A novel C2 domain binding CD33xCD3 bispecific antibody with potent T-cell redirection activity against acute myeloid leukemia

Abstract

CD33 is expressed in 90% of patients with acute myeloid leukemia (AML), and its extracellular portion consists of a V domain and a C2 domain. A recent study showed that a single nucleotide polymorphism (SNP), rs12459419 (C > T), results in the reduced expression of V domain–containing CD33 and limited efficacy of V domain–binding anti-CD33 antibodies. We developed JNJ-67571244, a novel human bispecific antibody capable of binding to the C2 domain of CD33 and to CD3, to induce T-cell recruitment and CD33+ tumor cell cytotoxicity independently of their SNP genotype status. JNJ-67571244 specifically binds to CD33-expressing target cells and induces cytotoxicity of CD33+ AML cell lines in vitro along with T-cell activation and cytokine release. JNJ-67571244 also exhibited statistically significant antitumor activity in vivo in established disseminated and subcutaneous mouse models of human AML. Furthermore, this antibody depletes CD33+ blasts in AML patient blood samples with concurrent T-cell activation. JNJ-67571244 also cross-reacts with cynomolgus monkey CD33 and CD3, and dosing of JNJ-67571244 in cynomolgus monkeys resulted in T-cell activation, transient cytokine release, and sustained reduction in CD33+ leukocyte populations. JNJ-67571244 was well tolerated in cynomolgus monkeys up to 30 mg/kg. Lastly, JNJ-67571244 mediated efficient cytotoxicity of cell lines and primary samples regardless of their SNP genotype status, suggesting a potential therapeutic benefit over other V-binding antibodies. JNJ-67571244 is currently in phase 1 clinical trials in patients with relapsed/refractory AML and high-risk myelodysplastic syndrome.

One size does not fit all: navigating the multi-dimensional space to optimize T-cell engaging protein therapeutics

“…remained unclear whether there is a gradual or abrupt decrease in potency when the antigen epitope distance to the target cell membrane is increased. Three more recent publications, using other TAAs, including FcRH5, 13 ROR1, 32 and CD33, 33 further substantiated the findings that targeting membrane-proximal epitopes tends to yield molecules with greater potency. Here, using small EGF-like domain of ~3 nm as the structural spacer unit and two bispecific molecules with different arm lengths of the paratopes, we offer a more detailed picture of how increasing antigen epitope distance to target cell membrane affects cytotoxicity for both DbFc and IgG-based formats (Figure 2).…”

Emerging agents and regimens for AML

“…JNJ-67571244 demonstrated good in vitro cytotoxicity of CD33 + AML cell lines and also exhibited significant antitumor activity in vivo in mouse models of human AML. JNJ-67571244 is currently in a phase 1 clinical trial in patients with relapsed/refractory AML and high-risk myelodysplastic syndrome (#NCT03915379) [ 109 ].…”

Engineered Multifunctional Nano‐ and Biological Materials for Cancer Immunotherapy

“…One study made use of this through the synthesis of an anti‐CD3 x anti‐CD33 duobody (JN67571244) antibody format. [ 133 ] With CD33 being restricted to hematopoietic cell lineages and expressed in blasts and leukemic cells in 85–90% of patients, this targeted BsAb was used to target the C2‐domain of CD33 to induce T cell‐mediated killing. At a range of concentrations, JN67571244 was able to elicit T‐cell mediated toxicity in vitro against primary acute myeloid leukemia (AML) cells and induce potent CD25 expression/activation, more so than the nullxCD3 control system.…”