Stephan Karl Zahn

BI 885578, a Novel IGF1R/INSR Tyrosine Kinase Inhibitor with Pharmacokinetic Properties That Dissociate Antitumor Efficacy and Perturbation of Glucose Homeostasis.

Inhibition of the IGF1R, INSRA, and INSRB receptor tyrosine kinases represents an attractive approach of pharmacologic intervention in cancer, owing to the roles of the IGF1R and INSRA in promoting cell proliferation and survival. However, the central role of the INSRB isoform in glucose homeostasis suggests that prolonged inhibition of this kinase could result in metabolic toxicity. We describe here the profile of the novel compound BI 885578, a potent and selective ATP-competitive IGF1R/INSR tyrosine kinase inhibitor distinguished by rapid intestinal absorption and a short in vivo half-life as a result of rapid metabolic clearance. BI 885578, administered daily per os, displayed an acceptable tolerability profile in mice at doses that significantly reduced the growth of xenografted human GEO and CL-14 colon carcinoma tumors. We found that treatment with BI 885578 is accompanied by increases in circulating glucose and insulin levels, which in turn leads to compensatory hyperphosphorylation of muscle INSRs and subsequent normalization of blood glucose within a few hours. In contrast, the normalization of IGF1R and INSR phosphorylation in GEO tumors occurs at a much slower rate. In accordance with this, BI 885578 led to a prolonged inhibition of cell proliferation and induction of apoptosis in GEO tumors. We propose that the remarkable therapeutic window observed for BI 885578 is achieved by virtue of the distinctive pharmacokinetic properties of the compound, capitalizing on the physiologic mechanisms of glucose homeostasis and differential levels of IGF1R and INSR expression in tumors and normal tissues. Mol Cancer Ther; 14(12); 2762–72. ©2015 AACR.

A comprehensive pharmacokinetic/pharmacodynamics analysis of the novel IGF1R/INSR inhibitor BI 893923 applying in vitro, in vivo and in silico modeling techniques

PurposeBI 893923 is a novel IGF1R/INSR tyrosine kinase inhibitor demonstrating anti-tumor efficacy and good tolerability. We aimed to characterize the relationship between BI 893923 plasma concentration, tumor biomarker modulation, tumor growth and hyperglycemia in mice using in silico modeling analyses.MethodsIn vitro molecular and cellular assays were used to demonstrate the potency and selectivity of BI 893923. Diverse in vitro DMPK assays were used to characterize the compound’s drug-like properties. Mice xenografted with human GEO tumors were treated with different doses of BI 893923 to demonstrate the compound’s efficacy, biomarker modulation and tolerability. PK/PD analyses were performed using nonlinear mixed-effects modeling.ResultsBI 893923 demonstrated potent and selective molecular inhibition of the IGF1R and INSR and demonstrated attractive drug-like properties (permeability, bioavailability). BI 893923 dose-dependently reduced GEO tumor growth and demonstrated good tolerability, characterized by transient hyperglycemia and normal body weight gain. A population PK/PD model was developed, which established relationships between BI 893923 pharmacokinetics, hyperglycemia, pIGF1R reduction and tumor growth.ConclusionBI 893923 demonstrates molecular properties consistent with a highly attractive inhibitor of the IGF1R/INSR. A generic PK/PD model was developed to support preclinical drug development and dose finding in mice.

Discovery of novel amino-pyrimidine inhibitors of the insulin-like growth factor 1 (IGF1R) and insulin receptor (INSR) kinases; parallel optimization of cell potency and hERG inhibition

The insulin-like growth factor-1 receptor (IGF1R) and closely related insulin receptor (INSR) are receptor tyrosine kinases which have been postulated to play a role in the tumorigenesis of certain cancers. Strategies for inhibiting oncogenic signalingvia the IGF1R and INSR include IGF1R antibodies, IGF1/2 antibodies and dual IGF1R/INSR tyrosine kinase inhibitors (TKIs). IGF1R/INSR TKIs linsitinib (OSI-906) and BMS-754807 have progressed to phase II/III clinical studies in cancer patients. We describe here our efforts to develop small molecule dual inhibitors of the IGF1R/INSR receptor kinases based on an amino-pyrimidine structural class. Our main focus was the parallel optimization of cellular potency and off target activity (principally hERG inhibition) through modulation of physicochemical properties and introduction of key structural motifs using a matched molecular pairs approach and hERG homology model.

The IGF1R/INSR Inhibitor BI 885578 Selectively Inhibits Growth of IGF2-Overexpressing Colorectal Cancer Tumors and Potentiates the Efficacy of Anti-VEGF Therapy

Clinical studies of pharmacologic agents targeting the insulin-like growth factor (IGF) pathway in unselected cancer patients have so far demonstrated modest efficacy outcomes, with objective responses being rare. As such, the identification of selection biomarkers for enrichment of potential responders represents a high priority for future trials of these agents. Several reports have described high IGF2 expression in a subset of colorectal cancers, with focal IGF2 amplification being responsible for some of these cases. We defined a novel cut-off value for IGF2 overexpression based on differential expression between colorectal tumors and normal tissue samples. Analysis of two independent colorectal cancer datasets revealed IGF2 to be overexpressed at a frequency of 13% to 22%. An in vitro screen of 34 colorectal cancer cell lines revealed IGF2 expression to significantly correlate with sensitivity to the IGF1R/INSR inhibitor BI 885578. Furthermore, autocrine IGF2 constitutively activated IGF1R and Akt phosphorylation, which was inhibited by BI 885578 treatment. BI 885578 significantly delayed the growth of IGF2-high colorectal cancer xenograft tumors in mice, while combination with a VEGF-A antibody increased efficacy and induced tumor regression. Besides colorectal cancer, IGF2 overexpression was detected in more than 10% of bladder carcinoma, hepatocellular carcinoma and non-small cell lung cancer patient samples. Meanwhile, IGF2-high non-colorectal cancer cells lines displayed constitutive IGF1R phosphorylation and were sensitive to BI 885578. Our findings suggest that IGF2 may represent an attractive patient selection biomarker for IGF pathway inhibitors and that combination with VEGF-targeting agents may further improve clinical outcomes. Mol Cancer Ther; 16(10); 2223–33. ©2017 AACR.

Abstract 1082: BI 811283, a potent inhibitor of the mitotic kinase Aurora B, shows dose- and schedule-dependent efficacy in human cancer xenograft models

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Background. The serine/threonine kinase Aurora B is involved in the regulation of several mitotic processes, including chromosome condensation, congression and segregation as well as cytokinesis. The essential functions of Aurora B and its overexpression in many cancer types render this protein kinase an attractive target for therapeutic intervention. BI 811283, a potent inhibitor of this key mitotic regulator, inhibits proliferation of a wide range of cultured human cancer cells at low nanomolar concentrations by inducing polyploidy, senescence and apoptosis. Methods. BomTac:NMRI-Foxn1nu mice were grafted subcutaneously with NCI-H460 non-small cell lung carcinoma (mutant KRAS, wild-type p53), HCT 116 colon carcinoma (mutant KRAS, wild-type p53) or BxPC-3 pancreas adenocarcinoma cells (wild-type KRAS, mutant p53). Treatment was initiated when the tumors had reached a volume of ∼50 mm3. BI 811283 was injected intravenously once or twice weekly as a single bolus or b.i.d. Alternatively, the compound was administered once-weekly by a continuous 24 h infusion via subcutaneously implanted osmotic mini-pumps. Multiple dose levels and dosing schedules were evaluated. Results. In models of human non-small cell lung cancer, colon carcinoma and pancreas carcinoma, multiple cycles of treatment with BI 811283 at total weekly doses of 20 to 75 mg/kg resulted in dose-dependent inhibition of tumor growth or tumor regression. Continuous s.c. infusion at 20 mg/kg over 24 h once-weekly was clearly superior to all bolus injection schedules delivering weekly doses up to 75 mg/kg. Furthermore, regression of large tumors (350 mm3) was induced in the HCT 116 colon carcinoma model. Biomarker analyses of HCT 116 tumors revealed that therapeutic doses of BI 811283 inhibited phosphorylation of histone H3, a direct substrate of Aurora B. Histological examination showed an accumulation of enlarged, multinucleated cells in accordance with the expected mechanism of action. Conclusions. BI 811283 has demonstrated potent antitumor activity in multiple cancer models at well-tolerated doses; treated tumors show hallmarks of Aurora B inhibition. Continuous infusion over 24 h provides a superior therapeutic index compared with bolus administration. The compound is currently under investigation in Phase I clinical trials. 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 1082.

Abstract 1080: Molecular and cellular pharmacology of BI 811283, a potent inhibitor of Aurora B kinase

Background. The serine/threonine kinase Aurora B is involved in the regulation of several mitotic processes, including chromosome condensation, congression and segregation as well as cytokinesis. These essential functions of Aurora B and its overexpression in many cancer types render this protein kinase an attractive target for anticancer drug development. Methods. BI 811283 was profiled in enzymatic kinase assays as well as in proliferation assays on various human cancer cell lines. Cell cycle status was assessed by DNA content analysis (Cellomics ArrayScan, FACScalibur). Histone H3 phosphorylation was determined by immunofluorescence (Cellomics ArrayScan). Apoptosis was detected by Western blotting for cleaved PARP and microscopic enumeration of DAPI-stained cells showing nuclear fragmentation. Senescent cells were identified by staining for SA-s-Gal activity. Results. BI 811283 inhibited human Aurora B kinase activity with an IC 50 value of 9 nM, Aurora A and C kinases with 70 nM and 17 nM, respectively. In a panel of 46 additional kinases representative of the human kinome, BI 811283 at 1000 nM inhibited 7/46 kinases by more than 50%. EC 50 values for inhibition of proliferation of >20 human cancer cell lines were in the range of 2 to 14 nM. In the non-small cell lung cancer cell line NCI-H460, treatment with BI 811283 resulted in a rapid ( 80%, paralleled by a marked increase in cell volume. An increase of cleaved poly (ADP-ribose) polymerase and a concomitant increase in the fraction of cells with nuclear fragmentation from Conclusions. BI 811283 is a potent and selective Aurora kinase inhibitor that inhibits proliferation of cancer cells independent of tissue origin or oncogenome status. Treated cells exhibit a polyploid phenotype characteristic for Aurora B inhibition and show hallmarks of senescence as well as a slow onset of apoptosis in a small fraction of cells. In vivo activity of BI 811283 has been demonstrated in multiple cancer xenograft models in nude mice (see accompanying poster). Phase I clinical trials are ongoing. 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 1080.

Pharmacological Profile of BI 847325, an Orally Bioavailable, ATP-Competitive Inhibitor of MEK and Aurora Kinases.

Although the MAPK pathway is frequently deregulated in cancer, inhibitors targeting RAF or MEK have so far shown clinical activity only in BRAF- and NRAS-mutant melanoma. Improvements in efficacy may be possible by combining inhibition of mitogenic signal transduction with inhibition of cell-cycle progression. We have studied the preclinical pharmacology of BI 847325, an ATP-competitive dual inhibitor of MEK and Aurora kinases. Potent inhibition of MEK1/2 and Aurora A/B kinases by BI 847325 was demonstrated in enzymatic and cellular assays. Equipotent effects were observed in BRAF-mutant cells, whereas in KRAS-mutant cells, MEK inhibition required higher concentrations than Aurora kinase inhibition. Daily oral administration of BI 847325 at 10 mg/kg showed efficacy in both BRAF- and KRAS-mutant xenograft models. Biomarker analysis suggested that this effect was primarily due to inhibition of MEK in BRAF-mutant models but of Aurora kinase in KRAS-mutant models. Inhibition of both MEK and Aurora kinase in KRAS-mutant tumors was observed when BI 847325 was administered once weekly at 70 mg/kg. Our studies indicate that BI 847325 is effective in in vitro and in vivo models of cancers with BRAF and KRAS mutation. These preclinical data are discussed in the light of the results of a recently completed clinical phase I trial assessing safety, tolerability, pharmacokinetics, and efficacy of BI 847325 in patients with cancer. Mol Cancer Ther; 15(10); 2388–98. ©2016 AACR.

Abstract 1919: Pharmacological characterization of BI 847325, a dual inhibitor of MEK and Aurora kinases

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL The RAS-dependent MAP kinase signaling pathway plays an important role in the regulation of cell proliferation and survival. RAS genes are frequently mutated in human cancer; however, it has not been possible to date to design direct inhibitors of RAS proteins. Inhibitors of the downstream kinase MEK are active against a subset of KRAS-mutant cancers in preclinical studies, but have shown limited success to date in clinical trials. We have identified a compound that potently inhibits MEK as well as Aurora kinases, a family of serine/threonine kinases involved in the regulation of mitosis. In enzymatic assays, BI 847325 inhibited the activity of Aurora A, B and C with IC50 values of 3, 25 and 15 nM, respectively; IC50 values of 25 and 4 nM were determined for MEK1 and MEK2, respectively. To determine whether the enzyme profile translates into cellular activity we used Western blot and FACE-ELISA assays of phospho-histone H3 (pHH3) and phospho-ERK (pERK) levels in cells treated with BI 847325 and observed EC50 values of 44 nM (NCI-H460 cells, KRAS and PI3Kα mutant) and 37 nM (A375 cells, BRAF mutant), respectively. In vitro profiling in a panel of 240 cell lines with diverse tissue origin and genetic background demonstrated that BI 847325 is a potent inhibitor of cell proliferation (gm GI50 = 28 nM) and induces cell death in a subset of cell lines. In vitro potency significantly correlated with mutations in RAS or BRAF. For comparison, a significant correlation of mutation status and sensitivity was also observed for a selective MEK inhibitor, AZD6244, but not for a selective Aurora inhibitor, BI 811283. In vivo efficacy was studied in nude mouse xenograft models of NSCLC (Calu-6, mutant KRAS) and cutaneous melanoma (A375, mutant BRAF). A daily oral dose of 10 mg/kg resulted in complete inhibition of tumor growth in the Calu-6 model (TGI = 102%, regression in 4/7 animals) and the A375 model (TGI = 116%, regression in 7/7 animals). Inhibition of Aurora B and MEK was monitored ex vivo by determining the phosphorylation state of histone H3 and ERK1/2 in tumor tissue. Immunohistochemical analyses confirmed a significant reduction of both pERK and pHH3 levels in the A375 tumors of treated animals compared to controls. To further profile the mode of action of the compound, the efficacy of BI 847325 in the MIAPaCa2-pancreatic adenocarcinoma model (mutant KRAS) was directly compared with that of the MEK inhibitor GSK 1120212. BI 847325 effectively induced tumor regression (TGI on day 22 = 126%) that was maintained in all animals on day 43. In contrast, treatment with GSK 112021 resulted in initial tumor regression, followed by re-growth after 3-4 weeks (TGI on day 22 = 129%; regrowth on day 43 in 5/7 animals). Inhibition of Aurora kinase in addition to MEK blockade thus may prevent/delay onset of resistance. Additional xenograft models with diverse genetic background are currently under investigation. Clinical development of BI 847325 has been initiated. 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 1919. doi:1538-7445.AM2012-1919