High Receptor Occupancy Research Articles

A phase II study to evaluate the safety and efficacy of anlotinib combined with penpulimab for advanced refractory biliary tract cancer.

TPS582 Background: Although with modest efficacy, mFOLFOX is recommended as standard second-line chemotherapy for advanced biliary tract cancer (BTC). Several clinical trials are exploring the combination treatment of antiangiogenic drugs and immune checkpoint inhibitors. Anlotinib is an oral multi-targeted tyrosine kinase inhibitor targeting VEGFR1/2/3, FGFR1-4 and PDGFRα/β, which effectively blocks tumor neovascularization and growth. Previous phase I/II clinical trials suggested that anlotinib combined with PD-(L)1 inhibitors as second-line therapy was well tolerated and showed clinical anti-tumor activity in advanced biliary tract cancer (NCT03825705, NCT03996408, ChiCTR1900022003, ChiCTR2000037847). Penpulimab is a novel humanized anti-PD-1 IgG1 antibody with complete removal of Fc receptor mediated effect, and featuring slow antigen binding off-rate and high receptor occupancy. In this study, we explore anlotinib plus penpulimab as a chemo-free combination for second-line and above therapy. Methods: This is a prospective, single-arm, phase II study. BTC patients (pts) failed after the first-line treatment, aged 18-75 and an ECOG PS of 0-1 were recruited.Eligible pts received anlotinib (12mg, po, d1-14, q3w) and penpulimab (200mg, iv, d1, q3w) until disease progression, unacceptable toxicity or up to 2 years. The primary endpoint was Objective Response Rate (ORR). Secondary endpoints included Overall survival (OS), Progression-Free Survival (PFS), Disease Control Rate (DCR) and safety. Based on a two-sided test for one proportion with 5.0% type I error, 80% power to detect an improvement in ORR from 5% to 22%, there will be 27 pts enrolled considering 20% of pts dropping out. Clinical trial information: ChiCTR2300069126 .

An assessment of the effects of neurokinin1 receptor antagonism against nausea and vomiting: Relative efficacy, sites of action and lessons for future drug development.

A broad-spectrum anti-vomiting effect of neurokinin1 receptor antagonists (NK1 RA), shown in pre-clinical animal studies, has been supported by a more limited range of clinical studies in different indications. However, this review suggests that compared with vomiting, the self-reported sensation of nausea is less affected or possibly unaffected (depending on the stimulus) by NK1 receptor antagonism, a common finding for anti-emetics. The stimulus-independent effects of NK1 RAs against vomiting are explicable by actions within the central pattern generator (ventral brainstem) and the nucleus tractus solitarius (NTS; dorsal brainstem), with additional effects on vagal afferent activity for certain stimuli (e.g., highly emetogenic chemotherapy). The central pattern generator and NTS neurones are multifunctional so the notable lack of obvious effects of NK1 RAs on other reflexes mediated by the same neurones suggests that their anti-vomiting action is dependent on the activation state of the pathway leading to vomiting. Nausea requires activation of cerebral pathways by projection of information from the NTS. Although NK1 receptors are present in cerebral nuclei implicated in nausea, and imaging studies show very high receptor occupancy at clinically used doses, the variable or limited ability of NK1 RAs to inhibit nausea emphasizes: (i) our inadequate understanding of the mechanisms of nausea; and (ii) that classification of a drug as an anti-emetic may give a false impression of efficacy against nausea vs. vomiting. We discuss the potential mechanisms for the differential efficacy of NK1 RA and the implications for future development of drugs that can effectively treat nausea, an area of unmet clinical need.

Dosing Regimens of Immune Checkpoint Inhibitors: Attempts at Lower Dose, Less Frequency, Shorter Course.

Immune checkpoint inhibitors (ICIs) are a revolutionary breakthrough in the field of cancer by modulating patient’s own immune system to exert anti-tumor effects. The clinical application of ICIs is still in its infancy, and their dosing regimens need to be continuously adjusted. Pharmacokinetic/pharmacodynamic studies showed a significant plateau in the exposure-response curve, with high receptor occupancy and plasma concentrations achieved at low dose levels. Coupled with concerns about drug toxicity and heavy economic costs, there has been an ongoing quest to reevaluate the current ICI dosing regimens while preserving maximum clinical efficacy. Many clinical data showed remarkable anticancer effects with ICIs at the doses far below the approved regimens, indicating the possibility of dose reduction. Our review attempts to summarize the clinical evidence for ICIs regimens with lower-dose, less-frequency, shorter-course, and provide clues for further ICIs regimen optimization.

1-[2-(1-Cyclobutylpiperidin-4-yloxy)-6,7-dihydro-4H-thiazolo[5,4-c]pyridin-5-yl]propan-1-one: a Histamine H3 Receptor Inverse Agonist with Efficacy in Animal Models of Cognition.

A series of chemical optimizations, which was guided by in vitro affinity at histamine H3 receptor (H3 R), modulation of lipophilicity, ADME properties and preclinical efficacy resulted in the identification of 1-[2-(1-cyclobutylpiperidin-4-yloxy)-6,7-dihydro-4H-thiazolo[5,4-c]pyridin-5-yl]propan-1-one (45 e) as a potent and selective (Ki =4.0 nM) H3 R inverse agonist. Dipsogenia induced by (R)-α-methylhistamine was dose dependently antagonized by 45 e, confirming its functional antagonism at H3 R. It is devoid of hERG and phospholipidosis issues. Compound 45 e has adequate oral exposures and favorable half-life in both rats and dogs. It has demonstrated high receptor occupancy (ED80 =0.22 mg/kg) and robust efficacy in object recognition task and, dose dependently increased acetylcholine levels in brain. The sub-therapeutic doses of 45 e in combination with donepezil significantly increased acetylcholine levels. The potent affinity, selectivity, in vivo efficacy and drug like properties together with safety, warrant for further development of this molecule for potential treatment of cognitive disorders associated with Alzheimer's disease.

Motixafortide (BL-8040) and G-CSF Versus Placebo and G-CSF to Mobilize Hematopoietic Stem Cells for Autologous Stem Cell Transplantation in Patients with Multiple Myeloma: The Genesis Trial

Motixafortide (BL-8040) and G-CSF Versus Placebo and G-CSF to Mobilize Hematopoietic Stem Cells for Autologous Stem Cell Transplantation in Patients with Multiple Myeloma: The Genesis Trial

Abstract LB174: Discovery and preclinical characterization of INCA00186, a humanized monoclonal antibody antagonist of CD73, as a cancer immunotherapy

Abstract In the tumor microenvironment, dying cells release ATP which gets converted to AMP by CD39. AMP is subsequently converted to immunosuppressive adenosine by the extracellular 5'-nucleotidase CD73. CD73 is linked to the cell surface by a GPI-anchor and can be released into the plasma as soluble CD73. In order to lower extracellular levels and reverse the immunosuppressive activity of adenosine in the tumor microenvironment, an antibody was researched and discovered that antagonizes CD73 function. INCA00186 is a humanized monoclonal antibody that binds and inhibits CD73 function. INCA00186 binds human and cynomolgus CD73 with sub-nanomolar affinity, and inhibits CD73 enzymatic activity in a manner that is non-competitive for AMP binding. In functional studies, INCA00186 restored effector T cell proliferation in the presence of high concentrations of AMP. In the human A375 melanoma tumor model in CD34+ humanized NSG mice, INCA00186 decreased levels of cell surface CD73, displayed high receptor occupancy on tumor cells, and decreased CD73 activity in ex vivo assays of tumor homogenates. In the human MDA-MB-231 breast tumor model in CD34+ humanized NSG mice, INCA00186 decreased intratumoral adenosine concentrations. In combination with the novel A2A/A2B adenosine receptor antagonist INCB106385, INCA00186 synergistically restored effector T cell activity as measured by interferon gamma (IFNγ) production in the presence of high concentrations of AMP. In the human MDA-MB-231 breast tumor model in CD34+ humanized NSG mice, combination treatment with INCA00186 and INCB106385 controlled tumor growth significantly better than monotherapies. In summary, the data presented in this study demonstrates that INCA00186 is a potent CD73 antagonist and effectively attenuates adenosine induced immunosuppression in the tumor microenvironment. INCA00186 demonstrated anti-tumor immunity alone and, to a greater extent, in combination with the A2A/A2B adenosine receptor antagonist INCB106385. Citation Format: Shaun Stewart, Rebecca Buonpane, Jing Zhou, Michael Hansbury, Michael Smith, Hui Wang, Lu, Bin Su, Rahel Awdew, Cheng-Yen Huang, Ashwini Kulkarni, Shane Harvey, Arpita Mondal, Steve Wang, Christina Stevens, Michael Pratta, Elham Behshad, Alexandra Fanuka, Xiaodi Ren, Holly Koblish, Horacio Nastri, Patrick Mayes. Discovery and preclinical characterization of INCA00186, a humanized monoclonal antibody antagonist of CD73, as a cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB174.

Penpulimab plus anlotinib as second-line treatment for the small cell lung cancer after failure of platinum-based systemic chemotherapy.

8568 Background: Combined therapy of an immune checkpoint inhibitor with a targeted anti-angiogenic agent had been proved to be effective for lung cancer. Penpulimab (AK105) was engineered to eliminate FcγR binding and antibody-dependent cell-mediated cytotoxicity (ADCC)/ antibody-dependent celluar phagocytosis (ADCP) completely, where ADCC/ADCP effects could induce T-cell apoptosis and clearance and therefore compromise anti-tumor activity. Penpulimab demonstrated a slower programmed death-1(PD-1) antigen binding off-rate, which resulted in better cellular activity and higher receptor occupancy. Penpulimab also showed numerous contacts with N58 glycosylation on the BC loop of PD-1. These structural differentiations enhance the anti-tumor activity of penpulimab and improve its safety. Anlotinib is a multi-targeted tyrosine kinase inhibitor selective for VEGF receptors 1/2/3, FGF receptors 1-4, PDGF receptors α and β, and c-kit. Anlotinib has been approved by National Medical Products Administration as the treatment for small cell lung cancer (SCLC) patients, who had progressed/relapsed on or after at least two regimens of chemotherapy. Here we report the results of one cohort which received penpulimab plus anlotinib in a Phase II study. Methods: In Cohort 4 of an open-label, multi-center, multi-cohort Phase II study evaluating the efficacy and safety of penpulimab plus anlotinib in pts with advanced head, neck or chest tumors(NCT04203719), the SCLC patients, who failed to platinum-based systemic chemotherapy treatment, received penpulimab (200 mg IV Q3W) and anlotinib (12/10 mg PO 2 weeks on/1 week off). Primary endpoint was objective response rate (ORR) per RECIST v1.1. Secondary endpoints were disease control rate (DCR), duration of response, progression-free survival (PFS) and overall survival. Results: 20 patients (median age was 61 [range:37–75] years old, Eastern Cooperative Oncology Group performance status 0/1 [5%/95%], male/female [65%/35%]) were enrolled and received combination therapy (17 received 12 mg anlotinib, 3 received 10 mg anlotinib; and all received 200 mg penpulimab). At data cut-off (Jan 25, 2021), the confirmed ORR was 50.0% (10/20, 1 complete response and 9 partial response) and DCR was 75.0% (15/20). 9 PFS events (45%) had occurred, and the median PFS was 4.7 months (95% CI: 3.6-not reached). Grade 3 treatment-related adverse events (TRAEs) occurred in 30% (6/20, 2 hypertension, 1 hypertriglyceridaemia, 1 gamma-glutamyltransferase increased, 1 palmar-plantar erythrodysaesthesia syndrome and 1 hyponatraemia) of patients, No Grade 4 or 5 TRAEs had occurred. Conclusions: Penpulimab plus anlotinib showed favorable antitumor activity and an acceptable safety profile in SCLC patients who failed to platinum-based systemic chemotherapy. This new combination therapy warrants further evaluation for the treatment of SCLC. Clinical trial information: NCT04203719.

A phase II study of penpulimab, an anti-PD-1 antibody, in patients with relapsed or refractoryclassic Hodgkin lymphoma (cHL).

7529 Background: Penpulimab is a humanized IgG1 monoclonal antibody (mAb) that blocks PD-1 binding to PD-L1. Penpulimab, with its unique binding epitope, was engineered to eliminate Fc-mediated effector function that compromises anti-tumor immune cell function, and to optimize receptor occupancy by improving duration of drug binding. Fc-mediated effector functions, such as ADCC/ADCP, have been observed in most IgG4 anti-PD-1 mAbs but is absent in penpulimab, thereby potentially reducing the occurrence of immune-related adverse reactions. Penpulimab also demonstrated a slower PD-1 antigen binding off-rate than marketed anti-PD-1 mAbs, thereby resulting in better cellular activity and higher receptor occupancy. Penpulimab’s numerous contacts with N58 glycosylation on the BC loop of PD-1 may also contribute to a slower binding off-rate. These structural differentiations of penpulimab enhance its anti-tumor activity and produce a superior safety profile. Methods: AK105-201 is a multicenter, single-arm, open-label study of penpulimab in relapsed/refractory (R/R) cHL. All pts received penpulimab 200 mg Q2W until progression or unacceptable toxicity. Eligible pts had prior autologous stem cell transplant (ASCT) or at least 2 lines of prior chemotherapy. The primary endpoint was ORR based on the Lugano 2014 criteria as assessed by an independent review committee (IRC). Key secondary endpoints included CR rate, DCR, PFS, duration of response (DoR), safety, and tolerability. Results: As of 8 November 2020, of 94 pts (59.6% male, median age 32.0 yrs [31-71], 26.6% was ECOG 1) enrolled, 56 pts remained on treatment, 4 pts completed 24-months treatment and 25 had discontinued (17 due to disease progression, 3 due to AE). After a median follow-up of 15.8 months, the IRC-assessed ORR in the 85 pts evaluable for efficacy was 89.4% (95% CI: 80.8%, 95.0%). A total of 40 patients (47.1%) achieved CR. Median duration of response was not reached with range from 1.7 to 24.5+ months. Median PFS was not reached with 12-months PFS rate was 72.1% ( 95% CI: 60.5%, 80.8%). Treatment-related adverse events (TRAEs, with unlikely-related events included) occurred in 97.9% of pts ( ≥ G3 in 26.6% [25/94], treatment discontinuation in 5.3% [5/94]). Treatment-related SAEs occurred in 10.6%. Most frequent TRAEs (≥20%) were hypothyroidism (31.9%), upper respiratory tract infection (25.5%), fever (24.5%), and ALT elevations (23.4%). Grade ≥3 TRAEs reported in ≥2 pts were platelet count decreased (3.2%), hyperlipemia (3.2%), rash (3.2%), neutrophil count decreased (2.1%). Grade 3 immune-related AEs (irAEs) were reported in 4.3%: IgA nephropathy, pneumonitis, rash, psoriasis (each n = 1) and no G4 or G5 irAEs reported. Conclusions: Penpulimab was shown to be highly active in achieving in a CR rate of 47.1% in pts with R/R cHL while demonstrating lower rates of SAEs, TRAEs leading to discontinuation, and Grade ≥3 irAEs. Clinical trial information: NCT03722147.

Pharmacotherapy of schizophrenia: Mechanisms of antipsychotic accumulation, therapeutic action and failure

Schizophrenia is a multi-dimensional disorder with a complex and mostly unknown etiology, leading to a severe decline in life quality. Antipsychotic drugs (APDs) remain beneficial interventions in the treatment of the disorder, but vary significantly in binding profile, clinical effects and adverse reactions. The present review summarizes the main principles of APD mechanisms of action with a particular focus on recent findings in APD accumulation and its role in the therapeutic efficacy and treatment failure. High and low doses of APDs were shown to be effective in different dimensions of antipsychotic-like behaviour in rodent models. Efficacy of the APDs correlates with high dopamine D2 receptor occupancy, which occurs quickly after drug administration. However, onset and peak of action are delayed up to several days or weeks. APD accumulation via acidic trapping in synaptic vesicles is considered to underlie the time course of APD action. Use-dependent exocytosis, co-release with dopamine and serotonin and inhibition of ion channels impact on the neuronal transmission and determine effects of APDs. Disruption in accumulating properties leads to diminished APD effects. In addition, long-term APD administration at therapeutic doses leads to treatment failure both in animal models and in humans. APD failure was associated with treatment induced neuroadaptations, including a decline in extracellular dopamine levels, dopamine transporter upregulation, and altered neuronal firing. However, enhanced synaptic vesicle release has also been reported. APD loss of efficacy may be reversed through inhibition of the dopamine transporter or switching the administration regimen from continuous to intermittent. Thus, manipulating the accumulation properties of APDs, changes in the administration regimen and doses, or co-administration with dopamine transporter inhibitors may be considered to yield benefits in the development of new effective strategies in the treatment of schizophrenia.

Differential Binding of Sarilumab and Tocilizumab to IL-6Rα and Effects of Receptor Occupancy on Clinical Parameters.

We evaluated interleukin-6 (IL-6) receptor-α subunit (IL-6Rα) signaling inhibition with sarilumab and tocilizumab, the association between IL-6Rα receptor occupancy (RO) and C-reactive protein (CRP), and the potential clinical relevance of any differences. For this, we measured IL-6Rα binding and signaling inhibition with sarilumab and tocilizumab invitro, simulated soluble IL-6Rα RO over time for approved sarilumab subcutaneous (SC) and tocilizumab intravenous (IV) and SC doses, and assessed associations between calculated RO and CRP reduction, 28-joint Disease Activity Score based on CRP, and 20%/50%/70% improvement in American College of Rheumatology responses from clinical data. Sarilumab binds IL-6Rα in vitro with 15- to 22-fold higher affinity than tocilizumab, and inhibits IL-6-mediated classical and trans signaling via membrane-bound and soluble IL-6Rα. Sarilumab 200 and 150 mg SC every 2 weeks achieved >90% RO after first and second doses, respectively, maintained throughout the treatment period. At steady-state trough, RO was greater with sarilumab 200mg (98%) and 150 mg SC every 2 weeks (94%), and tocilizumab 162 mg SC weekly (>99%) and 8mg/kg IV every 4 weeks (99%), vs tocilizumab 162 mg SC every 2 weeks (84%) and 4 mg/kg IV every 4 weeks (60%). Higher RO was associated with greater CRP reduction and 28-joint Disease Activity Score based on CRP reduction, and more sarilumab patients achieving 20%/50%/70% improvement in American College of Rheumatology responses. The greatest reduction in CRP levels was observed with sarilumab (both doses) and tocilizumab 8mg/kg IV every 4 weeks (reductions proportionally smaller with 4mg/kg IV every 4 weeks). Higher IL-6Rα binding affinity translated into higher RO with sarilumab vs tocilizumab 4mg/kg every 4 weeks or 162 mg every 2 weeks; tocilizumab required the higher dose or increased frequency to maintain the same degree of RO and CRP reduction. Higher RO was associated with clinical parameter improvements.

Penpulimab (Anti-PD-1) combined with anlotinib as first-line therapy for unresectable hepatocellular carcinoma (uHCC): Updated results from a phase Ib/II study.

306 Background: Combined therapy of an immune checkpoint inhibitor with a targeted antiangiogenic agent had been proved to be effective for the treatment of uHCC. Penpulimab was engineered to eliminate FcγR binding and ADCC/ADCP completely, where ADCC/ADCP effects could induce T-cell apoptosis and clearance and then compromise anti-tumor activity. Penpulimab demonstrated a slower PD-1 antigen binding off-rate, which resulted in better cellular activity and higher receptor occupancy. Penpulimab also showed numerous contacts with N58 glycosylation on the BC loop of PD-1 which could be an advantage to facilitate interaction of PD-1 antibody and might contribute to slower binding off-rate. These structural differentiations offer more robust biological effect and enhance anti-tumor activity of penpulimab. Anlotinib is a multi-targeted tyrosine kinase inhibitor selective for VEGF receptors 1/2/3, FGF receptors 1-4, PDGF receptors α and β, and c-kit. Methods: In this open-label, multicenter phase Ib/II study, patients (pts) without prior systemic treatment, and classified as BCLC stage B (not amenable for locoregional therapy) or C, Child-Pugh ≤7, and ECOG PS ≤ 1 received Penpulimab (200mg IV Q3W) and Anotinib (8 mg PO 2weeks on/1 week off). Primary endpoint was ORR (RECIST v1.1); secondary endpoints were safety, DCR, DoR, TTP, PFS and OS. Results: 31 pts (median age 56 years [23–74], ECOG 0/1 [64%/36%], BCLC B/C [23%/77%], HBV/HCV [61%/7%]) received combined therapy. As of August 31, 2020, median follow-up time was 11.9 mons (range 3.7-17.7). Median PFS was 7.6 mons with 6-mons PFS rate was 57.6% while median TTP was 8.5 mons with 6-mons TTP rate was 62.7%. Median overall survival had not been met and 6-mons OS rate was 93.2%. The ORR was 31.0% (9/29) and DCR was 82.8% (24/29). At data cutoff, 77.8% of responders remained ongoing and still on treatment. Treatment-related adverse events (TRAEs) occurred in 90.3% of pts (≥G3 in 16.1% [5/31], no G5, treatment discontinuation in 9.7% [3/31]). Most common TRAEs (≥15%) were increased AST (38.7%) and ALT (35.5%), increased blood bilirubin (22.6%),asthenia (22.6%),decreased platelet count (19.4%) and rash (16.1%). Conclusions: Penpulimab plus Anlotinib showed favorable antitumor efficacy and an acceptable safety profile in pts with uHCC. The further randomized, phase 3 study of Penpulimab in combination with Anlotinib at a higher dose (10 mg PO 2 weeks on/1 week off) in this setting is ongoing (NCT04344158).

Language disturbances in schizophrenia: the relation with antipsychotic medication

Language disturbances are key aberrations in schizophrenia. Little is known about the influence of antipsychotic medication on these symptoms. Using computational language methods, this study evaluated the impact of high versus low dopamine D2 receptor (D2R) occupancy antipsychotics on language disturbances in 41 patients with schizophrenia, relative to 40 healthy controls. Patients with high versus low D2R occupancy antipsychotics differed by total number of words and type-token ratio, suggesting medication effects. Both patient groups differed from the healthy controls on percentage of time speaking and clauses per utterance, suggesting illness effects. Overall, more severe negative language disturbances (i.e. slower articulation rate, increased pausing, and shorter utterances) were seen in the patients that used high D2R occupancy antipsychotics, while less prominent disturbances were seen in low D2R occupancy patients. Language analyses successfully predicted drug type (sensitivity = 80.0%, specificity = 76.5%). Several language disturbances were more related to drug type and dose, than to other psychotic symptoms, suggesting that language disturbances may be aggravated by high D2R antipsychotics. This negative impact of high D2R occupancy drugs may have clinical implications, as impaired language production predicts functional outcome and degrades the quality of life.

<p>New Insights into the Mechanism of Action of Viloxazine: Serotonin and Norepinephrine Modulating Properties</p>

BackgroundViloxazine was historically described as a norepinephrine reuptake inhibitor (NRI). Since NRIs have previously demonstrated efficacy in attention deficit/hyperactivity disorder (ADHD), viloxazine underwent contemporary investigation in the treatment of ADHD. Its clinical and safety profile, however, was found to be distinct from other ADHD medications targeting norepinephrine reuptake. Considering the complexity of neuropsychiatric disorders, understanding the mechanism of action (MoA) is an important differentiating point between viloxazine and other ADHD medications and provides pharmacology-based rationale for physicians prescribing appropriate therapy.MethodsViloxazine was evaluated in a series of in vitro binding and functional assays. Its effect on neurotransmitter levels in the brain was evaluated using microdialysis in freely moving rats.ResultsWe report the effects of viloxazine on serotoninergic (5-HT) system. In vitro, viloxazine demonstrated antagonistic activity at 5-HT2B and agonistic activity at 5-HT2C receptors, along with predicted high receptor occupancy at clinical doses. In vivo, viloxazine increased extracellular 5-HT levels in the prefrontal cortex (PFC), a brain area implicated in ADHD. Viloxazine also exhibited moderate inhibitory effects on the norepinephrine transporter (NET) in vitro and in vivo, and elicited moderate activity at noradrenergic and dopaminergic systems.ConclusionViloxazine’s ability to increase 5-HT levels in the PFC and its agonistic and antagonistic effects on certain 5-HT receptor subtypes, which were previously shown to suppress hyperlocomotion in animals, indicate that 5-HT modulating activity of viloxazine is an important (if not the predominant) component of its MoA, complemented by moderate NET inhibition. Supported by clinical data, these findings suggest the updated psychopharmacological profile of viloxazine can be best explained by its action as a serotonin norepinephrine modulating agent (SNMA).

Pharmacological MRI responses of raclopride in rats: The relationship with D2 receptor occupancy and cataleptic behavior.

Pharmacological magnetic resonance imaging (phMRI) allows the visualization of brain pharmacological effects of drugs using functional MRI (fMRI). phMRI can help us facilitate central nervous system (CNS) drug development. However, there have been few studies demonstrating the dose relationship of the fMRI response induced by CNS drugs to underlying target engagement or behavioral efficacy. To clarify these relationships, we examined receptor occupancy measurements using positron emission tomography (PET) (n=3~5), fMRI (n=5~8) and a cataleptic behavior (n=6) with raclopride, a dopamine D2 receptor antagonist (8, 20, and 200μg/kg) on Wistar rats. Dopamine D2 receptor occupancy was increased dose dependently by raclopride (41.8±2.7%, 8μg/kg; 64.9±2.8%, 20μg/kg; 83.1±3.0%, 200μg/kg). phMRI study revealed significant positive responses to raclopride at 200μg/kg specifically in the striatum and nucleus accumbens, related to dopaminergic system. Slight fMRI responses were observed at 20μg/kg in some areas corresponding to the striatum and nucleus accumbens. There were no noticeable fMRI responses at 8μg/kg raclopride administration. Raclopride at 200μg/kg significantly increased the cataleptic score, although, at 8 and 20μg/kg, raclopride had no significant effects. These findings showed that raclopride-induced fMRI responses were observed at doses inducing cataleptic behavior and high D2 receptor occupancy, suggesting that phMRI can be useful for dose selection in clinical trial as an evaluation method of brain activity, which reflects behavioral responses induced by target engagements.

Clinical activity and safety of penpulimab (Anti-PD-1) with anlotinib as first-line therapy for advanced hepatocellular carcinoma (HCC).

4592 Background: Advanced HCC is a deadly disease with few systemic therapeutic options. VEGF blockade potentiates the effect of PD-1 inhibition by opposing the immunosuppressive effects of VEGF-A (increased DC maturation, enhanced T-cell infiltration, reduced MDSCs and Tregs in tumors). A sBLA has been submitted for an anti-PD-L1 + anti-VEGF combination as 1L treatment for advanced HCC. Penpulimab is a novel humanized anti-PD-1 IgG1 antibody with complete removal of Fc receptor mediated effect, and featuring slow antigen binding off-rate and high receptor occupancy. Anlotinib is a multi-targeted tyrosine kinase inhibitor selective for VEGF receptors 1/2/3, FGF receptors 1-4, PDGF receptors α and β, and c-kit. Methods: In this open-label, multicenter phase Ib/II study, treatment-naive pts with advanced HCC received penpulimab 200mg Q3W in combination with anlotinib 8mg QD (2 weeks on 1 week off) until loss of clinical benefit or unacceptable toxicity. The primary objectives were to assess antitumor activity by ORR (RECIST v1.1). The secondary objectives were to assess antitumor activity by DCR, DoR, TTP, and to assess the safety and tolerability of the combination. Results: As of Jan 14, 2020, 31 pts (median age 56 years [23-74], male 81%, ECOG 0/1 [64%/36%], BCLC B/C [23%/77%], HBV/HCV [61%/7%]) received combined therapy (a median of 6 [1-15] doses). Treatment-related adverse events (TRAEs) occurred in 93.5% of pts (G3 in 9.7% [3/31], no G4, and leading to treatment discontinuation in 6.5% [2/31]). Most frequent TRAEs were increased AST (35.5%), increased ALT (29%), asthenia (22.6%), decreased platelet count (19.4%), increased blood bilirubin (19.4%), increased bilirubin conjugated (19.4%), and rash (16.1%). Of 25 evaluable pts (with the opportunity to be followed-up for ≥2 scans, 12 weeks), confirmed ORR was 24% (6/25) and DCR was 84% (21/25). Five responders remained in response with DoR ranging 1.4+ to 6.9+ months. Median TTP was not reached and 6m-TTP rate was 63% (95% CI: 38%, 81%). Conclusions: Penpulimab in combination with anlotinib had a manageable safety profile and encouraging antitumor activities in patients with advanced HCC. No unexpected AEs were identified beyond the established safety profile for each agent. Evaluation of penpulimab + anlotinib (10 mg QD) in a phase 3 study for 1L HCC is currently underway. Clinical trial information: NCT04172571 .

T205. LUMATEPERONE IN THE TREATMENT OF SCHIZOPHRENIA: EVALUATION OF EXTRAPYRAMIDAL AND MOTOR SYMPTOMS IN 4 LATE-PHASE CLINICAL TRIALS

BackgroundStandard of care (SOC) antipsychotics exhibit efficacy at high dopamine D2 receptor occupancy (60%-80%), which is associated with increased risk of extrapyramidal symptoms (EPS). Lumateperone (lumateperone tosylate, ITI-007) is a mechanistically novel antipsychotic that simultaneously modulates serotonin, dopamine, and glutamate neurotransmission. Efficacy of lumateperone 42 mg (ITI-007 60 mg) has been established in randomized placebo-controlled trials and, in contrast to other antipsychotics, occurs at low D2 receptor occupancy (40%). In controlled trials, lumateperone 42 mg was well tolerated with a favorable safety profile. An open-label long-term study of patients with stable symptoms of schizophrenia switched from SOC antipsychotics to lumateperone 42 mg further supported the safety and effectiveness of lumateperone treatment.This post hoc analysis evaluated the incidence of EPS across short- and long-term studies of lumateperone in patients with schizophrenia.MethodsEPS data were pooled from 3 short-term placebo-controlled studies of lumateperone 42 mg in patients with an acute exacerbation of schizophrenia (Studies 005, 301, and 302); 2 of the studies (Studies 005 and 302) had risperidone 4 mg as an active control. Data from the open-label 1-year trial (Study 303) in patients who were switched from SOC antipsychotics to lumateperone 42 mg were utilized to evaluate EPS risk with long-term treatment. EPS assessments included incidence and time to onset of EPS-related treatment-emergent adverse events (TEAEs). EPS assessment scales included the clinician-rated Abnormal Involuntary Movement Scale (AIMS), the Barnes Akathisia Rating Scale (BARS), and the Simpson Angus Scale (SAS). Patients without akathisia (BARS ≤2) or parkinsonism (SAS ≤3) at baseline were evaluated for the emergence of BARS-confirmed akathisia (BARS >2) and SAS-confirmed parkinsonism (SAS >3) during treatment.ResultsThe pooled short-term safety population comprised 1,073 patients (placebo, 412; lumateperone 42 mg, 406; risperidone 4 mg, 255). The long-term open-label safety population comprised 239 patients who completed 1 year of treatment. In the pooled controlled studies, rates of EPS-related TEAEs were less for lumateperone 42-mg (3.0%) and placebo patients (3.2%) than risperidone (6.3%) patients. The most common EPS-related TEAE with lumateperone was akathisia (2.0%), which occurred less often than with placebo (2.9%) or risperidone (4.7%). Mean time to onset of EPS-related TEAEs was higher for the lumateperone group (17 days) compared with risperidone (9 days), and similar to placebo (14 days). Benztropine use was similar in lumateperone (2.5%) and placebo groups (2.2%) and higher in the risperidone group (9.0%); propranolol use was similar across groups (2.4–3.4%). Change from baseline in AIMS, BARS, and SAS scores was similar across groups.Similar to short-term treatment, long-term treatment with lumateperone was associated with a low incidence of EPS-related TEAEs (0.8%). In patients switched from SOC treatment to lumateperone 42 mg, the mean time to onset of EPS was 38 days. Initiation rates of benztropine and propranolol were low in the long-term study (1.7% and 0.3%, respectively). There were no notable changes in AIMS, BARS, or SAS scores during the 1-year treatment. In patients without BARS-assessed akathisia at baseline, BARS-confirmed akathisia occurred in 0.3% of patients. In patients without SAS-assessed parkinsonism at baseline, no patients had SAS-confirmed incidences of parkinsonism.DiscussionThis post hoc analysis supports the favorable EPS profile of lumateperone 42 mg in both acute and long-term treatment of patients with schizophrenia.

Abstract 4135: Novel dual A2A A2B adenosine receptor antagonists for cancer immunotherapy: in vitro and in vivo characterization

Abstract Adenosine is important messenger molecule that is involved in signal transmission in central nervous, cardiovascular and immunological systems. The immunosuppressive role of adenosine attract attention of many researchers recently and reversal of that effect is addressed by several different approaches i.e.: inhibition of enzymes that are producing the adenosine in tumor microenvironment like CD39 and CD73 but also the antagonization of adenosine receptors mainly A2A and A2B subtypes. Here we present a novel series of unsurmountable, dual A2A/A2B antagonists that retain its nanomolar potency in tumor-like adenosine-rich environment. This advantageous profile comes mainly from long residence time in adenosine receptors which transfers into high receptor occupancy even after full clearance of the compound from plasma. We are demonstrating how our inhibitors restore adenosine depleted immune functionality in the series of functional in vitro assays in primary cells. This includes the cytokine release by activated CD4+ and CD8+ human T-lymphocytes (driven by A2A) and dendritic cells (driven by A2B). Most importantly presented compounds show improved in vivo pharmacological profile in comparison to adenosine inhibitors currently tested in clinical trials manifested by high inhibition of CREB phosphorylation in mouse model. Citation Format: Michal Galezowski, Paulina Węgrzyn, Aneta Bobowska, Katarzyna Dziedzic, Joanna Szeremeta-Spisak, Marcin Nowogrodzki, Grzegorz Satala, Alicja Obara, Iwona Lozinska-Raj, Marcelina Dudek, Anita Janiga, Jacek Reus, Marek Wronowski, Magdalena Zastawna, Grzegorz Statkiewicz, Maciej Rogacki, Magdalena Ziembik, Karolina Grycuk, Foteini Soukou, Kinga Michalik, Agnieszka Adamus, Karolina Wiatrowska, Natalia Lewandowska, Aniela Golas, Olga Haberkiewicz, Rod Porter, Krzysztof Brzozka, Mateusz Nowak. Novel dual A2A A2B adenosine receptor antagonists for cancer immunotherapy: in vitro and in vivo characterization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4135.

The Discovery of LML134, a Histamine H3 Receptor Inverse Agonist for the Clinical Treatment of Excessive Sleep Disorders.

Histamine H3 receptor (H3R) inverse agonists that have been in clinical trials for the treatment of excessive sleep disorders, have been plagued with insomnia as a mechanism-based side effect. We focused on the identification of compounds that achieve high receptor occupancy within a short time, followed by rapid disengagement from the receptor, a target profile that could provide therapeutic benefits without the undesired side effect of insomnia. This article describes the optimization work that led to the discovery of 1-(1-methyl-6-oxo-1,6-dihydropyridazin-3-yl)piperidin-4-yl 4-cyclobutylpiperazine-1-carboxylate (18 b, LML134).

D2 Dopamine Receptor G Protein-Biased Partial Agonists Based on Cariprazine.

Functionally selective G protein-coupled receptor ligands are valuable tools for deciphering the roles of downstream signaling pathways that potentially contribute to therapeutic effects versus side effects. Recently, we discovered both Gi/o-biased and β-arrestin2-biased D2 receptor agonists based on the Food and Drug Administration (FDA)-approved drug aripiprazole. In this work, based on another FDA-approved drug, cariprazine, we conducted a structure-functional selectivity relationship study and discovered compound 38 (MS1768) as a potent partial agonist that selectively activates the Gi/o pathway over β-arrestin2. Unlike the dual D2R/D3R partial agonist cariprazine, compound 38 showed selective agonist activity for D2R over D3R. In fact, compound 38 exhibited potent antagonism of dopamine-stimulated β-arrestin2 recruitment. In our docking studies, compound 38 directly interacts with S1935.42 on TM5 but has no interactions with extracellular loop 2, which appears to be in contrast to the binding poses of D2R β-arrestin2-biased ligands. In in vivo studies, compound 38 showed high D2R receptor occupancy in mice and effectively inhibited phencyclidine-induced hyperlocomotion.

Discovery and Development of N-[4-(1-Cyclobutylpiperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide Dihydrochloride (SUVN-G3031): A Novel, Potent, Selective, and Orally Active Histamine H3 Receptor Inverse Agonist with Robust Wake-Promoting Activity.

A series of chemical optimizations guided by in vitro affinity at a histamine H3 receptor (H3R), physicochemical properties, and pharmacokinetics in rats resulted in identification of N-[4-(1-cyclobutyl-piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide dihydrochloride (17v, SUVN-G3031) as a clinical candidate. Compound 17v is a potent (hH3R Ki = 8.73 nM) inverse agonist at H3R with selectivity over other 70 targets, Compound 17v has adequate oral exposures and favorable elimination half-lives both in rats and dogs. It demonstrated high receptor occupancy and marked wake-promoting effects with decreased rapid-eye-movement sleep in orexin-B saporin lesioned rats supporting its potential therapeutic utility in treating human sleep disorders. It had no effect on the locomotor activity at doses several fold higher than its efficacious dose. It is devoid of hERG and phospholipidosis issues. Phase-1 evaluation for safety, tolerability, and pharmacokinetics, and long-term safety studies in animals have been successfully completed without any concern for further development.