Combination of a CCL21-gene modified dendritic cell vaccine and pembrolizumab induces immune responses in non-small cell lung cancer [Bulk TCR-seq]

We report results from a phase I trial combining intratumoral administration of a CCL21-gene modified dendritic cell (CCL21-DC) vaccine with pembrolizumab in patients with advanced NSCLC. Among 23 patients that received trial therapy, there were no dose-limiting toxicities and a low incidence of treatment-related adverse events.

Although no objective responses were observed, 36.8% of patients had a best response of stable disease (SD). Correlative analyses of longitudinal tumor biopsies revealed that disease stability was associated with reduced tumor mutational heterogeneity and increased intratumoral T cell receptor diversity following therapy. Post-treatment tumor biopsies exhibited increased CD4+ T cell infiltration and the presence of novel T cell clones that predominantly possessed CD4+ memory T cell phenotypes.