Katharina Wartha

Targeting tumor-associated macrophages with anti-CSF-1R antibody reveals a strategy for cancer therapy

Macrophage infiltration has been identified as an independent poor prognostic factor in several cancer types. The major survival factor for these macrophages is macrophage colony-stimulating factor 1 (CSF-1). We generated a monoclonal antibody (RG7155) that inhibits CSF-1 receptor (CSF-1R) activation. In vitro RG7155 treatment results in cell death of CSF-1-differentiated macrophages. In animal models, CSF-1R inhibition strongly reduces F4/80(+) tumor-associated macrophages accompanied by an increase of the CD8(+)/CD4(+) T cell ratio. Administration of RG7155 to patients led to striking reductions of CSF-1R(+)CD163(+) macrophages in tumor tissues, which translated into clinical objective responses in diffuse-type giant cell tumor (Dt-GCT) patients.

Development of tetravalent IgG1 dual targeting IGF-1R–EGFR antibodies with potent tumor inhibition

In this study we present novel bispecific antibodies that simultaneously target the insulin-like growth factor receptor type I (IGF-1R) and epidermal growth factor receptor (EGFR). For this purpose disulfide stabilized scFv domains of the EGFR/ADCC antibody GA201 were fused via serine-glycine connectors to the C-terminus of the heavy (XGFR2) or light chain (XGFR4), or the N-termini of the light (XGFR5) or heavy chain (XGFR3) of the IGF-1R antibody R1507 as parental IgG1 antibody. The resulting bispecific IGF-1R-EGFR antibodies XGFR2, XGFR3 and XGFR4 were successfully generated with yields and stability comparable to conventional IgG1 antibodies. They effectively inhibited IGF-1R and EGFR phosphorylation and 3D proliferation of H322M and H460M2 tumor cells, induced strong down-modulation of IGF-1R as well as enhanced EGFR down-modulation compared to the parental EGFR antibody GA201 and were ADCC competent. The bispecific XGFR derivatives showed a strong format dependent influence of N- or C-terminal heavy and light chain scFv attachment on ADCC activity and an increase in receptor downregulation over the parental combination in vitro. XGFR2 and XGFR4 were selected for in vivo evaluation and showed potent anti-tumoral efficacy comparable to the combination of monospecific IGF-1R and EGFR antibodies in subcutaneous BxPC3 and H322M xenograft models. In summary, we have managed to overcome issues of stability and productivity of bispecific antibodies, discovered important antibody fusion protein design related differences on ADCC activity and receptor downmodulation and show that IGF-1R-EGFR antibodies represent an attractive therapeutic strategy to simultaneously target two key components de-regulated in multiple cancer types, with the ultimate goal to avoid the formation of resistance to therapy.

A novel glycoengineered bispecific antibody format for targeted inhibition of epidermal growth factor receptor (EGFR) and insulin-like growth factor receptor type I (IGF-1R) demonstrating unique molecular properties.

Background: Bispecific antibodies are currently emerging as a promising new class of cancer therapeutics. Results: The novel one-arm single chain Fab IgG bispecific antibody (XGFR) targeting IGF-1R and EGFR demonstrated potent signaling inhibition and enhanced ADCC induction. Conclusion: XGFR has shown in vitro and in vivo anti-tumor activity in pancreatic, lung, and colorectal mouse xenograft tumor models. Significance: Rational design can help to overcome low expression yields and impaired effector functions of bispecific antibodies. In the present study, we have developed a novel one-arm single chain Fab heterodimeric bispecific IgG (OAscFab-IgG) antibody format targeting the insulin-like growth factor receptor type I (IGF-1R) and the epidermal growth factor receptor (EGFR) with one binding site for each target antigen. The bispecific antibody XGFR is based on the “knob-into-hole” technology for heavy chain heterodimerization with one heavy chain consisting of a single chain Fab to prevent wrong pairing of light chains. XGFR was produced with high expression yields and showed simultaneous binding to IGF-1R and EGFR with high affinity. Due to monovalent binding of XGFR to IGF-1R, IGF-1R internalization was strongly reduced compared with the bivalent parental antibody, leading to enhanced Fc-mediated cellular cytotoxicity. To further increase immune effector functions triggered by XGFR, the Fc portion of the bispecific antibody was glycoengineered, which resulted in strong antibody-dependent cell-mediated cytotoxicity activity. XGFR-mediated inhibition of IGF-1R and EGFR phosphorylation as well as A549 tumor cell proliferation was highly effective and was comparable with a combined treatment with EGFR (GA201) and IGF-1R (R1507) antibodies. XGFR also demonstrated potent anti-tumor efficacy in multiple mouse xenograft tumor models with a complete growth inhibition of AsPC1 human pancreatic tumors and improved survival of SCID beige mice carrying A549 human lung tumors compared with treatment with antibodies targeting either IGF-1R or EGFR. In summary, we have applied rational antibody engineering technology to develop a heterodimeric OAscFab-IgG bispecific antibody, which combines potent signaling inhibition with antibody-dependent cell-mediated cytotoxicity induction and results in superior molecular properties over two established tetravalent bispecific formats.

RG7386, a novel tetravalent FAP-DR5 antibody, effectively triggers FAP-dependent, avidity-driven DR5 hyperclustering and tumor cell apoptosis

Dysregulated cellular apoptosis and resistance to cell death are hallmarks of neoplastic initiation and disease progression. Therefore, the development of agents that overcome apoptosis dysregulation in tumor cells is an attractive therapeutic approach. Activation of the extrinsic apoptotic pathway is strongly dependent on death receptor (DR) hyperclustering on the cell surface. However, strategies to activate DR5 or DR4 through agonistic antibodies have had only limited clinical success. To pursue an alternative approach for tumor-targeted induction of apoptosis, we engineered a bispecific antibody (BsAb), which simultaneously targets fibroblast-activation protein (FAP) on cancer-associated fibroblasts in tumor stroma and DR5 on tumor cells. We hypothesized that bivalent binding to both FAP and DR5 leads to avidity-driven hyperclustering of DR5 and subsequently strong induction of apoptosis in tumor cells but not in normal cells. Here, we show that RG7386, an optimized FAP-DR5 BsAb, triggers potent tumor cell apoptosis in vitro and in vivo in preclinical tumor models with FAP-positive stroma. RG7386 antitumor efficacy was strictly FAP dependent, was independent of FcR cross-linking, and was superior to conventional DR5 antibodies. In combination with irinotecan or doxorubicin, FAP-DR5 treatment resulted in substantial tumor regression in patient-derived xenograft models. FAP-DR5 also demonstrated single-agent activity against FAP-expressing malignant cells, due to cross-binding of FAP and DR5 across tumor cells. Taken together, these data demonstrate that RG7386, a novel and potent antitumor agent in both mono- and combination therapies, overcomes limitations of previous DR5 antibodies and represents a promising approach to conquer tumor-associated resistance to apoptosis. Mol Cancer Ther; 15(5); 946–57. ©2016 AACR.

Development of metastatic HER2(+) breast cancer is independent of the adaptive immune system.

The tumour‐modulating effects of the endogenous adaptive immune system are rather paradoxical. Whereas some clinical and experimental observations offer compelling evidence for the existence of immunosurveillance, other studies have revealed promoting effects of the adaptive immune system on primary cancer development and metastatic disease. We examined the functional significance of the adaptive immune system as a regulator of spontaneous HER2+ breast tumourigenesis and pulmonary metastasis formation, using the MMTV–NeuT mouse model in which mammary carcinogenesis is induced by transgenic expression of the activated HER2/neu oncogene. Although T and B lymphocytes infiltrate human and experimental HER2+ breast tumours, genetic elimination of the adaptive immune system does not affect development of premalignant hyperplasias or primary breast cancers. In addition, we demonstrate that pulmonary metastasis formation in MMTV–NeuT mice is not dependent on the adaptive immune system. Thus, our findings reveal that spontaneous HER2‐driven mammary tumourigenesis and metastasis formation are neither suppressed, nor altered by immunosurveillance mechanisms, nor promoted by the adaptive immune system. Copyright

XGFR*, a novel affinity-matured bispecific antibody targeting IGF-1R and EGFR with combined signaling inhibition and enhanced immune activation for the treatment of pancreatic cancer

ABSTRACT The epidermal growth factor receptor (EGFR) and the insulin-like growth factor-1 receptor (IGF-1R) play critical roles in tumor growth, providing a strong rationale for the combined inhibition of IGF-1R and EGFR signaling in cancer therapy. We describe the design, affinity maturation, in vitro and in vivo characterization of the bispecific anti-IGF-1R/EGFR antibody XGFR*. XGFR* is based on the bispecific IgG antibody XGFR, which enabled heterodimerization of an IGF-1R binding scFab heavy chain with an EGFR-binding light and heavy chain by the “knobs-into-holes” technology. XGFR* is optimized for monovalent binding of human EGFR and IGF-1R with increased binding affinity for IGF-1R due to affinity maturation and highly improved protein stability to oxidative and thermal stress. It bears an afucosylated Fc-portion for optimal induction of antibody-dependent cell-mediated cytotoxicity (ADCC). Stable Chinese hamster ovary cell clones with production yields of 2–3 g/L were generated, allowing for large scale production of the bispecific antibody. XGFR* potently inhibits EGFR- and IGF-1R-dependent receptor phosphorylation, reduces tumor cell proliferation in cells with heterogeneous levels of IGF-1R and EGFR receptor expression and induces strong ADCC in vitro. A comparison of pancreatic and colorectal cancer lines demonstrated superior responsiveness to XGFR*-mediated signaling and tumor growth inhibition in pancreatic cancers that frequently show a high degree of IGF-1R/EGFR co-expression. XGFR* showed potent anti-tumoral efficacy in the orthotopic MiaPaCa-2 pancreatic xenograft model, resulting in nearly complete tumor growth inhibition with significant number of tumor remissions. In summary, the bispecific anti-IGF-1R/EGFR antibody XGFR* combines potent signaling and tumor growth inhibition with enhanced ADCC induction and represents a clinical development candidate for the treatment of pancreatic cancer.

Rapid activation of tumor-associated macrophages boosts preexisting tumor immunity

Depletion of immunosuppressive tumor-associated macrophages (TAMs) or reprogramming toward a proinflammatory activation state represent different strategies to therapeutically target this abundant myeloid population. In this study, we report that inhibition of colony-stimulating factor-1 receptor (CSF-1R) signaling sensitizes TAMs to profound and rapid reprogramming in the presence of a CD40 agonist before their depletion. Despite the short-lived nature of macrophage hyperactivation, combined CSF-1R+CD40 stimulation of macrophages is sufficient to create a proinflammatory tumor milieu that reinvigorates an effective T cell response in transplanted tumors that are either responsive or insensitive to immune checkpoint blockade. The central role of macrophages in regulating preexisting immunity is substantiated by depletion experiments, transcriptome analysis of ex vivo sorted TAMs, and gene expression profiling of whole tumor lysates at an early treatment time point. This approach enabled the identification of specific combination-induced changes among the pleiotropic activation spectrum of the CD40 agonist. In patients, CD40 expression on human TAMs was detected in mesothelioma and colorectal adenocarcinoma.

Abstract 4573: A novel bispecific Fap-Dr5 antibody inducing potent and tumor-specific death receptor 5 (Dr5) activation by fibroblast activation protein (Fap)-dependent crosslinking

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Background: Activation of the extrinsic apoptosis pathway in tumor cells through agonistic death receptor 5 (DR5) antibodies has been evaluated in the clinic with limited success so far. In this context, several reports show that DR5 activation is strongly dependent on receptor hyperclustering on the cell surface. Therefore a therapeutic principle that induces DR5 hyperclustering specifically at the tumor site may provide superior efficacy, potency and safety compared to conventional DR5 agonistic antibodies. Fibroblast activation protein (FAP) is a marker for activated fibroblasts and abundantly expressed in cancer associated fibroblasts of various epithelial tumor indications and as a tumor antigen on tumors of mesenchymal origin. Due to its relative absence from normal tissues, FAP can be used as a tumor targeting antigen. Here, we are using the broad expression of FAP in tumor stroma for crosslinking of DR5 by a bispecific antibody. Aim: In order to achieve superior tumor targeting and tumor located DR5 hyperclustering we have generated a bispecific antibody, RG7386, comprised of an agonistic DR5 binder and a FAP targeting moiety. Results: RG7386 shows potent and selective binding to FAP and DR5 and can simultaneously bind to both targets. In in vitro co-culture assays, using human DLD-1 colon cancer cells and FAP expressing fibroblasts, RG7386 induces potent, FAP dependent DR5 hyperclustering and apoptosis induction in DR5 positive tumor cells (IC50: 0.05 nM). In preclinical in vivo models with co-injection of DLD-1 tumor cells and fibroblasts as well as patient-derived colorectal cancer models, RG7386 shows FAP dependent efficacy and apoptosis induction superior to conventional DR5 antibodies. Furthermore the superior induction of apoptosis could be confirmed by in vivo and ex vivo analysis of cleaved Caspase-3 with imaging, Luminex and histopathology. Conclusion: RG7386 is a promising novel therapeutic entity for the treatment of solid tumors with FAP positive tumor stroma inducing DR5 activation by FAP dependent DR5 hypercrosslinking which results in potent anti-tumor activity. Citation Format: Katharina Wartha, Barbara Weiser, Thomas Friess, Meher Majety, Valeria Runza, Frank Herting, Thomas Weber, Werner Scheuer, Suzana Vega Harring, Hadassah Sade, Huifeng Niu, Peter Bruenker. A novel bispecific Fap-Dr5 antibody inducing potent and tumor-specific death receptor 5 (Dr5) activation by fibroblast activation protein (Fap)-dependent crosslinking. [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 4573. doi:10.1158/1538-7445.AM2014-4573

Abstract PR04: Targeting tumor-asoociated macrophages with a novel anti-CSF1R antibody in cancer patients

Myeloid cells represent the most abundant immune cell type within the tumor microenvironment of certain tumor entities, including tumor associated macrophages (TAMs). Macrophage infiltration has been identified as an independent poor prognostic factor in several cancer types. The major survival factor for TAMs is macrophage colony stimulating factor 1 (CSF1). We generated a monoclonal antibody (RG7155) that binds to the secondary dimerization interface of CSF1 receptor (CSF1R) as a specific and potent allosteric inhibitor. In vitro, RG7155 treatment results in cell death of CSF1-differentiated macrophages. In animal models, CSF1R inhibition reduced the F4/80+ TAMs infiltrate by 90% and was accompanied by an increase of the CD8+/CD4+ T cell ratio. The ability of RG7155 to reduce TAMs is currently evaluated in a first-in-man phase I clinical study in patients suffering either from pigmented villonodular synovitis (PVNS), a neoplastic disorder characterized by CSF1 overexpression, or other tumor entities. The associated biomarker program involves mandatory paired pre- and on-treatment biopsies of tumor and surrogate skin tissue as well as pharmacodynamic marker assessment in circulating blood. In patients treated with RG7155 an increase of CSF1 associated with a sustained decrease of CD14+CD16+ alternatively activated monocytes in peripheral blood was detected. In PVNS patients administration of RG7155 led to striking reductions of CSF1R+ and CD163+ macrophages in tumor tissue resulting in objective clinical responses according to RECIST (Response Evaluation Criteria in Solid Tumors) in 5 out of 6 patients. All six evaluable PVNS patients showed partial metabolic response in FDG-PET imaging and significant symptomatic improvement as early as 4 weeks after treatment initiation. Furthermore, TAM reduction was also observed in paired tumor samples of patients with various advanced solid malignancies, suggesting broad applicability of this therapeutic approach. This abstract is also presented as Poster A50. Citation Format: Michael Cannarile, Sabine Hoves, Ann-Marie Broeske, Joerg Benz, Katharina Wartha, Valeria Runza, Flora Rey-Giraud, Leon P. Pradel, Friedrich Feuerhake, Irina Klaman, Tobin Jones, Ute Jucknischke, Stefan Scheiblich, Ingo H. Gorr, Antje Walz, Keelara Abiraj, Philippe Cassier, Antonio Sica, Carlos Gomez-Roca, Christophe Le Tourneau, Jean-Pierre Delord, Antoine Italiano, Hyam Levitsky, Jean-Yves Blay, Dominik Ruettinger, Carola H. Ries. Targeting tumor-asoociated macrophages with a novel anti-CSF1R antibody in cancer patients. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr PR04. doi:10.1158/1538-7445.CHTME14-PR04

Abstract LB-212: XGFR, an Fc-engineered dual signaling inhibitor targeting IGF-1R and EGFR

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Background : Elevated signaling via the receptor tyrosine kinases IGF-1R and EGFR has been identified as common characteristic of multiple cancer type. IGF-1R and EGFR signal predominantly through the PI3K and MAPK signaling pathways and thereby mediate growth and survival signals crucial for the development and progression of cancer. There is strong cross talk on multiple levels between IGF-1R and EGFR dependent signaling pathways. Therefore, targeting IGF-1R and EGFR simultaneously is an attractive way to achieve maximal inhibition of signal transduction and to avoid resistance formation. Methods : Bispecific IGF1R-EGFR antibodies were engineered by linking scFv domains of an EGFR Mab (GA201) via Serine-Glycine linkers to an IgG1 IGF-1R Mab (RG1507). The functional properties of the bispecific antibodies were evaluated in cellular in vitro assays (IGF-1R/EGFR phosphorylation, downregulation, 3D proliferation and ADCC assays) and in in vivo xenograft models for tumor growth inhibition and survival. Results : Bispecific IGF-1R-EGFR antibodies (XGFR2, XGFR3, XGFR4) were successfully generated with yields and stability comparable to conventional IgG1 antibodies. XGFR antibodies effectively inhibited IGF-1R and EGFR phosphorylation and 3D proliferation in H322M tumor cells and induced strong downmodulation of IGF-1R and enhanced EGFR downmodulation compared to the parental EGFR antibody GA201. XGFR antibodies showed strong anti-tumor efficacy comparable to the combination of monospecific IGF-1R and EGFR Mabs in the BxPC3 and H322M xenograft models. To enhance the ADCC properties of XGFR, afucosylated, glycoengineered bispecific antibodies with enhanced affinity for FcγRIIIA were generated using the GlycoMab technology. Glycoengineered bispecific antibodies were shown to have superior ADCC properties in in vitro ADCC assays and XGFR4 significantly prolonged median and overall survival of mice in an ADCC competent in vivo model (A549 i.v.). Conclusions : Bispecific IGF-1R-EGFR antibodies represent an attractive therapeutic strategy to simultaneously target two key components of multiple cancer types (IGF-1R and EGFR), resulting in effective inhibition of the PI3K and MAPK signaling pathway and to avoid the formation of resistance to therapy. Having overcome issues of stability and productivity, bispecific antibodies may become an advantageous way to reduce costs and infusion times in cancer therapy, while at the same time, achieving maximal anti-tumor effects through inhibition of multiple targets. 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 LB-212. doi:10.1158/1538-7445.AM2011-LB-212