Renée C.G. de Bruin

Bispecific antibody platforms for cancer immunotherapy

Over the past decades advances in bioengineering and expanded insight in tumor immunology have resulted in the emergence of novel bispecific antibody (bsAb) constructs that are capable of redirecting immune effector cells to the tumor microenvironment. (Pre-) clinical studies of various bsAb constructs have shown impressive results in terms of immune effector cell retargeting, target dependent activation and the induction of anti-tumor responses. This review summarizes recent advances in the field of bsAb-therapy and limitations that were encountered. Furthermore, we will discuss potential future developments that can be expected to take the bsAb approach successfully forward.

Circulating Invariant Natural Killer T-Cell Numbers Predict Outcome in Head and Neck Squamous Cell Carcinoma: Updated Analysis With 10-Year Follow-Up

Circulating invariant natural killer T-cell numbers predict outcome in head and neck squamous cell carcinoma: Updated analysis with 10-year follow-up

Activated iNKT cells promote Vγ9Vδ2-T cell anti-tumor effector functions through the production of TNF-α

Vγ9Vδ2-T cells constitute a proinflammatory lymphocyte subpopulation with established antitumor activity. Phosphoantigens activate Vγ9Vδ2-T cells in vivo and in vitro. We studied whether the antitumor activity of Vγ9Vδ2-T cells can be potentiated by invariant NKT cells (iNKT), an important immunoregulatory T cell subset. When activated by the glycolipid α-galactosylceramide (α-GalCer), iNKT produce large amounts of cytokines involved in antitumor immune responses. Monocyte-derived dendritic cells were loaded with both phosphoantigens (using aminobisphosphonates) and α-GalCer during maturation and subsequently co-cultured with Vγ9Vδ2-T and iNKT cells. Aminobisphosphonates dose-dependently enhanced Vγ9Vδ2-T cell activation, and this was potentiated by α-GalCer-induced iNKT co-activation. iNKT co-activation also enhanced the IFN-γ production and cytolytic potential of Vγ9Vδ2-T cells against tumor cells. Using transwell experiments and neutralizing antibodies cross-talk between iNKT and Vγ9Vδ2-T cells was found to be mediated by TNF-α. Our data provide a rationale for combining both activating ligands to improve Vγ9Vδ2-T cell based approaches in cancer-immunotherapy.

Highly specific and potently activating Vγ9Vδ2-T cell specific nanobodies for diagnostic and therapeutic applications

Vγ9Vδ2-T cells constitute the predominant subset of γδ-T cells in human peripheral blood and have been shown to play an important role in antimicrobial and antitumor immune responses. Several efforts have been initiated to exploit these cells for cancer immunotherapy, e.g. by using phosphoantigens, adoptive cell transfer, and by a bispecific monoclonal antibody based approach. Here, we report the generation of a novel set of Vγ9Vδ2-T cell specific VHH (or nanobody). VHH have several advantages compared to conventional antibodies related to their small size, stability, ease of generating multispecific molecules and low immunogenicity. With high specificity and affinity, the anti-Vγ9Vδ2-T cell receptor VHHs are shown to be useful for FACS, MACS and immunocytochemistry. In addition, some VHH were found to specifically activate Vγ9Vδ2-T cells. Besides being of possible immunotherapeutic value, these single domain antibodies will be of great value in the further study of this important immune effector cell subset.

Prevention of Vγ9Vδ2 T Cell Activation by a Vγ9Vδ2 TCR Nanobody

Vγ9Vδ2 T cell activation plays an important role in antitumor and antimicrobial immune responses. However, there are conditions in which Vγ9Vδ2 T cell activation can be considered inappropriate for the host. Patients treated with aminobisphosphonates for hypercalcemia or metastatic bone disease often present with a debilitating acute phase response as a result of Vγ9Vδ2 T cell activation. To date, no agents are available that can clinically inhibit Vγ9Vδ2 T cell activation. In this study, we describe the identification of a single domain Ab fragment directed to the TCR of Vγ9Vδ2 T cells with neutralizing properties. This variable domain of an H chain–only Ab (VHH or nanobody) significantly inhibited both phosphoantigen-dependent and -independent activation of Vγ9Vδ2 T cells and, importantly, strongly reduced the production of inflammatory cytokines upon stimulation with aminobisphosphonate-treated cells. Additionally, in silico modeling suggests that the neutralizing VHH binds the same residues on the Vγ9Vδ2 TCR as the Vγ9Vδ2 T cell Ag-presenting transmembrane protein butyrophilin 3A1, providing information on critical residues involved in this interaction. The neutralizing Vγ9Vδ2 TCR VHH identified in this study might provide a novel approach to inhibit the unintentional Vγ9Vδ2 T cell activation as a consequence of aminobisphosphonate administration.

A bispecific nanobody approach to leverage the potent and widely applicable tumor cytolytic capacity of Vγ9Vδ2-T cells

ABSTRACT Though Vγ9Vδ2-T cells constitute only a small fraction of the total T cell population in human peripheral blood, they play a vital role in tumor defense and are therefore of major interest to explore for cancer immunotherapy. Vγ9Vδ2-T cell-based cancer immunotherapeutic approaches developed so far have been generally well tolerated and were able to induce significant clinical responses. However, overall results were inconsistent, possibly due to the fact that these strategies induced systemic activation of Vγ9Vδ2-T cells without preferential accumulation and targeted activation in the tumor. Here we show that a novel bispecific nanobody-based construct targeting both Vγ9Vδ2-T cells and EGFR induced potent Vγ9Vδ2-T cell activation and subsequent tumor cell lysis both in vitro and in an in vivo mouse xenograft model. Tumor cell lysis was independent of KRAS and BRAF tumor mutation status and common Vγ9Vδ2-T cell receptor sequence variations. In combination with the conserved monomorphic nature of the Vγ9Vδ2-TCR and the facile replacement of the tumor-specific nanobody, this immunotherapeutic approach can be applied to a large group of cancer patients.

Generation and characterization of CD1d-specific single-domain antibodies with distinct functional features.

Ligation of the CD1d antigen‐presenting molecule by monoclonal antibodies (mAbs) can trigger important biological functions. For therapeutic purposes camelid‐derived variable domain of heavy‐chain‐only antibodies (VHH) have multiple advantages over mAbs because they are small, stable and have low immunogenicity. Here, we generated 21 human CD1d‐specific VHH by immunizing Lama glama and subsequent phage display. Two clones induced maturation of dendritic cells, one clone induced early apoptosis in CD1d‐expressing B lymphoblasts and multiple myeloma cells, and another clone blocked recognition of glycolipid‐loaded CD1d by CD1d‐restricted invariant natural killer T (iNKT) cells. In contrast to reported CD1d‐specific mAbs, these CD1d‐specific VHH have the unique characteristic that they induce specific and well‐defined biological effects. This feature, combined with the above‐indicated general advantages of VHH, make the CD1d‐specific VHH generated here unique and useful tools to exploit both CD1d ligation as well as disruption of CD1d–iNKT interactions in the treatment of cancer or inflammatory disorders.

Improving CLL Vγ9Vδ2-T cell fitness for cellular therapy by ex vivo activation and ibrutinib

The efficacy of autologous (αβ) T-cell-based treatment strategies in chronic lymphocytic leukemia (CLL) has been modest. The Vγ9Vδ2-T cell subset consists of cytotoxic T lymphocytes with potent antilymphoma activity via a major histocompatibility complex-independent mechanism. We studied whether Vγ9Vδ2-T cells can be exploited as autologous effector lymphocytes in CLL. Healthy control Vγ9Vδ2-T cells were activated by and had potent cytolytic activity against CLL cells. However, CLL-derived Vγ9Vδ2-T cells proved dysfunctional with respect to effector cytokine production and degranulation, despite an increased frequency of the effector-type subset. Consequently, cytotoxicity against malignant B cells was hampered. A comparable dysfunctional phenotype was observed in healthy Vγ9Vδ2-T cells after coculture with CLL cells, indicating a leukemia-induced mechanism. Gene-expression profiling implicated alterations in synapse formation as a conceivable contributor to compromised Vγ9Vδ2-T-cell function in CLL patients. Dysfunction of Vγ9Vδ2-T cells was fully reversible upon activation with autologous monocyte-derived dendritic cells (moDCs). moDC activation resulted in efficient expansion and predominantly yielded Vγ9Vδ2-T cells with a memory phenotype. Furthermore, ibrutinib treatment promoted an antitumor T helper 1 (TH1) phenotype in Vγ9Vδ2-T cells, and we demonstrated binding of ibrutinib to IL-2-inducible kinase (ITK) in Vγ9Vδ2-T cells. Taken together, CLL-mediated dysfunction of autologous Vγ9Vδ2-T cells is fully reversible, resulting in potent cytotoxicity toward CLL cells. Our data support the potential use of Vγ9Vδ2-T cells as effector T cells in CLL immunotherapy and favor further exploration of combining Vγ9Vδ2-T-cell-based therapy with ibrutinib.

Correction: Prevention of Vγ9Vδ2 T Cell Activation by a Vγ9Vδ2 TCR Nanobody

de Bruin, R. C. G., A. G. M. Stam, A. Vangone, P. M. P. van Bergen en Henegouwen, H. M. W. Verheul, Z. Sebestyen, J. Kuball, A. M. J. J. Bonvin, T. D. de Gruijl, and H. J. van der Vliet. 2017. Prevention of Vγ9Vδ2 T cell activation by a Vγ9Vδ2 TCR nanobody. J. Immunol . 198: [308–317][1].

Specific tumor targeting and activation of Vγ9Vδ2 T cells by bi-specific nanobodies

Gamma delta T cells expressing the Vγ9Vδ2 T cell receptor (TCR) are the most predominant γδ-T cell subset in peripheral blood accounting for approximately 1-5 % of all T cells. Vγ9Vδ2 T cells recognize phosphoantigens (pAg) such as isopentenyl pyrophosphate (IPP), a naturally occurring pAg that can accumulate in tumor cells, resulting in activation, cytokine release and anti-tumor activity of Vγ9Vδ2 T. The use of Vγ9Vδ2 T cells in clinical trials, either via adoptive transfer of ex vivo expanded Vγ9Vδ2 T cells or through in vivo activation by aminobisphosphonates or synthetic pAg, has led to promising results. Anti-tumor responses were observed in some patients, but overall results lack consistency. This might be related to systemic activation of Vγ9Vδ2 T cells in these trials, not providing a specific trigger for these cells to accumulate at the tumor site. In order to improve the efficacy of Vγ9Vδ2 T cell based immunotherapy, we focused on the design of a tumor-targeting construct that binds both the TCR of Vγ9Vδ2 T cells and the Epidermal Growth Factor Receptor (EGFR), which is over-expressed by many tumor types, including Vγ9Vδ2 T cell susceptible tumors like colon carcinoma and head and neck cancer. For this bi-specific construct an antagonistic anti-EGFR single domain antibody fragment (VHH or Nanobody) and an agonistic anti-Vγ9Vδ2 TCR VHH were identified, characterized and constructed into a bi-specific targeting molecule. Only when bound to both EGFR expressing tumor cells and Vγ9Vδ2 T cells, this bi-specific targeting molecule induced Vγ9Vδ2 T cell activation, release of IFN-γ and TNF-α as well as up-regulated expression of cytolytic molecules such as perforin-and granzyme B. Importantly, tumor targeted Vγ9Vδ2 T cells were able to efficiently lyse EGFR expressing tumor cells in vitro. This study shows that bi-specific anti-Vγ9Vδ-T-anti-EGFR-nanobodies can specifically and efficiently lyse EGFR-expressing tumor cells and are promising candidates for cancer immunotherapy.