Ruzanna Atoyan

CUDC-101, a Multitargeted Inhibitor of Histone Deacetylase, Epidermal Growth Factor Receptor, and Human Epidermal Growth Factor Receptor 2, Exerts Potent Anticancer Activity

Receptor tyrosine kinase inhibitors have recently become important therapeutics for a variety of cancers. However, due to the heterogeneous and dynamic nature of tumors, the effectiveness of these agents is often hindered by poor response rates and acquired drug resistance. To overcome these limitations, we created a novel small molecule, CUDC-101, which simultaneously inhibits histone deacetylase and the receptor kinases epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) in cancer cells. Because of its integrated histone deacetylase inhibition, CUDC-101 synergistically blocked key regulators of EGFR/HER2 signaling pathways, also attenuating multiple compensatory pathways, such as AKT, HER3, and MET, which enable cancer cells to escape the effects of conventional EGFR/HER2 inhibitors. CUDC-101 displayed potent antiproliferative and proapoptotic activities against cultured and implanted tumor cells that are sensitive or resistant to several approved single-targeted drugs. Our results show that CUDC-101 has the potential to dramatically improve the treatment of heterogeneous and drug-resistant tumors that cannot be controlled with single-target agents. Further, they provide a framework to create individual small molecules that simultaneously antagonize multiple biochemically distinct oncogenic targets, suggesting a general paradigm to surpass conventional, single-target cancer therapeutics. Cancer Res; 70(9); 3647-56. (c)2010 AACR.

CUDC-305, a novel synthetic HSP90 inhibitor with unique pharmacologic properties for cancer therapy.

Purpose: We designed and synthesized CUDC-305, an HSP90 inhibitor of the novel imidazopyridine class. Here, we report its unique pharmacologic properties and antitumor activities in a variety of tumor types. Experimental Design: The potency of the compound was analyzed by fluorescence polarization competition binding assay. Its antiproliferative activities were assessed in 40 human cancer cell lines. Its pharmacologic properties and antitumor activities were evaluated in a variety of tumor xenograft models. Results: CUDC-305 shows high affinity for HSP90α/β (IC50, ∼100 nmol/L) and HSP90 complex derived from cancer cells (IC50, 48.8 nmol/L). It displays potent antiproliferative activity against a broad range of cancer cell lines (mean IC50, 220 nmol/L). CUDC-305 exhibits high oral bioavailability (96.0%) and selective retention in tumor (half-life, 20.4 hours) compared with normal tissues. Furthermore, CUDC-305 can cross blood-brain barrier and reach therapeutic levels in brain tissue. CUDC-305 exhibits dose-dependent antitumor activity in an s.c. xenograft model of U87MG glioblastoma and significantly prolongs animal survival in U87MG orthotopic model. CUDC-305 also displays potent antitumor activity in animal models of erlotinib-resistant non–small cell lung cancer and induces tumor regression in animal models of MDA-MB-468 breast cancer and MV4-11 acute myelogenous leukemia. Correlating with its efficacy in these various tumor models, CUDC-305 robustly inhibits multiple signaling pathways, including PI3K/AKT and RAF/MEK/ERK, and induces apoptosis. In combination studies, CUDC-305 enhances the antitumor activity of standard-of-care agents in breast and colorectal tumor models. Conclusion: CUDC-305 is a promising drug candidate for the treatment of a variety of cancers, including brain malignancies.

Cancer Network Disruption by a Single Molecule Inhibitor Targeting Both Histone Deacetylase Activity and Phosphatidylinositol 3-Kinase Signaling

Purpose: Given that histone deacetylase (HDAC) inhibitors are known to induce multiple epigenetic modifications affecting signaling networks and act synergistically with phosphatidylinositol 3-kinase (PI3K) inhibitors, we developed a strategy to simultaneously inhibit HDACs and PI3K in cancer cells. Experimental Design: We constructed dual-acting inhibitors by incorporating HDAC inhibitory functionality into a PI3K inhibitor pharmacophore. CUDC-907, a development candidate selected from these dual inhibitors, was evaluated in vitro and in vivo to determine its pharmacologic properties, anticancer activity, and mechanism of action. Results: CUDC-907 potently inhibits class I PI3Ks as well as classes I and II HDAC enzymes. Through its integrated HDAC inhibitory activity, CUDC-907 durably inhibits the PI3K-AKT-mTOR pathway and compensatory signaling molecules such as RAF, MEK, MAPK, and STAT-3, as well as upstream receptor tyrosine kinases. CUDC-907 shows greater growth inhibition and proapoptotic activity than single-target PI3K or HDAC inhibitors in both cultured and implanted cancer cells. Conclusions: CUDC-907 may offer improved therapeutic benefits through simultaneous, sustained disruption of multiple oncogenic signaling networks. Clin Cancer Res; 18(15); 4104–13. ©2012 AACR.

Targeting heat shock protein 90 with CUDC-305 overcomes erlotinib resistance in non–small cell lung cancer

CUDC-305 is a heat shock protein 90 (HSP90) inhibitor of the novel imidazopyridine class. Here, we report its activities in non–small cell lung cancer (NSCLC) cell lines with gene deregulations conferring primary or secondary resistance to epidermal growth factor receptor (EGFR) inhibitors. We show that CUDC-305 binds strongly to HSP90 extracted from erlotinib-resistant NSCLC cells (IC50 70 nmol/L). This result correlates well with the potent antiproliferative activity in erlotinib-resistant NSCLC cell lines (IC50 120–700 nmol/L) reported previously. Furthermore, it exhibits durable inhibition of multiple oncoproteins and induction of apoptosis in erlotinib-resistant NSCLC cells. CUDC-305 potently inhibits tumor growth in subcutaneous xenograft models of H1975 and A549, which harbor EGFR T790M mutation or K-ras mutations conferring acquired and primary erlotinib resistance, respectively. In addition, CUDC-305 significantly prolongs animal survival in orthotopic lung tumor models of H1975 and A549, which may be partially attributed to its preferential exposure in lung tissue. Furthermore, CUDC-305 is able to extend animal survival in a brain metastatic model of H1975, further confirming its ability to cross the blood-brain barrier. Correlating with its effects in various tumor models, CUDC-305 induces degradation of receptor tyrosine kinases and downstream signaling molecules of the PI3K/AKT and RAF/MEK/ERK pathways simultaneously, with concurrent induction of apoptosis in vivo. In a combination study, CUDC-305 enhanced the antitumor activity of a standard-of-care agent in the H1975 tumor model. These results suggest that CUDC-305 holds promise for the treatment of NSCLC with primary or acquired resistance to EGFR inhibitor therapy. [Mol Cancer Ther 2009;8(12):3296–306]

Potential advantages of CUDC-101, a multitargeted HDAC, EGFR, and HER2 inhibitor, in treating drug resistance and preventing cancer cell migration and invasion.

CUDC-101 is a novel, small-molecule, anticancer agent targeting histone deacetylase (HDAC), EGF receptor (EGFR), and HER2. It is currently in phase I clinical development in patients with solid tumors. Previously, we reported that CUDC-101 has potent antiproliferative and proapoptotic activity in cultured tumor cells and in vivo xenograft models. We now show that cancer cells that have acquired resistance to single-target EGFR inhibitors through upregulation of AXL or loss of E-cadherin remain sensitive to CUDC-101, which inhibits MET- and AXL-mediated signaling, restores E-cadherin expression, and reduces cell migration. CUDC-101 also efficiently inhibited the proliferation of MET-overexpressing non–small cell lung cancer and gastric cancer cell lines and inhibited the migration and invasion of invasive tumor cells. Taken together, these results suggest that coupling HDAC and HER2 inhibitory activities to an EGFR inhibitor may potentially be effective in overcoming drug resistance and preventing cancer cell migration. Mol Cancer Ther; 12(6); 925–36. ©2013 AACR.

A Phase I Study of CUDC-101, a Multitarget Inhibitor of HDACs, EGFR, and HER2, in Combination with Chemoradiation in Patients with Head and Neck Squamous Cell Carcinoma

Purpose: CUDC-101 is a small molecule that simultaneously inhibits the epidermal growth factor receptor (EGFR), human growth factor receptor 2 (HER2), and histone deacetylase (HDAC) with preclinical activity in head and neck squamous cell cancer (HNSCC). The primary objective of this investigation is to determine the maximum tolerated dose (MTD) of CUDC-101 with cisplatin–radiotherapy in the treatment of HNSCC. Experimental Design: CUDC-101 monotherapy was administered intravenously three times weekly (Monday, Wednesday, Friday) for a one-week run-in, then continued with concurrent cisplatin (100 mg/m2 every 3 weeks) and external beam radiation (70 Gy to gross disease) over 7 weeks. Results: Twelve patients with intermediate or high-risk HNSCC enrolled. Eleven were p16INKa (p16)-negative. The MTD of CUDC-101–based combination therapy was established at 275 mg/m2/dose. Five patients discontinued CUDC-101 due to an adverse event (AE); only one was considered a dose-limiting toxicity (DLT), at the MTD. Pharmacokinetic evaluation suggested low accumulation with this dosing regimen. HDAC inhibition was demonstrated by pharmacodynamic analyses in peripheral blood mononuclear cells (PBMC), tumor biopsies, and paired skin biopsies. Paired tumor biopsies demonstrated a trend of EGFR inhibition. At 1.5 years of median follow-up, there has been one recurrence and two patient deaths (neither attributed to CUDC-101). The remaining nine patients are free of progression. Conclusions: CUDC-101, cisplatin, and radiation were feasible in intermediate-/high-risk patients with HNSCC, with no unexpected patterns of AE. Although the MTD was identified, a high rate of DLT-independent discontinuation of CUDC-101 suggests a need for alternate schedules or routes of administration. Clin Cancer Res; 21(7); 1566–73. ©2015 AACR.

Dual HDAC and PI3K Inhibitor CUDC-907 Downregulates MYC and Suppresses Growth of MYC-dependent Cancers.

Upregulation of MYC is a common driver event in human cancers, and some tumors depend on MYC to maintain transcriptional programs that promote cell growth and proliferation. Preclinical studies have suggested that individually targeting upstream regulators of MYC, such as histone deacetylases (HDAC) and phosphoinositide 3-kinases (PI3K), can reduce MYC protein levels and suppress the growth of MYC-driven cancers. Synergy between HDAC and PI3K inhibition in inducing cancer cell death has also been reported, but the involvement of MYC regulation is unclear. In this study, we demonstrated that HDAC and PI3K inhibition synergistically downregulates MYC protein levels and induces apoptosis in “double-hit” (DH) diffuse large B-cell lymphoma (DLBCL) cells. Furthermore, CUDC-907, a small-molecule dual-acting inhibitor of both class I and II HDACs and class I PI3Ks, effectively suppresses the growth and survival of MYC-altered or MYC-dependent cancer cells, such as DH DLBCL and BRD–NUT fusion-positive NUT midline carcinoma (NMC) cells, and MYC protein downregulation is an early event induced by CUDC-907 treatment. Consistently, the antitumor activity of CUDC-907 against multiple MYC-driven cancer types was also demonstrated in animal models, including DLBCL and NMC xenograft models, Myc transgenic tumor syngeneic models, and MYC-amplified solid tumor patient-derived xenograft (PDX) models. Our findings suggest that dual function HDAC and PI3K inhibitor CUDC-907 is an effective agent targeting MYC and thus may be developed as potential therapy for MYC-dependent cancers. Mol Cancer Ther; 16(2); 285–99. ©2016 AACR.

Abstract 3744: Antitumor activity of CUDC-907, a dual PI3K and HDAC inhibitor, in hematological cancer models

Recent evidence indicates that both PI3K-Akt-mTOR signaling pathway and HDAC are validated targets in hematological cancers. In order to overcome primary resistance and prevent secondary resistance resulting from compensatory/feedback mechanisms in cancer cells, CUDC-907 was designed to inhibit all isoforms of Class I PI3K and Class I and II HDAC, based on previous observations that synergistic effects can be achieved by inhibition of both HDAC and PI3K in cancer cells. In cell proliferation assays, this compound displays potent anti-proliferation activity in hematological cancer cell lines including non-Hodgkin9s lymphoma (NHL), and multiple myeloma (MM). Mechanistically, CUDC-907 is able to simultaneously suppress PI3K-Akt-mTOR as well as other essential signaling pathways due to epigenetic modifications via HDAC inhibition. CUDC-907 is orally bio-available in dogs, has a long half-life in murine tumors, induces apoptosis and inhibits cancer cell proliferation in xenograft tumors. In efficacy studies in NHL and MM models, CUDC-907 is more efficacious than either a single-agent PI3K or HDAC inhibitor reference compound or a combination of the two agents given at maximally tolerated doses (MTD). Furthermore, CUDC-907 is more efficacious than the PI3Kα-selective inhibitor CAL-101 when dosed at MTD doses. These observations are related to our findings that, all isoforms of PI3K are expressed in most hematological cancer models. Therefore, the efficacy of isoform selective PI3K inhibitors may be limited only to those cancers driven by a specific PI3K subtype. In addition, a synergistic antitumor effect can be achieved in efficacy studies when CUDC-907 is combined with standard of care agents in both NHL and MM models. In conclusion, through broad network disruption, CUDC-907 may offer a greater therapeutic benefit than isoform-specific PI3K inhibitors as a novel anti-cancer treatment of hematological malignancies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3744. doi:1538-7445.AM2012-3744

Abstract 1879: Dual function HDAC and PI3K inhibitor, CUDC-907 affects cancer cells and the tumor microenvironment in hematological malignancies

Histone deacetylases (HDACs) and the phosphatidylinositol 3-kinase (PI3K)/AKT pathway are promising therapeutic targets in hematologic cancers and evidence of synergistic anti-cancer activity has recently emerged. CUDC-907, a small molecule drug candidate that is designed to target HDACs and PI3Ks in a single chemical entity, is currently in Phase 1 clinical testing for the treatment of patients with lymphoma or multiple myeloma. Preclinically, CUDC-907 has been shown to inhibit activation of PI3K/AKT, JAK/STAT and MAPK pathways in hematologic cancer cell lines such as Hodgkin9s lymphoma, diffuse large B-cell lymphoma, and multiple myeloma. In this study, we report that in the setting of hematological malignancies, CUDC-907 targets not only the cancer cells but also the tumor microenvironment. Cytotoxicity against primary CLL cells was independent of the protective effects provided by stromal cells when primary CLL cells were co-cultured with nurse-like cells. CUDC-907 was shown in vitro to impair cytokine and chemokine production by immune cells in the tumor microenvironment and by Hodgkin9s lymphoma cells. The ongoing first-in-human Phase 1 clinical study of CUDC-907 has yielded preliminary evidence of anti-cancer activity and impact on the tumor microenvironment as measured by cytokine and chemokine levels (e.g., thymus and activation regulated chemokine [TARC]). Ongoing analyses are probing the potential utility of selected cytokine and chemokine as predictive markers of CUDC-907 activity. Citation Format: Anna W. Ma, Ruzanna Atoyan, Anas Younes, Ian W. Flinn, Yasuhiro Oki, Amanda Copeland, Jesus G. Berdeja, Robert Laliberte, Jaye Viner, Maria Elena S. Samson, Steven Dellarocca, Ling Yi, Mylissa Borek, Brian Zifcak, Guangxin Xu, Jing Wang. Dual function HDAC and PI3K inhibitor, CUDC-907 affects cancer cells and the tumor microenvironment in hematological malignancies. [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 1879. doi:10.1158/1538-7445.AM2014-1879

Abstract 4634: Novel dual HDAC & PI3K inhibitor, CUDC-907, for MYC-driven malignancies

MYC family genes are among the most frequently deregulated oncogenic drivers in human cancer. Pharmacologic inhibition of HDAC activity and blockade of the PI3K pathway have both been shown to suppress MYC-induced transcription. HDAC activity is critical for MYC gene regulation, as MYC represses transcription of target genes through recruitment of HDACs. HDAC inhibitors have been shown to restore expression of genes suppressed by MYC family members and to induce rapid downregulation of expression of MYC itself. The PI3K pathway plays a central role in regulating MYC at the post-transcriptional level. Activation of PI3K signaling leads to activation of AKT, which phosphorylates and inhibits GSK3β. As GSK3β normally phosphorylates MYC which facilitates the degradation of MYC, activation of PI3K signaling leads to increased stability of MYC, whereas PI3K inhibitors decrease MYC stability. A recent study has demonstrated addiction to MYC signaling and hypersensitivity to PI3K inhibition in PTEN-deficient diffuse large B-cell (DLBCL) cell lines, suggesting that MYC-driven cancers may be particularly sensitive to PI3K inhibition. As HDACs and PI3K regulate MYC protein levels and functions through nonoverlapping mechanisms, simultaneous HDAC and PI3K inhibition may further enhance MYC suppression. CUDC-907 is an orally bioavailable, small-molecule dual HDAC and PI3K inhibitor that primarily inhibits class I and II HDACs and the PI3Kα, β, and δ isoforms. CUDC-907 shows greater anti-tumor activity in vitro than single-target HDAC or PI3K inhibitors, especially in MYC-dependent cell types, such as DLBCL and NUT midline carcinoma (NMC). In preclinical testing, CUDC-907 treatment leads to a dose-dependent decrease in MYC protein levels, and is also more potent in decreasing MYC than the HDAC inhibitor panobinostat and the pan-PI3K inhibitor pictilisib alone or in combination. Significant antitumor effects have been consistently observed in MYC-driven DLBCL xenograft and genetically engineered mouse models exposed to CUDC907. In particular, certain MYC translocation (Daudi), double-hit (concurrent MYC and BLC2 translocation, WSUDLCL2 and DOHH2), double-expresser (expression of MYC and BCL2 proteins, U2932) xenograft models, and the Eμ-Myc transgenic mouse model achieve tumor growth inhibition of 100%, 69%, 56%, 97% and 72%, respectively. These findings raise the possibility that hematologic and solid tumors driven by aberrant overexpression of MYC family genes (e.g., MYC-altered DLBCL and NMC) might be more responsive to simultaneous HDAC and PI3K inhibition with CUDC-907 than they are to single-target therapy. Clinical Phase 1 studies are currently testing CUDC-907 in patients with relapsed/refractory (R/R) DLBCL and advanced MYC-aberrant solid tumors. Preliminary data are encouraging and support the planned Phase 2 study in R/R MYC-altered DLBCL, as well as further testing in other MYC-driven malignancies. Citation Format: Kaiming Sun, Ruzanna Atoyan, Mylissa A. Borek, Steven Dellarocca, Maria E. Samson, Anna W. Ma, Guangxin Xu, Troy Patterson, David P. Tuck, Jaye L. Viner, Ali Fattaey, Jing Wang. Novel dual HDAC & PI3K inhibitor, CUDC-907, for MYC-driven malignancies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4634.