Neon Therapeutics, Inc. presented updated data describing the immune and pathologic markers associated with durable clinical benefit in patients enrolled in NT-001, an ongoing Phase 1b clinical trial evaluating NEO-PV-01 in combination with nivolumab (OPDIVO® or anti-PD-1 therapy). The data were highlighted in an oral presentation titled, 'The Personalized Vaccine, NEO-PV-01 with Anti-PD-1, Induces Neoantigen-Specific De Novo Immune Responses in Patients with Advanced or Metastatic Melanoma: Association with Clinical Outcomes', at the American Association for Cancer Research (AACR) Annual Meeting in Atlanta. NEO-PV-01 is a personal neoantigen vaccine custom-designed and manufactured based on the neoantigens identified by Neon’s proprietary bioinformatics engine, RECON®, as being the most therapeutically relevant for an individual patient. The data presented now, which reflect a cutoff date of August 31, 2018, include 23 patients with metastatic melanoma who received at least one dose of NEO-PV-01 and who either remained progression-free or had progressed by week 36 after the initiation of anti-PD-1 therapy. Patients who did not progress by 36 weeks were classified as having durable clinical benefit (DCB). The data indicate that RECON-based prediction of neoantigen quality correlates with DCB and serves as clinical validation for RECON’s ability to identify therapeutically relevant neoantigens. The analysis presented at AACR both confirms mechanism of action of NEO-PV-01 and highlights new data on the relationships between multiple histological and molecular markers and DCB in the melanoma cohort. Together these findings show that: RECON-based prediction of high-quality neoantigens was correlated with DCB; Durable, neoantigen-specific peripheral immune responses were found only post-vaccine; Vaccine-induced T cells trafficked to the tumor and were capable of killing tumor cells; In patients tested, epitope spread was detected in all patients with DCB and only post vaccine; Post-vaccine biopsies showed marked reduction in tumor content, which was associated with DCB; Tumor microenvironment analysis indicated that major histocompatibility complex class II expression, B cell gene signature, a natural killer cell gene signature and TCF7-positive CD8 cells were all correlated with DCB, and may play an important role for patient selection in future studies; and Several metrics that typically correlate with patient response to checkpoint inhibitors, including tumor mutation burden and tumor PD-L1, were not correlated with DCB in this analysis.