Annette O. Walter

In vitro and In vivo Characterization of Irreversible Mutant-Selective EGFR Inhibitors that are Wild-type Sparing

Patients with non–small cell lung carcinoma (NSCLC) with activating mutations in epidermal growth factor receptor (EGFR) initially respond well to the EGFR inhibitors erlotinib and gefitinib. However, all patients relapse because of the emergence of drug-resistant mutations, with T790M mutations accounting for approximately 60% of all resistance. Second-generation irreversible EGFR inhibitors are effective against T790M mutations in vitro, but retain affinity for wild-type EGFR (EGFRWT). These inhibitors have not provided compelling clinical benefit in T790M-positive patients, apparently because of dose-limiting toxicities associated with inhibition of EGFRWT. Thus, there is an urgent clinical need for therapeutics that overcome T790M drug resistance while sparing EGFRWT. Here, we describe a lead optimization program that led to the discovery of four potent irreversible 2,4-diaminopyrimidine compounds that are EGFR mutant (EGFRmut) selective and have been designed to have low affinity for EGFRWT. Pharmacokinetic and pharmacodynamic studies in H1975 tumor–bearing mice showed that exposure was dose proportional resulting in dose-dependent EGFR modulation. Importantly, evaluation of normal lung tissue from the same animals showed no inhibition of EGFRWT. Of all the compounds tested, compound 3 displayed the best efficacy in EGFRL858R/T790M-driven tumors. Compound 3, now renamed CO-1686, is currently in a phase I/II clinical trial in patients with EGFRmut-advanced NSCLC that have received prior EGFR-directed therapy. Mol Cancer Ther; 13(6); 1468–79. ©2014 AACR.

Abstract DDT02-02: BAY 1143572: A first-in-class, highly selective, potent and orally available inhibitor of PTEFb/CDK9 currently in Phase I, inhibits MYC and shows convincing anti-tumor activity in multiple xenograft models by the induction of apoptosis

PTEFb/CDK9 mediated transcription of short-lived anti-apoptotic survival proteins like MYC, a key oncogene in multiple tumors, plays a critical role in cancer cell growth and survival. In addition, these survival proteins exhibit important functions in the development of resistance to chemotherapy. In contrast to pan-CDK inhibitors which are currently evaluated in Phase I and II clinical trials, to our knowledge PTEFb selective inhibitors have not been explored for clinical utility. We report for the first time the preclinical profile and structure of BAY 1143572, a novel selective PTEFb/CDK9 inhibitor currently being investigated in a Phase I clinical trial. BAY 1143572 had potent and highly selective PTEFb-kinase inhibitory activity in the low nanomolar range against PTEFb/CDK9 and an at least 50-fold selectivity against other CDKs in enzymatic assays. Furthermore, BAY 1143572 showed a favorable selectivity against a panel of non-CDK kinases in vitro. The potent enzymatic activity on PTEFb translated into broad antiproliferative activity against a panel of tumor cell lines with sub-micromolar IC-50 values. In line with the proposed mode of action, a concentration-dependent inhibition of the phosphorylation of the RNA polymerase II and downstream reduction of MYC mRNA and protein levels was observed in vitro. This inhibition was accompanied by an induction of apoptosis in cellular assays. BAY 1143572 also showed single agent in vivo efficacy at tolerated doses in various xenograft tumor models in mice and rats upon once daily oral administration. Potent anti-tumor activity characterized with partial or even complete remissions could be documented in models showing different MYC gene alterations like amplifications and translocations. Treatment with BAY 1143572 resulted in a transient inhibition of intratumoral MYC mRNA and protein levels and an induction of apoptosis in these models. The inhibition of MYC mRNA was also observed in blood cells of BAY 1143572-treated rats indicating the potential clinical utility of MYC in blood cells as a pharmacodynamic marker in clinical development. The in vivo efficacy of BAY 1143572 was significantly enhanced in combination with several chemotherapeutics in different solid tumor models. These pharmacology data provided the rationale for the initiation of clinical development of BAY 1143572 in advanced cancer patients (NCT01938638). In conclusion, our data provide preclinical proof of concept for BAY 1143572 as a potent and highly selective inhibitor of PTEFb/CDK9 with first-in-class potential. Further clinical evaluation of BAY 1143572 for the treatment of cancers dependent on the transcription of the key oncogene MYC and other short-lived survival proteins is warranted. Citation Format: Arne Scholz, Ulrich Luecking, Gerhard Siemeister, Philip Lienau, Ulf Boemer, Peter Ellinghaus, Annette O. Walter, Ray Valencia, Stuart Ince, Franz von Nussbaum, Dominik Mumberg, Michael Brands, Karl Ziegelbauer. BAY 1143572: A first-in-class, highly selective, potent and orally available inhibitor of PTEFb/CDK9 currently in Phase I, inhibits MYC and shows convincing anti-tumor activity in multiple xenograft models by the induction of apoptosis. [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 DDT02-02. doi:10.1158/1538-7445.AM2015-DDT02-02

Abstract 2101A: CNX-2006, a novel irreversible epidermal growth factor receptor (EGFR) inhibitor, selectively inhibits EGFR T790M and fails to induce T790M-mediated resistance in vitro.

Introduction: EGFR mutant lung cancers are highly sensitive to first generation EGFR tyrosine kinase inhibitors (TKIs; gefitinib and erlotinib), but resistance eventually develops. In the majority of patients, such acquired resistance (AR) is mediated by a second-site T790M “gatekeeper” mutation. Second generation TKIs (e.g. afatinib, dacomitinib, neratinib) are more potent but have minimal efficacy as single agents in patients with AR. Notably, second generation TKIs still inhibit the wild type receptor which limits dose escalation, and similar to gefitinib/erlotinib, they still select for T790M-mediated resistance in vitro due to selectivity for drug-sensitive mutations (exon 19 deletions and L858R) compared to T790M. In this study, we characterize the inhibitory properties of CNX-2006, a novel irreversible EGFR TKI developed to inhibit specifically T790M. CNX-2006 is the prototype for CO-1686 which is currently in phase I clinical trials for the treatment of EGFR-mutant lung cancer. Methods and Results: CNX-2006 potency was assessed via multiple methods: i) surrogate kinase assays using immunoblotting of lysates from 293 cells transfected with cDNAs encoding various EGFR mutations and treated with drug, ii) growth inhibition assays using various erlotinib-resistant EGFR mutant cell lines or engineered Ba/F3 cells, and iii) H1975 xenografts expressing EGFR(L858R/T790M). CNX-2006 exhibited specificity and potent in vitro and in vivo activity against T790M. The drug also showed activity against uncommon EGFR mutations including G719S, L861Q, an exon 19 insertion mutant (I744-K745insKIPVAI), and T854A, but not an exon 20 insertion (H773-V774HVdup). In an in vitro resistance model, CNX-2006 significantly inhibited the emergence of resistant cells compared with erlotinib (1/24 vs 11/24, p = 0.0013). Chronic exposure to escalating doses of CNX-2006 failed to select for and/or enhance T790M-mediated resistance using PC-9 or HCC827 cells (both harboring exon 19 deletions), or PC-9/ER and HCC827/ER cells with existing T790M and resistance to erlotinib. In PC-9 and HCC827 cells with acquired resistance to CNX-2006, MET amplification or other known mutations in the RAS/MEK/ERK signaling pathway have not been detected. Conclusions: These results demonstrate that the profile of CNX-2006 is different from first and second generation EGFR TKIs. CNX-2006 selectively targets T790M, shows activity against other common and uncommon EGFR mutations, and does not select for resistance mediated by T790M. Additional studies are ongoing to elucidate mechanisms of acquired resistance to CNX-2006. Citation Format: Kadoaki Ohashi, Kenichi Suda, Jing Sun, Yumei Pan, Annette O. Walter, Alex Dubrovskiy, Robert Tjin, Tetsuya Mitsudomi, William Pao. CNX-2006, a novel irreversible epidermal growth factor receptor (EGFR) inhibitor, selectively inhibits EGFR T790M and fails to induce T790M-mediated resistance in vitro. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2101A. doi:10.1158/1538-7445.AM2013-2101A

Abstract 3022: BAY 1143572, a first-in-class, highly selective, potent and orally available inhibitor of PTEFb/CDK9 currently in Phase I, shows convincing anti-tumor activity in preclinical models of acute myeloid leukemia (AML)

PTEFb/CDK9 mediated transcription of short-lived anti-apoptotic survival proteins like Mcl-1 and Myc, plays a critical role in cancer cell growth and survival in various tumor entities including AML. In addition, these survival proteins exhibit important functions in the development of resistance to chemotherapy. In contrast to pan-CDK inhibitors, to our knowledge PTEFb selective inhibitors have not been explored for clinical utility. We report the preclinical activity of BAY 1143572, a novel selective PTEFb/CDK9 inhibitor (AACR; Cancer Res 2015;75(15 Suppl):Abstract nr DDT02-02) currently being investigated in Phase I clinical trials in advanced cancer (NCT01938638) and acute leukemia (NCT02345382) in various in vitro, ex vivo and in vivo models of AML. BAY 1143572 inhibited the proliferation of 7 MLL-rearrangements positive and negative AML cell lines with a median IC50 of 385 nM (range 230-1100 nM) and induced apoptosis. Furthermore, BAY 1143572 showed potent in vitro activity in 8 out of 10 non-MLL-rearranged patient derived AML samples incl. NPM1 mutant and Flt3-ITD positive samples derived from intermediate and high risk patients. Moreover, we elucidated the dynamic changes of the cellular proteome/phosphoproteome upon pharmacological and genetic PTEFb inhibition and identified PTEFb interaction partners in various AML in vitro models. These analyses uncover the oncogenic PTEFb-dependent signaling networks and substantiate the molecular rationale for the use of PTEFb inhibitors in this indication. When applied in vivo, BAY 1143572 exhibited single agent efficacy at tolerated doses in 4 out of 5 AML xenograft tumor models in mice and in 2 out of 2 AML xenograft tumor models in rats upon once daily oral administration. Of note, partial or even complete remissions could be achieved in several models. Furthermore, intermittent dosing schedules with up to 4 days treatment pauses were feasible in terms of efficacy and tolerability. Using MOLM-13 xenografts in mice and rats to address the in vivo MoA of BAY 1143572, a transient inhibition of RNA polymerase II phosphorylation, MYC mRNA and protein levels, MCL-1 mRNA and protein levels, and an induction of apoptosis was documented. In conclusion, our data provide the rationale for the initiation of clinical development of BAY 1143572 as a potent and highly selective inhibitor of PTEFb/CDK9 with first-in-class potential for the treatment of AML patients. A phase I clinical trial to determine the safety, tolerability and recommended Phase 2 dose in this indication is ongoing (NCT02345382). Citation Format: Arne Scholz, Thomas Oellerich, Akhtar Hussain, Sarah Lindner, Ulrich Luecking, Annette O. Walter, Peter Ellinghaus, Ray Valencia, Franz von Nussbaum, Dominik Mumberg, Michael Brands, Stuart Ince, Hubert Serve, Karl Ziegelbauer. BAY 1143572, a first-in-class, highly selective, potent and orally available inhibitor of PTEFb/CDK9 currently in Phase I, shows convincing anti-tumor activity in preclinical models of acute myeloid leukemia (AML). [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 3022.

Abstract 3524: BAY 1238097, a novel BET inhibitor with strong efficacy in hematological tumor models

Several BET inhibitors with strong anti-tumor efficacy have been described in the last few years. Most of them are derived from diazepine and azepine scaffolds, but more recently quinazolinones and isoxazoles chemotypes have also been described. We have identified a novel scaffold with strong BET inhibitory activity. Here we describe the biochemical characteristics of BAY 1238097 and its anti-proliferative activity in acute myeloid leukemia (AML) and multiple myeloma (MM) models. In vitro, BAY 1238097 showed strong inhibitory activity (IC50 In vivo, BAY 1238097 showed strong efficacy in the AML models THP-1, MOLM-13 and KG-1, with T/C between 13 and 20%. Overall, the compound was well tolerated at MTD, with body weight losses of 5-9% at nadir. BAY 1238097 was also active in MM models. Efficacy was observed against a human IGH-cyclin D1 translocated MOLP-8 model with a T/C of 3%, whereas the standard-of-care agents bortezomib and lenalidomide were inactive or poorly active. In this model, BAY 1238097 was well tolerated at 10 mg/kg applied over 14 days, with no body weight loss measured. BAY 1238097 was also active against the FGFR/MMSET translocated model NCIH929, with 19% T/C versus 49% T/C for the standard-of-care lenalidomide. The compound was well tolerated applied at 12 mg/kg for 9 days (maximum body weight loss 6%). Gene expression profiling performed in liver, blood and duodenum of rats treated daily with 2 mg/kg BAY 1238097 for 14 days demonstrated substantial effects on genes involved in cell proliferation and in the immune response in vivo. Altogether, BAY 1238097 is a potent inhibitor of BET binding to histones and has strong anti-proliferative activity in different AML and MM models through down-regulation of c-Myc levels and its downstream transcriptome. Initiation of clinical studies with BAY 1238097 is planned for early 2015. Citation Format: Pascale Lejeune, Tatsuo Sugawara, Kathy A. Gelato, Heidrun Ellinger-Ziegelbauer, Amaury E. Fernandez-Montalvan, Norbert Schmees, Stephan Siegel, Hilmar Weinmann, Volker Gekeler, Annette O. Walter, Matthias Ocker, Stuart Ince, Bernard Haendler. BAY 1238097, a novel BET inhibitor with strong efficacy in hematological tumor models. [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 3524. doi:10.1158/1538-7445.AM2015-3524

Abstract CT209: A phase I study with the oral pan-CDK inhibitor BAY 1000394 in patients with advanced stage small cell lung or ovarian cancer

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Background: BAY 1000394 (BAY) is an oral pan-CDK inhibitor targeting CDKs 1, 2, 4, 7 and 9 in the low nanomolar range. The recommended phase 2 dose was identified in the previously reported dose escalation part of this multicenter phase I study. We report here additional data on pharmacodynamics (PD) biomarker and clinical outcome of patients with advanced SCLC and ovarian cancer (OC). Methods: BAY was orally administered as monotherapy on a 3-days on/4-days off schedule at 5 mg bid in continuous 21 day cycles. A novel PCR-based PD assay using whole blood obtained on days 1 and 10 of the first treatment cycle was performed. Response rate was assessed every second cycle using RECIST 1.1. Results: A total of 25 pre-treated patients with extensive stage SCLC and 25 patients with advanced OC (stage IIIB/IV) were enrolled to this study. In addition, 6 patients with distinct genetic profiles (e.g. cyclin E amplification) related to the mode of action of BAY were included at Gustave Roussy, Paris, France. The overall disease control rate (DCR, includes stable disease or better) according to RECIST was 32.3% in the total study population with 20 SD. On average, patients with SD or better stayed on treatment for 103.5 days (4.9 cycles). DCRs were 29% (n=9) for SCLC, 36% for ovarian cancer (n=9) and 33.3% for patients harboring tumor specific mutations (n=2), respectively. Levels of Proliferating Cell Nuclear Antigen (PCNA) were analyzed in the blood as surrogate biomarker and reduction of PCNA expression was detected at the recommended phase 2 dose of 5 mg bid. Nausea and diarrhea (CTCAE grades 1 and 2) were commonly observed but proved to be clinically manageable with standard medication. While the dose escalation trial confirmed MTD at 7.5 mg bid, the occurrence of four thromboembolic events at this dose level led to the reduction of the recommended phase 2 dose to 5 mg bid. No additional drug related thromboses were observed at the lower dose and the overall incidence rate (7.9%) of thromboembolic events at 5 mg bid is below the expected rate in this patient population. Conclusion: The continuous oral treatment with the pan-CDK inhibitor BAY 1000394 is feasible and showed signs of efficacy and pharmacodynamic activity at 5 mg bid on a 3-days on/4-days off treatment schedule in a non-biomarker selected expansion population of phase I patients with advanced stage SCLC or ovarian cancer. Citation Format: Rastilav Bahleda, Fabrice Barlesi, Christine Audebert, Maurice Perol, Isabelle Ray-Coquard, Dirk Strumberg, Beate Schultheis, Ramaswamy Govindan, Grace K. Dy, Gerard Zalcman, Annette O. Walter, Martin Kornacker, Matthias Ocker, Jean-Charles Soria. A phase I study with the oral pan-CDK inhibitor BAY 1000394 in patients with advanced stage small cell lung or ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT209. doi:10.1158/1538-7445.AM2014-CT209

Abstract 3244: Role of epithelial-mesenchymal transition (EMT) in sensitivity to CNX-2006, a novel mutant-selective EGFR inhibitor which overcomes in vitro T790M-mediated resistance in NSCLC.

Background: EGFR is an established target in advanced NSCLC, and the EGFR tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib have been approved for the treatment of patients harbouring activating-EGFR mutations. Unfortunately, their efficacy is limited by acquired resistance, caused in ≈50% of the cases by the T790M secondary point-mutation. Several EGFR inhibitors have been developed with the aim to overcome such resistance. However, emergence of in vitro resistance due to T790M amplification has been reported for second-generation EGFR-TKIs. Therefore we evaluated the efficacy of CNX-2006, a prototype of the novel mutant-selective EGFR-TKI CO-1686, which is currently in a phase I clinical trial in previously treated mutant EGFR NSCLCs. Methods: CNX-2006 was provided by Celgene Avilomics Research. Its antiproliferative activity was tested by sulforhodamine B assay in 12 NSCLC cell lines, previously characterized for EGFR and K-Ras mutational status and gefitinib sensitivity, including PC9GR4 and PC9DR1 (kindly provided by Dr. Janne, Harvard University, Boston, USA). Novel CNX-2006 resistant clones have been established starting from the EGFR T790M cells H1975 and PC9GR4, and several markers have been characterized by RT-PCR, kinase array and Western blot. Results: CNX-2006 inhibited cell proliferation independently from K-Ras mutations while it was as effective as gefitinib in activating-EGFR mutation positive cells. In the cell lines expressing wild-type EGFR CNX-2006 and gefitinib had limited anti-proliferative activity. CNX-2006 inhibited EGFR-T790M cells growth up to 1000-fold more compared to wild-type EGFR cells. EGFR inhibition was observed in cells harbouring the T790M mutation at IC50 values below 20 nM after 1 hour exposure to the drug. In contrast to gefitinib, CNX-2006 also significantly reduced the volume of tumor spheres derived from H1975 cells. Multiple CNX-2006 resistant clones were generated by exposing H1975 or PC9GR4 cells to increasing drug concentrations, leading to 30-fold resistant clones, which grow in CNX-2006 concentrations 16-20 times the initial IC50s. This resistance was retained for at least 3 months after drug removal. CNX-2006 resistant clones showed differences in expression of several biomarkers associated with EMT, such as a 3-fold reduction of E-cadherin mRNA and a 60-fold increase in MMP9 compared to the parental cells. Conclusions: CNX-2006 is a potent, mutant-selective EGFR inhibitor with excellent in vitro activity in cells with activating EGFR mutations, as well as in cells harbouring the T790M mutation. Future studies in mechanisms underlying EMT are warranted and might be used to prevent CNX-2006 resistance. Citation Format: Elena Galvani, Elisa Giovannetti, Annette O. Walter, Robert Tjin, Henk Dekker, Pier Giorgio Petronini, Egbert F. Smit, Godefridus J. Peters. Role of epithelial-mesenchymal transition (EMT) in sensitivity to CNX-2006, a novel mutant-selective EGFR inhibitor which overcomes in vitro T790M-mediated resistance in NSCLC. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3244. doi:10.1158/1538-7445.AM2013-3244

Abstract A095: Phase Ib study of anetumab ravtansine in combination with pemetrexed and cisplatin in patients with mesothelin-expressing epithelial mesothelioma or nonsquamous non-small cell lung cancer

Background: Phase I study with the antibody-drug conjugate anetumab ravtansine demonstrated promising safety and efficacy as monotherapy in mesothelin-expressing tumors, and in particular for patients with advanced metastatic malignant pleural mesothelioma. Pemetrexed in combination with cisplatin is standard for first-line treatment of patients with metastatic mesothelioma and NSCLC. We therefore conducted a phase Ib study to determine the safety, tolerability, and maximum tolerated dose (MTD) of anetumab ravtansine in combination with pemetrexed/cisplatin (Pem/Cis) in subjects with mesothelin-expressing predominantly epithelial mesothelioma or nonsquamous NSCLC. Methods: Patients with histologically confirmed, unresectable, locally advanced or metastatic, mesothelin-expressing predominantly epithelial pleural or peritoneal mesothelioma or nonsquamous NSCLC, who previously failed ≤3 prior lines of chemotherapy, were eligible. Patients were prescreened based on obligatory tumor staining for mesothelin as determined by the Ventana MSLN (SP74) immunohistochemistry assay. Anetumab ravtansine was administered by 1-hour IV infusion on day 1 of every 21-day treatment cycle (Q3W). Pem (500 mg/m2) and Cis (75 mg/m2) were administered as IV infusions Q3W. Serial plasma samples were collected and analyzed for anetumab ravtansine and its components, pemetrexed, total and free platinum. Response to therapy was assessed by RECIST 1.1 and modified RECIST criteria for mesothelioma. Results: As of June 12, 2017, 17 patients had been treated and had received ≥2 cycles of treatment, including 7 patients with pleural mesothelioma, 9 with peritoneal mesothelioma, and 1 with NSCLC. Three patients were treated with anetumab ravtansine 5.5 mg/kg in combination with Pem/Cis with no dose-limiting toxicity (DLT). Six patients were then treated with anetumab ravtansine 6.5 mg/kg in combination with Pem/Cis, again without DLTs. This dose in combination was deemed as the MTD. An additional 8 patients were enrolled in an MTD expansion cohort. Anetumab ravtansine-related adverse events were mainly grade (G)1 and G2. G1/G2 eye toxicities were possibly more frequent with the combination than in historical data. There was one G3 corneal microcystic event and one G3 hypertension. There was a 50% overall response rate (all partial responses) from 16 evaluable patients. Of 13 patients treated at the 6.5 mg/kg MTD dose of anetumab ravtansine in combination with Pem/Cis, the overall response rate was 46%. Based on comparisons to historical data and within-subject comparisons in small number of subjects, clinically relevant PK interaction was not observed. Conclusions: Anetumab ravtansine at 6.5 mg/kg dosed Q3W in combination with standard dosing of Pem/Cis had a manageable toxicity profile without evidence of PK interaction and with early signs of clinical efficacy. Anetumab ravtansine at 6.5 mg/kg in combination with Pem 500 mg/m2 and Cis 75 mg/m2, all administered in a Q3W regimen, is thus feasible and the recommended dose for future study. Citation Format: Raffit Hassan, Ding Wang, John Wrangle, Anish Thomas, Angus Byars, Lianne Asschert, Rolando Atienza, Prabhu Rajagopalan, Annette Walter, Jun Zhang, Nenad Sarapa, Hedy Kindler. Phase Ib study of anetumab ravtansine in combination with pemetrexed and cisplatin in patients with mesothelin-expressing epithelial mesothelioma or nonsquamous non-small cell lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A095.

Abstract 4714: In vivo efficacy of BET inhibitor BAY 1238097 in preclinical models of melanoma and lung cancer

Bromodomain and extra terminal domain (BET) family proteins which bind to acetylated lysines of histones and regulate gene transcription are promising targets in oncology. We have previously shown that the BET inhibitor BAY 1238097 possesses strong activity in a number of hematological models, both in vitro and in vivo (AACR 2015). Here we show that BAY 1238097 is also able to inhibit the growth of solid tumors such as melanoma and lung tumors. BAY 1238097 was evaluated in vitro against a panel of melanoma cell lines and was effective in BRAF wild-type as well as BRAF mutant models. When given to C57BL/6 mice at the maximum tolerated dose (MTD) of 15 mg/kg, p.o., qd, BAY 1238097 showed efficacy against the B16/F10 syngeneic model with a T/C of 31% on day 12 post tumor inoculation (T/C≤42% = active according to NCI criteria). In this study, dacarbazine was less active than BAY 1238097 with a T/C of 44%. This was also the case in a patient-derived melanoma model resistant to dacarbazine where BAY 1238097 was found active with 39% T/C. Potent efficacy of BAY 1238097 was also observed against the human LOX-IMVI model in SCID mice either using a daily dose of 15 mg/kg or a q3d schedule at 45 mg/kg (MTD), leading to 10% and 13% T/C, respectively on day 12. Dose-dependent down-regulation of the MYC oncogene was demonstrated ex vivo in B16/F10 tumors as well as in mice peripheral blood mononuclear cells (PBMCs) with maximal effect observed between 3 to 6h post oral treatment with BAY1238097. In addition, strong up-regulation of HEXIM1 mRNA was observed in tumors and PBMCs from the mice. BAY 1238097 was also evaluated in a number of in vitro and in vivo studies in lung cancer cell lines. It was strongly active in KRAS mutant non-small cell lung cancer (NSCLC) (DV-90, NCI-H1373, LCLC-97TM1) and small cell lung cancer (SCLC) models (NCI-H69, NCI-H146, NCI-H526) with IC50 values below 1 μM. Down-regulation of c-Myc protein expression upon treatment with 1 μM was observed in all three sensitive NSCLC models. In the NCI-H1373 model, an induction of caspase 3/7 activity was observed upon 24h of treatment in vitro. In the same model implanted in vivo, a strong reduction of tumor growth was observed following daily oral application of BAY 1238097 (12 mg/kg). The treatment was well tolerated with a T/C of 16% at day 15 after start of treatment. A similar antitumor activity was obtained by applying the compound intravenously twice a week at 100 mg/kg and ex vivo analysis revealed time-dependent regulation of MYC and HEXIM1 after treatment. In vivo efficacy was not limited to NSCLC as daily oral application of BAY 1238097 (10 mg/kg) to the SCLC xenograft model NCI-H526 resulted in high efficacy with 7% T/C on day 21. Taken together, these positive results in preclinical models of melanoma and lung tumors warrant further evaluation of BET inhibition in solid tumors in the clinic. Citation Format: Olaf Klingbeil, Bernard Haendler, Antje Stresemann, Claudia Merz, Annette Walter, Amaury Ernesto Fernandez-Montalvan, Matthias Ocker, Stephan Siegel, Pascale Lejeune. In vivo efficacy of BET inhibitor BAY 1238097 in preclinical models of melanoma and lung cancer. [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 4714.

Abstract CT083: A pivotal randomized phase II study of anetumab ravtansine or vinorelbine in patients with advanced or metastatic pleural mesothelioma after progression on platinum/pemetrexed-based chemotherapy (NCT02610140)

Background: Mesothelioma is a rare but aggressive cancer with a 5-year survival rate less than 10%. Mesothelin is a protein normally present on mesothelial cells and overexpressed in the majority of mesotheliomas. Anetumab ravtansine (BAY 94-9343) is a novel fully human anti-mesothelin IgG1 antibody conjugated to ravtansine, an antitubulin cytotoxic agent. In a phase I study, anetumab ravtansine at 6.5 mg/kg on a q3w IV schedule was well tolerated and showed encouraging durable tumor responses in patients with previously treated mesothelioma. Design: A randomized, open-label, active-controlled, 2-arm, multicenter, phase II trial to evaluate the efficacy and safety of anetumab ravtansine at 6.5 mg Q3W versus vinorelbine 30 mg/m2 QW in patients with advanced or metastatic malignant pleural mesothelioma overexpressing mesothelin and who have progressed on first-line platinum/pemetrexed-based chemotherapy. Objectives: The primary objective is to test the superiority of anetumab ravtansine monotherapy over vinorelbine in progression-free survival (PFS). The secondary objectives of this study include overall survival, patient-reported outcomes (PRO), tumor response, and safety. Exploratory objectives include immunogenicity of anetumab ravtansine, pharmacokinetics, and biomarkers of response. Methods: Biomarker sampling will be performed on all patients to measure tumor mesothelin expression levels at prescreening. Biomarker-positive patients with moderate (2+) and/or strong (3+) level in at least 30% of tumor cells will be randomized and start study treatment following progression after 1st line treatment of platinum/pemetrexed (with or without bevacizumab). Approximately 183 patients meeting eligibility criteria will berandomized in a 2:1 ratio to receive anetumab ravtansine or vinorelbine. Randomization will be stratified by geographic region (Rest of World v. Asia) and time to progression on 1st line treatment (? 6 months vs Results: This trial is open and currently accruing patients. Citation Format: Raffit Hassan, John J. Nemunaitis, Jan P. van Meerbeeck, Ross Jennens, George R. Blumenschein, Jr, Dean A. Fennell, Hedy L. Kindler, Silvia Novello, Cem Elbi, Annette Walter, Danila Serpico, Emma Fountain, Sandra Vingerhoedt, Christine Brown, Jonathan Siegel, Barrett H. Childs. A pivotal randomized phase II study of anetumab ravtansine or vinorelbine in patients with advanced or metastatic pleural mesothelioma after progression on platinum/pemetrexed-based chemotherapy (NCT02610140). [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 CT083.