Provectus Biopharmaceuticals, Inc., a development-stage oncology and dermatology biopharmaceutical company, has announced that a poster presentation detailing significant decrease in melanoma cells in patients' injected tumors 7-14 days after intralesional PV-10 treatment that was accompanied by similar decrease in uninjected bystander tumors was presented April 6 by researchers from the Moffitt Cancer Center at the American Association for Cancer Research Annual Meeting in San Diego, CA. These clinical and pathologic changes were accompanied by increases in important immune cell populations detected in the patients' peripheral blood.
The poster presentation, based upon abstract #630, entitled "Induction of anti-melanoma immunity after intralesional ablative therapy," was authored by Hao Liu, Krithika Kodumudi, Amy Weber, Amod A. Sarnaik and Shari Pilon-Thomas of the Moffitt Cancer Center.
Provectus' investigational drug PV-10, a 10% solution of Rose Bengal, is currently being studied as a novel cancer therapeutic, and Provectus has applied to the FDA for breakthrough therapy designation of PV-10 for the treatment of melanoma based on a 7 center international single-arm trial. PV-10 is designed to selectively target and destroy cancer cells without harming surrounding healthy tissue, significantly reducing potential for systemic side effects. In melanoma patients, intralesional (IL) injection of PV-10 has led to regression of injected lesions as well as uninjected metastases. The mechanism of regression of uninjected lesions is under investigation at Moffitt Cancer Center (NCT01760499). Further information can be accessed at the following NIH Registry link: http://www.clinicaltrials.gov/ct2/show/NCT01760499?term=provectus&rank=10
The Moffitt researchers presented clinical data on 8 melanoma patients that demonstrated significant decreases in melanoma cells in injected tumors and uninjected bystander tumors 7-14 days after PV-10 injection as evidenced by pathologic evaluation confirmed with immunohistochemical staining of biopsy specimens for melA (a marker of melanoma). The researchers showed that these changes in tumors were accompanied by increased populations of CD3+, CD4+ and CD8+ T cells along with NKT cells in peripheral blood. T cells from one patient were purified and exhibited increased interferon-gamma expression when exposed to the patient's pre-treatment melanoma cells.
In addition, Moffitt's team found that PV-10 was cytotoxic to B16 mouse melanoma cells with minimal cytotoxicity to normal skin cells (fibroblasts). This cytotoxicity occurred via necrosis with minimal evidence of apoptosis. The PV-10 treatment of B16 tumors in mice led to release of HMGB1, a soluble Damage Associated Molecule Pattern (DAMP) that is important in activation of dendritic cells; such dendritic cells from these mice were selectively active against B16 tumor cells. PV-10 treatment of B16 tumors in mice also led to infiltration of dendritic cells into the lymph nodes draining the treated tumors; no infiltration was observed in non-draining nodes.
Dr. Pilon-Thomas of Moffitt stated, "These data are exciting and illustrate successful translation of our pre-clinical work in mice to clinical results in melanoma patients. With only 8 patients we've been able to clearly observe statistically significant increases in beneficial T cell populations in peripheral blood. Ironically, the original aim of the trial to assess tumor-infiltrating lymphocytes was thwarted when biopsies of patient tumors collected just 7-14 days after PV-10 injection no longer contained viable tumor tissue. We are following up both the human data and continuing to design more experiments in mice to better explain the systemic immune effects elicited by PV-10 ablation."
Dr. Craig Dees, PhD, CEO of Provectus said, "Provectus is thrilled to collaborate with the immunology and translational medicine experts Moffitt. As more data become available on the 'bystander effect' we've consistently observed in our therapeutic trials, we can better position PV-10 to help the most patients. We are grateful to the team conducting the work upon which the poster was based, and believe that their findings further establish the potential PV-10 has as a powerful tool in the physician's toolbox to fight cancer."
Abstract #630 can be accessed here.