Abstract CT150: Initial analysis of open-label administration of autologous tumor lysate (TL) + dendritic cells (DC) vaccine (TLPLDC) in melanoma patients who recurred during a phase IIb adjuvant vaccine trial

INTRODUCTION: Patients(pts) with stage III-IV melanoma have a high risk of recurrence after resection despite standard of care therapies (SOC). Melanoma has proven to be immunogenic, and many novel treatment strategies targeting this have been initiated. We are conducting a phase IIb double-blind randomized trial of a vaccine consisting of autologous TL loaded into DC via yeast cell will particles (YCWP) to prevent recurrence (primary endpoint) after resection. Patients who recurred were offered open-label TLPLDC vaccination. Here we report a description of outcomes of pts who recurred and continued on open label TLPLDC vaccination. METHODS: Pts with resected stage III/IV melanoma were randomized to TLPLDC vs empty YCWP loaded DC in a 2:1 fashion. TLPLDC is created by in vitro loading of DC by YCWPs derived from S.cerevisiae containing autologous TL, then given as 1-1.5x106 TLPLDC inoculations. Patients who recurred on the trial (primary endpoint) were offered open label TLPLDC vaccination along with SOC therapy as determined by the pts treatment team. Disease status is measured by RECIST criteria on imaging as ordered by the primary physician. RESULTS: To date, 16 pts have received active open-label vaccine after recurrence with a median of 5.3 months follow-up since initiating open-label vaccine therapy. 8 pts had no evidence of disease (NED) after surgery ± XRT. Of these 8 pts treated with surgery ± XRT, 2 had an additional recurrence. The remaining 8 pts received systemic SOC therapy + adjuvant TLPLDC for recurrent, unresectable metastatic disease since their initial recurrence. Of these 8 pts, 3 were treated with pembrolizumab, 1 BRAF/MEK inhibition, and 1 TVEC. 2 pts treated systemically currently have NED, 2 have stable disease, and 3 have disease progression. CONCLUSION: On initial analysis, open label administration of the TLPLDC vaccine after recurrence may have benefit when combined with SOC therapy in the adjuvant setting and in patients with measurable metastatic disease. Additional follow up and controlled trials are needed to confirm benefit in this setting. Citation Format: Tommy A. Brown, John W. Myers, Tim J. Vreeland, Diane F. Hale, Kaitlin M. Peace, Doreen O. Jackson, Julia M. Greene, Julia M. Greene, John S. Berry, Garth Herbert, Xianzhong Yu, Thomas Wagner, Guy Travis Clifton, George Peoples. Initial analysis of open-label administration of autologous tumor lysate (TL) + dendritic cells (DC) vaccine (TLPLDC) in melanoma patients who recurred during a phase IIb adjuvant vaccine trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT150.