Immune and pathologic responses in patients with localized prostate cancer who received daratumumab (anti-CD38) or edicotinib (CSF-1R inhibitor)

BACKGROUND

The prostate tumor microenvironment (TME) is immunosuppressive, with few effector T cells and enrichment of inhibitory immune populations, leading to limited responses to treatments such as immune checkpoint therapies (ICTs). The immune composition of the prostate TME differs across soft tissue and bone, the most common site of treatment-refractory metastasis. Understanding immunosuppressive mechanisms specific to prostate TMEs will enable rational immunotherapy strategies to generate effective antitumor immune responses. Daratumumab (anti-CD38 antibody) and edicotinib (colony-stimulating factor-1 receptor (CSF-1R) inhibitor) may alter the balance within the prostate TME to promote antitumor immune responses.

HYPOTHESIS

Daratumumab or edicotinib will be safe and will alter the immune TME, leading to antitumor responses in localized prostate cancer.

PATIENTS AND METHODS

In this presurgical study, patients with localized prostate cancer received 4 weekly doses of daratumumab or 4 weeks of daily edicotinib prior to radical prostatectomy (RP). Treated and untreated control (Gleason score ≥8 in prostate biopsy) prostatectomy specimens and patient-matched pre- and post-treatment peripheral blood mononuclear cells (PBMCs) and bone marrow samples were evaluated. The primary endpoint was incidence of adverse events (AEs). The secondary endpoint was pathologic complete remission (pCR) rate.

RESULTS

Twenty-five patients were treated (daratumumab, n=15; edicotinib, n=10). All patients underwent RP without delays. Grade 3 treatment-related AEs with daratumumab occurred in 3 patients (12%), and no ≥grade 3 treatment-related AEs occurred with edicotinib. No changes in serum prostate-specific antigen (PSA) levels or pCRs were observed. Daratumumab led to a decreased frequency of CD38+ T cells, natural killer cells, and myeloid cells in prostate tumors, bone marrow, and PBMCs. There were no consistent changes in CSF-1R+ immune cells in prostate, bone marrow, or PBMCs with edicotinib. Neither treatment induced T cell infiltration into the prostate TME.

CONCLUSIONS

Daratumumab and edicotinib treatment was safe and well-tolerated in patients with localized prostate cancer but did not induce pCRs. Decreases in CD38+ immune cells were observed in prostate tumors, bone marrow, and PBMCs with daratumumab, but changes in CSF-1R+ immune cells were not consistently observed with edicotinib. Neither myeloid-targeted agent alone was sufficient to generate antitumor responses in prostate cancer; thus, combinations with agents to induce T cell infiltration (eg, ICTs) will be needed to overcome the immunosuppressive prostate TME.

Abstract 2179: Antitumor activity of JNJ-63576253 (TRC253), a small molecule antagonist of F877L mutant and wild-type androgen receptor

Androgen receptor (AR) antagonists have transformed prostate cancer patient care by targeting a key nodal point in tumor cell signaling. However, despite the impressive clinical activity of first- and second-generation antiandrogens, acquired resistance frequently emerges. Point mutations in the ligand-binding domain of AR, such as phenylalanine to leucine at position 877 (ARF877L), account for 10-20% of resistance. Such mutations are characterized by receptor activation, rather than inhibition, by first- and second-generation antiandrogen therapeutics.

JNJ-63576253 is a potent, high affinity competitive binder of wild type and mutant AR, including F877L. JNJ-63576253 blocks AR nuclear translocation, AR binding to DNA, and AR-dependent transcription. JNJ-63576253 inhibits the proliferation of androgen receptor driven prostate cancer cell lines, including those bearing ARF877L.

In the Hershberger assay in male Sprague Dawley rats, oral administration of JNJ-63576253 inhibited androgen sensitive organ (ASO) development in a dose-dependent manner. In male SHO mice bearing LNCaP xenografts with either wild-type or ARF877L, daily treatment with 30 mg/kg JNJ-63576253 treatment resulted in statistically significant antitumor activity, whereas second-generation antiandrogen enzalutamide had no antitumor efficacy in the LNCaP ARF877L mutant model.

Janssen and Tracon Pharma have entered a strategic licensing collaboration, whereby Tracon possesses exclusive rights for clinical development of JNJ-63576253 (now called TRC253). Tracon has entered TRC253 into Ph1/2A clinical evaluation in metastatic castration-resistant prostate cancer patients.

Citation Format: Tammy L. Bush, Georges Habineza Ndikuyeze, Gilles Bignan, Jonathan Branch, Janine Ondrus, Yifan Shi, Leopoldo Luistro, James Hastings, Joseph Erhardt, Ian Hickson, Shefali Patel, Peter Connolly, Zhuming Zhang, James Bischoff, Brent Rupnow, Marco Gottardis, Kathryn Packman. Antitumor activity of JNJ-63576253 (TRC253), a small molecule antagonist of F877L mutant and wild-type androgen receptor [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 2179.

Safety and preliminary immunogenicity of JNJ-64041809, a live attenuated, double-deleted Listeria monocytogenes-based immunotherapy, in metastatic castration-resistant prostate cancer (mCRPC)

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Background: The safety and immunogenicity of JNJ-64041809 (JNJ-809), a live attenuated, double-deleted Listeria monocytogenes (LADD- Lm)-based immunotherapy targeting relevant prostate cancer antigens, was evaluated in a phase 1, multicenter, open-label study in patients (pts) with mCRPC. Methods: Men aged ≥18 years with progressive mCRPC who had received ≥2 prior approved therapies were included. The recommended phase 2 dose (RP2D) and the safety and immunogenicity of JNJ-809 were evaluated. Dose-limiting toxicities (DLTs), adverse events (AEs), T cell response, tumor response, and JNJ-809 bacterial shedding profile were assessed at 2 dose levels, 1 x 108 and 1 x 109 colony forming units (CFU). Results: 26 pts (median age 66.5 years, White 96%) were enrolled (1 x 108 CFU, n = 6; 1 x 109 CFU, n = 20). Median duration of treatment was 2.5 months (range 0-9.7). No DLTs occurred and 1 x 109 CFU was selected as the RP2D. Most common AEs were chills (n = 24, 92%), pyrexia (n = 21, 81%), and fatigue (n = 16, 62%). Grade ≥3 AEs were reported in 18 (69%) pts and serious AEs in 7 (27%) pts including 1 pt with investigator-assessed treatment-related grade 3 intestinal obstruction. At 1 x 108 CFU, all pts had negative blood cultures. At 1 x 109 CFU, 6 pts had LADD- Lm-positive blood cultures on day 1; blood cultures on all subsequent days were negative. JNJ-809 transiently induced peripheral cytokines including interferon-γ, interleukin-10, and tumor necrosis factor-α. Of 7 evaluable pts (1 x 109 CFU), post-treatment T cell responses were demonstrated in 6 pts to the Listeria antigen LLO and in 5 pts to ≥1 of the 4 encoded tumor antigens. Best overall response was stable disease (SD) in 13/25 evaluable pts with SD ≥16 weeks in 4 pts. The study was terminated early as the data collected from 26 pts were considered sufficient to evaluate safety and immune responses. Conclusions: JNJ-809 has a manageable safety profile consistent with that of other LADD- Lm-based therapies. Observed activation of immune responses with monotherapy did not translate into clinical activity, and further development of JNJ-809 will likely require a combination approach. Clinical trial information: NCT02625857.

An open label phase 1/2A study to evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of TRC253, an androgen receptor antagonist, in patients with metastatic castration-resistant prostate cancer

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Background: TRC253 is a high-affinity, orally active small molecule antagonist of the androgen receptor (AR) and specific mutated variants of AR that does not possess agonist activity towards either wild type or mutated AR. TRC253 inhibits AR nuclear translocation as well as AR binding to DNA and is a transcription antagonist. TRC253 treatment is efficacious in an LNCaP xenograft model driven by F877L mutant AR. Methods: In P1 dose escalation, pts with mCRPC previously treated with an AR inhibitor were assigned to increasing TRC253 doses of 40-320 mg daily. Dose escalation followed single-pt dose escalation design for the 40, 80 mg cohorts and expanded to 3+3 design in the 160, 240, 280, and 320 mg cohorts to assess safety, determine the recommended phase 2 dose (RP2D), and evaluate prostate-specific antigen response at week 12. Toxicity and efficacy assessments used NCI-CTCAE v4.03 and PCWG3 criteria, respectively. Pts were centrally screened by circulating tumor DNA using the BEAMing digital PCR assay. Results: Twenty-two pts were enrolled in phase 1 at TRC253 doses of 40 (n = 1), 80 (n = 1), 160 (n = 2), 240 (n = 6), 280 (n = 4), and 320 mg (n = 8) daily in 28-day cycles. One DLT of G3 QTcF prolongation occurred at 320 mg. No drug-related SAEs were reported. Drug-related AEs ≥ G2 included QTcF prolongation (2 G2, 2 G3), elevated lipase (1 G3), fatigue (4 G2), arthralgia (1 G2), diarrhea (1 G2), and platelet count decrease (1 G2). One pt on study had AR F877L at baseline and remained on treatment for 49 wks with PR by RECIST. The remaining 21 pts did not have AR F877L at baseline and of these, 48% (10) remained on study > 6 cycles and one pts had a > 50% decrease in PSA. Target PK exposures were achieved consistently at 280 mg. 280 mg was selected as the RP2D based on safety and PK data. Conclusions: TRC253 daily at 280 mg was well-tolerated and selected as the RP2D. P2 dose expansion is currently enrolling 2 cohorts: 15 pts with AR F877L and 30 pts without AR F877L. The objectives of P2 include collection of additional data for safety, PK, PET and efficacy of TRC253 in mCRPC pts with specific AR mutations. Clinical trial information: NCT02987829.

Abstract 3813: Development of JNJ-64164711, a low fucose anti-GITR antibody for enhanced depletion of tumor regulatory T cells (Tregs)

Background: Checkpoint blockade of PD-1/PDL-1 or CTLA-4 has demonstrated clinical benefit in a subset of cancer patients (pts). To further improve the outcome, approaches to deplete immunosuppressive Tregs are being developed. Emerging evidence supports that the TNF receptor superfamily member 18 (TNFRSF18 or GITR) is highly expressed on intratumoral (i.t.) Tregs with limited expression on effector T cells or circulating immune cells (1,2). This differential expression allows for development of monoclonal antibody (mAb) therapies that eliminate this population while sparing other immune subsets. Herein we characterize JNJ-64164711 (JNJ-711), a fully human anti-GITR mAb being developed to selectively deplete GITR+ Tregs and expand the population of pts that may respond to immunotherapy.

Methods: Treg frequency and GITR expression on human cancer specimens was performed by IHC and multicolor flow cytometric analysis (FC). JNJ-711 was assessed for binding to GITR (human and cyno) and human Fcγ receptors, and inhibition of hGITRL binding to hGITR. The JNJ-711 binding epitope was mapped by hydrogen-deuterium exchange. JNJ-711 functional activity was determined by 1) an NF-kB reporter assay, 2) antibody dependent cellular cytotoxicity (ADCC) on GITR+ cell lines, and 3) JNJ-711 mediated Treg depletion in primary pts tumor samples.

Results: GITR expression prevalence was evaluated by IHC in multiple solid tumors. Immune cell GITR expression was observed in head and neck (HN), esophageal (ESO), non-small cell lung carcinoma (NSCLC), colorectal (CRC) and prostate cancers. GITR was moderately expressed on HN and ESO tumor cells. GITR expression (by FC) was higher on tumor Tregs versus other T cell populations in the tumor and periphery across NSCLC, CRC, ovarian and renal cell carcinoma samples. GITR was differentially higher on i.t. effector Tregs (eTreg) whereas CCR4 was highest on CD4+ T cells in circulation. JNJ-711 binds to hGITR on cells with high affinity [KD= 180 pM], has a log greater affinity to FcγRIIIa [KD= 37 nM on 158V; KD= 180 nM on 158F], a slower dissociation rate than most GITR agonist (Ag) mAb tested [Koff= 5.47 x 10-4 s-1 for Fab], and binds to the CRD1 of GITR. Unlike other GITR Ag mAbs tested, JNJ-711 does not block GITR interaction with GITRL. JNJ-711 demonstrates higher ADCC mediated cell depletion than other GITR Ag mAbs in clinical development on 1) GITR+ hematologic tumor cell lines (HuT102, KMS-12-BM, RPMI 8226, JJN-3), 2) primary activated GITR+ T cells, and 3) in vitro expanded Tregs. Using dissociated primary pts samples, JNJ-711 selectively depleted i.t. eTregs.

Conclusion: JNJ-64164711 selectively depletes hGITR+ cells including Tregs and has potential to enhance antitumor immune response. This antibody is being evaluated for clinical development.

References:

1. Asma et al. Tumor Biol 2015;36:3727-34.

2. Pedroza-Gonzalez et al. OncoImmunology 2015;4:12, e1051297.

Citation Format: Cam V. Holland, John Kehoe, Judith Hailey, Rupesh Nanjunda, Eilyn Lacy, Robin Ernst, Di Zhang, Sam Wu, Alexey Teplyakov, Weimin Li, Michelle Kinder, Edward W. Thompson, Patrick Wilkinson, Jackson Wong, Gerald Chu, Linda Okonkwo, John D. Alvarez, Anhco Nguyen, Iqbal S. Grewal, Moitreyee Chatterjee-Kishore, Mark Salvati, Marco Gottardis. Development of JNJ-64164711, a low fucose anti-GITR antibody for enhanced depletion of tumor regulatory T cells (Tregs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3813.

Abstract 5040: Genomic and proteomic characterization of anti-androgen resistant cell lines

Background: Prostate cancer is the most common cancer and second most frequent cause of cancer-related deaths for men in the United States. AR-axis inhibitors have been shown to improve both progression-free survival (PFS) and overall survival (OS) in castration resistant prostate cancer (CRPC) patients however an estimated 50% of patients will go on to develop resistance to these therapies. Some mechanisms of resistance observed in the clinic include Androgen Receptor (AR) dependent events such as increased AR copy number, activating point mutations in AR, or splice variants (ARV7) both of the latter leading to constitutively active versions of AR. Alternatively, AR-independent resistance mechanisms include up-regulation of other oncogenic signaling pathways such as FGFR and PI3/Akt and induction of the nuclear hormone Glucocorticoid Receptor (GR). Finally, an increase in the emergence of a neuroendocrine phenotype is observed in the clinic with CRPC patients and is thought to be associated with chronic AR-antagonist treatment. To better understand the specific proteomic and genomic changes that occur during chronic AR inhibitor treatment we developed two enzalutamide (ENZA) resistant cell lines and performed targeted proteomic and global gene expression analysis.

Methods: We generated LnCaP and VCAP ENZA-resistant (ENZA-Res) prostate cancer cell lines. We performed gene expression analysis by using both cDNA microarray and RNA-SEQ techniques to identify novel or differential gene expression patterns between ENZA-Res and sensitive phenotypes. We also employed a targeted proteomic approach to identify changes in the relative expression levels of proteins that have historically been associated with anti-androgen resistance including, ARV7, GR and SGK-1.

Results: We have shown that ENZA-Res cell lines can undergo a significant change in morphology that is associated with an elongated neuronal-like appearance. This phenotype is associated with an induction in the mRNA expression of neuroendocrine markers, CHGA and REST along with a strong induction of GR mRNA and protein expression. We have shown that the neuroendocrine derived prostate cancer cell line, H660, also demonstrates high GR mRNA and protein content suggesting that GR may have a role in the maintenance of neuroendocrine and/ or ENZA-Res phenotypes when AR is absent. In VCaP ENZA-Res cells a significant increase in ARV7 mRNA and protein content was observed compared to parental ENZA sensitive VCaP cells. Lastly, we employed a combination of cDNA microarray and RNA-SEQ techniques to identify a molecular signature associated with anti-androgen resistance. We have identified a unique subset of genes that are differentially up-regulated in ENZA-Res cell lines compared to ENZA-sensitive cell lines. This novel molecular signature identifies several candidate genes as potential therapeutic targets that may be important in mediating anti-androgen resistance.

Citation Format: Jennifer Hertzog, Mike Russell, Michael Quigley, Marco Gottardis, Theresa McDevitt. Genomic and proteomic characterization of anti-androgen resistant cell lines. [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 5040.

Pharmacology of smac mimetics; chemotype differentiation based on physical association with caspase regulators and cellular transport

Cellular levels of inhibitor of apoptosis (IAP) proteins are elevated in multiple human cancers and their activities often play a part in promoting cancer cell survival by blocking apoptotic pathways, controlling signal transduction pathways and contributing to resistance. These proteins function through interactions of their BIR (baculoviral IAP repeat) protein domains with pathway components and these interactions are endogenously antagonized by Smac/Diablo (second mitochondrial activator of caspases/direct IAP binding protein with low isoelectric point). This report describes development of synthetic smac mimetics (SM) and compares their binding, antiproliferative and anti-tumor activities. All dimeric antagonists inhibit in vitro smac tetrapeptide binding to recombinant IAP proteins, rescue IAP-bound caspase-3 activity and show anti-proliferative activity against human A875 melanoma cells. One heterodimeric SM, SM3, binds tightly to IAP proteins in vitro and slowly dissociates (greater than two hours) from these protein complexes compared to the other antagonists. In addition, in vitro SM anti-proliferation potency is influenced by ABCB1 transporter (ATP-binding cassette, sub-family B; MDR1, P-gp) activities and one antagonist, SM5, does not appear to be an ABCB1 efflux pump substrate. All dimeric smac mimetics inhibit the growth of human melanoma A875 tumors implanted in athymic mice at well-tolerated doses. One antagonist, SM4, shows broad spectrum in vivo anti-tumor activity and modulates known pharmacodynamic markers of IAP antagonism. These data taken together demonstrate the range of diverse dimeric IAP antagonist activities and supports their potential as anticancer agents.

Discovery of BMS-641988, a Novel Androgen Receptor Antagonist for the Treatment of Prostate Cancer

BMS-641988 (23) is a novel, nonsteroidal androgen receptor antagonist designed for the treatment of prostate cancer. The compound has high binding affinity for the AR and acts as a functional antagonist in vitro. BMS-641988 is efficacious in multiple human prostate cancer xenograft models, including CWR22-BMSLD1 where it displays superior efficacy relative to bicalutamide. Based on its promising preclinical profile, BMS-641988 was selected for clinical development.

Mcl-1 antagonism is a potential therapeutic strategy in a subset of solid cancers

Cancer cell survival is frequently dependent on the elevated levels of members of the Bcl-2 family of prosurvival proteins that bind to and inactivate BH3-domain pro-apoptotic cellular proteins. Small molecules that inhibit the protein-protein interactions between prosurvival and proapoptotic Bcl-2 family members (so-called "BH3 mimetics") have a potential therapeutic value, as indicated by clinical findings obtained with ABT-263 (navitoclax), a Bcl-2/Bcl-xL antagonist, and more recently with GDC-0199/ABT-199, a more selective antagonist of Bcl-2. Here, we report study results of the functional role of the prosurvival protein Mcl-1 against a panel of solid cancer cell lines representative of different tumor types. We observed silencing of Mcl-1 expression by small interfering RNAs (siRNAs) significantly reduced viability and induced apoptosis in almost 30% of cell lines tested, including lung and breast adenocarcinoma, as well as glioblastoma derived lines. Most importantly, we provide a mechanistic basis for this sensitivity by showing antagonism of Mcl-1 function with specific BH3 peptides against isolated mitochondria induces Bak oligomerization and cytochrome c release, therefore demonstrating that mitochondria from Mcl-1-sensitive cells depend on Mcl-1 for their integrity and that antagonizing Mcl-1 function is sufficient to induce apoptosis. Thus, our results lend further support for considering Mcl-1 as a therapeutic target in a number of solid cancers and support the rationale for development of small molecule BH3-mimetics antagonists of this protein.

Influence of Extreme Long Endurance Sports Activity on Neopterin Excretion

Immune system activation has been observed during endurance exercise, but its relevance is largely unclear. We evaluated urinary neopterin excretion in an athlete competing in the Race Across America (RAAM), to determine whether neopterin excretion would indicate that immune system activation occurs during extreme endurance sport. Urinary samples were collected at the day before the race, during the whole RAAM, and, without a physical strain, seven days after the race. Neopterin normalized to creatinine concentration was determined by reversed-phase high-pressure liquid chromatography (HPLC). Data were analysed by repeated-measured analysis of variance (ANOVA). In the athlete, urinary neopterin concentration started to increase consistently after the start of the race until day four, followed by a decline thereafter, reaching values close to the starting value. The lowest average neopterin concentration was observed at day seven; this concentration was significantly lower than mean values at days 2- 6 (all p <0.05). Comparing the power output (Watt) with the neopterin concentrations at the same time point revealed a significant correlation (rs = 0.333; p <0.05). A comparison of average daily urinary neopterin excretion mean values between the test and control person showed significant differences at all time points, except for the specimen obtained at day seven. This pilot study supports the hypothesis that extreme long endurance strain at low intensities leads to an activation of the immune system. Neopterin levels could be a convenient tool to assess the immune system activation induced by training in athletes.

IGF1/insulin receptor kinase inhibition by BMS-536924 is better tolerated than alloxan-induced hypoinsulinemia and more effective than metformin in the treatment of experimental insulin-responsive breast cancer

Epidemiologic and experimental evidence suggest that a subset of breast cancer is insulin responsive, but it is unclear whether safe and effective therapies that target the insulin receptor (IR), which is homologous to oncogenes of the tyrosine kinase class, can be developed. We demonstrate that both pharmacologic inhibition of IR family tyrosine kinase activity and insulin deficiency have anti-neoplastic activity in a model of insulin-responsive breast cancer. Unexpectedly, in contrast to insulin deficiency, pharmacologic IR family inhibition does not lead to significant hyperglycemia and is well tolerated. We show that pharmacokinetic factors explain the tolerability of receptor inhibition relative to insulin deficiency, as the small molecule receptor kinase inhibitor BMS-536924 does not accumulate in muscle at levels sufficient to block insulin-stimulated glucose uptake. Metformin, which lowers insulin levels only in settings of hyperinsulinemia, had minimal activity in this normoinsulinemic model. These findings highlight the importance of tissue-specific drug accumulation as a determinant of efficacy and toxicity of tyrosine kinase inhibitors and suggest that therapeutic targeting of the IR family for cancer treatment is practical.

High-level IGF1R expression is required for leukemia-initiating cell activity in T-ALL and is supported by Notch signaling

Notch-driven expression of IGF1R promotes the growth, viability, and transplantability of T-ALL cells.

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive cancer of immature T cells that often shows aberrant activation of Notch1 and PI3K–Akt pathways. Although mutations that activate PI3K–Akt signaling have previously been identified, the relative contribution of growth factor-dependent activation is unclear. We show here that pharmacologic inhibition or genetic deletion of insulin-like growth factor 1 receptor (IGF1R) blocks the growth and viability of T-ALL cells, whereas moderate diminution of IGF1R signaling compromises leukemia-initiating cell (LIC) activity as defined by transplantability in syngeneic/congenic secondary recipients. Furthermore, IGF1R is a Notch1 target, and Notch1 signaling is required to maintain IGF1R expression at high levels in T-ALL cells. These findings suggest effects of Notch on LIC activity may be mediated in part by enhancing the responsiveness of T-ALL cells to ambient growth factors, and provide strong rationale for use of IGF1R inhibitors to improve initial response to therapy and to achieve long-term cure of patients with T-ALL.

Abstract 2300: Insulin receptor kinase inhibition is better tolerated than hypoinsulinemia and more effective than metformin in treating breast cancer

Epidemiologic and experimental evidence suggest that a subset of breast cancer is insulin-responsive, but it is unclear if safe and effective therapies that target the insulin receptor can be developed. We demonstrate that both insulin receptor family tyrosine kinase inhibition and insulin deficiency have anti-neoplastic activity in a model of insulin-responsive breast cancer in mice metabolically normal at baseline. In contrast to insulin deficiency, insulin receptor inhibition does not lead to hyperglycemia and is well-tolerated. We show that pharmacokinetic factors explain the safety of receptor inhibition relative to ligand deficiency, as BMS-536924 does not accumulate in muscle at levels sufficient to block insulin-stimulated glucose uptake. Metformin, which lowers the elevated insulin levels present in settings of insulin resistance, had minimal activity in this model. The findings highlight the importance of tissue-specific drug accumulation as a determinant of efficacy and toxicity of tyrosine kinase inhibitors, and suggest that therapeutic targeting of the insulin receptor family for cancer treatment is practical.

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 2300. doi:10.1158/1538-7445.AM2011-2300

Abstract DDT01-03: Discovery of BMS-911543, a highly selective JAK2 inhibitor, as a clinical candidate for the treatment of myeloproliferative disease and other malignancies

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

Phase I dose-escalation study of the novel antiandrogen BMS-641988 in patients with castration-resistant prostate cancer

PURPOSE

BMS-641988 is an androgen receptor antagonist with increased potency relative to bicalutamide in both in vitro and in vivo prostate cancer models. A first-in-man phase I study was conducted to define the safety and tolerability of oral BMS-641988 in patients with castration-resistant prostate cancer (CRPC).

EXPERIMENTAL DESIGN

Doses were escalated from 5 to 150 mg based on discrete pharmacokinetic parameters in cohorts of three to six subjects. After establishing safety with 20 mg of BMS-641988 in the United States, a companion study was opened in Japan to assess differences in drug metabolism between populations.

RESULTS

Sixty-one men with CRPC were treated with daily BMS-641988. The pharmacokinetics (PK) of BMS-641988 and its active metabolites were proportional to dose. One patient experienced an epileptic seizure at a dose of 60 mg administered twice. Despite achieving target drug exposures, antitumor activity was limited to one partial response. Seventeen of 23 evaluable patients (74%) exhibited stable disease on imaging (median 15 weeks; range 8-32), and 10 of 61 patients (16%) achieved a ≥ 30% decline in levels of prostate-specific antigen (PSA). Partial agonism was seen within the context of this study upon removal of the drug as evidenced by a decrease in PSA.

CONCLUSIONS

Although the clinical outcomes of predominantly stable disease and partial agonism were similar to what was observed in the preclinical evaluation of the compound, the limited antitumor activity of BMS-641988 at therapeutic dose levels coupled with an episode of seizure activity led to study closure.

Insulin receptor (IR) pathway hyperactivity in IGF-IR null cells and suppression of downstream growth signaling using the dual IGF-IR/IR inhibitor, BMS-754807

The biology of IGF-IR/IR signaling was studied in normal mouse embryonic fibroblasts (MEFs) that were either wild type (wt), heterozygous (het), or null for the IGF-IR. The ability of IGF-I, IGF-II, or insulin to stimulate serum-starved MEFs was characterized by gene expression profiling and biochemical analyses for activation of downstream signals. Each genotypic group of MEFs exhibited distinct patterns of expression both while resting and in response to stimulation. The insulin receptor (IR) pathway in IGF-IR null MEFs was hypersensitive to insulin ligand stimulation resulting in greater AKT phosphorylation than in wt or het MEFs stimulated with the same ligand. Interestingly, the IR pathway hypersensitivity in IGF-IR null MEFs occurred with no observed changes in the levels of IR isoforms A or B. A new small molecule IGF-IR inhibitor (BMS-754807), having equipotent activity against both IGF-IR and IR, proved effective in suppressing both AKT and ERK phosphorylation from both the IGF-IR and IR pathways by all three ligands tested in wt, het, and null MEFs. The use of a dual IGF-IR/IR inhibitor addresses concerns about the use of growth inhibiting therapies directed against the IGF-IR receptor in certain cancers. Lastly, comparison of the antiproliferative effects (IC(50)s) of various compounds in wt vs. null MEFs demonstrates that genetically characterized MEFs provide a simple and inexpensive tool with which to define compounds as having mostly on-target or off-target IGF-IR activities because off-target compounds affect both wt and null MEFs equally.

Abstract 5782: Androgen receptor antagonists: Lead optimization and preclinical pharmacology

The development and progression of prostate cancer is known to be dependent on androgens and their signaling mediated by the androgen receptor (AR). The primary therapeutic intervention involves using agents that lower serum testosterone (e.g., LHRH agonists), often in concert with an AR antagonist, such as bicalutamide. Despite a favorable initial anti-tumor response, most patients progress to the advanced hormone-refractory disease. The development of resistance to anti-androgen therapy has been shown to be associated with an increase in the levels of both AR mRNA and protein. This observation supports the concept that an AR antagonist with a significant improvement in potency as compared to bicalutamide and a broader spectrum of in vivo anti-tumor activity, including the bicalutamide-refractory human prostate tumor xenografts, may provide a significant clinical advantage in the treatment of advanced prostate cancer. This presentation will describe structure-activity relationships in a novel tetracyclic series of androgen receptor antagonists leading up to the identification of BMS-779333. It is a potent AR full antagonist, which exhibited broad spectrum efficacy in four human prostate tumor xenograft models. BMS-779333 did not exhibit agonist activity for AR mutant isoforms. Tumors that failed bicalutamide treatment were shown to retain their sensitivity to respond to BMS-779333. Transcriptomic changes in LuCaP-35 tumors treated with BMS-779333 were closer to castration than with other drug treatments. Based on its overall profile, BMS-779333 was selected for further preclinical evaluation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5782.

Insulin-like growth factor-1 receptor (IGF-1R) kinase inhibitors: SAR of a series of 3-[6-(4-substituted-piperazin-1-yl)-4-methyl-1H-benzimidazol-2-yl]-1H-pyridine-2-one

A series of 3-[6-(4-substituted-piperazin-1-yl)-4-methyl-1H-benzimidazol-2-yl]-1H-pyridine-2-one were synthesized to modulate CYP3A4 inhibition and improve aqueous solubility of our prototypical compound BMS-536924 (1), while maintaining potent IGF-1R inhibitory activity. Structure-activity and structure-solubility studies led to the identification of BMS-577098 (27), which demonstrates oral in vivo efficacy in animal models. The improvement was achieved by replacing morpholine with more polar bio-isoster piperazine and modulating the basicity of distal nitrogen with appropriate substitutions.

SAR of PXR transactivation in benzimidazole-based IGF-1R kinase inhibitors

The SAR of PXR transactivation by 3-(benzimidazol-2-yl)-pyridine-2-one based ATP competitive inhibitors of Insulin-like Growth Factor 1 Receptor kinase (IGF-1R) is discussed. Compounds without PXR transactivation, with in vivo antitumor activity, reduced protein binding and improved oral exposure are presented.

High IGF-IR Activity in Triple-Negative Breast Cancer Cell Lines Correlates with Sensitivity to IGF-IR Inhibitor BMS-754807 in This Subtype of Human Breast Cancer

BACKGROUND: Evidence implicates insulin-like growth factor-I (IGF-I) signaling in the development and progression of breast cancer. Within the last few years several drugs targeting IGF-I receptor (IGF-IR) have entered clinical trials and are showing promising early results. BMS-754807 is a new small molecule inhibitor of IGF-IR in Phase 1 clinical trials.METHODS: Minimal and maximal IC50 to BMS-754807 for monolayer proliferation was determined for a panel of 30 breast cancer cell lines. Comparative gene expression analysis was performed using publicly available gene expression among the most resistant and sensitive cell lines. Q-RT-PCR was used to validate gene expression differences. Using the IGF gene signature, we scored each expression profile in a panel of cell lines and tumorgrafts, for correlation with the IGF-induced patterns. IGF-IR and pY-IGF-IR levels were determined in human tumorgrafts by immunohistochemistry.RESULTS: Among the different tumor cell lines, sensitivity to BMS-754807 varied widely from 0.1µM to 25µM. When defining cell lines as sensitive or resistant based on the median IC50, there was a strong enrichment for triple negative (TN; ERa-/PR-/HER2-) breast cancer cell lines in the sensitive group (11/15), while luminal breast cancer cell lines were generally resistant (11/15). We identified 136 differentially expressed genes between sensitive and resistance cell lines. Sensitive breast cancer cell lines preferentially express genes such as CAV1, and CAV2 while resistant cell lines were associated with high expression of ErbB3, and SPDEF. As luminal breast cancer cell lines were generally resistant to BMS-754807, we examined the role of estrogen and ERa on the sensitivity to BMS-754807. ERa mRNA levels strongly correlated with resistance to BMS-754807. Consistent with this, estrogen-withdrawal sensitized luminal breast cancer cells to BMS-754807. Previously, we developed an IGF-I gene signature that was derived from breast cancer cells stimulated with IGF-I, and reported that the signature strongly correlated with the TN subtype of human breast cancer. Consistent with this observation, we found that the IGF-I signature was high in TN breast cancer cell lines, and the IGF-I signature correlated with sensitivity to BMS-754807. To examine this further, we measured IGF-IR and pY-IGF-IR levels in four recently developed tumorgraft models of TN human breast cancer and found strong reactivity in half of the models. Interestingly, the tumorgraft (MC1) with the highest IGF-IR levels and activity showed the strongest enrichment for the IGF-I gene signature.CONCLUSIONS: In summary, our data indicates that the IGF-I pathway is highly active in TN breast cancer and this study provides the preclinical rationale for targeting IGF-IR in this subtype of human breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1132.

Complete IGF Signaling Blockade by the Dual-Kinase Inhibitor, BMS-754807, Is Sufficient To Overcome Tamoxifen and Letrozole Resistance In Vitro and In Vivo

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.

Expression of insulin receptor isoform A and insulin-like growth factor-1 receptor in human acute myelogenous leukemia: effect of the dual-receptor inhibitor BMS-536924 in vitro

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 >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.

Assessing compound binding to the Eg5 motor domain using a thermal shift assay

Eg5 is a kinesin whose inhibition leads to cycle arrest during mitosis, making it a potential therapeutic target in cancers. Circular dichroism and isothermal titration calorimetry of our pyrrolotriazine-4-one series of inhibitors with Eg5 motor domain revealed enhanced binding in the presence of adenosine 5'-diphosphate (ADP). Using this information, we studied the interaction of this series with ADP-Eg5 complexes using a thermal shift assay. We measured up to a 7 degrees C increase in the thermal melting (T(m)) of Eg5 for an inhibitor that produced IC(50) values of 60 and 130 nM in microtubule-dependent adenosine triphosphatase (ATPase) and cell-based cytotoxicity assays, respectively. In general, the inhibitor potency of the pyrrolotriazine-4-one series in in vitro biological assays correlated with the magnitude of the thermal stability enhancement of ADP-Eg5. The thermal shift assay also confirmed direct binding of Eg5 inhibitors identified in a high-throughput screen and demonstrated that the thermal shift assay is applicable to a range of chemotypes and can be useful in evaluating both potent (nM) and relatively weakly binding (microM) leads. Overall, the thermal shift assay was found to be an excellent biophysical method for evaluating direct binding of a large number of compounds to Eg5, and it complemented the catalytic assay screens by providing an alternative determination of inhibitor potency.

Insulin receptor isoform A and insulin-like growth factor II as additional treatment targets in human osteosarcoma

Despite the frequent presence of an insulin-like growth factor I receptor (IGFIR)-mediated autocrine loop in osteosarcoma (OS), interfering with this target was only moderately effective in preclinical studies. Here, we considered other members of the IGF system that might be involved in the molecular pathology of OS. We found that, among 45 patients with OS, IGF-I and IGFBP-3 serum levels were significantly lower, and IGF-II serum levels significantly higher, than healthy controls. Increased IGF-II values were associated with a decreased disease-free survival. After tumor removal, both IGF-I and IGF-II levels returned to normal values. In 23 of 45 patients, we obtained tissue specimens and found that all expressed high mRNA level of IGF-II and >IGF-I. Also, isoform A of the insulin receptor (IR-A) was expressed at high level in addition to IGFIR and IR-A/IGFIR hybrids receptors (HR(A)). These receptors were also expressed in OS cell lines, and simultaneous impairment of IGFIR, IR, and Hybrid-Rs by monoclonal antibodies, siRNA, or the tyrosine kinase inhibitor BMS-536924, which blocks both IGFIR and IR, was more effective than selective anti-IGFIR strategies. Also, anti-IGF-II-siRNA treatment in low-serum conditions significantly inhibited MG-63 OS cells that have an autocrine circuit for IGF-II. In summary, IGF-II rather than IGF-I is the predominant growth factor produced by OS cells, and three different receptors (IR-A, HR(A), and IGFIR) act complementarily for an IGF-II-mediated constitutive autocrine loop, in addition to the previously shown IGFIR/IGF-I circuit. Cotargeting IGFIR and IR-A is more effective than targeting IGF-IR alone in inhibiting OS growth.

Phosphorylated insulin-like growth factor-i/insulin receptor is present in all breast cancer subtypes and is related to poor survival

Drugs that target the insulin-like growth factor-I receptor (IGF-IR) and/or insulin receptor (IR) are currently under investigation for a variety of malignancies including breast cancer. Although we have previously reported that IGF-IR expression in primary breast tumors is common, the activation status of this receptor has not been examined in relation to survival. Phosphorylated IGF-IR/IR (P-IGF-IR/IR) and its downstream signaling partner phospho-S6 (P-S6) were evaluated immunohistochemically in tumor tissue microarrays representing 438 cases of invasive breast cancer. P-IGF-IR/IR (n = 114; P = 0.046) and total levels of IR (n = 122; P = 0.009) were indicative of poor survival, whereas total IGF-IR (n = 112; P = 0.304) was not. P-IGF-IR/IR and P-S6 were coordinately expressed in primary breast tumors (likelihood ratio, 11.57; P = 6.70 x 10(-4)). Importantly, P-IGF-IR/IR was detected in all breast cancer subtypes (luminal, 48.1%; triple negative, 41.9%; and HER2, 64.3%). In vitro, the IGF-IR/IR inhibitor BMS-536924 decreased phospho-RSK and P-S6, and significantly suppressed the growth of breast cancer cell lines MCF-7, SUM149, and AU565 representing the luminal, triple negative, and HER2 subtypes, respectively, in monolayer and soft agar. BMS-536924 also inhibited growth in tamoxifen resistant MCF-7 Tam-R cells while having little effect on immortalized normal breast epithelial cells. Thus, we can determine which patients have the activated receptor and provide evidence that P-IGF-IR/IR is a prognostic factor for breast cancer. Beyond this, P-IGF-IR/IR could be a predictive marker for response to IGF-IR and/or IR-targeted therapies, as these inhibitors may be of benefit in all breast cancer subtypes including those with acquired resistance to tamoxifen.

Discovery and evaluation of 4-(2-(4-chloro-1H-pyrazol-1-yl)ethylamino)-3-(6-(1-(3-fluoropropyl)piperidin-4-yl)-4-methyl-1H-benzo[d]imidazol-2-yl)pyridin-2(1H)-one (BMS-695735), an orally efficacious inhibitor of insulin-like growth factor-1 receptor kinase with broad spectrum in vivo antitumor activity

We previously reported that 1 (BMS-536924), a benzimidazole inhibitor of the insulin-like growth factor-1 receptor, had demonstrated in vivo antitumor activity. This lead compound was found to have potent CYP3A4 inhibition, CYP3A4 induction mediated by PXR transactivation, poor aqueous solubility, and high plasma protein binding. Herein we disclose the evolution of this chemotype to address these issues. This effort led to 10 (BMS-695735), which exhibits improved ADME properties, a low risk for drug-drug interactions, and in vivo efficacy in multiple xenograft models.

Balancing oral exposure with Cyp3A4 inhibition in benzimidazole-based IGF-IR inhibitors

3-(Benzimidazol-2-yl)-pyridine-2-one-based ATP competitive inhibitors of Insulin-like Growth Factor 1 Kinase (IGF-IR) were optimized for reduced Cyp3A4 inhibition and improved oral exposure. The use of malonate as methyl anion synthon via S(N)Ar reaction and double decarboxylation under mild conditions is demonstrated.

Imidazole moiety replacements in the 3-(1H-benzo[d]imidazol-2-yl)pyridin-2(1H)-one inhibitors of insulin-like growth factor receptor-1 (IGF-1R) to improve cytochrome P450 profile

A series of 3-(1H-benzo[d]imidazol-2-yl)pyridin-2(1H)-one inhibitors of insulin-like growth factor receptor-1 (IGF-1R) were examined in which the pendant imidazole moiety was replaced to improve selectivity for IGF-1R inhibition over cytochrome P450 (CYP). Synthesis and SAR of these compounds is presented.

Discovery and initial SAR of 3-(1H-benzo[d]imidazol-2-yl)pyridin-2(1H)-ones as inhibitors of insulin-like growth factor 1-receptor (IGF-1R)

The discovery and synthesis of 3-(1H-benzo[d]imidazol-2-yl)pyridin-2(1H)-one inhibitors of insulin-like growth factor 1-receptor (IGF-1R) are presented. Installing amine containing side chains at the 4-position of pyridone ring significantly improved the enzyme potency. SAR and biological activity of these compounds is presented.

Novel 1H-(benzimidazol-2-yl)-1H-pyridin-2-one inhibitors of insulin-like growth factor I (IGF-1R) kinase

A novel class of 1H-(benzimidazol-2-yl)-1H-pyridin-2-one inhibitors of insulin-like growth factor I (IGF-1R) kinase is described. This report discusses the SAR of 4-(2-hydroxy-2-phenylethylamino)-substituted pyridones with improved IGF-1R potency.

Synthesis and SAR of pyrrolotriazine-4-one based Eg5 inhibitors

Synthesis and SAR of substituted pyrrolotriazine-4-one analogues as Eg5 inhibitors are described. Many of these analogues displayed potent inhibitory activities in the Eg5 ATPase and A2780 cell proliferation assays. In addition, pyrrolotriazine-4-one analogue 26 demonstrated in vivo efficacy in an iv P388 murine leukemia model. Both NMR and X-ray crystallographic studies revealed that these analogues bind to an allosteric site on the Eg5 protein.

Inhibitors of human mitotic kinesin Eg5: Characterization of the 4-phenyl-tetrahydroisoquinoline lead series

In a high-throughput screening effort, a series of tetrahydroisoquinolines was identified as modest inhibitors of human Eg5. A medicinal chemistry optimization effort led to the identification of R-4-(3-hydroxyphenyl)-N,N-7,8-tetramethyl-3,4-dihydroisoquinoline-2(1H)-carboxamide (32a) as a potent inhibitor of human Eg5 (ATPase IC50 104 nM) with good anti-proliferative activity in A2780 cells (IC50 234 nM).

In vitro and In vivo Antitumor Effects of the Dual Insulin-Like Growth Factor-I/Insulin Receptor Inhibitor, BMS-554417

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 >8.5 micromol/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.

Discovery of a (1H-benzoimidazol-2-yl)-1H-pyridin-2-one (BMS-536924) inhibitor of insulin-like growth factor I receptor kinase with in vivo antitumor activity

Compound 3 (BMS-536924), a novel small-molecule inhibitor of the insulin-like growth factor receptor kinase with equal potency against the insulin receptor is described. The in vitro and in vivo biological activity of this interesting compound is also reported.

Tumor development by transgenic expression of a constitutively active insulin-like growth factor I receptor

The insulin-like growth factor I receptor (IGF-IR) is a transmembrane tyrosine kinase that is essential to growth and development and also thought to provide a survival signal for the maintenance of the transformed phenotype. There has been increasing interest in further understanding the role of IGF-I signaling in cancer and in developing receptor antagonists for therapeutic application. We describe herein a novel animal model that involves transgenic expression of a fusion receptor that is constitutively activated by homodimerization. Transgenic mice that expressed the activated receptor showed aberrant development of the mammary glands and developed salivary and mammary adenocarcinomas as early as 8 weeks of age. Xenograft tumors and a cell line were derived from the transgenic animals and are sensitive to inhibition by a novel small-molecule inhibitor of the IGF-IR kinase. This new model should provide new opportunities for further understanding how aberrant IGF-IR signaling leads to tumorigenesis and for optimizing novel antagonists of the receptor kinase.

The synthesis and evaluation of [2.2.1]-bicycloazahydantoins as androgen receptor antagonists

A novel series of [2.2.1]-azahydantoins has been designed and synthesized in an enantiospecific manner. The ability of these compounds to act as antagonists to the androgen receptor was investigated and several were found to have potent activity in vitro.

Separation of retinoid X receptor homo- and heterodimerization functions

As a promiscuous dimerization partner the retinoid X receptor (RXR) can contribute to signaling by multiple nuclear receptors. However, the impact of RXR cosignaling and the possible existence of an RXR homodimer signaling pathway are largely unexplored. We report here on the separation of RXR homo- and heterodimerization as an essential step towards the elucidation of the roles of RXR homo- and heterodimers in retinoid-rexinoid signaling. RXR homodimerization was specifically disrupted by single mutations in the RXR dimerization interface. In contrast, even multiple mutations did not fully impair RXR heterodimerization with retinoic acid receptor (RAR). Importantly, the mutation of mouse RXRalpha (mRXRalpha) Tyr402 substantially weakened RAR heterodimerization while concomitantly increasing homodimerization. Not only did this lead to cooperatively enhanced RXR homodimer binding to DR1 or DR5 elements, but unexpectedly, the mutant acquired significant binding efficiency for noncognate DR3 or DR4 elements as well. The increased stability of RXR homodimers on DR1 correlated with increased transcriptional activity of mRXRalpha(Y402A) on DR1-based reporter genes. Weak, if any, heterodimerization was observed with thyroid, vitamin D(3), or peroxisome proliferator-activating receptors. A model accounting for the structural impact of the Tyr402 mutation on dimerization is discussed. These results provide the basis for a genetic replacement of wild-type RXRs by mutants like mRXRalpha(Y402A) to elucidate the physiological impact of RXR homo- and heterodimerization.

Identification of a novel transcription factor, GAGATA-binding protein, involved in androgen-mediated expression of prostate-specific antigen

Prostate-specific antigen (PSA) is the most valuable marker for the evaluation of prostate cancer progression. The expression of PSA is controlled by androgen receptor (AR) through its binding to androgen-response elements (AREs). Several AREs have been identified within the 5.8-kb PSA promoter. The main activity of this 5.8-kb PSA promoter resides in a 455-bp enhancer core region located about 4 kb upstream of the TATA box. Our study suggests that in addition to the four AREs identified in the PSA enhancer core, another regulatory element (GAGATA), which is located at the region designated PSA3.1, also contributes to transcriptional regulation by androgens. Furthermore, electrophoretic mobility shift assay revealed that a putative transcriptional factor bound the GAGATA sequence in the PSA-producing prostate cancer cell. Further studies demonstrated that GAGATA factor preferentially bound the (G/C)(A/C/T)GATA sequence. The replacement of ATA with GGG in the GAGATA sequence completely eliminated the androgen-mediated transcriptional activity of the enhancer core. By using DNA-coupled magnetic beads and the Southwestern method, a 56-60-kDa protein was identified as the putative GAGATA binding factor. EMSA and Western blotting assay suggested that AR is not involved in androgen-mediated activation through PSA3.1. Therefore, we propose that binding of the GAGATA binding factor and AR to GAGATA and AREs, respectively, of the PSA enhancer core are required for the maximum transcriptional response to androgens.

Vergleich einer standardisierten Ernährungslösung (ZPE-Glukose/Elektrolyte^®) mit einer üblichen Ernährung im Intensivbereich

<i>Ziel:</i> Vergleich einer standardisierten Ernährungslösung mit einer selbst-gemischten Infusionstherapie bei Intensivpatienten einer chirurgischen Intensivstation; Untersuchung der standardisierten Ernährungstherapie auf Praktikabilität und Effizienz. <i>Design:</i> Prospektive randomisierte Studie. <i>Rahmen:</i> Chirurgisch-traumatologische Intensivstation einer Universitätsklinik. <i>Patienten:</i> Chirurgisch-traumatologische Patienten, die länger als 6 Tage auf der Intensivstation lagen. <i>Interventionen:</i> Gabe einer standardisierten Ernährungslösung im Ein-Liter-System (ZPE-GE) bzw. Gabe einer herkömmlichen, selbstgemischten Infusionslösung (hER). Bestim-mung von Stoffwechselparametern und Serum- bzw. Harnelektrolyten, zusätzlich Bestimmung von Blut- und Harnglukose, Harnstoffproduktionsrate, Triglyzeriden. <i>Ergebnisse:</i> Die beiden Patientengruppen waren sowohl in ihren physiologischen Daten als auch in der Schwere der Erkrankung miteinander vergleichbar, Komplikationen und Unverträglichkeiten konnten unter den angegebenen Regimen nicht beobachtet werden. Die Energie- (durchschnittlich 1202 kcal/Tag in der Gruppe hER versus 1331 kcal/Tag in der Gruppe ZPE-GE) und Substratzufuhren (Glukose: 228 versus 252 g/Tag; Aminosäuren: 56 versus 64 g/Tag) sind als ausge-glichen zu betrachten, es konnten keine Stoffwechselentgleisungen beobachtet werden. Die Elektrolytzufuhr (Natrium: 56 mmol/Tag in der Gruppe hER versus 92 mmol/Tag in der Gruppe ZPE-GE; Kalium: 65 versus 68 mmol/Tag; Phosphat: 15 versus 19 mmol/Tag) scheint in der Vollperiode nicht ganz optimal zu sein. <i>Schlussfolgerungen:</i> Die standardisierte Lösung scheint gegenüber den herkömmlichen Mischungen Vorteile zu haben: Sie erleichtert das Handling im Intensiv- und Postoperativbereich und verbessert Genauigkeit, Zeitersparnis und hygienische Bedingungen beim Umgang mit diesen Lösungen. Eine Infusionsmenge von 2000 ml (300 g Glukose und 100 g Aminosäuren) dieser Lösung erscheint als ausreichend, bei höherer Zufuhr könnte die Kohlenhydrat- und Aminosäurenzufuhr zu hoch liegen. Auch bei der Elektrolytzufuhr ist eine Begrenzung auf 2000 ml (120 mmol Natrium) angezeigt. Der Natriumanteil könnte auf 50 mmol/l reduziert werden, um ein entsprechendes Natriumloading zu verhindern, bei der Phosphatzufuhr ware eine Erhöhung auf 12 mmol/l empfehlenswert. Die Lösung kann zur standardisierten parenteralen Ernährung bei einem Großteil (ca. 80%) der postoperativen und posttraumatischen Patienten herangezogen werden, nur bei Extremsituationen müssen weiterhin die Einzelkomponenten (Glukose, Aminosäuren, Fette und Elektrolyte) speziell zusammengemischt werden, um metabolische Komplikationen zu verhindern.