An Optimized Full-Length FLT3/CD3 Bispecific Antibody Demonstrates Potent Anti-leukemia Activity and Reversible Hematological Toxicity

Yeung, Yik Andy; Krishnamoorthy, Veena; Dettling, Danielle; Sommer, Cesar; Poulsen, Kris; Ni, Irene; Pham, Amber; Chen, Wei; Liao-Chan, Sindy; Lindquist, Kevin C.; Chin, Sherman M.; Chunyk, Allison G.; Hu, Wenyue; Sasu, Barbra J.; Chaparro‐Riggers, Javier; Djuretic, Ivana

doi:10.1016/j.ymthe.2019.12.014

Cited by 29 publications

(24 citation statements)

References 48 publications

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“…Ongoing trials are investigating targeting FLT3 through an IgG1 antibody (FLYSYN; NCT02789254), with promising preliminary efficacy data ( 123 ), as well as via an anti-FLT3 antibody drug conjugate ( 124 ) (NCT02864290). In addition, an anti-FLT3/anti-CD3 bi-specific antibody has shown promise in preclinical models as well ( 125 ). Finally, FLT3 may represent a potential target for chimeric antigen receptor T cell (CART) therapy ( 126 ), including in combination with established FLT3 inhibitors ( 127 ).…”

Section: Novel Flt3 Inhibitors In Developmentmentioning

confidence: 99%

FLT3 Mutations in Acute Myeloid Leukemia: Key Concepts and Emerging Controversies

2020

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The FLT3 receptor is overexpressed on the majority of acute myeloid leukemia (AML) blasts. Mutations in FLT3 are the most common genetic alteration in AML, identified in approximately one third of newly diagnosed patients. FLT3 internal tandem duplication mutations (FLT3-ITD) are associated with increased relapse and inferior overall survival. Multiple small molecule inhibitors of FLT3 signaling have been identified, two of which (midostaurin and gilteritinib) are currently approved in the United States, and many more of which are in clinical trials. Despite significant advances, resistance to FLT3 inhibitors through secondary FLT3 mutations, upregulation of parallel pathways, and extracellular signaling remains an ongoing challenge. Novel therapeutic strategies to overcome resistance, including combining FLT3 inhibitors with other antileukemic agents, development of new FLT3 inhibitors, and FLT3-directed immunotherapy are in active clinical development. Multiple questions regarding FLT3-mutated AML remain. In this review, we highlight several of the current most intriguing controversies in the field including the role of FLT3 inhibitors in maintenance therapy, the role of hematopoietic cell transplantation in FLT3-mutated AML, use of FLT3 inhibitors in FLT3 wild-type disease, significance of non-canonical FLT3 mutations, and finally, emerging concerns regarding clonal evolution.

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Section: Novel Flt3 Inhibitors In Developmentmentioning

confidence: 99%

FLT3 Mutations in Acute Myeloid Leukemia: Key Concepts and Emerging Controversies

2020

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“…While standard therapy (induction chemo-and consolidation therapy) does offer a curative first-line therapy to those eligible [1], leukemic stem cells (LSCs) drive disease relapse in the majority of responders [2]. In spite of significant advances, including allogeneic stem cell transplantation and a growing molecular tailoring of treatment toward driver pathways such as FLT3 [3], the prognosis of relapsed or refractory AML remains poor.…”

Section: Introductionmentioning

confidence: 99%

A modular and controllable T cell therapy platform for acute myeloid leukemia

et al. 2021

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Targeted T cell therapy is highly effective in disease settings where tumor antigens are uniformly expressed on malignant cells and where off-tumor on-target-associated toxicity is manageable. Although acute myeloid leukemia (AML) has in principle been shown to be a T cell-sensitive disease by the graft-versus-leukemia activity of allogeneic stem cell transplantation, T cell therapy has so far failed in this setting. This is largely due to the lack of target structures both sufficiently selective and uniformly expressed on AML, causing unacceptable myeloid cell toxicity. To address this, we developed a modular and controllable MHC-unrestricted adoptive T cell therapy platform tailored to AML. This platform combines synthetic agonistic receptor (SAR) -transduced T cells with AML-targeting tandem single chain variable fragment (scFv) constructs. Construct exchange allows SAR T cells to be redirected toward alternative targets, a process enabled by the short half-life and controllability of these antibody fragments. Combining SAR-transduced T cells with the scFv constructs resulted in selective killing of CD33+ and CD123+ AML cell lines, as well as of patient-derived AML blasts. Durable responses and persistence of SAR-transduced T cells could also be demonstrated in AML xenograft models. Together these results warrant further translation of this novel platform for AML treatment.

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“…An anti-CD3 antibody, H2B4, has previously been used in an asymmetrical heterodimeric IgG format as part of an anti-FLT3 T-BsAB and has demonstrated potent in vivo efficacy in liquid tumor settings. 33 However, H2B4 in the diabody-Fc format with binding domains directed against several other targets showed poor stability, nonspecific binding (polyreactivity) and clipping in CDR H2 during stable cell expression but not transient expression (data not shown), and therefore required optimization for use in this format. To address these issues, the CDRs of the H2B4 variable light (VL) domain were grafted from the original light chain, VK4-01, to VK1-39 germline frameworks.…”

Section: Resultsmentioning

confidence: 99%

“…A humanized anti-CD3 antibody, H2B4, with specificity to human and cynomolgus monkey CD3ε was generated by mouse immunization followed by humanization into preferred human frameworks as described previously. 33 CDR regions of H2B4 VL were grafted into the VK1-39 framework using conventional grafting methods 37 and gene synthesis (Blue Heron Bio, Bothell, WA). Following re-grafting of the VL CDRs, mutations were introduced in the CDR regions to improve stability, to reduce proteolytic degradation at or near previously determined cleavage sites, and to reduce potential charge patches within the CDRs.…”

Section: Methodsmentioning

confidence: 99%

Discovery and optimization of a novel anti-GUCY2c x CD3 bispecific antibody for the treatment of solid tumors

Root

Guntas

Katragadda

et al. 2021

mAbs

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We report here the discovery and optimization of a novel T cell retargeting anti-GUCY2C x anti-CD3ε bispecific antibody for the treatment of solid tumors. Using a combination of hybridoma, phage display and rational design protein engineering, we have developed a fully humanized and manufacturable CD3 bispecific antibody that demonstrates favorable pharmacokinetic properties and potent in vivo efficacy. Anti-GUCY2C and anti-CD3ε antibodies derived from mouse hybridomas were first humanized into well-behaved human variable region frameworks with full retention of binding and T-cell mediated cytotoxic activity. To address potential manufacturability concerns, multiple approaches were taken in parallel to optimize and de-risk the two antibody variable regions. These approaches included structure-guided rational mutagenesis and phage display-based optimization, focusing on improving stability, reducing polyreactivity and self-association potential, removing chemical liabilities and proteolytic cleavage sites, and de-risking immunogenicity. Employing rapid library construction methods as well as automated phage display and high-throughput protein production workflows enabled efficient generation of an optimized bispecific antibody with desirable manufacturability properties, high stability, and low nonspecific binding. Proteolytic cleavage and deamidation in complementarity-determining regions were also successfully addressed. Collectively, these improvements translated to a molecule with potent single-agent in vivo efficacy in a tumor cell line adoptive transfer model and a cynomolgus monkey pharmacokinetic profile (half-life>4.5 days) suitable for clinical development. Clinical evaluation of PF-07062119 is ongoing.

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An Optimized Full-Length FLT3/CD3 Bispecific Antibody Demonstrates Potent Anti-leukemia Activity and Reversible Hematological Toxicity

Cited by 29 publications

References 48 publications

FLT3 Mutations in Acute Myeloid Leukemia: Key Concepts and Emerging Controversies

FLT3 Mutations in Acute Myeloid Leukemia: Key Concepts and Emerging Controversies

A modular and controllable T cell therapy platform for acute myeloid leukemia

Discovery and optimization of a novel anti-GUCY2c x CD3 bispecific antibody for the treatment of solid tumors

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