Background: DN24-02 is an autologous cellular immunotherapy consisting of antigen-presenting cells (APC) cultured with BA7072, a recombinant HER2-derived antigen (HER500) linked to granulocyte macrophage colony-stimulating factor. NeuACT (NCT01353222) is an open-label, randomized, phase 2 trial of adjuvant DN24-02 or standard of care (SOC) surveillance in HER2+ urothelial cancer pts with high relapse risk after surgery. Study objectives were overall survival (OS), disease recurrence-free survival (DRFS), product potency, and immunologic response. Methods: Pts expressing HER2 were randomized 1:1 to DN24-02 or SOC (target = 180 pts). DN24-02 pts received infusions every 2 wk (for a total of 3). Product potency was assessed using CD54 upregulation as a measure of APC activation. Antigen-specific cellular response was evaluated by T cell proliferation and IFN-γ ELISPOT; humoral response was measured by ELISA. OS and DRFS were compared using Cox regression analysis. Results: In 142 enrolled pts with 13.2 mo of follow-up, OS was 37.0 (DN24-02) vs 22.2 mo (SOC) (hazard ratio [HR] 0.96; p = 0.87), and DRFS was 11.9 (DN24-02) vs 10.1 mo (SOC) (HR 0.99; p = 0.97). In subgroup OS analyses, more favorable HRs were observed in pts with lower disease burden (i.e., lack of lymph node involvement), no prior neoadjuvant chemotherapy, and lower neutrophil/lymphocyte ratios. DN24-02 increased APC activation, in vitro IL-2 and IFN-γ accumulation, serum cytokines (IL-2, IFN-γ, and TNF-α), and antigen-specific T cell responses. BA7072 and HER500 antibody titers were significantly elevated from baseline through month 16. Conclusions: No statistical differences were observed in OS or DRFS; however, interpretation of these results is restricted by limited enrollment and short follow-up. Pts with certain characteristics of lower tumor burden had the most notable HRs for OS. APC activation and cytokine patterns were consistent with an immune prime boost. DN24-02–induced immune response persisting > 1 y suggests T cell activation and immune memory generation, consistent with mobilized antitumor immune responses. Together, these results suggest that additional investigation may be warranted. Clinical trial information: NCT01353222