119 ADI-002: an IL-15 armored allogeneic ‘off-the-shelf’ Vδ1 gamma delta CAR T cell therapy for solid tumors targeting glypican-3 (GPC3)

Abstract

BackgroundGlypican-3 (GPC-3) is an oncofetal protein that is highly expressed in various solid tumors including hepatocellular carcinoma (HCC) but is rarely expressed in healthy adult tissues and serves as a therapeutic target of interest. Autologous αβ chimeric antigen receptor (CAR) T cell therapy has established clinical benefit in hematologic malignancies but limited success in solid tumors due to numerous challenges including poor T cell homing, heterogenous antigen expression, and hostile tumor microenvironments.1 These challenges may be overcome by the Vδ1 subset of gamma delta T cells due to their natural peripheral tissue tropism and ability to recognize and kill tumor cells through MHC-independent antigens upregulated under stress.2 Allogeneic Vδ1 T cells engineered with CARs can have enhanced intrinsic antitumor activity and overcome challenges of allogeneic αβ T cells, including graft-versus-host disease (GvHD). Here, we describe the first preclinical evaluation of ADI-002, a next-generation allogeneic CAR Vδ1 T cell therapy targeting GPC-3 and armored with IL-15, for the treatment of solid tumors.MethodsVδ1 T cells were expanded from healthy donor PBMCs and transduced to express a 4–1BB/CD3z CAR against GPC-3 that encodes constitutively-secreted IL-15 (sIL-15), which we hypothesized could sustain proliferation and antitumor activity of intratumoral GPC-3.CAR Vδ1 T cells. In vitro characterization included co-culture with HCC targets expressing high (HepG2) and low (PLC/PRF/5) GPC-3, phenotypic analysis by flow cytometry, and cytokine production by multiplexed immunoassay. For in vivo assessment, immunodeficient NSG mice were subcutaneously injected with HepG2 tumor cells and treated with a single dose of GPC-3.CAR Vδ1 T cells. Tissues were harvested 7 days post transfer and analyzed for Vδ1 T cell tissue homing and proliferation, or at study end and analyzed for GvHD by immunohistochemistry.ResultsGPC-3.sIL-15.CAR Vδ1 T cells expanded over 10,000-fold and routinely reached >80% purity. Expanded Vδ1 T cells showed a primarily naïve-like phenotype (CD45RA+CD27+) with minimal exhaustion receptor expression and displayed robust proliferation, cytokine production, and cytotoxic activity against HCC cell lines in vitro. In vivo, GPC-3.sIL-15.CAR Vδ1 T cells primarily accumulated and proliferated in tumors, and a single dose could efficiently control tumor burden without causing GvHD. When compared to GPC-3.CAR Vδ1 T cells lacking sIL-15, GPC-3.sIL-15.CAR Vδ1 T cells displayed greater tumor-specific proliferation that resulted in enhanced tumor control (figure 1).Abstract 119 Figure 1In vivo antitumor efficacy in a subcutaneous HepG2 tumor model in NSG miceConclusionsExpanded Vδ1 T cells engineered with GPC-3.CAR and sIL-15 represent a promising approach for safe and effective off-the-shelf treatment of HCC and support further investigation in the clinical setting.ReferencesLabanieh L, Majzner RG, Mackall CL. Programming CAR-T cells to kill cancer. Nat Biomed Eng 2018;2(6):377–91.Sebestyen Z, Prinz I, Déchanet-Merville J, Silva-Santos B, Kuball J. Translating gammadelta (γδ) T cells and their receptors into cancer cell therapies. Nat Rev Drug Discov 2020;19(3):169–84.Ethics ApprovalAll mouse experiments were performed in accordance with the Guide for the Care and Use of Laboratory Animals and followed all institutional and national guidelines and after appropriate approvals.