An exploration of solvent-front region high affinity moiety leading to novel potent ALK & ROS1 dual inhibitors with mutant-combating effects

Discovery of imidazo[1,2-b]pyridazine macrocyclic derivatives as novel ALK inhibitors capable of combating multiple resistant mutants

Anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitor (TKI) often loses effectiveness against non-small cell lung malignancies (NSCLCs) with ALK gene rearrangements (ALK⁺). 19 novel imidazo[1,2-b]pyridazine macrocyclic derivatives were designed, synthesized, and tested for their biological activities in an effort to develop ALK inhibitors that would overcome second-generation ALK-TKIs, particularly the G1202R mutation and the lorlatinib-resistant L1196M/G1202R double mutations. Of all the target substances, O-10 had the most effective enzymatic inhibitory activity, with IC₅₀ values for ALK^WT, ALK^G1202R, and ALK^{L1196M/G1202R} of 2.6, 6.4, and 23 nM, respectively. O-10, on the other hand, reduced the growth of ALK-positive Karpas299, BaF3-EML4-ALK^G1202R, and BaF3-EML4-ALK^{L1196M/G1202R} cells with IC₅₀ values of 38, 52, and 64 nM, respectively. This was equally effective to the reference drug Repotrectinib (IC₅₀ = 40, 164, and 208 nM). The kinase selectivity profile, liver microsome stability test and in vivo pharmacokinetic properties in SD rats of compound O-10 were further evaluated. O-10 was regarded as an effective ALK inhibitor for the treatment of mutations overall.

Discovery of novel phenyl triazole analogs as TRK/ALK dual inhibitors with prospective antitumor effects

The exploration of novel anaplastic lymphoma kinase (ALK) and tropomyosin receptor kinase (TRK) dual inhibitors tended to serve as targeted treatment of cancer. Herein, a series of phenyl triazole derivatives were designed and synthesized as ALK/TRK dual regulators based on structure-based drug design (SBDD) strategy and were evaluated for antiproliferative activity by MTT assay. Accordingly, all compounds showed surprising cytotoxicity with IC₅₀ values below 10 μM on KM12, H2228 and KARPAS299 cell lines. Among them, compound 13a bearing (2-(4-methylpiperazin-1-yl)phenyl)morpholinomethanone moiety was identified as the optimal hit in enzymatic screening with IC₅₀ values of 1.9 nM (TRKA), 7.2 nM (ALK) and 65.2 nM (ALK^L1196M), respectively. Furthermore, 13a could inhibit KM12 cell migration and colony formation in a dose dependent manner. Meanwhile, AO/EB staining indicated that the pro-apoptotic effect of 13a was comparable to that of Entrectinib at the dose of 200 nM. Ultimately, the binding model of 13a with TRKA and ALK well established its mode of action which accounted for the superior activities as a promising antitumor candidate.

Fragment-based discovery of novel phenyltriazolyl derivatives as allosteric type-I1/2 ALK inhibitors with promising antitumor effects

Based on the high-throughput screening hit BY-1, a series of phenyltriazolyl derivatives were developed. Satisfyingly, most compounds were detected moderate to excellent antitumor effects against Karpas299 and H2228 cells. Among them, 12k bearing 4‑hydroxypiperidinyl group exhibited the optimal activities against tested cells with IC₅₀ values of 51 nM and 175 nM, as well as promising inhibitory effects on ALK^WT (3.7 nM) and ALK^L1196M (6.8 nM). Unlike the conventional type-I ALK inhibitors, molecular models identified 12k as an allosteric type-I^1/2 inhibitor by forming key interactions in both the ATP binding region and the hydrophobic back pocket of ALK. Intriguingly, 12k could dose-dependently induce apoptosis on H2228 cell and inhibit colony formation and tumor cell migration. Taken together, the rationalization of 12k may shed new light on the identification of novel allosteric type-I^1/2 ALK inhibitors.

Structural and PK-guided identification of indole-based non-acidic autotaxin (ATX) inhibitors exhibiting high in vivo anti-fibrosis efficacy in rodent model

In recent decades, pharmacological targeting of the autotaxin (ATX)/lysophosphatidic acid (LPA) axis accounted for excellent disease management benefits. Herein, to extend the scope of structure-activity relationships (SARs), fifteen indole-based carbamate derivatives (1-15) were prepared to evaluate the ATX inhibitory potency. Among them, compound 4 bearing morpholine moiety was identified as the optimal ATX inhibitor (0.41 nM), superior to the positive control GLPG1690 (2.90 nM). To resolve the intractable issue of poor pharmacokinetic (PK) property, urea moiety was introduced as a surrogate of carbamate which furnished compounds 16-30. The dedicated modification identified the diethanolamine entity 30 with satisfactory water solubility and PK profiles with a minimum sacrifice of ATX inhibition (2.17 nM). The most promising candidate 30 was evaluated for anti-fibrosis effect in a bleomycin challenged mice lung fibrosis model. Upon treatment with 30, the in vivo ATX activity in both lung homogenate and broncheoalveolar fluid (BALF) sample was significantly down-regulated. Furthermore, the gene expression of pro-fibrotic cytokines transforming growth factor-β (TGF-β), interleukin- 6 (IL-6) and tumor necrosis factor-α (TNF-α) in lung tissue was reduced to normal level. Collectively, the promising biological effects may advocate potential application of 30 in fibrosis relevant diseases.

Discovery of novel 2-phenylamino-4-prolylpyrimidine derivatives as TRK/ALK dual inhibitors with promising antitumor effects

In order to explore novel TRK and ALK dual inhibitors, a series of 2-phenylamino-4-prolylpyrimidine derivatives were designed, synthesized and evaluated for their in vitro cytotoxicity and enzymatic activities. Delightfully, most compounds were detected moderated to excellent activities in cellular assay. Among them, compound 21 exhibited encouraging cytotoxicity on KM12, H2228 and KARPAS299 cells with IC₅₀ values of 0.86, 0.141 and 0.072 μM. Meanwhile, the performances of 21 in the enzymatic assays were in good accordance with anti-proliferative activity with IC₅₀ values of 2.2, 9.3 and 38 nM towards TRKA, ALK^WT and ALK^L1196M, respectively. Compared with Entrectinib, compound 21 not only ensured the inhibitory activity on TRKA, but also improved the affinity with ALK and ALK^L1196M to a certain extent. Ultimately, the binding model of 21 with TRKA and ALK were ideally established through molecular docking, which further confirmed the SARs analysis.

Fragment-based modification of 2,4-diarylaminopyrimidine derivatives as ALK and ROS1 dual inhibitors to overcome secondary mutants

In order to explore novel ALK and ROS1 dual inhibitors capable of overcoming crizotinib-resistant mutants, two series of 2,4-diarylaminopyrimidine derivatives were designed, synthesized and evaluated for their in vitro cytotoxic activity. In this work, we retained the 2,4-diarylaminopyrimidine scaffold and derivatize the DAAP scaffold with sulfonyl and acrylamide moieties to extend the structure-activity relationship (SAR) study. To our delight, some compounds exhibited excellent inhibitory activity with a double-digit nanomolar level in MTT assay. Four compounds were selected for enzymic assays further, the results led to the identification of a potent ALK and ROS1 dual inhibitor X-17, with IC₅₀ values of 3.7 nM, 2.3 nM, 8.9 nM and 1.9 nM against ALK, ALK^L1196M, ALK^G1202R and ROS1, respectively. Ultimately, the molecular docking studies on X-17 clearly disclosed reasonable and optimal binding interactions with ALK.

Structure-based linker exploration: Discovery of 1-ethyl-1H-indole analogs as novel ATX inhibitors

Aiming to develop novel ATX inhibitors, an indole-3-carboxylic acid lead Indole-1 was identified through high-throughput screening (HTS) efforts. The Indole-1 analogs 1-7 was firstly prepared which exerted mild activity comparable to Indole-1 (740 nM) in ATX enzyme assay. Further structural modification to identify type IV ATX inhibitors was proceeded through derivatization of the indole-3-carboxylic acid group. Resultantly, compounds 8-17 containing acyl hydrazone linker displayed poor activity (over 3.49 μM). Alternatively, replacing the acylhydrazone linker with urea counterpart by the amide bond reversal principle, the acquired compounds 18-22 achieved obvious improvements with submicromolar activities. Furthermore, with the aim to reducing cLogP, the thiazole ring of 18-22 was altered to the benzamide (23-32) with the urea linker unchanged. Remarkably, the benzamide derivative 24 with 4-hydroxy piperidine fragment was identified which exhibited prominent activity with IC₅₀ value of 2.3 nM. Especially, dedicated molecular docking study was throughout the modification process which qualified 24 as optimal entity in accordance with the ATX inhibitory results.