Antibody-Dependent Cellular Cytotoxicity Activity of a Novel Anti–PD-L1 Antibody Avelumab (MSB0010718C) on Human Tumor Cells

Abstract

Several anti-PD1/PD-L1 monoclonal antibodies (MAb) are currently providing evidence of clinical benefit in subsets of cancer patients. The mode of action of these MAbs is to inhibit PD1 on immune cells interacting with PD-L1 on tumor cells. These MAbs are either designed or engineered to eliminate antibody-dependent cell-mediated cytotoxicity (ADCC), which, however, has been implicated as an important mechanism in several highly effective MAb-mediated cancer therapies. A fully human anti-PD-L1 MAb would potentially be able to block PD-L1/PD1 interactions and also mediate the ADCC lysis of tumor cells. MSB0010718C (designated avelumab) is a fully human IgG1 anti-PD-L1 MAb. The studies reported here demonstrate (a) the ability of avelumab to lyse a range of human tumor cells in the presence of PBMC or NK effectors; (b) IFNγ can enhance tumor cell PD-L1 expression and in some cases enhance ADCC tumor cell lysis; (c) purified NK cells are potent effectors for avelumab; (d) similar levels of avelumab-mediated ADCC lysis of tumor cells are seen using purified NK as effectors from either healthy donors or cancer patients; (e) very low levels of avelumab-mediated lysis are seen using whole PBMCs as targets; this finding complements results seen in analyses of PBMC subsets of patients receiving avelumab; and (f) the addition of IL12 to NK cells greatly enhances avelumab-mediated ADCC. These studies thus provide an additional mode of action for an anti-PD-L1 MAb and support the rationale for further studies to enhance avelumab-mediated ADCC activity.

A novel bispecific antibody for EGFR-directed blockade of the PD-1/PD-L1 immune checkpoint

“…28 , 29 However, human IgG1 containing avelumab was shown to have a toxicity profile comparable to ADCC-null PD-L1-blocking antibodies 30-32 with low levels of lysis of PBMCs in vitro . 27 , 33 Moreover, NK cell-mediated ADCC by avelumab was shown to enhance its therapeutic functionality. 33 , 34 Similarly, the human IgG1 domain present in PD-L1xEGFR may enhance its therapeutic activity as it promotes NK cell-mediated ADCC towards EGFR-expressing cancer cells.…”

“…27 , 33 Moreover, NK cell-mediated ADCC by avelumab was shown to enhance its therapeutic functionality. 33 , 34 Similarly, the human IgG1 domain present in PD-L1xEGFR may enhance its therapeutic activity as it promotes NK cell-mediated ADCC towards EGFR-expressing cancer cells.…”

“…Sorted NK cells (1 × 10 6 cells/ml) were stimulated using in RPMI-1640/FBS medium supplemented with IL-12 (10 ng/ml) for 24 h as described previously. 33 NK cells were washed with PBS and then mixed with cancer cells at the indicated E to T ratios and treated with PD-L1xEGFR, PD-L1xMock or appropriate control antibodies (each 5 µg/ml). After 18 h of treatment, apoptosis was assessed by flow cytometry using Annexin-V staining.…”

Epigenetic priming of both tumor and NK cells augments antibody-dependent cellular cytotoxicity elicited by the anti-PD-L1 antibody avelumab against multiple carcinoma cell types

“…33 In addition, tumor cells can be eliminated by NK cells through antibody-dependent cellular cytotoxicity (ADCC) if the proper IgG1 monoclonal antibody (mAb) target is present on the surface of tumor cells. 34–39 We have previously reported the ability of avelumab to mediate the lysis of a range of human carcinomas in vitro by ADCC in the presence of peripheral blood mononuclear cells (PBMCs) or NK cell effectors. 34,39 …”

“…34–39 We have previously reported the ability of avelumab to mediate the lysis of a range of human carcinomas in vitro by ADCC in the presence of peripheral blood mononuclear cells (PBMCs) or NK cell effectors. 34,39 …”