Activation of anaplastic lymphoma receptor tyrosine kinase (ALK) is involved in the pathogenesis of several carcinomas, including non-small cell lung cancer (NSCLC). Echinoderm microtubule-associated protein like 4 (EML4)-ALK, which is derived from the rearrangement of ALK and EML4 genes, has been validated as a therapeutic target in a subset of patients with NSCLC. Here, we investigated the effects of ASP3026, a novel small-molecule ALK inhibitor, against ALK-driven NSCLC. ASP3026 inhibited ALK activity in an ATPcompetitive manner and had an inhibitory spectrum that differed from that of crizotinib, a dual ALK/MET inhibitor. In mice xenografted with NCI-H2228 cells expressing EML4-ALK, orally administered ASP3026 was well absorbed in tumor tissues, reaching concentrations >10-fold higher than those in plasma, and induced tumor regression with a wide therapeutic margin between efficacious and toxic doses. In the same mouse model, ASP3026 enhanced the antitumor activities of paclitaxel and pemetrexed without affecting body weight. ASP3026 also showed potent antitumor activities, including tumor shrinkage to a nondetectable level, in hEML4-ALK transgenic mice and prolonged survival in mice with intrapleural NCI-H2228 xenografts. In an intrahepatic xenograft model using NCI-H2228 cells, ASP3026 induced continuous tumor regression, whereas mice treated with crizotinib showed tumor relapse after an initial response. Finally, ASP3026 exhibited potent antitumor activity against cells expressing EML4-ALK with a mutation in the gatekeeper position (L1196M) that confers crizotinib resistance. Taken together, these findings indicate that ASP3026 has potential efficacy for NSCLC and is expected to improve the therapeutic outcomes of patients with cancer with ALK abnormality.

First-and second-generation EGFR tyrosine kinase inhibitors (TKI) are effective clinical therapies for patients with nonsmall cell lung cancer (NSCLC) harboring EGFR-activating mutations. However, almost all patients develop resistance to these drugs. The EGFR T790M mutation of EGFR is the most predominant mechanism for resistance. In addition, activation of AXL signaling is one of the suggested alternative bypassing pathways for resistance to EGFR-TKIs. Here, we report that naquotinib, a pyrazine carboxamide-based EGFR-TKI, inhibited EGFR with activating mutations, as well as T790M resistance mutation while sparing wild-type (WT) EGFR. In in vivo murine xenograft models using cell lines and a patient-derived xenograft model, naquotinib induced tumor regression of NSCLC with EGFR-activating mutations with or without T790M resistance mutation, whereas it did not significantly inhibit WT EGFR signaling in skin. Furthermore, naquotinib suppressed tumor recurrence during the treatment period of 90 days. In addition, unlike erlotinib and osimertinib, naquotinib inhibited the phosphorylation of AXL and showed antitumor activity against PC-9 cells overexpressing AXL in vitro and in vivo. Our findings suggest that naquotinib has therapeutic potential in patients with NSCLC with EGFRactivating mutations, T790M resistance mutation, and AXL overexpression.

EML4-ALK is an oncogenic fusion kinase, which was first identified in non-small cell lung cancer (NSCLC), and is regarded as an attractive therapeutic target for treating a subpopulation of NSCLC patients. Crizotinib, which is inhibitor for MET and ALK, was recently approved by FDA (26 August 2011) for patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) that is anaplastic lymphoma kinase (ALK)-positive as detected by an FDA-approved test. We synthesized and screened chemical compounds utilizing an ALK kinase inhibition assay aimed at the EML4-ALK target for drug discovery, and found ASP3026, a novel and selective inhibitor for the ALK kinase. ASP3026 potently inhibited ALK kinase activity and was more selective than crizotinib in a Tyr-kinase panel. In an anchorage independent in vitro cell growth assay, ASP3026 inhibited the growth of NCI-H2228, a human NSCLC tumor cell line endogenously expressing EML4-ALK variant 3 and that of 3T3 cells expressing EML4-ALK variant 1, 2 and 3. The plasma and tumor concentrations of ASP3026 in mice xenografted with NCI-H2228 tumor were determined using high-performance liquid chromatography-tandem mass spectrometry. Significant tumor penetration was observed. The antitumor activities were evaluated using mice bearing subcutaneous NCI-H2228 tumor xenografts. ASP3026, (daily oral dosing for 14 days) induced dose dependent anti-tumor effects starting at 1 mg/kg with marked regression at 10, 30 and 100 mg/kg. Body weights were unaffected. Crizotinib, (twice daily oral dosing) was less potent, with growth inhibition at 10 mg/kg, and tumor regression at 30 mg/kg. A dose of 100 mg/kg of crizotinib was poorly tolerated. Resistance mutations in ALK kinase domain against crizotinib were reported following sequence analysis of tumor cells derived from crizotinib-relapsed patients. The position of the mutation is the so-called gatekeeper mutation and is thought to be one of the causes of crizotinib relapse. In an EML4-ALK driven tumor model with gatekeeper mutation, ASP3026 showed potent anti-tumor effects while crizotinib was ineffective even at 100 mg/gk qd. In summary, ASP3026 has a broad safety margin and inhibitory activity at the gatekeeper mutation. Therefore, ASP3026 may still effective in EML4-ALK fusion positive NSCLC patients, that have relapsed to crizotinib. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A227.

EML4-ALK is an oncogenic fusion kinase which was first identified in non-small cell lung cancer (NSCLC), and is regarded as an attractive therapeutic target for treating a subpopulation of NSCLC patients. We synthesized and screened chemical compounds utilizing an ALK kinase inhibition assay aimed at the EML4-ALK target for drug discovery, and found ASP3026, a novel and selective inhibitor for the ALK kinase. ASP3026 inhibited ALK kinase activity at an IC50 value of 3.5 nmol/L, and showed more selective ALK inhibition in a Tyr-kinase panel than PF02341066. In an anchorage independent in vitro cell growth assay, ASP3026 inhibited the growth of NCI-H2228, a human NSCLC tumor cell line endogenously expressing EML4-ALK variant 3, with an IC50 value of 64.8 nmol/L. This growth inhibition was accompanied with the decrease in phosphorylation of EML4-ALK protein, indicating that ASP3026 exerts its anti-proliferative activity through ALK kinase inhibition. The plasma and tumor concentrations of ASP3026 in mice xenografted with NCI-H2228 tumor after a 5-day repeated oral dosing of ASP3026 (10 mg/kg once daily) were determined using high-performance liquid chromatography-tandem mass spectrometry. Tmax values were 4 h in plasma and tumors. Cmax values at the corresponding doses were, respectively, 875 nmol/mL and 15500 nmol/g. A decrease of phophorylated EML4-ALK was confirmed 4 hours after a single administration of ASP3026 at 10 mg/kg by Western-blot analysis. The antitumor activities were evaluated using mice bearing subcutaneous NCI-H2228 tumor xenografts. ASP3026, administered as twice daily oral dosing for 14 days, induced dose dependent anti-tumor effects starting at 1 mg/kg with strong regression at 10, 30 and 100 mg/kg. No influence on body weights was observed in all dose range of ASP3026 treated-mice. In contrast, PF02341066 at twice daily oral dosing resulted in growth inhibition of NCI-H2228 xenografted tumors at 10 mg/kg, and tumor regression at 30 mg/kg. In addition, 100 mg/kg of PF02341066 was intolerable in this model. These results suggest that ASP3026 is a novel and selective ALK inhibitor, which is orally active, and will possibly target NSCLC patients possessing the EML4-ALK fusion. We are starting phase I clinical trials of ASP3026 in the near future. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2821. doi:10.1158/1538-7445.AM2011-2821

BACKGROUND: Reversible EGFR TKIs, gefitinib and erlotinib, have shown antitumor efficacy in NSCLC patients with activating mutations in EGFR kinase domain. But the clinical efficacy of these agents is limited by the development of acquired drug resistance, which is most commonly caused by T790M resistance mutation in EGFR. This mutation has been detected in approximately 50% to 60% of patients. The 2nd generation irreversible EGFR inhibitors inhibit EGFR with T790M, but their clinical efficacy to NSCLC patients with T790M appears to be limited due to severe adverse effects caused by concomitant WT EGFR inhibition. Therefore, an EGFR TKI which inhibits T790M mutant EGFR selectively with less activity against WT EGFR may be beneficial. Here we report ASP8273, a novel, small molecule EGFR TKI that inhibits the kinase activity of EGFR containing the activating and T790M resistance mutations with less activity against WT EGFR. METHODS: The inhibitory effect and the selectivity of ASP8273 were evaluated against mutant EGFR (L858R, del ex19, L858R/T790M and del ex19/T790M) and WT EGFR using in vitro enzymatic and cell-based assay. Binding mode of ASP8273 to EGFR was assessed by mass spectrometry. Antitumor activity of ASP8273 was evaluated in xenograft models using PC-9 (del ex19), HCC827 (del ex19), NCI-H1975 (L858R/T790M) and PC-9ER (Erlotinib Resistant)(del ex19/T790M) NSCLC cells. RESULTS: ASP8273 inhibited mutant EGFR containing del ex19 or L858R activating mutations as well as the T790M resistance mutation with lower IC50 values than WT EGFR. Mass spectrometry analysis revealed that ASP8273 is covalently bound to a mutant EGFR(L858R/T790M) via C797 in the kinase domain of EGFR. In NCI-H1975 cells, ASP8273 induced long-lasting inhibition of EGFR phosphorylation for 24 h after washout of compound. In assays using endogenously EGFR-dependent cells, ASP8273 inhibited the growth of PC-9(del ex19), HCC827(del ex19), NCI-H1975(del ex19/T790M) and PC-9ER(del ex19/T790M) with IC50 values of 8-33 nM, more potently than that of NCI-H1666(WT) with IC50 value of 230 nM. In mouse xenograft studies, ASP8273 induced tumor regression in NCI-H1975 (L858R/T790M), HCC827 (del ex19) and PC-9 (del ex19) xenograft models by repeated oral dosing in a dose-dependent manner. Dosing schedules did not affect the efficacy of ASP8273. In an NCI-H1975 xenograft model, complete regression of tumor was achieved after 14-days of ASP8273 treatment. Complete regression was maintained in 50% of mice more than 85 days after cessation of ASP8273 treatment. CONCLUSIONS: ASP8273 inhibits the growth of NSCLC cells with EGFR activating and T790M resistance mutations with evidence of tumor regression. Therefore, ASP8273 may show therapeutic efficacy in NSCLC patients with EGFR mutations. Clinical trials of ASP8273 in NSCLC patients are planned in the US/EU and Asia. Citation Format: Hideki Sakagami, Satoshi Konagai, Hiroko Yamamoto, Hiroaki Tanaka, Takahiro Matsuya, Masamichi Mori, Hiroyuki Koshio, Masatoshi Yuri, Masaaki Hirano, Sadao Kuromitsu. ASP8273, a novel mutant-selective irreversible EGFR inhibitor, inhibits growth of non-small cell lung cancer (NSCLC) cells with EGFR activating and T790M resistance mutations. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1728. doi:10.1158/1538-7445.AM2014-1728