ILLUMINATE 301: A randomized phase 3 study of tilsotolimod in combination with ipilimumab compared with ipilimumab alone in patients with advanced melanoma following progression on or after anti-PD-1 therapy

TPS9599 Background: Tilsotolimod (IMO-2125) is a Toll-like receptor (TLR) 9 agonist with potent immunostimulating activity. In an ongoing Phase 1/2 clinical study in patients with advanced melanoma who progressed on or after anti-PD-1 therapy (NCT02644967), intratumoral (IT) tilsotolimod with ipilimumab was well-tolerated, demonstrating durable responses (including complete response > 21 months), dendritic cell activation, type I interferon response, CD8+ T-cell proliferation in responders, and an abscopal effect. Methods: ILLUMINATE 301 (NCT03445533) is a randomized phase 3 global, multi-center, open-label study of IT tilsotolimod (8 mg) in combination with ipilimumab (3 mg/kg) versus ipilimumab monotherapy in patients with advanced melanoma and progression on or after anti-PD-1 therapy. Eligible patients are ≥18 years with histologically confirmed unresectable Stage III or Stage IV melanoma, ≥1 measurable lesion accessible for injection (superficial or visceral, the latter with image guidance), ECOG PS ≤1, and adequate organ function. Exclusion criteria include prior TLR agonists, prior ipilimumab (except adjuvant ≥12 weeks before progression), and CNS disease other than stable brain metastases. Patients are randomized 1:1 and stratified by duration of prior anti-PD-1 (≥12 weeks vs