Abstract CT105: Safety and feasibility of chimeric antigen receptor modified T cells directed against mesothelin (CART-meso) in patients with mesothelin expressing cancers

A phase I study to evaluate the safety and feasibility of an intravenous infusion of autologous T cells transduced to express a chimeric antigen receptor directed against mesothelin (CART-meso) in patients with mesothelin expressing tumors is being conducted at the University of Pennsylvania. Here we report on the first five patients treated with CART-meso T cell infusion. Five patients with recurrent advanced stage cancers (two serous ovarian, two epithelial mesothelioma, and one pancreatic) who had received 4-12 prior regimens, were treated with a single infusion of CART-meso cells. Apheresed autologous T cells were transduced with a lentiviral vector expressing the CAR construct composed of an extracellular anti-mesothelin single chain variable fragment derived from mouse monoclonal antibody (SS1) fused to the intracellular signaling domains of 4-1BB (CD137) and TCRzeta. Each patient received a single dose of 1-3 × 10^7 CART-meso cells/m2. No lymphodepletion with chemotherapy was given prior to infusion. All subjects enrolled were successfully infused and there were no acute adverse events (AE) with infusion. To date, Grade 4 AEs have included sepsis(1), anemia(1), pleural effusions(1), tachypnea(1), dyspnea(1), and aspiration(1) and Grade 3 AEs have included sepsis(1), leukocytosis(2), DIC(1), tachycardia(1), dyspnea(1), hypotension(1), dusky extremities(1), fatigue(1), ascites(1), peritonitis(1), elevated LFTs(1), portal vein hypertension(1), and acute kidney injury(1). After infusion, CART-meso T cells were transiently detectable by PCR in the peripheral blood in all patients up to Day 21-28 after infusion. CART-meso cells were found to traffic to tumor sites within the peritoneum and liver, as well as to off-tumor on-target sites such as pericardial fluid, but without clinical toxicity of pericarditis. Expansion of CART-meso cells was also observed in the pleural fluid of one patient who had a known malignant pleural effusion. Cytokine profiling of the peripheral blood revealed elevations of IL-6 and VEGF with significant elevations seen in the one patient with malignant pleural effusion. No elevations in TNFα or IFNγ were found. Anti-tumor efficacy is suggested by the clearing of malignant cells in the pleural fluid of one patient on Day 21 and Day 26 after infusion, as well as radiological and clinical evidence of stable to decreased burden of disease in one patient. Patient follow-up for 1-3 months post infusion has revealed no evidence of long-term toxicities to date. These interim results suggest that intravenous infusion of CART-meso T cells without lymphodepletion is feasible and safe. In these five patients with metastatic mesothelin expressing cancers, the infusion was well tolerated with no off-tumor on-target toxicities. Laboratory and clinical findings suggest infused T cells are effective and functional. Citation Format: Janos L. Tanyi, Andrew R. Haas, Gregory L. Beatty, Mark A. Morgan, Caitlin J. Stashwick, Mark H. O9Hara, David L. Porter, Marcela V. Maus, Bruce L. Levine, Simon F. Lacey, Anne Marie Nelson, Maureen McGarvey, Naseem DS Kerr, Gabriela Plesa, Carl H. June. Safety and feasibility of chimeric antigen receptor modified T cells directed against mesothelin (CART-meso) in patients with mesothelin expressing cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT105. doi:10.1158/1538-7445.AM2015-CT105