Juergen Mestan

AEE788: a dual family epidermal growth factor receptor/ErbB2 and vascular endothelial growth factor receptor tyrosine kinase inhibitor with antitumor and antiangiogenic activity.

Aberrant epidermal growth factor receptor (EGFR) and ErbB2 expression are associated with advanced disease and poor patient prognosis in many tumor types (breast, lung, ovarian, prostate, glioma, gastric, and squamous carcinoma of head and neck). In addition, a constitutively active EGFR type III deletion mutant has been identified in non-small cell lung cancer, glioblastomas, and breast tumors. Hence, members of the EGFR family are viewed as promising therapeutic targets in the fight against cancer. In a similar vein, vascular endothelial growth factor (VEGF) receptor kinases are also promising targets in terms of an antiangiogenic treatment strategy. AEE788, obtained by optimization of the 7H-pyrrolo[2,3-d]pyrimidine lead scaffold, is a potent combined inhibitor of both epidermal growth factor (EGF) and VEGF receptor tyrosine kinase family members on the isolated enzyme level and in cellular systems. At the enzyme level, AEE788 inhibited EGFR and VEGF receptor tyrosine kinases in the nm range (IC(50)s: EGFR 2 nm, ErbB2 6 nm, KDR 77 nm, and Flt-1 59 nm). In cells, growth factor-induced EGFR and ErbB2 phosphorylation was also efficiently inhibited (IC(50)s: 11 and 220 nm, respectively). AEE788 demonstrated antiproliferative activity against a range of EGFR and ErbB2-overexpressing cell lines (including EGFRvIII-dependent lines) and inhibited the proliferation of epidermal growth factor- and VEGF-stimulated human umbilical vein endothelial cells. These properties, combined with a favorable pharmacokinetic profile, were associated with a potent antitumor activity in a number of animal models of cancer, including tumors that overexpress EGFR and or ErbB2. Oral administration of AEE788 to tumor-bearing mice resulted in high and persistent compound levels in tumor tissue. Moreover, AEE788 efficiently inhibited growth factor-induced EGFR and ErbB2 phosphorylation in tumors for >72 h, a phenomenon correlating with the antitumor efficacy of intermittent treatment schedules. Strikingly, AEE788 also inhibited VEGF-induced angiogenesis in a murine implant model. Antiangiogenic activity was also apparent by measurement of tumor vascular permeability and interstitial leakage space using dynamic contrast enhanced magnetic resonance imaging methodology. Taken together, these data indicate that AEE788 has potential as an anticancer agent targeting deregulated tumor cell proliferation as well as angiogenic parameters. Consequently, AEE788 is currently in Phase I clinical trials in oncology.Aberrant epidermal growth factor receptor (EGFR) and ErbB2 expression are associated with advanced disease and poor patient prognosis in many tumor types (breast, lung, ovarian, prostate, glioma, gastric, and squamous carcinoma of head and neck). In addition, a constitutively active EGFR type III deletion mutant has been identified in non-small cell lung cancer, glioblastomas, and breast tumors. Hence, members of the EGFR family are viewed as promising therapeutic targets in the fight against cancer. In a similar vein, vascular endothelial growth factor (VEGF) receptor kinases are also promising targets in terms of an antiangiogenic treatment strategy. AEE788, obtained by optimization of the 7H-pyrrolo[2,3-d]pyrimidine lead scaffold, is a potent combined inhibitor of both epidermal growth factor (EGF) and VEGF receptor tyrosine kinase family members on the isolated enzyme level and in cellular systems. At the enzyme level, AEE788 inhibited EGFR and VEGF receptor tyrosine kinases in the nm range (IC50s: EGFR 2 nm, ErbB2 6 nm, KDR 77 nm, and Flt-1 59 nm). In cells, growth factor-induced EGFR and ErbB2 phosphorylation was also efficiently inhibited (IC50s: 11 and 220 nm, respectively). AEE788 demonstrated antiproliferative activity against a range of EGFR and ErbB2-overexpressing cell lines (including EGFRvIII-dependent lines) and inhibited the proliferation of epidermal growth factor- and VEGF-stimulated human umbilical vein endothelial cells. These properties, combined with a favorable pharmacokinetic profile, were associated with a potent antitumor activity in a number of animal models of cancer, including tumors that overexpress EGFR and or ErbB2. Oral administration of AEE788 to tumor-bearing mice resulted in high and persistent compound levels in tumor tissue. Moreover, AEE788 efficiently inhibited growth factor-induced EGFR and ErbB2 phosphorylation in tumors for >72 h, a phenomenon correlating with the antitumor efficacy of intermittent treatment schedules. Strikingly, AEE788 also inhibited VEGF-induced angiogenesis in a murine implant model. Antiangiogenic activity was also apparent by measurement of tumor vascular permeability and interstitial leakage space using dynamic contrast enhanced magnetic resonance imaging methodology. Taken together, these data indicate that AEE788 has potential as an anticancer agent targeting deregulated tumor cell proliferation as well as angiogenic parameters. Consequently, AEE788 is currently in Phase I clinical trials in oncology.

Abstract 4514: PQR309: A potent, brain-penetrant, dual pan-PI3K/mTOR inhibitor with excellent oral bioavailability and tolerability

The phosphatidylinositol 3-kinase (PI3K) signaling pathway is frequently activated in tumors and promotes oncogenic cell transformation, proliferation and tumor growth. PQR309, a novel dual inhibitor of PI3K and mTOR, is currently in Phase I clinical development in cancer patients. PQR309 binds potently and specifically to the ATP binding pocket of all PI3K class I isoforms and mTORC1/2, attenuates PI3K signaling and inhibits tumor cell growth. The preclinical pharmacological and toxicological characterization of PQR309 is presented here. Methods: PQR309 pharmacokinetics/-dynamics (PK/PD) were investigated in rats and mice. Tissue samples from plasma, brain and liver were analyzed by LC/MS detecting PQR309 distribution as well as blood insulin and glucose. Toxicological studies were performed in rats and dogs. Effects on neurological, hematopoietic, respiratory, lymphoid, reproductive and cardiovascular system as well as general health were monitored. The metabolic fate of PQR309 was analyzed in rat, dog and human hepatocytes. Results: PQR309 PK studies in rats, mice and dogs revealed dose-proportional PK, both PO and IV, with a half-life of 5-8 hours in plasma, brain and liver, allowing for once a day oral application. As on-target effect, increase of blood insulin and glucose could be observed within hours after oral dosage in rats, which makes both molecules suitable as PD markers. In in vivo PC-3 rat tumor xenograft models, PQR309 effectively inhibited PI3K signaling in tumors and reduced tumor growth at 10 mg/kg oral dosing. Preclinical toxicity testing showed no signs of cardiotoxicity (including lack of hERG binding), phototoxicity (3T3 NRU test) or mutagenicity (AMES test) for PQR309. No marked effect on CYP450 activity was observed making PQR309 a good combination partner in cancer therapy. As for other PI3K inhibitors, PQR309 leads at elevated doses to a fully reversible loss of body weight and appetite in rats and dogs. No further significant adverse events were observed when testing PQR309 for 28 days in these species. Conclusions: PQR309 potently inhibits class I PI3K isoforms and mTORC1/2 and shows anti-tumor effects in vitro and in vivo. The physico-chemical properties of PQR309 result in good oral bioavailability and equal distribution between plasma and brain. Pre-clinical data led to initiation of a Phase I clinical study of PQR309 in solid tumors. Citation Format: Vladimir Cmiljanovic, Robert A. Ettlin, Florent Beaufils, Walter Dieterle, Petra Hillmann, Juergen Mestan, Anna Melone, Thomas Bohnacker, Marc Lang, Natasa Cmiljanovic, Bernd Giese, Paul Hebeisen, Matthias P. Wymann, Doriano Fabbro. PQR309: A potent, brain-penetrant, dual pan-PI3K/mTOR inhibitor with excellent oral bioavailability and tolerability. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4514. doi:10.1158/1538-7445.AM2015-4514

Abstract 2664: PQR309: Structure-based design, synthesis and biological evaluation of a novel, selective, dual pan-PI3K/mTOR inhibitor

Phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) signaling is key to the control of many physiological and pathophysiological processes, and promotes cancer and inflammatory disease. Therefore, targeting of PI3K and/or mTOR pathways is currently explored in numerous clinical studies. PQR309 is a novel, brain penetrant, potent and selective pan-PI3K/mTOR inhibitor with PK properties suitable for once a day oral dosing in humans. Structure activity relationship studies for PI3K and mTOR interactions are presented, including X-Ray analysis of PI3Kgamma co-crystal structures, modeling of PI3Kalpha and mTOR structures, and chemical derivatization. This led to the identification of PQR309 as a potent pan-PI3K and moderate mTOR inhibitor. PQR309 displays excellent selectivity versus PI3K-related lipid kinases (PIKKs) and protein kinases (KINOMEscan), as well as excellent selectivity versus unrelated targets (Cerep expresSProfile). PQR309 features excellent cell permeability, and was characterized as a BCS class II compound due to its limited water solubility (40 μM). Moreover, PQR309 is not a substrate for P-glycoprotein 1 (P-gp). In A2058 melanoma cells PQR309 demonstrated inhibition of protein kinase B (PKB/Akt; pS473) and ribosomal protein S6 (S6, pSer235/236) phosphorylation with IC50 values of 0.13 μM and 0.58 μM, respectively. In IGF-stimulated MCF7 breast cancer cells, PQR309 at 1 μM inhibited phosphorylation of downstream substrates of PI3K including PKB/Akt, S6, p70S6 kinase, GSK3 and Bad by 60-95%. PQR309 inhibited proliferation of all 58 cell lines of the NCI60 panel (GI50 from 50 to 3300 nM), of the NTRC Oncoline panel (44 cell lines, GI50 from 100-6700 nM) and of a lymphoma cell line panel (40 lymphoma cell lines, GI50 from 25-1740 nM). A concise 4-step synthetic process utilizing a novel protective group strategy provides a robust and scalable supply of PQR309 for clinical trials. In summary, PQR309 is a novel, potent, dual pan-PI3K/mTOR inhibitor with a balanced PI3K vs. mTOR profile, and displays excellent physico-chemical and pharmacological properties. The safety profile of PQR309 is currently addressed in Phase I clinical studies. Citation Format: Vladimir Cmiljanovic, Natasa Cmiljanovic, Romina Marone, Florent Beaufils, Xuxiao Zhang, Marketa Zvelebil, Paul Hebeisen, Marc Lang, Juergen Mestan, Anna Melone, Thomas Bohnacker, Eugenio Gaudio, Chiara Tarantelli, Francesco Bertoni, Reto Ritschard, Vincent Pretre, Andreas Wicki, Doriano Fabbro, Petra Hillmann, Roger Williams, Bernd Giese, Matthias P. Wymann. PQR309: Structure-based design, synthesis and biological evaluation of a novel, selective, dual pan-PI3K/mTOR inhibitor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2664. doi:10.1158/1538-7445.AM2015-2664

Abstract 393A: Pharmacological characterization of the selective, orally bioavailable, potent mTORC1/2 inhibitor PQR620

Introduction: The mammalian target of rapamycin (mTOR) signaling pathway is an integrating factor in cell physiology that influences many processes like growth, metabolism and proliferation. mTOR signaling is constitutively activated in many cancers. Rapamycin is an allosteric inhibitor of mTOR that targets a subset of mTOR functions via inhibition of the mTORC1 complex. An ATP site-directed mTORC1/2 inhibitor that fully blocks all mTOR functions is desirable as cancer therapeutic. PQR620 is a novel, ATP site directed inhibitor of mTOR that is currently in pre-clinical development. PQR620 potently binds to its target (Kd = 6 nM) and shows excellent selectivity versus related and unrelated kinases [1]. Results: PQR620 inhibits mTOR signaling in stimulated MCF7 cells as detected by PathScan analysis. Excellent tolerability has been observed in mice (MTD = 150 mg/kg). A 14 day GLP toxicological study in rats showed very good tolerability (MTD = 30 mg/kg). Only minor toxicities such as dose-related changes in body weight and blood count were observed. PQR620 was administered to male C57BL/6J mice for a pharmacokinetic (PK) and pharmacodynamics (PD) evaluation. After oral application PQR620 exhibited dose-proportional PK, a maximum concentration (Cmax) in plasma and brain was reached after 30 minutes (4.8 μg/ml and 7.7 μg/ml, respectively). In muscle, Cmax (7.6 μg/ml) was reached after 2 hours. The calculated half-life (t 1/2 ) for plasma and brain was approximately 5 hours. After 8 hours, the total exposure (expressed as AUC 0-tz (area under the curve)) was 20.5 μg*h/ml in plasma, while it was approximately 30% higher in both, brain and thigh muscle (30.6 and 32.3 μg*h/ml, respectively). PQR620 potently inhibited mTOR signaling in vivo after administration of a single oral dose of 50 mg/kg. Importantly, no effect on plasma insulin levels was observed. In an OVCAR-3, ovarian carcinoma mouse xenograft, PQR620 effectively attenuated tumor growth using daily, oral dosing. Conclusion: PQR620 potently inhibits mTORC1/2 in vitro and in vivo. The physico-chemical properties of PQR620 result in good oral bioavailability and excellent brain penetration. PQR620 is well tolerated and efficiently inhibits tumor growth in xenograft models. Preclinical data allow for further development of the compound. [1] Beaufils F, Rageot D, et al., Structure-Activity Relationship Studies, Synthesis and Biological Evaluation of PQR620, a Highly Potent and Selective mTORC1/2 Inhibitor, AACR annual meeting 2016 Citation Format: Florent Beaufils, Denise Rageot, Anna Melone, Alexander Sele, Marc Lang, Juergen Mestan, Robert A. Ettlin, Petra Hillmann, Vladimir Cmiljanovic, Carolin Walter, Elisabeth Singer, Hoa HP Nguyen, Paul Hebeisen, Doriano Fabbro, Matthias P. Wymann. Pharmacological characterization of the selective, orally bioavailable, potent mTORC1/2 inhibitor PQR620. [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 393A.