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Simple Summary: TCR-mimics (TCRm) are designed to target intracellular tumor antigens presented by major histocompatibility complex (MHC) molecules on the surface of cancer cells. A TCRm imitates the capacity of T cells receptors (TCR) interact with peptide-MHC complexes (pMHC) to reach a broad range of intracellular targets with the unique strengths of high affinity and specificity of antibodies. This capability allows them to tackle previously "undruggable" targets for therapeutics when TCRm is engineered into different mechanisms of action like TCE or ADC. Effectively targeting intracellular tumor-associated proteins presents a formidable challenge in oncology, as they are traditionally considered inaccessible to conventional antibody-based therapies and CAR-T cell therapies. However, recent advancements in antibody engineering have revolutionized this field, offering promising new strategies to combat cancer. This review focuses on the innovative use of T-cell receptor mimic (TCRm) antibodies within the therapeutic frameworks of T-cell engagers (TCE) and antibody-drug conjugates (ADCs). TCRm antibodies, designed to recognize peptide-MHC complexes rather than cell surface proteins, integrate the capacity of T-cells to reach intracellular targets with the unique strengths of antibodies. When incorporated into T-cell engaging therapeutics, TCRms redirect T cells to cancer cells, facilitating direct cytotoxicity. In ADCs, TCRm antibodies deliver cytotoxic agents with highly specific targeting to cancer cells, sparing healthy tissues. Together, these antibody-based strategies represent a significant leap forward in oncology, opening new avenues for the treatment of cancers previously deemed untreatable, with other potential applications in autoimmune diseases. This review discusses the mechanisms, clinical advancements, and future prospects of these cutting-edge therapies, highlighting their potential to transform the landscape of cancer treatment. [ABSTRACT FROM AUTHOR]

As the fastest growing class of therapeutic proteins, monoclonal antibodies (mAbs) represent a major potential drug class. Human antibodies are glycosylated in their native state and all clinically approved mAbs are produced by mammalian cell lines, which secrete mAbs with glycosylation structures that are similar, but not identical, to their human counterparts. Glycosylation of mAbs influences their interaction with immune effector cells that kill antibody-targeted cells. Here we demonstrate that human antibodies with specific human N-glycan structures can be produced in glycoengineered lines of the yeast Pichia pastoris and that antibody-mediated effector functions can be optimized by generating specific glycoforms. Glycoengineered P. pastoris provides a general platform for producing recombinant antibodies with human N-glycosylation. [ABSTRACT FROM AUTHOR]

State-of-the-art monoclonal antibody (mAb) discovery methods that utilize surface display techniques in prokaryotic and eukaryotic cells require multiple steps of reformatting and switching of hosts to transition from display to expression. This results in a separation between antibody affinity maturation and full-length mAb production platforms. Here, we report for the first time, a method in Glyco-engineered Pichia pastoris that enables simultaneous surface display and secretion of full-length mAb molecules with human-like N-glycans using the same yeast cell. This paradigm takes advantage of homo-dimerization of the Fc portion of an IgG molecule to a surface-anchored "bait" Fc, which results in targeting functional “half” IgGs to the cell wall of Pichia pastoris without interfering with the secretion of full length mAb. We show the utility of this method in isolating high affinity, well-expressed anti-PCSK9 leads from a designed library that was created by mating yeasts containing either light chain or heavy chain IgG libraries. Coupled with Glyco-engineered Pichia pastoris, this method provides a powerful tool for the discovery and production of therapeutic human mAbs in the same host thus improving drug developability and potentially shortening the discovery time cycle. [ABSTRACT FROM AUTHOR]

The methylotrophic yeast, Pichia pastoris, is an important organism used for the production of therapeutic proteins. However, the presence of fungal-like glycans, either N-linked or O-linked, can elicit an immune response or enable the expressed protein to bind to mannose receptors, thus reducing their efficacy. Previously we have reported the elimination of β-linked glycans in this organism. In the current report we have focused on reducing the O-linked mannose content of proteins produced in P. pastoris, thereby reducing the potential to bind to mannose receptors. The initial step in the synthesis of O-linked glycans in P. pastoris is the transfer of mannose from dolichol-phosphomannose to a target protein in the yeast secretory pathway by members of the protein-O-mannosyltransferase (PMT) family. In this report we identify and characterize the members of the P. pastoris PMT family. Like Candida albicans, P. pastoris has five PMT genes. Based on sequence homology, these PMTs can be grouped into three sub-families, with both PMT1 and PMT2 sub-families possessing two members each (PMT1 and PMT5, and PMT2 and PMT6, respectively). The remaining sub-family, PMT4, has only one member (PMT4). Through gene knockouts we show that PMT1 and PMT2 each play a significant role in O-glycosylation. Both, by gene knockouts and the use of Pmt inhibitors we were able to significantly reduce not only the degree of O-mannosylation, but also the chain-length of these glycans. Taken together, this reduction of O-glycosylation represents an important step forward in developing the P. pastoris platform as a suitable system for the production of therapeutic glycoproteins. [ABSTRACT FROM AUTHOR]

State-of-the-art monoclonal antibody (mAb) discovery methods that utilize surface display techniques in prokaryotic and eukaryotic cells require multiple steps of reformatting and switching of hosts to transition from display to expression. This results in a separation between antibody affinity maturation and full-length mAb production platforms. Here, we report for the first time, a method in Glyco-engineered Pichia pastoris that enables simultaneous surface display and secretion of full-length mAb molecules with human-like N-glycans using the same yeast cell. This paradigm takes advantage of homo-dimerization of the Fc portion of an IgG molecule to a surface-anchored "bait" Fc, which results in targeting functional “half” IgGs to the cell wall of Pichia pastoris without interfering with the secretion of full length mAb. We show the utility of this method in isolating high affinity, well-expressed anti-PCSK9 leads from a designed library that was created by mating yeasts containing either light chain or heavy chain IgG libraries. Coupled with Glyco-engineered Pichia pastoris, this method provides a powerful tool for the discovery and production of therapeutic human mAbs in the same host thus improving drug developability and potentially shortening the discovery time cycle. [ABSTRACT FROM AUTHOR]

While yeast are lower eukaryotic organisms, they share many common features and biological processes with higher eukaryotes. As such, yeasts have been used as model organisms to facilitate our understanding of such features and processes. To this end, a large number of powerful genetic tools have been developed to investigate and manipulate these organisms. Going hand-in-hand with these genetic tools is the ability to efficiently scale up the fermentation of these organisms, thus making them attractive hosts for the production of recombinant proteins. A key feature of producing recombinant proteins in yeast is that these proteins can be readily secreted into the culture supernatant, simplifying any downstream processing. A consequence of this secretion is that the proteins typically pass through the secretory pathway, during which they may be exposed to various posttranslational modifications. The addition of glycans is one such modification. Unfortunately, while certain aspects of glycosylation are shared between lower and higher eukaryotes, significant differences exist. Over the last two decades much research has focused on engineering the glycosylation pathways of yeast to more closely resemble those of higher eukaryotes, particularly those of humans for the production of therapeutic proteins. In the current review we shall highlight some of the key achievements in yeast glyco-engineering which have led to humanization of both the N- and O-linked glycosylation pathways.

Currently, mammalian cells are the most commonly used hosts for the production of therapeutic monoclonal antibodies (mAbs). These hosts not only secrete mAbs with properly assembled two heavy and two light chains but also deliver mAbs with a glycosylation profile that is compatible with administration into humans. GlycoFi, a wholly owned subsidiary of Merck & Co., Inc., humanized the Pichia glycosylation pathway which allows it to express glycoproteins with a human-like glycan profile. This offers an alternative mAb production platform similar to mammalian hosts and in some cases it even provides more homogenous product and better efficacy, such as enhanced effector function. This chapter describes a protocol for using glycoengineered Pichia to produce full-length mAbs. It covers a broad spectrum of mAb expression technologies in yeast including expression vector construction, yeast transformation, high-throughput strain selection to fermentation, and antibody purification.