Discovery of 3-Aminopyrazole Derivatives as New Potent and Orally Bioavailable AXL Inhibitors.

The receptor tyrosine kinase AXL is a promising target for anticancer drug discovery. Herein, we describe the discovery of 3-aminopyrazole derivatives as new potent and selective AXL kinase inhibitors. One of the representative compounds, 6li, potently inhibited AXL enzymatic activity with an IC50 value of 1.6 nM, and tightly bound with AXL protein with a Kd value of 0.26 nM, while was obviously less potent against most of the 403 wild-type kinases evaluated. Cell-based assays demonstrated that compound 6li potently inhibited AXL signaling, suppressed Ba/F3-TEL-AXL cell proliferation, reversed TGF-ß1-induced epithelial-mesenchymal transition, and dose-dependently impeded cancer cell migration and invasion. Compound 6li also showed reasonable pharmacokinetic properties in rats and exhibited significant in vivo antitumor efficacy in a xenograft model of highly metastatic murine breast cancer 4T1 cells. Taken together, this study provides a new potent and selective AXL inhibitor for further anticancer drug discovery.

JND4135, a New Type II TRK Inhibitor, Overcomes TRK xDFG and Other Mutation Resistance In Vitro and In Vivo.

The tropomyosin receptor kinases (TRKs) have been validated as effective targets in anticancer drug discovery. Two first-generation TRK inhibitors have been approved into market and displayed an encouraging therapeutic response in cancer patients harboring TRK fusion proteins. However, acquired resistance mediated by secondary TRK mutations especially in the xDFG motif remains an unsolved challenge in the clinic. Herein, we report the preclinical pharmacological results of JND4135, a new type II pan-TRK inhibitor, in overcoming TRK mutant resistance, including the xDFG mutations in vitro and in vivo. At a low nanomolar level, JND4135 displays a strong activity against wild-type TRKA/B/C and secondary mutations involving xDFG motif substitutions in kinase assays and cellular models; occupies the TRK proteins for an extended time; and has a slower dissociation rate than other TRK inhibitors. Moreover, by intraperitoneal injection, JND4135 exhibits tumor growth inhibition (TGI) of 81.0% at a dose of 40 mg/kg in BaF3-CD74-TRKA-G667C mice xenograft model. Therefore, JND4135 can be considered as a lead compound for drug discovery overcoming the resistance of TRK inhibitor drugs mediated by xDFG mutations.

Discovery of Hexahydrofuro[3,2-b]furans as New Kinase-Selective and Orally Bioavailable JAK3 Inhibitors for the Treatment of Leukemia Harboring a JAK3 Activating Mutant.

Janus kinase 3 (JAK3) is a potential target for the treatment of hematological malignancies. Herein, we report the discovery of a series of new orally bioavailable irreversible JAK3 kinase inhibitors. The representative compound 12n potently inhibited JAK3 kinase activity with an IC50 value of 1.2 nM and was more than 900-fold selective over JAK1, JAK2, and Tyk2. Cell-based assays revealed that 12n significantly suppressed phosphorylation of JAK3 and the downstream effectors STAT3/5 and also robustly restrained proliferation of BaF3 cells transfected with JAK3M511I activating mutation and human leukemia U937 cells harboring JAK3M511I with IC50 values of 22.9 and 20.2 nM, respectively. More importantly, 12n showed reasonable pharmacokinetic (PK) properties, and oral administration of 12n at a dose of 50 mg/kg twice daily led to tumor regression in a U937 cell inoculated xenograft mouse model. Thus, 12n represents a promising lead compound for further optimization to discover new therapeutic agents for hematological malignancies.

ASK120067 potently suppresses B-cell or T-cell malignancies in vitro and in vivo by inhibiting BTK and ITK.

Hyperactivation of Bruton's tyrosine kinase (BTK) or interleukin-2-inducible T cell kinase (ITK) has been attributed to the pathogenesis of B-cell lymphoma or T-cell leukemia, respectively, which suggests that Bruton's tyrosine kinase and interleukin-2-inducible T cell kinase are critical targets for the treatment of hematological malignancies. We identified a novel third-generation epidermal growth factor receptor (EGFR) inhibitor, ASK120067 (limertinib) in our previous research, which has been applied as a new drug application against non-small cell lung cancer in China. In this work, we found that ASK120067 displayed potent in vitro inhibitory efficacy against Bruton's tyrosine kinase protein and interleukin-2-inducible T cell kinase protein via covalent binding. In cell-based assays, ASK120067 dose-dependently suppressed Bruton's tyrosine kinase phosphorylation and exhibited anti-proliferation potency by inducing apoptosis in numerous B-lymphoma cells. Meanwhile, it caused growth arrest and induced the apoptosis of T-cell leukemia cells by attenuating interleukin-2-inducible T cell kinase activation. Oral administration of ASK120067 led to significant tumor regression in B-cell lymphoma and T-cell leukemia xenograft models by weakening Bruton's tyrosine kinase and interleukin-2-inducible T cell kinase signaling, respectively. Taken together, our studies demonstrated that ASK120067 exerted preclinical anti-tumor activities against B-/T-cell malignancy by targeting BTK/ITK.

GZD824 overcomes FGFR1-V561F/M mutant resistance in vitro and in vivo.

Abnormallyactivated FGFR1 has been validated as a therapeutic target for differentcancers. Although a variety of FGFR inhibitors have shown benefit in manyclinical patients with FGFR1 aberration, FGFR1 mutant resistance such as V561Mmutation, has been reported. To date however, no FGFR inhibitors have beenapproved to treat patients with FGFR mutant resistance. Herein, we report that GZD824, athird generation ABL inhibitor (Phase II, China), overcomes FGFR1-V561F/M mutant resistance in vitro and in vivo. GZD824potently suppresses FGFR1/2/3 with an IC50 value of 4.14 ± 0.96, 2.77 ± 0.082, and 8.10 ± 0.15 nmol/L. It effectively overcomes FGFR1-V561F/M and other mutantresistance in Ba/F3 stable cells (IC50 :8.1-55.0 nM), and effectively inhibits the growth of Ba/F3-FGFR1-V561F/M mutantxenograft tumors in vivo (TGI=73.4%, 49.8% at20mg/kg, p.o, q2d). GZD824may be considered to be an effective drug to treat patients with FGFR1 abnormalactivation or mutant resistance in clinical trials.

Design, synthesis, and Structure-Activity Relationships (SAR) of 3-vinylindazole derivatives as new selective tropomyosin receptor kinases (Trk) inhibitors.

Neurotrophic receptor tyrosine kinase (NTRK) fusions are oncogenic drivers for a variety of adult and pediatric tumors, validated by the US FDA approval of small molecular Trk inhibitors Larotrectinib (1, LOXO-101) and Entrectinib (2). However, gene mutation mediated resistance becomes a major challenge for Trk inhibitor therapies. Herein, we report the design, synthesis and Structure-Activity Relationship investigation of a series of 3-vinylindazole derivatives as new Trk inhibitors with low nanomolar potencies. A representative compound, 7mb, binds to TrkA/B/C with Kd values of 1.6, 3.1 and 4.9 nM, and suppresses their kinase functions with IC50 values of 1.6, 2.9 and 2.0 nM, respectively, but is obviously less potent for the majority of a panel of 403 wild-type kinases in a KINOMEscan selectivity investigation. The compound also potently suppresses proliferation of a panel of BaF3 cells stably transformed with NTRK fusions with IC50 values in low nM ranges. Additionally, the compound exhibits strong inhibition against the Larotrectinib-resistant cells with NTRK1-G667C or NTRK3-G696A mutations with IC50 values of 0.031 and 0.018 µM, respectively. Although the relatively poor oral bioavailability of 7mb will limit its further development, this compound may be utilized a lead molecule for further structural optimization.

Discovery of a novel third-generation EGFR inhibitor and identification of a potential combination strategy to overcome resistance.

BACKGROUND: Non-small cell lung cancer (NSCLC) patients with activating EGFR mutations initially respond to first-generation EGFR inhibitors; however, the efficacy of these drugs is limited by acquired resistance driven by the EGFR T790M mutation. The discovery of third-generation EGFR inhibitors overcoming EGFR T790M and their new resistance mechanisms have attracted much attention. METHODS: We examined the antitumor activities and potential resistance mechanism of a novel EGFR third-generation inhibitor in vitro and in vivo using ELISA, SRB assay, immunoblotting, flow cytometric analysis, kinase array, qRT-PCR and tumor xenograft models. The clinical effect on a patient was evaluated by computed tomography scan. RESULTS: We identified compound ASK120067 as a novel inhibitor of EGFR T790M, with selectivity over EGFR WT. ASK120067 exhibited potent anti-proliferation activity in tumor cells harboring EGFR T790M (NCI-H1975) and sensitizing mutations (PC-9 and HCC827) while showed moderate or weak inhibition in cells expressing EGFR WT. Oral administration of ASK120067 induced tumor regression in NSCLC xenograft models and in a PDX model harboring EGFR T790M. The treatment of one patient with advanced EGFR T790M-positive NSCLC was described as proof of principle. Moreover, we found that hyperphosphorylation of Ack1 and the subsequent activation of antiapoptotic signaling via the AKT pathway contributed to ASK120067 resistance. Concomitant targeting of EGFR and Ack1 effectively overrode the acquired resistance of ASK120067 both in vitro and in vivo. CONCLUSIONS: Our results idenfity ASK120067 as a promising third-generation EGFR inhibitor and reveal for the first time that Ack1 activation as a novel resistance mechanism to EGFR inhibitors that guide to potential combination strategy.

GZD824 as a FLT3, FGFR1 and PDGFRα Inhibitor Against Leukemia In Vitro and In Vivo.

GZD824 is a novel third-generation BCR-ABL inhibitor. It entered Phase II clinical trials in China and Phase Ib clinical trials in USA in 2019 for treatment of patients with resistant chronic myeloid leukemia (CML). We found that at concentrations below 10 nM, GZD824 significantly suppresses FLT3, FGFR1 and PDGFRα kinase activities and inhibits their signal pathways in MV4-11Flt3-ITD, KG-1FGFR1OP2-FGFR1 and EOL-1FIP1L1-PDGFRa leukemia cells. It selectively inhibits the growth of MV4-11Flt3-ITD, KG-1FGFR1OP2-FGFR1 and EOL-1FIP1L1-PDGFRa cells, and also effectively suppresses the growth of Ba/F3-FLT3-ITD cells harboring F691I and other mutations with IC50 values <10 nM. GZD824 induces G0/G1 phase arrest and apoptosis in MV4-11, KG-1 and EOL-1 cells and activates cleavage of caspase-3 and PARP. In MV4-11, Ba/F3-ITD-F691I and KG-1 mouse xenograft models, GZD824 at 10 or 20 mg/kg, q2d, p.o. almost completely eradicates tumors. It also inhibits the viability of primary leukemic blasts from a FLT3-ITD positive AML patient but not those expressing native FLT3. Thus GZD824 suppresses leukemia cells of FLT3-ITD-driven AML and other hematologic malignancies driven by FGFR1 or PDGFRa, and it may be considered to be a novel agent for the treatment of leukemia.

Quinolone antibiotic derivatives as new selective Axl kinase inhibitors.

Axl is a new promising molecular target for antineoplastic therapies. A series of quinolone antibiotic derivatives were designed and synthesized as new selective Axl inhibitors. One of the most promising compound 8i bound tightly to Axl with a Kd value of 1.1 nM, and inhibited its kinase activity with an IC50 value of 26 nM. The compound also significantly inhibited the phosphorylation of Axl and dose dependently inhibited cell invasion and migration in TGF-ß1 induced MDA-MD-231 breast cancer cells. In addition, 8i demonstrated reasonable pharmacokinetic properties and exhibited extraordinary target selectivity over 468 kinases except for Flt3 (IC50 = 50 nM)), with a S(10) and S(35) value of 0.022 and 0.42 at 1.0 µM, respectively. Compound 8i may serve as a new valuable lead compound for future anticancer drug discovery.

Discovery of JND3229 as a New EGFRC797S Mutant Inhibitor with In Vivo Monodrug Efficacy.

EGFRC797S mutation inducing resistance against third generation EGFR inhibitor drugs is an emerging "unmet clinical need" for nonsmall cell lung cancer patients. The pyrimidopyrimidinone derivative JND3229 was identified as a new highly potent EGFRC797S inhibitor with single digit nM potency. It also exhibited good in vitro and in vivo monodrug anticancer efficacy in a xenograft mouse model of BaF3/EGFR19D/T790M/C797S cells. A high-resolution X-ray crystallographic structure was also determined to elucidate the interactions between JND3229 and EGFRT790M/C797S. Our study provides an important structural and chemical basis for future development of new generation EGFRC797S inhibitors as anticancer drugs.

2,4-Diarylamino-pyrimidines as kinase inhibitors co-targeting IGF1R and EGFR(L858R/T79°M).

IGF1R amplification was recently implied to be related to the secondary acquired resistance against the 2nd or 3rd generation EGFR inhibitor therapies. We have successfully identified a series of 2,4-diarylamino-pyrimidines as new IGF1R/EGFR(L858R/T790M) co-targeting agents. One of the most promising compounds 8g potently inhibits both kinases with low nanomolar IC50 values, but is significantly less potent in inhibiting the wild type EGFR. The compound also displays a good kinase selectivity profile against a panel of 468 kinases. Moreover, 8g strongly suppresses the proliferation of CO-1686-resistant H1975-IGF1R cancer cells, suggesting its promising potential as a new lead compound for future anticancer drug discovery.