Discovery and characterization of prolactin neutralizing monoclonal antibodies for the treatment of female-prevalent pain disorders.

Prolactin (PRL) has recently been demonstrated to elicit female-selective nociceptor sensitization and increase pain-like behaviors in female animals. Here we report the discovery and characterization of first-in-class, humanized PRL neutralizing monoclonal antibodies (PRL mAbs). We obtained two potent and selective PRL mAbs, PL 200,031 and PL 200,039. PL 200,031 was engineered as human IgG1 whereas PL 200,039 was reformatted as human IgG4. Both mAbs have sub-nanomolar affinity for human PRL (hPRL) and produce concentration-dependent and complete inhibition of hPRL signaling at the hPRL receptor (hPRLR). These two PRL mAbs are selective for hPRL as they do not inhibit other hPRLR agonists such as human growth hormone or placental lactogen. They also cross-react with non-human primate PRL but not with rodent PRL. Further, both mAbs show long clearance half-lives after intravenous administration in FcRn-humanized mice. Consistent with their isotypes, these mAbs only differ in binding affinities to Fcγ receptors, as expected by design. Finally, PL 200,019, the murine parental mAb of PL 200,031 and PL 200,039, fully blocked stress-induced and PRL-dependent pain behaviors in female PRL-humanized mice, thereby providing in vivo preclinical proof-of-efficacy for PRL mAbs in mechanisms relevant to pain in females.

Inhibiting Kiss1 Neurons With Kappa Opioid Receptor Agonists to Treat Polycystic Ovary Syndrome and Vasomotor Symptoms.

CONTEXT: Recent evidence suggests that vasomotor symptoms (VMS) or hot flashes in the postmenopausal reproductive state and polycystic ovary syndrome (PCOS) in the premenopausal reproductive state emanate from the hyperactivity of Kiss1 neurons in the hypothalamic infundibular/arcuate nucleus (KNDy neurons). OBJECTIVE: We demonstrate in 2 murine models simulating menopause and PCOS that a peripherally restricted kappa receptor agonist (PRKA) inhibits hyperactive KNDy neurons (accessible from outside the blood-brain barrier) and impedes their downstream effects. DESIGN: Case/control. SETTING: Academic medical center. PARTICIPANTS: Mice. INTERVENTIONS: Administration of peripherally restricted kappa receptor agonists and frequent blood sampling to determine hormone release and body temperature. MAIN OUTCOME MEASURES: LH pulse parameters and body temperature. RESULTS: First, chronic administration of a PRKA to bilaterally ovariectomized mice with experimentally induced hyperactivity of KNDy neurons reduces the animals' elevated body temperature, mean plasma LH level, and mean peak LH per pulse. Second, chronic administration of a PRKA to a murine model of PCOS, having elevated plasma testosterone levels and irregular ovarian cycles, suppresses circulating levels of LH and testosterone and restores normal ovarian cyclicity. CONCLUSION: The inhibition of kisspeptin neuronal activity by activation of kappa receptors shows promise as a novel therapeutic approach to treat both VMS and PCOS in humans.

Pharmacological Characterization of Apraglutide, a Novel Long-Acting Peptidic Glucagon-Like Peptide-2 Agonist, for the Treatment of Short Bowel Syndrome.

Glucagon-like peptide-2 (GLP-2) agonists have therapeutic potential in clinical indications in which the integrity or absorptive function of the intestinal mucosa is compromised, such as in short bowel syndrome (SBS). Native hGLP-2, a 33-amino acid peptide secreted from the small intestine, contributes to nutritional absorption but has a very short half-life because of enzymatic cleavage and renal clearance and thus is of limited therapeutic value. The GLP-2 analog teduglutide (Revestive/Gattex; Shire Inc.) has been approved for use in SBS since 2012 but has a once-daily injection regimen. Pharmacokinetic (PK) and pharmacodynamic studies confirm that apraglutide, a novel GLP-2 analog, has very low clearance, long elimination half-life, and high plasma protein binding compared with GLP-2 analogs teduglutide and glepaglutide. Apraglutide and teduglutide retain potency and selectivity at the GLP-2 receptor comparable to native hGLP-2, whereas glepaglutide was less potent and less selective. In rat intravenous PK studies, hGLP-2, teduglutide, glepaglutide, and apraglutide had clearances of 25, 9.9, 2.8, and 0.27 ml/kg per minute, respectively, and elimination half-lives of 6.4, 19, 16, and 159 minutes, respectively. The unique PK profile of apraglutide administered via intravenous and subcutaneous routes was confirmed in monkey and minipig and translated into significantly greater in vivo pharmacodynamic activity, measured as small intestinal growth in rats. Apraglutide showed greater intestinotrophic activity than the other peptides when administered at less-frequent dosing intervals because of its prolonged half-life. We postulate that apraglutide offers several advantages over existing GLP-2 analogs and is an excellent candidate for the treatment of gastrointestinal diseases, such as SBS. SIGNIFICANCE STATEMENT: Apraglutide is a potent and selective GLP-2 agonist with an extremely low clearance and prolonged elimination half-life, which differentiates it from teduglutide (the only approved GLP-2 agonist). The enhanced pharmacokinetics of apraglutide will benefit patients by enabling a reduced dosing frequency and removing the need for daily injections.

Discovery of Potent, Selective, and Short-Acting Peptidic V2 Receptor Agonists.

The vasopressin analogue desmopressin (desamino-d-arginine8 vasopressin, dDAVP, 1) is a potent vasopressin 2 (V2) receptor (V2R) agonist approved in many countries for the treatment of diabetes insipidus, primary nocturnal enuresis, nocturia, and coagulation disorders. Since 1 is primarily excreted via the kidneys, an age-related decline in kidney function leads to slower elimination, prolonged antidiuresis, and hyponatremia. In search of novel, potent, selective, and short-acting peptidic V2R agonists, we synthesized a series of C-terminally truncated analogues of [Val4]dDAVP, 2, modified in positions 2, 3, and 7 and/or at the disulfide bridge. The peptides were evaluated for in vitro potency at the human V2 receptor, selectivity versus the related receptors (human vasopressin 1a receptor, human vasopressin 1b receptor, and human oxytocin receptor), and pharmacokinetic profiles in rodents and other higher species. The truncated analogues show excellent potency at the V2R, increased systemic clearance, and shorter half-life in rats. Two compounds 19 (c(Bua-Cpa-Thi-Val-Asn-Cys)-Pro-Agm) and 38 (c(Bua-Cpa-Thi-Val-Asn-Cys)-Pro-d-Arg-NEt2) have been selected for clinical development for nocturia.

Synthesis and Pharmacological Characterization of Novel Glucagon-like Peptide-2 (GLP-2) Analogues with Low Systemic Clearance.

Glucagon-like peptide-2 receptor agonists have therapeutic potential for the treatment of intestinal diseases. The native hGLP-2, a 33 amino acid gastrointestinal peptide, is not a suitable clinical candidate, due to its very short half-life in humans. In search of GLP-2 receptor agonists with better pharmacokinetic characteristics, a series of GLP-2 analogues containing Gly substitution at position 2, norleucine in position 10, and hydrophobic substitutions in positions 11 and/or 16 was designed and synthesized. In vitro receptor potency at the human GLP-2, selectivity vs the human GLP-1 and GCG receptors, and PK profile in rats were determined for the new analogues. A number of compounds more potent at the hGLP-2R than the native hormone, showing excellent receptor selectivity and very low systemic clearance (CL) were discovered. Analogues 69 ([Gly(2),Nle(10),D-Thi(11),Phe(16)]hGLP-2-(1-30)-NH2), 72 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-OH), 73 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NH2), 81 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NHEt), and 85 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NH-((CH2)2O)4-(CH2)2-CONH2) displayed the desired profiles (EC50 (hGLP-2R) < 100 pM, CL in rat <0.3 mL/min/kg, selective vs hGLP-1R and hGCGR). Compound 73 (FE 203799) was selected as a candidate for clinical development.

New, potent, and selective peptidic oxytocin receptor agonists.

Mothers of preterm babies frequently have difficulty establishing or maintaining lactation, thought to be due to interference with the milk ejection reflex. Administration of exogenous oxytocin can produce alveolar contraction and adequate breast emptying resulting in establishment of successful lactation. The natural hormone oxytocin is not receptor-selective and may cause hyponatremia via V2 receptor mediated antidiuresis. We have designed a series of potent oxytocin analogues containing N-alkylglycines in position 7 with excellent selectivity versus the related V1a, V1b, and V2 vasopressin receptors and short half-life: agonists 31 ([2-ThiMeGly(7)]dOT), 47 (carba-6-[Phe(2),BuGly(7)]dOT), 55 (carba-6-[3-MeBzlGly(7)]dOT), and 57 (carba-1-[4-FBzlGly(7)]dOT) have EC50 values at hOTR < 0.1 nM, selectivity ratios versus related human vasopressin receptors of >2000, IC50 at hV1aR > 500 nM, and total clearance in rats in the range of 60-80 mL min(-1) kg(-1). Compound 57 (FE 202767) is currently in clinical development for the treatment of preterm mothers requiring lactation support.

The selective vasopressin type 1a receptor agonist selepressin (FE 202158) blocks vascular leak in ovine severe sepsis*.

OBJECTIVE: To determine if the selective vasopressin type 1a receptor agonist selepressin (FE 202158) is as effective as the mixed vasopressin type 1a receptor/vasopressin V2 receptor agonist vasopressor hormone arginine vasopressin when used as a titrated first-line vasopressor therapy in an ovine model of Pseudomonas aeruginosa pneumonia-induced severe sepsis. DESIGN: Prospective, randomized, controlled laboratory experiment. SETTING: University animal research facility. SUBJECTS: Forty-five chronically instrumented sheep. INTERVENTIONS: Sheep were anesthetized, insufflated with cooled cotton smoke via tracheostomy, and P. aeruginosa were instilled into their airways. They were then placed on assisted ventilation, awakened, and resuscitated with lactated Ringer's solution titrated to maintain hematocrit ± 3% from baseline levels. If, despite fluid management, mean arterial pressure fell by more than 10 mm Hg from baseline level, an additional continuous IV infusion of arginine vasopressin or selepressin was titrated to raise and maintain mean arterial pressure within no less than 10 mm Hg from baseline level. Effects of combination treatment of selepressin with the selective vasopressin V2 receptor agonist desmopressin were similarly investigated. MEASUREMENTS AND MAIN RESULTS: In septic sheep, MAP fell by ~30 mm Hg, systemic vascular resistance index decreased by ~50%, and ~7 L of fluid were retained over 24 hours; this fluid accumulation was partially reduced by arginine vasopressin and almost completely blocked by selepressin; and combined infusion of selepressin and desmopressin increased fluid accumulation to levels similar to arginine vasopressin treatment. CONCLUSIONS: Resuscitation with the selective vasopressin type 1a receptor agonist selepressin blocked vascular leak more effectively than the mixed vasopressin type 1a receptor/vasopressin V2 receptor agonist arginine vasopressin because of its lack of agonist activity at the vasopressin V2 receptor.

Unlike arginine vasopressin, the selective V1a receptor agonist FE 202158 does not cause procoagulant effects by releasing von Willebrand factor.

OBJECTIVE: To compare the effects on von Willebrand factor release of the mixed vasopressin type 1a and type 2 receptor agonist arginine vasopressin and the selective vasopressin type 1a receptor agonist FE 202158, [Phe2,Ile3,Hgn4,Orn(iPr)8]vasopressin, at doses required for the treatment of septic shock. DESIGN: Prospective, randomized, controlled laboratory experiment. SETTING: University animal research facility. SUBJECTS: Twenty-four chronically instrumented sheep. INTERVENTIONS: After a 5-day recovery from instrumentation, sheep were randomly assigned to receive a single intravenous bolus of the selective vasopressin type 2 receptor agonist desmopressin (1 nmol·kg(-1)) or continuous intravenous infusions of arginine vasopressin (3 pmol·kg(-1)·min(-1)), the selective vasopressin type 1a receptor agonist FE 202158 (10 pmol·kg(-1)·min(-1)), or vehicle (0.9% NaCl) (n = 6 each). MEASUREMENTS AND MAIN RESULTS: The von Willebrand factor antigen activity relative to hemoglobin concentration (vWF:Ag/Hb ratio) was measured at different time points during the 120-min study period. Maximal vWF:Ag/Hb ratio expressed as percentage of baseline level was significantly increased compared to vehicle-infused animals (3 ± 2%) in the desmopressin (40 ± 6%, p < .001) and arginine vasopressin groups (25 ± 4%, p < .001). The ratio for the FE 202158 group was not statistically different from the sham group (9 ± 2%, p = .208). Notably, maximal vWF:Ag/Hb ratio was lower in the FE 202158 than the arginine vasopressin group (p < .005). CONCLUSIONS: Unlike the mixed vasopressin type 1a receptor/vasopressin type 2 receptor agonist arginine vasopressin, the selective vasopressin type 1a receptor agonist FE 202158 does not release von Willebrand factor. Because von Willebrand factor is involved in coagulatory and inflammatory pathways during septic shock, future studies should clarify the role of the vasopressin type 2 receptor-mediated von Willebrand factor increase by arginine vasopressin and the potential benefit of selective vasopressin type 1a receptor-agonists like FE 202158.

New, potent, selective, and short-acting peptidic V1a receptor agonists.

[Arg(8)]vasopressin (AVP) produces vasoconstriction via V(1a) receptor (V(1a)R)-mediated vascular smooth muscle cell contraction and is being used to increase blood pressure in septic shock, a form of vasodilatory hypotension. However, AVP also induces V(2) receptor (V(2)R)-mediated antidiuresis, vasodilation, and coagulation factor release, all deleterious in septic shock. The V(1a)R agonist terlipressin (H-Gly(3)[Lys(8)]VP) also lacks selectivity vs the V(2)R and has sizably longer duration of action than AVP, preventing rapid titration of its vasopressor effect in the clinic. We designed and synthesized new short acting V(1a)R selective analogues of general structure [Xaa(2),Ile(3),Yaa(4),Zaa(8)]VP. The most potent and selective compounds in in vitro functional assays (e.g., [Phe(2),Ile(3),Asn(Me(2))(4),Orn(8)]VP (31), [Phe(2),Ile(3),Asn((CH(2))(3)OH)(4),Orn(8)]VP (34), [Phe(2),Ile(3),Hgn(4),Orn(iPr)(8)]VP (45), [Phe(2),Ile(3),Asn(Et)(4),Dab(8)]VP (49), [Thi(2),Ile(3),Orn(iPr)(8)]VP (59), [Cha(2),Ile(3),Asn(4),Orn(iPr)(8)]VP (68)) were tested by intravenous bolus in rats for duration of vasopressive action. Analogues 31, 34, 45, and 49 were as short-acting as AVP. Compound 45, FE 202158, is currently undergoing clinical trials in septic shock.

Pharmacological characterization of FE 202158, a novel, potent, selective, and short-acting peptidic vasopressin V1a receptor full agonist for the treatment of vasodilatory hypotension.

FE 202158, ([Phe(2),Ile(3),Hgn(4),Orn(iPr)(8)]vasopressin, where Hgn is homoglutamine and iPr is isopropyl), a peptidic analog of the vasoconstrictor hormone [Arg(8)]vasopressin (AVP), was designed to be a potent, selective, and short-acting vasopressin type 1a receptor (V(1a)R) agonist. In functional reporter gene assays, FE 202158 was a potent and selective human V(1a)R agonist [EC(50) = 2.4 nM; selectivity ratio of 1:142:1107:440 versus human vasopressin type 1b receptor, vasopressin type 2 receptor (V(2)R), and oxytocin receptor, respectively] contrasting with AVP's lack of selectivity, especially versus the V(2)R (selectivity ratio of 1:18:0.2:92; human V(1a)R EC(50) = 0.24 nM). This activity and selectivity profile was confirmed in radioligand binding assays. FE 202158 was a potent vasoconstrictor in the isolated rat common iliac artery ex vivo (EC(50) = 3.6 nM versus 0.8 nM for AVP) and reduced rat ear skin blood flow after intravenous infusion in vivo (ED(50) = 4.0 versus 3.4 pmol/kg/min for AVP). The duration of its vasopressor effect by intravenous bolus in rats was as short as AVP at submaximally effective doses. FE 202158 had no V(2)R-mediated antidiuretic activity in rats by intravenous infusion at its ED(50) for reduction of ear skin blood flow, in contrast with the pronounced antidiuretic effect of AVP. Thus, FE 202158 seems suitable for treatment of conditions where V(1a)R activity is desirable but V(2)R activity is potentially deleterious, such as vasodilatory hypotension in septic shock. In addition to the desirable selectivity profile, its short-acting nature should allow dose titration with rapid onset and offset of action to optimize vasoconstriction efficacy and safety.

Novel D-amino acid tetrapeptides produce potent antinociception by selectively acting at peripheral kappa-opioid receptors.

Kappa-(kappa) opioid receptors are widely distributed in the periphery and activation results in antinociception; however supraspinal acting kappa-agonists result in unwanted side effects. Two novel, all d-amino acid, tetrapeptide kappa-opioid receptor agonists, FE 200665 and FE 200666, were identified and compared to brain penetrating (enadoline) and peripherally selective (asimadoline) kappa-agonists as potential analgesics lacking unwanted central nervous system (CNS) side effects. In vitro characterization was performed using radioligand binding and GTP gamma S binding. Antinociception was evaluated in both mice and rats. Rotarod tests were performed to determine motor impairment effects of the kappa-agonists. FE 200665 and FE 200666 showed high affinity for human kappa-opioid receptor 1 (Ki of 0.24 nM and 0.08 nM, respectively) and selectivity for human kappa-opioid receptor 1 (human kappa-opioid receptor 1/human mu-opioid receptor/human delta-opioid receptor selectivity ratios of 1/16,900/84,600 and 1/88,600/>1,250,000, respectively). Both compounds demonstrated agonist activity in the human kappa-opioid receptor 1 [35S]GTP gamma S binding assay (EC50 of 0.08 nM and 0.03 nM) and resulted in dose-related antinociception in the mouse writhing test (A50: 0.007 and 0.013 mg/kg, i.v., respectively). Markedly higher doses of FE 200665 and FE 200666 were required to induce centrally-mediated effects in the rotarod assay (548- and 182-fold higher doses, respectively), and antinociception determined in the mouse tail-flick assay (>1429- and 430-fold fold higher doses, respectively) after peripheral administration supporting a peripheral site of action. The potency ratios between central and peripheral activity suggest a therapeutic window significantly higher than previous kappa-agonists. Furthermore, FE 200665 has entered into clinical trials with great promise as a novel analgesic lacking unwanted side effects seen with current therapeutics.

Peripheral kappa-opioid agonists for visceral pain.

Kappa (kappa)-opioid receptor agonists are particularly effective analgesics in experimental models of visceral pain. Their analgesic effects are mediated in the periphery. The molecular targets involved include peripherally located kappa-receptors and possibly, at least for some nonpeptidic kappa-agonists, additional nonopioid molecular targets such as sodium channels located on primary sensory afferents. Overall, these properties are expected to be of therapeutic interest in various visceral pain conditions, including abdominal surgery associated with postoperative pain and ileus, pancreatitis pain, dysmenorrhea, labor pain and functional disorders such as irritable bowel syndrome or dyspepsia. The first kappa-agonists to be developed were brain-penetrating organic small molecules. Their development was eventually discontinued due to central side effects such as sedation and dysphoria attributed to kappa-receptors located behind the blood-brain barrier. New drug discovery programs are now geared towards the design of peripherally-selective kappa-agonists. So far, most of the organic molecule-based peripheral kappa-agonists have achieved limited peripheral selectivity and a practically insufficient therapeutic window to justify full development. These compounds have been used in a small number of clinical pilot studies involving visceral pain. Although encouraging, the clinical data available so far with this class of compounds are too limited and fragmented to fully validate the therapeutic utility of kappa-agonists in visceral pain. Additional clinical studies with safer kappa-agonists (i.e. with higher peripheral selectivity) are still required. The most suitable tools to address this question in the future appear to be the newly discovered class of tetrapeptide-based kappa-agonists, which have shown unprecedented levels of peripheral selectivity.

FE200041 (D-Phe-D-Phe-D-Nle-D-Arg-NH2): A peripheral efficacious kappa opioid agonist with unprecedented selectivity.

The side effects typically associated with the clinical profiles of opioid mu-receptor agonists have driven continuing efforts to identify novel efficacious analgesics, including agonists acting at opioid kappa receptors. Unfortunately, the therapeutic potential of kappa agonists seems limited by significant central nervous system side effects. Kappa opioid agonists, however, exhibit potent peripherally mediated antihyperalgesic and antinociceptive effects, suggesting that a peripherally acting kappa agonist may be efficacious in pain control with a more desirable safety profile than that associated with currently available opioids. Here, we report an all D-amino acid tetrapeptide characterized as a novel, highly selective kappa opioid receptor agonist. FE200041 (D-Phe-D-Phe-D-Nle-D-Arg-NH2) showed selectivity for the human kappa opioid receptor of greater than 30,000- and 68,000-fold versus human mu opioid receptor and human delta-opioid receptor receptors, respectively, and efficacious agonist activity using in vitro tissue assays. FE200041 produced local, peripheral antinociception in the hindpaw ipsilateral, but not contralateral, to injection. Antinociceptive effects of FE200041 in the mouse acetic acid writhing assay lasted over 60 min and were antagonized by naloxone and by selective kappa, but not mu, opioid receptor antagonists. FE200041 significantly inhibited acetic acid writhing and inhibited formalin-induced flinching in rats. FE200041 did not elicit sedation or motor impairment after systemic administration at a dose 10-fold higher than that needed to achieve antinociception. FE200041 is thus a potent peripherally restricted opioid kappa agonist with no demonstrable side effects typical of kappa agonists with central nervous system activity and with unprecedented selectivity for the opioid kappa receptor. The pharmacology of this compound suggests the possibility of therapeutic application.

Pharmacological profile of a new, potent, and long-acting gonadotropin-releasing hormone antagonist: degarelix.

We describe the pharmacological profile in rats and monkeys of degarelix (FE200486), a member of a new class of long-acting gonadotropin-releasing hormone (GnRH) antagonists. At single subcutaneous injections of 0.3 to 10 microg/kg in rats, degarelix produced a dose-dependent suppression of the pituitary-gonadal axis as revealed by the decrease in plasma luteinizing hormone (LH) and testosterone levels. Duration of LH suppression increased with the dose: in the rat, significant suppression of LH lasted 1, 2, and 7 days after a single subcutaneous injection of degarelix at 12.5, 50, or 200 microg/kg, respectively. Degarelix fully suppressed plasma LH and testosterone levels in the castrated and intact rats as well as in the ovariectomized rhesus monkey for more than 40 days after a single 2-mg/kg subcutaneous injection. In comparative experiments, degarelix showed a longer duration of action than the recently developed GnRH antagonists abarelix, ganirelix, cetrorelix, and azaline B. The in vivo mechanism of action of degarelix was consistent with competitive antagonism, and the prolonged action of degarelix was paralleled by continued presence of radioimmunoassayable degarelix in the general circulation. In contrast to cetrorelix and similarly to ganirelix and abarelix, degarelix had only weak histamine-releasing properties in vitro. These results demonstrate that the unique and favorable pharmacological properties of degarelix make it an ideal candidate for the management of sex steroid-dependent pathologies requiring long-term inhibition of the gonadotropic axis.