PV-10 delivers greatest effects when all lesions are injected

The rationale for PV-10, a 10% solution of Rose Bengal developed first as a dye, is that the agent has a local chemo ablative effect where it enters lysosomes causing local necrosis, and then in some patients a systemic effect believed to be immunologically mediated. Previous studies have demonstrated increased CD8+, CD4+, CD3+ and NKT in peripheral blood within seven days of injection.

In the open label phase 2 study 80 patients with stage IIIB-IV melanoma, refractory to a median of six prior interventions, received intralesional injections for cutaenous and subcutaneous melanoma lesions (up to 20) with PV-10 up to four times over a 16-week period and were followed for 52 weeks.

Results reported earlier showed the overall response rate for the 28 patients who had all their existing melanoma lesions injected with PV-10, was 71% (CI 51-87%) with 50% achieving a complete response (CI 31-69%). Furthermore, when the 28 patients who had all their lesions injected were analysed together with 26 patients who had one or two lesions left untreated (to investigate bystander effects) a complete response was achieved in 64% (232 out of the 363 injected lesions).

The latest analysis reported at ESMO reveals that the subgroup of 28 patients who had all their lesions injected achieved a progression free survival of 9.8 months compared to 6.0 months for the seven patients who had a median of five untreated lesions. “The progression free survival of 9.8 months compares favourably with historical progression free survivals of less than 2.5 months for DTIC/TMZ,” commented Sanjiv Agarwala, the first author from St. Luke’s Hospital and Health Network, Bethlehem, Pennsylvania.

Such data he added, suggests PV-10 will deliver significant progression free survival effects in the phase 3 study, due to start Q4 2014. “The abstract also shows us that we’re likely to get the highest responses when all the lesions are injected,” said Agarwala.

The analysis furthermore found that 121 lesions required a single injection for complete response, 84 required two injections, 22 required three injections and five required four injections. “The few injections needed in this study bode well for patient compliance with PV-10-treatment,” said Eric Wachter, Chief Technology Officer of Provectus, who developed PV-10.

Reference

1.      S Agarwala, J Thompson, B Smithers, et al. Subgroup Efficacy in Patients receiving intralesional Rose Bengal to all existing melanoma in Phase II study PV-10-MM-02. Abstract no 1120P ESMO 2014.