Neoadjuvant intratumoral plasmid interleukin-12 electro-gene-transfer and nivolumab in patients with operable locoregionally advanced melanoma

Abstract Purpose: Intratumoral (IT) TAVO-EP (tavokinogene telseplasmid delivered by electroporation) results in localized expression of interleukin-12 (IL-12) within the tumor microenvironment (TME). This study evaluated neoadjuvant TAVO-EP combined with intravenous (IV) nivolumab followed by surgery and adjuvant nivolumab in patients with operable locoregionally advanced melanoma. Patients and Methods: The neoadjuvant phase comprised up to 3 Χ 4-week cycles where TAVO-EP was given IT on days 1, 8, and 15 (optional) concurrently with 480 mg nivolumab IV 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 pathological 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, pCR rate was 60% and 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+ TIL, PD-L1 and IFN-γ gene expression signature. There was enhanced immune activation following treatment in the TME and blood including increased immune-related gene expression, CD8+ TIL and proliferating immune cell subsets. Conclusions: The clinical efficacy of neoadjuvant IT 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-PD1 based regimens.