino-4H-1,2,4-benzothiadiazine 1,1-dioxides and 3-alkylamino-7-chloro-4H-1,2,4-benzothiadiazine 1,1-dioxides containing one or more heteroatoms on the side chain in the 3 position have been synthesized in an attempt to discover new potent KATP-channel openers. The compounds were tested as putative pancreatic B-cells KATP channel openers by measuring their inhibitory activity on the insulin releasing process. The influence on the biological activity of the nature of the side chain in the 3 position is discussed.