BASECAMP-1: An Observational Study to Identify Relapsed Solid Tumor Patients With Human Leukocyte Antigen (HLA) Loss of Heterozygosity (LOH) and Leukapheresis for Future CAR T-Cell Therapy

SITC Annual Meeting 2021 Presentation
Authors Julian Molina, William Go, Scott Kopetz, Diane Simeone, Sandip Patel, Yi Lin, Kirstin Liechty, Michelle Fan-Port, Jason Perera, Armen Mardiros, Karl Beutner, Ariane Lozac’hmeur, Eric Ng, David Maloney, and J Randolph Hecht

Background Solid tumors comprise >90% of cancers. Metastatic colorectal cancer, non-small cell lung cancer, and pancreatic cancer are among the leading causes of cancer-related mortality (5-year overall survival: 14%, 6%, and 3%, respectively).1Chimeric antigen receptor (CAR) T-cell therapy demonstrated clinical outcomes in hematologic malignancies.2 3 However, translating engineered T-cell therapies to solid tumors proves difficult due to a lack of tumor-specific targets that discriminate cancer cells from normal cells. In previous studies, the use of a carcinoembryonic antigen T-cell receptors and mesothelin CARs both resulted in dose-limiting on-target, off-tumor toxicities.4 5 TmodTM CAR T-cell therapy addresses these challenges by leveraging dual receptors to create a robust AND NOT signal integrator capable of killing tumor cells, while leaving healthy cells intact (figure 1).6 Tmod platform technology is a versatile system that may be applied to T cells and natural killer cells in autologous and allogeneic settings. HLA LOH offers a definitive tumor versus normal discriminator target for CAR T-cell therapy.6 7 The 2 receptors comprise an activator that recognizes an antigen present on the surface of normal and tumor cells and a blocker that recognizes a second surface antigen from an allele lost only in tumor cells. HLA LOH has been observed in ~13% across all solid tumors and up to 33% of pancreatic cancers.8 New technologies have shown higher HLA LOH rates; however, it is unclear whether patients with HLA LOH in their primary tumor tissues are at higher risk for recurrence. BASECAMP-1 is an observational study with key objectives: 1) To determine and identify patients with somatic HLA LOH eligible for Tmod CAR T-cell therapy, and 2) Subsequent leukapheresis and manufacturing feasibility for future Tmod CAR T-cell trials.