Antibody-mediated delivery of immunogenic epitopes to redirect virus-specific CD8+ T-cells towards cancer cells is an emerging and promising new therapeutic strategy. These so-called antibody... Show moreAntibody-mediated delivery of immunogenic epitopes to redirect virus-specific CD8+ T-cells towards cancer cells is an emerging and promising new therapeutic strategy. These so-called antibody-epitope conjugates (AECs) rely on the proteolytic release of the epitopes close to the tumor surface for presentation by HLA class I molecules to eventually redirect and activate virus-specific CD8+ T-cells towards tumor cells. We fused the immunogenic EBV-BRLF1 epitope preceded by a protease cleavage site to the C-terminus of the heavy and/or light chains of cetuximab and trastuzumab. We evaluated these AECs and found that, even though all AECs were able to redirect the EBV-specific T-cells, AECs with an epitope fused to the C-terminus of the heavy chain resulted in higher levels of T-cell activation compared to AECs with the same epitope fused to the light chain of an antibody. We observed that all AECs were depending on the presence of the antibody target, that the level of T-cell activation correlated with expression levels of the antibody target, and that our AECs could efficiently deliver the BRLF1 epitope to cancer cell lines from different origins (breast, ovarian, lung, and cervical cancer and a multiple myeloma). Moreover, in vivo, the AECs efficiently reduced tumor burden and increased the overall survival, which was prolonged even further in combination with immune checkpoint blockade. We demonstrate the potential of these genetically fused AECs to redirect the potent EBV-specific T-cells towards cancer in vitro and in vivo. Show less
Wulp, W. van der; Remst, D.F.G.; Kester, M.G.D.; Hagedoorn, R.S.; Parren, P.W.H.I.; Kasteren, S.I.; ... ; Heemskerk, M.H.M. 2023
Antibody-mediated delivery of immunogenic epitopes to redirect virus-specific CD8+ T-cells towards cancer cells is an emerging and promising new therapeutic strategy. These so-called antibody... Show moreAntibody-mediated delivery of immunogenic epitopes to redirect virus-specific CD8+ T-cells towards cancer cells is an emerging and promising new therapeutic strategy. These so-called antibody-epitope conjugates (AECs) rely on the proteolytic release of the epitopes close to the tumor surface for presentation by HLA class I molecules to eventually redirect and activate virus-specific CD8+ T-cells towards tumor cells. We fused the immunogenic EBV-BRLF1 epitope preceded by a protease cleavage site to the C-terminus of the heavy and/or light chains of cetuximab and trastuzumab. We evaluated these AECs and found that, even though all AECs were able to redirect the EBV-specific T-cells, AECs with an epitope fused to the C-terminus of the heavy chain resulted in higher levels of T-cell activation compared to AECs with the same epitope fused to the light chain of an antibody. We observed that all AECs were depending on the presence of the antibody target, that the level of T-cell activation correlated with expression levels of the antibody target, and that our AECs could efficiently deliver the BRLF1 epitope to cancer cell lines from different origins (breast, ovarian, lung, and cervical cancer and a multiple myeloma). Moreover, in vivo, the AECs efficiently reduced tumor burden and increased the overall survival, which was prolonged even further in combination with immune checkpoint blockade. We demonstrate the potential of these genetically fused AECs to redirect the potent EBV-specific T-cells towards cancer in vitro and in vivo. Show less
King, L.A.; Toffoli, E.C.; Veth, M.; Iglesias-Guimarais, V.; Slot, M.C.; Amsen, D.; ... ; Vliet, H.J. van der 2023
Vy9V82 T cells are effector cells with proven antitumor efficacy against a broad range of cancers. This study aimed to assess the antitumor activity and safety of a bispecific antibody directing... Show moreVy9V82 T cells are effector cells with proven antitumor efficacy against a broad range of cancers. This study aimed to assess the antitumor activity and safety of a bispecific antibody directing Vy9V82 T cells to EGFR-expressing tumors. An EGFR-V82 bispecific T-cell engager (bsTCE) was generated, and its capacity to activate Vy9V82 T cells and trigger antitumor activity was tested in multiple in vitro, in vivo, and ex vivo models. Studies to explore safety were conducted using cross-reactive surrogate engagers in nonhuman primates (NHP). We found that Vy9V82 T cells from peripheral blood and tumor specimens of patients with EGFR thorn cancers had a distinct immune checkpoint expres-sion profile characterized by low levels of PD-1, LAG-3, and TIM-3. Vy9V82 T cells could be activated by EGFR-V82 bsTCEs to mediate lysis of various EGFR thorn patient-derived tumor samples,and substantial tumor growth inhibition and improved survival were observed in in vivo xenograft mouse models using peripheral blood mononuclear cells (PBMC) as effector cells. EGFR-V82 bsTCEs exerted preferential activity toward EGFR thorn tumor cells and induced downstream activation of CD4 thorn and CD8 thorn T cells and natural killer (NK) cells without concomitant activation of suppressive regulatory T cells observed with EGFR-CD3 bsTCEs. Administration of fully cross-reactive and half-life extended surrogate engagers to NHPs did not trigger signals in the safety parameters that were assessed. Considering the effector and immune-activating properties of Vy9V82 T cells, the preclinical efficacy data and acceptable safety profile reported here provide a solid basis for testing EGFR-V82 bsTCEs in patients with EGFR thorn malignancies. Show less
Wulp, W. van der; Gram, A.M.; Bleijlevens, B.; Hagedoorn, R.S.; Araman, C.; Kim, R.Q.; ... ; Heemskerk, M.H.M. 2023
Therapeutic antibody-epitope conjugates (AECs) are promising new modalities to deliver immunogenic epitopes and redirect virus-specific T-cell activity to cancer cells. Nevertheless, many aspects... Show moreTherapeutic antibody-epitope conjugates (AECs) are promising new modalities to deliver immunogenic epitopes and redirect virus-specific T-cell activity to cancer cells. Nevertheless, many aspects of these antibody conjugates require optimization to increase their efficacy. Here we evaluated different strategies to conjugate an EBV epitope (YVL/A2) preceded by a protease cleavage site to the antibodies cetuximab and trastuzumab. Three approaches were taken: chemical conjugation (i.e. a thiol-maleimide reaction) to reduced cysteine side chains, heavy chain C-terminal enzymatic conjugation using sortase A, and genetic fusions, to the heavy chain (HC) C-terminus. All three conjugates were capable of T-cell activation and target-cell killing via proteolytic release of the EBV epitope and expression of the antibody target was a requirement for T-cell activation. Moreover, AECs generated with a second immunogenic epitope derived from CMV (NLV/A2) were able to deliver and redirect CMV specific T-cells, in which the amino sequence of the attached peptide appeared to influence the efficiency of epitope delivery. Therefore, screening of multiple protease cleavage sites and epitopes attached to the antibody is necessary. Taken together, our data demonstrated that multiple AECs could sensitize cancer cells to virus-specific T cells. Show less
Wulp, W. van der; Gram, A.M.; Bleijlevens, B.; Hagedoorn, R.S.; Araman, M.C.; Kim, R.Q.; ... ; Heemskerk, M.H.M. 2023
Therapeutic antibody-epitope conjugates (AECs) are promising new modalities to deliver immunogenic epitopes and redirect virus-specific T-cell activity to cancer cells. Nevertheless, many aspects... Show moreTherapeutic antibody-epitope conjugates (AECs) are promising new modalities to deliver immunogenic epitopes and redirect virus-specific T-cell activity to cancer cells. Nevertheless, many aspects of these antibody conjugates require optimization to increase their efficacy. Here we evaluated different strategies to conjugate an EBV epitope (YVL/A2) preceded by a protease cleavage site to the antibodies cetuximab and trastuzumab. Three approaches were taken: chemical conjugation (i.e. a thiol-maleimide reaction) to reduced cysteine side chains, heavy chain C-terminal enzymatic conjugation using sortase A, and genetic fusions, to the heavy chain (HC) C-terminus. All three conjugates were capable of T-cell activation and target-cell killing via proteolytic release of the EBV epitope and expression of the antibody target was a requirement for T-cell activation. Moreover, AECs generated with a second immunogenic epitope derived from CMV (NLV/A2) were able to deliver and redirect CMV specific T-cells, in which the amino sequence of the attached peptide appeared to influence the efficiency of epitope delivery. Therefore, screening of multiple protease cleavage sites and epitopes attached to the antibody is necessary. Taken together, our data demonstrated that multiple AECs could sensitize cancer cells to virus-specific T cells. Show less
Lameris, R.; Ruben, J.M.; Iglesias-Guimarais, V.; Jong, M. de; Veth, M.; Bovenkamp, F.S. van de; ... ; Vliet, H.J. van der 2023
Bispecific T cell engagers (bsTCEs) hold great promise for cancer treatment but face challenges due to the induction of cytokine release syndrome (CRS), on-target off-tumor toxicity, and the... Show moreBispecific T cell engagers (bsTCEs) hold great promise for cancer treatment but face challenges due to the induction of cytokine release syndrome (CRS), on-target off-tumor toxicity, and the engagement of immuno-suppressive regulatory T cells that limit efficacy. The development of Vy9V52-T cell engagers may overcome these challenges by combining high therapeutic efficacy with limited toxicity. By linking a CD1d-specific single-domain antibody (VHH) to a V52-TCR-specific VHH, we create a bsTCE with trispecific properties, which engages not only Vy9V52-T cells but also type 1 NKT cells to CD1d+ tumors and triggers robust proin-flammatory cytokine production, effector cell expansion, and target cell lysis in vitro. We show that CD1d is expressed by the majority of patient MM, (myelo)monocytic AML, and CLL cells and that the bsTCE triggers type 1 NKT and Vy9V52-T cell-mediated antitumor activity against these patient tumor cells and improves survival in in vivo AML, MM, and T-ALL mouse models. Evaluation of a surrogate CD1d-y5 bsTCE in NHPs shows Vy9V52-T cell engagement and excellent tolerability. Based on these results, CD1d-V52 bsTCE (LAVA-051) is now evaluated in a phase 1/2a study in patients with therapy refractory CLL, MM, or AML. Show less
Antibody function is dependent on avidity - the accumulated strength of multiple affinity interactions between the antibody, antigen, cell surface receptors and other antibodies. In this Review,... Show moreAntibody function is dependent on avidity - the accumulated strength of multiple affinity interactions between the antibody, antigen, cell surface receptors and other antibodies. In this Review, Oostindie et al. discuss the role of avidity in eliciting antibody functional responses and review the current engineering strategies for manipulating avidity interactions in antibody-based therapies.Antibodies are the cardinal effector molecules of the immune system and are being leveraged with enormous success as biotherapeutic drugs. A key part of the adaptive immune response is the production of an epitope-diverse, polyclonal antibody mixture that is capable of neutralizing invading pathogens or disease-causing molecules through binding interference and by mediating humoral and cellular effector functions. Avidity - the accumulated binding strength derived from the affinities of multiple individual non-covalent interactions - is fundamental to virtually all aspects of antibody biology, including antibody-antigen binding, clonal selection and effector functions. The manipulation of antibody avidity has since emerged as an important design principle for enhancing or engineering novel properties in antibody biotherapeutics. In this Review, we describe the multiple levels of avidity interactions that trigger the overall efficacy and control of functional responses in both natural antibody biology and their therapeutic applications. Within this framework, we comprehensively review therapeutic antibody mechanisms of action, with particular emphasis on engineered optimizations and platforms. Overall, we describe how affinity and avidity tuning of engineered antibody formats are enabling a new wave of differentiated antibody drugs with tailored properties and novel functions, promising improved treatment options for a wide variety of diseases. Show less
The hexamerization of natural, human IgG antibodies after cell surface antigen binding can induce activation of the classical complement pathway. Mutations stimulating Fc domain-mediated... Show moreThe hexamerization of natural, human IgG antibodies after cell surface antigen binding can induce activation of the classical complement pathway. Mutations stimulating Fc domain-mediated hexamerization can potentiate complement activation and induce the clustering of cell surface receptors, a finding that was applied to different clinically investigated antibody therapeutics. Here, we biophysically characterized how increased self-association of IgG1 antibody variants with different hexamerization propensity may impact their developability, rather than functional properties. Self-Interaction Chromatography, Dynamic Light Scattering and PEG-induced precipitation showed that IgG variant self-association at neutral pH increased in the order wild type (WT) < E430G < E345K < E345R < E430G-E345R-S440Y, consistent with functional activity. Self-association was strongly pH-dependent, and single point mutants were fully monomeric at pH 5. Differential Scanning Calorimetry and Fluorimetry showed that mutation E430G decreased conformational stability. Interestingly, heat-induced unfolding facilitated by mutation E430G was reversible at 60 degrees C, while a solvent-exposed hydrophobic mutation caused irreversible aggregation. Remarkably, neither increased dynamic self-association propensity at neutral pH nor decreased conformational stability substantially affected the stability of concentrated variants E430G or E345K during storage for two years at 2-8 degrees C. We discuss how these findings may inform the design and development of IgG-based therapeutics. (C) 2022 The Authors. Published by Elsevier Inc. on behalf of American Pharmacists Association. Show less
Surgical resection of the tumor is the primary treatment of colorectal cancer patients. However, we previously demonstrated that abdominal surgery promotes the adherence of circulating tumor cells ... Show moreSurgical resection of the tumor is the primary treatment of colorectal cancer patients. However, we previously demonstrated that abdominal surgery promotes the adherence of circulating tumor cells (CTC) in the liver and subsequent liver metastasis development. Importantly, preoperative treatment with specific tumor-targeting monoclonal antibodies (mAb) prevented surgery-induced liver metastasis development in rats. This study investigated whether the epidermal growth factor receptor (EGFR) represents a suitable target for preoperative antibody treatment of colorectal cancer patients undergoing surgery. The majority of patients with resectable colorectal liver metastases were shown to have EGFR + CTCs. Three different anti-EGFR mAbs (cetuximab, zalutumumab, and panitumumab) were equally efficient in the opsonization of tumor cell lines. Additionally, all three mAbs induced antibody-dependent cellular phagocytosis (ADCP) of tumor cells by macrophages at low antibody concentrations in vitro, independent of mutations in EGFR signaling pathways. The plasma of cetuximab-treated patients efficiently opsonized tumor cells ex vivo and induced phagocytosis. Furthermore, neither proliferation nor migration of epithelial cells was affected in vitro, supporting that wound healing will not be hampered by treatment with low anti-EGFR mAb concentrations. These data support the use of a low dose of anti-EGFR mAbs prior to resection of the tumor to eliminate CTCs without interfering with the healing of the anastomosis. Ultimately, this may reduce the risk of metastasis development, consequently improving long-term patient outcome significantly. Show less
Complement is an important effector mechanism for antibodymediated clearance of infections and tumor cells. Upon binding to target cells, the antibody's constant (Fc) domain recruits complement... Show moreComplement is an important effector mechanism for antibodymediated clearance of infections and tumor cells. Upon binding to target cells, the antibody's constant (Fc) domain recruits complement component C1 to initiate a proteolytic cascade that generates lytic pores and stimulates phagocytosis. The C1 complex (C1qr2s2) consists of the large recognition protein C1q and a heterotetramer of proteases C1r and C1s (C1r2s2). While interactions between C1 and IgG-Fc are believed to be mediated by the globular heads of C1q, we here find that C1r2s2 proteases affect the capacity of C1q to form an avid complex with surface-bound IgG molecules (on various 2,4-dinitrophenol [DNP]-coated surfaces and pathogenic Staphylococcus aureus). The extent to which C1r2s2 contributes to C1q-IgG stability strongly differs between human IgG subclasses. Using antibody engineering of monoclonal IgG, we reveal that hexamer-enhancing mutations improve C1q-IgG stability, both in the absence and presence of C1r2s2. In addition, hexamer-enhanced IgGs targeting S. aureus mediate improved complement-dependent phagocytosis by human neutrophils. Altogether, these molecular insights into complement binding to surface-bound IgGs could be important for optimal design of antibody therapies. Show less
Human immunoglobulin (Ig) G4 usually displays antiinflammatory activity, and observations of IgG4 autoantibodies causing severe autoimmune disorders are therefore poorly understood. In blood, IgG4... Show moreHuman immunoglobulin (Ig) G4 usually displays antiinflammatory activity, and observations of IgG4 autoantibodies causing severe autoimmune disorders are therefore poorly understood. In blood, IgG4 naturally engages in a stochastic process termed "Fab-arm exchange" in which unrelated IgG4s exchange half-molecules continuously. The resulting IgG4 antibodies are composed of two different binding sites, thereby acquiring monovalent binding and inability to cross-link for each antigen recognized. Here, we demonstrate that this process amplifies autoantibody pathogenicity in a classic IgG4-mediated autoimmune disease: muscle-specific kinase (MuSK) myasthenia gravis. In mice, monovalent anti-MuSK IgG4s caused rapid and severemyasthenicmuscleweakness, whereas the same antibodies in their parental bivalent form were less potent or did not induce a phenotype. Mechanistically this could be explained by opposing effects onMuSK signaling. Isotype switching to IgG4 in an autoimmune response thereby may be a critical step in the development of disease. Our study establishes functional monovalency as a pathogenic mechanism in IgG4-mediated autoimmune disease and potentially other disorders. Show less
Weerdt, I. de; Lameris, R.; Ruben, J.M.; Boer, R. de; Kloosterman, J.; King, L.A.; ... ; Vliet, H.J. van der 2021
Purpose: Although considerable progress has been made with autologous T cell-based therapy in B-cell malignancies, application in chronic lymphocytic leukemia (CLL) lags behind due to disappointing... Show morePurpose: Although considerable progress has been made with autologous T cell-based therapy in B-cell malignancies, application in chronic lymphocytic leukemia (CLL) lags behind due to disappointing response rates as well as substantial toxicity that is of particular concern in the elderly CLL population. V gamma 9V delta 2-T cells form a conserved T-cell subset with strong intrinsic immunotherapeutic potential, largely because of their capacity to be triggered by phosphoantigens that can be overproduced by CLL and other malignant cells. Specific activation of V gamma 9V delta 2-T cells by a bispecific antibody may improve the efficacy and toxicity of autologous T-cell-based therapy in CLL.Experimental Design: We evaluated CD1d expression in a cohort of 78 untreated patients with CLL and generated and functionally characterized a CD1d-specific V gamma 9V delta 2-T cell engager based on single-domain antibodies (VHH).Results: CD1d was expressed by CLL in the majority of patients, particularly in patients with advanced disease. The CD1d-specific V gamma 9V delta 2-T cell engager induced robust activation and degranulation of V gamma 9V delta 2- T cells, enabling V gamma 9V delta 2-T cells from patients with CLL to lyse autologous leukemic cells at low effector-to-target ratios. Expression of CD1d on CLL cells is upregulated by all-trans retinoic acid, and sensitizes the malignant cells to bispecific VHH-induced lysis. Furthermore, we provide evidence that the V gamma 9V delta 2-T cell receptor retains responsiveness to phosphoantigens when the bispecific VHH is bound, and aminobisphosphonates can therefore enhance bispecific V gamma 9V delta 2-T cell engager-mediated tumor-specific killing.Conclusions: Collectively, our data demonstrate the immunotherapeutic potential of this novel CD1d-specific V gamma 9V delta 2-T cell engager in CLL. Show less
Weerdt, I. de; Lameris, R.; Scheffer, G.L.; Vree, J.; Boer, R. de; Stam, A.G.; ... ; Vliet, H.J. van der 2021
Novel T cell-based therapies for the treatment of B-cell malignancies, such as chronic lymphocytic leukemia (CLL) and multiple myeloma (MM), are thought to have strong potential. Progress, however,... Show moreNovel T cell-based therapies for the treatment of B-cell malignancies, such as chronic lymphocytic leukemia (CLL) and multiple myeloma (MM), are thought to have strong potential. Progress, however, has been hampered by low efficacy and high toxicity. Tumor targeting by V gamma 9V delta 2 T cells, a conserved T-cell subset with potent intrinsic antitumor properties, mediated by a bispecific antibody represents a novel approach promising high efficacy with limited toxicity. Here, we describe the generation of a bispecific V gamma 9V delta 2 T-cell engager directed against CD40, which, due to its overexpression and biological footprint in malignant B cells, represents an attractive target. The CD40-targeting moiety of the bispecific antibody was selected because it can prevent CD4OL-induced prosurvival signaling and reduce CD40-mediated resistance of CLL cells to venetoclax. Selective activation of V gamma 9V delta 2 T cells in the presence of CD40(+) tumor cells induced potent V gamma 9V delta 2 T-cell degranulation, cytotoxicity against CLL and MM cells in vitro, and in vivo control of MM in a xenograft model. The CD40-bispecific gamma delta T-cell engager demonstrated lysis of leukemic cells by autologous V gamma 9V delta 2 T cells present in patient-derived samples. Taken together, our CD40 bispecific gamma delta T-cell engager increased the sensitivity of leukemic cells to apoptosis and induced a potent V gamma 9V delta 2 T cell-dependent antileukemic response. It may, therefore, represent a potential candidate for the development of novel treatments for B-cell malignancies. Show less
Higher-order death receptor 5 (DR5) clustering can induce tumor cell death; however, therapeutic compounds targeting DR5 have achieved limited clinical efficacy. We describe HexaBody-DR5/DR5, an... Show moreHigher-order death receptor 5 (DR5) clustering can induce tumor cell death; however, therapeutic compounds targeting DR5 have achieved limited clinical efficacy. We describe HexaBody-DR5/DR5, an equimolar mixture of two DR5-specific IgG1 antibodies with an Fc-domain mutation that augments antibody hexamerization after cell surface target binding. The two antibodies do not compete for binding to DR5 as demonstrated using binding competition studies, and binding to distinct epitopes in the DR5 extracellular domain was confirmed by crystallography. The unique combination of dual epitope targeting and increased IgG hexamerization resulted in potent DR5 agonist activity by inducing efficient DR5 outside-in signaling and caspase-mediated cell death. Preclinical studies in vitro and in vivo demonstrated that maximal DR5 agonist activity could be achieved independent of Fc gamma receptor-mediated antibody crosslinking. Most optimal agonism was observed in the presence of complement complex C1, although without inducing complement-dependent cytotoxicity. It is hypothesized that C1 may stabilize IgG hexamers that are formed after binding of HexaBody-DR5/DR5 to DR5 on the plasma membrane, thereby strengthening DR5 clustering and subsequent outside-in signaling. We observed potent antitumor activity in vitro and in vivo in large panels of patient-derived xenograft models representing various solid cancers. The results of our preclinical studies provided the basis for an ongoing clinical trial exploring the activity of HexaBody-DR5/DR5 (GEN1029) in patients with malignant solid tumors. Show less
Tetraspanin CD37 has recently received renewed interest as a therapeutic target for B-cell malignancies. Although complement-dependent cytotoxicity (CDC) is a powerful Fc-mediated effector function... Show moreTetraspanin CD37 has recently received renewed interest as a therapeutic target for B-cell malignancies. Although complement-dependent cytotoxicity (CDC) is a powerful Fc-mediated effector function for killing hematological cancer cells, CD37-specific antibodies are generally poor inducers of CDC. To enhance CDC, the E430G mutation was introduced into humanized CD37 monoclonal IgG1 antibodies to drive more efficient IgG hexamer formation through intermolecular Fc-Fc interactions after cell surface antigen binding. DuoHexaBody-CD37, a bispecific CD37 antibody with the E430G hexamerization-enhancing mutation targeting two non-overlapping epitopes on CD37 (biparatopic), demonstrated potent and superior CDC activity compared to other CD37 antibody variants evaluated, in particular ex vivo in patient-derived chronic lymphocytic leukemia cells. The superior CDC potency was attributed to enhanced IgG hexamerization mediated by the E430G mutation in combination with dual epitope targeting. The mechanism of action of DuoHexaBody-CD37 was shown to be multifaceted, as it was additionally capable of inducing efficient antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis in vitro. Finally, potent anti-tumor activity in vivo was observed in cell line- and patient-derived xenograft models from different B-cell malignancy subtypes. These encouraging preclinical results suggest that DuoHexaBody-CD37 (GEN3009) may serve as a potential therapeutic antibody for the treatment of human B-cell malignancies. Show less
Activation of membrane receptors through clustering is a common mechanism found in various biological systems. Spatial proximity of receptors may be transduced across the membrane to initiate... Show moreActivation of membrane receptors through clustering is a common mechanism found in various biological systems. Spatial proximity of receptors may be transduced across the membrane to initiate signaling pathways or alternatively be recognized by peripheral proteins or immune cells to trigger external effector functions. Here we show how specific immunoglobulin G (IgG) binding induces clustering of monomeric target molecules in lipid membranes through Fc- Fc interactions. We visualize and characterize the dynamic IgG oligomerization process and the molecular interactions involved using high-speed atomic force microscopy, single-molecule force spectroscopy, and quartz crystal microbalance experiments. We found that the Fc-Fc interaction strength is precisely tuned to be weak enough to prevent IgG oligomerization in solution at physiological titers, but enabling IgG oligomerization when Fabs additionally bind to their cognate surface epitopes, a mechanism that ultimately targets IgG-mediated effector functions such as classical complement activation to antigenic membranes. Show less
Targeted therapies and immunotherapy have shown promise in patients with non-small cell lung cancer (NSCLC). However, the majority of patients fail or become resistant to treatment, emphasizing the... Show moreTargeted therapies and immunotherapy have shown promise in patients with non-small cell lung cancer (NSCLC). However, the majority of patients fail or become resistant to treatment, emphasizing the need for novel treatments. In this study, we confirm the prognostic value of levels of AXL, a member of the TAM receptor tyrosine kinase family, in NSCLC and demonstrate potent antitumor activity of the AXL-targeting antibody-drug conjugate enapotamab vedotin across different NSCLC subtypes in a mouse clinical trial of human NSCLC. Tumor regression or stasis was observed in 17/61 (28%) of the patient-derived xenograft (PDX) models and was associated with AXL mRNA expression levels. Significant single-agent activity of enapotamab vedotin was validated in vivo in 9 of 10 AXL-expressing NSCLC xenograft models. In a panel of EGFR-mutant NSCLC cell lines rendered resistant to EGFR inhibitors in vitro, we observed de novo or increased AXL protein expression concomitant with enapotamab vedotin-mediated cytotoxicity. Enapotamab vedotin also showed antitumor activity in vivo in 3 EGFR-mutant, EGFR inhibitor-resistant PDX models, including an osirnertinib-resistant NSCLC PDX model. In summary, enapotamab vedotin has promising therapeutic potential in NSCLC. The safety and preliminary efficacy of enapotamab vedotin are currently being evaluated in the clinic across multiple solid tumor types, including NSCLC. Show less
CD20 monoclonal antibody therapies have significantly improved the outlook for patients with B-cell malignancies. However, many patients acquire resistance, demonstrating the need for new and... Show moreCD20 monoclonal antibody therapies have significantly improved the outlook for patients with B-cell malignancies. However, many patients acquire resistance, demonstrating the need for new and improved drugs. We previously demonstrated that the natural process of antibody hexamer formation on targeted cells allows for optimal induction of complement-dependent cytotoxicity. Complement-dependent cytotoxicity can be potentiated by introducing a single point mutation such as E430G in the IgG Fc domain that enhances intermolecular Fc-Fc interactions between cell-bound IgG molecules, thereby facilitating IgG hexamer formation. Antibodies specific for CD37, a target that is abundantly expressed on healthy and malignant B cells, are generally poor inducers of complement-dependent cytotoxicity. Here we demonstrate that introduction of the hexamerization-enhancing mutation E430G in CD37-specific antibodies facilitates highly potent complement-dependent cytotoxicity in chronic lymphocytic leukemia cells ex vivo. Strikingly, we observed that combinations of hexamerization-enhanced CD20 and CD37 antibodies cooperated in C1q binding and induced superior and synergistic complement-dependent cytotoxicity in patient-derived cancer cells compared to the single agents. Furthermore, CD20 and CD37 antibodies colocalized on the cell membrane, an effect that was potentiated by the hexamerization-enhancing mutation. Moreover, upon cell surface binding, CD20 and CD37 antibodies were shown to form mixed hexameric antibody complexes consisting of both antibodies each bound to their own cognate target, so-called hetero-hexamers. These findings provide novel insights into the mechanisms of synergy in antibody-mediated complement-dependent cytotoxicity and provide a rationale to explore Fc-engineering and antibody hetero-hexamerization as a tool to enhance the cooperativity and therapeutic efficacy of antibody combinations. Show less
