Neoadjuvant Intratumoral Plasmid IL-12 Electro-Gene-Transfer and Nivolumab in Patients with Operable, Locoregionally Advanced Melanoma

Purpose: Intratumoral tavokinogene telseplasmid delivered by electroporation (TAVO-EP) results in localized expression of IL-12 within the tumor microenvironment (TME). This study evaluated neoadjuvant TAVO-EP combined with intravenous nivolumab followed by surgery and adjuvant nivolumab in patients with operable, locoregionally advanced melanoma.Patients and Methods: The neoadjuvant phase comprised up to 3 x 4-week cycles during which TAVO-EP was given intratumorally on days 1, 8, and 15 (optional) concurrently with 480 mg nivolumab intravenously on day 8 of each 4-week cycle. Surgery followed, and adjuvant nivolumab was initiated after surgery. The primary endpoint was pathologic complete response (pCR). Secondary endpoints included major pathologic response (MPR; pCR or near pCR).Results: Sixteen patients were enrolled, and the preoperative radiological response rate was 63%. One patient declined surgery after experiencing a significant clinical response. Among the remaining 15 patients, the pCR rate was 60% and the MPR was 80%. No patient with MPR has had disease recurrence with a median follow-up from the date of surgery of 15.4 months. At baseline, most patients exhibited low CD8+ tumor-infiltrating lymphocytes, PD-L1, and IFN-gamma gene expression signature. There was enhanced immune activation following treatment in the TME and blood, including increased immune-related gene expression, CD8+ tumor-infiltrating lymphocytes, and proliferating immune cell subsets.Conclusions: The clinical efficacy of neoadjuvant intratumoral TAVO-EP + nivolumab is promising with 80% of patients achieving an MPR. Evidence of potent immune activation both systemically and within the TME along with a favorable safety profile supports the activity of local IL-12 and anti-PD-1 based regimens.