Anti-mesothelin CAR-T cell therapy(University of Pennsylvania)

This phase I study investigated the safety and activity of lentiviral-transduced chimeric antigen receptor (CAR)-modified autologous T cells redirected against mesothelin (CART-meso) in patients with malignant pleural mesothelioma, ovarian carcinoma, and pancreatic ductal adenocarcinoma. Fifteen patients with chemotherapy-refractory cancer (n = 5 per indication) were treated with a single CART-meso cell infusion. CART-meso cells were engineered by lentiviral transduction with a construct composed of the anti-mesothelin single-chain variable fragment derived from the mouse monoclonal antibody SS1 fused to intracellular signaling domains of 4-1BB and CD3zeta. Patients received 1-3 × 10⁷ or 1-3 × 10⁸ CART-meso cells/m² with or without 1.5 g/m² cyclophosphamide. Lentiviral-transduced CART-meso cells were well tolerated; one dose-limiting toxicity (grade 4, sepsis) occurred at 1-3 × 10⁷/m² CART-meso without cyclophosphamide. The best overall response was stable disease (11/15 patients). CART-meso cells expanded in the blood and reached peak levels by days 6-14 but persisted transiently. Cyclophosphamide pre-treatment enhanced CART-meso expansion but did not improve persistence beyond 28 days. CART-meso DNA was detected in 7/10 tumor biopsies. Human anti-chimeric antibodies (HACA) were detected in the blood of 8/14 patients. CART-meso cells were well tolerated and expanded in the blood of all patients but showed limited clinical activity. Studies evaluating a fully human anti-mesothelin CAR are ongoing.

Cytokine release syndrome (CRS) is a potentially severe systemic toxicity seen after adoptive T-cell therapy and caused by T-cell activation and proliferation and is associated with elevated circulating levels of cytokines such as C-reactive protein, interleukin-6 (IL-6), and interferon-γ and has previously been described as a systemic response in hematologic malignancies. A 52-year-old woman with BRCA 1 mutation positive heavily pretreated advanced recurrent serous ovarian cancer was treated under a compassionate use protocol with autologous mesothelin-redirected chimeric antigen receptor T cells (CART-meso). Autologous T cells were transduced to express a receptor composed of an extracellular antimesothelin single-chain variable fragment fused to 4-1BB and TCR-zeta signaling domain. This patient was infused with 3×107 CART-meso T cells/m2 without lymphodepletion and developed compartmental CRS confined to the pleural cavities. The compartmental CRS was evidenced by an increase in IL-6 and accumulation of CART-meso T cells in pleural fluid compared with peripheral blood and was successfully treated the anti-IL6 receptor antagonist tocilizumab on D21 after the T-cell infusion. This is the first description of a compartmental CRS in a patient with solid malignancy. This response could be due to malignant pleural fluid creating an environment where T cells could interact with tumor cells and suggests localized on-target CAR-T-cell activation.