Obsidian is a private Cambridge, MA-based biotechnology company developing Tumor Infiltrating Lymphocyte (TIL) therapies for solid tumors, including melanoma and NSCLC. TILs are an established modality that utilizes t-cells harvested from a patient’s tumor that are expanded in the presence of proinflammatory cytokines, and then reintroduced back into the patient to elicit an anti-tumor immune response.