Osamu Kondoh

Antitumor activity of the selective ALK inhibitor alectinib in models of intracranial metastases

PurposeThe clinical efficacy of the anaplastic lymphoma kinase (ALK) inhibitor crizotinib has been demonstrated in ALK fusion-positive non-small cell lung cancer (NSCLC); however, brain metastases are frequent sites of initial failure in patients due to poor penetration of the central nervous system by crizotinib. Here, we examined the efficacy of a selective ALK inhibitor alectinib/CH5424802 in preclinical models of intracranial tumors.MethodsWe established intracranial tumor implantation mouse models of EML4–ALK-positive NSCLC NCI-H2228 and examined the antitumor activity of alectinib in this model. Plasma distribution and brain distribution of alectinib were examined by quantitative whole-body autoradiography administrating a single oral dose of 14C-labeled alectinib to rats. The drug permeability of alectinib was evaluated in Caco-2 cell.ResultsAlectinib resulted in regression of NCI-H2228 tumor in mouse brain and provided a survival benefit. In a pharmacokinetic study using rats, alectinib showed a high brain-to-plasma ratio, and in an in vitro drug permeability study using Caco-2 cells, alectinib was not transported by P-glycoprotein efflux transporter that is a key factor in blood–brain barrier penetration.ConclusionsWe established intracranial tumor implantation models of EML4–ALK-positive NSCLC. Alectinib showed potent efficacy against intracranial EML4–ALK-positive tumor. These results demonstrated that alectinib might provide therapeutic opportunities for crizotinib-treated patients with brain metastases.

Selective ALK inhibitor alectinib with potent antitumor activity in models of crizotinib resistance

The clinical efficacy of the ALK inhibitor crizotinib has been demonstrated in ALK fusion-positive NSCLC; however, resistance to crizotinib certainly occurs through ALK secondary mutations in clinical use. Here we examined the efficacy of a selective ALK inhibitor alectinib/CH5424802 in models of crizotinib resistance. Alectinib led to tumor size reduction in EML4-ALK-positive xenograft tumors that failed to regress fully during the treatment with crizotinib. In addition, alectinib inhibited the growth of some EML4-ALK mutant-driven tumors, including the G1269A model. These results demonstrated that alectinib might provide therapeutic opportunities for crizotinib-treated patients with ALK secondary mutations.

Alectinib Shows Potent Antitumor Activity against RET-Rearranged Non–Small Cell Lung Cancer

Alectinib/CH5424802 is a known inhibitor of anaplastic lymphoma kinase (ALK) and is being evaluated in clinical trials for the treatment of ALK fusion–positive non–small cell lung cancer (NSCLC). Recently, some RET and ROS1 fusion genes have been implicated as driver oncogenes in NSCLC and have become molecular targets for antitumor agents. This study aims to explore additional target indications of alectinib by testing its ability to inhibit the activity of kinases other than ALK. We newly verified that alectinib inhibited RET kinase activity and the growth of RET fusion–positive cells by suppressing RET phosphorylation. In contrast, alectinib hardly inhibited ROS1 kinase activity unlike other ALK/ROS1 inhibitors such as crizotinib and LDK378. It also showed antitumor activity in mouse models of tumors driven by the RET fusion. In addition, alectinib showed kinase inhibitory activity against RET gatekeeper mutations (RET V804L and V804M) and blocked cell growth driven by the KIF5B-RET V804L and V804M. Our results suggest that alectinib is effective against RET fusion–positive tumors. Thus, alectinib might be a therapeutic option for patients with RET fusion–positive NSCLC. Mol Cancer Ther; 13(12); 2910–8. ©2014 AACR.

Discovery and biological activity of a novel class I PI3K inhibitor, CH5132799

Phosphatidylinositol 3-kinase (PI3K) is a lipid kinase and a promising therapeutic target for cancer. Using structure-based drug design (SBDD), we have identified novel PI3K inhibitors with a dihydropyrrolopyrimidine skeleton. Metabolic stability of the first lead series was drastically improved by replacing phenol with aminopyrimidine moiety. CH5132799, a novel class I PI3K inhibitor, exhibited a strong inhibitory activity especially against PI3Kα (IC(50)=0.014 μM). In human tumor cell lines with PI3K pathway activation, CH5132799 showed potent antiproliferative activity. CH5132799 is orally available and showed significant antitumor activity in PI3K pathway-activated human cancer xenograft models in mice.

Synthesis and structure-activity relationships of novel benzofuran farnesyltransferase inhibitors.

A series of benzofuran-based farnesyltransferase inhibitors have been designed and synthesized as antitumor agents. Among them, 11f showed the most potent enzyme inhibitory activity (IC(50)=1.1nM) and antitumor activity in human cancer xenografts in mice.

Phosphoproteomic analysis of distinct tumor cell lines in response to nocodazole treatment

Here, we report for the first time a comparative phosphoproteomic analysis of distinct tumor cell lines in the presence or absence of the microtubule‐interfering agent nocodazole. In total, 1525 phosphorylation sites assigned to 726 phosphoproteins were identified using LC‐MS‐based technology following phosphopeptide enrichment. Analysis of the amino acid composition surrounding the identified in vivo phosphorylation sites revealed that they could be classified into two motif groups: pSer‐Pro and pSer‐Asp/Glu. Phosphoproteomic change resulting from nocodazole treatment varied among cell lines in terms of the numbers of total phosphopeptides identified, motif groups, and functional annotation groups; however, the cell lines were equally sensitive to nocodazole. The identified phosphoproteome subset contained major signaling proteins and proteins known to be involved in mitosis, but did not always exhibit the same changes in the tumor cells from nocodazole treatment. In spite of the complex changes observed in the phosphorylation of many of the proteins, possible common features induced by nocodazole were found, including phosphorylation of nucleophosmin (NPM) S254 and coatomer protein complex, subunit α (COPA) S173, suggesting that the events are not cell‐type specific but events generally occurring in mitosis or induced by a microtubule‐interfering agent. Further, temporal analysis of phosphoproteome change revealed that phosphorylation of NPM S254 and COPA S173 was observed from the early (6 h) and late (24 h) time point after nocodazole treatment, respectively, suggesting that NPM S254 may be involved in the induction of M‐phase arrest by nocodazole, whereas COPA S173 may be caused as a result of M‐phase arrest.

Enhanced antitumor activity of erlotinib in combination with the Hsp90 inhibitor CH5164840 against non-small-cell lung cancer

Inhibition of heat shock protein 90 (Hsp90) can lead to degradation of multiple client proteins, which are involved in tumor progression. Epidermal growth factor receptor (EGFR) is one of the most potent oncogenic client proteins of Hsp90. Targeted inhibition of EGFR has shown clinical efficacy in the treatment of patients with non‐small‐cell lung cancer (NSCLC). However, primary and acquired resistance to the existing EGFR inhibitors is a major clinical problem. In the present study, we investigated the effect of the novel Hsp90 inhibitor CH5164840 on the antitumor activity of erlotinib. The NSCLC cell lines and xenograft models were treated with CH5164840 and erlotinib to examine their mechanisms of action and cell growth inhibition. We found that CH5164840 showed remarkable antitumor activity against NSCLC cell lines and xenograft models. The addition of CH5164840 enhanced the antitumor activity of erlotinib against NCI‐H292 EGFR‐overexpressing xenograft models. Phosphorylation of Stat3 increased with erlotinib treatment in NCI‐H292 cells, which was abrogated by Hsp90 inhibition. Furthermore, in a NCI‐H1975 T790M mutation erlotinib‐resistant model, CH5164840 enhanced the antitumor activity of erlotinib despite the low efficacy of erlotinib treatment alone. In addition, ERK signaling was effectively suppressed by combination treatment with erlotinib and CH5164840 in a NCI‐H1975 erlotinib‐resistant model. Taken together, these data indicate that CH5164840 has potent antitumor activity and is highly effective in combination with erlotinib against NSCLC tumors with EGFR overexpression and mutations. Our results support the therapeutic potential of CH5164840 as a Hsp90 inhibitor for combination therapy with EGFR‐targeting agents against EGFR‐addicted NSCLC.

Abstract 754: Selective ALK inhibitor alectinib (CH5424802/RO5424802) with potent antitumor activity in models of crizotinib resistance, including intracranial metastases

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Purpose: EML4-ALK has been implicated as a driver oncogene and a therapeutic target in non-small cell lung cancer (NSCLC). The clinical efficacy of the ALK inhibitor crizotinib has been demonstrated in ALK fusion-positive NSCLC; however, resistance to crizotinib certainly occurs through ALK secondary mutations in clinical use. In addition, brain metastases are frequent sites of initial failure in patients because crizotinib has poor penetration of the central nervous system. This study aimed to clarify the efficacy of ALK inhibitor alectinib (CH5424802/RO5424802) in models of crizotinib-resistant ALK mutant tumors and intracranial tumors. Experimental Design: The antitumor activity of alectinib was evaluated in subcutaneous xenograft tumor models of Ba/F3 cells expressing mutated EML4-ALK, and in intracranial tumor implantation models of EML4-ALK-positive NSCLC NCI-H2228. Results: Alectinib had kinase inhibitory activity against some ALK mutations, including G1269A, and blocked tumor growth driven by a mutant of EML4-ALK in vitro and in vivo. In intracranial tumor implantation mouse models, alectinib resulted in regression of NCI-H2228 tumor in brain and provided a survival benefit. Alectinib is not a substrate for P-glycoprotein efflux transporter in vitro and showed a high brain-to-plasma ratio in rat. Additionally, alectinib led to tumor size reduction in the subcutaneous NCI-H2228 xenograft tumor that had failed to regress fully during treatment with crizotinib. Conclusions: Alectinib was effective against most EML4-ALK mutations and showed potent efficacy against intracranial ALK-positive tumor. Thus, alectinib might provide therapeutic opportunities for crizotinib-treated patients with ALK secondary mutations and brain metastases. Citation Format: Tatsushi Kodama, Toshiyuki Tsukaguchi, Masami Hasegawa, Miyuki Yoshida, Kenji Takanashi, Osamu Kondoh, Hiroshi Sakamoto. Selective ALK inhibitor alectinib (CH5424802/RO5424802) with potent antitumor activity in models of crizotinib resistance, including intracranial metastases. [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 754. doi:10.1158/1538-7445.AM2014-754

Abstract 773: Alectinib shows potent antitumor activity against both ALK- and RET-rearranged non-small cell lung cancers

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA We have shown that alectinib is a potent ALK inhibitor and is being evaluated in clinical trials for the treatment of ALK fusion-positive non-small cell lung cancer (NSCLC). Recently, RET and ROS1 fusion genes have been implicated as driver oncogenes in 1-2% of NSCLC and have been developed into promising molecular targets for antitumor agents. Here, we investigate the additional target indication of alectinib by testing its ability to inhibit the activity of RET and ROS1 kinases. In enzyme assay, alectinib showed kinase inhibitory activity against RET as wells as ALK but did not show against ROS1. Alectinib inhibited the growth of LC-2/ad cells harboring CCDC6-RET and Ba/F3 cells expressing KIF5B-RET by suppressing RET phosphorylation. Alectinib also showed antitumor activity in mouse models of RET fusion-positive tumors (LC-2/ad cells and Ba/F3 cells expressing KIF5B-RET) and of ALK fusion-positive tumors (NCI-H2228 cells harboring EML4-ALK). In addition, alectinib showed kinase inhibitory activity against RET gatekeeper mutations (RET V804L and V804M) and blocked KIF5B-RET gatekeeper mutation-driven cell growth. Our results suggest that alectinib is effective against RET fusion-positive tumors, as observed in ALK fusion-positive tumors. Thus, alectinib might be a therapeutic option for patients with RET fusion-positive NSCLC. Citation Format: Tatsushi Kodama, Toshiyuki Tsukaguchi, Yasuko Satoh, Miyuki Yoshida, Yoshiaki Watanabe, Osamu Kondoh, Hiroshi Sakamoto. Alectinib shows potent antitumor activity against both ALK- and RET-rearranged non-small cell lung cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 773. doi:10.1158/1538-7445.AM2015-773

Abstract B157: Selective class I PI3K inhibitor CH5132799 induces significant tumor regression with suppressing 4E-BP1 phosphorylation.

The phosphatidylinositol 3-kinase (PI3K) pathway plays a central role in cell proliferation and survival in human cancer. Mutations of the PIK3CA gene, which encodes the class I PI3K catalytic subunit p110, are found in many cancer patients and activate the PI3K pathway, resulting in cancer development and progression. We previously identified CH5132799 as a novel inhibitor, selective to class I PI3K and with potent antitumor activity against tumors harboring PIK3CA mutations. Here we investigated the relationship between in vivo efficacy and PI3K signaling inhibition. CH5132799 suppressed tumor growth in a wide variety of xenograft models with PI3K pathway activation, including those with PIK3CA mutations. CH5132799 has two modes of tumor growth inhibition, tumor regression and tumor stasis. On the one hand, in the breast cancer xenograft models harboring PIK3CA mutations (KPL-4 and BT-474), CH5132799 induced remarkable tumor regression and also shrank the tumor of PTEN-deleted prostate cancer GXF-97 (‘tumor regression models’). On the other hand, in colorectal cancers with both PIK3CA and KRAS mutations (HCT116 and HCT15), CH5132799 treatment resulted in tumor stasis but did not induce tumor regression (‘tumor stasis models’). We analyzed PI3K and MAPK signaling in these xenograft tumors to explore the factors which could explain the tumor growth inhibition modes of CH5132799, tumor regression or stasis. Phosphorylation of Akt and S6 was inhibited by CH5132799 administration in all the tested tumors but ERK phosphorylation was not. Notably, 4E-BP1 phosphorylation (p-4E-BP1) was well suppressed in the tumor regression models but was only partially decreased in the tumor stasis models. These findings suggest that p-4E-BP1 determines whether CH5132799 induces tumor regression or stasis. Since p-4E-BP1 is known to be regulated by both PI3K and MAPK pathways, we examined the effects on p-4E-BP1 of combining inhibitors selective to each pathway: CH5132799 and RO4987655, an allosteric MEK inhibitor. Compared to their effect as single agents, the combined inhibitors drastically suppressed p-4E-BP1 in HCT116 cells in vitro, leading to potent growth inhibition and apoptosis induction. Furthermore, combining CH5132799 and RO4987655 induced remarkable in vivo tumor regression even in the HCT116 tumor stasis model, confirming the significance of p-4E-BP1 suppression in CH5132799-induced tumor regression. In conclusion, tumor regression or stasis induced by CH5132799 correlated with p-4E-BP1 being suppressed in the tumors. Moreover, in the model in which CH5132799 alone had induced tumor stasis with partial p-4E-BP1 suppression, combination with the MEK inhibitor achieved p-4E-BP1 suppression and tumor regression. From these lines of preclinical evidence, p-4E-BP1 suppression could also be a determinant factor of the CH5132799 response in clinical settings, and combination therapy with MEK inhibitors is a promising strategy to enhance CH5132799 efficacy. 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 B157.