Decreased T-Cell Programmed Death Receptor-1 Expression in Pregnancy-Associated Melanoma.

INTRODUCTION: Pregnancy depends on tolerance of an immunologically foreign fetus through type 1 T-cell suppression. Worse melanoma outcomes have been described within 1 year of childbirth. We assessed immunopathologic factors that may account for the observed negative impact of pregnancy on outcome. MATERIALS AND METHODS: Women of child-bearing age with ≥24 months follow-up were identified from our Institutional Melanoma Registry. Women with available primary tumor blocks were compared [history of childbirth within 1 year of diagnosis (CB1Y) (n = 18) vs. nonpregnant age-matched controls (n = 13)]. Immunohistochemical staining with quantification of immune infiltrates: CD68 tumor-associated macrophages, CD3 tumor-infiltrating T cells, and PD-1 activated/exhausted T cells; and hematolymphangiogenesis: CD31/D2-40 blood vessels and D2-40 lymphatics was performed by 2 blinded dermatopathologists. RESULTS: CB1Y tumors showed decreased CD3 tumor-infiltrating T cells (P < 0.05) with significantly reduced PD1 expression (P ≤ 0.05). The CD3:PD1 ratio was higher in CB1Y (P < 0.05). Other tested parameters did not significantly differ between the 2 groups. DISCUSSION: As PD1 expression is induced during type 1 T-cell activation, these data suggest that immune ignorance or suppression may predominate in CB1Y. Further studies are required to identify interventions that may promote tumor-associated T-cell inflammation in such patients.

Challenges faced when identifying patients for combination immunotherapy.

In 1996, Jim Allison demonstrated that blocking the immune regulatory molecule CTLA-4 with anit-CTLA4 antibody led to enhance tumor responses in mice. It would take an additional 15 years for human studies to confirm the potency and clinical efficacy of anti-CTLA4, ultimately leading to US FDA approval of the first checkpoint inhibitor, ipilimumab. Now with a plethora of immune-modulating agents demonstrating single agent safety and benefit across many tumor types, investigation on the optimal combination of immune-based therapies has begun in earnest. While there are many challenges, a central one is how to select which combination for which patient is the best. Here we review the current approaches that a practitioner can use to achieve this therapeutic goal.

A human promyelocytic-like population is responsible for the immune suppression mediated by myeloid-derived suppressor cells.

We recently demonstrated that human BM cells can be treated in vitro with defined growth factors to induce the rapid generation of myeloid-derived suppressor cells (MDSCs), hereafter defined as BM-MDSCs. Indeed, combination of G-CSF + GM-CSF led to the development of a heterogeneous mixture of immature myeloid cells ranging from myeloblasts to band cells that were able to suppress alloantigen- and mitogen-stimulated T lymphocytes. Here, we further investigate the mechanism of suppression and define the cell subset that is fully responsible for BM-MDSC-mediated immune suppression. This population, which displays the structure and markers of promyelocytes, is however distinct from physiologic promyelocytes that, instead, are devoid of immuosuppressive function. In addition, we demonstrate that promyelocyte-like cells proliferate in the presence of activated lymphocytes and that, when these cells exert suppressive activity, they do not differentiate but rather maintain their immature phenotype. Finally, we show that promyelocyte-like BM-MDSCs are equivalent to MDSCs present in the blood of patients with breast cancer and patients with colorectal cancer and that increased circulating levels of these immunosuppressive myeloid cells correlate with worse prognosis and radiographic progression.

Blood Myeloid-Derived Suppressor Cells Correlate with Neutrophil-to-Lymphocyte Ratio and Overall Survival in Metastatic Urothelial Carcinoma.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) were linked to pathologic stage in bladder urothelial carcinoma (UC). Neutrophil lymphocyte ratio (NLR) is an inflammatory biomarker with a prognostic role in metastatic (m)UC. OBJECTIVE: We hypothesized that MDSC levels correlate with NLR and overall survival (OS) in mUC. PATIENTS AND METHODS: MDSCs were measured in blood samples from patients with mUC in fresh unfractionated whole blood (WB) and peripheral blood mononuclear cells (PBMC) by flow cytometry and defined as LinloCD33+/HLADR- (Total MDSC). MDSC subsets were defined as polymorphonuclear (PMN-MDSC: CD15+/CD14-), monocytic (M-MDSC: CD15-/CD14+), and uncommitted (UNC-MDSC: CD15-/CD14-). MDSC populations were presented as a percentage of live nucleated blood cells. Spearman's rank correlation assessed correlations between MDSC and NLR. Kaplan-Meier curves and log-rank test estimated OS from the time of MDSC collection to last follow-up or date of death. RESULTS: Of the 76 patients, 78% were men and 43% were never smokers with a median age of 69 years (range 31-83); 72% had pure UC and 76% had lower tract UC. Prior therapies included intravesical therapy (22%), neoadjuvant chemotherapy (30%), cystectomy or nephroureterectomy (55%). Median follow-up for all patients was 12 months (0.6-36.5). PMN-MDSC was the predominant subset in WB and PBMC. There was significant correlation between individual MDSC subsets in WB and PBMC (p ≤ 0.001). Both WB UNC-MDSC/PMN-MDSC ratios (rho = - 0.27, p = 0.03) and PBMC UNC-MDSC/PMN-MDSC (rho = - 0.28, p = 0.02) were negatively correlated with NLR. Median OS was 17.7 months (95% CI: 11.0-NE). Overall 1-year and 3-year survival rates were 0.60 (95% CI 0.49-0.73) and 0.15 (95% CI 0.03-0.67), respectively. Higher WB UNC-MDSC levels (HR 3.78, p = 0.0022) and higher NLR (HR 2.6, p = 0.0179) were associated with shorter OS. CONCLUSIONS: Specific MDSC subsets correlate with NLR. Higher WB UNC-MDSC levels and higher NLR were negative prognostic factors. Given the feasibility of serial blood draws, dynamic assessment of MDSC over time and further validation with longer follow-up are warranted.

Myeloid-Derived Suppressor Cells in Nonmetastatic Urothelial Carcinoma of Bladder Is Associated With Pathologic Complete Response and Overall Survival.

BACKGROUND: Myeloid-derived suppressor cells (MDSC) have immunosuppressive activity and enhance tumor progression. We hypothesized that lower blood MDSC would correlate with pathologic complete response and better outcomes in nonmetastatic urothelial carcinoma (UC). PATIENTS AND METHODS: Before cystectomy, blood MDSC were measured in whole blood (WB) and peripheral blood mononuclear cells using flow cytometry. MDSC were defined as CD33+/HLA-DR-. MDSC subtypes were polymorphonuclear MDSC (CD15+/CD14-), monocytic (M)-MDSC (CD15-/CD14+), and uncommitted (UnC) MDSC (CD15-/CD14-). The Wilcoxon rank sum test was used to compare MDSC between pathologic complete response groups. The optimal cutoff points for MDSC were identified using recursive partitioning analysis with cross-validation. The Cox proportional hazard model was used to associate MDSC and other clinical factors with recurrence-free survival and overall survival (OS). RESULTS: Overall, 109 patients were included: 86% men with median (range) age of 67 (30-88) years, 76% with pure UC, 29% intravesical therapy, and 41% neoadjuvant chemotherapy. Twenty-one patients (19%) had pT0N0 and 23 (24%) < pT2N0. Median (range) follow-up time was 17.4 (0.4-42.4) months. Total MDSC and polymorphonuclear MDSC percentage in peripheral blood mononuclear cells was significantly lower in patients with pT0N0 disease (P = .03). One- and 2-year OS rates were 94% (95% confidence interval [CI], 90-99) and 83% (95% CI, 75-93), respectively. In the multivariate Cox model after adjusting for age and gender, patients with higher WB M-MDSC and UnC-MDSC had shorter OS (optimal cutoff points by recursive partitioning analysis, hazard ratio = 7.5 [95% CI, 2.5-22.8], P = .0004; hazard ratio = 3.4 [95% CI, 1.0-11.0], P = .046, respectively). CONCLUSION: In patients with nonmetastatic UC of bladder, higher WB M-MDSC and UnC-MDSC before cystectomy had negative prognostic value. Prospective validation is warranted.

Evaluation of T cell infiltration in matched biopsy and nephrectomy samples in renal cell carcinoma.

T cell infiltration in tumors has been investigated as a biomarker of response to checkpoint inhibitors. Neo-adjuvant studies in renal cell carcinoma (RCC) may provide a unique opportunity to compare T cell infiltration in a pretreatment renal mass biopsy to a posttreatment nephrectomy specimen, and thus evaluate the effects of immune checkpoint inhibitors. However, there are no data regarding the association of T cell infiltration in matched biopsy and nephrectomy samples without intervening treatment. Understanding this association will inform investigation of this potential biomarker in future studies.Matched biopsy and nephrectomy samples (without intervening systemic therapy) were identified from patients with nonmetastatic RCC. Selected tissue sections from biopsy and nephrectomy samples were reviewed and marked for intratumoral lymphocytes by a pathologist. Immunohistochemistry (IHC) was utilized to stain for T cell markers (CD3, CD4, and CD8). Intratumoral staining was then quantified in the tissue sections as counts per total tumor area surveyed. Spearman correlation (r) was used to measure associations.Thirty matched pairs were investigated. The median interval between biopsy and nephrectomy was 2.8 (0.2-87.7) months. Clear cell was the most common histology (29/30; 97%). There was a statistically significant positive correlation between the frequency of CD3 and CD8 T cells between matched biopsy and nephrectomy samples (r = 0.39; P = .036 and r = 0.38; P = .041, respectively).The frequencies of CD8+ T cells in matched biopsy and nephrectomy samples in RCC in the absence of intervening treatment have been characterized and show a positive correlation between matched biopsy and nephrectomy samples.

Myeloid-derived suppressors cells (MDSC) correlate with clinicopathologic factors and pathologic complete response (pCR) in patients with urothelial carcinoma (UC) undergoing cystectomy.

BACKGROUND: Myeloid derived suppressor cells (MDSC) are heterogeneous immunosuppressive cells with potential predictive and prognostic roles in cancer. The association between MDSC, clinicopathologic factors, and pathologic response in patients with bladder urothelial carcinoma (UC) was explored. METHODS: Peripheral blood or tissue were collected from patients with UC undergoing definitive surgery. MDSCs levels were measured in peripheral blood mononuclear cells and fresh tumor tissue. MDSCs were identified by flow cytometry and defined as total MDSC (T-MDSC) CD33+/HLADR-. From this population, 3 subsets were identified: polymorphonuclear-MDSC (PMN-MDSC) defined as CD33+/HLADR-/CD15+/CD14-, monocytic-MDSC (M-MDSC) defined as CD33+/HLADR-/CD15-/CD14+, and immature-MDSC (I-MDSC) defined as CD33+/HLADR-/CD15-/CD14-. MDSC populations were presented as % of live nucleated blood cells. Spearman correlations (r) and Wilcoxon rank sum test were used to assess correlations between MDSC populations, clinicopathologic factors, and pathologic complete response (pCR). RESULTS: 85 patients scheduled to undergo cystectomy from February 2015 through Dec 2016 were included. All patients had blood drawn for analysis and 23 patients had residual tumor tissue collected for analysis at the time of surgery. Of these 85, 74 (87%) were men with a median age at diagnosis of 68 (range: 44-87). Pure UC was the most common histology (75%); 28 (35%) patients had prior treatment with intravesical therapy and 36 (42%) were treated with neoadjuvant chemotherapy, primarily gemcitabine plus cisplatin (n = 24). On surgical pathology, 18 (21%) of the patients had pCR, 11 (13%) had positive lymph nodes, and 20 patients (24%) had lymphovascular invasion. Statistically significant associations were found between circulating MDSC levels and pCR rates (P<0.01), absolute neutrophil-lymphocyte ratio (P = 0.008), and histology (P = 0.01). Tumor % M-MDSCs were negatively associated with lymphovascular invasion (P = 0.04). There were no significant correlations between peripheral blood mononuclear cells and tumor MDSC subtypes. CONCLUSIONS: Blood and tissue MDSC levels correlate with several clinicopathologic factors and may predict for pCR. Future studies are needed to highlight the role of MDSC in predicting long-term outcomes and to determine the clinical implications of these findings.

Myeloid-derived suppressor cells in cancer patients: a clinical perspective.

Myeloid-derived suppressor cells (MDSCs) represent a heterogenous collection of immature myeloid cells endowed with suppressive function on the immune response. Their presence has been extensively investigated in preclinical models, especially in the context of cancer. One of the major obstacles in their accurate identification has been the definition of an unambiguous phenotype, shared between mice and humans, and clearly correlating with their suppressive function. In this paper, we review the literature concerning the phenotype in mouse and in humans, showing that at least 2 subsets of MDSCs are present under different situations. We also address the role of MDSCs in tumor progression, evaluate the prognostic significance of MDSC in cancer patients, and their possible role as marker of clinical outcome and response to therapy. Finally, we examine the strategies designed to modulate MDSCs in cancer patients, which might represent an innovative approach to enhance the effectiveness of immune-based therapies.