Bispecific T-cell Engager Antibody Research Articles

A Phase 1 First-in-Human Study of AMG 330, an Anti-CD33 Bispecific T-Cell Engager (BiTE®) Antibody Construct, in Relapsed/Refractory Acute Myeloid Leukemia (R/R AML)

A Phase 1 First-in-Human Study of AMG 330, an Anti-CD33 Bispecific T-Cell Engager (BiTE®) Antibody Construct, in Relapsed/Refractory Acute Myeloid Leukemia (R/R AML)

Open-Label, Phase 2 Study of Blinatumomab As Second Salvage Therapy in Adults with Relapsed/Refractory Aggressive B-Cell Non-Hodgkin Lymphoma

Background: Autologous hematopoietic stem cell transplantation (autoHSCT) following response to salvage chemotherapy is the standard of care for patients with relapsed/refractory (r/r) aggressive B-cell lymphoma after first-line chemotherapy. Patients without complete metabolic response (CMR) to first salvage (S1) therapy have limited options and poor outcomes based on historical data. Blinatumomab, a bispecific T-cell engager (BiTE®) antibody construct that directs cytotoxic T cells to lyse B cells expressing CD19, has demonstrated a survival benefit in B-cell acute lymphoblastic leukemia and has antitumor activity in patients with r/r aggressive B-cell non-Hodgkin lymphoma (B-NHL), including patients previously treated with autoHSCT. This open-label, multicenter, phase 2 portion of an adaptive phase 2/3 study (ClinicalTrials.gov, NCT02910063) assessed the efficacy and safety of blinatumomab as a second salvage (S2) therapy for patients with aggressive r/r NHL who have not achieved CMR following platinum-based S1 chemotherapy.Methods: Patients ≥18 years had biopsy-confirmed r/r aggressive B-NHL without a prior complete remission or CMR after first-line treatment with an anthracycline and anti-CD20 agent, and had either progressive metabolic disease (PMD), no metabolic response (NMR), or partial metabolic response (PMR; Lugano Classification) after ≥2 cycles of platinum-based S1 therapy. Patients with prior radiotherapy were PET+ ≥6 weeks after the last dose. Blinatumomab was given by continuous intravenous infusion for a single 70-day cycle 1 (9 μg/day for 7 days, 28 μg/day for 7 days, and 112 μg/day for 42 days, followed by a 14-day treatment-free interval) and an optional 28-day cycle 2 (9 μg/day for 7 days, 28 μg/day for 7 days, and 112 μg/day for 14 days). The primary endpoint was CMR by central PET. Additional endpoints were objective response rate (ORR [CMR + PMR]), post-response HSCT realization rates, and the incidence/severity of adverse events (AEs).Results: Of the 41 patients enrolled, most had PMD/progressive disease (66%) and had refractory (68%) or relapsed (32%) disease; 5 (12%) had NMR, and 9 (22%) had PMR (Table). All 41 patients received blinatumomab; 19 (46%) completed cycle 1 (Table). Twenty-two patients discontinued cycle 1 (disease progression, n=17; AE n=4; death, n=1). Among the 17 patients who discontinued cycle 1 due to disease progression, 8 (47%) completed at least 90% of planned treatment duration. Four patients started cycle 2; 3 (7%) completed cycle 2. One patient discontinued cycle 2 due to AEs. The ORR (within 12 weeks of starting blinatumomab) was 37% (15/41 patients; 95% CI, 22%, 53%); 9 (22%) patients achieved CMR (Table). Eight (20%) patients had HSCT in remission, 7 (17%) with autoHSCT (CMR, n=6; PMR, n=1), and 1 with allogeneic HSCT in PMR. Thirty-five patients did not have HSCT (n=32) or had delayed HSCT (n=3) due to PMD (n=17), lack of CMR (n=4), AE (n=4), patient preference (n=1), NMR or unknown (n=1), and other (n=8); 1 patient had missing information. Eight of 9 CMR patients (89%) were alive without relapse, with a median follow up time of 8.8 months. The Kaplan-Meier estimate at 9 months was 51%; median overall survival (OS) was not reached (Table).In total, 24 (59%) patients had grade ≥3 treatment-emergent AEs, and 10 (24%) had grade ≥4 treatment-emergent AEs. Seven (17%) patients discontinued treatment due to AEs. Consistent with previous blinatumomab reports, neurologic events (NEs) were reported in 23 (56%) patients, including 10 (24%) with grade 3 NEs and 3 (7%) with NEs leading to treatment discontinuation. Grade 3 cytokine release syndrome was reported in only 1 patient. Other grade ≥3 AEs included infections (n=8; 20%), bone marrow toxicity (n=7; 17%), thromboembolic events (n=3; 7%), hepatic disorders (n=2; 5%), and acute pancreatitis (n=1; 2%).Conclusions: In patients with r/r aggressive B-NHL and predominantly progressive disease following ≥2 cycles of platinum-based S1 chemotherapy, blinatumomab monotherapy as S2 therapy induced CMR/PMR in 37% of patients and led to HSCT in 20%. When considering that 66% of the patients enrolled had progressive disease and that 47% received the therapeutic dose, blinatumomab showed promising efficacy consistent with the efficacy and safety demonstrated in earlier blinatumomab B-NHL trials and potentially offers a treatment option for patients unresponsive to standard salvage regimens. [Display omitted] DisclosuresCoyle:Amgen Inc.: Other: non-financial relationship. Morley:Amgen Inc.: Honoraria, Other: non-financial; Roche: Honoraria, Other: non-financial, Research Funding. Rambaldi:Celgene: Consultancy; Roche: Consultancy; Omeros: Consultancy; Italfarmaco: Consultancy; Novartis: Consultancy; Amgen Inc.: Consultancy; Pfizer: Consultancy. Zhang:Amgen Inc.: Employment, Equity Ownership. Jung:Amgen Inc.: Employment, Equity Ownership. Franklin:Amgen Inc.: Employment, Equity Ownership.

Finding the Gaps: Perceived and Unperceived Needs in Malignant Hematology Training in Canadian Hematology Residents

BackgroundMalignant Hematology is in a new era of exciting novel treatment regimens and modalities, including CAR-T (Chimeric Antigen Receptor T-cells) and BiTE (Bi-specific T-cell Engaging) antibodies. Current trainees require an ever-increasing knowledge and skillset to deliver high quality care to more complex patients. There is limited evidence on the educational needs of hematology residents with these emerging complexities. Moreover, these educational needs themselves are poorly-defined. As a first step, we sought to perform a detailed needs assessment to identify knowledge gaps in our learners. It is our intention to use this information to aid in developing a curriculum incorporating these novel elements.MethodsEvery year Hematology residents in Canada (Post Graduate Year [PGY] 4 and above) attend the National Hematology Retreat in Toronto, Ontario for a weekend of educational activities, which also serves as preparation for the Royal College of Physicians and Surgeons Hematology certification exam. This past year, residents were invited to participate in a questionnaire to identify perceived and unperceived needs. They were asked to select topics of perceived needs from a pre-selected list. This was followed by a knowledge assessment using case-based questions in leukemia, myeloma, lymphoma, and Blood and Marrow Transplantation [BMT]. The study is approved by the University of Toronto Research Ethics Board. Data were analyzed descriptively as needed. Mean total scores from the case-based questions were compared between post-graduate years using one way ANOVA. All statistical calculations were performed using SPSS version 24.Results35 of 70 Canadian Hematology residents attending the retreat responded to our survey. Among the respondents, seven were PGY-4, nine were PGY-5, and 19 were PGY-6.Of our pre-selected topics list, residents perceived the most common knowledge gaps existed in management of BMT complications, followed by molecular testing (especially genomics), and novel immune and cellular therapies. The top choices differed in the PGY-4 year (BMT complications, novel immune and cellular therapies and emergency AML complications, Figure 1).Among the respondents answering case-based questions, there was a significant difference in mean scores with increasing length of training (PGY-4: 53%, PGY-5: 70%, PGY-6: 79%, p=0.009). There was a knowledge gap in BMT among all levels of residents, which correlated with their perceived knowledge gaps. However, a majority of them correctly answered the questions on molecular testing and novel immune and cellular therapies.ConclusionsNeeds assessments are useful in assessing background knowledge and identifying perceived and unperceived needs of trainees. These can be used towards creating a resource that accounts for learning priorities. Our needs assessment of hematology residents across Canada demonstrated that:•Knowledge gaps exist among residents at different levels of training, particularly in BMT, compared to other areas of Malignant Hematology. Moreover, this was perceived by residents themselves.•Learning priorities of residents may change over the course of their training.•Educational curricula should incorporate recent advances in hematology (molecular testing and novel immune and cellular therapies); however more emphasis should also be placed on BMT in general. DisclosuresNo relevant conflicts of interest to declare.

Phase 2 Study of Blinatumomab in Japanese Adults with Relapsed/Refractory Acute Lymphoblastic Leukemia (R/R ALL)

Phase 2 Study of Blinatumomab in Japanese Adults with Relapsed/Refractory Acute Lymphoblastic Leukemia (R/R ALL)

Phase II Study of Blinatumomab in Patients with B-Cell Lineage Acute Lymphocytic Leukemia with Positive Minimal/Measurable Residual Disease

Phase II Study of Blinatumomab in Patients with B-Cell Lineage Acute Lymphocytic Leukemia with Positive Minimal/Measurable Residual Disease

A gB/CD3 bispecific BiTE antibody construct for targeting Human Cytomegalovirus-infected cells

Bispecific T cell engager (BiTE) antibody constructs are successfully used as cancer therapeutics. We hypothesized that this treatment strategy could also be applicable for therapy of human cytomegalovirus (HCMV) infection, since HCMV-encoded proteins are abundantly expressed on the surface of infected cells. Here we show that a BiTE antibody construct directed against HCMV glycoprotein B (gB) and CD3 efficiently triggers T cells to secrete IFN-γ and TNF upon co-culture with fibroblasts infected with HCMV strain AD169, Towne or Toledo. Titration of gB expression levels in non-infected cells confirmed that already low levels of gB are sufficient for efficient triggering of T cells in presence of the BiTE antibody construct. Comparison of redirecting T cells with the bispecific antibody versus a chimeric antigen receptor (CAR) based on the same scFv showed a similar sensitivity for gB expression. Although lysis of infected target cells was absent, the BiTE antibody construct inhibited HCMV replication by triggering cytokine production. Notably, even strongly diluted supernatants of the activated T cells efficiently blocked the replication of HCMV in infected primary fibroblasts. In summary, our data prove the functionality of the first BiTE antibody construct targeting an HCMV-encoded glycoprotein for inhibiting HCMV replication in infected cells.

Efficacy and safety of bispecific T-cell engager (BiTE) antibody blinatumomab for the treatment of relapsed/refractory acute lymphoblastic leukemia and non-Hodgkin’s lymphoma: a systemic review and meta-analysis

ABSTRACTObjectives: Multiple clinical trials have been conducted to investigate the therapeutic effects of blinatumomab on acute lymphoblastic leukemia (ALL) and non-Hodgkin’s lymphoma (NHL). We did a meta-analysis including 8 clinical trials to verify the efficacy and safety of blinatumomab in patients with relapsed/refractory ALL and NHL.Methods: We searched and investigated all relevant publications from PubMed, Web of Science, Embase, and ClinicalTrials.gov. The primary endpoint was complete remission (CR). The secondary end points were the minimal residual disease (MRD) response, and the adverse effects including cytokine release syndrome (CRS) and grade ≥ 3 neurological events.Results: Our study showed that the pooled CR rate was 0.45 (95% CI: 0.37–0.53) in ALL and 0.20 (0.12–0.27) in NHL respectively. The pooled CR rate is higher in ALL patients with BM blasts <50% than that of patients with BM blasts ≥50% (0.75 versus 0.33). A history of allo-HSCT has no effect on the CR rate. The pooled MRD response rate was 0.42 (95% CI: 0.29–0.54) in ALL. For adverse effects, the pooled occurrence rate of grade ≥3 CRS was 0.04 (95% CI: 0.01–0.06), and the pooled occurrence rate of grade ≥ 3 neurological events was 0.12 (95% CI: 0.08–0.16).Discussion: Blinatumomab is effective in treating relapsed/refractory ALL and NHL. ALL patients manifested better therapeutic response than NHL patients and a reduced tumor load favored the clinical response. For adverse effects, severe CRS and neurological events did not happen very often.Conclusion: Blinatumomab shows valid therapeutic effects and limited adverse response in treating relapsed/refractory ALL and NHL in our meta-analysis

Molecular Imaging of Radiolabeled Bispecific T-Cell Engager 89Zr-AMG211 Targeting CEA-Positive Tumors.

Purpose: AMG 211, a bispecific T-cell engager (BiTE) antibody construct, targets carcinoembryonic antigen (CEA) and the CD3 epsilon subunit of the human T-cell receptor. AMG 211 was labeled with zirconium-89 (89Zr) or fluorescent dye to evaluate the tumor-targeting properties.Experimental Design: 89Zr-AMG211 was administered to mice bearing CEA-positive xenograft tumors of LS174T colorectal adenocarcinoma or BT474 breast cancer cells, as well as CEA-negative HL-60 promyelocytic leukemia xenografts. Biodistribution studies with 2- to 10-μg 89Zr-AMG211 supplemented with unlabeled AMG 211 up to 500-μg protein dose were performed. A BiTE that does not bind CEA, 89Zr-Mec14, served as a negative control. 89Zr-AMG211 integrity was determined in tumor lysates ex vivo Intratumoral distribution was studied with IRDye800CW-AMG211. Moreover, 89Zr-AMG211 was manufactured according to Good Manufacturing Practice (GMP) guidelines for clinical trial NCT02760199Results: 89Zr-AMG211 demonstrated dose-dependent tumor uptake at 6 hours. The highest tumor uptake was observed with a 2-μg dose, and the lowest tumor uptake was observed with a 500-μg dose. After 24 hours, higher uptake of 10-μg 89Zr-AMG211 occurred in CEA-positive xenografts, compared with CEA-negative xenografts. Although the blood half-life of 89Zr-AMG211 was approximately 1 hour, tumor retention persisted for at least 24 hours. 89Zr-Mec14 showed no tumor accumulation beyond background level. Ex vivo autoradiography revealed time-dependent disintegration of 89Zr-AMG211. 800CW-AMG211 was specifically localized in CEA-expressing viable tumor tissue. GMP-manufactured 89Zr-AMG211 fulfilled release specifications.Conclusions: 89Zr-AMG211 showed dose-dependent CEA-specific tumor targeting and localization in viable tumor tissue. Our data enabled its use to clinically evaluate AMG 211 in vivo behavior. Clin Cancer Res; 24(20); 4988-96. ©2018 AACR.

Development of a Tetravalent Anti-GPA33/Anti-CD3 Bispecific Antibody for Colorectal Cancers.

Despite progress in the treatment of colorectal cancer, curing metastatic colorectal cancer remains a major unmet medical need worldwide. Here, we describe a T-cell-engaging bispecific antibody (T-BsAb) to redirect polyclonal cytotoxic T cells to eradicate colorectal cancer. A33, a murine antibody specific for GPA33, was humanized to huA33 and reformatted to huA33-BsAb, based on a novel IgG(L)-scFv platform by linking the anti-CD3 huOKT3 scFv to the carboxyl end of the light chain. This T-BsAb was stably expressed in CHO cells and purified as a stable monomer by HPLC, retaining immunoreactivity by FACS through 30 days of incubation at 37°C. In vitro, it induced activation and expansion of unstimulated T cells and elicited potent T-cell-dependent cell-mediated cytotoxicity against colon and gastric cancer cells in an antigen-specific manner. In vivo, huA33-BsAb inhibited the colon and gastric cancer xenografts, in both subcutaneous and intraperitoneal tumor models. More importantly, both microsatellite instable and microsatellite stable colorectal cancer were effectively eliminated by huA33-BsAb. These preclinical results provide further support for the use of IgG(L)-scFv platform to build BsAb, and especially one targeting GPA33 for colorectal cancer. These preclinical results also support further development of huA33-BsAb as a potential immunotherapeutic. Mol Cancer Ther; 17(10); 2164-75. ©2018 AACR.

Preparation of bispecific antibody-protein adducts by site-specific chemo-enzymatic conjugation

Historically, bispecific antibodies have been constructed through the genetic fusion of additional binding domains to the constant domains of the antibody heavy- or light chains. We present an alternative method for the introduction of additional functional domains to an antibody: site-specific chemo-enzymatic conjugation. This method relies on the combination of site-specific transpeptidases and bioorthogonal chemistry. Transpeptidases are used to site-specifically introduce chemical handles, which can then be used to couple new functional groups by means of a bioorthogonal chemical reaction. We demonstrate site-specific chemo-enzymatic linkage using the transpeptidase sortase (hereafter: sortase) and either a strain-promoted alkyne-azide cycloaddition (SPAAC) or an inverse-electron demand Diels-Alder reaction. Other transpeptidases and bioorthogonal reactions suitable for this purpose exist. Site-specific chemo-enzymatic linkage is a modular method. After introduction of a chemical handle in the antibody, any functional group of interest may then be attached. The modularity of this conjugation method allows for a ‘plug-and-play’ approach to prepare new antibody conjugates, thus bypassing the need for (potentially) laborious genetic fusions. Moreover, as sortase is used to specifically modify the exact C-termini of the antibody chains, the final product will be fused in a C-to-C orientation, which is impossible to achieve by genetic manipulations alone. Here we demonstrate the utility of site-specific chemo-enzymatic conjugation to prepare antibody heterodimers, bispecific T-cell engager antibodies, and immunocytokines, discussing purification methods and describing possible pitfalls.

Abstract 1763: BiTEs vs CAR-Ts: Preclinical targeting of CD133+ brain tumor initiating cells using immunotherapy-based treatment strategies

Abstract Glioblastoma (GBM) is a uniformly fatal primary brain tumor, characterized by extensive cellular heterogeneity. Numerous studies have implicated CD133+ brain tumor initiating cells (BTICs) as drivers of chemo- and radio-resistance in GBM. We have recently demonstrated that a CD133-driven gene signature is predictive of poor overall survival and targeting CD133+ treatment-refractory cells may be an effective strategy to block GBM recurrence. Bispecific T-Cell engaging antibodies (BiTEs) and Chimeric antigen receptors (CARs) present promising immunotherapeutic approaches that have not yet been validated for recurrent GBM. Using CellectSeq, a novel methodology that combines the use of phage-displayed synthetic antibody libraries and DNA sequencing, we developed the CD133-specific monoclonal antibody ‘RW03'. We constructed CD133-specific BiTEs that consist of two arms; one recognizes the tumor antigen (CD133) and the second is specific to the CD3 antigen that binds to human GBMs and PBMC-derived T cells, respectively. We observed BiTEs redirecting T cells to kill GBMs, with greater efficiency observed in CD133high GBMs, validating BiTE target specificity. Incubating T-cells with BiTEs and the CD133high GBMs resulted in increased expression of T cell activation markers. In parallel, we derived the single chain variable fragment (scFv) from RW03 we engineered a second-generation CAR T cell. CD133-specific CAR-T cells were cytotoxic to CD133+ GBMs. Co-culturing CD133 CAR-T cells with GBMs triggered T cell activation and proliferation. Treatment of GBM tumor-bearing mice with CD133-specific CAR-T cells yielded extended survival in mice and significant reductions in brain tumor burden. Furthermore, we uniquely adapted the existing chemoradiotherapy protocol for GBM patients for treatment of immunocompromised mice engrafted with human GBMs. Within this model, we have initiated treatment of recurrent GBM directed against CD133+ BTICs, to allow for a direct prospective comparison of toxicity and efficacy of BiTEs and CAR-T cell strategies. Citation Format: Parvez Vora, Jarrett Adams, Mohini Singh, Chitra Venugopal, Nazanin Tatari, Chirayu Chokshi, Maleeha Qazi, Sabra Salim, Sujeivan Mahendram, David Bakhshinyan, Max London, Neil Savage, Minomi Subapanditha, Nicole McFarlane, James Pan, Jonathan Bramson, Sachdev Sidhu, Jason Moffat, Sheila Singh. BiTEs vs CAR-Ts: Preclinical targeting of CD133+ brain tumor initiating cells using immunotherapy-based treatment strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1763.

Abstract LB-299: Cynomolgus monkey plasma cell gene signature to quantify the in vivo activity of a half-life extended anti-BCMA BiTE® for the treatment of multiple myeloma

Abstract Background: Multiple myeloma (MM) is a hematologic malignancy where abnormal plasma cells (PC) accumulate in the bone marrow (BM). Patients often develop relapsed/refractory disease leading to significant morbidity and mortality. Elimination of residual disease is required for curative treatments. Patient outcome can be improved by using T-cell engaging agents, such as bispecific T-cell engager (BiTE®) antibody constructs, to redirect T cells to tumor cells. B-cell maturation antigen (BCMA), a TNF receptor superfamily member, supports PC survival and is widely expressed on MM and normal PC. Methods: A half-life extended (HLE) anti-BCMA BiTE® (BCMA HLE-BiTE®) antibody construct was generated and characterized in vitro, and in vivo in a mouse xenograft model and in non-human primates (NHP). To quantify on-target activity of the BCMA HLE-BiTE® in NHP it was necessary to follow changes in PC numbers. Because PC are rare (0.1 - 3%) in the BM and blood, detection using traditional assays is not possible. To address this limitation, a PC gene signature was defined and used to develop a quantitative ddPCR assay (sensitivity = 0.01%) to assess the effect of the BCMA HLE-BiTE® in a 12-day repeat-dose NHP study. Results: A BCMA HLE-BiTE® was selected that demonstrated cytotoxic activity using human effector cells (EC50: 0.13 ± 0.07 pM in MM.1R cells) and comparable activity using NHP effector cells. In a sub-cutaneous mouse xenograft model in which BCMA-positive NCI-H929 cells and human PBMC were co-administered, the BCMA HLE-BiTE® completely inhibited tumor formation, in contrast to vehicle controls with/without PBMC. The serum half-life of the BCMA HLE-BiTE® in NHP was 112 hours following a single 15 µg/kg IV dose. The PK/PD relationship in NHP was next evaluated in a 12-day repeat-dose study. A dose-dependent PK behavior as well as depletion of PC in blood and BM was observed, reaching 93% depletion in the blood and 85% in the BM in the high-dose group on day 12. Conclusions: These results demonstrate that the BCMA HLE-BiTE® is potent and effective at inducing cytotoxicity of target cells in vitro and in vivo, and may be suitable for once-weekly dosing in MM patients. This molecule is being evaluated in humans: trial NCT03287908. Citation Format: Ana Goyos, Chi-Ming Li, Petra Deegen, Pamela Bogner, Oliver Thomas, Joachim Wahl, Rebecca Goldstein, Maththias Friedrich, Angela Coxon, Mercedesz Balazs, Tara Arvedson. Cynomolgus monkey plasma cell gene signature to quantify the in vivo activity of a half-life extended anti-BCMA BiTE® for the treatment of multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-299.

Antiviral Activity of HIV gp120-Targeting Bispecific T Cell Engager Antibody Constructs

Today's gold standard in HIV therapy is combined antiretroviral therapy (cART). It requires strict adherence by patients and lifelong medication, which can lower the viral load below detection limits and prevent HIV-associated immunodeficiency but cannot cure patients. The bispecific T cell-engaging (BiTE) antibody technology has demonstrated long-term relapse-free outcomes in patients with relapsed and refractory acute lymphocytic leukemia. Here, we generated BiTE antibody constructs that target the HIV-1 envelope protein gp120 (HIV gp120) using either the scFv B12 or VRC01, the first two extracellular domains (1 + 2) of human CD4 alone or joined to the single chain variable fragment (scFv) of the antibody 17b fused to an anti-human CD3ε scFv. These engineered human BiTE antibody constructs showed engagement of T cells for redirected lysis of HIV gp120-transfected CHO cells. Furthermore, they substantially inhibited HIV-1 replication in peripheral blood mononuclear cells (PBMCs) as well as in macrophages cocultured with autologous CD8+ T cells, the most potent being the human CD4(1 + 2) BiTE [termed CD(1 + 2) h BiTE] antibody construct and the CD4(1 + 2)L17b BiTE antibody construct. The CD4(1 + 2) h BiTE antibody construct promoted HIV infection of human CD4-/CD8+ T cells. In contrast, the neutralizing B12 and the VRC01 BiTE antibody constructs, as well as the CD4(1 + 2)L17b BiTE antibody construct, did not. Thus, BiTE antibody constructs targeting HIV gp120 are very promising for constraining HIV and warrant further development as novel antiviral therapy with curative potential.IMPORTANCE HIV is a chronic infection well controlled with the current cART. However, we lack a cure for HIV, and the HIV pandemic goes on. Here, we showed in vitro and ex vivo that a BiTE antibody construct targeting HIV gp120 resulted in substantially reduced HIV replication. In addition, these BiTE antibody constructs display efficient killing of gp120-expressing cells and inhibited replication in ex vivo HIV-infected PBMCs or macrophages. We believe that BiTE antibody constructs recognizing HIV gp120 could be a very valuable strategy for a cure of HIV in combination with cART and compounds which reverse latency.

Pre-clinical development of TNB-383B, a fully human T-cell engaging bispecific antibody targeting BCMA for the treatment of multiple myeloma.

8034Background: T-cell redirecting therapies such as CAR-T cells and T-cell engaging bispecific antibodies (T-BsAb) targeting B Cell Maturation Antigen (BCMA) have been highly efficacious against r...

A multicenter phase 1 study of solitomab (MT110, AMG 110), a bispecific EpCAM/CD3 T-cell engager (BiTE®) antibody construct, in patients with refractory solid tumors

ABSTRACTWe assessed the tolerability and antitumor activity of solitomab, a bispecific T-cell engager (BiTE®) antibody construct targeting epithelial cell adhesion molecule (EpCAM). Patients with relapsed/refractory solid tumors not amenable to standard therapy received solitomab as continuous IV infusion in a phase 1 dose-escalation study with six different dosing schedules. The primary endpoint was frequency and severity of adverse events (AEs). Secondary endpoints included pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity. Sixty-five patients received solitomab at doses between 1 and 96 µg/day for ≥28 days. Fifteen patients had dose-limiting toxicities (DLTs): eight had transient abnormal liver parameters shortly after infusion start or dose escalation (grade 3, n = 4; grade 4, n = 4), and one had supraventricular tachycardia (grade 3); all events resolved with solitomab discontinuation. Six patients had a DLT of diarrhea: four events resolved (grade 3, n = 3; grade 4, n = 1), one (grade 3) was ongoing at the time of treatment-unrelated death, and one (grade 3) progressed to grade 5 after solitomab discontinuation. The maximum tolerated dose was 24 µg/day. Overall, 95% of patients had grade ≥3 treatment-related AEs, primarily diarrhea, elevated liver parameters, and elevated lipase. Solitomab half-life was 4.5 hours; serum levels plateaued within 24 hours. One unconfirmed partial response was observed. In this study of a BiTE® antibody construct targeting solid tumors, treatment of relapsed/refractory EpCAM-positive solid tumors with solitomab was associated with DLTs, including severe diarrhea and increased liver enzymes, which precluded dose escalation to potentially therapeutic levels.

Immune therapies in acute myeloid leukemia: a focus on monoclonal antibodies and immune checkpoint inhibitors.

This review discusses the rationale, efficacy, and toxicity of a variety of immune approaches being evaluated in the therapy of acute myeloid leukemia (AML) including naked and conjugated monoclonal antibodies, bispecific T-cell engager antibodies, and immune checkpoint blockade via antibodies targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed-death 1 (PD-1). The stellar success of immune therapies that harness the power of T cells in solid tumors and an improved understanding of the immune system in patients with hematologic malignancies have resulted in major efforts to develop immune therapies for the treatment of patients with AML. Monoclonal antibodies in AML therapy include naked antibodies against AML surface antigens such as CD33 (e.g. lintuzumab) or CD38 (e.g. daratumumab), antibodies conjugated to toxins in various anti-CD33 (gemtuzumab ozogamicin, SGN33A, IMGN779) and anti-CD123 (SL-401, SGN-CD123A) formulations, and antibodies conjugated to radioactive particles such as I or Ac-labeled anti-CD33 or anti-CD45 antibodies. Additional antigenic targets of interest in AML include CLL1, CD38, CD25, TIM3, FLT3, and others. Approaches to harness the body's own T cells against AML include antibodies that recruit and induce cytotoxicity of tumor cells by T cells (bispecific T-cell engager [BiTE] such as CD33 x CD3 (e.g. AMG 330) or CD123 x CD3 (e.g. flotetuzumab, JNJ-63709178) or antibodies that block immune checkpoint receptors CTLA4 (e.g. ipilimumab) or PD1/PD-L1 (e.g. nivolumab, pembrolizumab, avelumab) on T cells, unleashing the patients' T cells against leukemic cells. The ongoing trials and well designed correlative interrogation of the immune system in patients treated on such trials will further enhance our understanding and clinical application of immune therapies as single-agent and combination approaches for the treatment of AML.

Development of a fully human t-cell engaging bispecific antibody for the treatment of multiple myeloma.

60 Background: T-cell engaging bispecific antibody (T-BsAb) therapies are highly efficacious and well suited for targets with low expression on tumor cells. Recently, T-BsAbs with high activation of CD3 have been shown to overstimulate T cells, leading to toxicity and decreased efficacy. Teneobio has developed a fully human BCMA-specific T-BsAb using a low-activating αCD3 that is highly effective in vitro and in vivo against MM but stimulates minimal cytokine release. Methods: UniRats were immunized with either CD3 or BCMA antigens and antigen-specific UniAbs were identified by Ab repertoire sequencing and high-throughput gene assembly, expression, and screening. Antigen-specific VH sequences with the desired target affinity were selected using recombinant proteins and cells. In vitro efficacy studies included T-cell activation by cytokine- and tumor cell kill by calcein-release assays. In vivo efficacy of the molecules was evaluated in NSG mice harboring myeloma cells and human PBMCs. Results: BCMA-specific UniAbs bound plasma cells with sub-nM affinity. Strong and weak T cell agonists were identified that bound human T cells with high and low affinities respectively. T-BsAbs with a strong and a weak αCD3 demonstrated T-cell activation and tumor-cell cytotoxicity in vitro; T-BsAbs with a weak αCD3 showed markedly reduced cytokine production even at doses that showed maximum tumor cell lysis. In vivo, BCMAxCD3 T-BsAbs reduced tumor load and increased survival when co-administered with human PBMCs as compared to controls. Conclusions: Our results suggest that T-BsAbs with low-activating αCD3 arms may have a favorable toxicity profile while maintaining efficacy in the treatment of MM.

Bispecific antibodies for cancer therapy: A review.

The ability to produce monoclonal antibodies with defined and distinct specificities has resulted in a vast spectrum of therapeutic monoclonal antibodies including bispecific antibodies (BsAbs). Several types of BsAbs have been produced but the most well-known of these are trispecific antibodies (TrAbs or TrioMabs) and bispecific T cell engager antibodies (BiTE). TrAbs have two variable segments for antigen binding and an Fc component to recruit immune cells. Catumaxomab is a TrAb that has orphan drug status from the Food and Drug Administration (FDA) for EpCam positive gastric and ovarian tumors and was previously approved by the European Medicinal Agency (EMA) for the same indication. One arm of catumaxomab binds to EpCAM, the other binds to CD3 on T cells and the Fc portion recruits immune cells. Catumaxomab is no longer being produced by the manufacturer due to logistic considerations and hence not available in the European market. Blinatumomab is a BiTE that comprises of two variable segments only with one arm binding to CD19 and the other binding to CD3. Blinatumomab has been approved for relapsed or refractory B-cell precursor ALL in adults and children by the FDA. There are over 50 bispecific antibodies currently on clinical trials for various malignancies and the hope is that in the future many of these, with better understanding of principles and techniques of production, will provide treatment options for many different types of cancer.

Advances in targeted therapy for acute myeloid leukaemia.

In the past few years, research in the underlying pathogenic mechanisms of acute myeloid leukaemia (AML) has led to remarkable advances in our understanding of the disease. Cytogenetic and molecular aberrations are the most important factors in determining response to chemotherapy as well as long-term outcome, but beyond prognostication are potential therapeutic targets. Our increased understanding of the pathogenesis of AML, facilitated by next-generation sequencing, has spurred the development of new compounds in the treatment of AML, particularly the creation of small molecules that target the disease on a molecular level. Various new agents, such as tyrosine kinase inhibitors, immune checkpoint inhibitors, monoclonal or bispecific T-cell engager antibodies, metabolic and pro-apoptotic agents are currently investigated within clinical trials. The highest response rates are often achieved when new molecularly targeted therapies are combined with standard chemotherapy. Presented here is an overview of novel therapies currently being evaluated in AML.

ALL in Older Adults

ALL in Older Adults