Agonistic CD40 Antibody Research Articles

Abstract A14: Irreversible electroporation is an “in situ vaccine” and induces antitumor immune responses in pancreatic cancer

Abstract The pancreatic cancer (PC) microenvironment is notoriously immunosuppressive and responds poorly to conventional checkpoint blockade immunotherapy, necessitating a need to overcome this challenge. Irreversible electroporation (IRE) is a nonthermal method of inducing cell death that is currently being used clinically for selected patients with locally advanced PC. Using a robust syngeneic mouse model of PC using cells established from a tumor arising in an LSL-KrasG12D/+; LSL-Trp53R172H/+; PDX1Cre/+; LSL-ROSA26 Luc/+ mouse (KPC), we have demonstrated that IRE alone can serve as an “in situ vaccine” and induce systemic immune responses that prevent secondary tumor growth (prophylactic immunity). We have furthermore demonstrated that these effects are augmented by combination with innate immune activators and PD-1 checkpoint blockade. We observed a significant decrease in immunosuppressive myeloid-derived suppressor cells (MDSCs) (CD11b+, CD11c-, GR1+) at one week in the IRE and drug alone groups with an additive effect in the combination groups. We also saw a profound shift in the ratio of immunostimulatory M1 (MHC II+, CD206 lo): immunosuppressive M2 (MHC II -, CD206 hi) macrophages in the combination groups and a modest increase in CD8+ T cells with IRE alone that was almost doubled in the combination groups with a concomitant decrease in T regulatory cells. Using exome and RNA sequencing of the KPC tumors expressed, nonsynonymous mutations in these tumors were identified and 101 long peptides (20 mer) were generated harboring these mutations at positions 9 and 15. When the CD8+ T-cells post-IRE were incubated along with these mutant peptides and bone marrow-derived dendritic cells, we were able to observe that these T cells were reactive (Interferon gamma secretion) to these neoantigenic peptide pools. Further, we were able to identify specific mutant peptides against which T-cell response was stimulated post IRE that were similar or even better than vaccinating the mice with irradiated KPC cells, suggesting that IRE induced tumor neoantigen-specific prophylactic immune response. Specifically, local delivery of toll-like receptor 7 (TLR7) agonist (1V270) and agonistic CD40 antibody resulted in complete regression of treated primary tumors in 7/10 mice in the experimental group. Increased presence of CD8+ dendritic cells (CD45+ CD11C+) in the draining lymph node suggested that the agonistic CD40 antibody could have triggered increased dendritic cell maturation and cross-presentation. Moreover, it resulted in the complete elimination of the untreated secondary tumors in the group, which IRE as a monotherapy failed to achieve, showing that with appropriate combination strategies, successful therapeutic systemic antitumor immunity can also be achieved with IRE to be used for the management of metastatic PC in the near future. Citation Format: Jayanth S. Shankara Narayanan, Aaron Miller, Tomoko Hayashi, Partha Ray, Stephen Schoenberger, Dennis Carson, Rebekah White. Irreversible electroporation is an “in situ vaccine” and induces antitumor immune responses in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A14.

Abstract IA15: Vascular reprogramming for enhancing cancer immunotherapy

Abstract Immune checkpoint blockade can reinvigorate the tumor-antagonizing functions of T cells and be potentially curative, but the majority of the tumors are either refractory or become resistant to the treatment. Among various parameters, the lack of pre-existing T-cell infiltrates may determine tumor refractoriness to immune checkpoint blockade and other cancer immunotherapies. Increasing data indicate that angiogenic blood vessels can limit the infiltration and functionality of T cells in tumors. For example, high intratumoral VEGFA levels make the tumor blood vessels dysfunctional and poorly permissive to T-cell extravasation, in part through the downregulation of T-cell adhesion molecules on the vascular endothelium. Besides VEGFA, angiopoietin-2 (ANGPT2) also induces abnormal tumor angiogenesis. Accordingly, combined blockade of VEGFA and ANGPT2 reprograms the tumor blood vessels to a form that is conducive to improved T-cell activation and trafficking and enhances tumor response to both immune checkpoint blockade (anti-PD-1) and agonistic CD40 antibodies in several genetically defined mouse cancer models. In my lecture I will discuss the applications, prospects, and current limitations of antiangiogenic immunotherapies. Citation Format: Michele De Palma. Vascular reprogramming for enhancing cancer immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr IA15.

Single-Cell Analyses Inform Mechanisms of Myeloid-Targeted Therapies in Colon Cancer

Single-cell RNA sequencing (scRNA-seq) is a powerful tool for defining cellular diversity in tumors, but its application toward dissecting mechanisms underlying immune-modulating therapies is scarce. We performed scRNA-seq analyses on immune and stromal populations from colorectal cancer patients, identifying specific macrophage and conventional dendritic cell (cDC) subsets as key mediators of cellular cross-talk in the tumor microenvironment. Defining comparable myeloid populations in mouse tumors enabled characterization of their response to myeloid-targeted immunotherapy. Treatment with anti-CSF1R preferentially depleted macrophages with an inflammatory signature but spared macrophage populations that in mouse and human expresses pro-angiogenic/tumorigenic genes. Treatment with a CD40 agonist antibody preferentially activated a cDC population and increased Bhlhe40+ Th1-like cells and CD8+ memory Tcells. Our comprehensive analysis of key myeloid subsets in human and mouse identifies critical cellular interactions regulating tumor immunity and defines mechanisms underlying myeloid-targeted immunotherapies currently undergoing clinical testing.

A phase II trial with safety lead-in to evaluate the addition of APX005M, a CD40 agonistic monoclonal antibody, to standard-of-care doxorubicin chemotherapy for the treatment of advanced soft tissue sarcoma.

TPS85 Background: Soft tissue sarcoma (STS) is a biologically heterogeneous disease for which existing immunotherapy approaches (e.g. anti-PD-1) have shown limited clinical activity. Cytotoxic chemotherapy with doxorubicin (D), an anthracycline, remains standard-of-care treatment for most advanced STS. Combining chemotherapy with immunomodulatory treatments may enhance antigen presentation and favorably impact the immune microenvironment (iME). APX005M (Apexigen; San Carlos, CA) is a novel CD40 agonistic antibody. Preclinically, CD40 ligation plus chemotherapy induced expression of costimulatory and major histocompatibility complex molecules on antigen presenting cells (APCs), shifted the myeloid compartment towards an M1 phenotype and expanded T-cell receptor clonality, which are characteristics in which the sarcoma iME is deficient (2,3). In phase 1, APX005M showed dose-dependent activation of APCs in peripheral blood and favorable tolerability. We designed a phase II study evaluating D+A as a novel combination for STS. Methods: This is a single-arm, open-label, Simon 2 stage phase II study with safety lead-in evaluating D+A among 27 patients with STS. Pts have advanced STS (excluding GIST and Kaposi sarcoma) for which doxorubicin is appropriate and any prior lines of therapy, including none. Pts receive D 75 mg/m2 and A 0.3 mg/m2 IV day 1 in 21 day cycles. Doxorubicin is stopped after cycle 8 but APX005M may continue. The primary endpoint is the objective response rate (ORR). The study design has power of 85% to show an improvement in ORR from 10% (inactive) to 30% (active) with α = 0.04. Secondary endpoints include PFS and safety. Pts undergo collection of stool specimens at baseline and cycle 3 to evaluate composition of the gut microbiome including effects on clinical outcomes and modulation of microbiome by treatment. Pts undergo paired tumor biopsies at baseline and cycle 2 which are evaluated with gene expression and multiplex immunohistochemistry to evaluate effects of D+A on iME. The study opened in 1/2019. Clinical trial information: NCT03719430.

Antiangiogenic immunotherapy suppresses desmoplastic and chemoresistant intestinal tumors in mice.

Mutations in APC promote colorectal cancer (CRC) progression through uncontrolled WNT signaling. Patients with desmoplastic CRC have a significantly worse prognosis and do not benefit from chemotherapy, but the mechanisms underlying the differential responses of APC-mutant CRCs to chemotherapy are not well understood. We report that expression of the transcription factor prospero homeobox 1 (PROX1) was reduced in desmoplastic APC-mutant human CRCs. In genetic Apc-mutant mouse models, loss of Prox1 promoted the growth of desmoplastic, angiogenic, and immunologically silent tumors through derepression of Mmp14. Although chemotherapy inhibited Prox1-proficient tumors, it promoted further stromal activation, angiogenesis, and invasion in Prox1-deficient tumors. Blockade of vascular endothelial growth factor A (VEGFA) and angiopoietin-2 (ANGPT2) combined with CD40 agonistic antibodies promoted antiangiogenic and immunostimulatory reprogramming of Prox1-deficient tumors, destroyed tumor fibrosis, and unleashed T cell-mediated killing of cancer cells. These results pinpoint the mechanistic basis of chemotherapy-induced hyperprogression and illustrate a therapeutic strategy for chemoresistant and desmoplastic CRCs.

CD40 Enhances Type I Interferon Responses Downstream of CD47 Blockade, Bridging Innate and Adaptive Immunity.

Disrupting the binding of CD47 to SIRPα has emerged as a promising immunotherapeutic strategy for advanced cancers by potentiating antibody-dependent cellular phagocytosis (ADCP) of targeted antibodies. Preclinically, CD47/SIRPα blockade induces antitumor activity by increasing the phagocytosis of tumor cells by macrophages and enhancing the cross-presentation of tumor antigens to CD8+ T cells by dendritic cells; both of these processes are potentiated by CD40 signaling. Here we generated a novel, two-sided fusion protein incorporating the extracellular domains of SIRPα and CD40L, adjoined by a central Fc domain, termed SIRPα-Fc-CD40L. SIRPα-Fc-CD40L bound CD47 and CD40 with high affinity and activated CD40 signaling in the absence of Fc receptor cross-linking. No evidence of hemolysis, hemagglutination, or thrombocytopenia was observed in vitro or in cynomolgus macaques. Murine SIRPα-Fc-CD40L outperformed CD47 blocking and CD40 agonist antibodies in murine CT26 tumor models and synergized with immune checkpoint blockade of PD-1 and CTLA4. SIRPα-Fc-CD40L activated a type I interferon response in macrophages and potentiated the activity of ADCP-competent targeted antibodies both in vitro and in vivo These data illustrated that whereas CD47/SIRPα inhibition could potentiate tumor cell phagocytosis, CD40-mediated activation of a type I interferon response provided a bridge between macrophage- and T-cell-mediated immunity that significantly enhanced durable tumor control and rejection.

Modulating Cholangiocarcinoma's Tumor Microenvironment Enhances Response To Immune Checkpoint Blockade

Presenter: Laurence Diggs MD | National Institutes of Health Background: Intrahepatic cholangiocarcinoma (iCCA) carries a very poor prognosis due to a typically late clinical presentation and a poor response to current therapeutics. ICCA’s tumor microenvironment (TME) has been shown to be immunosuppressive. While these tumors commonly express PD-1 and PD-L1, the response to immune checkpoint inhibitors (ICI) is poor. We hypothesized that modulating the TME by stimulating antigen-presenting cells (APCs) can improve response to ICIs. Specifically, stimulating CD40, a known receptor on all APCs, can drive increased effector cell cytotoxicity when combined with ICI. Methods: We treated tumor bearing C57BL/6 mice with a CD40 agonistic antibody, an anti-PD1 antibody, and the combination (CD40/PD1) to compare treatment response. We used three different mouse models including subcutaneous and orthotopic injections of SB1, an established iCCA cell line as well as hydrodynamic tail vein injection of the YAP and AKT plasmids. Mice were then treated for three weeks with a CD40 agonist (2.5ug/g) weekly, an anti-PD-1 (10ug/g) weekly or the combination starting on post-tumor inoculation day five. Tumors were measured, weighed and evaluated histologically for differences between treated and untreated mice. Tumors were histologically proven iCCA (CK7 +, CK19+, HNF4α-). Immunohistochemical (IHC) staining characterized the TME including lymphocytes (CD4&CD8 T cells, B cells), myeloid cells (macrophages, dendritic cells), as well as PD-1 and CD-40 expression. Flow cytometric analysis of lymphoid and myeloid cell populations including activation status was performed. qPCR allowed for the identification of the cytokine mediators of treatment response. Finally, CD4, and CD8 T cell depletion was undertaken to identify effector cells. Results: In subcutaneous, orthotopic, and plasmid models, mice treated with anti-PD-1 alone did not demonstrate significantly (p>0.05) lower tumor burden. Mice did exhibit a response to monotherapy with a CD40 agonist (p<0.05). When these agents were combined (CD40/PD-1) however, a significantly greater reduction in tumor burden was seen (p<0.05) (Figure 1). IHC confirmed iCCA with increased areas of necrosis and calcification in CD40/PD-1 in the liver tumor tissue of treated mice. Flow cytometry demonstrated increased CD4+ and CD8+ T cells presence and activation as well as increased activation of myeloid cells in CD40/PD-1 treated mice. qPCR revealed increased presence of IL-2, TNF, iNOS, and Granzyme B within the tumor tissue and lymphocytes of mice treated with CD40/PD-1. T cell depletion demonstrated reduced efficacy of treatment with CD8 depletion and complete loss of efficacy of treatment with CD4 depletion (p<0.05). Conclusion: In Conclusion, modulation of the TME by CD40-mediated activation of APCs in iCCA appears to activate T cells and significantly enhances response to anti-PD-1 therapy. This process appears to be mediated both by CD4+ and CD8+ T cells. These findings offer a potential alternative to current cytotoxic chemotherapy regimens.

Abstract PR04: STING and TLR-independent activation of T-cell responses against pancreatic cancer using agonistic CD40 antibody

Abstract Immunotherapy is increasingly used in combination with current standard-of-care treatments such as chemotherapy that likely provides danger signals via immunogenic tumor cell death and activation of STING or TLR pathways. However, both the toxicity and immunosuppressive effects of chemotherapy risks hindering clinical benefit. Agonistic CD40 antibody is a potent activator of immune responses, acting upstream of immune checkpoint blockade (ICB) by driving T-cell priming. Here, we show that anti-CD40 is sufficient to drive potent T-cell responses against murine KPC (KrasG12D;Trp53R172H;Pdx-Cre) pancreatic tumors if combined with ICB. CD40/ICB was more effective than CD40/ICB/chemotherapy (median overall survival 76 days vs. 44 days in CD40/ICB vs. CD40/ICB/chemotherapy-treated mice, p&amp;lt;0.01). Therapeutic efficacy of CD40/ICB was fully independent of the STING, MyD88, and IFNAR pathways, requiring instead host expression of CD40, cross-presenting dendritic cells, and an intact T-cell compartment. Therapy-induced CD4 and CD8 T cell responses displayed enhanced polyfunctional cytokine secretion (48.9% vs. 29.5% of CD8+ T cells in vehicle control treated mice), cleared established primary tumors (43% vs. 0% in vehicle control or single-treatment cohorts p&amp;lt;0.0001), and formed protective memory responses in 57% of CD40/ICB cured mice. Immunosuppressive regulatory T cells were noticeably absent from the tumor site after CD40 treatment (7% of CD4+ T cells vs. 33% in mice treated with ICB alone, p&amp;lt;0.01), concomitant with improved T-cell activation and proliferation, whereas ICB was needed to potentiate the full activation and reinvigoration of the T-cell response both locally and systemically. The efficacy of CD40/ICB in in this ICB-resistant KPC model opens the possibility of optimized immunotherapy regimens free of the toxicity and immunosuppressive effects of cytotoxic therapy. This abstract is also being presented as Poster B08. Citation Format: Katelyn T. Byrne, Alexander H. Morrison, Robert H. Vonderheide. STING and TLR-independent activation of T-cell responses against pancreatic cancer using agonistic CD40 antibody [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr PR04.

Accelerated elimination of human cancer cells by a CD40 agonist antibody combined with a PD-1 antagonist in CD4-depleted mice.

The elimination of residual microscopic cancer cells is important cancer treatment. The immunoediting theory describes the balance between the immune system and cancer cells. The current study investigated changes in the immune system during the elimination of cancer cells and evaluated the influence of cluster of differentiation (CD)4 or CD8 depletion. A human squamous cell cancer cell line (SNU1041) was injected in the lateral tongue of immunocompetent mice and the changes in the CD4, CD8, CD11b, CD19, CD40 and CD40 ligand (L) populations in the blood, lymph nodes and spleen were evaluated using flow cytometry, and changes in serum cytokine levels were evaluated using a magnetic bead panel. Cancer cell elimination was delayed by CD4 depletion but not by CD8 depletion. The CD8-depleted group indicated increased levels of CD40L, interferon-gamma, interleukin (IL)-10, IL-6, and tumor necrosis factor-α. It was concluded that CD4 served a crucial role in the elimination of human cancer cells. Furthermore, the efficacies of CD40 agonist and programmed cell death protein 1 (PD1) antagonist treatments were assessed in CD4-depleted mice. CD40 agonist treatment resulted in faster cancer cell elimination and increased cytokine excretion. In conclusion, CD4 or CD40L significantly influenced cancer elimination. CD40 agonist antibodies may be potent adjuvant agents that can be used in patients with reduced CD4 or CD40L expression.

CD40 Agonist Antibodies in Cancer Immunotherapy.

CD40 is a cell-surface member of the TNF (tumor necrosis factor) receptor superfamily. Upon activation, CD40 can license dendritic cells to promote antitumor T cell activation and re-educate macrophages to destroy tumor stroma. Numerous agonist CD40 antibodies of varying formulations have been evaluated in the clinic and found to be tolerable and feasible. Administration is associated with mild to moderate (but transient) cytokine release syndrome, readily managed in the outpatient setting. Antitumor activity with or without anti-CTLA4 monoclonal antibody (mAb) therapy has been observed in patients with melanoma, and major tumor regressions have been observed in patients with pancreatic cancer, mesothelioma, and other tumors in combination with chemotherapy. In a recent study of chemotherapy plus CD40 mAb, with or without PD-1 mAb, the objective response rate in patients with untreated, metastatic pancreatic cancer was >50%. Mechanistically, the combination of chemotherapy followed by CD40 mAb functions as an in situ vaccine; in addition, destruction of stroma by CD40-activated macrophages may enhance chemotherapy delivery. Evidence to date suggests that CD40 activation is a critical and nonredundant mechanism to convert so-called cold tumors to hot ones (with prominent tumor infiltration of T cells), sensitizing them to checkpoint inhibition.

Abstract 4976: Ex vivo functional characterization and in vivo efficacy validation of human CD40 agonistic antibodies in the human CD40 knock-in model (CD40 HuGEMM)

Abstract CD40 receptor is a member of TNF-receptor superfamily, broadly expressed on the surface of antigen-presenting cells (APC) including B cells, dendritic cells (DC), macrophages, monocytes, and non-APC like platelets, endothelial cells and even some tumor cells. CD40 is essential for APC activation and signalling via ligation of CD40 ligand located on helper T cells and CD40 on APC to mediate licensing (activating) of APC. Ligation of CD40 on DCs, for example, can induce increased surface expression of costimulatory and MHC molecules, production of pro-inflammatory cytokines, and enhanced T cell activation. CD40 ligation on resting B cells can increase its antigen-presenting function and proliferation. In contrast to its critical role in the induction of effective innate and adaptive immune responses, CD40 signalling on certain malignant cells, particularly B cell lymphomas, triggers tumor apoptosis. The dual function of CD40 signalling provide unique opportunities for the use of agonistic CD40 antibodies in cancer immunotherapy. Indeed, several CD40 monoclonal antibodies are now in different stages of clinical development, some shown promising preliminary results in combination with other cancer immunotherapies. However, we are lacking preclinical models to evaluate efficacy of therapeutic CD40 agonistic antibodies, which usually don’t cross-bind to mouse targets. To fill this gap, we developed a human CD40 knock-in model (CD40 HuGEMM), of which mouse exon 2-5 are replaced by human counterparts. These KI mice express a chimeric CD40 with human extracellular domain &amp; mouse trans-membrane and intracellular sequences. We have characterized the human CD40 expression of CD40 HuGEMM on a broad spectrum of mouse cells, such as lymphocytes, macrophages, DCs, and endothelial cells. In addition, we confirmed that human CD40 antibodies bind to the chimeric m/hCD40 recombinant protein, and lead to increased expression of MHCII on the B cells. Finally, the in vivo efficacy study indicates that human CD40 antibody treatment lead to robust anti-tumor response and contribute to better survival of the mice. Taken together, our CD40 HuGEMM provides a powerful preclinical model to assess the efficacy of the human-specific CD40 agonistic antibodies. It may also serve as a model for proof of concept studies of CD40 agonistic antibodies with other therapies. Citation Format: Daniel Xianfei He, Lei Zheng, Ruilin Sun, Annie Xiaoyu An, Jian Fei, Henry Qixiang Li, Davy Xuesong Ouyang. Ex vivo functional characterization and in vivo efficacy validation of human CD40 agonistic antibodies in the human CD40 knock-in model (CD40 HuGEMM) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4976.

Abstract CT004: A Phase Ib study of CD40 agonistic monoclonal antibody APX005M together with gemcitabine (Gem) and nab-paclitaxel (NP) with or without nivolumab (Nivo) in untreated metastatic ductal pancreatic adenocarcinoma (PDAC) patients

Abstract Background: Checkpoint inhibitors such as anti-PD-1 are ineffective as single agents for patients (pts) with PDAC. Preclinical data suggest that chemotherapy with agonistic CD40 antibodies can be combined with anti-PD-1 to trigger effective T cell immunity. We conducted a multi-center, open label clinical trial to evaluate the combination of APX005M with nivo and standard chemotherapy (gem and NP). Herein, we report safety and efficacy from the ongoing study. Methods: Pts with previously untreated PDAC were enrolled in 4 cohorts: Gem/NP/APX005M 0.1 mg/kg (B1), Gem/NP/APX005M 0.3 mg/kg (B2), Gem/NP/Nivo/APX005M 0.1 mg/kg (C1) and Gem/NP/Nivo/APX005M 0.3 mg/kg (C2). Primary objectives were to evaluate safety and determine the recommended Phase II dose (RP2D) of APX005M. Secondary objectives included tumor response and immune pharmacodynamics. Analyses were performed on dose-limiting toxicity (DLT)-evaluable subjects, defined as receiving 1 dose of APX005M and ≥ 2 doses of gem/NP during Cycle 1 and remaining on study through Cycle 2 Day 1. Results: N=30 pts dosed; 24 DLT-evaluable (6 per cohort). Median follow up is 32.2 weeks. N=13 (54%) pts experienced an AE leading to discontinuation, and 10 (42%) pts experienced a treatment-related serious AE. Two DLTs were observed, 1 each in cohorts B2 and C1 (grade 3 and 4 febrile neutropenia, respectively). AE rates were similar across cohorts. Four (17%) subjects died (2 each in Cohorts B1 and C1) due to disease progression (n=2) and AE (n=2, sepsis and septic shock in the setting of neutropenia). Within the DLT-evaluable population, best overall responses included 14 (58%) PR (11 confirmed, 3 unconfirmed), 8 (33%) SD, 1 (4%) PD and 1 (4%) NE. Post-baseline tumor assessments were available for 2 of the 6 DLT-inevaluable pts (best overall responses of SD and confirmed PR). Multiplexed IHC analysis of baseline tumors revealed a low CD8 T cell and high macrophage infiltrate. Analysis of circulating mutant KRAS DNA showed marked and rapid decrease with therapy in some pts. Immune profiling of PBMCs at baseline and on-treatment by CyTOF revealed remodeling of the myeloid compartment in response to treatment, with rapid activation of dendritic cells in most pts. Conclusions: Gem/NP/APX005M ± nivo demonstrated manageable safety profiles and promising antitumor activity in untreated metastatic PDAC pts. APX005M 0.3 mg/kg was selected as the dose for a randomized Phase II study in which the primary endpoint is 1-year overall survival. Clinical trial information: NCT02482168. Citation Format: Mark H. O'Hara, Eileen M. O'Reilly, Mick Rosemarie, Gauri Varadhachary, Zev A. Wainberg, Andrew Ko, George A. Fisher, Osama Rahma, Jaclyn P. Lyman, Christopher R. Cabanski, Erica L. Carpenter, Travis Hollmann, Pier Federico Gherardini, Lacey Kitch, Cheryl Selinsky, Theresa LaVallee, Ovid C. Trifan, Ute Dugan, Vanessa M. Hubbard-Lucey, Robert H. Vonderheide. A Phase Ib study of CD40 agonistic monoclonal antibody APX005M together with gemcitabine (Gem) and nab-paclitaxel (NP) with or without nivolumab (Nivo) in untreated metastatic ductal pancreatic adenocarcinoma (PDAC) patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT004.

Abstract LB-135: Targeting the myeloid-cell specific SRC-kinase HCK improves anti-tumor immunity

Abstract Elevated expression of the myeloid cell-specific Src-family kinase HCK occurs in a majority of solid malignancies and correlates with poor patient survival [Poh et al., Frontiers Oncol 2018]. We have recently shown that genetic ablation, or therapeutic inhibition, of HCK suppresses the growth of primary tumors arising in the colon, stomach, lung and other mutagenized epithelia of mice. Mechanistically, we have attributed this to the capacity of HCK activity to support and retain the polarization of a wound-healing, Tie2+ (i.e. alternative activated) endotype of tumor-associated macrophages and concomitant tumor vascularization [Poh et al., Cancer Cell2017]. Here we extend these observations to MC38 colon cancer, B6/F10 melanoma and EO771 breast cancer allograft model, where the growth of the primary lesion and its metastatic spread is suppressed in HCK knockout hosts. More importantly, HCK gene deletion or therapeutic HCK inhibition with a small kinase inhibitor in mouse models further enhances the anti-tumor effects conferred by either chemotherapy or single agent immunotherapies based on anti-PD-L1, anti-CTLA4 or agonistic-CD40 antibodies. These observations are underpinned by increased tumour cell apoptosis that coincides with enhanced expression of ifng, gzmb, prf1 and other effector proteins in NK and infiltrating CD8+ cells. Likewise, HCK inhibition confers increased expression of il12 and ifng in tumor-associated macrophages, which adopt a more conventional activated endotype. Because HCK-deficiency of the host also associated with increased abundance of tumor infiltrating effectors cells, we propose that therapeutic targeting of HCK not only “makes tumors hotter”, but also improves host anti-tumor immunity. We are therefore developing novel HCK-specific small molecule inhibitors. Citation Format: Matthias R. Ernst, Ashwini Chand, Nicholas Huntington, Robert O'Donoghue, Ashleigh Poh. Targeting the myeloid-cell specific SRC-kinase HCK improves anti-tumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-135.

Abstract 3251: Fibroblast activation protein (FAP)-selective delivery of CD40 agonistic DARPin®molecule for tumor-localized immune activation

Abstract CD40 is a co-stimulatory molecule belonging to the tumor necrosis factor receptor superfamily which can activate both innate and adaptive immune system, making it an interesting target for tumor immunotherapy. Systemic administration of agonistic CD40 antibodies (Ab) has shown signs of activity in cancer patients, but dose-limiting toxicity impaired the clinical efficacy. New approaches are therefore needed to increase the therapeutic index of CD40-targeting molecules and achieve better clinical outcomes. Here, we report an alternative approach designed to activate CD40 specifically in the tumor microenvironment (TME), and not systemically, in order to increase efficacy and reduce systemic toxicity. This novel approach is based on a bispecific DARPin® molecule, targeting CD40 and fibroblast activation protein (FAP) alpha, intended to induce immune activation only when clustered by binding to FAP-expressing cells in the TME. The bispecific FAP x CD40 DARPin®molecule was tested in a reporter assay and in additional cell assays using primary human 1) B cells, 2) macrophages and 3) dendritic cells. These studies demonstrated CD40 activation only in the presence of FAP-positive, but not with FAP-negative cells, confirming a mechanism of action strictly dependent on FAP-mediated cross-linking. A surrogate mouse-specific FAP x CD40 DARPin® molecule (mFAP x CD40) was generated and tested in similar in vitro assays and showed FAP-dependent activation of CD40 and comparable results as the human construct. In vivo experiments, performed in tumor-free mice, showed a comparable half-life between mFAP x CD40 and an anti-mouse CD40 Ab (clone FGK45). However, mFAP x CD40, in contrast to the FGK45 Ab, did not increase the serum level of IL-6, supporting a mode of action that is dependent on FAP-mediated crosslinking of CD40 receptor. In additional studies mFAP x CD40 was active and inhibited the growth of FAP+ tumors. There were no signs of toxicity with mFAP x CD40 in contrast to the FGK45 Ab which resulted in body weight loss. In conclusion, we have generated bispecific agonist FAP x CD40 DARPin® molecules able to activate the CD40 pathway with a targeting (FAP)-dependent mechanism of action. Citation Format: Nicolo Rigamonti, Anja Schlegel, Sophie Barsin, Jonas Schwestermann, Susanne Mangold, Yvonne Kaufmann, Christof Zitt, Niina Veitonmäki, Victor Levitsky, Clara Metz. Fibroblast activation protein (FAP)-selective delivery of CD40 agonistic DARPin®molecule for tumor-localized immune activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3251.

Abstract CT089: Phase Ib/II of CD40 agonistic antibody APX005M in combination with nivolumab (nivo) in subjects with metastatic melanoma (M) or non-small cell lung cancer (NSCLC)

Abstract Background: Despite recent success with checkpoint inhibitors, the majority of patients with M or NSCLC have a transient response or no response to checkpoint blockade. Preclinical data suggest that activation of CD40 can be combined with PD-1 blockade to trigger effective T cell immunity. We are conducting a multi-center, open label Phase Ib/II clinical trial to evaluate the combination of APX005M with nivo in subjects with M or NSCLC. We report safety and efficacy from the completed Phase Ib portion of the study and the 1st stage of the Phase II M cohort. Methods: Phase Ib followed a 3+3 design and enrolled adult subjects with M and disease progression (PD) while receiving anti-PD-1 therapy (anti-CTLA-4 more than 3 months prior to study entry was allowed) and subjects with immunotherapy naïve NSCLC, in 3 dose levels of APX005M (0.03, 0.1 and 0.3 mg/kg) combined with a fixed dose of nivo (360mg) every 3 weeks. Primary objectives in Phase Ib were to evaluate safety and determine the Phase II dose (P2D) of APX005M. Phase II is enrolling subjects with M or NSCLC in two parallel Phase II cohorts, each following a Simon 2-stage design. Primary objective in Phase II is to evaluate the tumor response in each cohort. Phase Ib analyses were performed on dose limiting toxicity (DLT)-evaluable subjects. Phase II analyses were performed on all treated subjects. Results: Phase Ib: No DLTs were observed in the 9 subjects enrolled in Phase Ib and the P2D for APX005M is 0.3 mg/kg. Four subjects experienced Grade 3 AEs considered related to study drugs (non-DLTs, including transaminitis, hyperbilirubinemia, anemia, pneumonitis, 1 subject each) with no grade 4 AEs reported. Of the 5 subjects with M, 1 had a confirmed PR, 2 had prolonged SD (&amp;gt;8 months) and 2 had PD as best overall response. Of the 4 subjects with NSCLC, 1 had a robust confirmed PR, 2 had SD (on study lesion biopsies histology negative) and 1 had PD as best overall response. Phase II: The 1st stage of the M cohort enrolled 10 additional subjects. One subject experienced a Grade 3 AE considered related to study drugs with no grade 4 AEs reported. Of these 10 subjects, 2 had confirmed PR, 2 had SD, and 6 had PD as best overall response. The overall toxicity profile of the combination is consistent with the profiles of individual agents. NanoString analysis of paired tumor biopsies revealed high tumor-infiltrating lymphocytes, and increased expression of IFNγ inducible cytokines (CXCL9 and CXCL10) while on treatment. Increased tumor T cell infiltration was further confirmed by immunohistochemistry. Conclusions: APX005M + nivo demonstrated a good safety profile and promising antitumor activity in M subjects with PD while receiving anti-PD-1 therapy and potential activity in NSCLC. The study is currently enrolling subjects in the 2nd stage of the Phase II M cohort and the 1st stage of the Phase II NSCLC cohort. Clinical trial information: NCT03123783. Citation Format: Harriet Kluger, Sarah A. Weiss, Anthony J. Olszanski, Lynn Schuchter, Gerald P. Linette, Linda Garland, Nicholas O. Iannotti, Melissa Johnson, Emin Avsar, Minu K. Srivastava, Ovid C. Trifan, Martin J. Edelman. Phase Ib/II of CD40 agonistic antibody APX005M in combination with nivolumab (nivo) in subjects with metastatic melanoma (M) or non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT089.

A phase I study to assess safety, pharmacokinetics (PK), and pharmacodynamics (PD) of JNJ-64457107, a CD40 agonistic monoclonal antibody, in patients (pts) with advanced solid tumors.

2527 Background: JNJ-64457107 (JNJ-107) is an agonistic human monoclonal (IgG1) antibody targeting CD40, a novel target for anti-tumor immunotherapy with a central role in adaptive and innate immunity. Methods: JNJ-107 was administered intravenously Q2W in treatment cycles of 28 days. Dose escalation was pursued with (w) and without (wo) pre-infusion steroids for mitigation of infusion related reactions (IRRs). Dose-limiting toxicity (DLT), safety, PK, PD and antitumor activity were evaluated. Results: 95 pts of age 18-80 years (median 59) were enrolled in 7 cohorts (n = 50, 75µg/kg – 2000 µg/kg) w/steroids and 5 cohorts (n = 45, 75 µg/kg – 1200 µg/kg) wo/steroids and received 1-26 (median 3) cycles of JNJ-107. Two DLTs occurred: Grade (G) 3 headache lasting 5 days at 1200 µg/kg w/steroids and G3 ALT/AST + G2 bilirubin increase at 1200 µg/kg wo/steroids. Most frequent adverse events (≥20%) were pyrexia (41%), fatigue (39%), pruritus (39%), headache (26%), chills (26%), nausea (22%) and rash (21%). IRRs were reported in 51% of pts (G1-G2 50%, G3 1%). Most commonly reported IRRs (≥10%) were pruritus (31%), rash (15%), chills (13%) and flushing (12%). Cetirizine and Montelukast premedication during dose escalation wo/steroids significantly reduced IRRs. Preliminary PK of JNJ-107 suggest target mediated drug disposition with rapid decline in serum concentrations (half-life of ~13h at 600 µg/kg and ~ 24h at doses ≥1200 µg/kg). Dose proportional increase in Cmax and AUC(last) was observed at doses ≥1200 µg/kg and more than dose proportional increase was seen at lower doses. PD of JNJ-107 demonstrated dose-independent reduction in peripheral blood B cells recovering in a dose-dependent manner. MCP-1, IP-10, MIP-1a, and MIP-1b cytokines showed high-level responses with cytokine/chemokine secretion kinetics consistent, but not confirmatory, for activation of antigen presenting cells. IFNg, TNF, and IL-8 showed moderate responses reflecting downstream T cell activation. Other tested cytokines were at low levels. A partial response lasting 9.2 months was observed in 1 pt with renal cell cancer. 13 (14%) and 10 (11%) pts showed stable disease lasting ≥3 months and ≥ 6 months, respectively. Conclusions: The CD40 agonist JNJ-107 has a manageable safety profile with favorable PK and PD properties. Future clinical development will require combination with either chemotherapy, or other immunotherapies such as antitumor vaccines or checkpoint inhibitors. Clinical trial information: NCT02829099.

Localizing radioimmunotherapy via nanochannel device for sustained intratumoral drug delivery for solid tumor treatment.

37 Background: Immune related adverse events still occur in up to 91% of patients receiving immunotherapy. Intratumoral administration is a potential solution to limit these events by reducing systemic exposure while increasing local concentration. However, intratumoral injection is hindered by rapid clearance of drug from the tumor. Our group has developed an intratumoral nanochannel implant for sustained delivery of immunotherapy (NDES) as a solution. Recent clinical and preclinical studies have found success in the combination of radiotherapy and immunotherapy in improving both local and distant tumor response. We propose a combination of radiotherapy followed by sustained intratumoral delivery of immunotherapy as a treatment regimen to improve tumor response and reduce side effects. Methods: Mice were implanted with the 4T1 murine mammary carcinoma and separated into treatment and control groups. CD40 agonist antibody was delivered intratumorally via NDES. Radiotherapy was administered at 8 Gy for three consecutive days and implantation of the NDES occurred the day after the final fraction of radiation. The tumor growth curve was plotted and tumor, spleen, lymph nodes, lungs, and blood were collected at the study endpoint for further flow cytometry and histological analysis. Results: The combination of radiotherapy and sustained intratumoral CD40 antibody showed significantly decreased tumor growth rates over radiotherapy or sustained intratumoral immunotherapy alone. Both intratumoral and systemic T-cell activation was observed. Mice treated with sustained intratumoral CD40 antibody showed decreased toxicity when compared to those receiving comparable systemic dosage. Conclusions: Radiotherapy combined with local sustained intratumoral immunotherapy is a potential strategy for improving treatment of solid tumors which currently show suboptimal response to current immunotherapy regimens and for inducing a systemic response to distant metastases while minimizing adverse side effects. The sustained delivery profile of the NDES presents an opportunity for practical intratumoral administration and avoidance of repeated invasive procedures in patients.

A CD40 Agonist and PD-1 Antagonist Antibody Reprogram the Microenvironment of Nonimmunogenic Tumors to Allow T-cell–Mediated Anticancer Activity

In cancers with tumor-infiltrating lymphocytes (TILs), monoclonal antibodies (mAbs) that block immune checkpoints such as CTLA-4 and PD-1/PD-L1 promote antitumor T-cell immunity. Unfortunately, most cancers fail to respond to single-agent immunotherapies. T regulatory cells, myeloid derived suppressor cells (MDSCs), and extensive stromal networks within the tumor microenvironment (TME) dampen antitumor immune responses by preventing T-cell infiltration and/or activation. Few studies have explored combinations of immune-checkpoint antibodies that target multiple suppressive cell populations within the TME, and fewer have studied the combinations of both agonist and antagonist mAbs on changes within the TME. Here, we test the hypothesis that combining a T-cell-inducing vaccine with both a PD-1 antagonist and CD40 agonist mAbs (triple therapy) will induce T-cell priming and TIL activation in mouse models of nonimmunogenic solid malignancies. In an orthotopic breast cancer model and both subcutaneous and metastatic pancreatic cancer mouse models, only triple therapy was able to eradicate most tumors. The survival benefit was accompanied by significant tumor infiltration of IFNγ-, Granzyme B-, and TNFα-secreting effector T cells. Further characterization of immune populations was carried out by high-dimensional flow-cytometric clustering analysis and visualized by t-distributed stochastic neighbor embedding (t-SNE). Triple therapy also resulted in increased infiltration of dendritic cells, maturation of antigen-presenting cells, and a significant decrease in granulocytic MDSCs. These studies reveal that combination CD40 agonist and PD-1 antagonist mAbs reprogram immune resistant tumors in favor of antitumor immunity.

Abstract A159: Agonistic CD40 antibody therapy induces formation of tertiary lymphoid structures in glioma and inhibits the response to immune-checkpoint blockade

Abstract Cancer immunotherapy of glioma, the most common primary brain tumor in adults, is constrained by an immunosuppressive microenvironment. Tertiary lymphoid structures (TLSs) are ectopic lymphoid structures that mediate immune responses and provide a local site for tumor antigen presentation. Here, we show for the first time that TLSs are present in human low-grade glioma and that they can be induced in murine glioma models. Agonistic CD40 antibodies induced lymphotoxin α expression in B cells and enhanced the formation of TLSs in mice bearing orthotopic GL261 or CT-2A gliomas. TLSs consisting of B cells, T-cells and antigen presenting cells formed around CD31+ vessels proximal to the tumor tissue and adjacent to the meninges. Agonistic CD40 antibody treatment improved the CD8+ T-cell / Treg ratio in tumor-bearing mice, but there was no survival benefit. A decreased CD69 activation status on CD8+ T-cells, an increase of B cells with a CD1d+CD5+ regulatory phenotype and a high infiltration of Tregs in TLSs indicate that agonistic CD40 antibodies induce an immunosuppressive microenvironment in glioma. Consistent with this, the efficacy of both PD-1 and CTLA-4 checkpoint blockade was significantly decreased by co-administration of agonistic CD40 antibodies. These results demonstrate that TLSs are present and can be induced in glioma, but that they at least under certain conditions are associated with immunosuppression, shedding light on new mechanisms of immune regulation in the brain microenvironment. Citation Format: Luuk van Hooren, Alessandra Vaccaro, Maria Georganaki, Mohanraj Ramachandran, Hua Huang, Joey Lau, Anja Smits, Magnus Essand, Anna Dimberg. Agonistic CD40 antibody therapy induces formation of tertiary lymphoid structures in glioma and inhibits the response to immune-checkpoint blockade [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A159.

The Regulatory Status Adopted by Lymph Node Dendritic Cells and T Cells During Healthy Aging Is Maintained During Cancer and May Contribute to Reduced Responses to Immunotherapy.

Aging is associated with an increased incidence of cancer. One contributing factor could be modulation of immune cells responsible for anti-tumor responses, such as dendritic cells (DCs) and T cells. These immunological changes may also impact the efficacy of cancer immunotherapies in the elderly. The effects of healthy aging on DCs and T cells, and their impact on anti-mesothelioma immune responses, had not been reported. This study examined DCs and T cells in young (2–5 months; equivalent to 16–26 human years) and elderly (20–24 months; equivalent to 60–70 human years) healthy and mesothelioma-bearing C57BL/6J mice. During healthy aging, elderly lymph nodes adopted a regulatory profile, characterized by: (i) increased plasmacytoid DCs, (ii) increased expression of the adenosine-producing enzyme CD73 on CD11c+ cells, and (iii) increased expression of multiple regulatory markers (including CD73, the adenosine A2B receptor, CTLA-4, PD-1, ICOS, LAG-3, and IL-10) on CD8+ and CD4+ T cells, compared to lymph nodes from young mice. Although mesotheliomas grew faster in elderly mice, the increased regulatory status observed in healthy elderly lymph node DCs and T cells was not further exacerbated. However, elderly tumor-bearing mice demonstrated reduced MHC-I, MHC-II and CD80 on CD11c+ cells, and decreased IFN-γ by CD8+ and CD4+ T cells within tumors, compared to young counterparts, implying loss of function. An agonist CD40 antibody based immunotherapy was less efficient at promoting tumor regression in elderly mice, which may be due to: (i) failure of elderly CD8+ T cells to up-regulate perforin, and (ii) increased expression of multiple regulatory markers on CD11c+ cells and T cells in elderly tumor-draining lymph nodes (including CD73, PD-1, ICOS, LAG-3, and TGF-β). Our findings suggest that checkpoint blockade may improve responses to immunotherapy in elderly hosts with mesothelioma, and warrants further investigation.