T cell bispecific (TCB) antibodies are potent molecules that are transforming the treatment of human cancers. Whereas increased intra-tumor T cell infiltration following TCB treatment has been vastly documented, the information about the additional changes in the tumor microenvironment (TME), and the involvement of the other immune cells remains elusive. We conducted a high dimensional single-cell analysis of TCB-treated tumors to characterize the TME reprogramming upon TCB treatment.

Monoclonal antibodies for cancer treatment are designed of the IgG class. IgE, an antibody class known to exert immunological effects in tissues through very high affinity for cognate Fcε receptors, may activate immune cells against tissue-resident tumours. We demonstrated that IgEs directed against cancer antigens kill tumours by harnessing known immunological mechanisms naturally employed in parasite clearance. IgE potentiated macrophage recruitment and promoted pro-inflammatory macrophage phenotypes in the tumour microenvironment.

OxMIF, the disease-related isoform of macrophage migration inhibitory factor (MIF), is present in the tumor microenvironment and in inflamed tissues. We have developed 2nd-generation anti-oxMIF antibodies with improved physicochemical properties which demonstrated efficacy in models of cancer and inflammation. These antibodies have great potential for the treatment of solid tumors (ON203) and inflammatory diseases (ON104), either as monotherapy or in rational combinations, e.g. with checkpoint inhibitors or glucocorticoids, respectively.

Myeloid cells such as monocytes/macrophages and PMN can kill tumor cells in the presence of tumor-directed antibodies. Switching to antibodies of human IgA isotype improved tumor cell lysis, in particular by PMN, which is further enhanced by myeloid checkpoint blockade, e.g., with CD47 antibodies. Novel antibody engineering technologies bring IgA antibodies closer to clinical development. Thus, the future challenge will be to identify situations in which myeloid effector cells can optimally contribute to antibody efficacy.

The identification and validation of novel myeloid immune checkpoint targets and development of their antagonists is an exciting innovation in cancer immunotherapy to bridge the innate and adaptive immune systems. The presentation will focus on how the SIRPα-CD47 axis stimulates macrophages to recruit the adaptive immune arm via chemoattraction, and inhibition of this pathway may avoid T cell exclusion in synergy with T cell immune checkpoint and clinical translation. Emerging targets such as the C-type lectin receptor CLEC1 regulating dendritic cell cross-presentation properties will be discussed too.

Despite the discovery of the human leukocyte immunoglobulin (Ig)-like receptor (LILR) family in the late 1990s, the functions of many of these receptors remain unclear. Moreover, rodents do not express LILR homologous, making it difficult to study their function. We and others have generated specific monoclonal antibodies and relevant preclinical models, which have provided an invaluable platform to study the function of inhibitory LILRs (LILRBs). It is expected that blocking the function of LILRBs can skew the function of myeloid cells towards a pro-inflammatory and anti-tumour phenotype.

Agonistic antibodies directed to immunostimulatory receptors are a currently untapped source for immunotherapy. Whereas checkpoint blockers have translated into the clinic, the rules for agonistic immunostimulatory antibodies have been more difficult to discern and these reagents await further optimisation. Here we discuss the salient properties of monoclonal antibodies (mAb) required to strongly agonise these receptors and discuss potential strategies for engineering more effective therapeutics in the future.

I will describe how localized 4-1BB agonism supports T cell activation without systemic side effects. Cinrebafusp alfa (PRS-343), a bispecific fusion protein that combines a 4-1BB-targeting Anticalin protein and a HER2-targeting antibody, has shown both clinical benefit linked to a 4-1BB mechanism of action, and robust durability. It has been observed to be safe and well-tolerated.

The role of Tregs in glioblastoma remains controversial and their depletion has the potential to open the door to new treatment strategies for this devastating disease. By combining the analysis of human datasets, the use of a novel Treg targeting antibody and a newly developed mouse model of glioblastoma we have found that Treg depletion leads to deep changes in the adaptive and innate compartments allowing for the rational design of novel combination therapies targeting the glioblastoma microenvironment.

A lead Neo-X-Prime candidate drug (ATOR-4066), targeting CD40 and CEA, has been engineered and shown to have optimal functional and safety properties. Further, data with concept molecules demonstrate that Neo-X-Prime bsAbs enable a unique mode of action involving delivery of neoantigens to DCs and priming of neoantigen-specific T cells, which results in increased anti-tumor efficacy compared to CD40 monoclonal antibodies and present a promising approach to overcome PD-1 resistance.

Treatment with immune checkpoint blocking (ICB) antibodies results in long-lasting antitumor responses in diverse cancers. Currently available approaches to ICB, however, are ineffective in treating patients with poorly immune-infiltrated, cold, tumors. This talk will discuss how intra-tumoral administration of a novel, oncovirally-encoded, Treg-depleting anti-CTLA-4 antibody, may help overcome the resistant tumor microenvironment, to bring clinical benefit to patients with cold tumors. Following demonstrated in vivo proof-of-concept, vectorized aCTLA-4 (BT-001) is now in clinical testing.

This talk will describe the discovery and biological characterisation of GSK6097608 which targets the inhibitory immune receptor CD96. We used the yeast based Adimab platform for rapid discovery and subsequent selection of higher affinity variants. GSK6097608 can block CD155 binding and compete off bound CD155 from CD96. We explored different Fc regions and demonstrated that wild type Fc is required for its activity and showed Fc-dependent potentiation of both primary human T and NK cells. CD96 is part of the CD226 axis which plays a role in regulating NK and T cells in tumor immunology.

Treg cells inhibit immune responses in cancers using cell-cell contacts and anti-inflammatory cytokines. Due to high and constitutive levels of IL2Ra chain (CD25) expression, tumor infiltrating (TIL)-Tregs cells preferably consume local Interleukin-2 (IL2), thus depriving conventional T cells from IL2-induced activation and proliferation. Therefore, the selective depletion of TIL-Tregs using antibodies targeting CD25 while sparing conventional T cells represents a promising strategy to unleash tumor-specific immune responses in solid cancers.

The tumour microenvironment is complex and heterogenous and likely a key determinant of response to immunotherapy. Understanding its complexity in patients and modelling this in preclinical studies will likely be critical to enhancing outcomes. Here, we will demonstrate how environment can impact immunomodulatory mAb mechanisms of action and efficacy, and ways we can better model the complexity of human cancers to deliver findings that can be taken to the clinic.

Antibody Fc engagement with the inhibitory Fc RIIb receptor has potential therapeutic applications in clearance of soluble targets, enhanced agonism of TNFR superfamily members, B-cell silencing, and other diverse areas. We describe the use of computational protein design combined with the Azymetric Fc heterodimer platform to develop a family of Fc RIIb-selective Fc regions with a range of affinities that modulate in vitro and in vivo functional activity across multiple antibody systems.