Gastrin has been shown to be a growth stimulant in pancreatic cancer cells. Gastrazole is a potent and selective gastrin receptor antagonist. Two randomised blinded trials were conducted to assess the effect of gastrazole in advanced pancreatic cancer. Patients with biopsy-proven, inoperable pancreatic carcinoma were recruited. Trial A compared protracted venous infusion (PVI) gastrazole with PVI placebo, whereas trial B compared PVI gastrazole with PVI fluorouracil (5-FU). Eighteen patients were randomised in trial A. Gastrazole produced significantly better survival compared to placebo (median 7.9 months vs 4.5 months; 1-year survival: 33 vs 11%, respectively; log rank P ¼ 0.02). No difference in toxicity was seen between gastrazole and placebo, except central venous catheter and pump complications. Ninety-eight patients were randomised in trial B. No significant survival difference was detected between gastrazole and 5-FU (median: 3.6 vs 4.2 months; 1-year survival: 13.2 vs 26.2%, respectively; log rank P ¼ 0.42). Toxicity of gastrazole was mild with significantly less diarrhoea (P ¼ 0.03), stomatitis (Po0.001) and hand -foot syndrome (Po0.001) compared to 5-FU. Quality of life (QoL) assessment showed similar QoL between gastrazole and 5-FU at baseline and no significant differences occurred with treatment either between arms or within arms. Compared to placebo, patients with advanced pancreatic cancer treated with gastrazole appeared to live longer, albeit in a very small trial and will require confirmation with large-scale randomised data. However, it did not produce survival advantage over PVI 5-FU. Lack of toxicity for gastrazole may allow its combination with cytotoxic drugs.

8.70. 3 Overall, the data could be accounted for by assuming the variable expression of two receptor subtypes across the assays. The rat stomach appeared to express a single receptor characterized by a low affinity constant for L-365,260 (pKB-7.5). The guinea-pig gastric muscle and mouse stomach data could be explained by the presence of this receptor and a second one characterized by a high affinity constant for ). The activity of the two proposed receptor subtypes was consistent between experiments in the guinea-pig and the high affinity receptor appeared to be predominant. In contrast, the mouse stomach data could only be simulated by assuming that the proportion and absolute number of each subtype varied significantly between the replicate experiments. 4 The L-365,260 affinity estimates at the inferred receptor subtypes were indistinguishable from those obtained in a corresponding analysis of the behaviour of L-365,260 in CCKB/gastrin receptor radioligand binding experiments in guinea-pig gastric gland and mouse and rat cerebral cortex preparations.

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A 1,3,4-benzotriazepine was identified as a suitable lead in our effort toward obtaining a non-peptide parathyroid hormone-1 receptor (PTH1R) antagonist. A process of optimization afforded derivatives displaying nanomolar PTH1R affinity, a representative example of which behaved as a PTH1R antagonist in cell-based cyclic adenosine monophosphate (cAMP) assays, with selectivity over PTH2 receptors.

Starting from a novel, achiral 1,3,4-benzotriazepine-based CCK2 receptor antagonist, a process of optimization has afforded further compounds of this type that maintain the nanomolar affinity for recombinant, human CCK2 receptors and high selectivity over CCK1 receptors observed in the initial lead but display more potent inhibition of pentagastrin-stimulated gastric acid secretion in vivo. Moreover, this has largely been achieved without altering their potency at wild-type canine and rat receptors, as judged by their displacement of [125I]-BH-CCK-8S in a radioligand binding assay and by their activity in an isolated, perfused rat stomach bioassay, respectively. 2-(5-Cyclohexyl-1-(2-cyclopentyl-2-oxo-ethyl)-2-oxo-1,2-dihydro-3H-1,3,4-benzotriazepin-3-yl)-N-(3-(5-oxo-2,5-dihydro- [1,2,4]oxadiazol-3-yl)-phenyl)-acetamide (47) was identified as the most effective compound stemming from this approach, proving to be a potent inhibitor of pentagastrin-stimulated gastric acid secretion in rats and dogs by intravenous bolus as well as by enteral administration.