Obsidian Therapeutics has raked in $115 million to realize the long-unfulfilled therapeutic promise of tumor-infiltrating lymphocytes (TILs). The series B gives Obsidian a shot at showing whether freeing TILs from IL-2 can finally unleash power that research has hinted at for almost 30 years.
Researchers at the NIH began revealing the therapeutic potential of TILs in patients with metastatic melanoma in the 1990s. Given with high-dose IL2, the TILs triggered responses in around 70% of the participants. However, TILs struggled in indications beyond melanoma over the following years and toxicities linked to IL-2, notably fluid leakage from small blood vessels, held the modality back.