Abstract CT208: Prior vaccination with the autologous Tumor Lysate Particle Loaded Dendritic Cell (TLPLDC) Vaccine may impact clinical outcomes in melanoma patients treated with systemic therapies and re-vaccination

Abstract

Abstract Background: Melanoma is an immunogenic cancer, yet only 50-60% of tumors respond to current immunotherapy. The autologous tumor lysate, particle loaded, dendritic cell (TLPLDC) vaccine may potentiate an immune response by stimulating T-cells. We are conducting a phase IIb double-blinded randomized trial of TLPLDC to prevent recurrence after resection. Patients who recurred were offered enrollment in an open-label TLPLDC vaccine trial along with standard therapy. Here, we describe characteristics and clinical outcomes of recurred patients that continued on open label TLPLDC vaccination. Methods: Patients with resected no evidence of disease (NED) stage III/IV melanoma were randomized to TLPLDC vs. empty yeast cell wall particle (YCWP) loaded DC in a 2:1 fashion. TLPDC is created by loading autologous tumor lysate into YCWP. This is then introduced ex vivo to the patient’s DC for phagocytosis. 1-1.5x106TLPLDCs are given via intradermal injection monthly x4 followed by boosters at 6 and 9 months. Patients who recurred after receiving TLPLDC (vaccine group, VG) or after empty YCWP (control group, CG) on the trial (primary endpoint) were offered open label TLPLDC vaccination with same dosing schedule along with standard therapy as determined by the patient’s treatment team. Disease status is measured by RECIST criteria. Results: To date, 23 (14 VG and 11 CG) patients have enrolled and been vaccinated, with median follow up (fu) of 7.86 months (mo). The patients received the following additional therapies: surgery, gamma-knife, check point inhibitor, radiation, TVEC, BRAF/MEK, and imantinib. No related toxicities > grade 2 were observed. Of 14 VG patients, 5 were NED when re-enrolled, 9 had measurable disease (MD). Of these, 11 have followed up data, 9 (82%) show disease control (5/5 NED patients remain NED, 4/6 with MD show SD), while 2 (18%) have progressed. Of 9 CG patients, 4 were NED and 5 had measurable disease at time of re-enrollment. Of these, 8 have followed up, 5 (62%) show disease control (2/4 NED remain NED, 1/4 with MD shows regression, 2/4 SD), while 3 (38%) have progressed (2/4 NED, 1/3 with MD). Conclusion: Open label administration of TLPLPDC vaccine after recurrence is demonstrated as a safe therapy and shows potential clinical benefit when combined SOC therapy. Further study is warranted to determine if prior exposure to TLPLDC may provide clinical benefit after the first episode of disease recurrence. Citation Format: Annelies T. Hickerson, Guy T. Clifton, Tommy A. Brown, Jessica L. Cindass, John W. Myers, Timothy J. Vreeland, Diane F. Hale, Kaitlin M. Peace, Doreen O. Jackson, Garth Herbert, Xianzhong Yu, Thomas E. Wagner, George E. Peoples. Prior vaccination with the autologous Tumor Lysate Particle Loaded Dendritic Cell (TLPLDC) Vaccine may impact clinical outcomes in melanoma patients treated with systemic therapies and re-vaccination [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT208.