ALBERT

Beschreibung: Background: MOR202, a human anti-CD38 monoclonal antibody, is currently being evaluated in a phase I/IIa clinical trial for the treatment of multiple myeloma (MM). Pharmacodynamically, MOR202 exerts its tumoricidal effect by eliciting antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). Aside from a promising single-agent activity profile, experiments in vitro indicate additive or synergistic effects of MOR202 in combination with different types of standard of care compounds in MM such as lenalidomide (LEN) or bortezomib (BOR). Aims: To compare in vitro the ADCC profile of MOR202 on MM cells and normal hematopoietic cellswith the respective profiles of two other anti-CD38 antibodies in clinical development: daratumumab and isatuximab. To determine the tumoricidal efficacy of MOR202 in vivo in combination with either LEN, BOR or melphalan (MEL), representing immunomodulatory drugs (IMiDs), proteasome inhibitors, and alkylating agents, respectively. Method: The in vitro ADCC profile of the antibodies was assessed by fluorescence activated cell sorting using a panel of CD38+ MM cell lines in the presence of peripheral blood mononuclear cells. The potential for cytotoxicity towards normal hematopoietic cells was tested on purified natural killer (NK) cells by measuring NK-NK killing. In the in vivo studies, two independent mouse models were employed to assess combinatorial effects. Firstly, as a model for MM, NCI-H929 cells were inoculated intratibially into the bone marrow to establish an orthotopic model characterized by prototypical hallmarks of the disease, such as bone lysis, and the emergence of serum M protein. Bone density, evaluated by microcomputed tomography (μCT), and M protein serum levels were used as endpoint analyses for treatment efficacy. Secondly, as a model for disseminated lymphoma, Ramos non-Hodgkin lymphoma cells were intravenously injected into immunodeficient mice. Survival served as the primary endpoint, reflecting the success of medication. Combinatorial drug interactions were evaluated according to Clarke, 1997 (Breast Cancer Res Treat; 46:255-78) and Chou, 2006 (Pharmacol Rev; 58:621-81). Results: In the in vitro ADCC studies on MM cell lines, the maximum killing of MOR202 was equivalent to the tested comparator antibodies. In contrast, the potential to induce killing of normal NK cells expressing low levels of CD38 was significantly reduced for MOR202 compared with daratumumab and isatuximab (n=6 donors; median of 7% specific killing vs 30% and 37%, respectively). This appeared to be independent of FcγRIIIa receptor polymorphism status. In the mouse MM model, MOR202 administration at 3 mg/kg significantly reduced bone lysis by up to 72.5%, relative to vehicle control. Treatment with LEN, BOR, or MEL alone also decreased bone lysis significantly, as compared with vehicle control. However, coadministration of MOR202 with LEN, BOR, or MEL completely abolished or dramatically reduced bone lysis (Figure). Drug interaction analyses indicated synergistic efficacy. The markedly reduced bone lysis seen with combination therapy was accompanied by a reduction (〉90%) of serum M protein levels indicating a significant decrease in tumor load (Figure). In the disseminated lymphoma model, LEN or BOR administration had no impact on survival time as compared with vehicle control. In contrast, MOR202 treatment resulted in significantly improved survival compared with vehicle control (median 20 and 20.5 days vs 42 and 43.5 days, respectively, in two independent experiments). Notably, coadministration of MOR202/LEN, or MOR202/BOR further improved survival, indicating potentiation of MOR202 activity by agents which by themselves had little effect (i.e., a subtype of synergy). Of note, all mice receiving monotherapy finally succumbed to the tumor. In contrast, 37.5% of mice treated with MOR202/LEN and 40% of mice treated with MOR202/BOR were completely free of tumor until study termination at day 98. Conclusions: MOR202 shows equivalent ADCC to CD38 high expressing MM cells as compared with daratumumab and isatuximab, while provoking significantly reduced off-tumor killing of CD38 low expressing normal NK cells. In addition, MOR202 acts synergistically in vivo in combination with different compounds representative of classes of agents commonly used in the treatment of hematologic malignancies. Figure 1. Figure 1. Disclosures Boxhammer: MorphoSys AG: Employment. Weirather:MorphoSys AG: Employment. Steidl:MorphoSys AG: Employment. Endell:MorphoSys AG: Employment.

Beschreibung: Background: MOR202 is a fully human anti-CD38 antibody currently being tested in a Phase I/IIa clinical trial in multiple myeloma (MM). It mediates antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in MM cells with high potency (EC50 ~200 pM) representing a possible promising new therapy for MM patients. In this in vitro study, we evaluated the synergistic potential of MOR202 and pomalidomide (POM), a newly approved IMiD® immunomodulatory agent in MM therapy. Methods: Using flow cytometry analysis, POM was evaluated in relation to its effects on several parameters anticipated to be relevant for anti-tumor activity when combined with MOR202. This included the induction of direct cytotoxicity and CD38 upregulation in several MM cell lines, as well as the activation of human immune effector cells derived from peripheral blood mononuclear cells of healthy donors. On a functional level the interaction of MOR202 and POM was assessed using FACS-based ADCC assays. Different incubation schemes prior to the ADCC assays were evaluated in order to distinguish the influence of POM on ADCC activity when pre-incubated for 72 hours either on target or effector cells or on both in parallel. The observed combination effects were analyzed for synergistic potential. Experiments were carried out in triplicate and mean values (±SEM) were calculated. Results: POM as a single agent showed cytotoxic effects on MM cell lines with high potency (EC50 ~150 nM) and additionally induced an up to 2.7-fold upregulation of CD38 (EC50 ~20 nM) on CD38-expressing MM cell lines. Both effects were maximal at the last tested time point of 72 hours and strongest on cell lines with comparably lower CD38 expression levels. In combination with the observed activation of effector cells these POM-mediated mechanisms lead to a synergistically enhanced cytotoxic activity of MOR202. This synergistic benefit ranged between 1.2-fold and 3.1-fold above theoretical additivity depending on the cell line used and was most pronounced in the case of strong CD38 upregulation. Figure 1 Exemplary ADCC dose-response curves for the comparably lower CD38 expressing cell line AMO-1 after POM pre-treatment of effector cells, target cells or both. Figure 1. Exemplary ADCC dose-response curves for the comparably lower CD38 expressing cell line AMO-1 after POM pre-treatment of effector cells, target cells or both. Conclusions: The cytotoxic activity of MOR202 on MM cells was enhanced and synergized when combined with the immunomodulator agent POM via multiple mechanisms, namely direct cytotoxicity, CD38 upregulation and activation of effector cells. These results provide a mechanistic rationale for combining MOR202 and POM and warrant further evaluation in the clinical setting. Disclosures Endell: MorphoSys AG: Employment, Patents & Royalties. Boxhammer:Morphosys AG: Employment, Patents & Royalties. Steidl:MorphoSys AG: Employment, Patents & Royalties.

Beschreibung: Introduction Tafasitamab (MOR208) is an Fc-enhanced, humanized, monoclonal antibody that binds to the human B cell surface antigen CD19. CD19 is broadly and homogeneously expressed across different B cell malignancies, including diffuse large B cell lymphoma (DLBCL), and amplifies B cell receptor signaling and induces tumor cell proliferation. Tafasitamab is currently in clinical development in patients with relapsed or refractory DLBCL in combination with the immunomodulatory drug lenalidomide (L-MIND study) and the chemotherapeutic agent bendamustine (B-MIND study). The modes of action of tafasitamab comprise antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and direct cytotoxicity (apoptosis). Tafasitamab carries two amino acid exchanges in the Fc region to increase its affinity to Fcγ receptors, including FcγRIIIa. FcγRIIIa plays a key role in mediating ADCC and is expressed on the surface of natural killer (NK) cells, as well as the majority of γδ T cells. MG4101 (a novel therapeutic agent consisting of cryopreserved, ex vivo-expanded, highly activated NK cells) has demonstrated potent anticancer activity in preclinical in vitro and in vivo studies. Currently, MG4101 is in clinical development in patients with malignant lymphoma and advanced solid tumors. Here, we have characterized two FcγRIIIa receptor-expressing cell types, γδ T cells and NK cells (MG4101), as effector cells for tafasitamab in vitro and explored the concept of supplementing MG4101 during tafasitamab therapy using disseminated in vivo models of non-Hodgkin's lymphoma. Methods γδ T cells (CD3+/γδ T cell receptor+) were derived from different donors by stimulation of peripheral blood mononuclear cells with zoledronate/IL-2 for 9-10 days. These were applied as effector cells in in vitro ADCC assays with tafasitamab in Mino and Jeko-1 mantle cell lymphoma (MCL) cell lines, as well as primary patient-derived chronic lymphocytic lymphoma (CLL) and MCL cells. Further, effector cell activity of MG4101 was assessed using tafasitamab-mediated ADCC assays in Raji and Ramos Burkitt's lymphoma cells. The concept of combining tafasitamab with allogeneic effector cell therapy in vivo was studied in two therapeutic survival models of disseminated lymphoma in SCID mice. In the Raji model, tafasitamab (0.05 µg/mouse) was given on Day 1 after intravenous (IV) tumor inoculation, while MG4101 (2x107 cells/mouse) was given on Days 1, 3, 6, 8 and 10. In the Ramos model, tafasitamab (10 mg/kg) and MG4101 (2x107 cells/mouse) were applied twice weekly for 3 weeks starting on Days 3 and 4, respectively, after IV tumor inoculation. Results Tafasitamab in combination with γδ T cells showed distinctly increased ADCC in Mino and Jeko-1 target cells in vitro, compared with a negative control IgG1 antibody. ADCC assays with patient-derived CLL and MCL target cells confirmed tafasitamab-mediated cytotoxic activity and demonstrated a clear enhancement in activity compared with the non-Fc-enhanced version of tafasitamab that was unable to induce substantial cytotoxicity. In vitro ADCC assays with tafasitamab and MG4101 on Raji and Ramos cell lines confirmed potent effector cell activity of the ex vivo-expanded, cryopreserved, allogeneic NK cells. In the disseminated Raji survival model, combination therapy with a single low dose of tafasitamab (0.05 µg) and MG4101 resulted in a distinct increase in survival of the mice with an increased life span (ILS) of 100% compared with monotherapy (ILS of 57% for tafasitamab and 50% for MG4101). Of note, the combination demonstrated a substantial and more than additive enhancement in survival in the more therapeutic Ramos survival model (Figure 1). Combination therapy with tafasitamab (10 mg/kg) and MG4101 NK cells resulted in superior antitumor activity (ILS of 103%) compared with either tafasitamab monotherapy (ILS of 49%) or MG4101 alone (ILS of 25%). Conclusions FcγRIIIa-expressing immune cell types, including NK cells and γδ T cells, are potent effector cells for tafasitamab-mediated ADCC. Combination therapy with tafasitamab and allogeneic MG4101 NK cells in vivo demonstrated a more than additive survival benefit compared with tafasitamab or MG4101 monotherapy in a disseminated therapeutic lymphoma model. Combination of tafasitamab supplemented with immune effector cells could represent a promising new approach for lymphoma therapy. Disclosures Her: GC LabCell: Employment, Patents & Royalties. Cho:GC LabCell: Employment, Patents & Royalties. Hwang:GC LabCell: Employment, Equity Ownership, Patents & Royalties. Boxhammer:MorphoSys AG: Employment, Patents & Royalties. Steidl:MorphoSys AG: Employment. Patra:MorphoSys AG: Employment. Schanzer:MorphoSys AG: Employment. Endell:MorphoSys AG: Employment, Patents & Royalties.

Beschreibung: Abstract 4018 Background: MOR202, a HuCAL-derived fully human anti-CD38 antibody has proven to be highly effective in preclinical models of multiple myeloma (MM) and is currently evaluated in a phase I/II clinical trial. Having previously identified ADCC as potent effector mechanism of MOR202, the capability to induce killing of MM patient cells via antibody dependent cellular phagocytosis (ADCP) was assessed. Furthermore, the immunomodulatory agent lenalidomide (LEN), a commonly used agent in MM therapy was investigated for its potential to enhance the cytotoxicity of MOR202 in vitro and in vivo. Methods: Drug effects in presence or absence of LEN were characterized in vitro in a FACS-based phagocytosis assay using macrophages derived from M-CSF stimulated monocytes and a panel of CD38+ MM target cells. The therapeutic potential of MOR202 in vivo as a single agent and in combination with LEN was studied in a disseminated survival model of iv injected Ramos lymphoma cells. Synergy was determined using the fractional product concept. Results: MOR202 induced ADCP with high potency showing EC50 values between 40 and 130pM. Maximal killing was donor and cell line dependent ranging from 11 to 72%. The combination with LEN induced additive to synergistic enhancement of MOR202 activity which was mediated by several mechanisms identified to be direct cytotoxicity and increased CD38 expression levels on MM cells. In vivo, MOR202 at 1mg/kg increased median survival (MS) by 142% compared to vehicle control (MS day 48.5 vs. day 20), while LEN had no distinct effect at any of the tested doses between 25 and 100mg/kg (MS day 21–22). Intriguingly, despite the apparent lack of efficacy by LEN alone co-administration of 1mg/kg MOR202 and 100mg/kg LEN resulted in a superior increase of MS by 225% (MS day 65), thus demonstrating strong synergism. Of note, while no mouse survived beyond day 65 in any other group, 3/8 animals in the combo group were completely free of tumor until study termination on day 98. Conclusions: We here demonstrate ADCP to be an additional potent effector mechanism of MOR202. The combination of MOR202 and LEN enhanced ADCP-mediated killing in vitro and increased median survival in vivo in a synergistic manner. These results suggest a mechanistic rationale for MOR202 combinations with LEN including in particular LEN non-responders or relapse/refractory patients, thus warranting further evaluation in future clinical trials. Disclosures: Endell: MorphoSys AG: Employment. Boxhammer:MorphoSys AG: Employment. Wurzenberger:MorphoSys AG: Employment. Ness:MorphoSys AG: Employment. Steidl:MorphoSys AG: Employment.