Modeling shows the NK3R antagonist, ACER-801, reduces treatment-induced vasomotor symptoms.

e13013 Background: Hot flashes or vasomotor symptoms (VMS) are a common side effect of hormone deprivation (HD) therapy. Up to 80 % of cancer patients treated with tamoxifen (antiestrogen treatment) or leuprolide (androgen deprivation) have VMS. In some cases, patients discontinue HD therapy due to VMS severity and lower quality of life; therefore, reducing VMS is critical for patient compliance. NK3 receptor (NK3R) antagonists have previously been shown to reduce VMS in postmenopausal women. ACER-801 is a candidate NK3R antagonist drug intended to alleviate VMS severity when used with HD therapy. We used Quantitative Systems Pharmacology (QSP) modeling to predict the likely efficacy of ACER-801 in patients on HD therapy and evaluate the potential of hepatic drug-drug interactions between ACER-801 and tamoxifen or leuprolide. Methods: The model is composed of KNDy neurons in the arcuate nucleus with NKB, dynorphin, and estradiol effects on KNDy neurons, HPG axis, sex hormones, and neuroendocrine feedback. ACER-801, tamoxifen, and leuprolide PK, PD, and hepatic metabolism are included in the model. The model was developed, qualified, and tested using literature data. A tamoxifen-treated postmenopausal female virtual patient (VP) and leuprolide-treated male VP were created based on typical patients included in clinical trials. VMS severity and frequency were estimated based on the level of NKB binding to NK3R. Results: In the male VP, simulated leuprolide administration induced hypertrophy of KNDy neurons and VMS over six months. Coadministration of ACER-801 with leuprolide reduced VMS frequency and severity to near 0 in short-term (5-week) simulations. Simulations predict ACER-801 will not alter leuprolide metabolism nor increase plasma testosterone concentrations. Tamoxifen treatment increased VMS by 15% in simulations with the postmenopausal VP. Coadministration of ACER-801 with tamoxifen in this VP reduced VMS by 75% compared to tamoxifen monotherapy. ACER-801 had minimal effects on plasma estradiol concentrations in the postmenopausal VP. Drug-drug interactions between ACER-801 and tamoxifen were dependent on the simulated bioavailability of ACER-801. Using current estimates of ACER-801 bioavailability in the model, the hepatic concentration of ACER-801 had limited effects on tamoxifen metabolism, which are not expected to necessitate dose adjustments. Conclusions: Using a QSP neurobiology model as a research tool enabled us to evaluate the efficacy of the NK3R antagonist, ACER-801, to treat HD therapy-induced VMS. Simulations show ACER-801 may be highly efficacious for the treatment of induced-VMS. The research provided estimates of DDI with ACER-801 and tamoxifen and what clinical experiments would be needed to confirm those estimates.

Randomized Controlled Trial of Neurokinin 3 Receptor Antagonist Fezolinetant for Treatment of Polycystic Ovary Syndrome

Context Polycystic ovary syndrome (PCOS), a highly prevalent endocrine disorder characterized by hyperandrogenism, is the leading cause of anovulatory infertility. Objective This proof-of-concept study evaluated clinical efficacy and safety of the neurokinin 3 (NK3) receptor antagonist fezolinetant in PCOS. Design This was a phase 2a, randomized, double-blind, placebo-controlled, multicenter study (EudraCT 2014-004409-34). Setting The study was conducted at 5 European clinical centers. Patients Women with PCOS participated in the study. Intervention Interventions included fezolinetant 60 or 180 mg/d or placebo for 12 weeks. Main Outcome Measure The primary efficacy endpoint was change in total testosterone. Gonadotropins, ovarian hormones, and safety/tolerability were also assessed. Results Seventy-three women were randomized, and 64 participants completed the study. Adjusted mean (SE) changes in total testosterone from baseline to week 12 for fezolinetant 180 and 60 mg/d were −0.80 (0.13) and −0.39 (0.12) nmol/L versus −0.05 (0.10) nmol/L with placebo (P<0.0001 and P<0.05, respectively). Adjusted mean (SE) changes from baseline in luteinizing hormone (LH) for fezolinetant 180 and 60 mg/d were −10.17 (1.28) and −8.21 (1.18) versus −3.16 (1.04) IU/L with placebo (P<0.0001 and P=0.0022); corresponding changes in follicle-stimulating hormone (FSH) were −1.46 (0.32) and −0.92 (0.30) versus −0.57 (0.26) IU/L (P=0.0336 and P=0.3770), underpinning a dose-dependent decrease in the LH-to-FSH ratio versus placebo (P<0.001). Circulating levels of progesterone and estradiol did not change significantly versus placebo (P>0.1). Fezolinetant was well tolerated. Conclusions Fezolinetant had a sustained effect to suppress hyperandrogenism and reduce the LH-to-FSH ra

SUN-LB58 Repeated Once-Daily Administration of the Non-Hormonal Neurokinin 1,3 Receptor Antagonist NT-814 Reduces LH, Estradiol and Progesterone in Healthy Women

Introduction: Uterine fibroids (UF) affect up to 25% of women and endometriosis (EM) 10% of women worldwide. An ideal therapy would lower estradiol concentrations to reduce hormonal drive to the endometrium and myometrium, but not to the levels which cause the hot flashes and bone loss associated with current treatments. A target estradiol range of 110-180 pmol/L has been proposed1. GnRH secretion is modulated by neurokinin B (NKB) acting at the NK3 receptor via hypothalamic neurons expressing kisspeptin, NKB & dynorphin (KNDy neurons). In addition, Substance P acting at the NK1 receptor may also stimulate reproductive hormone release. We hypothesised that NT-814, a dual NK1,3 receptor antagonist, would reduce GnRH release and hence LH, estradiol and progesterone levels in women. This preliminary clinical study in healthy pre-menopausal women evaluated this hypothesis. Methods: We undertook a randomized, single-blind, placebo-controlled study. 32 healthy women attended for 2 consecutive menstrual cycles. In each cycle blood samples were taken on days 3/4, 9/10, 15/16 and 21/22 to measure serum sex hormone concentrations. No treatment was given in cycle 1 (baseline). During cycle 2, participants received placebo or one of three doses of NT-814 once per day; 40mg, 80mg or 120mg (n=8 per group) for up to 21 days. Results: Compared to placebo, NT-814 reduced LH, estradiol and progesterone concentrations in a dose-related manner. The median changes in average LH (IU/L) during cycle 2 compared to cycle 1 were: placebo, 0.16; 40mg, -0.13; 80mg, -0.46; 120mg, -0.58. Median change in average estradiol (pmol/L) in cycle 2 was: placebo, -16.5; 40mg, -9.3; 80mg, -92.1; 120mg, -141.4. The median changes in progesterone (nmol/L) on day 21/22 in cycle 2 compared to cycle 1 were: placebo, 3.2; 40mg, 8.0; 80mg, -5.7; 120mg, -19.4. The reductions in estradiol and progesterone with 120 mg NT-814 were significant (p=0.038 & p=0.046, respectively). There were no clear changes in FSH concentrations. Of note, in women treated with 120mg NT-814, the average estradiol level reduced from 310.8 pmol/L in cycle 1 to 179.8 pmol/L in cycle 2. Cycle length was extended by at least 6 days in 5 of 8 women receiving the 120 mg dose. NT-814 was well tolerated; no participant experienced hot flashes during treatment. Conclusions: Once-daily administration of the non-hormonal NK1,3 receptor antagonist NT-814 reduced serum LH, estradiol and progesterone in healthy women in a dose-related manner without causing vasomotor symptoms. The 120 mg dose of NT-814 lowered estradiol levels to potentially ideal levels for UF and EM treatment. These preliminary data support further studies with NT-814 to establish its efficacy and safety in treating patients with these hormone driven disorders. References: 1Barbieri RL Am J Obstet Gynaecol 1992 166 740-5.

Effect of a Bicyclic Pyrimidine Derivative (KRP-103), a Novel Selective Tachykinin NK1 Receptor Antagonist, on Bladder Function in Guinea Pigs

We evaluated the pharmacological characteristics of KRP-103, chemically named as ((2-(4-acetylpiperazin-1-yl)-6-[3,5-bis(trifluorometheyl)-phenylmethyl]-4- (2-methylphenyl)-6,7,8,9-tetrahydro-5H-pyrimido[4,5-b][1,5]oxazocin-5-one), and its effects on lower urinary tract function in guinea pigs. In radioligand binding assay, KRP-103 showed higher selectivity for human NK1 receptor (hNK1R) than for human NK2 receptor (hNK2R) and human NK3 receptor (hNK3R) (Ki for hNK1R, hNK2R and hNK3R=0.126 nM, > 10 000 nM and > 10 000 nM). In distention-induced rhythmic bladder contractions (RBCs) in urethane-anesthetized guinea pigs, intravenous administration of KRP-103 dose-dependently increased the shutdown time of RBCs and slightly decreased the amplitude of RBCs (only about 20%). In acutely spinalized guinea pig cystometory, intraduodenal administration of KRP-103 dose-dependently increased the effective bladder capacity with a minimum effective dose of 1 mg/kg. Furthermore, to clarify the site of action of KRP-103, we evaluated the inhibitory effects of KRP-103 on bladder contractions induced by electrical stimulation (ES) of the central or peripheral cut end of the pelvic nerve (PN). KRP-103 inhibited the bladder contractions induced by ES of the central cut end of PN but not those induced by ES of the peripheral cut end of PN. These results indicate that KRP-103 enhances bladder storage function by inhibiting sensory transmission from the bladder at the level of spinal cord without affecting bladder efferent function, suggesting that KRP-103 may be a suitable therapeutic drug for treatment of overactive bladder.

Neurokinin B Receptor Antagonism in Women With Polycystic Ovary Syndrome: A Randomized, Placebo-Controlled Trial

Context: Polycystic ovary syndrome (PCOS), the most common endocrinopathy in women, is characterized by high secretion levels of LH and T. Currently, there is no treatment licensed specifically for PCOS. Objective: The objective of this study was to investigate whether a targeted therapy would decrease LH pulse frequency in women with PCOS, subsequently reducing serum LH and T concentrations and thereby presenting a novel therapeutic approach to the management of PCOS. Design: This study is a double-blind, double-dummy, placebo-controlled, phase 2 trial. Settings: University hospitals and private clinical research centers were included. Participants: Women with PCOS aged 18–45 years participated. Intervention: Intervention included AZD4901 (a specific neurokinin-3 [NK3] receptor antagonist) at a dose of 20, 40, or 80 mg/day or matching placebo for 28 days. Main Outcome Measure: Change from baseline in the area under the LH serum concentration–time curve over 8 hours (area under the curve) on day 7 relative to placebo was measured. Results: Of a total 67 randomized patients, 65 were evaluable. On day 7, the following baseline-adjusted changes relative to placebo were observed in patients receiving AZD4901 80 mg/day: 1) a reduction of 52.0% (95% confidence interval [CI], 29.6–67.3%) in LH area under the curve; 2) a reduction of 28.7% (95% CI, 13.9–40.9%) in total T concentration; and 3) a reduction of 3.55 LH pulses/8 hours (95% CI, 2.0–5.1) (all nominal P < .05). Conclusions: The NK3 receptor antagonist AZD4901 specifically reduced LH pulse frequency and subsequently serum LH and T concentrations, thus presenting NK3 receptor antagonism as a potential approach to treating the central neuroendocrine pathophysiology of PCOS.

Expression of Tachykinins and Tachykinin Receptors and Interaction with Kisspeptin in Human Granulosa and Cumulus Cells1

The neurokinin B/NK3 receptor (NK3R) and kisspeptin/kisspeptin receptor (KISS1R), two systems which are essential for reproduction, are coexpressed in human mural granulosa (MGC) and cumulus cells (CCs). However, little is known about the presence of other members of the tachykinin family in the human ovary. In the present study, we analyzed the expression of substance P (SP), hemokinin-1 (HK-1), NK1 receptor (NK1R), and NK2 receptor (NK2R) in MGCs and CCs collected from preovulatory follicles of oocyte donors at the time of oocyte retrieval. RT-PCR, quantitative RT-PCR, immunocytochemistry, and Western blotting were used to investigate the patterns of expression of tachykinin and tachykinin receptor mRNAs and proteins and the possible interaction between the tachykinin family and kisspeptin. Intracellular free Ca2+ levels ([Ca2+]i) in MGCs after exposure to SP or kisspeptin in the presence of SP were also measured. We found that SP, HK-1, the truncated NK1R isoform NK1R-Tr, and NK2R were all expressed in MGCs and CCs. NK1R-Tr mRNA and NK2R mRNA and protein levels were higher in MGCs than in CCs from the same patients. Treatment of cells with kisspeptin modulated the expression of HK-1, NK3R, and KISS1R mRNAs, whereas treatment with SP regulated kisspeptin mRNA levels and reduced the [Ca2+]i response produced by kisspeptin. These data demonstrate that the whole tachykinin system is expressed and acts in coordination with kisspeptin to regulate granulosa cell function in the human ovary.