Chantale Bernatchez

CRISPR-mediated TGFBR2 knockout renders human ovarian cancer tumor-infiltrating lymphocytes resistant to TGF-β signaling

Background The correlation between elevated T-cell infiltration and improved survival of ovarian cancer (OvCa) patients suggests that endogenous tumor-infiltrating lymphocytes (TIL) possess some degree of antitumor activity that can be harnessed for OvCa immunotherapy. We previously optimized a protocol for ex vivo OvCa TIL expansion for adoptive cell therapy, which is now being tested in a clinical trial at our institution (NCT03610490). Building on this success, we embarked on genetic modification of OvCa TIL to overcome key immunosuppressive factors present in the tumor microenvironment. Here, we present the preclinical optimization of CRISPR/Cas9-mediated knockout of the TGF-β receptor 2 (TGFBR2) in patient-derived OvCa TIL. Methods OvCa TILs were generated from four patients’ tumor samples obtained at surgical resection and subjected to CRISPR/Cas9-mediated knockout of TGFBR2 before undergoing a rapid expansion protocol. TGFBR2-directed gRNAs were comprehensively evaluated for their TGFBR2 knockout efficiency and off-target activity. Furthermore, the impact of TGFBR2 knockout on TIL expansion, function, and downstream signaling was assayed. Results TGFBR2 knockout efficiencies ranging from 59±6% to 100%±0% were achieved using 5 gRNAs tested in four independent OvCa TIL samples. TGFBR2 knockout TIL were resistant to immunosuppressive TGF-β signaling as evidenced by a lack of SMAD phosphorylation, a lack of global transcriptional changes in response to TGF-β stimulation, equally strong secretion of proinflammatory cytokines in the presence and absence of TGF-β, and improved cytotoxicity in the presence of TGF-β. CRISPR-modification itself did not alter the ex vivo expansion efficiency, immunophenotype, nor the TCR clonal diversity of OvCa TIL. Importantly for clinical translation, comprehensive analysis of CRISPR off-target effects revealed no evidence of off-target activity for our top two TGFBR2-targeting gRNAs. Conclusions CRISPR/Cas9-mediated gene knockout is feasible and efficient in patient-derived OvCa TIL using clinically-scalable methods. We achieved efficient and specific TGFBR2 knockout, yielding an expanded OvCa TIL product that was resistant to the immunosuppressive effects of TGF-β. This study lays the groundwork for clinical translation of CRISPR-modified TIL, providing opportunities for engineering more potent TIL therapies not only for OvCa treatment, but for the treatment of other solid cancers as well.

Efficacy and safety of autologous tumor-infiltrating lymphocytes in recurrent or refractory ovarian cancer, colorectal cancer, and pancreatic ductal adenocarcinoma

Background Tumor-infiltrating lymphocyte (TIL) therapy has shown efficacy in metastatic melanoma, non-small cell lung cancer, and other solid tumors. Our preclinical work demonstrated more robust CD8 predominant TIL production when agonistic anti-4-1BB and CD3 antibodies were used in early ex vivo TIL culture. Methods Patients with treatment-refractory metastatic colorectal (CRC), pancreatic (PDAC) and ovarian (OVCA) cancers were eligible. Lymphodepleting chemotherapy was followed by infusion of ex vivo expanded TIL, manufactured at MD Anderson Cancer Center with IL-2 and agonistic stimulation of CD3 and 4-1BB (urelumab). Patients received up to six doses of high-dose IL-2 after TIL infusion. Primary endpoint was evaluation of objective response rate at 12 weeks using Response Evaluation Criteria in Solid Tumors version 1.1 with secondary endpoints including disease control rate (DCR), duration of response, progression-free survival (PFS), overall survival (OS), and safety. Results 17 patients underwent TIL harvest and 16 were treated on protocol (NCT03610490), including 8 CRC, 5 PDAC, and 3 OVCA patients. Median age was 57.5 (range 33–70) and 50% were females. Median number of lines of prior therapy was 2 (range 1–8). No responses were observed at 12 weeks. Ten subjects achieved at least one stable disease (SD) assessment for a DCR of 62.5% (95% CI 35.4% to 84.8%). Best response included prolonged SD in a patient with PDAC lasting 17 months. Median PFS and OS across cohorts were 2.53 months (95% CI 1.54 to 4.11) and 18.86 months (95% CI 4.86 to NR), respectively. Grade 3 or higher toxicities attributable to therapy were seen in 14 subjects (87.5%; 95% CI 61.7% to 98.4%). Infusion product analysis showed the presence of effector memory cells with high expression of CD39 irrespective of tumor type and low expression of checkpoint markers. Conclusions TIL manufactured with assistance of 4-1BB and CD3 agonism is feasible and treatment is associated with no new safety signals. While no responses were observed, a significant portion of patients achieved SD suggesting early/partial immunological effect. Further research is required to identify factors associated with resistance and functionally enhance T cells for a more effective therapy.

Autologous Tumor Infiltrating Lymphocytes MDA-TIL in Treating Patients With Recurrent or Refractory Ovarian Cancer, Colorectal Cancer, or Pancreatic Ductal Adenocarcinoma

This phase II trial studies how well autologous tumor infiltrating lymphocytes MDA-TIL works in treating patients with ovarian cancer, colorectal cancer, or pancreatic ductal adenocarcinoma that has come back (recurrent) or does not respond to treatment (refractory). Autologous tumor infiltrating lymphocytes MDA-TIL, made by collecting and growing specialized white blood cells (called T-cells) from a patient's tumor, may help to stimulate the immune system in different ways to stop tumor cells from growing.