e14025 Publication Only Personalized neoantigen-pulsed autologous dendritic cells vaccine as an adjuvant treatment for patients with newly-diagnosed glioblastoma multiforme: A phase I trial. Yang Zhang, Xiaohan Chi, Xudong Cheng, Yu Zhang, Kangna Zhang, Na Huang, Nan Ji; Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medic al University, Beijing, Beijing, China; Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China; ZSky BioTech Co. LTD, Beijing, China Background: Glioblastoma Multiforme (GBM) is the most common and aggressive primary brain malignancy in adults. We herein report a phase I trial using personalized neoantigen-pulsed autologous dendritic cells (nDC) vaccine as an adjuvant treatment for patients withnewly-diagnosed GBM. Methods: It is a single-center, single-arm phase I trial, enrolling patients aged 18-75 years old, with newly-diagnosed GBM and tumor resection extent $90%. Tumor specimens were sequenced for identification of personalized neoantigens. A total of 3-10 neoantigen peptides were loaded into DC to generate the nDC vaccine. Thevaccine was administered subcutaneously for 5-6 doses at 1 310^7 cells following concomitant radiotherapy plus temozolomide. The primary objective is safety. Secondary objectives includesurvival outcomes and T cell immune response against the neoantigens. Results: As of Dec. 31, 2023, eleven patients completed at least one dose of vaccination and were included in the safetyanalysis; eight patients completed planned doses and were included in the efficacy analysis. All the patients reported Treatment-emergent adverse events (TEAEs). Most TEAEs were grade 1 or 2. One patient reported two grade 3 TEAEs: decreased white blood cell count anddecreased lymphocyte count. Pyrexia was considered as treatment-related adverse event(TRAE) that was reported in two (18.2%) patients. No treatment-related deaths occurred.Among eight efficacy-assessable patients, seven (87.5%) patients kept progression-free for atleast 5.4-27.3 months; one patient progressed at 10.2 months after surgery and achievedcomplete remission after receiving anti-PD1 plus bevacizumab therapy; compared to thebaseline level, a median 15-fold (3 to 506-fold) increase of neoantigen-specific cytotoxic T cells was detected in their peripheral blood samples post-vaccination, indicating strong anti- tumor T cell responses elicited by the nDC vaccine. Conclusions: The nDC vaccine, combined with the standard treatments for GBM, was well tolerated. Initial results from this ongoingstudy have exhibited encouraging survival outcome of the nDC vaccine for patients with newly-diagnosed GBMs. Clinical trial information: NCT04968366. Research Sponsor: None. Efficacy (n=8)Treatment-Emergent Adverse Events (n=11) All GradesGrade 3 Progression-free status* 7 (87.5%) Hypercholesterolemia 5 (45.5%)0 Alive status* 8 (100%) Decreased white blood cell count4 (36.4%)1 Stable disease status* 8 (100%) Decreased lymphocyte count 4 (36.4%)1 12-month progression-free survival80% (95% CI: 51.6~100%)Hypertriglyceridemia 4 (36.4%)0 12-month overall survival 100% (95% CI: 100~100%)Hyperchloremia 4 (36.4%)0 Median progression-free survivalNot reached Hyperphosphatemia 3 (27.3%)0 Median overall survival Not reached Hyperglycemia 3 (27.3%)0 Pyrexia 2 (18.2%)0 *As of Dec. 31, 2023.CENTRAL NERVOUS SYSTEM TUMORS Downloaded from ascopubs.org by 190.236.76.167 on December 10, 2024 from 190.236.076.167 Copyright © 2024 American Society of Clinical Oncology.