RG-12915

RG 12915: a potent 5-hydroxytryptamine-3 antagonist that is an orally effective inhibitor of cytotoxic drug-induced emesis in the ferret and dog

RG 12915 [4-[N-(1-azabicyclo[2.2.2.]octan-3-(S)-yl)]2-chloro-cis 5a-(S)-9a-(S)-5a,6,7,8,9,9a-hexahydrobenzofurancarboxamide hydrochloride] is a potent and effective agent against cisplatin-induced emesis in the ferret after i.v. or p.o. administration. This agent (p.o.) is also highly protective against cisplatin-induced emesis in the dog, as well as cyclophosphamide/doxorubicin-induced emesis in the ferret. When administered either p.o. or i.v., RG 12915 has a lower ED50 value (0.004 mg/kg) than GR 38032F, BRL 43694 and metoclopramide for attenuating cisplatin-induced emetic episodes in the ferret. It also has a long duration of action against cisplatin-induced emesis in the ferret. In contrast to metoclopramide, RG 12915 lacks significant antidopaminergic activity both in vitro [( 3H]spiroperidol displacement), as well as in vivo (apomorphine-induced emesis). In radioligand binding assays, RG 12915 is a potent and selective displacer of binding of 5-hydroxytryptamine (5-HT)3 binding sites (IC50 value = 0.16 nM), whereas failing to displace binding of ligands for the alpha-1, alpha-2 and beta adrenergic, 5-HT1 or 5-HT2 or cholinergic-muscarinic sites with IC50 values less than 1 microM. At a p.o. dose (1 mg/kg) in which RG 12915 is highly protective against cisplatin-induced emesis in the dog, RG 12915 has no significant gastroprokinetic activity in the same species. In summary, RG 12915 is a potent and p.o. effective agent against cytotoxic drug-induced emesis in animal models. The antiemetic potency of RG 12915 against cisplatin is unrelated to antidopaminergic or gastroprokinetic activity, but may be related to its affinity for 5-HT3 binding sites.

Dose-ranging antiemetic evaluation of the serotonin antagonist RG 12915 in patients receiving anticancer chemotherapy

Background: RG 12915 is a potent, selective 5-HT3 receptor antagonist with a biologic half-life of 11-20 hours. RG 12915 prevents cisplatin-induced emesis in ferrets at doses of 0.03 mg/kg. Animal toxicology studies permitted safe testing in humans at doses of up to 2.0 mg/kg. This dose-ranging trial of intravenous RG 12915 was performed to determine the optimal dosage and adverse effects and to observe for antiemetic effects in patients receiving anticancer chemotherapy.
Methods: Twenty-six patients receiving chemotherapy likely to cause vomiting received a single intravenous dose of RG 12915 at a rate of 3 ml/minute beginning 60 minutes before chemotherapy. Four dose levels were explored: 0.25, 0.50, 1.0, and 2.0 mg/kg.
Results: No dose-limiting toxicities were observed. All adverse effects were mild and transient and included discomfort at the infusion site, hyperglycemia, headache, serum aspartate transaminase (AST) and alanine transaminase (ALT) elevations, and sedation. Antiemetic efficacy was seen in patients receiving cisplatin at doses of greater than or equal to 100 mg/m2.
Conclusion: RG 12915 can be administered safely at the dose levels explored. Single intravenous doses of RG 12915 prevented or lessened emesis caused by chemotherapy, including cisplatin given at doses of greater than or equal to 100 mg/m2. RG 12915 warrants further testing. Of the doses tested, the 2.0 mg/kg dose is the most appropriate for further exploration.

Cataractogenesis in rats induced by in utero exposure to RG 12915, a 5-HT3 antagonist

RG 12915, a selective 5-HT3 antagonist developed for the treatment of emesis and nausea associated with cancer chemotherapy, was administered by gavage to four groups of pregnant rats from Gestation Day 6 to 17 at doses of 0, 1, 10, and 100 mg/kg/day, as part of a Segment II (developmental toxicity) study. The 100 mg/kg/day dose was maternally toxic as indicated by decreased body weight gain and food consumption during the treatment period. A portion of the rats were allowed to deliver and rear their litters and three pups from two litters in the 100 mg/kg/day group were observed to have lens opacities (visible to the naked eye) at weaning. At a later examination, when the offspring were approximately 4 months old, four additional animals from the same two litters had cataracts. A slight growth retardation was also observed postweaning in the offspring of the 100 mg/kg/day group. To confirm the lens findings and more precisely define the no-effect dose, another study was conducted in which pregnant rats were administered daily RG 12915 doses of 0, 10, 30, 60, or 100 mg/kg/day from Gestation Day 6 to 17. There was a dose-related decrement in maternal body weight gain during the treatment period in the 30, 60, and 100 mg/kg/day groups (12, 28, and 47%, respectively) compared to the control group. A treatment-related incidence of nuclear cataract was observed in the offspring of the 60 and 100 mg/kg/day groups (litter incidence 6 and 45%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Development and optimization of a high-throughput screening assay for in vitro anti-SARS-CoV-2 activity: Evaluation of 5676 Phase 1 Passed Structures

Although vaccines are currently used to control the coronavirus disease 2019 (COVID-19) pandemic, treatment options are urgently needed for those who cannot be vaccinated and for future outbreaks involving new severe acute respiratory syndrome coronavirus virus 2 (SARS-CoV-2) strains or coronaviruses not covered by current vaccines. Thus far, few existing antivirals are known to be effective against SARS-CoV-2 and clinically successful against COVID-19. As part of an immediate response to the COVID-19 pandemic, a high-throughput, high content imaging-based SARS-CoV-2 infection assay was developed in VeroE6 African green monkey kidney epithelial cells expressing a stable enhanced green fluorescent protein (VeroE6-eGFP cells) and was used to screen a library of 5676 compounds that passed Phase 1 clinical trials. Eight drugs (nelfinavir, RG-12915, itraconazole, chloroquine, hydroxychloroquine, sematilide, remdesivir, and doxorubicin) were identified as inhibitors of in vitro anti-SARS-CoV-2 activity in VeroE6-eGFP and/or Caco-2 cell lines. However, apart from remdesivir, toxicity and pharmacokinetic data did not support further clinical development of these compounds for COVID-19 treatment.