T cell engaging bispecific antibodies targeting CD33 IgV and IgC domains for the treatment of acute myeloid leukemia.

Acute myeloid leukemia (AML) remains one of the most challenging hematological malignancies. Despite progress in therapeutics, majority of patients succumb to this neoplasm. CD33 is a proven therapeutic target, given its expression on most AML cells. Almost all anti-CD33 antibodies target the membrane distal immunoglobulin V (IgV) domain of the CD33 extracellular domain. In this manuscript, we present data on three bispecific antibodies (BsAbs) against the CD33 IgV and membrane proximal immunoglobulin C (IgC) domains. We use in vitro binding and cytotoxicity assays to show the effect of these BsAbs on AML cell lines. We also use immunodeficient mice-bearing leukemias from cell lines and patient-derived xenografts to show the effect of these BsAbs in vivo. In vitro, the IgV-targeting BsAb had higher binding to AML cell lines using flow cytometry and delivered more potent cytotoxicity in T-cell-dependent cytotoxicity assays; importantly, the IgC domain-targeting outperformed the IgV domain-targeting BsAb in medullary and extramedullary leukemia animal models. These data support further clinical development of this BsAb for first-in-human phase I clinical trial.

Hoseini SS ，Vadlamudi M ，Espinosa-Cotton M ，Tran H ，Feng Y ，Guo HF ，Xu H ，Cheung I ，Cheung NV ... -  《Journal for ImmunoTherapy of Cancer》

A dual-targeting approach with anti-IL10R CAR-T cells engineered to release anti-CD33 bispecific antibody in enhancing killing effect on acute myeloid leukemia cells.

Immunotherapies, including chimeric antigen receptor (CAR) T cells and bispecific antibodies (BsAbs), encounter several challenges in the management of acute myeloid leukemia (AML), including limited persistence of these treatments, antigen loss and resistance of leukemia stem cells (LSCs) to therapy. Here, we proposed a novel dual-targeting approach utilizing engineered anti-IL10R CAR-T cells to secrete bispecific antibodies targeting CD33. This innovative strategy, rooted in our previous research which established a connection between IL-10 and the stemness of AML cells, designed to improve targeting efficiency and eradicate both LSCs and AML blasts. We first demonstrated the superior efficacy of this synergistic approach in eliminating AML cell lines and primary cells expressing different levels of the target antigens, even in cases of low CD33 or IL10R expression. Furthermore, the IL10R CAR-T cells that secret anti-CD33 bsAbs (CAR.BsAb-T), exhibited an enhanced activation and induction of cytotoxicity not only in IL10R CAR-T cells but also in bystander T cells, thereby more effectively targeting CD33-positive tumor cells. Our in vivo experiments provided additional evidence that CAR.BsAb-T cells could efficiently redirect T cells, reduce tumor burden, and demonstrate no significant toxicity. Additionally, delivering bsAbs locally to the tumor sites through this strategy helps mitigate the pharmacokinetic challenges typically associated with the rapid clearance of prototypical bsAbs. Overall, the engineering of a single-vector targeting IL10R CAR, which subsequently secretes CD33-targeted bsAb, addresses the issue of immune escape due to the heterogeneous expression of IL10R and CD33, and represents a promising progress in AML therapy aimed at improving treatment outcomes.

Yan Z ，Gu R ，Ma H ，Chen N ，Zhang T ，Xu Y ，Qiu S ，Xing H ，Tang K ，Tian Z ，Rao Q ，Wang M ，Wang J ... -  《-》

A potent tetravalent T-cell-engaging bispecific antibody against CD33 in acute myeloid leukemia.

Acute myeloid leukemia (AML), the most common acute leukemia in adults and the second most common cancer in children, is still a lethal disease in the majority of patients, but immunologic approaches have improved outcome. Bispecific antibodies (BsAbs) are novel immunotherapeutics that can redirect immune cells against AML. We now report a tetravalent (2+2) humanized BsAb in the immunoglobulin G light chain single chain fragment variable [IgG(L)-scFv] format to engage polyclonal T cells to kill CD33+ AML targets. In vitro, this BsAb demonstrated strong antigen-specific T-cell-dependent cell-mediated cytotoxicity (TDCC) with an 50% effective concentration (EC50) in the femtomolar range that translated into treatment of established human AML IV xenografts in vivo. Importantly, it could redirect intraperitoneally injected T cells to ablate established and rapidly growing extramedullary subcutaneous AML xenografts in vivo. Furthermore, internalization of CD33 upon BsAb binding was identical to that of a bivalent (1+1) heterodimer, both being substantially less than anti-CD33 IgG. In contrast to the heterodimer, the tetravalent IgG-scFv BsAb was >10-fold more efficient in TDCC of AML cells in vitro and in vivo. This BsAb did not react with and did not kill CD38-CD34+ hematopoietic stem cells from cord blood. We conclude that the novel anti-CD33 IgG(L)-scFv BsAb construct reported here is a potential candidate for clinical development.

Hoseini SS ，Guo H ，Wu Z ，Hatano MN ，Cheung NV ... -  《-》

Bispecific antibody releasing-mesenchymal stromal cell machinery for retargeting T cells towards acute myeloid leukemia blasts.

Aliperta R ，Cartellieri M ，Feldmann A ，Arndt C ，Koristka S ，Michalk I ，von Bonin M ，Ehninger A ，Bachmann J ，Ehninger G ，Bornhäuser M ，Bachmann MP ... -  《Blood Cancer Journal》

Therapeutic afucosylated monoclonal antibody and bispecific T-cell engagers for T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease with a poor cure rate for relapsed/resistant patients. Due to the lack of T-cell restricted targetable antigens, effective immune-therapeutics are not presently available and the treatment of chemo-refractory T-ALL is still an unmet clinical need. To develop novel immune-therapy for T-ALL, we generated an afucosylated monoclonal antibody (mAb) (ahuUMG1) and two different bispecific T-cell engagers (BTCEs) against UMG1, a unique CD43-epitope highly and selectively expressed by T-ALL cells from pediatric and adult patients. UMG1 expression was assessed by immunohistochemistry (IHC) on a wide panel of normal tissue microarrays (TMAs), and by flow cytometry on healthy peripheral blood/bone marrow-derived cells, on 10 different T-ALL cell lines, and on 110 T-ALL primary patient-derived cells. CD43-UMG1 binding site was defined through a peptide microarray scanning. ahuUMG1 was generated by Genetic Glyco-Engineering technology from a novel humanized mAb directed against UMG1 (huUMG1). BTCEs were generated as IgG1-(scFv)2 constructs with bivalent (2+2) or monovalent (2+1) CD3ε arms. Antibody dependent cellular cytotoxicity (ADCC), antibody dependent cellular phagocytosis (ADCP) and redirected T-cell cytotoxicity assays were analysed by flow cytometry. In vivo antitumor activity of ahUMG1 and UMG1-BTCEs was investigated in NSG mice against subcutaneous and orthotopic xenografts of human T-ALL. Among 110 T-ALL patient-derived samples, 53 (48.1%) stained positive (24% of TI/TII, 82% of TIII and 42.8% of TIV). Importantly, no expression of UMG1-epitope was found in normal tissues/cells, excluding cortical thymocytes and a minority (<5%) of peripheral blood T lymphocytes. ahUMG1 induced strong ADCC and ADCP on T-ALL cells in vitro, which translated in antitumor activity in vivo and significantly extended survival of treated mice. Both UMG1-BTCEs demonstrated highly effective killing activity against T-ALL cells in vitro. We demonstrated that this effect was specifically exerted by engaged activated T cells. Moreover, UMG1-BTCEs effectively antagonized tumor growth at concentrations >2 log lower as compared with ahuUMG1, with significant mice survival advantage in different T-ALL models in vivo. Altogether our findings, including the safe UMG1-epitope expression profile, provide a framework for the clinical development of these innovative immune-therapeutics for this still orphan disease.

Caracciolo D ，Riillo C ，Ballerini A ，Gaipa G ，Lhermitte L ，Rossi M ，Botta C ，Duroyon E ，Grillone K ，Gallo Cantafio ME ，Buracchi C ，Alampi G ，Gulino A ，Belmonte B ，Conforti F ，Golino G ，Juli G ，Altomare E ，Polerà N ，Scionti F ，Arbitrio M ，Iannone M ，Martino M ，Correale P ，Talarico G ，Ghelli Luserna di Rorà A ，Ferrari A ，Concolino D ，Sestito S ，Pensabene L ，Giordano A ，Hildinger M ，Di Martino MT ，Martinelli G ，Tripodo C ，Asnafi V ，Biondi A ，Tagliaferri P ，Tassone P ... -  《Journal for ImmunoTherapy of Cancer》