T cell engaging biologics is a class of novel and promising immune-oncology compounds acting by leveraging the immune system to eradicate cancer. Cytokine release syndrome (CRS), the most common toxicity observed, is a cascade of immunological events initiated by the synchronous release of cytokines from overactivated T cells. Here we will describe different strategies to limit CRS.

Bispecific antibodies can enable therapeutic modalities inaccessible by traditional mAbs. Generally, the two targets can be engaged in trans (bridging two cells) or in cis (on the same cell). We engineered B7H3 x CD28 and PDL1 x CD28 bispecifics that provide CD28 costimulation only in the presence of their respective targets (trans) and PD1 x TGFbR2 and CD5 x TGFbR2 bispecifics that block TGFbR2 selectively on target-positive T cells (cis).

• Optimal affinity designs for dual TAA targeting bispecifics, balancing between efficacy and safety
• Leveraging the affinity difference of the two arms to enrich bispecific antibodies to the tumors
• Increasing the affinity of the CD3 arm in a bispecific to overcome low TAA density or poor T cell activation
• Reducing the affinity of the CD3 arm in a bispecific to mitigate CRS​

• Challenges: Cytokine release syndrome, activation-induced T cell death, poor efficacy in solid tumors
• Future directions: Low affinity CD3 engagers, activatable CD3 engagers, combinations with CPI​

Antibody-based immunotherapy is a promising strategy in cancer treatment. IgG eliminates tumor cells through NK cell-mediated ADCC and macrophage-mediated antibody-dependent phagocytosis. Neutrophils have been largely overlooked as potential effector cells because IgG ineffectively recruits neutrophils. By contrast, IgA potently activates neutrophils and induces migration through FcaRI. IgA has however poorer half-life and does not activate NK cells. Bispecific antibodies targeting FcaRI combine best of both worlds, and will be discussed.

Numab’s MATCH platform supports the development of multi-specific therapeutics with improved efficacy and safety profiles. An update on NM21-1480, our scMATCH3 PD-L1/4-1BB, currently in Phase I clinical testing, is presented. The presentation focuses on the importance of affinity, valency, and epitope selection to optimally address target biology. Also, the design and preclinical proof-of-concept data on T cell redirecting multi-specifics against MSLN and ROR1, in combination with NM21-1480, will be discussed.

• We present data discussing how increased specific avidity, those TCR’s with strongest antigen binding with the lowest background, correlate with improved TCR function in vitro and in vivo.   
• How CAR T and TCR T avidity is significantly more correlative to in vivo outcome than either cytotoxicity assays or IFN-g release. 
• Methods for using cell avidity to screen constructs and more reliably select lead candidates

Anti-CD47/anti-TAA bispecific antibodies with IgG1-Fc are developed to achieve strengthened potency by recruiting both NK cells and macrophages, broaden tumor-killing spectrum by targeting both CD47 and TAA, and potentially achieve durable efficacy by increasing neoantigen presentation and T-cell activation. These IgG-like antibodies are assembled using Phane’s PACboy and SPECpair technology platforms to retain mAb-like physicochemical and pharmacokinetic properties and are fit for platform in the conventional mAb manufacturing process.

Bispecific molecules targeting CD3 and tumor-associated antigens are attractive therapeutics because they harness the power of T cells to destroy tumor cells. While T cell retargeting bispecifics are promising cancer therapies, their complex format could pose developability challenges including poor thermal stability, non-specific binding, clipping, and chemical liabilities that can be improved through rational design/engineering campaigns. Process challenges are mitigated and impurities are well-characterized to enable manufacturability.

INV322 is a next-generation Treg depleter. Using Invenra’s SNIPER B-Body Technology, this novel human IgG1 bispecific antibody is designed to capitalize on avidity to deplete Tregs specifically in the tumor microenvironment. With respect to MOA, INV322 blocks both targets and elicits ADCC. We will show preclinical data supportive of its therapeutic potential. IND-enabling activities are underway.

Our novel, automated, high-throughput engineering platform enables the fast generation of large panels of multi-specific variants (up to 10,000) giving rise to large data sets (more than 100,000 data points). Herein we demonstrate how our platform is utilized for the optimization of next-generation biologics.

Glioblastoma (GBM) is a heterogeneous, incurable primary brain tumor. IL-13RA2, EphA2, EphA3, and EphB2 plasma membrane receptors are over-expressed in GBM, but not in normal brain. We have pursued the novel idea of targeting all four receptors with one pharmaceutical agent based on an IgG-Fc scaffold with natural ligands. We have successfully produced drug conjugates with various chemotherapeutics/toxins that are highly effective in vitro and in vivo.

We created novel fully human dual-specific antibodies that both block both PD-L1 and PD-L2 with high affinity and target PD-Ligand cells for depletion via ADCC and ADCP. The lead antibody outperforms PD-1 blockade across both "hot" and "cold" cancers through a unique combination of stromal depletion, complete PD-1 circuit blockade and direct anti-tumor cytolysis. These antibodies appear safe in both mice and primates and will enter Phase I in 2022.

Allogeneic hematopoietic stem cell transplantation (alloHSCT) can cure chronic lymphocytic leukemia (CLL). Using a target agnostic phage display approach that was based on a post-alloHSCT antibody library, we discovered CLL patient-derived monoclonal antibodies (mAbs) targeting Siglec-6. The mAbs were engineered into various Siglec-6 × CD3 bispecific antibody formats which successfully lysed CLL cell lines in vitro and in vivo and primary CLL cells ex vivo, while sparing healthy B cells.

T-cell engagers (TCE) have been effective in hematologic cancers but have shown limited efficacy in solid tumors because of on-target, off-tumor toxicities or cytokine release syndrome that limits the therapeutic window for the antibody. We developed a novel TCE using our unique discovery platform which shows selective bivalent antigen binding to target tumor cells overexpressing target antigen while avoiding normal tissues expressing low levels of target.

Neo-X-Prime[A1] [A2] is a platform based on bispecific conditional CD40 agonistic antibodies that target TAAs expressed at high densities, where the lead program, ATOR-4066, targets CD40 and CEA. We have demonstrated that Neo-X-Prime bsAbs enable a novel mode of action involving delivery of tumor antigens to DCs and increased priming of tumor-specific T cells, which results in increased anti-tumor efficacy compared to monoclonal antibodies.

First-generation CD137 agonists haven’t reached desirable clinical outcomes due to hepatotoxicity and/or poor efficacy. With “fit-for-purpose” design, NovaRock developed a CD137 bispecific platform to activate the co-stimulatory pathway through TAA-mediated receptor clustering. These bispecific antibodies reprogram the tumor microenvironment to elicit potent anti-tumor effects without detectable toxicity and long-lasting immunological memory. Additionally, these antibodies have been optimized to facilitate development and manufacturing. The lead antibody is currently in IND-enabling stage.