Avidity driven dual-targeting to achieve tumor selectivity will be explored. Functional screening of antibody panels for lead identification and trispecific T cell engagers for solid and liquid tumors will be discussed.

Immunotherapies directed at MHC-I complexes have expanded the scope of antigens and enabled direct targeting of intracellular oncoproteins at the cell surface. We have shown that covalent drugs such as sotorasib that alkylate mutated residues on KRas G12C can act as haptens to generate unique MHC-I-restricted neoantigens. Using hapten-specific antibodies our results present a strategy to enhance the efficacy of these covalent drugs and overcome their rapidly arising tumor resistance.

F-star generates tetravalent bispecific antibodies by introducing an antigen-binding site into the Fc region of human IgG1 (Fc region with antigen binding, or Fcab region). This antibody format has four antigen-binding sites and provides a focused immune activation upon concurrent binding to both receptors, which has been well tolerated in clinical trials to date. Our proprietary clinical pipeline of bispecific antibodies aims to overcome resistance to current checkpoint inhibitor therapies and improve on the benefit of checkpoint inhibitors.

Designing efficacious therapeutics with conditional activity towards specific cells or tissues is the next frontier in precision medicine. To achieve this goal, we developed a platform for the design and identification of ultra-rare, fully human, multi-specific biologics, called Tentacles, with exquisite cell/tissue-specific activity from libraries of >1 million molecules. Data for our first Tentacle drug candidate combining LAG3 inhibition with LAG3-dependent IL2R activation will be described.

Harnessing the immune system has revolutionized cancer treatment. However, on-target off-tumor toxicities limit therapeutic potential. At the heart of REV403 TwoGATE is the split anti-CD3 paratope enabling a true dual Ag “AND” gate by targeting the inactive components to EGFR and PDL1, respectively on the same tumor cell before CD3 binding complex reassembly. REV403 has pM potency in vitro, potently regresses tumors in vivo, and is well-tolerated in non-human primates.

Ichnos’ BEAT platform (Bispecific Engagement by Antibodies based on the TCR) facilitates design of multi-specific antibodies using efficient heavy-chain heterodimerization and a common light chain. Employing this platform, we have generated a series of multi-specific (tri- and tetra-specific, and 2+1 biparatopic bispecific) antibodies, which engage most major types of immune effector cells from the peripheral blood mononuclear fraction. In this presentation we will illustrate the advantages of BEAT-based multi-specific antibodies, which permit efficiently leveraging avidity, increased specificity, and potency of experimental therapeutics built by employing Ichnos’ antibody platform. 

• What approaches can be taken to align novel mechanisms of action of bispecific with the biology of disease? 
• How can preclinical model systems be used to effectively generate translational hypotheses?
• What considerations are important when designing biomarker strategies for bispecifics?

Using a combination of I-TASSER and Rosetta protein modeling software, we predicted the structure of >4000 CDP mini-proteins. From a diversity library generated around those that showed in silico binding to PD-L1, we used mammalian display-based screening and affinity maturation to identify a high-affinity (KD=202 pM) binder. When incorporated into a bispecific format, this CDP-based PD-L1 binder outperformed an antibody-based comparator in multiple solid tumor models and showed some activity in diffuse midline glioma (DMG) models despite a relatively intact blood-brain barrier.

E3 ubiquitin ligases with exposed extracellular domains represent attractive tools for targeted protein degradation approaches. Indeed, through developing Proteolysis Targeting Antibodies (PROTABs) we enable the repurposing of ZNFR3, a Wnt-responsive E3 ubiquitin ligase, as a tumor-specific cell-surface protein degrader. Importantly, PROTABs are also amendable to additional cell-surface targets and ligases. Altogether, this strategy expands on current degrader technologies allowing the development of effective, bioavailable, and tissue-selective cell-surface protein degraders.

Triggering receptor expressed on myeloid cells 2 (TREM2) plays a crucial role in regulating microglial functions and removal of amyloid plaques in Alzheimer’s disease (AD). We recently reported a novel TREM2 targeting bispecific antibody (TVD-Ig/αTfR) with tetra-variable domains targeting TREM2 (TVD-Ig), and a single chain variable fragment (scFv) binding to transferrin receptor (TfR). The TVD-Ig/αTfR bispecific antibody improved antibody brain entry by more than 10-fold in comparison with the anti-TREM2 counterpart.

Treatment-emergent (TE) ADAs and pre-existing (PE) ADAs became a major hurdle in the successful development of multi-specific antibodies. A limited set of point mutations can prevent binding of PE ADAs to the framework and generation of TE ADAs to CDR regions. In silico design, immunogenicity prediction and an exhaustive array of characterization assays led to the design of optimized sequences that facilitate better development of bi- and multi-specific antibodies.

ZW171 is a mesothelin (MSLN)-targeting T cell engager with bivalent binding to MSLN and a novel CD3 binding domain. By tuning affinity and format, we achieved a molecule with potent MSLN-specific activity both in vitro and in vivo, with minimal MSLN-independent T cell binding and activation. Development data suggest that ZW171 has the potential to be an efficacious and safe therapeutic for the treatment of MSLN-expressing cancers.

Clinical development of IL-12 therapy is constrained by systemic toxicity that limits therapeutic dose and efficacy. BCA356 is a novel bifunctional molecule designed by in silico screening to identify IL-12 variants. Lead IL-12v is fused with a high-affinity anti-CAIX antibody in a stable structural format for effectively targeting tumor site only. Preclinical studies suggest that BCA356 is efficacious with optimal immune modulation and safe for the treatment of CAIX expressing tumors.