Development of ISB 1442, a CD38 and CD47 bispecific biparatopic antibody innate cell modulator for the treatment of multiple myeloma

Antibody engineering can tailor the design and activities of therapeutic antibodies for better efficiency or other advantageous clinical properties. Here we report the development of ISB 1442, a fully human bispecific antibody designed to re-establish synthetic immunity in CD38+ hematological malignancies. ISB 1442 consists of two anti-CD38 arms targeting two distinct epitopes that preferentially drive binding to tumor cells and enable avidity-induced blocking of proximal CD47 receptors on the same cell while preventing on-target off-tumor binding on healthy cells. The Fc portion of ISB 1442 is engineered to enhance complement dependent cytotoxicity, antibody dependent cell cytotoxicity and antibody dependent cell phagocytosis. ISB 1442 thus represents a CD47-BsAb combining biparatopic targeting of a tumor associated antigen with engineered enhancement of antibody effector function to overcome potential resistance mechanisms that hamper treatment of myeloma with monospecific anti-CD38 antibodies. ISB 1442 is currently in a Phase I clinical trial in relapsed refractory multiple myeloma.

Abstract 2903: ISB 1442, a first-in-class CD38 and CD47 bispecific antibody innate cell modulator for the treatment of CD38+ malignancies

ISB 1442 is a fully human bispecific antibody (BsAb) using BEAT (Bispecific Engagement by Antibodies based on the T-cell receptor) platform to target CD38 and CD47 as treatment for CD38+ malignancies, including multiple myeloma (MM). ISB 1442 is designed with a bi-paratopic anti-CD38 arm that strongly binds to CD38+ tumor cells and an anti-CD47 arm made of a single Fab designed to block interaction between CD47 and the signal-regulatory protein alpha (SIRPα) with low affinity. This approach is expected to induce minimal unintended effects on red blood cells (RBC) compared to anti-CD47 monoclonal antibody (mAb) magrolimab as it enables the CD47 binding only upon avidity induced CD38 crosslinking. The Fc portion of ISB 1442 is engineered to enhance antibody dependent cell phagocytosis (ADCP), antibody dependent cell cytotoxicity (ADCC) and complement dependent cytotoxicity (CDC). In vitro, ISB 1442 exhibited higher killing potency compared to daratumumab across a range of CD38-expressing tumor cells. Additionally, ISB 1442 showed in vitro tumor killing potency through phagocytosis comparable to magrolimab, acting mostly through ADCP. To assess the complex mechanisms of action of ISB 1442 in a single system, a multiple mode of action of killing (MMoAK) assay was established to allow for simultaneous killing by natural killer cells, autologous macrophages, as well as complement from human serum. In the MMoAK assay, ISB 1442 exhibited tumor cell killing that was twice as high as daratumumab. In vivo, in a therapeutic model of subcutaneously established Raji tumor xenograft in CB17/SCID mice, ISB 1442 induced higher tumor growth inhibition than daratumumab and comparable tumor regression to magrolimab. On-target specificity was evaluated in vitro in human and monkey whole blood assays. ISB 1442 did not cause any detectable hemolysis, RBC depletion or platelet aggregation and showed markedly lower RBC hemagglutination relative to magrolimab, suggesting a more favorable on-target specificity profile in humans. On the contrary, due to the higher expression of CD38 in monkey RBC compared to human, ISB 1442 showed more pronounced binding on RBC than magrolimab, suggesting that monkey is a more sensitive species than human for toxicological evaluation of CD38-targeted therapies. Finally, by integrating in vitro pharmacology data along with available clinical information on benchmark antibodies, a quantitative systems pharmacology model was developed to simulate potential efficacious dose range in MM. In summary, we report a novel approach for the treatment for CD38+ cancers by co-targeting CD38 and CD47. Based on its unique design and multiple mechanisms of action, ISB 1442 is anticipated to enhance antitumor activity by overcoming known primary and acquired tumor escape mechanisms of resistance relative to daratumumab.

Citation Format: Stefano Sammicheli, Camille Grandclement, Elie Dheilly, Maria Panagopoulou, Evangelia Martini, Perrine Suere, Blandine Pouleau, Carole Estoppey, Julia Frei, Jeremy Loyau, Thierry Monney, Adam Drake, Alain Rubod, Marie Agnes Doucey, Vinu Menon, Venkatesha Udupa, Sunitha GN, Daniel Rasmussen, Jeppe Koch Olsen, Roberto Gionannini, Girish Gudi, Ankita Srivastava, Cyril Konto, Mario Perro. ISB 1442, a first-in-class CD38 and CD47 bispecific antibody innate cell modulator for the treatment of CD38+ malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2903.

Nongenetic Evolution Drives Lung Adenocarcinoma Spatial Heterogeneity and Progression

Cancer evolution determines molecular and morphologic intratumor heterogeneity and challenges the design of effective treatments. In lung adenocarcinoma, disease progression and prognosis are associated with the appearance of morphologically diverse tumor regions, termed histologic patterns. However, the link between molecular and histologic features remains elusive. Here, we generated multiomics and spatially resolved molecular profiles of histologic patterns from primary lung adenocarcinoma, which we integrated with molecular data from >2,000 patients. The transition from indolent to aggressive patterns was not driven by genetic alterations but by epigenetic and transcriptional reprogramming reshaping cancer cell identity. A signature quantifying this transition was an independent predictor of patient prognosis in multiple human cohorts. Within individual tumors, highly multiplexed protein spatial profiling revealed coexistence of immune desert, inflamed, and excluded regions, which matched histologic pattern composition. Our results provide a detailed molecular map of lung adenocarcinoma intratumor spatial heterogeneity, tracing nongenetic routes of cancer evolution. SIGNIFICANCE: Lung adenocarcinomas are classified based on histologic pattern prevalence. However, individual tumors exhibit multiple patterns with unknown molecular features. We characterized nongenetic mechanisms underlying intratumor patterns and molecular markers predicting patient prognosis. Intratumor patterns determined diverse immune microenvironments, warranting their study in the context of current immunotherapies.This article is highlighted in the In This Issue feature, p. 1307.

De novo protein design enables the precise induction of RSV-neutralizing antibodies

De novo protein design has been successful in expanding the natural protein repertoire. However, most de novo proteins lack biological function, presenting a major methodological challenge. In vaccinology, the induction of precise antibody responses remains a cornerstone for next-generation vaccines. Here, we present a protein design algorithm called TopoBuilder, with which we engineered epitope-focused immunogens displaying complex structural motifs. In both mice and nonhuman primates, cocktails of three de novo-designed immunogens induced robust neutralizing responses against the respiratory syncytial virus. Furthermore, the immunogens refocused preexisting antibody responses toward defined neutralization epitopes. Overall, our design approach opens the possibility of targeting specific epitopes for the development of vaccines and therapeutic antibodies and, more generally, will be applicable to the design of de novo proteins displaying complex functional motifs.

Cathepsin S Regulates Antigen Processing and T Cell Activity in Non-Hodgkin Lymphoma

Genomic alterations in cancer cells can influence the immune system to favor tumor growth. In non-Hodgkin lymphoma, physiological interactions between B cells and the germinal center microenvironment are coopted to sustain cancer cell proliferation. We found that follicular lymphoma patients harbor a recurrent hotspot mutation targeting tyrosine 132 (Y132D) in cathepsin S (CTSS) that enhances protein activity. CTSS regulates antigen processing and CD4⁺ and CD8⁺ T cell-mediated immune responses. Loss of CTSS activity reduces lymphoma growth by limiting communication with CD4⁺ T follicular helper cells while inducing antigen diversification and activation of CD8⁺ T cells. Overall, our results suggest that CTSS inhibition has non-redundant therapeutic potential to enhance anti-tumor immune responses in indolent and aggressive lymphomas.

Tumor-Directed Blockade of CD47 with Bispecific Antibodies Induces Adaptive Antitumor Immunity

CD47 serves as an anti-phagocytic receptor that is upregulated by cancer to promote immune escape. As such, CD47 is the focus of intense immuno-oncology drug development efforts. However, as CD47 is expressed ubiquitously, clinical development of conventional drugs, e.g., monoclonal antibodies, is confronted with patient safety issues and poor pharmacology due to the widespread CD47 “antigen sink”. A potential solution is tumor-directed blockade of CD47, which can be achieved with bispecific antibodies (biAbs). Using mouse CD47-blocking biAbs in a syngeneic tumor model allowed us to evaluate the efficacy of tumor-directed blockade of CD47 in the presence of the CD47 antigen sink and a functional adaptive immune system. We show here that CD47-targeting biAbs inhibited tumor growth in vivo, promoting durable antitumor responses and stimulating CD8⁺ T cell activation in vitro. In vivo efficacy of the biAbs could be further enhanced when combined with chemotherapy or PD-1/PD-L1 immune checkpoint blockade. We also show that selectivity and pharmacological properties of the biAb are dependent on the affinity of the anti-CD47 arm. Taken together, our study validates the approach to use CD47-blocking biAbs either as a monotherapy or part of a multi-drug approach to enhance antitumor immunity.

Selective Blockade of the Ubiquitous Checkpoint Receptor CD47 Is Enabled by Dual-Targeting Bispecific Antibodies

CD47 is a ubiquitously expressed immune checkpoint receptor that is often upregulated in cancer. CD47 interacts with its counter-receptor SIRPα on macrophages and other myeloid cells to inhibit cancer cell phagocytosis and drive immune evasion. To overcome tolerability and “antigen sink” issues arising from widespread CD47 expression, we generated dual-targeting bispecific antibodies that selectively block the CD47-SIRPα interaction on malignant cells expressing a specific tumor-associated antigen; e.g., CD19 or mesothelin. These bispecific κλ bodies are fully human, native IgG1 molecules, combining tumor targeting and selective CD47 blockade with immune activating mechanisms mediated by the Fc portion of the antibody. CD47-neutralizing κλ bodies efficiently kill cancer cells in vitro and in vivo but interact only weakly with healthy cells expressing physiological levels of CD47. Accordingly, a κλ body administered to non-human primates showed a typical IgG pharmacokinetic profile and was well tolerated. Importantly, κλ bodies preserve their tumoricidal capabilities in the presence of a CD47 antigen sink. Thus, dual-targeting κλ bodies allow for efficacious yet safe targeting of CD47 in cancer. Such a bispecific design could be applied to limit the extent of neutralization of other ubiquitously expressed therapeutic targets.

Abstract B37: NI-1701, a bispecific antibody for selective neutralization of CD47 in B cell malignancies

Upregulation of the immune checkpoint receptor, CD47, on cancer cells promotes immune evasion and is correlated with poor clinical outcome. CD47 is therefore an attractive immuno-oncology target but also a challenging one, given its ubiquitous distribution in healthy tissues. Bispecific antibodies (biAbs) offer superior selectivity as compared to mAbs, as they combine two antigen specificities in one molecule allowing the simultaneous targeting of two cell surface receptors. We used such a dual targeting design to create NI-1701, a biAb that pairs an anti CD47 arm with a high-affinity arm specific for CD19, a clinically validated target expressed by B leukemias and lymphomas. The target cell selectivity of NI-1701 relies principally on the binding affinity of the biAbs anti-CD19 arm. Thus, NI-1701 binds weakly to CD19-negative healthy cells expressing physiological levels of CD47, such as erythrocytes, platelets or T cells. In contrast, NI-1701 binds strongly to CD19-positive cells and blocks CD47 upon concurrent engagement of the two targets at the cell surface. As shown by numerous experiments involving CD19-positive human cancer cell lines and patients cells, NI-1701 effectively kills B cell tumors through antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cell-mediated cytotoxicity (ADCC). Furthermore, NI-1701 controls the growth of sub-cutaneous Raji cell tumors, in a way that was dependent on the co-ligation of both CD19 and CD47 antigens. Examination of the excised tumors revealed that NI-1701 actively reshaped the tumors microenvironment by enhancing the phagocytic activity of macrophages and by reducing the proportion of CD11b+Gr1+myeloid-derived suppressor cells (MDSCs) infiltrating the xenograft tumors. In disseminated mouse models of B-ALL, using both leukemia cell lines and patient-derived xenografts (PDX), NI-1701 was able to reduce tumor burden in peripheral blood and to block the spread of tumor cells to the bone marrow. The therapeutic potential of NI-1701 was also expanded to Diffuse Large B-Cell Lymphoma (DLBCL) using a PDX model, in which the tumor burden was abrogated with significantly higher efficacy than the BTK inhibitor, ibrutinib. In vitro and in vivo studies demonstrated a favorable pharmacokinetic (PK) and tolerability profile of NI-1701. Single and multiple dose studies in non-human primates showed typical IgG PK and no effects on hematological parameters (e.g., red blood cell and platelet counts) up to 100mg/kg, the highest dose tested. Accordingly, in vitro safety testing with human blood showed no evidence of platelet activation or aggregation, hemagglutination or hemolysis event at high antibody concentrations. We also show that NI-1701 target cell selectivity is important for the preservation of tumor cell killing efficacy in the presence of CD47 antigen sink. ADCP and ADCC experiments performed with an excess of bystander CD47-positive cells demonstrate that NI-1701-induced tumor cell killing is not affected by the presence of such antigen sink, in contrast to anti-CD47 mAbs, which loose potency in this situation. We conclude that the dual targeting biAb approach allows a safe yet effective blockade of CD47 due to selectivity for a B cell associated antigen, resulting in impressive tumor cell killing in a range of preclinical models. Thus, dual-targeting biAb open the way to the safe and efficacious therapeutic neutralization of CD47, an immune checkpoint receptor hijacked by cancer cells. NI-1701 is in preclinical enabling studies in preparation for a Phase I clinical study in patients with B cell malignancies, planned for 2017.

Citation Format: Krzysztof Masternak, Xavier Chauchet, Vanessa Buatois, Susana Salgado-Pires, Limin Shang, Zoë Johnson, Elie Dheilly, Valéry Moine, Walter G. Ferlin, Marie H. Kosco-Vilbois, Nicolas Fischer. NI-1701, a bispecific antibody for selective neutralization of CD47 in B cell malignancies. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B37.

Abstract 1495: Neutralization of CD47 in cancer cells with bispecific antibodies harnesses the phagocytic potential of tumor-infiltrating macrophages

The inhibitory “don't eat me” signal of phagocytosis, CD47, is commonly overexpressed in cancer cells, a feature generally associated with poor prognosis. CD47 overexpression in cancer is believed to promote immune evasion by allowing tumor cells to “hide” from innate immune phagocytes like macrophages or dendritic cells. CD47 is therefore a new type of immune checkpoint and an attractive target for cancer immunotherapy. However, as CD47 is also universally expressed on healthy cells, clinical development of anti-CD47 monoclonal antibodies is inevitably limited by toxicity and/or pharmacokinetic issues. To overcome these liabilities, we engineered dual-targeting bispecific antibodies (biAbs) for selective blockade of CD47 in malignant cells. By tethering the biAbs strongly to cells expressing a tumor-associated antigen (TAA), such as CD19 or mesothelin, CD47 is blocked selectively on the target cell. In contrast, as these biAbs will lose the avidity effect with TAA-negative cells, they will bind with very low affinity to healthy cells which express CD47. In this manner, dual-targeting should help to sidestep safety and pharmacokinetic “sink” problems resulting from ubiquitous CD47 expression. Studies in non-human primates performed with the CD47/CD19 therapeutic candidate NI-1701 confirmed this prediction, demonstrating normal IgG1 pharmacokinetics and absence of toxicity, even at high antibody doses (100 mg/kg per week).

Hence, the mechanism of action of CD47/TAA dual-targeting antibodies is heavily contingent upon target co-engagement. In vitro, CD19-positive or mesothelin-positive cancer cells are efficiently killed through antibody dependent cellular phagocytosis (ADCP) and/or antibody-dependent cell-mediated cytotoxicity (ADCC) in the presence of effector cells, such as macrophages or natural killer cells, and the corresponding dual-targeting CD47/TAA antibodies. Their enhanced ability to induce tumor cell phagocytosis was also demonstrated in vivo, in xenograft models: Mice implanted with subcutaneous human B cell lymphoma xenografts controlled tumor growth following therapy with NI-1701, contrary to mice treated with an anti-CD19 mAb. Importantly, tumor microenvironment (TME) studies revealed that mouse macrophages infiltrating human tumors engulfed tumor cells more frequently—and at a significantly higher rate—in animals treated with NI-1701 as compared to controls. Moreover, the observed superior phagocytic activity of tumor-infiltrating macrophages was associated with a reduction of granulocytic myeloid-derived suppressor cell infiltrates, suggesting that NI-1701 may favor the establishment of a tumor-hostile, immunostimulatory TME. We conclude that dual-targeting CD47/TAA bispecific antibodies may open the way to the safe and efficacious therapeutic neutralization of CD47, the universal ‘don't eat me’ signal hijacked by cancer cells.

Citation Format: Krzysztof Masternak, Valéry Moine, Lucile Broyer, Xavier Chauchet, Vanessa Buatois, Elie Dheilly, Stefano Majocchi, Giovanni Magistrelli, Yves Poitevin, Ulla Ravn, Eric Hatterer, Susana Salgado Pires, Limin Shang, Zoë Johnson, Walter Ferlin, Marie Kosco-Vilbois, Nicolas Fischer. Neutralization of CD47 in cancer cells with bispecific antibodies harnesses the phagocytic potential of tumor-infiltrating macrophages. [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 1495.

Abstract 2482: Neutralizing CD47 in cancer cells with dual targeting kappa/lambda bodies

Neutralizing CD47, the ‘don't eat me signal’ hijacked by different tumor types, is a novel generally applicable therapeutic strategy. Because of a distinct mechanism of action and the ability to stimulate the innate anti-tumor immunity, CD47-neutralizing agents are poised as attractive candidates for combination therapies in association with other immunotherapies. However, the development of general CD47 antagonists could be hindered by the ubiquitous and abundant expression of CD47 on virtually all healthy cells. To overcome potential pharmacological and clinical liabilities of a general CD47 antagonist, we have developed bispecific kappa/lambda bodies, which selectively target CD47 in cancer cells. These kappa/lambda bodies:

(i) are full-length bispecific IgGs, (ii) bind with high affinity and neutralize the CD47-SIRP alpha interaction in cancer cells expressing a tumor-associated antigen (TAA), and (iii) mediate efficient cell killing of TAA-positive cancer cells in vitro through Fc-dependent mechanisms such as ADCP (antibody mediated cellular phagocytosis) and ADCC (antibody mediated cellular cytotoxicity).

We are currently developing two molecules of this type, one targeting CD47 and CD19 (for B cell malignancies), the other targeting CD47 and mesothelin (for various mesothelin-positive solid tumors). The efficacy of the CD47/CD19 kappa/lambda body was demonstrated in vivo, using two B-cell lymphoma xenograft models in NOD/SCID mice. We also performed a pharmacokinetics study in non-human primates with the CD47/CD19 lead candidate, with the objective of assessing the potential “antigen sink” effect related to ubiquitous CD47 expression on erythrocytes, platelets and other cells. Encouragingly, the CD47/CD19 kappa/lambda body administered in a single dose to cynomolgus monkeys, at 0.5 and 10 mg/kg, showed an acceptable pharmacokinetic profile and the absence of hematological toxicities. The example of the CD47/CD19 kappa/lambda body illustrates the power of the dual-targeting approach for addressing a ubiquitous cell surface receptor such as CD47.

Citation Format: Krzysztof Masternak, Lucile Broyer, Elie Dheilly, Stefano Majocchi, Valéry Moine, Giovanni Magistrelli, François Rousseau, Ulla Ravn, Franck Gueneau, Pauline Malinge, Sébastien Calloud, Maud Charreton-Galby, Mireille Guerrier, Nessie Costes, Nicolas Bosson, Gérard Didelot, Lucie Bernard, Vanessa Buatois, Laura Cons, Laurence Chatel, Anne Papaioannou, Zoë Johnson, Walter Ferlin, Marie Kosco-Vilbois, Nicolas Fischer. Neutralizing CD47 in cancer cells with dual targeting kappa/lambda bodies. [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 2482. doi:10.1158/1538-7445.AM2015-2482