Discovery of LNP1892: A Precision Calcimimetic for the Treatment of Secondary Hyperparathyroidism

The calcium sensing receptor (CaSR) plays an important role in maintaining calcium homeostasis. The use of calcimimetic cinacalcet has been established to activate CaSR and normalize hypercalcemia. However, cinacalcet has limitations due to its high cLogP and pK_a. A systematic optimization of cinacalcet to reduce its cLogP and pK_a yielded compound 23a (LNP1892). Compound 23a showed excellent potency and a favorable pharmacokinetics profile, and lacked the liabilities of cinacalcet, making it a highly differentiated precision calcimimetic. In adenine-diet-induced chronic kidney disease (CKD) models, 23a demonstrated robust and dose-dependent efficacy, as measured by plasma parathyroid hormone (PTH) levels. It also showed an excellent safety profile in animal studies. Phase 1 clinical trials with 23a in healthy volunteers confirmed its excellent safety, tolerability, and effectiveness in lowering PTH levels in a dose-dependent manner, without causing symptomatic hypocalcaemia. Encouraged by these promising results, LNP1892 was taken to a Phase 2 study in CKD patients.

Lower injection-site reactions and long-term safety, immunogenicity, and efficacy of etanercept biosimilar YLB113: Results from a post-hoc analysis of a double-blind, randomized, phase III comparative study and its open-label extension in patients with rheumatoid arthritis

AIM

YLB113 biosimilar was evaluated in an open-label extension single-arm study to assess long-term safety, efficacy, and immunogenicity in patients with rheumatoid arthritis (RA). We also report post-hoc results on the incidence of injection-site reactions (ISRs) and injection-site erythema (ISE) from a phase III study.

METHOD

Participants from the phase III, double-blind, randomized, 96 week equivalence study who completed the final visit received 50 mg YLB113 subcutaneously every 2 weeks. Key safety end points were assessed through adverse events (AEs), ISRs, ISE, and anti-drug antibody (ADA) incidence. The efficacy end point was change from baseline in Disease Activity Score 28-joint count (DAS28) over time.

RESULTS

Of 201 participants, 184 (91.5%) completed the study. Treatment-emergent AEs were experienced by 93.5% and severe AEs by 10.0% of participants. The discontinuation rate due to AEs was 2.0%. Overall, 20.0% of participants reported an incidence of ISRs throughout the open-label extension study. Two participants developed ADAs, and none developed neutralizing ADAs at any time after study drug administration. The overall DAS28 (mean ± SD) change was 2.22 ± 0.95 at the study transition, 2.10 ± 0.91 at week 72, and 2.06 ± 0.89 at the end of the study. In the post-hoc analysis, YLB113 showed a statistically significant lower incidence of ISRs (10 [3.8%], P < 0.0001) and ISE (5 [1.9%], P < 0.0001) compared with the reference product Enbrel®.

CONCLUSION

YLB113 demonstrated long-term safety and sustained efficacy for up to 96 weeks. Patients on YLB113 experienced significantly lower ISRs and ISE in a post-hoc analysis of the phase III study when compared with reference product.

A prospective, randomized, parallel group, double blind, multicenter study to compare the efficacy, safety and immunogenicity of Lupin's Ranibizumab with Lucentis® in patients with neovascular age-related macular degeneration

Purpose:

The present study compares the efficacy, safety, and immunogenicity of Lupin’s biosimilar ranibizumab with that of Lucentis^® in patients with neovascular age-related macular degeneration.

Methods:

This prospective, double-blind, multi-centric phase-III study was conducted across 19 centers in India. A total of 202 patients with neovascular age-related macular degeneration were randomized (1:1) to receive either Lupin’s biosimilar ranibizumab or Lucentis^®, 0.5 mg, as an intravitreous injection once every month for 3 months. The primary efficacy endpoint was the proportion of patients who lost fewer than 15 letters from baseline in best-corrected visual acuity. The safety profile included assessment of adverse events, ophthalmic examination, physical and systemic examination, and vital parameters. The immunogenicity assessment was based on evaluation of anti-drug antibodies.

Results:

Overall, 174 patients (87 [86.14%] in each group) completed the study. The demographics and baseline characteristics were comparable between the treatment groups. The proportion of patients losing fewer than 15 letters from baseline best corrected visual acuity score in the study eye was comparable between two groups. The difference between Lupin’s ranibizumab and Lucentis^® for the proportion of patients who lost fewer than 15 letters was within the predefined equivalence margin (intention-to-treat population: 1.0%; 95% confidence interval [CI], −3.3% to 5.4% and per protocol population: 1.2%; 95% CI, −3.2% to 6.4%). The incidence of treatment-emergent adverse events was comparable, and 11 (10.89%) patients in Lupin’s ranibizumab and 19 (18.81%) patients in Lucentis^® group had at least one treatment-emergent adverse event. The immunogenicity incidence as assessed by proportion of patients with positive anti-drug antibodies was numerically lower in Lupin’s ranibizumab (4.95%) than Lucentis^® (12.87%).

Conclusion:

Lupin’s biosimilar ranibizumab demonstrated therapeutic equivalence, desirable safety, and favorable immunogenicity profile compared to Lucentis^®.

Comparison of Efficacy and Safety of Lupin’s Pegfilgrastim with Neulastim® as an Adjunct to Chemotherapy in Patients with Non Myeloid Malignancies: A Randomised Phase III Clinical Study

Introduction: Pegfilgrastim is indicated in patients receiving myelosuppressive anticancer drugs to reduce the Duration of Severe Neutropenia (DSN) and incidence of Febrile Neutropenia (FN). The efficacy and safety of a proposed pegfilgrastim biosimilar should be compared with an approved biologic drug to establish therapeutic equivalence. Aim: To compare the efficacy of Lupin’s biosimilar Pegfilgrastim versus Neulastim® (Amgen Inc.) as an adjunct to chemotherapy in patients with non-myeloid malignancies. Materials and Methods: The present prospective, open-label, randomised phase lll clinical study was conducted on a total of 170 patients with histologically or cytologically confirmed non-myeloid malignancies eligible to receive a myelosuppressive chemotherapy regimen. The participants were administered Lupin’s Pegfilgrastim (n=86) or Neulastim® (n=84) 6 mg by subcutaneous injection, once in each chemotherapy cycle for a maximum of three cycles. Patients were chemotherapy naive or had not received myelosuppressive chemotherapy within last 12 months of screening. The primary efficacy endpoint was DSN (number of days on which absolute neutrophil count <0.5×109 /L) in cycle 1 of chemotherapy. Equivalence was confirmed if 95% Confidence Intervals (CI) were within the equivalence margin of ±1 day. Safety evaluation included assessment of Adverse Events (AEs), rate of discontinuation due to AEs, vital signs, and laboratory parameters. Statistical analysis were done using SAS Enterprise guide 9.4 (SAS Institute Inc., Cary, 2000). Results: Of the 170 patients balanced for demographic characteristics, 161 patients completed cycle 1, 151 patients completed cycle 2, and 142 patients completed cycle 3. The mean±Standard Deviation (SD) DSN in cycle 1 was 0.127±0.5533 days with Pegfilgrastim (n=63) and 0.197±0.6615 days with Neulastim® (n=66) in the Per Protocol (PP) assessment; and 0.174±0.636 days with Pegfilgrastim and 0.193±0.671 days with Neulastim® in the modified Intent-to-Treat (mITT) assessment. The mean DSN between the groups did not differ significantly (PP: p=0.5167, mITT: p=0.8554). The 95% CI of difference in mean DSN in PP (-0.2796 to 0.1481) and mITT (-0.2103 to 0.1889) assessments was contained within the predefined equivalence margin of ±1 day. Secondary outcomes and safety profiles were also comparable between the two groups. Conclusion: The present study establishes Lupin’s Pegfilgrastim as a therapeutically equivalent biosimilar alternative to Neulastim® in patients with non-myeloid malignancies receiving myelosuppressive chemotherapy

Discovery of a Novel Potent and Selective Calcium Release-Activated Calcium Channel Inhibitor: 2,6-Difluoro-N-(2'-methyl-3'-(4-methyl-5-oxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)-[1,1'-biphenyl]-4-yl)benzamide. Structure-Activity Relationship and Preclinical Characterization

The role of calcium release-activated calcium (CRAC) channels is well characterized and is of particular importance in T-cell function. CRAC channels are involved in the pathogenesis of several autoimmune diseases, making it an attractive therapeutic target for treating inflammatory diseases, like rheumatoid arthritis (RA). A systematic structure-activity relationship study with the goal of optimizing lipophilicity successfully yielded two lead compounds, 36 and 37. Both compounds showed decent potency and selectivity and a remarkable pharmacokinetic profile. Further characterization in in vivo RA models and subsequent histopathological evaluation of tissues led to the identification of 36 as a clinical candidate. Compound 36 displayed an excellent safety profile and had a sufficient safety margin to qualify it for use in human testing. Oral administration of 36 in Phase 1 clinical study in healthy volunteers established favorable safety, tolerability, and good target engagement as measured by levels of IL-2 and TNF-α.

POS0598 COMPARISON OF INJECTION SITE REACTIONS AND INJECTION SITE ERYTHEMA BETWEEN YLB113 AND ETANERCEPT REFERENCE PRODUCT FROM PHASE 3 ACTIVE COMPARATOR STUDY (STUDY NO. YLB113-002)

Background:

YLB113 is an etanercept biosimilar approved in all indications of its etanercept Reference Product (RP). Therapeutic equivalence in terms of clinical efficacy, safety and immunogenicity was previously demonstrated in a pivotal multicenter, double-blind, randomized, parallel-group, active-control, comparative study (YLB113-002) in rheumatoid arthritis (RA) subjects.1,2 Similar incidence of treatment emergent adverse events (TEAEs) was seen in both treatment arms except for injection site reactions (ISRs) and injection site erythema (ISE), both of which were less frequent in subjects treated with YLB113.

Objectives:

This post-hoc analysis was performed to further evaluate the differences in the incidence of ISRs and ISE during the 24 week treatment when the subjects with RA were treated with 50 mg of YLB113 or RP given once a week as a SC injection along with methotrexate.

Methods:

Safety analysis set (263 in YLB113 arm and 254 in RP arm) was considered for this analysis.

Local reactions at the site of injection were assessed at each of eight study visits.

The number of subjects who experienced ISRs and ISE were statistically compared for YLB113 and RP. The risk difference and 95% confidence interval (CI) were computed between arms to understand the magnitude of difference in the incidence of events. The statistical significance of between group difference was tested using chi-square test.

Results:

The result of this analysis showed a statistically significant difference in the incidences of ISRs and ISE between subjects who received YLB113 and RP. The risk difference between YLB113 and RP arms for ISR was -9.98% (95% CI, WALD -14.81%, -5.15%) and, for ISE it was -7.94% (95% CI, WALD -11.96%, - 3.92%; Table 1). This could be possibly explained by the absence of latex in the syringe needle cap of YLB113.3

Table 1.

Differences in ISRs and ISEs between YLB113 and Reference Product (RP)

EventYLB113N=263RPN=254YLB113 vs RPNo of subjects with events [n(%)]No of subjects with events[n(%)])Risk Diff (95%CI, WALD)P-value (Chi-Square)Injection-site reactions10 (3.8%)35 (13.8%)-9.98% (-14.81%, -5.15%)<0.0001Injection-site erythema5 (1.9%)25 (9.8%)-7.94% (-11.96%, -3.92%)0.0001

Conclusion:

YLB113 has shown statistically significant lower incidences of ISRs (P-value <0.0001) and ISEs (P value 0.0001) compared to RP. This property may translate to a better acceptability by patients.

References:

[1]EULAR Abstract AB0416 (2019). Ann Rheum Dis, volume 78, supplement 2, year 2019, page A1670.

[2]Yamanaka H, Kamatani N, Tanaka Y, et al. A Comparative Study to Assess the Efficacy, Safety, and Immunogenicity of YLB113 and the Etanercept Reference Product for the Treatment of Patients with Rheumatoid Arthritis. Rheumatol Ther. 2020;7(1):149-163.

[3]Viatris Etanercept Summary of Product Characteritics May 2020.

Disclosure of Interests:

Dimitris Stefanidis Employee of: Viatris GmbH

Sr. Director, Global Medical Affairs Lead, Immunology Biosimilars, Unmesh G Employee of: Viatris, Juan Sánchez-Bursón: None declared, Chirag Shah Shareholder of: As an employee, Shareholder of Lupin LTD, Employee of: Employee of Lupin LTD, Dhananjay Bakhle Shareholder of: As part of Employee Stock Options Plan from Lupin LTD, Employee of: Employee of Lupin LTD

POS0604 LONG TERM SAFETY AND TOLERABILITY WITH ETANERCEPT BIOSIMILAR (YLB113), RESULTS FROM A 2-YEAR OPEN LABEL EXTENSION STUDY (STUDY NO. YLB113-003)

Background:

Eligible subjects with moderate-to-severely active rheumatoid arthritis (RA) who completed a phase 3 double-blind comparative efficacy and safety study (Study No. YLB113-002; Yamanaka et al, 2019) of 50 mg etanercept biosimilar (YLB113) or etanercept reference product (RP) by subcutaneous administration with concomitant MTX treatment for 52 weeks, were enrolled in this open label extension (OLE) study (Study No. YLB113-003) to assess the long-term safety and tolerability of YLB113 through to 3 years.

Objectives:

This OLE study aimed to evaluate the long-term safety of YLB113 administration in subjects with RA who received RP or YLB113 in a phase 3 active comparator study. The main parameters assessed were safety and tolerability in terms of adverse events (AEs) and injection site reactions (ISRs), incidence of immunogenicity and efficacy as DAS28 improvement (disease activity score in 28 joints).

Methods:

Subjects received 50 mg of YLB113 subcutaneously once every 1 to 2 weeks. Safety was assessed by AEs after study drug administration, ISRs, physical examination findings, and immunogenicity. Efficacy (DAS28 score) was assessed at the time of transition to the OLE study (Week 0), and at weeks 12, 24, 48, 72, 96 and at the end of the study.

Results:

201 (Full analysis set [FAS]) subjects received the study drug and 184 subjects completed the study (91.5% completion rate). The average drug exposure in 94 subjects who continued to receive YLB113 and completed the study (94.0% completion rate) and 90 subjects who switched from RP to YLB113 and completed the study (89.1% completion rate) was 103 weeks providing the long-term drug exposure data of YLB113.

The CTCAE Grade of TEAEs and ADRs observed were Grade 2 or less in severity (with no Grade ≥3). The overall incidence of ISRs was 10.0% (20/201 subjects) 77 events. All the ISRs reported were Grade 1 except for one Grade 2.

An overview of the AEs experienced by the subjects is summarized in the Table 1.

Table 1.

Overview of Adverse events in OLE study

FASn (%)Number of eventsNumber of subjects201-Treatment emergent adverse events (TEAEs)188(93.5)975Adverse drug reactions (ADRs)82(40.8)221Serious adverse events (SAEs)21(10.4)27Serious adverse drug reactions (SADRs)7(3.5)7AEs leading to premature study discontinuation4(2.0)6ADRs leading to premature study discontinuation3(1.5)4SAEs leading to premature study discontinuation3(1.5)4SADRs leading to premature study discontinuation2(1.0)2

n - number of subjects with at least 1 AE in the category

The mean DAS28 (mean ± S.D.) of 2.22 ± 0.95 at the study transition was 2.10 ± 0.91 at Week 72 and 2.06 ± 0.89 at the end of the study. It was confirmed that DAS28 slightly decreased with time after the study transition and continued until the end of the study. The average DAS28 value remained low even with long-term administration of YLB113, suggesting that the effects of the study drug was sustained (Figure 1).

Figure 1.

DAS28 over time with YLB113 N: Number of subjects. * The administration period at the study completion differs for each subject, because the study transition time differs for each subject.

cts who tested positive for anti-drug antibodies (ADA) at least once in the OLE study were 1.0% (2/200 subjects). All ADA were transient and disappeared at study completion. Such transient ADA formation was reported in the phase 3 study as well. In the phase 3 study, ADA formation was more frequent in subjects who received RP at 24 weeks, but all subjects were negative in the OLE study after switching. Therefore, switching did not affect immunogenicity.

Conclusion:

The safety, efficacy and immunogenicity profile of YLB113 was maintained over the long-term through to 3 years. Switching from RP to YLB113 did not impact safety or immunogenicity.

References:

[1]Yamanaka H, Kamatani N, Tanaka Y, et al. A Comparative Study to Assess the Efficacy, Safety, and Immunogenicity of YLB113 and the Etanercept Reference Product for the Treatment of Patients with Rheumatoid Arthritis. Rheumatol Ther. 2020 Mar;7(1):149-163.

Disclosure of Interests:

Yamanaka Hisashi Speakers bureau: YL Biologics Ltd, Consultant of: YL Biologics Ltd, Yoshiya Tanaka Speakers bureau: Received speaking fees and/or honoraria from Daiichi-Sankyo, Eli Lilly, Novartis, YL Biologics, Bristol-Myers, Eisai, Chugai, Abbvie, Astellas, Pfizer, Sanofi, Asahi-kasei, GSK, Mitsubishi-Tanabe, Gilead, Janssen., Grant/research support from: Received research grants from Abbvie, Mitsubishi-Tanabe, Chugai, Asahi-Kasei, Eisai, Takeda, Daiichi-Sankyo., Toshihiko Hibino: None declared, Chirag Shah Shareholder of: Lupin LTD, Employee of: Lupin LTD, Dhananjay Bakhle Shareholder of: As part of Employee Stock Options Plan of Lupin LTD, Employee of: Lupin LTD, Dimitris Stefanidis Employee of: Sr. Director, Global Medical Affairs Lead, Immunology Biosimilars for Viatris GmbH

Discovery of isoquinolinone and naphthyridinone-based inhibitors of poly(ADP-ribose) polymerase-1 (PARP1) as anticancer agents: Structure activity relationship and preclinical characterization

The exploitation of GLU988 and LYS903 residues in PARP1 as targets to design isoquinolinone (I & II) and naphthyridinone (III) analogues is described. Compounds of structure I have good biochemical and cellular potency but suffered from inferior PK. Constraining the linear propylene linker of structure I into a cyclopentene ring (II) offered improved PK parameters, while maintaining potency for PARP1. Finally, to avoid potential issues that may arise from the presence of an anilinic moiety, the nitrogen substituent on the isoquinolinone ring was incorporated as part of the bicyclic ring. This afforded a naphthyridinone scaffold, as shown in structure III. Further optimization of naphthyridinone series led to identification of a novel and highly potent PARP1 inhibitor 34, which was further characterized as preclinical candidate molecule. Compound 34 is orally bioavailable and displayed favorable pharmacokinetic (PK) properties. Compound 34 demonstrated remarkable antitumor efficacy both as a single-agent as well as in combination with chemotherapeutic agents in the BRCA1 mutant MDA-MB-436 breast cancer xenograft model. Additionally, compound 34 also potentiated the effect of agents such as temozolomide in breast cancer, pancreatic cancer and Ewing's sarcoma models.

An Open-Label, Randomized, Single-Dose, Crossover, Comparative Pharmacokinetics Study of YLB113 and the Etanercept Reference Product in Healthy Adult Male Subjects

BACKGROUND AND OBJECTIVES

YLB113 is being developed as a biosimilar of the antitumor necrosis factor-alpha antagonist etanercept, which is approved for the treatment of moderate-to-severe rheumatoid arthritis (RA) and other chronic immune-mediated inflammatory diseases. An open-label, crossover, pharmacokinetic study was conducted to compare the relative bioavailability and safety of YLB113 and the etanercept reference product (RP) Enbrel®.

METHODS

Healthy male subjects aged 18-50 years were randomized to receive a single subcutaneous dose of YLB113 in one period and the etanercept RP in another period. A washout period of 28 days separated the two treatment periods. Blood samples were collected for pharmacokinetic analysis predose and until 480 h postdose during both periods.

RESULTS

Overall, 52 subjects were enrolled, including 51 subjects who completed the first period and 43 subjects who completed the second period. The 90% confidence intervals for the least squares means derived from an analysis of the log-transformed pharmacokinetic parameters maximum serum concentration (Cmax), area under the serum concentration-time curve (AUC) from 0 to the last measurable concentration (AUC(0-t)) and AUC from 0 to infinity (AUC(0-∞)) for etanercept were between the limits of 80 and 125%. Thus, YLB113 met the bioequivalence criterion. YLB113 and the etanercept RP were well tolerated, with 24 subjects reporting 53 adverse events, including 42 mild and 11 moderate events. Treatment-emergent adverse events were reported by 14 and 16 subjects following the administration of YLB113 and the etanercept RP, respectively.

CONCLUSIONS

A single dose of YLB113 exhibited pharmacokinetic and safety profiles comparable with those of the etanercept RP in healthy adult male subjects. Therefore, YLB113 and the etanercept RP can be considered bioequivalent. These findings support the continued development of YLB113 for use in patients with RA.

JORDAN FOOD & DRUG ADMINISTRATION UNIQUE TRIAL NUMBER

31/Clinical/2018.

Discovery of Potent, Selective, and State-Dependent NaV1.7 Inhibitors with Robust Oral Efficacy in Pain Models: Structure-Activity Relationship and Optimization of Chroman and Indane Aryl Sulfonamides

Voltage-gated sodium channel Na_V1.7 is a genetically validated target for pain. Identification of Na_V1.7 inhibitors with all of the desired properties to develop as an oral therapeutic for pain has been a major challenge. Herein, we report systematic structure-activity relationship (SAR) studies carried out to identify novel sulfonamide derivatives as potent, selective, and state-dependent Na_V1.7 inhibitors for pain. Scaffold hopping from benzoxazine to chroman and indane bicyclic system followed by thiazole replacement on sulfonamide led to identification of lead molecules with significant improvement in solubility, selectivity over Na_V1.5, and CYP2C9 inhibition. The lead molecules 13, 29, 32, 43, and 51 showed a favorable pharmacokinetics (PK) profile across different species and robust efficacy in veratridine and formalin-induced inflammatory pain models in mice. Compound 51 also showed significant effects on the CCI-induced neuropathic pain model. The profile of 51 indicated that it has the potential for further evaluation as a therapeutic for pain.

A Comparative Study to Assess the Efficacy, Safety, and Immunogenicity of YLB113 and the Etanercept Reference Product for the Treatment of Patients with Rheumatoid Arthritis

Introduction

YLB113 is a biosimilar of the reference product (RP), etanercept, under development for treatment of patients with moderate-to-severe rheumatoid arthritis (RA) and other approved indications. A phase 3 study was conducted in Europe, Japan, and India to compare the efficacy, safety, and immunogenicity of YLB113 with the RP over a treatment period of 52 weeks.

Methods

Overall, 528 patients with moderate-to-severe RA receiving concomitant methotrexate were randomized to receive a once-weekly, subcutaneous dose of 50 mg YLB113 or the RP. The primary endpoint was ACR20 response rate at week 24, with similarity confirmed if the 95% confidence interval (CI) for YLB113 and the RP was within the range of − 15 to 15%. Safety and immunogenicity endpoints were assessed to week 52.

Results

Based on the European analysis, in the full analysis set, ACR20 response at week 24 was 83.3% and 88.5% for YLB113 and the RP, respectively. Responses were within the predefined clinical equivalence margin. The sensitivity analysis in the per protocol set revealed a similar proportion of subjects exhibiting ACR20 response at week 24 between groups, with a difference of − 5.1% (95% CI − 11.07 to 0.81). The incidence of treatment-emergent adverse events was comparable between groups, and the incidence of antidrug antibody development to week 24 favored YLB113 (0.8 vs. 8.3%).

Conclusions

This study demonstrated biosimilarity of YLB113 to the RP regarding efficacy, safety, and immunogenicity in patients with moderate-to-severe RA. Based on the same mechanism of action, biosimilarity could be extrapolated to other therapeutic indications approved for etanercept.

Trial registration

EudraCT Number: 2015-002,809-12.

Electronic Supplementary Material

The online version of this article (10.1007/s40744-019-00186-3) contains supplementary material, which is available to authorized users.

Discovery of Novel, Potent, Brain-Permeable, and Orally Efficacious Positive Allosteric Modulator of α7 Nicotinic Acetylcholine Receptor [4-(5-(4-Chlorophenyl)-4-methyl-2-propionylthiophen-3-yl)benzenesulfonamide]: Structure-Activity Relationship and Preclinical Characterization

The discovery of a series of thiophenephenylsulfonamides as positive allosteric modulators (PAM) of α7 nicotinic acetylcholine receptor (α7 nAChR) is described. Optimization of this series led to identification of compound 28, a novel PAM of α7 nicotinic acetylcholine receptor (α7 nAChR). Compound 28 showed good in vitro potency, with pharmacokinetic profile across species with excellent brain penetration and residence time. Compound 28 robustly reversed the cognitive deficits in episodic/working memory in both time-delay and scopolamine-induced amnesia paradigms in the novel object and social recognition tasks, at very low dose levels. Additionally, compound 28 has shown excellent safety profile in phase 1 clinical trials and is being evaluated for efficacy and safety as monotherapy in patients with mild to moderate Alzheimer's disease.