US-based OncoSec Medical has reported positive top-line six-month results from the first Phase II trial of its investigational intratumoral plasmid IL-12 electroporation (pIL-12 EP) monotherapy (ImmunoPulse IL-12) in patients with Stage III and IV metastatic melanoma.
In the trial, 30 patients with stage III-IV melanoma received about four cycles of pIL-12 EP into superficial cutaneous, subcutaneous and nodal lesions on days one, five and eight of each 12-week cycle.
The company said that tumour responses were evaluated using modified response evaluation criteria in solid tumours (RECIST) criteria for cutaneous lesions.
Primary endpoint of the trial was best overall response rate (bORR) by modified RECIST, while in the 29 response-evaluable patients bORR was 31%, with 14% of patients achieving a complete response (CR).
The company said that regression of at least one non-injected, non-electroporated lesion was observed in 50% of patients.
The data from this trial was presented by OncoSec chief scientific officer Dr Robert Pierce in an abstract at the Melanoma Bridge 2014 conference in Naples, Italy.
OncoSec chief medical officer Dr Mai Le said: "Along with the Phase I long-term survival analysis presented yesterday, these data continue to support the use of pIL-12 EP as a treatment for metastatic melanoma.
"Importantly, our observation that non-treated lesions regress in approximately half of the patients suggests that local, intratumoral pIL-12 EP successfully induces a more global anti-tumour immune-mediated response."
In the trial, the most common treatment-related adverse event (AE) observed was transient Grade 1/2 pain at the treatment site, reported in 87% of patients.
Dr Pierce said: "We are pleased to see such good concordance between our findings from patient biopsy samples and the B16.F10 mouse model.
"This gives us confidence that we can use this experimental model to deepen our understanding of how ImmunoPulse re-programs the immune system to drive a systemic anti-cancer immune response."