TCR-like antibody duocarmycin conjugates promote cytotoxicity of tumor cells expressing low peptide/HLA targets

Abstract

Immunotherapeutic strategies such as unmodified antibodies have significantly advanced treatment options for individuals with cancer. Yet, to further improve the efficacy of this approach, engineered platforms such as antibody drug conjugates (ADCs) are under development. Current FDA-approved ADC designs incorporate tubulin inhibitors that abate cancer growth and mediate clinical protection for patients. However, successful ADC treatment typically requires high tumor antigen (TA) surface expression to bind/internalize ADC material, destabilize cytoskeletal networks, and suppress tumorigenesis. Unfortunately, few known TAs are localized on cancer cells at elevated densities, potentially minimizing the therapeutic index and widespread application of current ADC regimens. Our group sought to overcome this ADC limitation of TA expression by crosslinking the DNA alkylating compound duocarmycin with T cell receptor (TCR)-like antibodies, which specifically bind TA peptide/human leukocyte antigen (HLA) complexes analogous to a TCR. In select assays, a panel of TCR-like ADCs were capable of distinguishing human breast and colon cancer lines and promoting potent cell cytotoxicity even under common scenarios of low TA peptide/HLA densities. Additionally, TCR-like antibody TA peptide/HLA binding appeared to play an important role in ADC-mediated cytotoxicity, supporting the notion that spatial TA ligand interactions influence ADC function. Overall, our data highlight the proof-of-principle that TCR-like ADCs induce cancer cell death under physiologically-relevant TA expression profiles and support their translational development, particularly alongside agents that disrupt DNA replication.

Detection of specific antibody-ligand interactions with a self-induced back-action actuated nanopore electrophoresis sensor

“…For example, the SANE sensor could be useful for the screening of T-cell receptor-like antibodies that bind with high affinity to pMHCs, like the RAH antigen, that are presented on the surface of cancer cells [46]. When used in vivo, the binding of such antibodies can be the first step towards helping the immune system mount a response against the cancer [40][41][42][43][44]. The availability of pMHC ligand amounts that can be isolated from tissue biopsy is limited and therefore the SANE sensor-enabled savings of pMHC ligand amounts could enable testing several antibodies to select the best candidate to target a particular tumor.…”

“…This work goes beyond nanoparticle trapping to demonstrate the feasibility of using the SANE sensor for the identification of antibodies, their ligands and the complexes they form, while also distinguishing between specific and non-specific binding. Importantly, the proteins used in this proof-of-principle study are of biological relevance, representing a simplified free-solution model of peptide-presenting major histocompatibility complex (pMHC) ligand [40][41][42] interactions with T-cell receptor-like monoclonal antibodies (TCRmAbs) [43,44]. When deployed in vivo, TCRmAbs can provide a possible approach to cancer immunotherapy as they could help elicit a systemic immune response against cancer cells presenting specific pMHCs that are absent in normal cells [40][41][42][43][44].…”

“…Importantly, the proteins used in this proof-of-principle study are of biological relevance, representing a simplified free-solution model of peptide-presenting major histocompatibility complex (pMHC) ligand [40][41][42] interactions with T-cell receptor-like monoclonal antibodies (TCRmAbs) [43,44]. When deployed in vivo, TCRmAbs can provide a possible approach to cancer immunotherapy as they could help elicit a systemic immune response against cancer cells presenting specific pMHCs that are absent in normal cells [40][41][42][43][44]. This work tested the ability of the SANE sensor to distinguish between specific binding for a TCRmAb, engineered to target with high affinity (nM) a cancer-relevant pMHC, and the non-specific binding of a cancer-irrelevant TCRmAb to the same pMHC ligand.…”