BACKGROUND Primary therapy for high-risk bladder cancer (BCa) is repeated instillations of the tuberculosis vaccine Bacillus Calmette-Guérin (BCG). Although BCG reduces the risk of recurrence by more than half, the mechanisms underlying its immune-activating effects remain unknown. Our objective was to investigate how the immune response differs between BCG responders and nonresponders and to compare systemic and local immune responses.METHODS We performed scRNA-seq of isolated immune cells adjacent to high-risk bladders in BCG responders and nonresponders before and after BCG. We also compared concurrent scRNA-seq profiles of circulating immune cell populations with those of bladder immune cells.RESULTS We observed an increase in Th17-like Th1 cells in BCG responders, characterized by greater expression of proinflammatory cytokines. By contrast, nonresponders showed increased CD8+ T cell exhaustion and Treg cells. We found that the primary mechanism driving divergent T cell activity is altered polarization and immunosuppressive signaling with myeloid cells. Using a machine learning–based approach, we identified that Th17-like Th1 cytokines, such as IL-17, IL-21, and IL-26, are predictive of response, which was subsequently validated in a separate BCG-treated BCa cohort.CONCLUSION Together, these findings suggest that dynamic regulation of myeloid–T cell interactions can be critical for outcomes of BCG-treated BCa.FUNDING BX005599 and BX003692 (Veterans Health Administration), HT94252410507 (Department of Defense), R01CA298333 (National Cancer Institute), and Robert H. Lurie Comprehensive Cancer Center H Foundation Core Facility Pilot Project Award.
Ryan J. Brown, Mairah T. Khan, Andrew J. Houston, Hongshen Niu, Joseph R. Podojil, Bonnie Choy, Weiguo Cui, Joshua J. Meeks
Opposing Th17 and Treg signatures define response to BCG.