A molecular glue RBM39-degrader induces synthetic lethality in cancer cells with homologous recombination repair deficiency

E7820 and Indisulam (E7070) are sulfonamide molecular glues that modulate RNA splicing by degrading the splicing factor RBM39 via ternary complex formation with the E3 ligase adaptor DCAF15. To identify biomarkers of the antitumor efficacy of E7820, we treated patient-derived xenograft (PDX) mouse models established from 42 patients with solid tumors. The overall response rate was 38.1% (16 PDXs), and tumor regression was observed across various tumor types. Exome sequencing of the PDX genome revealed that loss-of-function mutations in genes of the homologous recombination repair (HRR) system, such as ATM, were significantly enriched in tumors that responded to E7820 (p = 4.5 × 103). Interestingly, E7820-mediated double-strand breaks in DNA were increased in tumors with BRCA2 dysfunction, and knockdown of BRCA1/2 transcripts or knockout of ATM, ATR, or BAP1 sensitized cancer cells to E7820. Transcriptomic analyses revealed that E7820 treatment resulted in the intron retention of mRNAs and decreased transcription, especially for HRR genes. This induced HRR malfunction probably leads to the synthetic lethality of tumor cells with homologous recombination deficiency (HRD). Furthermore, E7820, in combination with olaparib, exerted a synergistic effect, and E7820 was even effective in an olaparib-resistant cell line. In conclusion, HRD is a promising predictive biomarker of E7820 efficacy and has a high potential to improve the prognosis of patients with HRD-positive cancers.

Ten-Gram-Scale Total Synthesis of the Anticancer Drug Candidate E7130 to Supply Clinical Trials

E7130 is a novel drug candidate with an exceedingly complex chemical structure of the halichondrin class, discovered by a total synthesis approach through joint research between the Kishi group at Harvard University and Eisai. Only 18 months after completion of the initial milligram-scale synthesis, ten-gram-scale synthesis of E7130 was achieved, providing the first good manufacturing practice (GMP) batch to supply clinical trials. This paper highlights the challenges in developing ten-gram-scale synthesis from the milligram-scale synthesis.

NF-κB suppression synergizes with E7386, an inhibitor of CBP/β-catenin interaction, to block proliferation of patient-derived colon cancer spheroids

Dysregulated activation of the WNT/β-catenin signaling pathway is essential for the initiation and development of various cancers. E7386, a small-molecule compound, attenuates WNT signaling by blocking the interaction between β-catenin and CREB-binding protein (CBP); hence, it is regarded as a therapeutic candidate for cancers with activated WNT signaling. In the present study, we evaluated the biological characteristics associated with E7386 sensitivity by using a panel of patient-derived colon cancer spheroids. An integrative approach that combined E7386 sensitivity and gene expression profiles revealed that the resistance of the cancer spheroids to E7386 was associated with the activation of the NF-κB pathway. NF-κB pathway inhibitors acted synergistically with E7386 to block proliferation and induce cell cycle arrest in E7386-resistant spheroids. These findings suggest a possibility that a combination of E7386 and NF-κB inhibition may effectively block the proliferation of a subset of colon cancer cells.

E7386, a Selective Inhibitor of the Interaction between β-Catenin and CBP, Exerts Antitumor Activity in Tumor Models with Activated Canonical Wnt Signaling

The Wnt/β-catenin signaling pathway plays crucial roles in embryonic development and the development of multiple types of cancer, and its aberrant activation provides cancer cells with escape mechanisms from immune checkpoint inhibitors. E7386, an orally active selective inhibitor of the interaction between β-catenin and CREB binding protein, which is part of the Wnt/β-catenin signaling pathway, disrupts the Wnt/β-catenin signaling pathway in HEK293 and adenomatous polyposis coli (APC)-mutated human gastric cancer ECC10 cells. It also inhibited tumor growth in an ECC10 xenograft model and suppressed polyp formation in the intestinal tract of Apc^{Min /+} mice, in which mutation of Apc activates the Wnt/β-catenin signaling pathway. E7386 demonstrated antitumor activity against mouse mammary tumors developed in mouse mammary tumor virus (MMTV)-Wnt1 transgenic mice. Gene expression profiling using RNA sequencing data of MMTV-Wnt1 tumor tissue from mice treated with E7386 showed that E7386 downregulated genes in the hypoxia signaling pathway and immune responses related to the CCL2, and IHC analysis showed that E7386 induced infiltration of CD8⁺ cells into tumor tissues. Furthermore, E7386 showed synergistic antitumor activity against MMTV-Wnt1 tumor in combination with anti-PD-1 antibody. In conclusion, E7386 demonstrates clear antitumor activity via modulation of the Wnt/β-catenin signaling pathway and alteration of the tumor and immune microenvironments, and its antitumor activity can be enhanced in combination with anti-PD-1 antibody. SIGNIFICANCE: These findings demonstrate that the novel anticancer agent, E7386, modulates Wnt/β-catenin signaling, altering the tumor immune microenvironment and exhibiting synergistic antitumor activity in combination with anti-PD-1 antibody.

Abstract 5940: Inhibition of β-catenin/CBP signaling alters EGFR fucosylation status in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy in the world with oral squamous cell carcinomas (OSCC) accounting for the majority of HNSCC cases. A major driver of OSCC is the epidermal growth factor receptor (EGFR), a receptor tyrosine kinase (RTK) with 12 N-glycosylation sites. Fucosylated N-linked glycans on EGFR are associated with survival e.g., they suppress receptor dimerization and signaling. High levels of fucosylated glycan epitopes have been observed in OSCC, where invasive regions lose expression of linkage-specific fucosylated epitopes, suggesting that fucosylated glycans are involved in the suppression of cell growth and invasion. Previously, it was shown that inhibition of the interaction between nuclear β-catenin and CREB-binding protein (CBP) in human OSCC cells and in mouse tumor xenografts with a small molecule inhibitor ICG-001, interfered with OSCC proliferation and aggressive features in cellular, zebrafish, and murine models. E7386, a novel β-catenin/CBP modulator displays activity profile that closely overlaps with that of ICG-001 and exhibits ~50 - 100-fold lower EC50 values. Treatment with ICG-001 and E7386, increased expression of two glycosyltransferases, FUT2 and FUT3 coincident with decreased EGFR abundance that was accompanied by higher fucosylation of EGFR and upregulated expression of E-cadherin and junctional β-catenin. Further, genomic analyses showed a positive correlation between the ICG-001 and E7386 treatments and EGFR inhibition, suggesting that higher expression of antennary fucosyltransferase genes suppresses EGFR signaling. We now show using nLC-MS/MS analyses that EGFR from metastatic HSC-3 cells had low levels of fucosylated N-glycans, while EGFR from indolent CAL27 cells displayed higher levels of fucosylation at multiple EGFR N-linked glycosylation sites, and that these changes were statistically significant. In-depth characterization of multiply-fucosylated N-glycans via tandem mass spectrometry of EGFR glycopeptides revealed new insights into the identity of fucosylated glycan epitopes. Collectively, these results suggest that the β-catenin/CBP axis promotes EGFR signaling through downregulation of fucosyltransferase expression and activity. We conclude that inhibition of β-catenin/CBP signaling with a novel small molecule E7386 may serve as a therapeutic approach to downregulate EGFR pro-tumorigenic activity in HNSCC patients.

Citation Format: Kevin B. Chandler, Khalid Alamoud, Bac-Cuc Nguyen, Vanessa L. Stahl, Takashi Owa, Kenichi Nomoto, Stefano Monti, Maria A. Kukuruzinska, Catherine E. Costello. Inhibition of β-catenin/CBP signaling alters EGFR fucosylation status in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5940.

Abstract 6566: Defining the effects of inhibiting the beta-catenin-CBP signaling axis with the small molecule E7386 by integrative analysis of omics data

Head and neck squamous cell carcinoma (HNSCC) is associated with high morbidity, poor survival rates, and limited treatment options. We previously reported that aberrant activation of nuclear β-catenin/cAMP-responsive element binding (CREB)-binding protein (CBP) signaling in primary HNSCC tumors was associated with progression to advanced disease and poor patient survival. Further, inhibition of β-catenin-CBP interaction with the first-generation inhibitor, ICG-001, greatly attenuated aggressive properties of HNSCC cells and tumor growth and metastases in murine and zebrafish models. Our recent findings show that a novel β-catenin/CBP modulator, E7386, displays an activity profile that closely overlaps with that of ICG-001, but exhibits ~50-100-fold lower EC50 values.

In this study, we used a novel method for gene regulatory network (GRN) reconstruction which analyzes publicly available high-throughput transcriptomics data from HNSCC to further elucidate the mechanisms of β-catenin-CBP inhibition by E7386. A Bayesian framework was used to reconstruct high-dimensional GRNs using constraint-based and shared structure learning from bulk RNA-seq data from TCGA. HNSCC patients were grouped into two subtypes, based on their “high” vs. “low” response to E7386 inhibition as predicted by the activation - or enrichment by Gene Set Variation Analysis (GSVA) - of the transcriptional signature we derived.

GRNs for the two subtypes were built, and their comparison highlighted new interactions in the “high” responders network between the β-catenin/CBP network and genes associated with histone modifications (ASH1L) and amino acid metabolism (MTR) concomitant with loss of interactions with regulators of cell cycle (ERCC6L) and protein secretion (SCAMP1) identified in the “low” responders network. Additionally, Kaplan-Meier survival plots showed that HNSCC patients with high activation of the E7386 signature had a significantly lower probability of survival. These results suggest that our GRN-based approach represents an important novel tool for assessing changes in regulatory network interactions in HNSCC and cancer.

Citation Format: Anthony Federico, Takashi Owa, Kenichi Nomoto, Xaralabos Varelas, Maria Kukuruzinksa, Stefano Monti. Defining the effects of inhibiting the beta-catenin-CBP signaling axis with the small molecule E7386 by integrative analysis of omics data [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6566.

Abstract 4179: E7130 derived from total synthesis of halichondrin as a novel tumor-microenvironment ameliorator

Background and objectives: Natural products have been a rich source of inspiration for drug discovery as demonstrated by the fact that over one-third of current therapeutic agents are natural products or compounds derived from them. Particularly, when the supply of a natural product from the natural source is limited, organic synthesis can offer a solution. However, with increasing structural complexity, this approach becomes exponentially more challenging, as a synthesis must meet various requirements, including high overall efficiency, scalability, cost-effectiveness, and product purity as well as conforming to good manufacturing practice (GMP) regulations. Despite the outstanding in vivo antitumor activity in mice, the limited supply from the natural sources has prevented drug development based on intact halichondrins.

Methods: We successfully synthesized 19.5 g of C52-halichondrin-B alcohol with 99.84% purity via a total synthesis. From 15.0 g of this material, we obtained 11.5 g of C52-halichondrin-B amine (E7130) with 99.81% purity under GMP conditions. With totally synthetic E7130, a novel microtubule dynamics inhibitor, we studied the activities in both of in vitro and in vivo. The inhibitory activity of E7130 towards tubulin polymerization was analyzed in the cell-free system in which tubulin polymerization could be monitored by fluorescence enhancement due to the incorporation of a fluorescence reporter into the microtubules during polymerization. We analyzed in vivo antitumor activities using both a human cancer cell line orthotopic transplantation mouse model and subcutaneous xenograft models. The immunohistochemical analyses were performed with tumor tissues collected from mouse models to analyze histological changes after treatment with E7130.

Results: E7130 is a novel microtubule dynamics inhibitor with exceedingly potent in vitro and in vivo anticancer activities. Significantly, E7130 not only is cytotoxic, but can also increase CD31-positive endothelial cells in tumors and reduce α-SMA-positive cancer-associated fibroblasts at pharmacologically relevant compound concentrations. Notably, this dual activity has been recognized for the first time through this study. According to these unique tumor microenvironment ameliorative effects, E7130 can augment the effect of other antitumor treatments in mouse models. In particular, a dose of 90 µg/kg, one-half of the maximum tolerated dose in mice, showed a prominent combinational effect with cetuximab, which suggests that E7130 has a different mechanism than other microtubule-targeted drugs.

Conclusions: E7130 ameliorates the tumor microenvironment to improve cancer treatment when used in combination with other compounds. The data provide compelling evidence that E7130 is a promising molecular-targeting anticancer agent.

Citation Format: Satoshi Kawano, Takanori Abe, Ken Ito, Kenzo Yahata, Kazunobu Kira, Tsuyoshi Akagi, Makoto Asano, Kentaro Iso, Yuki Sato, Fumiyoshi Matsuura, Isao Ohashi, Yasunobu Matsumoto, Minetaka Isomura, Takeo Sasaki, Takashi Fukuyama, Yusuke Miyashita, Yosuke Kaburagi, Akira Yokoi, Osamu Asano, Takashi Owa, Yoshito Kishi. E7130 derived from total synthesis of halichondrin as a novel tumor-microenvironment ameliorator [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4179.

Abstract 4183: Mechanism of action analysis of anti-CAF activity of E7130, a novel tumor-microenvironment ameliorator

Background and objectives: Despite the outstanding antitumor activity of halichondrins in mice, the limited supply from the natural sources has prevented drug development using intact halichondrins. We achieved a total synthesis of C52-halichondrin-B amine (E7130) under good manufacturing practice (GMP) conditions. E7130 is not only a novel microtubule dynamics inhibitor, but also a novel tumor-microenvironment ameliorator. E7130 can increase intratumoral CD31-positive endothelial cells and reduce α-SMA-positive cancer-associated fibroblasts (CAFs) at pharmacologically relevant compound concentrations. Here, we analyzed the molecular mechanisms of the α-SMA-positive CAF reduction with E7130.

Methods: The expression levels of α-SMA, ECM proteins, ER-TR7 (pan-fibroblast marker), and Ki67 were examined using E7130-treated tumors. In vitro co-culture experiments, normal human fibroblasts were co-cultured with human cancer cells. To examine the effects of E7130 on the TGF-β-induced CAF activation, normal human fibroblasts were treated with TGF-β (final concentration of 1 ng/mL) and E7130 at the several concentrations, and gene expression analysis and immunocytochemical analysis were conducted.

Results: E7130 reduced α-SMA-positive CAF and malignant ECM proteins without changing total fibroblast number in tumors. The in vitro co-culture system revealed that TGF-β from cancer cells activate normal human fibroblast and increased α-SMA expression. In addition, treatment with E7130 interfered with α-SMA induction by TGF-β in fibroblasts without growth inhibitory activity. We further found that E7130 inhibited TGF-β-induced PI3K/AKT/mTOR pathway, which resulted in the reduction of α-SMA expression in fibroblasts. Moreover, TGF-β treatment enhanced β-tubulin expression and focal adhesions formation, which were diminished by co-treatment with E7130 in fibroblasts. Many signaling complexes are assembled in focal adhesion sites, and those complexes dispatch several downstream signals, including those involved in the PI3K/AKT/mTOR pathway.

Conclusions: Drug discovery using halichondrins was based on their outstanding in vivo antitumor (inhibitory) activity in mice and bone metastasis in mouse melanoma model first reported in 1996. From these results, we hypothesized that halichondrins are not simple microtubule-targeted compounds in tumor cell, and have developed E7130, which harbors unique tumor microenvironment ameliorating effects. Here we proved that E7130 impedes the TGF-β-induced myofibroblast transdifferentiation process without killing the fibroblast by disrupting microtubule network formation, which is important for focal adhesion assembly and thereby the downstream activation of the PI3K/AKT/mTOR pathway.

Citation Format: Takanori Abe, Satoshi Kawano, Ken Ito, Kenzo Yahata, Kazunobu Kira, Tsuyoshi Akagi, Makoto Asano, Kentaro Iso, Yuki Sato, Fumiyoshi Matsuura, Isao Ohashi, Yasunobu Matsumoto, Minetaka Isomura, Takeo Sasaki, Takashi Fukuyama, Yusuke Miyashita, Yosuke Kaburagi, Akira Yokoi, Osamu Asano, Takashi Owa, Yoshito Kishi. Mechanism of action analysis of anti-CAF activity of E7130, a novel tumor-microenvironment ameliorator [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4183.

Abstract 4419: Subtyping of HNSCC single-cell RNA-seq identifies transcriptional programs characterized by suppression of Mtorc1 and Wnt signaling pathways and better patient prognosis

Single-cell RNA-seq (scRNA-seq) is an emerging platform for high-throughput profiling of individual cells in a sample and is routinely employed to investigate the transcriptional landscapes of the cellular constituents of tumors. To this end, many scRNA-seq specific clustering algorithms have emerged to analytically partition cells into modules of comparatively similar profiles. To facilitate data driven molecular subtyping of such scRNA-seq clustering results and other large-scale-omics studies, we have developed K2 Taxonomer. K2 Taxonomer is an R package built around a novel top-down hierarchical clustering algorithm, utilizing repeated perturbations of the data to generate robust taxonomical partitions of observations. The software runs additional analyses to define gene co-expression signatures of these modules, as well as to integrate user-input annotations of genes and/or observations. An interactive web portal has been generated to assist in the interrogation of the full compendium of results.

We applied K2 Taxonomer to publicly available HNSCC scRNA-seq data, identifying pertinent tumor cell subtypes, distinguished by cell cycle and epithelial-to-mesenchymal transition, and with analytical projection of this signature onto TCGA-HNSCC bulk RNA-seq data exhibiting association with worse survival in TCGA-HNSCC patients. A transcriptional signature corresponding to suppression of Mtorc1 and Wnt/β-catenin signaling was also identified in a sub-population of HNSCCs, and shown to be associated with improved patient survival. Of notice, highly ranked markers of this signature are significantly associated with gene expression changes altered by E7386 - a novel β-catenin/CBP modulator with an activity profile that closely overlaps with that of ICG-001, but exhibits ~50-100-fold lower EC50 values - suggesting a role for this signaling axis in subsets of HNSCC. In conclusion, taxonomical subtyping with K2 Taxonomer provides a novel framework to expand the scope of applicability of scRNA-seq clustering results, and has revealed potentially novel HNSCC subtypes that offer directions for future studies.

Citation Format: Eric Reed, Takashi Owa, Kenichi Nomoto, Xaralabos Varelas, Maria Kukuruzinska, Stefano Monti. Subtyping of HNSCC single-cell RNA-seq identifies transcriptional programs characterized by suppression of Mtorc1 and Wnt signaling pathways and better patient prognosis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4419.

Abstract 2453: Inhibition of β-catenin/CBP signaling with E7386 targets epigenetic changes associated with cancer stem cells in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is a pernicious malignancy that arises from populations of cancer stem cells (CSCs). We and others have shown that the Wnt/β-catenin signaling pathway drives CSC gene expression mediated, in part, by epigenetic alterations directed by interactions between nuclear β-catenin and the cAMP-responsive element binding (CREB)-binding protein (CBP). In HNSCC, the β-catenin/CBP complex recruits the histone methyltransferase, MLL1, to drive trimethylation of H3K4me3 to induce an open chromatin structure and expression of CSC genes. Further, β-catenin/CBP signaling is highly correlated with the activity of the paralogous transcriptional regulators YAP and TAZ (YAP/TAZ), which are pro-tumorigenic factors in HNSCC. We reported that a small molecule inhibitor of the β-catenin-CBP interaction, ICG-001, blocks oncogenic phenotypes in cellular, zebrafish, and murine models of HNSCC, concomitant with the reduction of CSC traits. Recently, a novel β-catenin/CBP modulator, E7386, has been shown to be effective against a number of neoplasms in preclinical studies. Here, we compared anti-cancer properties of E7386 with ICG-001 to define its molecular mechanisms and validate the β-catenin/CBP axis as a bona fide therapeutic target in HNSCC.

Anti-HNSCC activity of E7386 was evaluated in four human HNSCC cell lines using genomic, molecular, biochemical and functional approaches, including global ChIP-seq for H3K4me3. The set of transcripts significantly down-regulated by E7386 in HNSCC cells was projected onto a TCGA RNA-seq data (n=318) using ASSIGN, where samples were scored based on the coordinated expression of the gene signature which, in turn, reflected the level of E7386 inhibition per sample. The E7386 inhibition score was then tested for its association with survival by stratifying TCGA patients (n=318) into high- and low-score groups. Results showed that E7386 had highly overlapping activity signatures with ICG-001 (R = 0.997) with ~50 - 100-fold lower EC50. Similar to ICG-001, treatment with E7386 blocked association between β-catenin and CBP with a concomitant reduction in CBP and MLL1 abundance and global H3K4 trimethylation. E7386 repressed an oncogenic gene expression signature regulated by YAP1/TAZ and impeded HNSCC cell proliferation, promoting E-cadherin adhesion and junctional localization of β-catenin. Importantly, E7386 inhibition-associated transcriptional signatures tracked with tumor grade and poor human HNSCC patient survival. In conclusion, inhibiting β-catenin/CBP activity with E7386 represents a novel approach aimed at targeting epigenetically driven changes in the chromatin structure in HNSCC.

Citation Format: Huamei Yang, Vinay Kartha, Khalid A. Alamoud, Anthony Federico, Andrew Tilston-Lunel, Bach-Cuc Nguyen, Takashi Owa, Kenichi Nomoto, Xaralabos Varelas, Stefano Monti, Maria A. Kukuruzinska. Inhibition of β-catenin/CBP signaling with E7386 targets epigenetic changes associated with cancer stem cells in head and neck cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2453.

Enhancement of Soft Tissue Sarcoma Response to Gemcitabine through Timed Administration of a Short-Acting Anti-Angiogenic Agent

BACKGROUND/AIMS

Despite enormous effort, anti-angiogenic drugs have not lived up to the promise of globally-enhancing anti-cancer therapies. Clinically, anti-angiogenic drugs have been used to persistently suppress vascular endothelial growth factor (VEGF) in order to "normalize" dysfunctional neo-angiogenic microvasculature and prevent recruitment of endothelial progenitors. Recently, we showed that a 1h pre-treatment with anti-angiogenic drugs prior to ultra-high single dose radiotherapy and specific chemotherapies transiently de-represses acid sphingomyelinase (ASMase), leading to enhanced cancer therapy-induced, ceramide-mediated vascular injury and tumor response. Here we formally decipher parameters of chemotherapy induction of endothelial sphingolipid signaling events and define principles for optimizing anti-angiogenic chemosensitization.

METHODS

These studies examine the antimetabolite chemotherapeutic gemcitabine in soft tissue sarcoma (STS), a clinically-relevant combination.

RESULTS

Initial studies address the theoretic problem that anti-angiogenic drugs such as bevacizumab, an IgG with a 3-week half-life, have the potential for accumulating during the 3-week chemotherapeutic cycles currently standard-of-care for STS treatment. We show that anti-angiogenic ASMase-dependent enhancement of the response of MCA/129 fibrosarcomas in sv129/BL6 mice to gemcitabine progressively diminishes as the level of the VEGFR2 inhibitor DC101, an IgG, accumulates, suggesting a short-acting anti-angiogenic drug might be preferable in multi-cycle chemotherapeutic regimens. Further, we show lenvatinib, a VEGFR2 tyrosine kinase inhibitor with a short half-life, to be superior to DC101, enhancing gemcitabine-induced endothelial cell apoptosis and tumor response in a multi-cycle treatment schedule.

CONCLUSION

We posit that a single delivery of a short-acting anti-angiogenic agent at 1h preceding each dose of gemcitabine and other chemotherapies may be more efficacious for repeated sensitization of the ASMase pathway in multi-cycle chemotherapy regimens than current treatment strategies.

β-Catenin/CBP inhibition alters epidermal growth factor receptor fucosylation status in oral squamous cell carcinoma

Epidermal growth factor receptor (EGFR) is a major driver of head and neck cancer, a devastating malignancy with a major sub-site in the oral cavity manifesting as oral squamous cell carcinoma (OSCC). EGFR is a glycoprotein receptor tyrosine kinase (RTK) whose activity is upregulated in >80% OSCC. Current anti-EGFR therapy relies on the use of cetuximab, a monoclonal antibody against EGFR, although it has had only a limited response in patients. Here, we uncover a novel mechanism regulating EGFR activity, identifying a role of the nuclear branch of the Wnt/β-catenin signaling pathway, the β-catenin/CBP axis, in control of post-translational modification of N-glycans on the EGFR. Genomic and structural analyses reveal that β-catenin/CBP signaling represses fucosylation on the antennae of N-linked glycans on EGFR. By employing nUPLC-MS/MS, we determined that malignant human OSCC cells harbor EGFR with a paucity of N-glycan antennary fucosylation, while indolent cells display higher levels of fucosylation at sites N420 and N579. Additionally, treatment with either ICG-001 or E7386, which are both small molecule inhibitors of β-catenin/CBP signaling, leads to increased transcriptional expression of fucosyltransferases FUT2 and FUT3, with a concomitant increase in EGFR N-glycan antennary fucosylation. In order to discover which fucosylated glycan epitopes are involved in the observed effect, we performed in-depth characterization of multiply-fucosylated N-glycans via tandem mass spectrometry analysis of the EGFR tryptic glycopeptides. Data are available via ProteomeXchange with identifier PXD017060. We propose that β-catenin/CBP signaling promotes EGFR oncogenic activity in OSCC by inhibiting its N-glycan antennary fucosylation through transcriptional repression of FUT2 and FUT3.

Abstract 275: A possible relationship between gene mutation profiles and activity of E7386 in in vitro models of colorectal cancer organoids

A novel beta-catenin/CBP binding modulator E7386 is expected to affect colorectal carcinoma (CRC) cells particularly those with aberrant activation of Wnt/beta-catenin signaling pathway. The Wnt signaling pathway is recently reported to play important roles for activation of not only CRC cells but also cancer-associated fibroblasts (CAFs). Here, we established an in vitro model of CRC-derived organoids as well as a co-culture method of the CRC organoids with CAFs, and effects of E7386 on the growth of the organoids were examined. Fragments of CRC tissues from a total of 45 patients who underwent surgery were obtained, dissociated into single cells, which were seeded on polymerized Matrigel (Corning), and cultured with serum-free media containing EGF and Noggin optimized for organoids using 12-well plates. Fourteen CRC organoids from 45 cases were successfully established. For 2D culture of CAFs from CRC tissues of each patient, RPMI medium containing 10% FBS was used. A co-culture method of the CRC organoids with CAFs was applied using a double chamber system with transwell inserts in 24-well plates. Cell viabilities of the organoids and CAFs were measured using CellTiter-Glo Luminescent Cell Viability Assay reagent (Promega). Gene aberrations in original CRC tissues were analyzed using NCC Oncopanel, and gene expression profiles in established CRC organoids and CAFs were analyzed using SurePrint G3 Human GE microarray (Agilent). [Effects of CAFs on cell viabilities and gene expressions of organoids] Cell viabilities of organoids and CAFs appeared to increase at 72 hours after beginning of the culture by 2 to 8 and 1 to 2-fold, respectively. When organoids were co-cultured with CAFs, cell viabilities of organoids were increased and epithelial-mesenchymal transition-related gene expressions were dramatically changed in several cases, but not in all cases. The organoids co-cultured with CAFs appeared to be more sensitive to E7386 as compared to those cultured alone. [Possible relationship between gene mutations in CRCs and activity of E7386 in CRC organoids] Cell viabilities of organoids without APC mutations (n=1) and organoids with APC and TP53 mutations alone (n=2) were less than those of organoids with other oncogene mutations, e.g., KRAS or PIK3CA (n=4). Efficacy of E7386 on the cell viabilities of organoids with APC and TP53 mutations alone was found at lower concentrations at 30-100 nM, as compared to those of organoids without APC mutations. From the results, CRC organoids were established from 14 patients, and activity of E7386 appeared to be related to gene mutation profiles in the established CRC organoids.

Citation Format: Toshio Imai, Mie Naruse, Masako Ochiai, Yoichi Ozawa, Takashi Owa, Atsushi Ochiai. A possible relationship between gene mutation profiles and activity of E7386 in in vitro models of colorectal cancer organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 275.

Targeting an RNA-Binding Protein Network in Acute Myeloid Leukemia

RNA-binding proteins (RBPs) are essential modulators of transcription and translation frequently dysregulated in cancer. We systematically interrogated RBP dependencies in human cancers using a comprehensive CRISPR/Cas9 domain-focused screen targeting RNA-binding domains of 490 classical RBPs. This uncovered a network of physically interacting RBPs upregulated in acute myeloid leukemia (AML) and crucial for maintaining RNA splicing and AML survival. Genetic or pharmacologic targeting of one key member of this network, RBM39, repressed cassette exon inclusion and promoted intron retention within mRNAs encoding HOXA9 targets as well as in other RBPs preferentially required in AML. The effects of RBM39 loss on splicing further resulted in preferential lethality of spliceosomal mutant AML, providing a strategy for treatment of AML bearing RBP splicing mutations.

Final results of a phase 2, open-label study of indisulam, idarubicin, and cytarabine in patients with relapsed or refractory acute myeloid leukemia and high-risk myelodysplastic syndrome

BACKGROUND

Indisulam possesses anticancer properties through down-regulation of various cell-cycle checkpoint molecules, thereby blocking the phosphorylation of retinoblastoma protein and inducing p53 and p21. Indisulam exhibits synergy with nucleoside analogs and topoisomerase inhibitors.

METHODS

The authors designed a phase 2 study of indisulam in combination with idarubicin and cytarabine in patients who had relapsed/refractory acute myeloid leukemia AML and high-risk myelodysplastic syndrome. In stage 1, patients received intravenous indisulam at 400 mg/m² on days 1 and 8 of a 28-day cycle. If they had no response, then patients received same dose schedule of indisulam followed by intravenous idarubicin 8 mg/m² daily for 3 days and cytarabine 1.0 g/m² over 24 hours daily on days 9 through 12 (for those aged < 60 years) or days 9 through 11 (for those aged > 60 years) of a 28-day cycle. Primary endpoints included the overall response rate, and secondary objectives included overall survival.

RESULTS

Forty patients were enrolled. Of the 37 evaluable patients, 31 received indisulam with chemotherapy. Of these, 11 (35%) responded for a median duration of 5.3 months. The estimated 1-year overall survival rate was 51% for responders compared with 8 % for nonresponders (P < .001). The most common grade ≥3 nonhematologic toxicities were electrolyte abnormalities (50%) and febrile neutropenia (28%).

CONCLUSIONS

The combination of indisulam with idarubicin and cytarabine yielded a 35% response rate in heavily pretreated patients with AML. With emerging data identifying the expression of DCAF15 (DDB1 and CUL4-associated factor 15) as a potential biomarker for activity, the combination of indisulam with idarubicin and cytarabine should be studied in a biomarker-driven trial or in patients who have splicing factor mutations. Cancer 2018;124:2758-65. © 2018 American Cancer Society. Cancer 2018;124:2758-2765. © 2018 American Cancer Society.

Phase I study of E7046, a novel PGE2 receptor type 4 inhibitor, in patients with advanced solid tumors: Clinical results and effects on myeloid- and T-lymphoid cell-mediated immunosuppression

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Background: E7046 is a selective inhibitor of the prostaglandin E2 (PGE2) receptor EP4, which transduces potent immunosuppressive activity of PGE2 in myeloid and T-lymphoid cells. In preclinical studies, E7046 reversed PGE2-mediated activities and facilitated activation of cytotoxic T-cells. Here, we present initial clinical, PK and PD results from a first-in-human study of E7046 in patients (pts) with cancers having high myeloid cell infiltration. Methods: E7046 was given orally, once-daily, in 21-day cycles in sequential dose-escalating cohorts (125, 250, 500 and 750mg). Tumor responses were evaluated by irRECIST and metabolic responses by 18FDG-PET. Immune response modulation was assessed in tumors and peripheral blood. Results: Thirty pts were treated, with no dose-limiting toxicities observed. The most common adverse events were fatigue (37%), diarrhea (33%), and nausea (30%). Grade 3/4 AEs in > 1 pt were abdominal pain (3 pts) and vomiting (2 pts). Grade 3/4 treatment-related AEs occurred in 4 pts (rash in 2 pts, and diarrhea, allergic reaction, anaphylaxis, hypersensitivity, and hyperuricemia, in 1 pt each). Four pts discontinued E7046 due to an AE (bowel obstruction, allergic reaction, abdominal pain, acute renal failure). No objective tumor responses were reported. Treatment duration of ≥20 wks with best response of stable disease (SD) was observed in 5 pts, 3 of whom had partial metabolic responses. E7046 exposure was dose-proportional up to 500 mg. Elimination half-life (12 hr) justified once-daily dosing. E7046 treatment significantly increased tumor CD3+ and CD8+ T-cell infiltration, and blood levels of the T-cell-recruiting chemokine CXCL10. E7046 also modulated blood expression of EP4 signaling genes (IDO1, EOMES, PD-L1). Longer duration of therapy with SD was associated with higher baseline tumor infiltrate of CD8+ T-cells and CD163+ macrophages. Conclusions: E7046 demonstrated favorable tolerability with preliminary evidence of anti-tumor activity and immune modulation in tumor and peripheral blood. MTD was not reached. Further studies of E7046 in combination with other agents are planned. Clinical trial information: NCT02540291.

Abstract 5177: E7386 : First-in-class orally active CBP/beta-catenin modulator as an anticancer agent

Carcinogenesis is often accelerated by the aberrant activation of components molecules of Wnt signaling pathway, especially, APC and beta-catenin are frequently reported to be mutated in various cancers. Therefore, Wnt signal pathway is thought to be one of the attractive therapeutic targets. PRI-724 generated by PRISM Pharma is a small molecule inhibitor of beta-catenin and its transcriptional coactivator CREB binding protein (CBP) thereby specific modulating Wnt/beta-catenin signaling pathway by intravenous continuous infusion. Here we firstly generated orally active small molecular inhibitor, E7386. E7386 disrupted the interaction between beta-catenin and CBP in co-immunoprecipitation assay. E7386 inhibited canonical Wnt signaling pathway /TCF reporter gene activity in LiCl-stimulated HEK-293 and MDA-MB-231 in a dose dependent manner with IC50 values of 55 nmol/L and 73 nmol/L, respectively. E7386 modulated the expression of Wnt signaling pathway related genes including AXIN2 and other genes, which were down-regulated by artificial knockdown of beta-catenin. These results indicate that E7386 controls the expression of Wnt target genes through modulation of beta-catenin/CBP interaction. Next we investigated anti-polyposis effect in ApcMin/+ mice as an in vivo proof of mechanism model. ApcMin/+ mice develops polyps in the intestinal tract caused by the aberrant activation of Wnt/beta-catenin signaling pathway. Oral administration of E7386 significantly suppressed the number of polyposis in a dose dependent manner at the dose range from 8.5 to 50 mg/kg. In addition, E7386 significantly changed the expressions of Wnt related genes in whisker follicle of ApcMin/+mice model. Finally, we investigated anti-tumor activity of E7386 in vitro tumor proliferation panel against 28 human tumor cell lines. E7386 showed relatively potent anti-proliferative activity against cancer cell lines harboring exclusively mutated Wnt signaling pathway molecules such as APC or beta-catenin. E7386 also showed significant antitumor activity in a dose dependent manner on human tumor cell line xenograft harboring APC mutation. Taken together, E7386 is a first in class orally active CBP/beta-catenin modulator and showed potent inhibitory activity against aberrant activation of Wnt/beta-catenin signaling pathway.

Citation Format: Kazuhiko Yamada, Yusaku Hori, Atsumi Yamaguchi, Masahiro Matsuki, Shuntaro Tsukamoto, Akira Yokoi, Taro Semba, Yoichi Ozawa, Satoshi Inoue, Yuji Yamamoto, Kentaro Iso, Kazutaka Nakamoto, Hitoshi Harada, Naoki Yoneda, Atsushi Takemura, Masayuki Matsukura,, Kenji Kubara, Takenao Odagami, Masao Iwata, Akihiko Tsuruoka, Toshimitsu Uenaka, Junji Matsui, Tomohiro Matsushima, Kenich Nomoto, Hiroyuki Kouji, Takashi Owa. E7386 : First-in-class orally active CBP/beta-catenin modulator as an anticancer agent [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5177. doi:10.1158/1538-7445.AM2017-5177

Abstract 5172: E7386, an orally active CBP/beta-catenin modulator, induces T cells infiltration into tumor and enhances antitumor activity of anti-PD-1 mAb in Wnt1 tumor syngeneic mice model

Recently, immunotherapeutic approaches have come to forefront in melanoma, non-small cell lung cancer, bladder cancer, and so on. However, sufficient benefits from these treatments have been limited. T cell infiltrating into tumor tissues is reported as one of the response biomarker candidates for the immune checkpoint inhibitors. Recent studies have shown that the activation of the Wnt/beta-catenin signaling pathway results in T cell exclusion and resistance to immune checkpoint inhibitor in melanoma patients. We established the Wnt1 tumor syngeneic mice model (Wnt1 model) by implantation of mammary adenocarcinomas isolated from MMTV-Wnt1 transgenic mice. Here we demonstrate whether E7386, a first-in-class orally active CBP/beta-catenin modulator, affects the recruitment of T cells into tumor tissues, leading to the enhancement of anti-PD-1 mAb in Wnt/beta-catenin signaling pathway activating tumor model. The mice were treated with E7386 (50 mg/kg, orally, BID) and/or anti-mouse PD-1 mAb (10 mg/kg, intraperitoneal, twice a week) for three weeks. Tumor diameters are measured with digital calipers, and the tumor volume in mm3 is calculated. Immunohistochemical (IHC) analysis was evaluated for tumor-infiltrating T cells. E7386 showed significant antitumor activity in Wnt1 model, but anti-PD-1 mAb did not. In contrast, E7386 with anti-PD-1 mAb indicated prominent antitumor activity compared to each single treatment. Enhancement of body weight loss in combination group was not observed. In IHC analysis, infiltration of T cells was limited in vehicle control group, in contrast T cell infiltration into tumors was clearly observed in both E7386 treatment group and combination group. As a result, antitumor activity of immune checkpoint inhibitor was limited in Wnt-driven tumor model and E7386 as a novel CBP/beta-catenin modulator enhanced the antitumor activity of anti-PD-1 mAb via induction of tumor-infiltrating T cells.

Citation Format: Yusaku Hori, Kazuhiko Yamada, Yu Kato, Yoichi Ozawa, Takenao Odagami, Junji Matsui, Tomohiro Matsushima, Kenichi Nomoto, Hiroyuki Kouji, Takashi Owa. E7386, an orally active CBP/beta-catenin modulator, induces T cells infiltration into tumor and enhances antitumor activity of anti-PD-1 mAb in Wnt1 tumor syngeneic mice model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5172. doi:10.1158/1538-7445.AM2017-5172

Abstract 580: Chemical transcriptomic analysis illuminates a class of anticancer sulfonamide derivatives undergoing clinical investigation

Microarray-based gene expression analysis allows us to understand a comprehensive transcriptional profile as one of the fine cellular phenotypes after anticancer drug treatment. Analytical programs with bioinformatics are also useful to connect a gene expression fingerprint pattern with relevant cellular pathways to drug treatment. We have so far tested more than 40 anticancer small molecules, including standard drugs and investigational ones, with respect to their transcriptional profiles using a unified microarray assay condition. Interestingly, our pilot study to evaluate14 different anticancer agents simultaneously using Affymetrix GeneChip arrays illuminated that 6 sulfonamide derivatives had highly correlated transcriptional profiles with cosine coefficients being more than 0.70 in all pairwise combinations. By contrast, cosine coefficients were less than 0.30 in all combinations between one from the 6 sulfonamide derivatives and the other from the remaining 8 test compounds. These sulfonamide derivatives consist of chloroquinoxaline sulfonamide (CQS), LY186641 (sulofenur), LY295501, LY573636 (tasisulam), E7070 (indisulam) and E7820, all of which have been actively investigated in clinical trials. Among them, LY573636 is a most advanced agent, currently undergoing a phase III study in comparison with paclitaxel as second line treatment in patients with melanoma. E7820 is also being evaluated in a phase II study in combination with cetuximab in patients with refractory metastatic colorectal cancer. To examine whether these 6 sulfonamide derivatives truly share the same cellular target and mechanism of action (MOA), we further carried out 40 cancer cell line COMPARE analysis and cell-based cross-resistance assays. In the former experiment, these 6 sulfonamide derivatives demonstrated very similar antiproliferative meangraph profiles with Pearson's correlation coefficients being more than 0.82 in all pairwise combinations. The latter experiment revealed that two E7070-resistant sub-clonal colorectal cancer cell lines HCT116-C9C1 and -C9C4 were cross-resistant to the other 5 sulfonamide derivatives than E7070. Importantly, the drug resistance mechanism was considered irrelevant to P-gp overexpression. Despite long and intensive exploratory researches, the precise cellular target and MOA of this class of anticancer agents have yet to be fully elucidated. A piece of information has been reported on the production of reactive oxygen species and mitochondria-mediated cellular apoptosis with LY573636 and E7820, independently. Our chemical transcriptomic profiling and pathway analysis herein define a novel class of anticancer sulfonamide derivatives. The present data may provide some insight into their unique MOA based on the distinctive and profound down-regulation of sets of critical cellular metabolism genes.

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 580. doi:10.1158/1538-7445.AM2011-580

Microarray-based transcriptional profiling of renieramycin M and jorunnamycin C, isolated from Thai marine organisms

Renieramycin M and jorunnamycin C, two isoquinolinequinone compounds differing only at the C-22 ester side chain, were evaluated for their cytotoxic effects on human colon (HCT116) and breast (MDA-MB-435) cancer cell lines. These two compounds displayed potent cancer cell growth inhibition, their IC(50) values reaching nanomolar order. To examine their effects on transcription, we carried out oligonucleotide microarray analysis with focus on the similarities and differences between the two compounds in terms of transcriptional profiles. We found that the down-regulation of PTPRK (protein tyrosine phosphatase receptor type K) can be considered as a biomarker responsive to the cytotoxic effects of this class of antitumor marine natural products.

Chemistry of renieramycins. Part 8: synthesis and cytotoxicity evaluation of renieramycin M-jorunnamycin A analogues

Twenty-four ester analogues of renieramycin M (1m) were prepared from jorunnamycin A (3a), which was easily transformed from marine natural 1m in three steps. These analogues, along with 1m itself, cyanojorumycin (2b), and jorunnamycins A (3a) and C (3b), were evaluated in vitro for cytotoxicity by measuring IC(50) values through the 3-(4,5-dimethyltriazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay using human HCT116 colon carcinoma and MDA-MB-435 breast carcinoma cell lines. Nitrogen-containing heterocyclic ester derivatives 9a-f showed similar in vitro cytotoxicity to 1m, whereas the other derivatives were slightly less cytotoxic than 1m. 2'-Pyridinecarboxylic acid ester derivative (9c) exhibited a threefold increase in cytotoxicity relative to 1m.

Clinical complete long-term remission of a patient with metastatic malignant melanoma under therapy with indisulam (E7070)

The objective of this study is to report on long-term survival of a patient with metastatic melanoma treated with indisulam showing a distinct genetic pattern of repression of subsets of genes involved in mitochondrial energy metabolism. Gene expression profiling was performed with oligonucleotide microarray analysis. A 45-year-old patient with metastatic malignant melanoma was treated in third-line with indisulam (goal, E7070), a new chloroindolyl-sulphonamide cell-cycle inhibitor. The patient was treated weekly with a dose of 40 mg/m within a phase I study. On the basis of an amendment, the dose was escalated to 320 mg/m at maximum and de-escalated to 160 mg/m for long-term application in this individual patient. At the start of treatment the tumour burden consisted of two-in-transit-metastases, two further skin lesions, two cervical lymph nodes and four pulmonary metastases. Under a 2.5-year treatment with indisulam the tumour shrunk markedly although the objective response only reached stable disease. Lymph node biopsy revealed absence of vital melanoma cells. Therapy was stopped upon request of the patient. The gene expression profile indicated a profound transcriptional repression of subsets of genes involved in mitochondrial energy metabolism; namely NDUFB8, NDUFS1, NDUFV1, ACADVL and Homo sapiens clone 24408. The survival of this patient with metastatic melanoma lasted now 9 years, the progression-free interval 105 months. It can be assumed that this treatment effect is attributed to the down-regulating effect of indisulam on metabolic genes involved in energy production. Thus, knowledge on individual's tumour gene regulation may predict sensitivity and resistance to antitumoural agents.

Splicing factor SF3b as a target of the antitumor natural product pladienolide

Pladienolide is a naturally occurring antitumor macrolide that was discovered by using a cell-based reporter gene expression assay controlled by the human vascular endothelial growth factor promoter. Despite the unique mechanisms of action and prominent antitumor activities of pladienolides B and D in diverse in vitro and in vivo systems, their target protein has remained unclear. We used 3H-labeled, fluorescence-tagged and photoaffinity/biotin (PB)-tagged 'chemical probes' to identify a 140-kDa protein in splicing factor SF3b as the binding target of pladienolide. Immunoblotting of an enhanced green fluorescent protein fusion protein of SF3b subunit 3 (SAP130) revealed direct interaction between the PB probe and SAP130. The binding affinities of pladienolide derivatives to the SF3b complex were highly correlated with their inhibitory activities against reporter gene expression and cell proliferation. Furthermore, pladienolide B impaired in vivo splicing in a dose-dependent manner. Our results demonstrate that the SF3b complex is a pharmacologically relevant protein target of pladienolide and suggest that this splicing factor is a potential antitumor drug target.

Antimitotic Sulfonamides Inhibit Microtubule Assembly Dynamics and Cancer Cell Proliferation

Several sulfonamides have antitumor activities and are currently undergoing clinical evaluation for the treatment of cancer. In this study, we have elucidated the antiproliferative mechanism of action of five indole sulfonamides. The indole sulfonamides inhibited the polymerization of microtubule protein into microtubules in vitro. In addition, three representative derivatives, ER-68378 (2), ER-68384 (4) and ER-68394 (5), suppressed the dynamic instability behavior at the plus ends of individual steady-state microtubules in vitro. The analogues inhibited HeLa cell proliferation with half-maximal inhibitory concentrations in the range of 6-17 microM. The compounds blocked cell cycle progression at mitosis. At their lowest effective antimitotic concentrations, they depolymerized the spindle microtubules and disorganized the chromosomes but did not affect the microtubules in interphase cells. However, at relatively high concentrations, interphase microtubules were also depolymerized by these sulfonamides. Furthermore, all five compounds were found to induce apoptosis in the cells in association with the phosphorylation of bcl-2. The results suggest that the indole sulfonamides inhibit cell proliferation at mitosis by perturbing the assembly dynamics of spindle microtubules and that they can kill cancer cells by inducing apoptosis through the bcl-2-dependent pathway.

Sulfonamide drugs binding to the colchicine site of tubulin: thermodynamic analysis of the drug-tubulin interactions by isothermal titration calorimetry

The discovery of several sulfonamide drugs paved the way toward the synthesis of 6 (N-[2-[(4-hydroxyphenyl)amino]-3-pyridinyl]-4-methoxybenzenesulfonamide, E7010) and 7 (N-(3-fluoro-4-methoxyphenyl)pentafluorobenzenesulfonamide, T138067), both of which inhibit tubulin polymerization and are under clinical development. A series of diarylsulfonamides containing an indole scaffold was also found to have antimitotic properties, but their mode of interactions with tubulin has remained unidentified so far. In this study, we demonstrate that these sulfonamide drugs bind to the colchicine site of tubulin in a reversible manner. They quenched intrinsic tryptophan fluorescence of tubulin presumably due to drug-induced conformational changes in the protein, but were unable to modulate GTPase activity of tubulin in contrast to colchicine that enhances the same enzymatic activity. Further investigation using isothermal titration calorimetry (ITC) revealed that 5 (N-(5-chloro-7-indolyl)-4-methoxybenzenesulfonamide) afforded a large positive value of heat capacity change (DeltaC(p)() = +264 cal mol(-1) K(-1)) on binding to tubulin, suggesting a substantial conformational transition in the protein along with partial enthalpy-entropy compensation. On the other hand, the 2-chloro regioisomer 2 gave a large negative value of DeltaC(p)() (-589 cal mol(-1) K(-1)) along with complete enthalpy-entropy compensation. This thermodynamic profile was thought to be attributable to a prominent contribution of van der Waals interaction and hydrogen bonding between specific groups in the drug-tubulin complex. These results indicate that a mere alteration in the position of a single substituent chlorine on the indole scaffold has a great influence on the drug-tubulin binding thermodynamics.

Carbonic anhydrase inhibitors: E7070, a sulfonamide anticancer agent, potently inhibits cytosolic isozymes I and II, and transmembrane, tumor-associated isozyme IX

E7070 [N-(3-chloro-7-indolyl)-1,4-benzenedisulfonamide] is an anticancer drug candidate under clinical development for the treatment of several types of cancers. We prove here that this compound also acts as a potent carbonic anhydrase (CA) inhibitor. Similarly to the clinically used drugs acetazolamide, methazolamide and topiramate, E7070 showed inhibition constants in the range of 15-31nM against isozymes I, II and IX, being slightly less effective as a CA IV inhibitor (K(i) of 65nM). The X-ray crystal structure of the adduct of hCA II with E7070 revealed unprecedented interactions between the inhibitor and the active site, with three different conformations of the chloroindole fragment of the inhibitor interacting with different amino acid residues/water molecules of the enzyme. A superimposition of these conformations with those of other sulfonamide/sulfamate CA inhibitors indicated that similar regions of the hCA II active site could be involved in the interaction with inhibitors.

Anticancer and antiviral sulfonamides

The sulfonamides constitute an important class of drugs, with several types of pharmacological agents possessing antibacterial, anti- carbonic anhydrase, diuretic, hypoglycemic and antithyroid activity among others. A large number of structurally novel sulfonamide derivatives have ultimately been reported to show substantial antitumor activity in vitro and in vivo. Although they have a common chemical motif of aromatic/heterocyclic or amino acid sulfonamide, there are a variety of mechanisms of their antitumor action, such as carbonic anhydrase inhibition, cell cycle perturbation in the G1 phase, disruption of microtubule assembly, functional suppression of the transcriptional activator NF-Y, and angiogenesis (matrix metalloproteinase, MMP) inhibition among others. Some of these compounds selected via elaborate preclinical screenings or obtained through computer-based drug design, are currently being evaluated in clinical trials. The review summarizes recent classes of sulfonamides and related sulfonyl derivatives disclosed as effective tumor cell growth inhibitors, or for the treatment of different types of cancer. Another research line that progressed much in the last time regards different sulfonamides with remarkable antiviral activity. Thus, at least two clinically used HIV protease inhibitors possess sulfonamide moieties in their molecules, whereas a very large number of other derivatives are constantly being synthesized and evaluated in order to obtain compounds with less toxicity or activity against drug-resistant viruses. Several non nucleoside HIV reverse transcriptase or HIV integrase inhibitors containing sulfonamido groups were also reported. Another approach to inhibit the growth of retroviruses, including HIV, targets the ejection of zinc ions from critical zinc finger viral proteins, which has as a consequence the inhibition of viral replication in the absence of mutations leading to drug resistance phenotypes. Most compounds with antiviral activity possessing this mechanism of action incorporate in their molecules primary sulfonamide groups. Some small molecule chemokine antagonists acting as HIV entry inhibitors also possess sulfonamide functionalities in their scaffold.

Quantitative chemical proteomics for identifying candidate drug targets

We have developed a systematic strategy for drug target identification. This consists of the following sequential steps: (1) enrichment of total binding proteins using two differential affinity matrixes upon which are immobilized positive and negative chemical structures for drug activity, respectively; (2) covalent labeling of the proteins with a new cleavable isotope-coded affinity tag (ICAT) reagent, followed by proteolysis of the combined proteins; (3) isolation, identification, and relative quantification of the tagged peptides by liquid chromatography-mass spectrometry; (4) array-based transcription profiling to select candidate proteins; and (5) confirmation of direct interaction between the activity-associated structure and the selected proteins by using surface plasmon resonance. We present a typical application to identify the primary binding protein of a novel class of anticancer agents exemplified by E7070. Our results suggest that this approach provides a new aspect of quantitative proteomics to find specific binding proteins from protein mixture and should be applicable to a wide variety of biologically active small molecules with unidentified target proteins.

Sulfonamide derivative, E7820, is a unique angiogenesis inhibitor suppressing an expression of integrin alpha2 subunit on endothelium

In the process of angiogenesis, endothelial adhesion molecules play a significant role in vascular morphogenesis, in coordination with angiogenic factor signaling. Here we report that a novel angiogenesis inhibitor, E7820 (an aromatic sulfonamide derivative), inhibited in vitro proliferation and tube formation of human umbilical vascular endothelial cell (HUVEC). E7820 decreased integrin alpha2, 3, 5, and beta1 in confluent culture of HUVEC, and integrin alpha2 was initially suppressed in mRNA level, followed by decrement of integrins alpha3, 5, and beta1. The inhibition of integrin alpha2 expression in HUVEC showed dose dependence but did not alter the level of CD31. Up-regulation of integrin alpha2 by phorbol 12-myristate 13-acetate abrogated the inhibitory effect of E7820 on tube formation within type I collagen gel, whereas addition of antibody against integrin alpha2 canceled the phorbol 12-myristate 13-acetate effect. These results suggest that E7820 inhibited tube formation through the suppression of integrin alpha2. Oral administration of E7820 remarkably resulted in inhibition of tumor-induced angiogenesis in mouse dorsal air sac model, and tumor growth of human colorectal tumor cell lines (WiDr and LoVo) was inhibited in xenotransplanted model in mice. This is the first time that a small molecule has been shown to modulate integrins, and this finding may provide the basis for a new approach to antiangiogenic therapy through the suppression of integrin alpha2 on endothelium.

Array-based structure and gene expression relationship study of antitumor sulfonamides including N-[2-[(4-hydroxyphenyl)amino]-3-pyridinyl]-4-methoxybenzenesulfonamide and N-(3-chloro-7-indolyl)-1,4-benzenedisulfonamide

Compounds from sulfonamide-focused libraries have been evaluated in cell-based antitumor screens using the COMPARE analysis with a panel of 39 human cancer cell lines and flow cytometric cell cycle analysis. Thus far, 2 (N-[2-[(4-hydroxyphenyl)amino]-3-pyridinyl]-4-methoxybenzenesulfonamide (E7010)) and 3 (N-(3-chloro-7-indolyl)-1,4-benzenedisulfonamide (E7070)) have been selected from the collections as potent cell cycle inhibitors, which have progressed to clinical trials. Compound 2 is an orally active antimitotic agent disrupting tubulin polymerization, whereas compound 3 belongs to a novel class of antiproliferative agents causing a decrease in the S phase fraction along with G1 and/or G2 accumulation in various cancer cell lines. Because both compounds exhibited preliminary clinical activities in the phase I setting, we decided to examine further this series of oncolytic small molecules, particularly by using high-density oligonucleotide microarray analysis. The array data have enabled us to characterize these two classes of antitumor sulfonamides on the basis of gene expression changes, illuminating the essential pharmacophore structure and drug-sensitive cellular pathways for each class. Moreover, the dual character of 5 (N-(3-chloro-7-indolyl)-4-methoxybenzenesulfonamide (ER-67880)), resembling both 2 and 3, was revealed by array-based transcription profiling, though the 3-type profile of this molecule had not been apparent in the cell-based phenotypic screens. These results provide an example of the utility of structure and gene expression relationship studies in medicinal genomics.

Synthesis and biological evaluation of N-(7-indolyl)-3-pyridinesulfonamide derivatives as potent antitumor agents

We herein report the synthesis and antitumor activity of E7070 analogues containing a 3-pyridinesulfonamide moiety. E7070 was selected from our sulfonamide-based compound collections, currently undergoing Phase II clinical trials because of its tolerable toxicity profile and some antitumor responses in the Phase I setting. Of the analogues examined, ER-35745, a 6-amino-3-pyridinesulfonamide derivative, demonstrated significant oral efficacy against the HCT116 human colon carcinoma xenograft in nude mice.

Profiling novel sulfonamide antitumor agents with cell-based phenotypic screens and array-based gene expression analysis

A series of small molecules from sulfonamide-focused libraries have been evaluated in these laboratories to discover novel antitumor agents. Cell-based screens using flow cytometric analysis revealed the presence of two distinct classes of cell cycle inhibitors in this series; one (including E7010 and ER-67865) arrested mitosis by preventing tubulin polymerization; and the other (including E7070 and ER-68487) caused a decrease in the S-phase fraction along with cell cycle perturbation in G1 and/or G2 via an unknown mechanism(s). To further characterize both classes of antitumor sulfonamides with respect to their effects on gene expression, we used oligonucleotide microarray analysis for representative compounds. Consistent with the phenotypic observations, essentially the same transcription profiles were found between E7010 and ER-67865 and also between E7070 and ER-68487. However, there was very little overlap between genes affected by E7010 and E7070. As a characteristic expression change for microtubule-depolymerizing agents, the down-regulation of alpha-tubulin transcripts was evident in both E7010- and ER-67865-treated cells. On the other hand, E7070 and ER-68487 repressed significantly the expression of a variety of genes involved in metabolic processes, cell cycle progression, immune response, and signal transduction. Of the compounds examined, E7010 and E7070 have progressed to clinical trials, demonstrating some objective responses in the Phase I setting. Described herein is profiling of novel anticancer drug candidates from the sulfonamide class based on phenotypic screens and gene expression analysis. This includes a translational research that may suggest potentially useful markers for pharmacodynamic drug assessment in clinic.

Antitumor activity- and gene expression-based profiling of ecteinascidin Et 743 and phthalascidin Pt 650

BACKGROUND

Ecteinascidin 743 (Et 743) is a potent antitumor marine alkaloid currently undergoing phase II clinical trials. The synthetic analog phthalascidin (Pt 650), a designed structural analog of Et 743 displays in vitro potency comparable to Et 743. In this study, we used a panel of 36 human cancer cell lines, flow cytometry and oligonucleotide microarrays to analyze further these two compounds in a parallel fashion with regard to both antitumor activity (phenotype) and gene expression (genotype) bases.

RESULTS

The cancer panel experiment established that activity patterns of Et 743 and Pt 650 were essentially the same with their IC(50) values ranging from pM to low nM. By means of flow cytometric cell cycle analysis using HCT116 cells, they were shown to disrupt S phase progression after a 12-h treatment at 2.0 nM, eventually resulting in the late S and G2/M accumulation at the 24-h time point. Array-based gene expression monitoring also demonstrated that the Et 743 and Pt 650 profiles were highly similar in two distinct cancer cell lines, HCT116 colon and MDA-MB-435 breast. Characteristic changes were observed in subsets of genes involved in DNA damage response, transcription and signal transduction. In HCT116 carrying the wild-type p53 tumor suppressor gene, the up-regulation of several p53-responsive genes was evident. Furthermore, a subset of genes encoding DNA-binding proteins to specific promoter regions (e.g. the CCAAT box) was down-regulated in both cell lines, suggesting one potential mode of action of this series of antitumor agents.

CONCLUSION

A combination of gene expression analysis using oligonucleotide microarrays and flow cytometry confirms an earlier finding that Et 743 and Pt 650 have remarkably similar biological activities.

E7070, a novel sulphonamide agent with potent antitumour activity in vitro and in vivo

E7070 (N-(3-Chloro-7-indolyl)-1,4-benzenedisulphonamide) was selected from our sulphonamide compound collections via antitumour screening and flow cytometric analysis. Following treatment with E7070, the cell cycle progression of P388 murine leukaemia cells was disturbed in the G1 phase. The cell-killing effect on human colon cancer HCT116 cells was found to be time-dependent. In the panel of 42 human tumour cell lines, E7070 showed an antitumour spectrum that was distinct from those of other anticancer drugs used in clinic. Animal tests using human tumour xenograft models demonstrated that E7070 could cause not only tumour growth suppression, but also tumour regression in three of five colorectal and two of two lung cancers. In the HCT116 xenograft model, E7070 was shown to be superior to 5-FU, MMC and CPT-11 (irinotecan). Furthermore, complete regression of advanced LX-1 tumours was observed in 80% of E7070-treated mice. All of these observations have promoted this drug to clinical evaluation.

Cell cycle regulation in the G1 phase: a promising target for the development of new chemotherapeutic anticancer agents

As a result of substantial advances in recent cancer biology, cell cycle regulation in the G1 phase has attracted a great deal of attention as a promising target for the research and treatment of cancer. Many of the important genes associated with G1 regulation have been shown to play a key role in proliferation, differentiation and oncogenic transformation and programmed cell death (apoptosis). Currently, a variety of "cytostatic" agents that affects G1 progression and/or G1/S transition are being evaluated in clinical trials. Flavopiridol is a potent inhibitor of cyclin-dependent kinases (CDKs). UCN-01 was originally found to be a PKC-selective protein kinase antagonist. More recent studies have revealed that this agent can also inhibit several CDKs and the checkpoint kinase CHK1. FR901228, MS-27-275 and SAHA are histone deacetylase inhibitors that induce changes in the transcription of specific genes via the hyperacetylation of histones. The proteasome inhibitor PS-341 disrupts the degradation process of intracellular proteins, including cell cycle regulatory proteins such as cyclins. R115777, SCH66336 and BMS-214662 are non-peptidic farnesyl transferase inhibitors that prevent p21 ras oncogene activation. Rapamycin derivative CCI-779 downregulates signals through S6 kinase and FRAP (FKBP-rapamycin associating protein), affecting the expression levels of mRNAs important for progression from G1 to S phase. 17-Allylaminogeldanamycin targets the Hsp-90 (heat shock protein-90) family of cellular chaperones regulating the function of signaling proteins. TNP-470 (AGM-1470), a fumagillin derivative shows antiangiogenic action through binding to MetAP-2 (methionine aminopeptidase-2). The antitumor sulfonamide E7070, causing a cellular accumulation in the G1 phase, has been shown to suppress the activation of CDK2 and cyclin E expression in HCT116 colorectal cancer cell line highly sensitive to the drug. With respect to several growth factor receptors such as EGFR, PDGFR, bFGFR and VEGFR, potent and specific inhibitors of receptor tyrosine kinases have been also examined as hopeful drug candidates. In this report, we review the current status of extensive efforts directed towards the discovery and development of new chemotherapeutic anticancer agents targeting cell cycle regulation in the G1 phase, with particular focus on the compounds undergoing clinical investigations.

An acoustically evoked short latency negative response in profound hearing loss patients

In our auditory brainstem response (ABR) tests, a peculiar V-shaped negative wave at around 3 4 ms latency was observed. At present, this acoustically evoked short latency negative response (ASNR) is poorly understood. In order to study its appearance and origin, the ABR data of 3104 tests during 1980-98 were reviewed. The ASNR was found only in profound hearing loss ears under intense stimuli (80-120 dB nHL). Out of the total 653 profound hearing loss patients (981 ears), the click-evoked ASNRs were present in 80 patients (12.3%), 117 ears (11.9%). The age range was from 8 months to 70 years. Demographic outcome revealed significant higher appearance rates in young subjects especially in the 20-30 years group. The ASNR was excluded from an artifact by its reproducibility over time, equipment and institutes. Moreover, it became absent after external auditory canal occlusion, which simply blocked the air conduction without any influence upon scalp potentials or equipment. It had neural response characteristics that the latency and amplitude shortened and increased respectively in response to the increase of stimulus intensity. Because the peculiar V-shaped waveform obviously differs from ABR, the ASNR was not interpreted as a potential generated from the conventional auditory pathway. On the other hand, the ASNR individuals were of good vestibular function in sharp contrast with their poor hearing. This suggests the probable relation between the ASNR and the vestibular system. The saccule and vestibular nucleus are hypothesized to be the sense organ and the origin of the response respectively.

A focused compound library of novel N-(7-indolyl)benzenesulfonamides for the discovery of potent cell cycle inhibitors

A series of compounds containing an N-(7-indolyl)benzenesulfonamide pharmacophore was synthesized and evaluated as a potential antitumor agent. Cell cycle analysis with P388 murine leukemia cells revealed that there were two different classes of potent cell cycle inhibitors; one disrupted mitosis and the other caused G1 accumulation. Herein described is the SAR summary of the substituent patterns on this pharmacophore template.