A VEGFR2-MICA bispecific antibody activates tumor-infiltrating lymphocytes and exhibits potent anti-tumor efficacy in mice

Controversial role of γδ T cells in colorectal cancer

Colorectal cancer (CRC) is the third most frequent type of cancer, and the second leading cause of cancer-related deaths worldwide. Current treatments for patients with CRC do not substantially improve the survival and quality of life of patients with advanced CRC, thus necessitating the development of new treatment strategies. The emergence of immunotherapy has revitalized the field, showing great potential in advanced CRC treatment. Owing to the ability of tumor cells to evade the immune system through major histocompatibility complex shedding and heterogeneous and low antigen spreading, only a few patients respond to immunotherapy. γδ T cells have heterogeneous structures and functions, and their key roles in immune regulation, tumor immunosurveillance, and specific primary immune responses have increasingly been recognized. γδ T cells recognize and kill CRC cells efficiently, thus inhibiting tumor progress through various mechanisms. However, γδ T cells can potentially promote tumor development and metastasis. Thus, given this dual role in prognosis, these cells can act as either a "friend" or "foe" of CRC. In this review, we explore the characteristics of γδ T cells and their functions in CRC, highlighting their application in immunotherapy.

Enhanced antitumor and anti-metastasis by VEGFR2-targeted doxorubicin immunoliposome synergy with NK cell activation

Liposomal doxorubicin exhibits stronger drug accumulation at the tumor site due to the Enhanced Permeability and Retention (EPR) effect. However, the prognosis for the patient is poor due to this drug's lack of targeting and tumor metastasis during treatment. Vascular epidermal growth factor receptor (VEGFR2) plays an important role in angiogenesis and cancer metastasis. To enhance antitumor efficacy of PEGylated liposomal doxorubicin, we constructed a VEGFR2-targeted and doxorubicin-loaded immunoliposome (Lipo-DOX-C00) by conjugating a VEGFR2-specific, single chain antibody fragment to DSPE-PEG2000-MAL, and then we inserted the antibody-conjugated polymer into liposomal doxorubicin (Lipo-DOX). The immunoliposome was formed uniformly with high affinity for VEGFR2. In vitro, Lipo-DOX-C00 enhanced doxorubicin internalization into LLC and 4T1 cells compared with non-conjugated, liposomal doxorubicin. In vivo, Lipo-DOX-C00 delivered DOX to tumor tissues effectively, which exhibited an improved antitumor and anti-metastasis efficacy in both LLC subcutaneous tumor models and 4T1 tumor models. In addition, the combined therapy of a VEGFR2-MICA bispecific antibody (JZC01) and Lipo-DOX-C00 achieved enhanced inhibition of cancer growth and metastasis due to activation of the immune system. Our study provides a promising approach to clinical application of liposomal doxorubicin.

αVEGFR2-MICA fusion antibodies enhance immunotherapy effect and synergize with PD-1 blockade

Antiangiogenic therapy has shown significant clinical benefits in gastric cancer (GC) and non-small cell lung cancer (NSCLC). However, their effectiveness is limited by the immunosuppressive tumor microenvironment. The MHC class I chain-related molecules A and B (MICA/B) are expressed in many human cancers, enabling elimination of cancer cells by cytotoxic lymphocytes through natural killer group 2D (NKG2D) receptor activation. To improve antiangiogenic therapy and prolong its efficacy, we generated a bi-specific fusion protein (mAb04-MICA). This was comprised of an antibody targeting VEGFR2 fused to a MICA α1-α2 ectodomain. mAb04-MICA inhibited proliferation of GC and NSCLC cells through specific binding to VEGFR2 and had superior anti-tumor efficacy in both GC and NSCLC-bearing mouse models compared with ramucirumab. Further investigation revealed that the mAb04-MICA promoted NKG2D⁺ NK cell activation and induced the tumor-associated macrophage (TAM) polarization from M2 type to M1 type both in vitro and in vivo. The polarization of TAMs upon NKG2D and MICA mediated activation has not yet been reported. Moreover, given the up-regulation of PD-L1 in tumors during anti-angiogenesis therapy, anti-PD-1 antibody enhanced the anti-tumoral activity of mAb04-MICA through stimulating infiltration and activation of NKs and CD8⁺T cells in responding tumors. Our findings demonstrate that dual targeting of angiogenesis and NKG2D, or in combination with the PD-1/PD-L1 blockade, is a promising anti-tumor therapeutic strategy. This is accomplished through maintaining or reinstating tumor immunosurveillance during treatment, which expands the repertoire of anti-angiogenesis-based cancer immunotherapies.

Functional antibody characterization via direct structural analysis and information-driven protein-protein docking

Detailed description of the mechanism of action of the therapeutic antibodies is essential for the functional characterization and future optimization of potential clinical agents. We recently developed KD035, a fully human antibody targeting vascular endothelial growth factor receptor 2 (VEGFR2). KD035 blocked VEGF‐A, and VEGF‐C‐mediated VEGFR2 activation, as demonstrated by the in vitro binding and competition assays and functional cellular assays. Here, we report a computational model of the complex between the variable fragment of KD035 (KD035(Fv)) and the domains 2 and 3 of the extracellular portion of VEGFR2 (VEGFR2(D2‐3)). Our modeling was guided by a priori experimental information including the X‐ray structures of KD035 and related antibodies, binding assays, target domain mapping and comparison of KD035 affinity for VEGFR2 from different species. The accuracy of the model was assessed by molecular dynamics simulations, and subsequently validated by mutagenesis and binding analysis. Importantly, the steps followed during the generation of this model can set a precedent for future in silico efforts aimed at the accurate description of the antibody–antigen and more broadly protein–protein complexes.

Targeting MICA/B with cytotoxic therapeutic antibodies leads to tumor control

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

Targeting MICA/B with cytotoxic therapeutic antibodies leads to tumor control

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

Predictive Values of Programmed Cell Death-Ligand 1 Expression for Prognosis, Clinicopathological Factors, and Response to Programmed Cell Death-1/Programmed Cell Death-Ligand 1 Inhibitors in Patients With Gynecological Cancers: A Meta-Analysis

Background

The prognostic value of programmed cell death-ligand 1 (PD-L1) in gynecological cancers has been explored previously, but the conclusion remains controversial due to limited evidence. This study aimed to conduct an updated meta-analysis to re-investigate the predictive significance of PD-L1 expression.

Methods

PubMed, EMBASE and Cochrane Library databases were searched. The associations between PD-L1 expression status and prognosis [overall survival (OS), progression-free survival (PFS), recurrence-free survival (RFS), cancer-specific survival (CSS) or disease-free survival (DFS)], clinical parameters [FIGO stage, lymph node metastasis (LNM), tumor size, infiltration depth, lymphovascular space invasion (LVSI) or grade] and response to anti-PD-1/PD-L1 treatment [objective response rate (ORR)] were analyzed by hazard ratios (HR) or relative risks (RR).

Results

Fifty-five studies were enrolled. Overall, high PD-L1 expression was not significantly associated with OS, PFS, RFS, CSS and DFS of gynecological cancers. However, subgroup analysis of studies with reported HR (HR = 1.27) and a cut-off value of 5% (HR = 2.10) suggested that high PD-L1 expression was correlated with a shorter OS of gynecological cancer patients. Further sub-subgroup analysis revealed that high PD-L1 expressed on tumor-infiltrating immune cells (TICs) predicted a favorable OS for ovarian (HR = 0.72), but a poor OS for cervical cancer (HR = 3.44). PD-L1 overexpression was also correlated with a lower OS rate in non-Asian endometrial cancer (HR = 1.60). High level of PD-L1 was only clinically correlated with a shorter PFS in Asian endometrial cancer (HR = 1.59). Furthermore, PD-L1-positivity was correlated with LNM (for overall, ovarian and endometrial cancer expressed on tumor cells), advanced FIGO stage (for overall, ovarian cancer expressed on tumor cells, endometrial cancer expressed on tumor cells and TICs), LVSI (for overall and endometrial cancer expressed on tumor cells and TICs), and increasing infiltration depth/high grade (only for endometrial cancer expressed on TICs). Patients with PD-L1-positivity may obtain more benefit from anti-PD-1/PD-L1 treatment than the negative group, showing a higher ORR (RR = 1.98), longer OS (HR = 0.34) and PFS (HR = 0.61).

Conclusion

Our findings suggest high PD-L1 expression may be a suitable biomarker for predicting the clinical outcomes in patients with gynecological cancers.