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Syk inhibitors

Syk, a non-receptor protein tyrosine kinase, is a key mediator of immune receptor signaling and platelets. Syk, with Src homology 2 (SH2) domains, plays essential roles in signalling activated by various types of receptors such as FccR, CR3, Dectin-1 and apoptotic cell-recognizing receptor. Syk also plays an important part in the uncontrolled growth of tumor cells. The tandem SH2-domain-containing Syk is activated when classical ITAMs is tyrosine-phosphorylated by SRC kinases. The downstream of syk includes Ras, Raf and MAPK signaling pathway.

Other Angiogenesis Related Inhibitors

Src FGFR HIF Bcr-Abl VDA FLT3 FAK BTK ANGPTL FLT

Isoform-selective Products

Cat.No. Product Name Information Product Use Citations Product Validations
S2194 R406 R406(R406 besylate) is a potent Syk inhibitor with IC50 of 41 nM in cell-free assays, strongly inhibits Syk but not Lyn, 5-fold less potent to Flt3. R406 induces apoptosis. Phase 1.
J Allergy Clin Immunol, 2025, 155(2):569-582
Int J Biol Sci, 2025, 21(12):5287-5304
Front Immunol, 2025, 16:1636917
Verified customer review of R406
S1533 R406 (free base) R406 (free base) is a potent Syk inhibitor with IC50 of 41 nM in a cell-free assay, strongly inhibits Syk but not Lyn, 5-fold less potent to Flt3. This compound triggers apoptosis. Phase 1.
Autophagy, 2025, 1-17.
EMBO Rep, 2025, 10.1038/s44319-025-00444-2
J Transl Med, 2024, 22(1):283
Verified customer review of R406 (free base)
S8032 PRT062607 (P505-15) HCl PRT062607 (P505-15, BIIB057, PRT-2607) HCl is a novel, highly selective Syk inhibitor with IC50 of 1 nM in cell-free assays, >80-fold selective for Syk than Fgr, PAK5, Lyn, FAK, Pyk2, FLT3, MLK1 and Zap70.
Sci Adv, 2025, 11(31):eadu4270
Sci Rep, 2024, 14(1):7739
J Exp Med, 2023, 220(9)e20230054
Verified customer review of PRT062607 (P505-15) HCl
S7523 Entospletinib (GS-9973) Entospletinib (GS-9973) is an orally bioavailable, selective Syk inhibitor with IC50 of 7.7 nM in a cell-free assay. This compound showed 13- to >1000-fold cellular selectivity for Syk over other kinases (including Jak2, ckit, Flt3, Ret, KDR) as assessed by target protein phosphorylation or functional response.
Cancer Res, 2023, 83(2):316-331
Front Immunol, 2023, 14:1279155
J Leukoc Biol, 2023, qiad025
Verified customer review of Entospletinib (GS-9973)
S2625 Fostamatinib (R788) Fostamatinib (R788), a prodrug of the active metabolite R406, is a Syk inhibitor with IC50 of 41 nM. It strongly inhibits Syk but not Lyn, and is 5-fold less potent to Flt3. Phase 3.
Autophagy, 2025, 1-17.
Int Immunopharmacol, 2025, 148:114122
Exp Ther Med, 2025, 29(6):110
Verified customer review of Fostamatinib (R788)
S3026 Piceatannol Piceatannol, a natural stilbene, is a selective Syk inhibitor and ~10-fold selectivity versus Lyn.
Autophagy, 2025, 1-17.
Int J Mol Sci, 2025, 26(18)9134
ACS Appl Mater Interfaces, 2022, 14(21):24144-24159
Verified customer review of Piceatannol
S2206 R788 (Fostamatinib) Disodium Fostamatinib disodium (R788, Tamatinib Fosdium), a prodrug of the active metabolite R406, is a Syk inhibitor with IC50 of 41 nM in a cell-free assay, strongly inhibits Syk but not Lyn, 5-fold less potent to Flt3. Phase 3.
Autophagy, 2025, 1-17.
Sci Rep, 2025, 15(1):25312
FASEB J, 2024, 38(6):e23564
Verified customer review of R788 (Fostamatinib) Disodium
S7006 BAY 61-3606 dihydrochloride BAY 61-3606 dihydrochloride is a potent and selective inhibitor of Syk kinase (Ki = 7.5 nM). BAY-61-3606 induces cell cycle arrest and apoptosis.
EMBO Rep, 2025, 10.1038/s44319-025-00444-2
bioRxiv, 2025, 2025.05.30.657101
Arterioscler Thromb Vasc Biol, 2024, 44(7):1646-1657
S7738 PRT-060318 2HCl PRT-060318 (PRT318) is a novel selective inhibitor of the Syk tyrosine kinase with an IC50 of 4 nM, as an approach to HIT treatment.
Microbiol Spectr, 2025, 13(1):e0254921
Cell Mol Life Sci, 2024, 82(1):14
PLoS Pathog, 2024, 20(10):e1012674
S8442 TAK-659 Hydrochloride TAK-659 Hydrochloride is a potent and selective inhibitor of spleen tyrosine kinase (SYK) with an IC50 value of 3.2 nM. It is selective against most other kinases, but potent toward both SYK and FLT3.
Exp Ther Med, 2025, 29(6):110
Int J Mol Sci, 2024, 25(18)9914
Int J Mol Sci, 2022, 23(23)14706

Signaling Pathway Map