Researchers from Moffitt Cancer Center in Tampa, FL, presented a poster titled, “Intralesional Rose Bengal in Melanoma Elicits Tumor Immunity via High Mobility Group Box 1,” at the Society for Immunotherapy of Cancer (SITC) 30th Anniversary Annual Meeting in National Harbor, MD, according to Provectus Biopharmaceuticals, Inc..

Authors Hao Liu, Pasquale Patrick Inamarato, Krithika Kodumudi, Amy Weber, John L Robinson, Satoshi Nemoto, Georgina Crago, Timothy McCardle, Erica Royster, Amod A Sarnaik and Shari Pilon-Thomas state that their “results reveal a clinically relevant immunoadjuvant pathway triggered by tumor cell death secondary to ablation with RB.” The data presented were from nonclinical models of melanoma in mice and clinical data from the team’s recent clinical mechanism of action study (Clinical Trials ID NCT01760499). To view the poster, visit http://www.pvct.com/publications/SITC-Poster-2015.pdf.

In the reported work, the authors showed that tumor-specific T cells were increased in the blood of both mouse and man after tumor ablation with PV-10. This was initiated by tumor cell necrosis, leading to release of High Mobility Box Group 1 (HMBG1), one of a class Damage-Associated Molecular Pattern molecules (DAMPs) released by dying cancer cells that can lead to activation of dendritic cells. HMBG1 release was observed in vitro and after ablation of melanoma tumors in mice and clinical trial participants. This was also correlated with dendritic cell activation and infiltration into lymph nodes draining ablated tumors.

Eric Wachter, Ph.D., Chief Technology Officer of Provectus, observed, “The data reported by our collaborators at Moffitt further clarify the mechanism by which tumor ablation with PV-10 can initiate a finely tuned immune response against injected tumor cells. This has important potential implications for overall response and durability of response when PV-10 is used as a single agent therapy, while the central role played by T cells in this response is notable for combination of PV-10 with other agents that function on T cells.”

Provectus is currently enrolling patients in a Phase 3 study of PV-10 as a single agent therapy for patients with locally advanced cutaneous melanoma (Clinical Trials ID NCT02288897) and in a Phase 1b study of PV-10 in combination with the immune checkpoint inhibitor pembrolizumab in patients with metastatic melanoma (Clinical Trials ID NCT02557321).