Drugs in Clinical Pipeline: RO-9021

RO-9021 [(1R,2S)-2-amino-cyclohexylamino]-4-(5,6-dimethyl-pyridin-2-ylamino)-pyridazine-3-carboxylic acid amide] is an oral, ATP-competative and selective inhibitor of spleen tyrosine kinase (SYK). RO-9021 potently inhibited SYK kinase activity with an average IC₅₀ of 5.6 nM. Selectivity of RO-9021 against a panel of 451 wild-type and mutant protein kinases was assessed using an ATP binding site competition assay developed by KINOMEscan Inc.  

RO-9021 is a highly selective SYK inhibitor with low S-scores of 0.003 for S(99) and 0.015 for S(90), indicating that SYK is the only kinase with 99% competition with RO-9021 (1 uM) in a total of 392 tested kinases. There were only a total of seven kinases (JAK1, JAK3, GCN2, SLK, FLT3(ITD), PAK2) including SYK, having more than 90% competition with RO9021. It inhibited JAK1 and JAK3 with 97% at 1 uM.

References:

1. Liao, C.; et. al. Selective inhibition of spleen tyrosine kinase (SYK) with a novel orally bioavailable small molecule inhibitor, RO9021, impinges on various innate and adaptive immune responses: implications for SYK inhibitors in autoimmune disease therapy. Arthritis Res Ther 2013, 15(5), R146.

Drugs in Clinical Pipeline: ONO-4059

ONO-4059 is a highly potent, oral and selective Bruton’s tyrosine kinase (Btk) inhibitor with an IC₅₀ of 2.2 nM in biochemical assay. The compound covalently binds to BTK, and reversibly blocks BCR signaling and B-cell proliferation and activation. In a selectivity assay, ONO-4059 shows a two-fold potency against TEC kinase (IC₅₀ = 5.3 nM) but it is highly selective against Fyn (IC₅₀ = 2200 nM), Lck (IC₅₀ = 790 nM) and LynA (IC₅₀ = 3500 nM) [1].

In December 2014, Gilead Sciences signed a contract to help expedite development of Ono Pharmaceutical’s Ono-4059 program. The firms plan to work together to develop and commercialize ONO-4059, an oral Bruton's tyrosine kinase (BTK) inhibitor for the treatment of B-cell malignancies and other diseases. Gilead will have exclusive rights to develop and commercialize ONO-4059 in all countries of the world outside of Japan, South Korea, Taiwan, China, and the Association of Southeast Asian Nations countries (ASEAN), where Ono retains development and commercialization rights. Gilead hopes to develop ONO-4059 as a monotherapy or in combination with approved and investigational agents, including combinations with kinase inhibitors in Gilead's portfolio.

The activity of ONO-4059 is as follows:

IC₅₀ (BTK enzyme assay) = 2.2 nM

IC₅₀ (TEC enzyme assay) = 5.3 nM

IC₅₀ (FYN enzyme assay) = 2200 nM

IC₅₀ (LCK enzyme assay) = 790 nM

IC₅₀ (LYNA enzyme assay) = 3500 nM

What's the structure of ONO-4059?

Till date, Ono pharma or Gilead pharma has not revealed the structure for ONO-4059. One of the patent publication in 2015 [3] provides some clues to ONO-4059. The biochemical assays correlates with those reported earlier [1, 2]. The IC₅₀ value for BTK is 0.0021 uM, with 375-fold selectivity against LCK, 1057-fold against FYN and 1662-fold against LYNA.

The stereo-chemistry is a beta position. Interestingly, the base molecule has IC₅₀ value for BTK as 0.007 uM, with 114-fold selectivity against LCK, 762-fold against FYN and 471-fold against LYNA [4].

Common Name: ONO-4059

Synonyms: ONO-4059; ONO 4059; ONO4059; GS 4059; GS-4059; GS4059; ONO-WG-307

IUPAC Name:

CAS Number: 

SMILES:

Mechanism of Action: Kinase Inhibitor; BTK Inhibitor; Bruton’s Tyrosine Kinase Inhibitor

Indication: Various Cancers; Anti-inflammatory Agents

Development Stage: Phase I/II

Company: Ono Pharmaceutical\Gilead Pharma

References:
1. Hendriks, R. W.; et. al. Targeting Bruton's tyrosine kinase in B cell malignancies. Nat Rev Cancer 2014, 14(4), 219-232.
2. Yoshizawa, T.; et. al. Development of a Bruton’s Tyrosine Kinase (Btk) inhibitor, ONO-4059: Efficacy in a Collagen Induced Arthritis (CIA) Model Indicates Potential Treatment for Rheumatoid Arthritis (RA). #1660, ACR, November 12, 2012. (here)
3. Yamamoto, S.; et. al. Purinone derivative hydrochloride. US20150274731A1
4. Yamamoto, S.; et. al. Purinone derivative. US20150094299A1

Drugs in Clinical Pipeline: GSK-2269557 | Treatment of COPD | Treatment of Asthma | Treatment of Autoimmune Diseases I PIK3d Inhibitor

GSK-2269557 [2-(6-(1H-indol-4-yl)-1H-indazol-4-yl)-5-((4-isopropylpiperazin-1-yl)methyl)oxazole] is a potent, selective nanomolar inhibitor of the delta isoform of the 110 kDa catalytic subunit of class IA phosphoinositide-3 kinases (PI3K). GSK-2269557 is more selective for PI3Kδ relative to other PI3K class I enzymes (pK_i: PI3Kδ = 9.9) with greater than 1000-fold selectivity over PI3Kα, PI3Kγ and PI3Kβ. It has a pIC₅₀ value greater than 7, with at least ten-fold selectivity for PI3Kδ over PI3Kα, PI3Kγ and PI3Kβ [1, 2].

GSK-2269557: 2D and 3D Structure

GSK-2269557 and GSK-2292767 are designed especially for the treatment of respiratory indications via inhalation. Both the drugs meet the criteria necessary for compounds to be delivered as aerosolized dry powder formulations. The advantages of delivering such inhibitors by this route are that it can minimize the risk of systemic, mechanism-related side effects and it also facilitates exploring combinations of the PI3Kδ inhibitors with other anti-asthma agents such as the corticosteroids [3]. 

GSK-2269557 is currently in Phase 2 clinical trials for chronic obstructive pulmonary disease (COPD) and asthma.

The activity of GSK-2269557 is as follows:

pIC₅₀ (PI3Kδ enzyme assay) = greater than 7

pK_i (PI3Kδ enzyme assay) = 9.9

Common Name: GSK-2269557

Synonyms: GSK-2269557; GSK2269557; GSK 2269557

IUPAC Name: 2-(6-(1H-indol-4-yl)-1H-indazol-4-yl)-5-((4-isopropylpiperazin-1-yl)methyl)oxazole

SMILES: 

CAS Number: 1254036-71-9; 1254036-77-5 (hydrochloride)

Mechanism of Action: Kinase Inhibitor; PI3K Inhibitor; PI3K delta Inhibitor

Indication: Treatment of COPD; Treatment of Asthma; Treatment of Autoimmune Diseases

Development Stage: Phase II

Company: GlaxoSmithKline

1H NMR (Estimated) for GSK-2269557

References:
1. Hamblin, J. N.; et. al. Oxazole substituted indazoles as pi3-kinase inhibitors. WO2010125082A1
2. Down, K.; et. al. Optimization of Novel Indazoles as Highly Potent and Selective Inhibitors of Phosphoinositide 3-Kinase d for the Treatment of Respiratory Disease. J Med Chem 2015, 58(18), 7381-7399.
3. Norman, P. Evaluation of WO2012032067 and WO2012055846: two selective PI3Kd inhibitors, which is GSK-2269557? Expert Opin Ther Pat 2012, 22(8), 965-970.

Drugs in Clinical Pipeline: Acalisib

Acalisib [(S)-2-(1-((7H-purin-6-yl)amino)ethyl)-6-fluoro-3-phenylquinazolin-4(3H)-one] is a potent, selective nanomolar inhibitor of the delta isoform of the 110 kDa catalytic subunit of class IA phosphoinositide-3 kinases (PI3K). 

Acalisib was more selective for PI3Kδ relative to other PI3K class I enzymes (IC₅₀: PI3Kδ = 12.7 nM; PI3Kα = 5441 nM; PI3Kβ = 3377 nM and PI3Kγ = 1389 nM). Acalisib was also 1000-fold more selective against PI3Kδ than against related kinases, such as CIIβ, hVPS34, DNAPK, and mammalian target of rapamycin (mTOR) [1].

Acalisib was also assayed for its potential binding interaction with kinases by screening a comprehensive panel of 393 kinases, including mutants, in the Ambit KINOMEscan. No binding outside of PI3K was observed at 10 µM Acalisib, further demonstrating a high degree of selectivity. Acalisib was considered active if less than 35% of binding to immobilized probes remained compared to DMSO control. Various PI3K isoforms have %control binding values in the 0.25-14 range. The next kinase target was PIP5K2B with a value of 49% [1].

Acalisib is under investigation for the treatment of lymphoid malignancies including non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) [2].

The activity of Acalisib is as follows:

IC₅₀ (PI3Kδ enzyme assay) = 12.7 nM

IC₅₀ (PI3Kα enzyme assay) = 5441 nM

IC₅₀ (PI3Kβ enzyme assay) = 3377 nM

IC₅₀ (PI3Kγ enzyme assay) = 1389 nM

IC₅₀ (DNA-PK enzyme assay) = 18.7 uM

IC₅₀ (mTOR enzyme assay) = greater than 1 uM

IC₅₀ (CIIβ enzyme assay) = greater than 1 uM

IC₅₀ (hVPS34 enzyme assay) = 12.6 uM

Common Name: Acalisib

Synonyms: GS-9820; GS9820; GS 9820; CAL-120; CAL 120; CAL120

IUPAC Name: (S)-2-(1-((7H-purin-6-yl)amino)ethyl)-6-fluoro-3-phenylquinazolin-4(3H)-one

CAS Number: 870281-34-8

Mechanism of Action: Kinase Inhibitor; PI3K Inhibitor; PI3Kdelta Inhibitor

Indication: Various Cancers; Anti-Tumor Agents; Autoimmune Disease Treatment

Development Stage: Phase I

Company: Gilead Sciences

References:
1. Shugg, R. P.; et. al. Effects of isoform-selective phosphatidylinositol 3-kinase inhibitors on osteoclasts: actions on cytoskeletal organization, survival, and resorption. J Biol Chem 2013, 288(49), 35346-35357.
2. Jun, S.; et. al. Interim Analysis Of A Phase 1B Study Evaluating The Safety Of GS-9820, A Second-Generation PI3Kd-Inhibitor, In Relapsed/Refractory Lymphoid Malignancies. 13th International Conference on Malignant Lymphoma. 17-20 June 2015 Lugano, Switzerland.

Drugs in Clinical Pipeline: ABT-494

ABT-494 [(3S,4R)-3-ethyl-4-(3H-imidazo[1,2-a]pyrrolo[2,3-e]pyrazin-8-yl)-N-(2,2,2-trifluoroethyl)pyrrolidine-1-carboxamide] is a second generation Jak kinase inhibitor with high selectivity for Jak1 (IC₅₀ = 0.043 uM) thereby minimizing the potential for side effects related to Jak2 (IC₅₀ = 0.2 uM) and Jak3 (IC₅₀ = 2.3 uM) inhibition. ABT-494 is an ATP competitive inhibitor, and is most potent against Jak1 with concentration at 50% inhibition (IC₅₀) of about 0.045 µM when tested at 0.1 mM ATP and less than 0.003 µM at 0.001 mM ATP [1].

Moreover, ABT-494 displays good selectivity in a panel of more than 60 protein kinases that also includes Jak3. Of the kinases in the panel, 14 kinases have an IC₅₀ below 10 µM, but only 2 non-Jak kinases have IC₅₀'s below 1 µM (Rock1 at 0.55 µM and Rock2 at 0.43 µM).

ABT-494 was engineered for increased selectivity for Jak1 using structural predictions that indicated the potential for differential binding interactions outside the ATP-binding active site of Jak1 but not Jak2. The efficacy and selectivity of ABT-494 were tested in a battery of relevant cellular and in vivo pharmacology assays including bone marrow colony formation, adjuvant induced arthritis (AIA), erythropoietin induced reticulocyte deployment and NK/NKT cell suppression [2]. 

ABT-494 demonstrates approximately 74 fold selectivity for Jak1 over Jak2 in cellular assays dependent on specific, relevant cytokines. ABT-494 is a potent inhibitor of inflammation and bone loss in rat AIA and, compared to Tofacitinib, spares relevant essential physiological processes such as erythropoietin signaling and peripheral NK cell counts at similarly efficacious doses in rats. When dosed orally for 14 days in healthy human subjects ABT-494 did not decrease reticulocyte or NK cell counts at predicted efficacious doses consistent with its pharmacodynamic properties in rats.

The activity of ABT-494 is as follows:

IC₅₀ (JAK1 enzyme assay) = 0.043 uM

IC₅₀ (JAK2 enzyme assay) = 0.2 uM

IC₅₀ (JAK3 enzyme assay) = 2.3 uM
IC₅₀ (TYK2 enzyme assay) = 4.7 uM
IC₅₀ (ROCK1 enzyme assay) = 0.55 uM

IC₅₀ (ROCK2 enzyme assay) = 0.43 uM

Common Name: ABT-494

Synonyms: ABT-494; ABT494; ABT 494

IUPAC Name: (3S,4R)-3-ethyl-4-(3H-imidazo[1,2-a]pyrrolo[2,3-e]pyrazin-8-yl)-N-(2,2,2-trifluoroethyl)pyrrolidine-1-carboxamide

CAS Number: 

Mechanism of Action: Kinase Inhibitor; Janus Kinase 1 Inhibitor

Indication: Anti-inflammatory Agents; Rheumatoid Arthritis Drug; Autoimmune Disease Treatment

Development Stage: Phase II

Company: AbbVie

References:
1. Voss, J. W.; et. al. Jak1 selective inhibitor and uses thereof. WO2015061665A1
2. Voss, J.; et. al. THU0127 Pharmacodynamics of A Novel JAK1 Selective Inhibitor in Rat Arthritis and Anemia Models and in Healthy Human Subjects. Ann Rheum Dis 2014, 73, 222.

Drugs in Clinical Pipeline: Entospletinib

Entospletinib [6-(1H-indazol-6-yl)-N-(4-morpholinophenyl)imidazo[1,2-a]pyrazin-8-amine] is an orally available, ATP competitive and highly selective Spleen tyrosine kinase (Syk) inhibitor which is being developed for treating autoimmune and oncology conditions. Broad kinase panel screening revealed a greater selectivity of entospletinib vs R406. Dissociation constant (K_d) determinations of the strongest hits from the broad panel KINOMEscan showed that aside from Syk itself, only 1 kinase, TNK1, had a K_d less than 100 nM for Entospletinib, whereas 79 kinases had K_d less than 100 nM for R406. In healthy volunteers, Entospletinib at BID doses higher than 200 mg demonstrated inhibition of Syk activity, as measured by CD63 expression and phospho-Syk. Due to its excellent selectivity profile, Entospletinib was hypothesized to provide high levels of Syk inhibition with potentially fewer off-target adverse effects (AEs) than observed with Fostamatinib [1, 2].

The activity of Entospletinib is as follows:

IC₅₀ (Syk enzyme assay) = 7.7 nM
IC₅₀ (pBLNK) = 26 nM

Common Name: Entospletinib

Synonyms:  GS-9973;  GS 9973; GS9973

IUPAC Name: 6-(1H-indazol-6-yl)-N-(4-morpholinophenyl)imidazo[1,2-a]pyrazin-8-amine

CAS Number: 1229208-44-9

Mechanism of Action: Kinase Inhibitor; Syk Inhibitor; Spleen Tyrosine Kinase Inhibitor

Indication: Various Cancers; Autoimmune diseases

Development Stage: Phase I/II

Company: Gilead Sciences

Spleen tyrosine kinase (Syk) is a 72 kDa multiple-domain intracellular cytoplasmic tyrosine kinase that is expressed primarily in hematopoietic cells (e.g., B-cells, monocytes, macrophages, mast cells, and neutrophils), where it is recognized as an important mediator of immunoreceptor signaling and has been identified as a potential therapeutic target in allergic, autoimmune, and oncology indications. Immunoreceptor engagement triggers phosphorylation of a pair of tyrosine residues in the cytoplasmic immunoreceptor tyrosine-based activation motifs (ITAMs) by Src family members, and Syk is recruited to the phosphorylated ITAMs via its SH2 domain.4-6 Syk critically regulates immune cell function by propagating signaling cascades through phosphorylation of direct targets (such as BLNK/SLP65), leading to activation of downstream pathways, including PI3K, MAPK, Btk, and PLCγ. The activation of these pathways in immune cells leads to proliferation, differentiation, cytoskeletal remodeling, and cytokine release. Importantly, since Syk is not expressed in mature T-cells, the immunosuppression that is associated with therapeutics that inhibit T-cell signaling should be avoided.

Entospletinib shows better kinase selectivity and oral availability than the most advanced Syk inhibitor, R406, (or its prodrug form Fostamatinib). R406 has shown efficacy in multiple therapeutic indications, but its clinical progress has been hampered by dose-limiting adverse effects that have been attributed, at least in part, to the off-target activities of R406. TNK1 is the only kinase that has less than 10-fold selectivity versus Syk for Entospletinib, whereas R406 bound 36 kinases within 10-fold of the potency of Syk and 14 kinases more potently than Syk [1]. 

References:

1. Currie, K. S.; et. al. Discovery of GS-9973, a selective and orally efficacious inhibitor of spleen tyrosine kinase. J Med Chem 2014, 57(9), 3856-3873.
2. Sharman, J.; et. al. An open-label phase 2 trial of entospletinib (GS-9973), a selective spleen tyrosine kinase inhibitor, in chronic lymphocytic leukemia. Blood 2015, 125(15), 2336-2343

3. ClinicalTrials.gov A Phase 1 Study of Novel GS-9973 Tablet Formulations to Evaluate the Effect of Acid Reducing Agents, Relative Bioavailability, and Food Effect on GS-9973 Pharmacokinetics. NCT01841489 (retrieved 25-04-2015)

4. ClinicalTrials.gov A Phase 2 of Entospletinib in Subjects With Relapsed or Refractory Hematologic Malignancies. NCT01799889 (retrieved 25-04-2015)

5. ClinicalTrials.gov  A Phase 2 of GS-9973 in Combination With Idelalisib in Subjects With Relapsed or Refractory Hematologic Malignancies. NCT01796470 (retrieved 25-04-2015)