Bladder Cancer Journal Vol. 5 Issue 2

The Role of Myeloid Derived Suppressor Cells in Urothelial Carcinoma Immunotherapy

Myeloid derived suppressor cells (MDSC) are immune cells that dampen immune responses. In patients with cancer, MDSC are associated with adverse oncologic outcomes and therapeutic resistance. Pre-clinical evidence suggests that MDSC suppress anti-tumor immune responses. In this report, the biologic functions of MDSC are defined and evidence linking MDSC with the response to cancer immunotherapies in solid tumors are reviewed. Associations of MDSC in clinical bladder cancer cohorts are outlined in addition to evaluation of the suggested roles of MDSC in pre-clinical bladder cancer models. Human clinical trials that investigate possible MDSC modulators are highlighted, and therapeutic strategies to leverage MDSC biology in bladder cancer immunotherapy are outlined.

Evaluation of Hematuria in a Large Public Health Care System

Background: Hematuria is the most common presenting symptom in bladder cancer, but many patients are not adequately evaluated. Objectives: To evaluate the type and frequency of hematuria evaluation in a large public health care system. Patients and Methods: Electronic medical records of adult patients with urinalysis positive for hematuria (≥3 RBCs/HPF) from January 2015 to April 2018 in an outpatient setting were reviewed. Logistic regression was performed to determine factors associated with urology referral and complete evaluation. Results: 11,422 patients met the inclusion criteria; the majority were females (72%) and white race (60%). There were an additional 3,221 patient’s with initial diagnosis of UTI. Median age was 49.0 years. Testing included repeat urinalysis (50%), imaging (26%), urology referral (11.4%), cystoscopy (4.4%) and complete evaluation defined as cystoscopy and US/CT/MRI (4%). In the multivariable analysis, factors independently associated with higher referral to urology were age >35, male gender, hypertension, RBCs ≥20. African American race was associated with less referral to urology. Smoking was a significant variable on univariable analysis only. 37 patients (0.25%) were diagnosed with urological malignancies, with bladder cancer in 33, 12 of whom are missed by excluding UTI patients. Conclusions: In the outpatient setting of a public health care system, the vast majority of patients with hematuria are not referred and evaluated properly across all age categories and regardless of smoking status. This might result in missed cancer diagnoses and requires quality improvement measures.

Background: The activity of PD-1/PD-L1 inhibitors in the treatment of advanced bladder cancer (BC) is promising for many patients. However, a subset of patients do not benefit from treatment, thus leading to an effort to better identify predictive molecular biomarkers of response. Objective: To conduct a systematic review of the literature on predictive molecular biomarkers associated with response to PD-1 and PD-L1 inhibitors in advanced bladder cancer, defined as locally-advanced, unresectable, or metastatic (mBC) disease. Methods: A search of the literature was performed using Embase (1947 – January 2019), Medline (1946 – January 2019), and EBM Reviews for Cochrane Central Register of Controlled Trials (as of December 2018). Studies examining the association of molecular biomarkers with clinical outcome in BC treated with PD-1 or PD-L1 monotherapy were included. Outcomes of interest were overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS), duration of response, and objective response rate (ORR). Results: Using the study search criteria, 899 unique abstract citations were found, of which 834 did not meet the eligibility criteria. Full text of the remaining 65 citations were screened, and 50 studies excluded, including 18 review articles. Eight additional studies from the bibliography of the review papers were included, making a total of 23 studies. Five PD-1 / PD-L1 antibodies have been tested in BC immunohistochemistry (IHC). These studies used different expression scoring criteria and generally had poor ability to discriminate likelihood for response. Overall, the data suggests CD8+ T cell infiltration is necessary to mediate an antitumor immune response, but other immune cell populations, such as neutrophils may suppress T cell-mediated immunity and efficacy of PD-1/PD-L1 blockade. An IFNγ signature is a promising predictor, but there needs to be consensus on the optimal gene panel composition, and prospective validation. Tumor mutation burden (TMB) is a promising predictor in six studies reporting on 1200 patients, but there is not a consensus on the optimal definition of “high TMB”. Detection of T cell receptor (TCR) clonal expansion has only been conducted in small studies and so its predictive value remains inconclusive. Epithelial-mesenchymal transformation (EMT) and transforming growth factor β (TGFβ) are associated with poor prognosis and possibly intrinsic resistance to PD-1/PD-L1 checkpoint blockade, but more work needs to be done to build upon and confirm the initial findings. Conclusions: Currently no molecular biomarker is sufficiently mature for routine clinical use, while some candidates, or a combination show great promise and need further study. 

MRE11A Isoform Expression Associated with Outcome Following Radiotherapy in Muscle-Invasive Bladder Cancer does not Alter Cell Survival and DNA Double-Strand Break Repair Following Ionising Radiation

Background: DNA double strand breaks are the cytotoxic lesions produced by ionising radiation. Critical for the repair of these lesions is the DNA damage response protein MRE11 which, in a complex with RAD50 and NBS1, mediates DNA damage signalling and double-strand break repair. We previously found the presence of an MRE11 germline single nucleotide polymorphism (SNP), rs1805363 (G  > A), to be associated with poor outcome following radiotherapy (RT) and increased expression of MRE11 isoform 2 in a limited panel of bladder cancer cell lines and tumours. Objectives: To look for further evidence in support of the SNP/isoform association in a larger panel of germline and tumour samples donated by patients diagnosed with invasive bladder cancer, and to test the hypothesis that bladder cancer cells expressing MRE11 isoform 2 would be more radio resistant than cells expressing MRE11 isoform 1. Methods: Germline DNA from 189 patients with invasive bladder cancer (141 T2, 48 T1) was genotyped for the rs1805363 G  > A SNP. Loss of heterozygosity was determined by genotyping tumour DNA in 17GA germline patients. The Cancer Genome Atlas was mined to correlate presence of the GA germline genotype with MRE11 isoform expression. We used colony formation assays and γ H2AX foci kinetics after ionising radiation in RT112 MRE11 knockdown cells expressing ectopic MRE11 isoform 1 or 2. Results: Of the 189 germline DNA samples, 22 contained both the A minor allele and G major allele with the remaining wild type containing only the G major allele. LOH was identified in seven of 17 available tumour samples. Tumour MRE11 isoform 2 expression was found to be significantly higher (p  = 0.007) in patients’s samples containing the A minor allele compared to those with only the G major allele (n  = 23). In the TCGA database we found 16% (66 out of 406) of bladder tumours heterozygous for the SNP and only two homozygous, and a significant relative increase of isoform 2 usage (p  = 0.017). We identified no significant difference in radio sensitivity between bladder cancer cells expressing either MRE11 isoform. Conclusions: In this study the MRE11 isoform 2 was not found to be associated with increased cellular sensitivity to radiation. We conclude that the previously reported association between the germline rs1805363 SNP and poor survival in MIBC patients following RT is unlikely to be related to the DNA damage response function of MRE11 isoform 2. 

Background: Major interest lies in the evaluation of immune infiltrate in bladder cancer. CD8+ cytotoxic lymphocytes are key effectors of adaptive immune response. Objectives: The aims of the study were to set up a standardized methodology for CD8+ lymphocytes estimation in NMIBC and investigate how intra-tumoral heterogeneity influences CD8+ immune infiltrate. Methods: We considered 995 NMIBC included in the Spanish Bladder Cancer (SBC)/EPICURO Study. Duplicate 0.6 mm TMA spots and paired full sections (FS) for 50 selected cases were double stained with anti-pan cytokeratin antibody and anti-CD8 antibody. Slides were digitalized and CD8+ cells were automatically counted after tissue recognition (tumor vs stroma). Spatial heterogeneity was assessed and a resampling strategy was applied to estimate the proper number of 0.6 mm TMA spots providing an adequate CD8+ cell estimate. Association between CD8+ count and expression of urothelial differentiation markers was estimated. Cox regression models were performed to assess association between CD8+ cell count and risk of recurrence and progression. Results: Microscopic examination of full sections showed spatial heterogeneity for CD8+ infiltrates. Simulation analyses demonstrated that 5 TMA regions provided a correct sampling of tumor and stromal compartments in Ta while 2 and 6 TMA regions were necessary in T1, respectively. CD8+ cells infiltration was associated with stage, regardless of the histological compartment analyzed (median CD8 + /mm2 were 25/mm2 and 129/mm2 in tumor and stroma respectively in Ta and 111/mm2 and 344/mm2 in T1; p -value = 0.006). CD8+ infiltration in tumor compartment was significantly associated with low FGFR3 expression. CD8 + /mm2 count in the tumor compartment was not associated with prognosis. Conclusion: Differences identified between Ta and T1 tumours supported the hypothesis that rigorous efforts should be placed in proper study design. These results provide a new framework to investigate microenvironment complexity in bladder cancer. 

A Clinical Trial of the Intradermal TLR2 Agonist CADI-05 for BCG Recurrent and Unresponsive Non-Muscle Invasive Bladder Cancer

Background: CADI-05, a TLR-2 agonist, induces Th1 immune response following intradermal administration and has been found useful in management of lung cancer and melanoma. Objective: To evaluate CADI-05 in patients with BCG recurrent and unresponsive Non-muscle invasive bladder cancer (NMIBC) for 15-months recurrence free survival (RFS) rate. Methods: In BCG unresponsive (BU) or recurrent (BR) NMIBC, CADI-05 was administered intradermally every two weeks for 3 months followed by every month for 3 months and subsequently every 2 months for 6 months following transurethral resection (TUR) in a single arm study (ClinicalTrials.gov: NCT00694798). Cystoscopy, cytology, and sonography were performed for the presence/recurrence of NMIBC at 3, 6, 9, 12, 15 months and beyond and confirmed by biopsy. Evaluation of preoperative biopsy for Desmocollin-3 (DSC3) expression and tumor infiltrating lymphocytes (TIL) was optional. Results: Twenty patients with NMIBC received intradermal CADI-05. RFS at 15 and 30 months was 35% (7/20) patients. The median RFS was also better for BU compared to BR group (HR, 0.329; 95% CI, 0.071 to 1.532). DSC3 expression was present in 68.8% (11/16) patients. TIL and RFS beyond 30 months were seen 2.3 times and 2.8 times more often in DSC3 expressing NMIBC respectively. No grade IV or V adverse events occurred. Local site reactions were the most common adverse event. Conclusion: Intradermal CADI-05 following TUR is associated with 35% RFS at 30 months. 

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