Genocea Biosciences, Inc. announced to present initial clinical data on the first five patients from Part B of the ongoing Phase 1/2a study, which explores the combination of Genocea’s neoantigen vaccine, GEN-009 and checkpoint inhibitor-based regimens (CPI) in advanced solid tumors. The trial combines GEN-009 with a Standard of Care (SOC) CPI-based regimen approximately four months after the SOC CPI-based regimen is started. The preliminary findings from the first five patients show three achieving independent RECIST responses starting from the first GEN-009 dose. These responses show an acceleration of shrinkage beyond that of the CPI regimen, creating a novel response plot that supports the effect being attributable to the addition of GEN-009. One such patient achieved a complete response, while two demonstrated partial responses (“PR”). Overall, two of the first five patients achieved CRs and three experienced PRs. These results are corroborated by the patients’ immune responses. Neoantigen-specific CD4+ and CD8+ T cell responses were detected in 100% of patients, with all patients responding to multiple vaccinated antigens. Early comparison of T cell responses post-checkpoint (pre-vaccination) and post-vaccination show that T cell responses are specific to GEN-009 and not augmented by checkpoint blockade.