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Congenital hyperinsulinism (HI) is the most common cause of persistent hypoglycemia in neonates, infants, and children, and is caused by genetic mutations in the insulin secretion pathway in pancreatic beta-cells. Current medical and surgical treatments are often highly burdensome, only partially effective, and associated with significant morbidity. CRN04777 is a potent orally bioavailable SST5 agonist (EC50=0.41 nM) that is >1300 fold selective over other SST receptor subtypes. CRN04777 has been shown to suppress both glucose- and sulfonylurea (SU)-induced insulin secretion in rats. The latter is a model for the most common known monogenic form of human congenital HI. We report initial results from a randomized, double-blinded, placebo-controlled single ascending dose study evaluating the safety, pharmacokinetics and pharmacodynamics of CRN04777 in 74 healthy volunteers. Endogenous insulin secretion was stimulated using intravenous glucose tolerance tests (IVGTT) or SU challenges in separate cohorts of volunteers. In the IVGTT cohorts, single doses of CRN04777 (0.5-120 mg) were administered after an overnight fast and 1 hour prior to an IV bolus of 300 mg/kg glucose, followed by serial measurements of blood glucose and insulin over 180 minutes. The SU-challenge cohorts received single doses of CRN04777 (30 and 60 mg) one hour after SU administration (5 mg of glibenclamide/glyburide), followed by measurement of the IV glucose infusion rate (GIR) over 8 hours under automated euglycemic clamp conditions (ClampArt®). CRN04777 was orally absorbed (Tmax 1-3 hours) and demonstrated a dose dependent increase in systemic exposures with an apparent terminal elimination t1/2 of approximately 40 hours. Basal insulin secretion was reduced dose-dependently, with a 73% reduction following 120 mg of CRN04777. Likewise, glucose stimulated insulin secretion during the IVGTT (plasma insulin AUC) was reduced dose-dependently by approximately 50% with a parallel doubling of plasma glucose AUC following 120 mg of CRN04777. CRN04777 resulted in dose-dependent reversal of SU-induced insulin secretion, with 79% and 90% reductions in insulin AUC5-180min, respectively, at 30 and 60 mg doses. At the 60 mg dose of CRN04777, no exogenous glucose infusion was needed to prevent SU-induced hypoglycemia. CRN04777 was well tolerated across the dose range evaluated. All adverse events (AEs) were considered mild or moderate and there were no serious AEs. The data from this single-dose, proof-of-concept study show that the selective SST5 agonist CRN04777 is well tolerated after oral administration in healthy volunteers, is suitable for once daily dosing and suppresses insulin secretion under basal and stimulated conditions, including in a pharmacologic model of congenital HI. Multiple ascending dose evaluations in healthy volunteers are underway to support future studies in congenital HI patients. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Context Paltusotine is a once-daily, oral, nonpeptide small-molecule somatostatin receptor type 2 (SST2) agonist in clinical development for treatment of acromegaly. Objective This work aimed to evaluate change in insulin-like growth factor I (IGF-I) levels in patients switched from octreotide long-acting release or lanreotide depot monotherapy to paltusotine. Methods A phase 2, open-label, prospective, multicenter, multinational, nonrandomized, single-arm exploratory study was conducted in which dosage uptitrations were performed in a double-blinded manner. At 26 global sites, patients with acromegaly switched to paltusotine from injected somatostatin receptor ligand (SRL)-based therapy. Patients received 13-week treatment with once-daily oral paltusotine (10-40 mg/d). The primary end point was change from baseline to week 13 in IGF-I for patients who switched from long-acting octreotide or lanreotide depot monotherapy to paltusotine (group 1). All patients underwent a 4-week paltusotine washout at end of treatment period (wk 13-17). IGF-I, growth hormone (GH), patient-reported outcome, and safety data were collected. Results Forty-seven patients enrolled. In group 1 (n = 25), IGF-I and GH showed no significant change between SRL baseline and end of paltusotine treatment at week 13 (median change in IGF-I = −0.03×upper limit of normal [ULN]; P = .6285; GH = −0.05 ng/mL; P = .6285). IGF-I and GH rose significantly in the 4 weeks after withdrawing paltusotine (median change in IGF-I = 0.55×ULN; P < .0001 [median increase 39%]; GH = 0.72 ng/mL; P < .0001 [109.1% increase]). No patients discontinued because of adverse events (AE); no treatment-related serious AEs were reported. Conclusion These results suggest once-daily oral paltusotine was effective in maintaining IGF-I values in patients with acromegaly who switched from injected SRLs. Paltusotine was well tolerated with a safety profile consistent with other SRLs.

Purpose Evaluate the pharmacodynamics, pharmacokinetics, and safety of paltusotine, an orally bioavailable, nonpeptide, somatostatin receptor subtype 2 (SST2) agonist being developed for the treatment of acromegaly and neuroendocrine tumors. Methods A randomized, double-blind, placebo-controlled, single center, single and multiple ascending dose phase 1 study was conducted in healthy male volunteers who received (i) single-dose of oral paltusotine 1.25, 2.5, 5, 10, and 20 mg (solution); and 40 and 60 mg (capsules) or (ii) multiple-dose oral paltusotine capsules once daily 5 mg (× 7 days), 10, 20, and 30 mg (× 10 days). Main outcome measures were pharmacodynamics (changes in growth hormone-releasing hormone [GHRH] stimulated growth hormone [GH] and insulin-like growth factor 1 [IGF-1]), pharmacokinetics, safety, and tolerability. Results Single-dose cohorts: n = 41 active, n = 14 placebo. Multiple-dose cohorts: n = 24 active, n = 12 placebo. Paltusotine was well tolerated, orally bioavailable, associated with increased plasma concentrations to doses up to 40 mg, and was eliminated with a half-life of approximately 30 h. Single-dose paltusotine 1.25 to 20 mg suppressed GHRH-stimulated GH secretion by 44% to 93% compared to 15% with placebo. Multiple-dose paltusotine 5 to 30 mg administered once daily for 10 days suppressed IGF-1 by 19% to 37% compared to an increase of 2.4% with placebo. Conclusions Paltusotine suppresses GH and IGF-1 in a dose-dependent fashion, with a safety profile similar to currently approved SST2 receptor ligands. Paltusotine is a promising once-daily oral nonpeptide SST2 agonist candidate for managing acromegaly and neuroendocrine tumors. Trial registration NCT03276858, registered September 8, 2017, retrospectively registered.

Antipsychotic medications function by blocking postsynaptic dopaminergic signaling in the central nervous system. Dopamine transmission can also be modulated presynaptically by inhibitors of vesicular monoamine transporter 2 (VMAT2), which inhibit loading of dopamine into presynaptic vesicles. Here we investigated the combination of these mechanisms in animal models of schizophrenia and weight gain (a primary side effect of antipsychotics). When dosed alone, the highly selective VMAT2 inhibitor RRR-dihydrotetrabenazine (RRR-DHTBZ, also known as [+]

CRN04894 is a potent orally bioavailable MC2R (adrenal cortex specific ACTH receptor) antagonist (Kb=0.34 nM) that is >1000-fold selective for MC2R over other melanocortin receptor subtypes. In rats receiving continuous administration of ACTH via subcutaneously implanted osmotic pumps, oral administration of CRN04894 over 7 days has previously been shown to result in dose-dependent suppression of basal and ACTH stimulated corticosterone levels. This compound is in clinical development for the treatment of diseases of ACTH excess including congenital adrenal hyperplasia (CAH) and Cushing's Disease. We report initial results from a randomized double-blinded, placebo-controlled single ascending dose study evaluating the safety, pharmacokinetics and pharmacodynamics of CRN04894 in 39 healthy volunteers. After an overnight fast, single doses of CRN04894 were administered at approximately 8 am, 2 hours prior to an IV bolus of ACTH 1-24 (cosyntropin). Serial cortisol over 600 minutes and pharmacokinetics over 168 hours post CRN04894 dose were measured. Two different challenge doses of ACTH 1-24 were studied: 250 μg (supra-pharmacological) and 1 μg (comparable to ACTH concentrations encountered in CAH and Cushing's Disease). CRN04894 was rapidly orally absorbed (median tmax 0.5-1.5 hour), and demonstrated a dose dependent increase in systemic exposure, with an apparent terminal elimination t1/2 of approximately 20 hours. Unstimulated (basal) cortisol measured 2 hours after CRN04894 administration fell in a dose-dependent manner, resulting in reduction near the theoretical maximum with the 80 mg dose cohort (-56.1% [SEM 4.0%, n=12] vs +17.4% in placebo [SEM=18.1%, n=9]). Dose-dependent cortisol suppression following a supra-pharmacological ACTH-stimulated (250 μg) was also observed, with a 41% reduction in the area under the curve (AUC60-600min) post-stimulation at the 80 mg dose. Furthermore, a single dose of 80 mg of CRN04894 reduced the cortisol response (AUC15-120 min) to a disease relevant 1 μg ACTH challenge by 48%, maintaining cortisol concentrations within the normal range seen prior to dosing in a basal unstimulated state. Single doses of CRN04894 were well tolerated with no need for glucocorticoid supplementation. All adverse events (AEs) were considered mild or moderate and there were no serious AEs. The data from this single-dose, proof-of-concept study show that MC2R antagonist CRN04894 was well tolerated after oral delivery in healthy volunteers and demonstrated dose-dependent increases in exposure with lowering of basal and ACTH-stimulated cortisol secretion, including in the presence of disease relevant excess ACTH exposure. Multiple ascending dose evaluations are underway in anticipation of studies in patients with diseases of ACTH excess. Presentation: Sunday, June 12, 2022 11:15 a.m. - 11:30 a.m.

Adrenocorticotropic hormone (ACTH) is an important modulator of steroidal hormone synthesis and secretion from the adrenal gland and its selective activity at the melanocortin type 2 receptor (MC2) dictates the synthesis and secretion of cortisol (corticosterone in rats). Excess ACTH action contribute to the pathophysiology of Cushing’s disease (CD), ectopic ACTH secreting tumors (EAS), and Congenital Adrenal Hyperplasia (CAH). Cushing’s disease results from a microadenoma derived from pituitary corticotrophic cells that secretes excess ACTH, whereas EAS arises from nonpituitary ACTH secreting tumors. Excess ACTH action at the adrenal gland and resulting hypercortisolemia presents in a myriad of symptoms that result in high morbidity. CAH results from inactivating mutations in steroid synthesis pathways, resulting in lack of cortisol and aldosterone production. Lack of negative feedback by cortisol at the level of the pituitary causes the over-secretion of ACTH, and overproduction of adrenal androgens, causing significant virilization and reduction in quality of life. We hypothesize that blocking ACTH action directly via a selective MC2 receptor antagonist may provide an important new therapeutic mechanism for these patients. To test this hypothesis, Crinetics launched an iterative medicinal chemistry program to identify potent and selective nonpeptide ACTH antagonists with pharmaceutical and safety characteristics suitable for evaluation in human clinical trials. Unlike most other G protein coupled receptors, MC2 requires the presence of an accessory protein (MRAP) for cell surface expression and recognition of ACTH. Using CHO-K cells stably expressing this MC2-MRAP complex, iterative optimization led to the discovery of multiple chemical classes of highly potent, nonpeptide MC2 receptor selective antagonist leads, which were then further optimized for drug-like characteristics. We identified multiple compounds that exhibit high potency for human and rat MC2 receptors (hMC2 Kb

Cushing’s disease (CD) and Ectopic ACTH syndrome (EAS) stem from excess circulating adrenocorticotropic hormone (ACTH) and resulting hypercortisolemia. In CD, excess ACTH is secreted from pituitary tumors, whereas excess ACTH in EAS arises from nonpituitary tumors. ACTH acts on the adrenal melanocortin type 2 (MC2) receptor to control the synthesis and secretion of adrenal hormones, including the stress hormone cortisol (corticosterone in rats) which accounts for the comorbidities of CD and EAS. Availability of a potent ACTH antagonist that can normalize cortisol in patients with diseases of excess ACTH will be a major advance in endocrinology. Additionally, an ACTH antagonist will have utility in congenital adrenal hyperplasia (CAH) because of its ability to block production of excess adrenal androgens. Crinetics is evaluating and developing ACTH antagonists for the treatment of diseases of excess ACTH. To our knowledge, these compounds represent the first potent nonpeptide ACTH antagonists to demonstrate in vitro potency and in vivo efficacy. As a result, the direct effects of sustained MC2 receptor blockade on the structure and function of the adrenal gland have never been able to be assessed. We examined the effects of several orally bioavailable ACTH antagonists across a range of doses on Sprague-Dawley rat adrenal gland weight, histology, and hormone levels in repeat dosing (7-14 days) studies. Sustained MC2 receptor antagonism dose dependently blocked activity of ACTH at the level of the adrenal gland and reduced plasma corticosterone levels. In the normal rat, this resulted in dose-dependent atrophy of the adrenal gland as assessed by organ weights and microscopically. The atrophy was primarily observed in the cortisol producing zona fasciculata, as well as in the zona reticularis, with smaller reductions noted in the aldosterone producing zona glomerulosa. Additionally, hypertrophy of the adrenal glands caused by continuous subcutaneous administration of exogenous ACTH was reversed by treatment with an ACTH antagonist. The adrenal effects were accompanied by expected changes in corticosterone levels. These preclinical findings demonstrate the therapeutic potential of ACTH antagonism and provide a strong rationale for development of an orally bioavailable drug that can be used to combat CD, EAS, and CAH.

Injected depot formulations of somatostatin peptide analogs are routinely used to treat acromegaly and neuroendocrine tumors (NETs). CRN00808, a small molecule nonpeptide selective somatostatin receptor 2 (sst2) agonist, is being evaluated for efficacy and safety in patients with acromegaly. The current Phase 1 study was conducted in two Parts: In Part A, the absorption, metabolism, excretion, and mass balance of a single oral dose of 20 mg [14C]-CRN00808 (3.0 MBq) oral solution was characterized in six healthy male subjects. Plasma, blood, urine, and feces were collected for up to 432 hours, and were analyzed for total radioactivity and CRN00808 concentrations (plasma only). Metabolite profiling was conducted on the plasma, urine, and feces samples. In Part B, the absolute bioavailability of CRN00808 was determined by administering a single oral dose of 20 mg CRN00808 compared with a single micro-tracer intravenous (IV) bolus injection of 50 µg [14C]-CRN00808 (0.0185 MBq) in five healthy male subjects. The IV dose was administered approximately 90 minutes after the oral dose. Plasma samples were collected for up to 144 hours and were analyzed for total radioactivity and CRN00808 concentrations (plasma only). Key data from Part A and Part B will be presented. Available data from Part A of the study show that >90% of radioactivity was recovered within 7 days of dosing. The primary route of excretion was the feces (>90%) with minimal excretion in the urine (

Congenital hyperinsulinism (CHI) results from mutations within the insulin secretion pathway and is characterized by excessive and/or inappropriate insulin secretion by pancreatic islet β-cells. CHI is the most common cause of persistent hypoglycemia in newborns and infants and is estimated to affect 1:2500 to 1:50,000 live births. Prompt recognition and treatment are vital to prevent coma, long-term neurological complications, and even death. If medical control of CHI is unsuccessful, a near-total pancreatectomy may be required, but hypoglycemia often persists. The neuropeptide somatostatin is an important modulator of pancreatic hormonal signaling and activity at different somatostatin receptor (sst) subtypes dictates the suppression of insulin and/or glucagon. The injectable peptide drugs octreotide and lanreotide are potent sst2 agonists used to treat CHI, but in addition to suppressing insulin, the sst2 activity of these peptides may also inhibit glucagon secretion, potentially reducing effectiveness and compromising a key defense against hypoglycemia. Glucagon secretion from α-cells is inhibited through activation of sst2 receptors, while insulin secretion from β-cells is inhibited through activation of sst2 and sst5. We therefore hypothesize that agonists selectively targeting sst5 and lacking sst2 activity will offer an improved efficacy/safety profile for patients with hyperinsulinemic hypoglycemia. Using iterative medicinal chemistry and pharmacology, Crinetics has discovered several classes of highly potent, orally bioavailable, small molecule sst-subtype selective agonists with drug-like pharmaceutical properties. Our discovery efforts aimed at finding a compound to treat CHI have yielded potent and selective nonpeptide sst5 agonists with sub-nanomolar EC50s in cell-based assays of receptor activation. Insulin secretion from isolated human and rat islets was suppressed upon exposure to sst5 agonists. Potent and selective sst5 agonists were then evaluated in a number acute and repeat dose in vivo models (e.g., oGTT, fed/fasted conditions, sulfonylurea-induced hypoglycemia) to assess physiological effects and to gain mechanistic insights. As predicted by the in vitro pharmacology, selective nonpeptide sst5 agonists suppressed insulin secretion and raised blood glucose levels in each model, while having minimal effects on glucagon secretion. Leading sst5 agonists were also evaluated for drug like characteristics, including stability in liver microsomes, lack of inhibition of cytochromes P450 and the hERG ion channel, and were shown to exhibit good exposure upon oral dosing in both rats and dogs. The culmination of these studies has led to a subset of candidate molecules that are being evaluated in genotoxicity, safety pharmacology, and general toxicity studies to determine the molecule most suitable for evaluation in human clinical trials.

Patients with acromegaly not cured by surgery are often initially treated with injected peptide long-acting somatostatin receptor ligands (SRLs). Non-peptide small molecules can also activate the somatostatin receptor and do so with a high degree of precision for the target therapeutic receptor subtype. Paltusotine (formerly {"type":"entrez-protein","attrs":{"text":"CRN00808","term_id":"1048626668","term_text":"CRN00808"}}CRN00808) is a small molecule somatostatin type 2 (SST2) receptor agonist with high oral bioavailability (70%) and pharmacokinetic profile suitable for once daily dosing. In healthy volunteers, paltusotine has been shown to lower growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels. We hypothesized that patients with acromegaly could switch from injected SRLs to once daily oral paltusotine while maintaining baseline IGF-1 levels. ACROBAT Edge ({"type":"clinical-trial","attrs":{"text":"NCT03789656","term_id":"NCT03789656"}}NCT03789656) was a single-arm study designed to evaluate the safety and efficacy of switching from injected SRLs to paltusotine in patients with acromegaly. The primary analysis population consisted of those who had not achieved normal IGF-1 levels despite stable therapy with long-acting octreotide or lanreotide. Eligible patients received their last injection of SRL 4 weeks prior to switching to once daily oral paltusotine monotherapy for a 13-week treatment period. The starting dose of 10 mg per day was uptitrated in 10 mg increments at specified study visits to a maximal dose of 40 mg per day based on protocol specified study drug toleration and IGF-1 criteria. The primary endpoint was change in IGF-1 from baseline to the completion of the 13-week treatment period. Statistical testing was based on non-parametric Wilcoxon Sign Rank test of whether the median change is different from zero. In addition, the rise in IGF-1 during a 4-week washout period was used to provide supportive evidence of efficacy. Twenty-five patients were enrolled in the primary analysis group, three patients discontinued from the study for non-study drug related reasons, two during the treatment period and one during the washout period after completing treatment. The primary endpoint was achieved as paltusotine treatment resulted in no significant change in IGF-1 levels at week 13 compared to baseline [change in IGF-1 =-0.034 (-0.107, 0.107), median (IQR), p>0.6]. Of the 23 patients who completed the dosing period, 20 (87%) achieved IGF-1 levels at the end of treatment that were within 20% of baseline or lower. Median IGF-1 values rose significantly after paltusotine washout (p 10%) included: headache, arthralgia, fatigue, peripheral swelling, paresthesia and hyperhidrosis. There were no discontinuations due to adverse events and no treatment related serious adverse events. These results suggest that patients with acromegaly treated with injected SRLs can switch to oral paltusotine while maintaining IGF-1 and that paltusotine appeared to be well tolerated.

Injected depot formulations of somatostatin peptide analogs are routinely used to treat acromegaly and neuroendocrine tumors (NETs). CRN00808 is a small molecule nonpeptide selective somatostatin receptor 2 agonist whose safety, pharmacokinetics (PK), and pharmacodynamics (PD) has been characterized in preclinical studies. This study describes the final results from a first-in-human, single and multiple ascending dose Phase 1 study in healthy volunteers to measure the safety, PK, PD, and midazolam drug interaction potential of CRN00808 (NCT03276858; preliminary results with blinded safety data presented at ENDO 2018). In the single dose arm of the study, cohorts of 8 subjects (6 active: 2 placebo) received CRN00808 as an oral solution or capsules (1.25 mg to 60 mg, or placebo). The effect of food on CRN00808 PK was also evaluated. In the multiple dose arm, cohorts of 9 subjects (6 active: 3 placebo) received CRN00808 capsules once daily (5 mg to 30 mg, or placebo) for 7-10 days. In the drug-interaction arm, a single cohort of 8 subjects received 20 mg of CRN00808 for 7 days; midazolam PK was assessed before (Day -2) and after (Day 7) administration of CRN00808. Safety and PK were assessed in all phases of the study. Suppression of GHRH-induced GH secretion and suppression of serum IGF-1 were measured as PD endpoints in the single and multiple dose phases of the study, respectively. Once daily administration of 5-30 mg CRN00808 capsules exhibited dose-dependent increases in peak (Cmax) and total (AUC) plasma exposures. The apparent terminal elimination half-life was determined to be of 42-50 hours and steady state was achieved in 3-5 days. Capsules taken with a standard high fat, high calorie meal resulted in a markedly lower plasma CRN00808 AUC (83%). Oral administration of CRN00808 resulted in dose-dependent suppression of both GHRH stimulated GH and IGF-1 secretion; a single 10 mg dose was found to cause 91% suppression of GHRH-stimulated GH and 10 mg once per day for 10 days resulted in maximal suppression of serum IGF-1. Midazolam PK was unaffected by co-administration of 20 mg CRN00808, suggesting little or no risk of drug interaction with CYP3A4/5 substrates. Treatment emergent adverse events associated with CRN00808 were generally mild and transient, and consistent with those reported with other somatostatin agonists. In conclusion, results from this Phase I clinical trial in healthy volunteers support further clinical development of CRN00808 as a once-daily oral treatment of patients with acromegaly.

Cushing’s disease is most commonly the result of a microadenoma derived from pituitary corticotrophic cells that secretes excess adrenocorticotropic hormone (ACTH). ACTH is an important modulator of steroidal hormone synthesis and secretion from the adrenal gland and its selective activity at the melanocortin type 2 receptor (MC2) dictates the synthesis and secretion of cortisol (corticosterone in rats). The resulting hypercortisolemia in Cushing’s patients presents in a myriad of symptoms that include growth of fat pads, excessive sweating, dilation of capillaries, thinning of the skin, muscle weakness, hirsutism, depression/anxiety, hypertension, osteoporosis, insulin resistance, hyperglycemia, and heart disease, among others that result in high morbidity. We hypothesize that blocking ACTH action directly via a selective MC2 receptor antagonist may provide an important new therapeutic mechanism to help better manage Cushing’s disease in patients. To test this hypothesis, we launched an iterative medicinal chemistry program to identify potent and selective nonpeptide MC2 receptor antagonists with pharmaceutical and safety characteristics suitable for evaluation in human clinical trials. Unlike most other G protein coupled receptors, MC2 requires the presence of an accessory protein (MRAP) for cell surface expression and recognition of ACTH and our effort led to small molecule nonpeptides with antagonist activity in CHO-K cells stably expressing the MC2-MRAP complex. Iterative optimization led rapidly to the discovery of multiple chemical classes of highly potent, nonpeptide MC2 selective antagonist leads, which were then further optimized for drug-like characteristics. We have identified multiple compounds that exhibit high potency for human and rat MC2 receptors (hMC2 Kb

Congenital hyperinsulinism (CHI) results from mutations within the insulin secretion pathway and is characterized by excessive and/or inappropriate insulin secretion by pancreatic islet β-cells. CHI is the most common cause of persistent hypoglycemia in newborns and infants and is estimated to affect 1/30,000 to 1/50,000 live births. Prompt recognition and treatment are vital to prevent coma, long-term neurological complications, and even death. If medical control of CHI is unsuccessful, near-total pancreatectomy may be required. The neuropeptide somatostatin is an important modulator of pancreatic hormonal signaling and activity at different somatostatin receptor (sst) subtypes dictates the suppression of insulin and/or glucagon. Glucagon secretion from α-cells is inhibited through sst2 receptors and insulin secretion from β-cells is inhibited through activation of sst2, sst3, and sst5. The injectable peptide drugs octreotide and lanreotide are potent agonists at sst2 and are often deployed as the last medical intervention to prevent or delay pancreatectomy. These peptides’ sst2 activity leads to inhibition of glucagon secretion, potentially reducing their effectiveness and compromising a key defense mechanism against hypoglycemia. We hypothesize that agonists targeting sst5 but lacking sst2 activity will possess an optimal efficacy/safety profile for patients with hyperinsulinemic hypoglycemia. Using iterative medicinal chemistry, Crinetics has discovered several classes of highly potent, orally bioavailable, small molecule sst-subtype selective agonists with drug-like pharmaceutical properties. Our discovery efforts aimed at finding a compound to treat CHI have yielded potent and selective nonpeptide sst5 agonists with sub-nanomolar EC50s in cell-based assays of receptor activation. These compounds also typically possess similar potency for the rat sst5 receptor. To probe their physiological consequences and to gain mechanistic insights, we compared the acute and chronic effects of these agonists to the peptide pasireotide, a pan-sst agonist that is most potent at sst5, on glycemic control in several rat models, which generally demonstrate a high degree of translation to humans. These preclinical studies evaluated the effects of the sst5 agonists during oGTT, ipGTT, sulfonylurea-induced hypoglycemia, and on blood glucose levels in both the fed and fasted states. In each model, selective nonpeptide sst5 agonists suppressed insulin secretion and raised blood glucose levels while having minimal effects on glucagon secretion, as predicted by their in vitro pharmacology. These results support our efforts to develop potent nonpeptide selective sst5 agonists with pharmaceutical and safety profiles suitable for evaluation in human clinical trials.

CRN04894 is an orally administered nonpeptide that is a potent and selective antagonist for adrenocorticotropic hormone (ACTH) acting at the melanocortin 2 receptor (MC2R) and is currently under development for the treatment of diseases of ACTH excess such as Cushing’s disease, congenital adrenal hyperplasia, and ectopic ACTH-secreting tumors. Cushing’s disease results from an adenoma derived from pituitary corticotropic cells that secrete excess ACTH, whereas ectopic ACTH syndrome arises from nonpituitary ACTH secreting tumors. Congenital adrenal hyperplasia is a genetic disease that results in cortisol deficiency leading to high levels of ACTH and adrenal androgens. Each of these indications is characterized by high ACTH levels that act on MC2R expressed in the adrenal cortex to drive pathological elevations of adrenally derived steroid hormones. CRN04894 blocks the action of ACTH at MC2R, providing a potential novel treatment for these diseases. Preclinical models of chronic hypercortisolemia include implantation of ACTH-secreting pituitary tumor cells in mice and continuous administration of ACTH via subcutaneously implanted osmotic pumps in rats. These models induce features consistent with human diseases of ACTH excess including hypercortisolemia and hypertrophy of the adrenal glands. We employed both rodent models to examine the pharmacodynamic effects of CRN04894 on corticosterone levels and adrenal gland morphology. In the mouse pituitary tumor model, subcutaneous inoculation of the ACTH-secreting mouse pituitary tumor cell line, AtT-20, into immunodeficient mice resulted in formation of tumors and increased plasma ACTH and corticosterone levels. Repeated daily oral administration of CRN04894 for 14 days dose-dependently and robustly suppressed plasma corticosterone levels in mice with AtT-20 tumors. In the rat model, subcutaneous implantation of osmotic pumps delivering ACTH resulted in increased corticosterone levels, reduction in body weight, and hypertrophy of the adrenal glands after 7 days. Daily oral administration of CRN04894 over 7 days dose-dependently suppressed corticosterone levels, mitigated the effect of ACTH excess on body weight, and rescued the adrenal gland hypertrophy. These findings provide evidence that CRN04894 functions as an effective ACTH antagonist at MC2R to suppress adrenal corticosterone secretion in both mouse and rat models of ACTH excess and hypercortisolemia, thus providing a strong rationale for its potential therapeutic utility in diseases of ACTH excess. This work was supported in part by an SBIR grant from the NIH awarded to Dr. Struthers (R43- DK115245)

Depot injection formulations of peptide somatostatin receptor ligands (SRLs) are routinely used to treat acromegaly and neuroendocrine tumors (NETs). Paltusotine (CRN00808), an orally administered small molecule nonpeptide selective somatostatin receptor 2 (SST2) agonist has been shown to maintain GH and IGF-1 levels in acromegaly patients previously on depot SRLs (ACROBAT Edge NCT03789656). In this study, a capsule formulation was used, which did not exhibit dose proportional pharmacokinetics (PK) at doses >40 mg, required a 2-hour post-dose fast in overnight fasted patients, and had the potential for reduced bioavailability when taken with proton-pump inhibitors (PPI). A spray-dried dispersion (SDD) tablet formulation was developed with improved solubility in the physiological pH range and its performance was evaluated in healthy volunteers. Male and female healthy volunteers who met inclusion/exclusion criteria were enrolled in a single-center Phase 1 study (ANZCTR registration ACTRN12619001562167). A Cohort of 12 subjects was administered a single dose of paltusotine in a four-period cross-over design. Periods 1 and 2 assessed the effect of lansoprazole (a PPI) on PK of 20 mg dose of paltusotine SDD tablets. In Period 3, 20 mg dose of paltusotine SDD tablets was co-administered with a high fat, high-calorie meal. In Period 4, a 60 mg dose of paltusotine SDD tablets was administered to assess dose proportionality. In a separate cohort of subjects (n=12; also, a 4-period cross-over design), the relative bioavailability of capsules and SDD tablets was assessed, and the effect of food administration 0.5, 1, and 2 hour post-dose was evaluated. Subsequently, in another cohort of 12 subjects (a 3-period cross-over design), dose proportionality of the SDD tablets was evaluated at 40 mg and 80 mg dose with a 1-hour post-dose fast. A 4 hours post-dose fast was also assessed for the 80 mg dose. Pharmacokinetics and safety of paltusotine were evaluated. Paltusotine was generally well tolerated in this study. SDD tablets exhibited dose proportional increase in total systemic exposure (AUC) up to a dose of 80 mg. Healthy volunteers pretreated with the PPI, lansoprazole (15 mg bid for 3 days), and co-administered with paltusotine SDD tablets exhibited a small decrease (approximately 25%) in systemic exposure to paltusotine compared with the same subjects that had washed out from the PPI-pretreatment. SDD tablets exhibited significant reduction in systemic exposure when co-administered with a high-fat, high-calorie meal. However, the SDD formulation was less sensitive to timing of post-dose food administration compared to the capsule formulation. These data suggest that the SDD tablet formulation of paltusotine improves flexibility in dose administration, can be co-administered with PPIs and other agents that increase stomach pH, and reduces the post-dose fasting requirement.

Context: Treatment of 21-hydroxylase deficiency (21OHD) is difficult to optimize. Normalization of excessive ACTH and adrenal steroid production commonly requires supraphysiologic doses of glucocorticoids. Objectives: We evaluated the safety and tolerability of the selective corticotropin releasing factor type 1 (CRF1) receptor antagonist NBI-77860 in women with classic 21OHD and tested the hypothesis that CRF1 receptor blockade decreases early-morning ACTH and 17α-hydroxyprogesterone (17OHP) in these patients. Participants: The study enrolled eight classic 21OHD females, ages 18–58 years, seen at a single tertiary referral university setting. Design: This was a phase Ib, single-blind, placebo-controlled, fixed-sequence, single-dose trial. During three treatment periods separated by 3-week washout intervals, patients sequentially received placebo, NBI-77860 300 mg, and NBI-77860 600 mg at 10 pm; glucocorticoid therapy was withheld for 20 hours. We evaluated ACTH, 17OHP, androstenedione, and testosterone as well as NBI-77860 pharmacokinetics over 24 hours. Results: Dose-dependent reductions of ACTH and/or 17OHP were observed in six of eight subjects. Relative to placebo, NBI-77860 led to an ACTH and 17OHP reduction by a mean of 43% and 0.7% for the 300 mg dose, respectively, and by 41% and 27% for the 600 mg dose, respectively. Both NBI-77860 doses were well tolerated. Conclusion: The meaningful reductions in ACTH and 17OHP following NBI-77860 dosing in 21OHD patients demonstrate target engagement and proof of principle in this disorder. These promising data provide a rationale for additional investigations of CRF1 receptor antagonists added to physiologic doses of hydrocortisone and fludrocortisone acetate for the treatment of classic 21OHD.

Valbenazine (VBZ) is a vesicular monoamine transporter 2 (VMAT2) inhibitor approved for the treatment of tardive dyskinesia. The safety, tolerability and pharmacokinetics of VBZ following single and repeat once-daily (QD) dosing were evaluated in 2 randomized, single-center, double-blind studies in healthy male subjects. In the first study, 2 cohorts of 8 subjects were administered single doses (SD) of placebo (PBO; N = 2/period) or VBZ (N = 6/period; 1, 2, 5, or 12.5 mg for Cohort 1 and 12.5, 25, 50, or 75 mg for Cohort 2) using a sequential escalation scheme. The second study consisted of 2 phases. In the initial phase, subjects were administered SD PBO (N = 2/period) or VBZ (N = 6/period; 75, 100, 125 or 150 mg) with sequential escalation. In the second phase, subjects received PBO, or 50 or 100 mg VBZ (N = 4:8:8) QD for 8 days (Cohort 1) or PBO or 50 mg VBZ (N = 6:6) QD for 8 days (Cohort 2). For both studies, plasma concentrations of VBZ and its active metabolite, NBI-98782, were determined. Safety was assessed throughout the studies. PK parameters were determined using noncompartmental methods. In both studies, VBZ was rapidly absorbed with peak concentrations typically observed within 1.5 hours. Peak NBI-98782 concentrations were typically observed at 4.0 to 9.0 hours. Terminal elimination half-life for both VBZ and NBI-98782 was ~20 hours. Across the 1 to 150 mg SD range evaluated across the studies, VBZ and NBI-98782 Cmax and AUC increased dose-proportionally from 50 to 150 mg and more than dose-proportionally from 1 to 50 mg. QD VBZ and NBI-98782 Cmax and AUC parameters were also dose-proportional between the 50 and 100 mg doses. Steady-state for both analytes appeared to be achieved by Day 8. The accumulation index was ~1.5 for VBZ and ~2.5 for NBI-98782. Peak to trough fluctuation was approximately 250% for VBZ and 70% for NBI-98782. Across both studies, NBI-98782 exposure was approximately 20%–30% that of VBZ based on molar ratios. In the first study, the maximum-tolerated dose was not achieved; headache (2 events) was the only treatment-emergent adverse event (TEAE) reported by more than one subject. In the second study, fatigue (4 events) was the only TEAE reported by more than one subject following SD VBZ. Following QD VBZ, the TEAEs of fatigue, insomnia, disturbance in attention, and nervousness were dose-dependent; the latter three TEAEs were considered dose-limiting. Subject withdrawals due to TEAEs were 1 each for PBO and 50 mg VBZ QD, and 3 for 100 mg VBZ QD. Clinically relevant effects on laboratory parameters, vital signs or ECGs were limited to increased CPK (SD: 1 each for 5 mg VBZ and PBO), ALT (QD: 1 each for 50 and 100 mg VBZ and PBO), and triglycerides (QD: 1 each for 50 mg VBZ and PBO). VBZ has an acceptable safety profile and predictable pharmacokinetics that result in stable concentrations of active compounds with low peak-to-trough fluctuation following once-daily dosing.

Background Urocortin 2 and urocortin 3 are endogenous peptides with an emerging role in cardiovascular pathophysiology. We assessed their pharmacodynamic profile and examined the role of the endothelium in mediating their vasomotor effects in vivo in man. Methods and Results Eighteen healthy male volunteers (23±4 years) were recruited into a series of double‐blind, randomized crossover studies using bilateral forearm venous occlusion plethysmography during intra‐arterial urocortin 2 (3.6 to 120 pmol/min), urocortin 3 (1.2 to 36 nmol/min), and substance P (2 to 8 pmol/min) in the presence or absence of inhibitors of cyclooxygenase (aspirin), cytochrome P450 metabolites of arachidonic acid (fluconazole), and nitric oxide synthase (L‐ NMMA ). Urocortins 2 and 3 evoked arterial vasodilatation ( P NMMA reduced vasodilatation to substance P and urocortin 2 ( P ≤0.001 for both) but had little effect on urocortin 3 ( P >0.05). Neither aspirin nor fluconazole affected vasodilatation induced by any of the infusions ( P >0.05 for all). In the presence of all 3 inhibitors, urocortin 2– and urocortin 3–induced vasodilatation was attenuated ( P NMMA alone ( P ≤0.005). Conclusions Urocortins 2 and 3 cause potent and prolonged arterial vasodilatation without tachyphylaxis. These vasomotor responses are at least partly mediated by endothelial nitric oxide and cytochrome P450 metabolites of arachidonic acid. The role of urocortins 2 and 3 remains to be explored in the setting of human heart failure, but they have the potential to have major therapeutic benefits. Clinical Trial Registration http://www.clinicaltrials.gov/ /. Unique identifier: NCT01096706 and NCT01296607.