Ipilimumab and Its Derived EGFR Aptamer-Based Conjugate Induce Efficient NK Cell Activation against Cancer Cells

Abstract

The immune checkpoint CTLA-4 (cytotoxic T-lymphocyte-antigen 4), which inhibits the co-stimulatory CD28 signal on T cells, has been recently found expressed on other cell populations, such as tumor and natural killer (NK) cells. We tested for the first time the effects of ipilimumab, the human anti-CTLA4 mAb in clinical use, on these cells and found that it inhibits the growth of tumor cells expressing CTLA-4 also in the absence of lymphocytes, and efficiently activates NK cells, thus suggesting an important unexplored role of NK cells in ipilimumab-modulated immune responses. Interestingly, the epidermal growth factor receptor (EGFR) has been shown to play a key role in tumor cell escape from immune surveillance, and in cytotoxic T lymphocyte inhibition. Thus, we tested combinatorial treatments of ipilimumab with an anti-EGFR aptamer endowed with anti-tumor activity, and constructed for the first time a novel bispecific immunoconjugate, made up of these two compounds. The novel immunoconjugate binds to the target cells, induces the activation of lymphocytes, including NK cells, and inhibits the growth of tumor target cells more efficiently than the parental compounds, by strongly enhancing the cytotoxic activity of both human peripheral blood mononuclear cells and NK cells against tumor cells.

NLRP3 as Putative Marker of Ipilimumab-Induced Cardiotoxicity in the Presence of Hyperglycemia in Estrogen-Responsive and Triple-Negative Breast Cancer Cells

“…Although many immortalized cell lines may have a reduced HLA expression [ 65 , 66 , 67 ], it is conceivable that some cancer cells induce an HLA mismatch when co-incubated with hPBMCs, being from different donors. However, in line with other similar papers published in the literature [ 61 , 62 , 63 , 64 ], for all tested combinations (in our case controls and treatments with ipilimumab under high glucose and low glucose) the differences between groups are still due to the treatment conditions. Moreover, different open discussion papers are available about the role, for example, of HLA-E in co-cultures of cancer cells and PBMCs [ 68 ].…”

“…There are some limitations of this study: firstly, human leukocyte antigen (HLA)-class I molecules on tumor cells have been regarded as crucial sites where cytotoxic T lymphocytes can recognize tumor-specific antigens. HLA mismatch could be a possible limitation of co-cultures of tumor cells with hPMBCs, despite co-culture models often being used and recommended in preliminary cell-lymphocytes interaction studies, as reported in the literature [ 61 , 62 , 63 , 64 ]. Although many immortalized cell lines may have a reduced HLA expression [ 65 , 66 , 67 ], it is conceivable that some cancer cells induce an HLA mismatch when co-incubated with hPBMCs, being from different donors.…”

Transfer learning between preclinical models and human tumors identifies conserved NK cell activation signature in anti-CTLA-4 responsive tumors

“…In melanoma patients treated with anti-CTLA-4, a higher percentage of circulating mature NK cells is correlated with improved overall survival, and NK cells isolated from responsive patients have increased cytolytic activity compared to NK cells isolated from non-responders (Tallerico et al, 2017). A very recent study also showed that an anti-CTLA-4-EGFR immunoconjugate enhances the in vitro lysis of breast cancer cells by NK cells (Passariello et al, 2020). In B16 melanoma models, NK cells and CD8+ T cells synergistically clear tumors in response to anti-CTLA-4 and IL-2 treatment (Kohlhapp et al, 2015).…”

Aptamer targeted therapy potentiates immune checkpoint blockade in triple-negative breast cancer

“…antibody covalently linked to Gint4.T aptamer, thus optimizing the e cacy of the combination therapy by increasing their co-targeting at the tumor site while dispensing lower doses of either single agents and overcoming the limits related to the rapid clearance of the aptamers. We previously developed three different bispeci c conjugates consisting of EGFR aptamer linked to either anti-HER2, anti-PD-L1 or anti-CTLA-4 mAbs [38,39]. By this strategy the advantages of Gint4.T aptamer (nuclease resistance, rapid tumor uptake, durable tumor retention [31] and anti-PD-L1 antibodies (longer half-life in circulation, immunomodulatory activity) could be combined in one single molecule with improved therapeutic effectiveness and pharmacokinetic/pharmacodynamic properties over the parental moieties.…”

“…For determination of tumor cell lysis, the release of lactate dehydrogenase (LDH) in the cellular co-culture supernatants was measured by a LDH detection kit (Thermo sher Scienti c, Meridian Rd., Rockoford, IL, USA), as previously described [38,39].…”