Bertolt Kreft

Abstract 5200: Preclinical pharmacology of the PSMA-targeted thorium-227 conjugate PSMA-TTC: a novel targeted alpha therapeutic for the treatment of prostate cancer

Prostate-specific membrane antigen (PSMA, FOLH1) is a type II transmembrane glycoprotein of the M28 peptidase family that acts as a glutamate carboxypeptidase on various substrates. PSMA is well established as a target antigen in prostate cancer due to its high and specific overexpression on the surface of prostate cancer cells at all tumor stages, including metastatic and hormone-refractory disease. Several PSMA targeting antibodies and ligands are currently in clinical development or compassionate use therapeutically or as imaging agents. Targeted alpha therapy (TAT) has an established clinical profile with the successful transition of Ra223, an alpha-particle emitter, from bench to bedside in prostate cancer. Thorium-227 is the immediate precursor for Ra223 via alpha-particle emission. We herein describe the generation of a novel TAT, a high energy, alpha-particle emitting PSMA-targeted thorium-227 conjugate (PSMA-TTC). PSMA-TTC consists of a fully human PSMA targeting IgG1 antibody covalently linked via an amide bond to a chelator moiety (3,2 HOPO), enabling radiolabeling with thorium-227 (227Th). PSMA-TTC was prepared in high radiochemical yield and purity and tested for binding affinity to PSMA target (ELISA) as well as PSMA expressing cell lines (FACS). In vitro cytotoxicity experiments were carried out on prostate CA cell lines with different PSMA levels (from 3.000 to 150.000 mAbs bound/ cell). In vivo biodistribution and anti-tumor efficacy were analyzed after i.v. injection of 100-500 kBq/kg at protein doses of 0.14 mg/kg to mice bearing s.c. prostate cancer xenograft models. Additionally, anti-tumor efficacy was evaluated in a PSMA expressing orthotopic bone xenograft model (LNCaP-Luc) monitored by bioluminescence imaging, micro CT and x-ray. PSMA-TTC retains binding affinities to PSMA target and PSMA positive cancer cells similar to the PSMA antibody. Strong in vitro potency and selectivity of PSMA-TTC was shown on different PSMA positive cells. Biodistribution studies in C4-2 xenografts demonstrated specific tumor uptake of PSMA-TTC with a maximum of 50 % of ID/g at t = 72h post dose administration. Selective significant antitumor efficacy was shown for PSMA-TTC in s.c. prostate CA xenograft models with high (C4-2) and medium/low (22Rv1) PSMA protein levels at doses of 250 and 500 kBq/kg. Furthermore, statistically significant prevention of tumor growth was observed after treatment with PSMA-TTC at a dose of 100 kBq/kg in an orthotopic bone xenograft model (LNCaP-Luc). The promising preclinical antitumor activity of PSMA-TTC supports its development for the treatment of patients with metastatic prostate cancer. Citation Format: Stefanie Hammer, Aasmund Larssen, Christine Ellingsen, Solene Geraudie, Derek Grant, Baard Indrevoll, Oliver von Ahsen, Alexander Kristian, Urs B Hagemann, Jenny Karlsson, Roger M Bjerke, Olav B Ryan, Dominik Mumberg, Bertolt Kreft, Alan Cuthbertson. Preclinical pharmacology of the PSMA-targeted thorium-227 conjugate PSMA-TTC: a novel targeted alpha therapeutic for the treatment of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5200. doi:10.1158/1538-7445.AM2017-5200

Abstract 46: Preclinical activity of novel antibody-drug conjugates with pyrrole-based kinesin spindle protein inhibitors targeting different tumor antigens

Antibody-drug conjugates (ADCs) are promising agents that are developed for targeted delivery of cytotoxic payloads to tumor cells. ADCs share a common design of antibody, linker, and cytotoxic payload. Despite significant efforts, the number of available payload classes with a differentiated mode-of-action that can successfully be employed to generate antibody-drug conjugates (ADCs) is still rather limited. So far, only ADCs with microtubule depolymerizing or DNA binding payloads have been approved. The identification of ADC payload classes with a novel mode-of-action will increase therapeutic options and potentially help to overcome resistance. Inhibitors of the kinesin spindle protein (KSP/Eg5/KIF11) have generated interest due to their high anti-tumor activity. However, the transfer of the potency of small molecule KSP inhibitors (KSPis) to highly efficient clinical regimens with a sufficient therapeutic window remains challenging. Through the conjugation of a novel pyrrole subclass of KSPis to antibodies targeting different cancer antigens, we generated a panel of ADCs and characterized them both in vitro and in vivo. ADCs targeting either EGFR or TWEAKR/Fn14 showed strong and specific internalization and displayed specific and potent anti-proliferative efficacy in vitro. In cytotoxicity assays, these ADCs exhibited sub-nanomolar potency in antigen-positive cancer cell lines (EGFR/TWEAKR-pos. NCI-H292; TWEAKR-pos. BxPC3, LoVo) and more than 100-fold selectivity versus non-targeted control-ADC containing the same linker and the same payload. Furthermore, selective anti-tumor efficacy of EGFR- and TWEAKR-KSPi-ADCs was demonstrated in vivo using both cancer cell line-derived models of NSCLC (NCI-H292), urothelial cell carcinoma (UCC) (KU-19-19), and renal cell carcinoma (A498), as well as in the TWEAKR-positive patient-derived xenograft UCC model BFX469. At doses of 5-10 mg/kg qw or bw potent anti-tumor efficacy with treated-to-control ratios (T/C) between 0.16 to 0.28 as well as complete regressions were observed. In summary, KSP inhibitors have been established as a promising new payload class allowing the generation of highly potent and selective ADCs for the treatment of solid tumors. Citation Format: Anette Sommer, Sandra Berndt, Hans-Georg Lerchen, Beatrix Stelte-Ludwig, Sven Wittrock, Anne-Sophie Rebstock, Lisa Dietz, Christoph Mahlert, Simone Greven, Nils Griebenow, Yolanda Cancho-Grande, Rolf Jautelat, Heiner Apeler, Bertolt Kreft. Preclinical activity of novel antibody-drug conjugates with pyrrole-based kinesin spindle protein inhibitors targeting different tumor antigens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 46. doi:10.1158/1538-7445.AM2017-46

Abstract 3234: Development of potent and selective antibody-drug conjugates with pyrrole-based KSP inhibitors as novel payload class

The number of cytotoxic payload classes with different modes-of-action which have been successfully employed in antibody-drug conjugates (ADC) is still rather limited. So far, only ADCs with microtubule inhibitors, DNA binding payloads or topoisomerase I inhibitors have been advanced into clinical testing. To this end, the identification of ADC payload classes with a novel mode of action will increase therapeutic options and potentially help to overcome resistance. Inhibitors of kinesin spindle protein (KSP/Eg5) have generated interest due to their high antitumor potency. However, transferring the preclinical potency of small molecule KSP inhibitors (KSPis) into highly efficient clinical regimens with a sufficient therapeutic window has remained challenging. We have investigated a new pyrrole subclass of KSPis which showed subnanomolar potency against a large panel of tumor cell lines for their utility as a novel payload class in ADCs. Towards this goal different attachment sites for linkers have been explored in the KSPi molecule which were found compatible with cleavable and/or non-cleavable linkers. Subnanomolar potency and selectivity of ADCs with antibodies targeting either HER2, EGFR or TWEAKR could be demonstrated in vitro. For selected ADCs, the intracellular trafficking and metabolite formation was investigated and KSP inhibition was confirmed as the ADC mode of action. Depending on the linker composition differential profiles of the ADC metabolites with regard to efflux, cellular permeation, and bystander effect have been achieved. Moreover, specific accumulation in the tumor versus other tissues was demonstrated in biodistribution studies in vivo. In conclusion, KSP inhibitors have been established as a versatile new payload class for the generation of highly potent and selective ADCs. Citation Format: Hans-Georg Lerchen, Sven Wittrock, Nils Griebenow, Mario Lobell, Anne-Sophie Rebstock, Yolanda Cancho-Grande, Beatrix Stelte-Ludwig, Christoph Mahlert, Simone Greven, Anette Sommer, Sandra Berndt, Carsten Terjung, Heiner Apeler, Bertolt Kreft, Rolf Jautelat. Development of potent and selective antibody-drug conjugates with pyrrole-based KSP inhibitors as novel payload class [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3234. doi:10.1158/1538-7445.AM2017-3234

Abstract 3091: Response of C4.4A-positive patient-derived xenograft models of ESCC, HNSCC and bladder cancer to BAY1129980, a C4.4A-targeted antibody drug conjugate

C4.4A (LYPD3) is a cancer- and metastasis-associated transmembrane cell surface protein which is expressed at high frequency and density in multiple tumor types including squamous and non-squamous non-small cell lung carcinoma ((NSCLC), head & neck squamous cell carcinoma (HNSCC), esophageal squamous cell carcinoma (ESCC) and bladder cancer. C4.4A expression is restricted to a limited number of tissues (e.g. suprabasal layer of skin) making C4.4A an attractive target for the treatment of cancer with a C4.4A-targeted antibody-drug conjugate (ADC). BAY 1129980 (C4.4A-ADC), is an ADC consisting of a fully human C4.4A-targeting monoclonal antibody (technology licensed from BioInvent) conjugated via a novel, non-cleavable alkyl hydrazide linker to a novel, highly potent auristatin W, an antimitotic agent (technology licensed from Seattle Genetics, Inc.). This C4.4A-ADC has been previously shown to be efficacious in C4.4A positive cell line-derived and PDX models of NSCLC. Here we present new preclinical efficacy data of C4.4A-ADC in patient-derived xenograft (PDX) models of ESCC, HNSCC and bladder cancer. Models were selected based on tumor C4.4A levels as determined by mRNA levels and immunohistochemistry (IHC), the latter of which allowed ranking of models according to H-score, percentage of C4.4A positivity, and staining intensity (0 to 3+) in the cell membrane. Representative C4.4A-positive models were selected for in vivo efficacy studies (n=7 each): 4 HNSCC, 4 ESCC and 2 bladder cancers. C4.4A-ADC was administered as one cycle (Q4Dx3) at doses of 7.5 and 15 mg/kg, and efficacy was assessed up to 4 weeks post treatment for optimum tumor growth inhibition (TGI). In ESCC models a response to C4.4A ADC was seen in ES0190 (TGI of 77%; 15mg/kg) and in ES0195 (59%). In HNSCC models an ADC effect on tumor growth was observed in HN10847 (46%), HN9619 (34%), and HN10321 (22%). Finally, both bladder models tested were sensitive to treatment, with a transient response seen in BL0597 (41%) and a strong and complete tumor growth control in BL5001 (93%,) which was superior to cisplatin. The data show that C4.4A-positive PDX models of ESCC, HNSCC and bladder cancer can respond to C4.4A-ADC. C4.4A expression served as a marker for preselection of the models. Nevertheless, other factors may affect response and sensitivity of these tumor models, such as sensitivity to tubulin inhibition, ADC uptake and intracellular processing. In summary, these data support further exploration of the potential of BAY 1129980 in HNSCC, ESCC and bladder cancer in addition to NSCLC. A Phase 1 clinical trial of BAY 1129980 is ongoing (NCT02134197). Citation Format: Joerg Willuda, Carol Pena, Christoph Kneip, Patricia E. Carrigan, Hans-Georg Lerchen, Lars Linden, Bertolt D. Kreft. Response of C4.4A-positive patient-derived xenograft models of ESCC, HNSCC and bladder cancer to BAY1129980, a C4.4A-targeted antibody drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3091. doi:10.1158/1538-7445.AM2017-3091

Abstract 1210: Preclinical pharmacology and repeated dose toxicity of the novel agonistic TWEAK receptor binding antibody BAY-356

TWEAK receptor (TWEAKR, FN14) is a member of the tumor necrosis factor receptor superfamiliy and is highly expressed in a variety of human solid tumor types, and its overexpression is associated with poor prognosis and metastasis. To explore targeting of TWEAKR for cancer therapy we have generated the novel, anti-TWEAKR antibody BAY-356. Its potent agonistic activity leads to TWEAKR hyperactivation and subsequent induction of cell death in vitro and tumor growth inhibition in vivo. BAY-356 is a fully human aglycosylated antibody (Kd ∼ 10nM) that binds to a novel epitope within the TWEAKR ectodomain of various species as determined by BiaCore. In vitro, BAY-356 showed strong agonistic activity on TWEAKR-positive tumor cells, including activation of NFκB- and STAT1 pathways, increase of TWEAKR protein expression, increased IL-8 secretion, caspase 3/7 activation, and proliferation inhibition in a dose-dependent manner. BAY-356 inhibited tumor growth in several TWEAKR-positive tumor models (NCI-H1975, WiDr, ScaBER, and HN10321) with growth inhibition rates of 49-71% when treated with 3-10 mg/kg BAY-356 twice weekly for up to 3 weeks. The activity of BAY-356 was independent of ADCC activation. In a preventative syngeneic CT26-tumor model in Balb/c mice, BAY-356 induced complete responses. Anti-tumor activity of BAY-356 was associated with high tumor levels of TNF alpha protein. To investigate the toxicity of BAY-356, a repeated dose-toxicity study was performed in Cynomolgus monkeys. Animals were dosed with 10, 20, and 40 mg/kg by weekly intravenous injection for 4 weeks. Compound-related clinical findings consisted of an increase of the serum markers amylase and lipase from 10 mg/kg onwards, urea and creatinine from 20 mg/kg onwards and the transaminases ALT and GDPH at 40 mg/kg. Histopathological evaluation revealed focal ductular epithelial hyperplasia with periductular fibrosis in the exocrine pancreas (at 10 & 20 mg/kg), renal tubular hyperplasia and degeneration, Bowman capsule hyperplasia, and glomerulosclerosis in the kidney starting at 10 mg/kg and bile duct hyperplasia in liver at 20 mg/kg and higher. The HNSTD was set as the highest tested dose of 40 mg/kg. Immunohistochemical analysis of TWEAKR expression in these organs demonstrated a dose dependent induction and increase when compared to untreated controls which correlated with the histopathological findings. From these data it can be concluded that hyperactivation of TWEAKR signaling by BAY-356 leading to strong anti-tumor efficacy in various mouse models is invariably accompanied by target-mediated side-effects originating from enhanced TWEAKR induction in in particular in kidneys, pancreas, and liver of sensitive species such as Cynomolgus monkeys. Citation Format: Sandra Berndt, Christian Votsmeier, Ruprecht Zierz, Jakob Walter, Anna-Lena Frisk, Stefanie Hammer, Heiner Apeler, Bertolt Kreft. Preclinical pharmacology and repeated dose toxicity of the novel agonistic TWEAK receptor binding antibody BAY-356. [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 1210.

Abstract DDT02-01: In vitro and in vivo characterization of a novel anti-fibroblast growth factor receptor (FGFR) 2 antibody (BAY 1179470) for the treatment of gastric cancer

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Gastric cancer is the second most common cause of cancer-related mortality worldwide, thus new treatment options are urgently needed. In a subset of gastric cancers, over-expression of fibroblast growth factor receptor 2 (FGFR2), a receptor tyrosine kinase, has been described and may represent a potential therapeutic target for the treatment of FGFR2-positive gastric cancer patients. To this end, we have generated a fully human anti-FGFR2 antibody (BAY 1179470) using the BioInvent Phage Display library. BAY 1179470 binds to a unique FGFR2-specific epitope that is present in all FGFR2 isoforms. Upon binding to FGFR2, BAY 1179470 induces receptor dimerization, internalization and degradation, resulting in significant tumor growth inhibition in vivo in cell line-based and patient-derived gastric cancer models overexpressing FGFR2. Additive anti-tumor efficacy in vivo was achieved by combining BAY 1179470 with either cisplatin or paclitaxel. BAY 1179470 is fully cross-reactive with FGFR2 orthologues of mouse, rat, pig, cynomolgus monkey and rhesus macaque. No significant safety findings have been seen in animal studies. Thus, BAY 1179470 represents a novel anti-FGFR2 antibody with high anti-tumor activity in gastric cancer models and an excellent preclinical safety profile. BAY 1179470 is currently being tested in a first-in-man study in all-comers ([NCT01881217][1]) in Japan. Citation Format: Charlotte Kopitz, Anette Sommer, Stefanie Hammer, Axel Harrenga, Beatrix Stelte-Ludwig, Frank Dittmer, Frank Reetz, Ekkehard May, Ruprecht Zierz, Sabine Wittemer-Rump, Christoph Schatz, H. T. Huynh, Karl Ziegelbauer, Bertolt Kreft. In vitro and in vivo characterization of a novel anti-fibroblast growth factor receptor (FGFR) 2 antibody (BAY 1179470) for the treatment of gastric 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 DDT02-01. doi:10.1158/1538-7445.AM2014-DDT02-01 [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01881217&atom=%2Fcanres%2F74%2F19_Supplement%2FDDT02-01.atom

Abstract 3614: In vivo efficacy of the carbonic anhydrase IX (CA9)-targeted antibody-drug conjugate BAY 79-4620 is superior to that of microtubule inhibitors in preclinical models of NSCLC, gastric and colorectal cancer

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL BAY 79-4620 is a novel antibody drug conjugate (ADC) consisting of a fully human monoclonal antibody directed against carbonic anhydrase IX (CA9) conjugated to the auristatin derivative monomethyl auristatin E (MMAE) and is currently in Phase I clinical testing. CA9 is overexpressed in a range of tumor types, including gastric cancer, non-small cell lung cancer (NSCLC), pancreatic cancer and colorectal cancer. CA9 is a hypoxia-inducible protein regulated by HIF-1α, and its expression has been linked to higher aggressiveness of tumors and is predictive of poor prognosis in several cancers. In this study, we first compared the internalization rates of the ADC BAY 79-4620 and of the naked antibody, which were found to be similar in several cell lines, indicating that CA9 internalization in vitro is not affected by the conjugated toxophore. It has previously been shown that the cytotoxicity of BAY 79-4620 depends on both CA9 expression and sensitivity of tumor cells to tubulin inhibitors. The anti-tumor efficacy of BAY 79-4620 was therefore compared to that of free toxophore MMAE as well as paclitaxel. At cumulative doses corresponding to a fraction of that of paclitaxel (calculated as toxophore equivalents), BAY 79-4620 showed equivalent or superior efficacy to paclitaxel and MMAE in xenograft models of human NSCLC and gastric carcinoma. Cumulative BAY 79-4620 doses corresponding to only 30% of the highest dose of free MMAE given showed equivalent or superior efficacy in xenograft models of non-small cell lung carcinoma. Moreover, BAY 79-4620 also showed efficacy in patient-derived NSCLC models that are resistant to paclitaxel and/or cisplatin. Finally, regrowing CRC tumors after an initial response to BAY 79-4620 responded well to a second cycle of BAY 79-4620 treatment. This indicates that no resistance through clonal selection of CA9 negative tumor cells was induced and that repeated treatment cycles should be possible for cancer patients. These results show the superiority of the CA9-targeted approach over the systemic administration of tubulin inhibitors, component of treatment regimens commonly used for the treatment of NSCLC and gastric cancer. Efficacy of BAY 79-4620 was particularly high in models expressing high levels of CA9, making BAY 79-4620 a promising agent for the treatment of CA9-positive NSCLC and gastric cancer. 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 3614. doi:10.1158/1538-7445.AM2011-3614