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

Abstract

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 × 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-γ 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.

Figure 1.. Trial design

This figure demonstrates the study design, intervention time, and assessment times. SOC; standard of care, TAVO; tavokinogene telseplasmid, EP; electroporation; IV; intravenous; CT; computed tomography, MRI; magnetic resonance imaging, PET; positron emission tomography

Figure 2.. Survival probability

These single-arm Kaplan Meier curves describe several survival endpoints over two years, as shown in the curve, and one-year survival probability as presented by percentage and confidence interval. (A) Relapse-free survival. (B) Event-free survival. (C) Overall survival. Event-free survival: Starting from the date of treatment initiation in the study to the date of disease progression, recurrence, or death. Two patients had disease progression: #1 had disease progression but underwent surgery, and #11 had early evidence of distant disease progression (including liver metastases) and therefore did not have surgery. Abbreviations: CI, confidence interval; EFS, event-free survival; OS, overall survival; RFS, recurrence-free survival.

Figure 3.. Changes in tumor biomarkers at the baseline and following treatment with TAVO-EP and nivolumab

(A) Baseline predictive markers for tumor response in melanoma. In tumor, at baseline, 9/11 patients tested had <20% CD8+ TIL, 7/11 <10% PD-L1 TPS and 6/10 TIS of ≤ 0, predicting non-response to anti-PD-1 (B) TIL and TIS changes indicate treatment effects in the TME. In five patients with evaluable matched tissue at baseline and C2D1: 5/5 had increased peritumoral CD8+ T cells, 4/5 increased CD8+ TIL, 2/5 increased PD-L1, 4/5 increased TIS. (C) Intra-tumoral transcriptome profile after neoadjuvant TAVO-EP + nivolumab. Significant upregulation of genes involved in innate and adaptive immune responses (IFN-γ, APM, granzymes, CD8, PDL1, JAK1 and chemokines) upon treatment with TAVO^™-EP and nivolumab. Abbreviations: C2D1, Cycle 2, Day 1; IFN-γ, interferon- γ; JAK1, Janus kinase 1; mAB, monoclonal antibody; pCR, pathologic complete response; PD-L1, programmed death-ligand 1; MPR, pathological major response; pNR, pathological non-response; PR, partial radiologic response; TAVO-EP, tavokinogene telseplasmid-electroporation; TME, tumor microenvironment; TIL, tumor-infiltrating lymphocyte; TIS, tumor inflammation signature; TPS, tumor proportion score.

Figure 4.. Changes in blood-based biomarkers at baseline and on-treatment with TAVO-EP and nivolumab.

(A) Treatment-related changes in peripheral immune cellular subsets. PBMC analysis by flow cytometry, proliferating Ki-67+/PD 1+/CD8+ T cells and total PD1+/CD8+ cells. Proliferating Ki-67+/PD-1+/CD8+ T cells expanded at C2D1 while total PD1+/CD8+ cells decreased. The decrease of PD1+CD8+ cells and other subtypes in blood at C2D1 coincided with TME infiltration by CD8+ cells. (B) Serum effector cytokine levels, including IL12, IFN-γ, and IL2, showed no biologically meaningful changes following treatment or differences between responders and non-responders. Abbreviations: C1D8, cycle 1, day 8; C2D1, cycle 2, day 2; C6D1, cycle 6, day 1; C12D1, cycle 11, day 1; EOS, end of study; interferon- γ, IFN-γ; IL-2, interlukin-2; IL-12, interlukin-12; PD-1, programmed death-1.