Myeloid-derived suppressor cells and tolerogenic dendritic cells are distinctively induced by PI3K and Wnt signaling pathways.

Imbalanced immune responses are a prominent hallmark of cancer and autoimmunity. Myeloid cells can be overly suppressive, inhibiting protective immune responses or inactive not controlling autoreactive immune cells. Understanding the mechanisms that induce suppressive myeloid cells, such as myeloid-derived suppressor cells (MDSCs) and tolerogenic dendritic cells (TolDCs), can facilitate the development of immune-restoring therapeutic approaches. MDSCs are a major barrier for effective cancer immunotherapy by suppressing antitumor immune responses in cancer patients. TolDCs are administered to patients to promote immune tolerance with the intent to control autoimmune disease. Here, we investigated the development and suppressive/tolerogenic activity of human MDSCs and TolDCs to gain insight into signaling pathways that drive immunosuppression in these different myeloid subsets. Moreover, monocyte-derived MDSCs (M-MDSCs) generated in vitro were compared to M-MDSCs isolated from head-and-neck squamous cell carcinoma patients. PI3K-AKT signaling was identified as being crucial for the induction of human M-MDSCs. PI3K inhibition prevented the downregulation of HLA-DR and the upregulation of reactive oxygen species and MerTK. In addition, we show that the suppressive activity of dexamethasone-induced TolDCs is induced by ß-catenin-dependent Wnt signaling. The identification of PI3K-AKT and Wnt signal transduction pathways as respective inducers of the immunomodulatory capacity of M-MDSCs and TolDCs provides opportunities to overcome suppressive myeloid cells in cancer patients and optimize therapeutic application of TolDCs. Lastly, the observed similarities between generated- and patient-derived M-MDSCs support the use of in vitro-generated M-MDSCs as powerful model to investigate the functionality of human MDSCs.

Predictors of local recurrence and its impact on survival after glansectomy for penile cancer: time to challenge the dogma?

OBJECTIVES: To identify predictive pathological factors for local recurrence (LR) and to study the impact of LR on survival in patients treated with glansectomy for penile squamous cell carcinoma (pSCC). PATIENTS AND METHODS: We retrospectively studied patients treated with glansectomy at international, high-volume reference centres. We analysed histopathological predictors of LR, stratified patients into risk groups based on the number of risk factors present, and studied the impact of LR on survival outcomes using Kaplan-Meier survival analysis and stepwise Cox proportional hazards regression models. Subsequently, we performed sensitivity analyses excluding margin-positive cases, pT3 disease, and cN+ disease, or all of these factors. RESULTS: Across nine institutions, 897 patients were included, of whom 94 experienced LR. On multivariable analysis, presence of high-grade disease and pT3 stage were independent predictors of LR. LR-free survival rates significantly differed according to the number of risk factors present, with a hazard ratio (HR) of 1.90 (95% confidence interval [CI] 1.17-3.07; P = 0.01) for the intermediate-risk group (one risk factor) and 6.11 (95% CI 3.47-10.77; P < 0.001) for the high-risk group (two risk factors), using the low-risk group (no risk factors) as reference. Patients who experienced LR had significantly worse overall survival (OS; HR 2.89, 95% CI 2.02-4.14; P < 0.001) and cancer-specific survival (CSS; HR 5.64, 95% CI 3.45-9.22; P < 0.001). LR (HR 3.82, 95% CI 2.14-6.8; P < 0.001), lymphovascular invasion and cN status were significant predictors of decreased CSS. LR remained a strong predictor of both OS and CSS in all sensitivity analyses. CONCLUSIONS: Pathological T3 stage and presence of high-grade disease were independent histopathological predictors of LR after glansectomy for primary pSCC, which allowed risk stratification into three groups with significantly different risk of developing LR. Additionally, LR is related to poor OS and CSS, indicating that LR is a manifestation of underlying aggressive disease and clearly challenging the dogma of using organ-sparing surgery whenever possible since survival is unaffected by higher LR rates.