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

Abstract

PD-L1-blocking antibodies produce significant clinical benefit in selected cancer patients by reactivating functionally-impaired antigen-experienced anticancer T cells. However, the efficacy of current PD-L1-blocking antibodies is potentially reduced by ‘on-target/off-tumor’ binding to PD-L1 widely expressed on normal cells. This lack of tumor selectivity may induce a generalized activation of all antigen-experienced T cells which may explain the frequent occurrence of autoimmune-related adverse events during and after treatment.To address these issues, we constructed a bispecific antibody (bsAb), designated PD-L1xEGFR, to direct PD-L1-blockade to EGFR-expressing cancer cells and to more selectively reactivate anticancer T cells. Indeed, the IC50 of PD-L1xEGFR for blocking PD-L1 on EGFR+ cancer cells was ∼140 fold lower compared to that of the analogous PD-L1-blocking bsAb PD-L1xMock with irrelevant target antigen specificity. Importantly, activation status, IFN-γ production, and oncolytic activity of anti-CD3xanti-EpCAM-redirected T cells was enhanced when cocultured with EGFR-expressing carcinoma cells. Similarly, the capacity of PD-L1xEGFR to promote proliferation and IFN-γ production by CMVpp65-directed CD8+ effector T cells was enhanced when cocultured with EGFR-expressing CMVpp65-transfected cancer cells. In contrast, the clinically-used PD-L1-blocking antibody MEDI4736 (durvalumab) promoted T cell activation indiscriminate of EGFR expression on cancer cells. Additionally, in mice xenografted with EGFR-expressing cancer cells 111In-PD-L1xEGFR showed a significantly higher tumor uptake compared to 111In-PD-L1xMock. In conclusion, PD-L1xEGFR blocks the PD-1/PD-L1 immune checkpoint in an EGFR-directed manner, thereby promoting the selective reactivation of anticancer T cells. This novel targeted approach may be useful to enhance efficacy and safety of PD-1/PD-L1 checkpoint blockade in EGFR-overexpressing malignancies.

The yin and yang of co-inhibitory receptors: toward anti-tumor immunity without autoimmunity

“…Also noteworthy is a growing body of research focused on novel tumor-restricted immunotherapy strategies beyond the scope of this review. These promising approaches include: (i) Vaccines targeting neoantigens [259][260][261] ; (ii) Chimeric antigen receptor (CAR) T-cell therapy 262 ; (iii) Improved delivery of checkpoint blockade antibodies within the TME; (iv) Bispecific antibodies [263][264][265] ; and (v) Molecular shields restricting local activity of checkpoint inhibitors. 266 For future research, we propose studies designed to identify novel regulatory molecules that, when targeted, simultaneously enhance anti-tumor immunity yet suppress autoimmunity.…”

Tumor-targeting anti-EGFR x anti-PD1 bispecific antibody inhibits EGFR-overexpressing tumor growth by combining EGFR blockade and immune activation with direct tumor cell killing

“…In this study, we devised a strategy to combine conventional targeted therapy with immune checkpoint blockade (anti-PD1/PDL1) by a BsAb approach to treat solid tumors. In the BsAb embodiment, the anti-PD1 antibody is directed to the tumor microenvironment by a second antibody targeting a tumor associated antigens expressed in the tumors [29] . The BsAb, anti-PD1 x EGFR BsAb, was constructed by fusion of two anti-PD1 scFv symmetrically to the N-terminus of the heavy chains of cetuximab.…”

“…There are in theory several rationales for co-targeting EGFR on tumor cells and PD1 on T cells via a BsAb: 1) accumulating evidence demonstrated that stimulation of EGFR signaling can suppress immune responses and enhance the tumor cell evasion of immune surveillance, including induction of PDL-1 overexpression on the surface of tumor cells, stimulation of VEGF, IL6, IL10 secretion, activation of regulatory T cells (Tregs) and downregulation of T cell chemokines [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] . Inhibition of EGFR signaling in tumor cells, therefore, not only can exert direct antitumor activity but also may create a more favorable anti-tumor immune microenvironment [40 , 46] ; 2) By targeting EGFR-overexpressing tumor cells, anti-PD1 x EGFR BsAb may enhance the antibody localization to specifically target and activate T cells and other immune cells within the tumor microenvironment [29] ; 3) the BsAb simultaneously targeting EGFR on tumor cell surface and PD1 on T cells may likely be able to create direct cell-cell interaction/engagement of the tumor cells and the immune cells, and leads to the formation of immunological synapse, resulting in CD8 + T cell activation and potent tumor cell killing [30 , 47] .…”

“…Novel mAb to other immune checkpoint targets, for example antagonistic antibodies to LAG3, TIM3 and TIGIT, and agonistic antibodies to CD40, OX40 and 4-1BB, are being identified and developed [27 , 28] . Anti-EGFR antibody-based bispecific antibodies (BsAb) and antibody-drug conjugates (ADC) are also being studied [29 – 31] . Recently, combination therapies of two or more tumor-targeting mAbs, for example, anti-HER2 mAbs, trastuzumab and pertuzumab, in breast cancer, or two or more immune checkpoint inhibitor mAbs, for instance, an anti-PD1 mAb (nivolumab) and an anti-CTLA4 mAb (ipilimumab) in melanoma and NSCLC, or others, such as an anti-vascular endothelial growth factor (VEGF) mAb (bevacizumab) and an anti-PDL1 mAb (atezolizumab) in liver cancer, have been shown to be more efficacious than single antibody agents in the clinic [32 , 33] .…”

A Comprehensive Data Analysis of Differentially Regulated Genes in Melanoma

“…For instance, EGFR, as an essential receptor of transforming growth factor alpha, has attracted widespread attention. Previous studies have found that the frequency of oncogenic mutations in the EGFR gene is closely related to the occurrence of melanoma [29][30][31]. In addition, EGFR has been proposed as an important molecular target for the treatment of cancer, which has promoted the development of EGFR pharmacological inhibitors [32,33].…”