12 research outputs found
Toward clinical development of SYD985, a novel HER2-targeting antibody-drug conjugate (ADC).
Improved in vivo anti-tumor effects of IgA-Her2 antibodies through half-life extension and serum exposure enhancement by FcRn targeting
Antibody therapy is a validated treatment approach for several malignancies. All currently clinically applied therapeutic antibodies (Abs) are of the IgG isotype. However, not all patients respond to this therapy and relapses can occur. IgA represents an alternative isotype for antibody therapy that engages FcαRI expressing myeloid effector cells, such as neutrophils and monocytes. IgA Abs have been shown to effectively kill tumor cells both in vitro and in vivo. However, due to the short half-life of IgA Abs in mice, daily injections are required to reach an effect comparable to IgG Abs. The relatively long half-life of IgG Abs and serum albumin arises from their capability of interacting with the neonatal Fc receptor (FcRn). As IgA Abs lack a binding site for FcRn, we generated IgA Abs with the variable regions of the Her2-specific Ab trastuzumab and attached an albumin-binding domain (ABD) to the heavy or light chain (HCABD/LCABD) to extend their serum half-life. These modified Abs were able to bind albumin from different species in vitro. Furthermore, tumor cell lysis of IgA-Her2-LCABD Abs in vitro was similar to unmodified IgA-Her2 Abs. Pharmacokinetic studies in mice revealed that the serum exposure and half-life of the modified IgA-Her2 Abs was extended. In a xenograft mouse model, the modified IgA1 Abs exhibited a slightly, but significantly, improved anti-tumor response compared to the unmodified Ab. In conclusion, empowering IgA Abs with albumin-binding capacity results in in vitro and in vivo functional Abs with an enhanced exposure and prolonged half-life
A Platform for the Generation of Site-Specific AntibodyDrug Conjugates That Allows for Selective Reduction of Engineered Cysteines
Preclinical Profile of the HER2-Targeting ADC SYD983/SYD985: Introduction of a New Duocarmycin-Based Linker-Drug Platform
Simultaneous Targeting of FcγRs and FcαRI Enhances Tumor Cell Killing
Efficacy of anticancer monoclonal antibodies (mAb) is limited by the exhaustion of effector mechanisms. IgG mAbs mediate cellular effector functions through FcγRs expressed on effector cells. IgA mAbs can also induce efficient tumor killing both in vitro and in vivo. IgA mAbs recruit FcαRI-expressing effector cells and therefore initiate different effector mechanisms in vivo compared with IgG. Here, we studied killing of tumor cells coexpressing EGFR and HER2 by the IgG mAbs cetuximab and trastuzumab and their IgA variants. In the presence of a heterogeneous population of effector cells (leukocytes), the combination of IgG and IgA mAbs to two different tumor targets (EGFR and HER2) led to enhanced cytotoxicity compared with each isotype alone. Combination of two IgGs or two IgAs or IgG and IgA against the same target did not enhance cytotoxicity. Increased cytotoxicity relied on the presence of both the peripheral blood mononuclear cell and the polymorphonuclear (PMN) fraction. Purified natural killer cells were only cytotoxic with IgG, whereas cytotoxicity induced by PMNs was strong with IgA and poor with IgG. Monocytes, which coexpress FcγRs and FcαRI, also displayed increased cytotoxicity by the combination of IgG and IgA in an overnight killing assay. Coinjection of cetuximab and IgA2-HER2 resulted in increased antitumor effects compared with either mAb alone in a xenograft model with A431-luc2-HER2 cells. Thus, the combination of IgG and IgA isotypes optimally mobilizes cellular effectors for cytotoxicity, representing a promising novel strategy to improve mAb therapy
A comparison of anti-HER2 IgA and IgG1 in vivo efficacy is facilitated by high N-glycan sialylation of the IgA
Proteomic
Improved in vivo anti-tumor effects of IgA-Her2 antibodies through half-life extension and serum exposure enhancement by FcRn targeting
Design, Synthesis, and Evaluation of Linker-Duocarmycin Payloads: Toward Selection of HER2-Targeting Antibody–Drug Conjugate SYD985
Antibody–drug conjugates (ADCs)
that are currently on the
market or in clinical trials are predominantly based on two drug classes:
auristatins and maytansinoids. Both are tubulin binders and block
the cell in its progression through mitosis. We set out to develop
a new class of linker-drugs based on duocarmycins, potent DNA-alkylating
agents that are composed of a DNA-alkylating and a DNA-binding moiety
and that bind into the minor groove of DNA. Linker-drugs were evaluated
as ADCs by conjugation to the anti-HER2 antibody trastuzumab via reduced
interchain disulfides. Duocarmycin <b>3b</b>, bearing an imidazo[1,2-<i>a</i>]pyridine-based DNA-binding unit, was selected as the drug
moiety, notably because of its rapid degradation in plasma. The drug
was incorporated into the linker-drugs in its inactive prodrug form, <i>seco</i>-duocarmycin <b>3a</b>. Linker attachment to the
hydroxyl group in the DNA-alkylating moiety was favored over linking
to the DNA-binding moiety, as the first approach gave more consistent
results for in vitro cytotoxicity and generated ADCs with excellent
human plasma stability. Linker-drug <b>2</b> was eventually
selected based on the properties of the corresponding trastuzumab
conjugate, SYD983, which had an average drug-to-antibody ratio (DAR)
of about 2. SYD983 showed subnanomolar potencies against multiple
human cancer cell lines, was highly efficacious in a BT-474 xenograft
model, and had a long half-life in cynomolgus monkeys, in line with
high stability in monkey and human plasma. Studies comparing ADCs
with a different average DAR showed that a higher average DAR leads
to increased efficacy but also to somewhat less favorable physicochemical
and toxicological properties. Fractionation of SYD983 with hydrophobic
interaction chromatography resulted in SYD985, consisting of about
95% DAR2 and DAR4 species in an approximate 2:1 ratio and having an
average DAR of about 2.8. SYD985 combines several favorable properties
from the unfractionated ADCs with an improved homogeneity. It was
selected for further development and recently entered clinical Phase
I evaluation