Casopitant: a new warrior in the antiemetic crusade

The Neurokinins: Peptidomimetic Ligand Design and Therapeutic Applications

The neurokinins are indisputably essential neurotransmitters in numerous pathoand physiological events. Being widely distributed in the Central Nervous System (CNS) and peripheral tissues, their discovery rapidly promoted them to drugs targets. As a necessity for molecular tools to understand the biological role of this class, endogenous peptides and their receptors prompted the scientific community to design ligands displaying either agonist and antagonist activity at the three main neurokinin receptors, called NK1, NK2 and NK3. Several strategies were implemented for this purpose. With a preference to small non-peptidic ligands, many research groups invested efforts in synthesizing and evaluating a wide range of scaffolds, but only the NK1 antagonist Aprepitant (EMENDT) and its prodrug Fosaprepitant (IVEMENDT) have been approved by the Food Drug Administration (FDA) for the treatment of Chemotherapy-Induced and Post-Operative Nausea and Vomiting (CINV and PONV, respectively). While non-peptidic drugs showed limitations, especially in side effect control, peptidic and pseudopeptidic compounds progressively regained attention. Various strategies were implemented to modulate affinity, selectivity and activity of the newly designed ligands. Replacement of canonical amino acids, incorporation of conformational constraints, and fusion with non-peptidic moieties gave rise to families of ligands displaying individual or dual NK1, NK2 and NK3 antagonism, that ultimately were combined with non-neurokinin ligands (such as opioids) to target enhanced biological impact.

Antiemetic efficacy of single-dose palonosetron and dexamethasone in patients receiving multiple cycles of multiple day-based chemotherapy

Introduction

The goal of pharmacological prophylaxis of chemotherapy-induced nausea and vomiting (CINV) should be the elimination of both nausea and vomiting symptoms during all planned chemotherapy cycles. The aim of this study was to assess the efficacy of a single dose of palonosetron and dexamethasone to prevent CINV and to guarantee an adequate food intake (FI) in patients receiving several cycles of multiple day-based chemotherapy (MD-CT).

Methods

Patients with advanced cancer but without a compromised nutritional status (bone mass index ≥ 18.5) were treated with 0.25 mg palonosetron plus 20 mg dexamethasone before MD-CT. The MD-CT regimen was either epirubicin plus ifosfamide or paclitaxel plus cisplatin and ifosfamide. Nausea, vomiting, and FI were monitored in a 7-day diary. Complete response (CR: no vomiting and no rescue therapy) was the primary endpoint, while complete control (CC: CR and no more than mild nausea) and the evaluation of FI were secondary endpoints. The endpoints were evaluated during the overall timescale (0–168 h) of the chemotherapy regimen.

Results

Fifty patients were enrolled, 80% of whom achieved CR and 78% achieved CC. During the six chemotherapy cycles, CR and CC ranged from 76% to 88% and from 62% to 88%, respectively. Moreover, patients with CR had a significantly (p < 0.0001) higher weekly food intake compared with patients not achieving CR.

Conclusions

This trial was the first to assess the efficacy of palonosetron and dexamethasone for the prevention of both nausea and vomiting in patients receiving multiple cycles of MD-CT. In this trial, the ability of patients to intake an adequate amount of food each week was correlated with nausea, thus providing clinicians with an objective parameter for the measurement of the effects of nausea. A single dose of palonosetron and dexamethasone was able to prevent CINV in most patients receiving 3 days of chemotherapy during all planned chemotherapy cycles.

The potential role for corticosterone in the induction of cleft palate in mice after treatment with a selective NK-1 receptor antagonist, casopitant (GW679769B)

BACKGROUND

Casopitant is a potent and selective NK-1 receptor antagonist that has shown clinical efficacy in the prevention of chemotherapy-induced and postoperative-induced nausea and vomiting.

METHODS

In an embryo-fetal development study, pregnant mice were given vehicle (sterile water) or doses of 30, 100, or 300 mg/kg/day casopitant on Gestation Day (GD) 6 to 15. Fetuses were evaluated for external, visceral, and skeletal abnormalities on GD 18. In a follow-on study to investigate casopitant-induced hormonal changes during the developmental period for palate formation, pregnant mice were given vehicle (sterile water) or 300 mg/kg/day casopitant once daily on GD 6 to 13. Blood was collected on GD 13 at various time-points for measurement of plasma adrenocorticotropic hormone and corticosterone (CRT) concentrations.

RESULTS

There was no evidence of developmental toxicity in mice at 30 or 100 mg/kg/day but 9% of fetuses at 300 mg/kg/day had cleft palate. Mice are sensitive to glucocorticoid-induced cleft palates, and NK-1 antagonists are known to modulate the hypothalamic-pituitary-adrenal axis leading to increases in corticosterone. On GD 13, mean plasma adrenocorticotropic hormone levels at 300 mg/kg/day were elevated by approximately twofold from vehicle-treated levels at 1 hr post-dose and mean plasma CRT levels were elevated by 3, 5, and 10-fold at 0.5, 1, and 2 hr post-dose, respectively.

CONCLUSIONS

The increased level of CRT was in the range previously shown in the literature to cause cleft palates in mice and was likely the underlying mechanism behind casopitant-induced cleft palate in mice.

Emerging drugs for insomnia: new frontiers for old and novel targets

BACKGROUND

Insomnia is the most prevalent sleep disorder, with up to 50% of the US adult population reporting symptoms of insomnia on a weekly basis and approximately 12% with insomnia disorder. Comorbid conditions such as depression and anxiety are frequent. Insomnia is more common with older age, female gender and socioeconomic status. Traditionally, therapy has focused on GABA(A) receptor agonists, and off-label antidepressant and antihistamine use.

OBJECTIVE

With increased understanding of complex neural networks involved in sleep and wake, hypnotics are being developed to target a broader variety of receptors with increasing selectivity. This review summarizes promising compounds in Phase II and III trials with evidence supporting efficacy for treatment of insomnia.

METHODS

5-HT(2A) and 5-HT(2C) antagonists, melatonergic (MT1/MT2) agonists, orexin receptor (OX1/OX2) antagonists, as well as GABA(A) receptor agonists are reviewed and summarized. Data are collected from PubMed and Pharmaprojects database searches, company websites, recent scientific meeting presentations and abstracts.

RESULTS/CONCLUSIONS

A variety of drugs targeting several pathways, including GABA(A) agonism, MT1/MT2 agonism, 5-HT(2A) antagonism, OX1/OX2 antagonism and others, are in Phase II and III trials. More work should be done to understand the impact of these drugs in certain populations and in the context of comorbid conditions.