Table 1.

Structures, IC₅₀ values, and the most important biological results of the reviewed pyrazole-based kinase inhibitors.

Kinase	Inhibitor	IC50 Value in Cell-Free Assay (nM)	Other Biological Activities
AKT1		61	Antiproliferative activity against HCT116 and OVCAR-8 cell lines (IC50 = 7.76 and 9.76 µM, respectively)
		1.3	Antiproliferative activity against HCT116 colon cancer cell line (IC50 = 0.95 µM). Reduction of tumor size by 42% in the MM1S model.
ALK		2.9	Reduction of phosphorylation of ALK in hippocampus in a dose-dependent manner at 30 mg/kg and higher. Inhibited phosphorylation in prefrontal cortex at 100 mg/kg.
ASK1		-	Good CNS penetration. Weak potency against hERG, CYP3A4, and CYP2C9.
Aurora	(Barasertib, AZD1152)	0.37 (Aurora B)	Passed phase I clinical trials in Japanese and Western volunteers suffering from advanced acute myeloid leukemia.
		160 (Aurora A)	IC50 values against HCT116 colon cancer and MCF7 breast cancer cell lines are 0.39 and 0.46 µM, respectively.
		28.9 (Aurora A) 2.2 (Aurora B)	IC50 values against U937 (leukemia), K562 (leukemia), A549 (lung), LoVo (colon), and HT29 (colon) cancer cell lines are 5.106, 5.003, 0.487, 0.789, and 0.381 µM, respectively.
		35 (Aurora A) 75 (Aurora B)	Antiproliferative activity against SW620 and HCT116 colon cancer cell lines (IC50 = 0.35 and 0.34 µM, respectively).
		0.316 (Aurora B)	Antiproliferative activity against MDA-MB-468 with IC50 value equal to 107 nM.
BCR-ABL		14.2	Antiproliferative activity against the K562 leukemia cell line with an IC50 value equal to 0.27 µM.
		8.5	Antiproliferative activity against the K562 leukemia cell line with an IC50 value less than 2 nM.
		0.5	IC50 = 25 nM against ABL (T315I). Clinical candidate for CML.
Calcium-dependent kinase		56	Anti-parasitic activity against Plasmodium falciparum with an IC50 value of 0.262 µM.
		0.7	Anti-parasitic activity against Cryptosporidium parvum with an EC50 value of 0.41 µM.
		2.5	Anti-parasitic activity against Cryptosporidium parvum with an EC50 value of 0.51 µM.
Checkpoint kinase 2		48.4	Antiproliferative activity against HepG2 (hepatocellular carcinoma), HeLa (cervical), and MCF7 (breast) cancer cell lines.
		17.9	Antiproliferative activity against HepG2 (hepatocellular carcinoma), HeLa (cervical), and MCF7 (breast) cancer cell lines (IC50 = 10.8, 11.8, and 10.4 µM, respectively).
		41.64	Modest potency against HepG2, HeLa, and MCF7 cell lines with 2-digit micromolar IC50 values.
Cyclin-dependent kinases		420 (CDK4)	Modest antiproliferative activity against K562, MCF7, and RPMI-8226 cancer cell lines. Induced apoptosis in RPMI-8226 cells.
		-	IC50 values against MCF7 cells (IC50 = 0.13 µM), MIAPaCa pancreatic cancer cell line (IC50 = 0.28 µM), and HeLa cervical cancer cell line (IC50 = 0.21 µM).
		-	IC50 values against MCF7 cells (IC50 = 0.15 µM), MIAPaCa pancreatic cancer cell line (IC50 = 0.34 µM), and HeLa cervical cancer cell line (IC50 = 0 0.73 µM).
		24 (CDK2) 23 (CDK5)	Induction of apoptosis in the MiaPaCa2 pancreatic cancer cell line.
		10–210 (multiple CDK inhibitor)	Induction of apoptosis in colon cancer and multiple myeloma cells.
		2380 (CDK1)	Antiproliferative activity against hepatocellular carcinoma (HepG2, Huh7, and SNU-475), colon cancer (HCT116), and renal cancer (UO-31) cell lines (IC50 = 0.05, 0.065, 1.93, 1.68, and 1.85 µM, respectively).
		1520 (CDK1)	Antiproliferative activity against hepatocellular carcinoma (HepG2, Huh7, and SNU-475), colon cancer (HCT116), and renal cancer (UO-31) cell lines (IC50 = 0.028, 1.83, 1.70, 0.035, and 2.24 µM, respectively).
		88 (CDK14)	Antiproliferative activity against HCT116 colorectal cancer cell line (IC50 = 1.14 µM).
		8.63 (CDK1) 0.30 (CDK2)	Inhibitory effect against HDAC1, HDAC2, and HDAC3 (IC50 = 6.40, 0.25, and 45.0 nM, respectively). Antiproliferative activity against HCT116 colorectal cancer cell line (IC50 = 0.71 µM).
		9 (CDK12) 5.8 (CDK13)	-
EGFR		210	Antiproliferative effect against MCF-7 breast cancer cell line (IC50 = 0.30 μM).
FGFR		0.2 (FGFR1) 2.5 (FGFR2) 1.8 (FGFR3) 165 (FGFR4)	Orally bioavailable, clinical candidate for lymphoma, glioma, lung, breast, gastric, and esophageal types of cancer.
		9.3 (FGFR1) 7.6 (FGFR2) 22 (FGFR3) 290 (FGFR4)	Antiproliferative IC50 values against gastric SNU-16 and colon HCT116 cancer cell lines are 17 nM and 5.9 µM, respectively.
		0.75 (FGFR1) 0.5 (FGFR2) 3.05 (FGFR3) 87.9 (FGFR4)	Antiproliferative activity against FGFR-2-amplified SNU-16 gastric cancer cell line (IC50 = 85.64 nM).
IKK		-	Antiproliferative activity against HeLa cervical cancer cell line (IC50 = 14.2 μg/mL).
IRAK4		5	Strong potency (IC50 = 83 nM) against lipopolysaccharide-induced THP1-XBlue cells.
		0.4	Good permeability (25 × 10−6 cm/s) in MDCK cells.
		0.51	-
ITK		Ki = 0.1 nM	Multi-kinase inhibitor.
		Ki = 0.5 nM	Higher kinase selectivity, permeability, and oral bioavailability than compound 37.
		Ki = 0.09 nM	Improved potency, selectivity, and less toxicity.
JAK		3.4 (JAK1) 2.2 (JAK2) 3.5 (JAK3)	Antiproliferative activity: IC50 against PC-3 IC50 = 1.08 μM, MCF-7 IC50 = 1.33 μM, HEL IC50 = 1.08 μM, K562 IC50 = 0.77 μM, MOLT4 IC50 = 1.61 μM.
		-	Antiproliferative activity against HEL (IC50 = 0.35 μM) and K562 (IC50 = 0.37 μM).
		Ki = 2.5 nM (JAK2)	Potent inhibitory activity in a JAK2-driven SET2 cell-based assay (IC50 = 131 nM). Low potential for reversible inhibition of five major human CYP450 isozymes, and good in vitro permeability profile.
		Ki = 0.21 nM (JAK1) Ki = 0.088 nM (JAK2)	IC50 of 4.7 nM in IL-13 stimulated BEAS-2B cells.
		Ki = 0.31 nM (JAK1) Ki = 0.14 nM (JAK2)	IC50 of 6.4 nM in the IL-13-pSTAT6 cell-based assay.
		75(JAK1) 1.1 (JAK2) 360 (JAK3)	In vivo reduction of reticulocytes and subsequent reductions in red blood cell mass as well as a decrease in platelets.
JNK		2800 (JNK1)	In vivo anti-inflammatory activity against carrageenan-induced paw edema model in rats.
		227 (JNK3)	-
LRRK		9 (LRRK2)	-
	(GNE-0877)	0.7 (LRRK2)	Improved human hepatocyte stability, brain exposure, and lower ability to inhibit or induce CYP compared to compound 48.
	(GNE-9605)	2 (LRRK2)	Improved human hepatocyte stability, brain exposure, and lower ability to inhibit or induce CYP compared to compound 48.
		-	-
		Ki = 84 nM (wild-type LRRK2) and 39 nM (G2019S mutant type LRRK2)	98% oral bioavailability.
LsrK		119,000	-
MEK/ERK		-	Antiproliferative activity against the A375P melanoma cell line (IC50 = 6.7 µM).
		-	Antiproliferative activity against the MDA-MB-435 melanoma cell line (IC50 = 2.7 µM). Kinase inhibition was confirmed by Western blotting. IC50 = 0.30 µM against COX-2.
		-	IC50 = 91 nM against recombinant proteins of the RAF-MEK-ERK cascade. GI50 of 1.18, 2.11, and 0.26 μM against HeLa, MCF-7, and A549 cell lines, respectively.
P38α/MAPK14		22	Inhibition of TNF-α production in lipopolysaccharide-stimulated THP-1 human cells. In vivo anti-inflammatory activity.
		135	Poor cellular permeability due to its highly charged carboxylate group. Its ethyl ester analogue could inhibit phosphorylation of MK2 in HeLa cells (IC50 value = 6 µM) but its IC50 value against p38α is 639 nM.
	(VPC00628)	7	High selectivity against p38α and p38β.
		515	Antiproliferative activity against RPMI-8226 and K-562 leukemia cell lines in addition to the MDA-MB-468 breast cancer cell line (IC50 values are 1.71, 3.42, and 6.70 µM, respectively).
PDK4		84	Enhanced glucose tolerance in a diet-induced obesity model in mice. Alleviated the allergic reactions in a passive cutaneous anaphylaxis model in mice.
Pim		Ki = 0.073 nM (Pim1), 0.473 (Pim2), and 0.041 (Pim3)	Antiproliferative activity against MM1.s myeloma cell line (IC50 = 0.64 µM).
		Ki = 0.03 nM (Pim1), 0.1 (Pim2), and 0.02 (Pim3)	Promising in vivo activity against MM1.s and RPMI 8226 mice models of multiple myeloma.
RAF		-	Antiproliferative activity against the A375P melanoma cell line (IC50 = 4.5 µM).
		0.04 (wild-type B-RAF)	Its trans isomer (with the hydroxyl group behind the plane) is less potent against the kinase (IC50 = 0.09 nM).
		330 (V600E-B-RAF)	Antiproliferative activity against WM266.4 and A375 melanoma cell lines with IC50 values of 2.63 and 3.16 µM, respectively
		770 (V600E-B-RAF) and 1500 (RAF1)	One-digit micromolar IC50 values against different cancer cell lines.
		2.98 (V600E-B-RAF)	Antiproliferative activity against the A375 melanoma cells (IC50 = 1.82 µM).
		99.17% inhibition at 10 µM (V600E-B-RAF)	IC50 values within sub-micromolar range (0.27–0.92 µM) against nine cancer cell lines of nine cancer types. Against the A375 melanoma cell line, its IC50 value is 0.82 µM.
		-	78.04%, 74.47%, and 72.46% inhibition at 10 µM concentration against RAF1, V600E-B-RAF, and V600K-B-RAF kinases, respectively.
		7 (V600E-B-RAF)	Mean IC50 value against the NCI nine subpanels was within the range of 1.98–3.26 µM.
		390 (V600E-B-RAF)	IC50 values are within the submicromolar range against most of the tested cell lines (NCI-60 panel). Induced apoptosis in the RPMI-8226 leukemia cell line with an EC50 of 1.52 µM.
ROS		13.6	-
Src		59% inhibition at 10 µM concentration	Antiproliferative activity against CCRF-CEM and MOLT-4 leukemia cell lines (IC50 = 1.00 µM against both of them).
TGFβ/ALK		684 (R206H mutated ALK2)	Promising lead compound for treatment of fibrodysplasia ossificans progressive.
		25.6 (R206H mutated ALK2)	Good permeability and in vivo pharmacokinetic properties.
		9.4	Promising lead compound for treatment of fibrodysplasia ossificans progressive. Improved aqueous solubility compared to compound 75.
		13 (TGFβ type 1/ALK5)	Inhibited luciferase activity by 80% at 0.1 μM. In-cell kinase inhibition.
		280 (TGFβ type 1/ALK5)	>35-fold more selective against ALK5 compared to p38α MAPK.
		18 (TGFβ type 1/ALK5)	In-cell kinase inhibition.
		69 (TGFβ type 1/ALK5)	Inhibitory effects against the p38α kinase (IC50 = 104 nM).
		30 (TGFβ type 1/ALK5)	Potential inhibitor of collagen I and α-SMA protein and mRNA expressions in TGFβ-induced LX-2 human hepatic stellate cells.
Trk		2 (TrkA) 8 (TrkB)	-
		-	Potent inhibitor of TrkA with an IC50 value of 0.5 nM in a cellular assay. 29% oral bioavailability. High aqueous solubility and safety against hERG.
		-	Potent inhibitor of TrkA with an IC50 value of 0.5 nM in a cellular assay.54% oral bioavailability. High aqueous solubility and safety against hERG.
		2.7 (TrkA)	Higher selectivity against TrkA than TrkB and TrkC.
		-	Rapid association rate with the TrkA crystal structure, thus binds to the inactive conformation of the kinase (i.e., type II TrkA inhibitor).
		0.2 (TrkA)	In vivo activity in CFA-induced thermal hypersensitivity model.
VEGFR		0.95 (VEGFR2)	Decreased the proliferation of VEGF stimulated HUVEC with an IC50 of 0.30 nM. In vivo anticancer activity in a mouse xenograft model of human lung adenocarcinoma A549 cells.
		97 (VEGFR2)	Antiproliferative activity against HT-29 colon cell line (IC50 = 3.32 μM), PC-3 prostate cells (IC50 = 3.17 μM), A549 lung cells (IC50 = 3.87 μM), and U87MG glioblastoma cells (IC50 = 6.77 μM).
		-	In-cell kinase inhibition. Antiproliferative activity against the MCF-7 cell line (IC50 = 18.35 µM).
Multikinase inhibitors		Inhibitor of VEGFR2, Src, B-RAF (wild-type), V600E-B-RAF, EGFR (wild-type), and L858R-EGFR with IC50 values of 34, 399, 270, 592, 113, and 31 nM, respectively.
		Multi-kinase inhibitory effects against AKT2, GSK-3β, PI3K, EGFR, IGFR, CDK2, Aurora A, and MAPK.	Antiproliferative activity against SNU449 hepatocellular carcinoma cell line.
		Multikinase inhibitory effects against AKT2, GSK-3β, PI3K, EGFR, IGFR, CDK2, Aurora A, and MAPK.	Antiproliferative activity against SNU449 hepatocellular carcinoma cell line.
		Dual KDR/Aurora B activity	Narrow therapeutic index.
		Inhibitory effect against B-RAF (wild-type), V600E-B-RAF, p38α, JNK1, and JNK2 kinases (inhibition % values at 10 µM concentration are 72.56%, 93.67%, 86.54%, 99.05%, and 98.49%, respectively).	Antiproliferative activity against the A498 renal carcinoma cell line (IC50 = 0.33 µM). JNK1 and JNK2 are the most sensitive among them (IC50 = 350 and 360 nM, respectively).
		>94% inhibition of AKT1, AKT2, V600E-B-RAF, EGFR, p38α, and PDGFRβ at 100 µM.	Antiproliferative activity against MCF7 breast cancer cell line (IC50 = 6.53 µM).
		c-Kit, FLT-3, VEGFR-2, EGFR, PDGFR, and Pim-1 kinases (IC50 260–610 nM).	Antiproliferative activity against A549 (lung), H460 (lung), HT29 (colon), MKN-45 (gastric), U87MG (glioma), and SMMC-77217721 (hepatic) cancer cell lines (IC50 values from 0.29–0.42 µM).
		JAK2, JAK3, Aurora A, and Aurora B (IC50 = 166, 57, 939, 583 nM, respectively).	Antiproliferative activity against K562 leukemia cell line and HCT116 colon cancer cell line (IC50 = 6.726 and 15.054 µM, respectively).
		Inhibited B-RAF, C-RAF, and Src kinases both in vitro and in vivo.	In vivo activity and phase I clinical trials in volunteers with solid tumors. Increased the progression-free survival in a patient suffering from KRAS (G12V) spindle cell sarcoma.