Gottardis, Marco M.

Abstract Abstract 4112 We report the characterization of BMS-911543, a potent and functionally selective small molecule inhibitor of the Janus kinase family (JAK) member, JAK2. BMS-911543 is a reversible inhibitor of JAK2 with a biochemical IC50 of 0.001 μ M and Ki of 0.48 nM. It has over 74- and 350-fold selectivity against the other JAK family members, JAK3 and JAK1, respectively. Further, examination of > 450 other kinases did not reveal significant inhibitory activity for this JAK2 inhibitor. Functionally, BMS-911543 displayed potent anti-proliferative and pharmacodynamic (PD) effects in mutated JAK2-expressing cell lines dependent upon JAK2-STAT signaling and had little activity in cell types dependent upon other pathways such as JAK1 and JAK3. BMS-911543 was evaluated in colony growth assays using primary progenitor cells isolated from patients with JAK2V617F-positive myeloproliferative disease (MPD) and resulted in an increased anti-proliferative response in MPD cells as compared with those from healthy volunteers. Similar to these in vitro observations, BMS-911543 was also highly active in in vivo models of JAK2-pSTAT signaling in multiple species (mouse, rat, dog and monkey) with sustained pathway suppression being observed after a single oral dose. Additionally, BMS-911543 was evaluated for effects in a JAK2V617F-expressing SET-2 xenograft model system and displayed a minimally effective dose of <2 mg/kg on pSTAT5 pathway suppression, which lasted up to 8 hours. BMS-911543 was also compared to pan-JAK inhibitors in a mouse model of immunosuppression. At low dose levels active in JAK2-dependent PD models, no effects were observed on antigen-induced IgG and IgM production whereas a pan-JAK family inhibitor showed pronounced effects at all dose levels tested. The mechanistic selectivity of BMS-911543 to pan-JAK family inhibitors was extended through comparative analysis of these inhibitors in whole genome gene expression profiling experiments performed in sensitive cell types. In this comparison, BMS-911543 modulated a distinct subset of transcriptional changes as compared to pan-JAK inhibitors, thereby defining a minimal set of transcriptional changes underlying the pharmacologic effects of JAK2 inhibition. Collectively these results define the mechanistic basis for a differential therapeutic index between selective JAK2 and pan-JAK family inhibition pre-clinically and suggest a therapeutic rationale for the further characterization of BMS-911543 in patients with MPD and in other disorders characterized by constitutively active JAK2 signaling. Disclosures: Purandare: Bristol-Myers Squibb: Employment. McDevitt:Bristol-Myers Squibb: Employment. Gottardis:Bristol-Myers Squibb: Employment. You:Bristol-Myers Squibb: Employment. Lombardo:Bristol_Myers Squibb: Employment. Penhallow:Bristol-Myers Squibb: Employment. Vuppugalla:Bristol-Myers Squibb: Employment. Trainor:Bristol-Myers Squibb: Employment. Lorenzi:Bristol-Myers Squibb: Employment.

Abstract Myeloproliferative diseases (MPDs) are a subset of myeloid malignancies that are characterized by the expansion of a multipotent hematopoietic stem cell. Chronic MPDs can be classified into two categories, those harboring the BCR-ABL oncogene and those that are negative. This later category of neoplasms encompasses polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Recent discovery of activating mutations in the tyrosine kinase gene, JAK2 and constitutive activation of JAK2-STAT pathway, in large number of MPD patients has ignited considerable interest in MPD and has highlighted JAK2 as a therapeutic intervention point for drug discovery efforts. However, high-sequence homology with other JAK family members has posed a major challenge to design selective JAK2 inhibitors. Given that other JAK family members are involved in the regulation of immune function, it is important to maintain selectivity for JAK2 over these family members in order to mitigate the risks associated with undesired immunosuppression. Several JAK2 inhibitors with varying selectivity profiles are currently being evaluated in preclinical testing as well as in clinical trials for the treatment of MPD. Additionally, emerging genetic and pharmacologic evidence suggest that inhibition of the JAK2-STAT pathway may be an important therapeutic intervention point in other hematological malignancies as well as in certain solid tumors. We report here the discovery and characterization of BMS-911543, a functionally selective small molecule inhibitor of the Janus kinase family (JAK) member, JAK2. BMS-911543 is a potent and reversible inhibitor of JAK2 with a biochemical Ki of 0.48 nM. It has over 65-, 74- and 350-fold selectivity against the other JAK family members, TYK2, JAK3 and JAK1, respectively. Importantly, examination of &gt; 450 other kinases in competition binding assays and in selected biochemical kinase assays did not reveal significant inhibitory activity for this JAK2 inhibitor, highlighting its high degree of biochemical selectivity for JAK2. Functionally, BMS-911543 displayed potent antiproliferative and pharmacodynamic (PD) effects in mutated JAK2-expressing cell lines dependent upon JAK2-STAT signaling and had little activity in cell types dependent upon other pathways such as JAK1 and JAK3. Further, single agent antiproliferative activity was not observed for BMS-911543 in a variety of solid tumor cell lines dependent upon other signaling pathways. In contrast, BMS-911543 was evaluated in colony growth assays using primary progenitor cells isolated from patients with JAK2V617F-positive myeloproliferative disease (MPD) and resulted in an increased antiproliferative response in MPD cells as compared with those from healthy volunteers. Similar to these in vitro observations, BMS-911543 was also highly active in in vivo models of JAK2-pSTAT signaling in multiple species with durable and potent pathway suppression observed after a single oral dose. Additionally, BMS-911543 was evaluated for effects in a JAK2V617F-expressing SET-2 xenograft model system and displayed a minimally effective dose of &lt;2 mg/kg on pSTAT5 pathway suppression, which lasted up to 8 hours. To test the hypothesis that a JAK2 selective inhibitor would have less effect on immune system function, BMS-911543 was compared to pan-JAK inhibitors in a mouse model of immunosuppression. At low dose levels active in JAK2-dependent PD models, no effects were observed on antigen-induced IgG and IgM production for BMS-911543 whereas a pan-JAK family inhibitor showed pronounced effects at all dose levels tested. The mechanistic selectivity of BMS-911543 to pan-JAK family inhibitors was extended through comparative analysis of these inhibitors in whole genome gene expression profiling experiments performed in sensitive and resistant cell types. In this comparison, BMS-911543 modulated a distinct subset of transcriptional changes as compared to pan-JAK inhibitors in clinical testing, thereby defining a minimal set of transcriptional changes underlying the pharmacologic effects of JAK2 inhibition. Collectively these results define the mechanistic basis for a differential therapeutic index between selective JAK2 and pan-JAK family inhibition pre-clinically and suggest a therapeutic rationale for the further characterization of BMS-911543 in patients with MPD and in other malignancies reliant upon constitutively active JAK2 signaling. References: Levine, R.L., et al. Role of JAK2 in the pathogenesis and therapy of myeloproliferative disorders (2007). Nature Rev. Cancer, 7, 673-683. Atallah, E. and Verstovsek, S. Prospect of JAK2 inhibitor therapy in myeloproliferative neoplasms. (2009). Expert Rev. Anticancer Ther. 9, 663-670. Ghoreschi, K., et al. Janus kinases in immune cell signaling. (2009). Immunol. Rev.,228, 273-287. Mesa, R.A. and Tefferi, A. Emerging drugs for the therapy of primary and post essential thrombocythemia, post polycythemia vera myelofibrosis (2009). Expert Opin. Emerging Drugs, 14, 1-9. Roll, J.D. and Reuther, G.W. CRLF2 and JAK2 in B-progenitor acute lymphoblastic leukemia: a novel association in oncogenesis. (2010) Cancer Res, 70, 7347-7352. Rui et al., Cooperative epigenetic modulation by cancer amplicon genes (2010). Cancer Cell, 18, 590-605. 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 DDT01-03. doi:10.1158/1538-7445.AM2011-DDT01-03

Abstract Purpose: To improve the significance of insulin-like growth factor–binding protein 5 (IGFBP-5) as a prognostic and potentially predictive marker in patients with breast cancer. Experimental Design: Increased IGFBP-5 expression was identified in MCF-7 cells resistant (MCF-7R4) to the IGF-1R/insulin receptor (InsR) inhibitor BMS-536924 and its role examined by targeted knockdown and overexpression in multiple experimental models. Protein expression of IGFBP-5 was measured by immunohistochemistry in a cohort of 76 patients with breast cancer to examine correlative associations with invasive tumor fraction and outcome. The use of a combined IGFBP-5/IGFBP-4 (BPR) expression ratio was applied to predict anti-IGF-1R/InsR response in a panel of breast cancer lines and outcome in multiple breast tumor cohorts. Results: IGFBP-5 knockdown decreased BMS-536924 resistance in MCF-7R4 cells, whereas IGFBP-5 overexpression in MCF-7 cells conferred resistance. When compared with pathologically normal reduction mammoplasty tissue, IGFBP-5 expression levels were upregulated in both invasive and histologically normal adjacent breast cancer tissue. In both univariate and multivariate modeling, metastasis-free survival, recurrence free survival (RFS), and overall survival (OS) were significantly associated with high IGFBP-5 expression. Prognostic power of IGFBP-5 was further increased with the addition of IGFBP-4 where tumors were ranked based upon IGFBP-5/IGFBP-4 expression ratio (BPR). Multiple breast cancer cohorts confirm that BPR (high vs. low) was a strong predictor of RFS and OS. Conclusion: IGFBP-5 expression is a marker of poor outcome in patients with breast cancer. An IGFBP-5/IGFBP-4 expression ratio may serve as a surrogate biomarker of IGF pathway activation and predict sensitivity to anti-IGF-1R targeting. Clin Cancer Res; 18(6); 1808–17. ©2012 AACR.

Abstract Insulin-like growth factor (IGF) signaling has been implicated in the resistance to hormonal therapy in breast cancer. Using a model of postmenopausal, estrogen-dependent breast cancer, we investigated the antitumor effects of the dual IGF-1R/InsR tyrosine kinase inhibitor BMS-754807 alone and in combination with letrozole or tamoxifen. BMS-754807 exhibited antiproliferative effects in vitro that synergized strongly in combination with letrozole or 4-hydroxytamoxifen and fulvestrant. Similarly, combined treatment of BMS-754807 with either tamoxifen or letrozole in vivo elicited tumor regressions not achieved by single-agent therapy. Notably, hormonal therapy enhanced the inhibition of IGF-1R/InsR without major side effects in animals. Microarray expression analysis revealed downregulation of cell-cycle control and survival pathways and upregulation of erbB in response to BMS-754807 plus hormonal therapy, particularly tamoxifen. Overall, these results offer a preclinical proof-of-concept for BMS-754807 as an antitumor agent in combination with hormonal therapies in hormone-sensitive breast cancer. Cooperative cell-cycle arrest, decreased proliferation, and enhanced promotion of apoptosis may contribute to antitumor effects to be gauged in future clinical investigations justified by our findings. Cancer Res; 71(24); 7597–607. ©2011 AACR.

Abstract Preclinical investigations have identified insulin-like growth factor (IGF) signaling as a key mechanism for cancer growth and resistance to clinically useful therapies in multiple tumor types including breast cancer. Thus, agents targeting and blocking IGF signaling have promise in the treatment of solid tumors. To identify possible mechanisms of resistance to blocking the IGF pathway, we generated a cell line that was resistant to the IGF-1R/InsR benzimidazole inhibitors, BMS-554417 and BMS-536924, and compared expression profiles of the parental and resistant cells lines using Affymetrix GeneChip Human Genome U133 arrays. Compared with MCF-7 cells, breast cancer resistance protein (BCRP) expression was increased 9-fold in MCF-7R4, which was confirmed by immunoblotting and was highly statistically significant (P = 7.13E-09). BCRP was also upregulated in an independently derived resistant cell line, MCF-7 924R. MCF-7R4 cells had significantly lower intracellular accumulation of BMS-536924 compared with MCF-7 cells. Expression of BCRP in MCF-7 cells was sufficient to reduce sensitivity to BMS-536924. Furthermore, knockdown of BCRP in MCF-7R4 cells resensitized cells to BMS-536924. Four cell lines selected for resistance to the pyrrolotriazine IGF-1R/InsR inhibitor, BMS-754807, did not have upregulation of BCRP. These data suggest that benzimidazole IGF-1R/InsR inhibitors may select for upregulation and be effluxed by the ATP-binding cassette transporter, BCRP, contributing to resistance. However, pyrrolotriazine IGF-1R/InsR inhibitors do not appear to be affected by this resistance mechanism. Mol Cancer Ther; 10(1); 117–25. ©2011 AACR.

Abstract Resistance to hormonal therapy is a clinically unmet need in breast cancer. IGF signaling has been identified as a major mechanism of resistance to hormonal therapy in breast cancer. As components of the IGF signaling pathway are expressed in most breast cancers, the development of IGF-1R monoclonal antibody (mAb) and tyrosine kinase inhibitors (TKI) are active areas of clinical investigations. A key distinction between the mAb and TKIs are their differences in their ability to inhibit the Insulin Receptor (InsR). While targeting the InsR with TKIs may have a theoretical liability of hyperglycemia, targeting only the IGF-1R may have the theoretical liability of incompletely blocking IGF signaling. As InsR isoform A expression, which can transduce IGF-II-mediated proliferation, is higher in breast cancers compared to normal breast tissue, we investigated whether IGF-1R or IGF-1R/InsR inhibition was sufficient for overcoming resistance to hormonal therapy. To determine the optimal combination strategies for clinical investigations, we tested the hypothesis that IGF signaling inhibition could overcome primary (or de novo/intrinsic) and secondary (or acquired/selected) resistance to hormonal therapy. For these studies, we used either hormone therapy-naïve or hormone therapy-resistant variants of the breast cancer model, MCF-7/AC-1, which has been engineered to stably express full-length human aromatase. We employed and compared a novel, potent dual kinase inhibitor of the IGF-1R and InsR, BMS-754807, which is currently in early clinical investigations, with the IGF-1R antibody mAb391. BMS-754807 has been shown to induce apoptosis more potently than mAb391 in Rh41 human rhabdomyosarcoma cells. In vitro, BMS-754807 demonstrated profound synergy in combination with tamoxifen and letrozole (median effect combination index &lt;0.1). In vivo, BMS-754807 enhanced the anti-tumor activity of tamoxifen and letrozole in hormone-naïve tumors and induced regression of tumors resistant to tamoxifen or letrozole when combined with letrozole. This activity was not observed with mAb therapy, which resulted in greater up-regulation of InsR-A and erbB receptor expression and activation. This suggested a greater susceptibility to resistance pathways with mAb therapy. Dual IGF-1R/InsR blockade alone or in combination was tolerated by the animals and has no significant change in glucose homeostasis. Gene expression profiling experiments to compare the difference between the effects of tamoxifen in combination with BMS-754807 and with mAb revealed alternative pathway signaling is one of the potential mechanisms of resistance.In summary, combined hormonal therapy with BMS-754807 overcomes primary and secondary resistance to tamoxifen and letrozole and was well tolerated. IGF-1R blockade with a mAb alone is insufficient to overcome resistance and induces InsR over-expression. Thus, IGF signaling through either InsR or IGF-1R may be a major mechanism of resistance to hormonal therapy. These data suggest that blockade of IGF-1 and IGF-II from activation of IGF-1R and InsR, with agents such as BMS-754807 have promise in extending the benefits of hormonal therapy in breast cancer. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 402.

Abstract The insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R) are receptor tyrosine kinases that participate in mitogenic and antiapoptotic signaling in normal and neoplastic epithelia. In the present study, immunoblotting and reverse transcription-PCR demonstrated expression of IGF1R and IR isoform A in acute myelogenous leukemia (AML) cell lines as well as in &gt;80% of clinical AML isolates. Treatment with insulin enhanced signaling through the Akt and MEK1/2 pathways as well as survival of serum-starved AML cell lines. Conversely, treatment with BMS-536924, a dual IGF1R/IR kinase inhibitor that is undergoing preclinical testing, inhibited constitutive receptor phosphorylation as well as downstream signaling through MEK1/2 and Akt. These changes inhibited proliferation and, in some AML cell lines, induced apoptosis at submicromolar concentrations. Likewise, BMS-536924 inhibited leukemic colony formation in CD34+ clinical AML samples in vitro. Collectively, these results not only indicate that expression of IGF1R and IR isoform A is common in AML but also show that interruption of signaling from these receptors inhibits proliferation in clinical AML isolates. Accordingly, further investigation of IGF1R/IR axis as a potential therapeutic target in AML appears warranted. [Cancer Res 2009;69(19):7635–43]

Abstract We have reported previously the activity of the insulin-like growth factor-I (IGF-IR)/insulin receptor (InsR) inhibitor, BMS-554417, in breast and ovarian cancer cell lines. Further studies indicated treatment of OV202 ovarian cancer cells with BMS-554417 increased phosphorylation of HER-2. In addition, treatment with the pan-HER inhibitor, BMS-599626, resulted in increased phosphorylation of IGF-IR, suggesting a reciprocal cross-talk mechanism. In a panel of five ovarian cancer cell lines, simultaneous treatment with the IGF-IR/InsR inhibitor, BMS-536924 and BMS-599626, resulted in a synergistic antiproliferative effect. Furthermore, combination therapy decreased AKT and extracellular signal-regulated kinase activation and increased biochemical and nuclear morphologic changes consistent with apoptosis compared with either agent alone. In response to treatment with BMS-536924, increased expression and activation of various members of the HER family of receptors were seen in all five ovarian cancer cell lines, suggesting that inhibition of IGF-IR/InsR results in adaptive up-regulation of the HER pathway. Using MCF-7 breast cancer cell variants that overexpressed HER-1 or HER-2, we then tested the hypothesis that HER receptor expression is sufficient to confer resistance to IGF-IR-targeted therapy. In the presence of activating ligands epidermal growth factor or heregulin, respectively, MCF-7 cells expressing HER-1 or HER-2 were resistant to BMS-536924 as determined in a proliferation and clonogenic assay. These data suggested that simultaneous treatment with inhibitors of the IGF-I and HER family of receptors may be an effective strategy for clinical investigations of IGF-IR inhibitors in breast and ovarian cancer and that targeting HER-1 and HER-2 may overcome clinical resistance to IGF-IR inhibitors. [Mol Cancer Ther 2008;7(9):2589–98]

Abstract The insulin-like growth factor receptor (IGF-IR) and insulin receptor are either overactivated and/or overexpressed in a wide range of tumor types and contribute to tumorigenicity, proliferation, metastasis, and drug resistance. Here, we show that BMS-554417, a novel small molecule developed as an inhibitor of IGF-IR, inhibits IGF-IR and insulin receptor kinase activity and proliferation in vitro, and reduces tumor xenograft size in vivo. In a series of carcinoma cell lines, the IC50 for proliferation ranged from 120 nmol/L (Colo205) to &gt;8.5 μmol/L (OV202). The addition of stimulatory ligands was unnecessary for the antiproliferative effect in MCF-7 and OV202 cells. BMS-554417 treatment inhibited IGF-IR and insulin receptor signaling through extracellular signal-related kinase as well as the phosphoinositide 3-kinase/Akt pathway, as evidenced by decreased Akt phosphorylation at Ser473. At doses that inhibited proliferation, the compound also caused a G0-G1 arrest and prevented nuclear accumulation of cyclin D1 in response to LR3 IGF-I. In Jurkat T-cell leukemia cells, this agent triggered apoptotic cell death via the mitochondrial pathway. BMS-554417 was orally bioavailable and significantly inhibited the growth of IGF1R-Sal tumor xenografts in vivo. BMS-554417 is a member of a novel class of IGF-IR/insulin receptor inhibitors that have potential clinical applications because of their antiproliferative and proapoptotic activity in vitro and in vivo. (Cancer Res 2006; 66(1): 362-71)