Effects of combined radiotherapy with immune checkpoint blockade on immunological memory in luminal-like subtype murine bladder cancer model.

MIBC is a highly lethal disease, and the patient survival rate has not improved significantly over the last decades. UPPL is a cell line that can be used to recapitulate the luminal-like molecular subtype of bladder cancer and to discover effective treatments to be translated in patients. Here, we investigate the effects of combinational treatments of radiotherapy and immunotherapy in this recently characterized UPPL tumor-bearing mice. We first characterized the baseline tumor microenvironment and the effect of radiation, anti-PD-L1, and combinatorial treatments. Then, the mice were re-challenged with a second tumor (rechallenged tumor) in the contralateral flank of the first tumor to assess the immunological memory. Radiation slowed down the tumor growth. All treatments also decreased the neutrophil population and increased the T cell population. Anti-PD-L1 therapy was not able to synergize with radiation to further delay tumor growth. Furthermore, none of the treatments were able to generate immune memory. The treatments were not sufficient to induce a significant and lasting pool of memory cells. We show here that anti-PD-L1 treatment added to radiotherapy was not enough to achieve T cell-mediated memory in UPPL tumors. Stronger T cell activation signals may be required to enhance radiation efficacy in luminal-like bladder cancer.

Impact of Programmed Death-ligand 1 Expression on Oncological Outcomes in Patients with Muscle-invasive Bladder Cancer Treated with Radiation-based Therapy.

Background: No biomarkers are recommended for patients undergoing radiation-based therapy (RT) for muscle-invasive bladder cancer (MIBC). Objective: We aim to evaluate the predictive role of programmed death-ligand 1 (PD-L1) expression on the oncological outcomes of patients treated with RT for MIBC. Design setting and participants: A single-center retrospective analysis of tumor specimens collected through transurethral resection (TURBT) from 104 MIBC patients, implemented in a tissue microarray and stained with the SP263 PD-L1 clone (Ventana Medical Systems, Tucson, AZ, USA), was conducted. Two reviewers measured the PD-L1 H-score for tumor and immune cells. Intervention: RT (maximal TURBT followed by radiation and concurrent chemotherapy when eligible). Outcome measurements and statistical analysis: Logistic and Cox regression models were used to predict 3-mo complete response (CR) and overall survival (OS) after RT, respectively. Results and limitations: A total of 88 (85%) patients had cT2 disease and 39 (37.5%) had high immune cell PD-L1 expression. A CR was achieved in 68 (65%) patients. On the multivariable analysis (MVA), a higher clinical stage (p = 0.02) and a low immune cell PD-L1 H-score (p = 0.02) were associated with a decreased CR after RT. The median time to death was 43 mo (95% confidence interval 20-66). On Cox MVA, a high immune cell PD-L1 H-score (p = 0.0017) was associated with better OS, independently of performance status (p = 0.0005) or tumor stage (p = 0.0013). A high tumor cell PD-L1 H-score was not an independent predictor of CR or OS. Limitations of the study include the retrospective design. Conclusions: MIBC patients with high PD-L1 expression on immune cells appear to have better oncological outcomes following RT. Our results may aid in patient stratification for future clinical trial design. Patient summary: In this report, we evaluated the role of programmed death-ligand 1 (PD-L1) expressed on tumor and immune cells in the tumor microenvironment for patients treated with a bladder-sparing regimen. We found that PD-L1 overexpression on immune cells is able to predict a better response to radiation-based therapy.

Role of Serum Lymphocyte-derived Biomarkers in Nonmetastatic Muscle-invasive Bladder Cancer Patients Treated with Trimodal Therapy.

BACKGROUND: The role of serum lymphocyte-based biomarkers, such as the neutrophil-to-lymphocyte (NLR), lymphocyte-to-monocyte (LMR), and platelet-to-lymphocyte (PLR) ratios, was previously studied in patients with muscle-invasive bladder cancer (MIBC) treated with radical cystectomy but remains underexplored in patients treated with trimodal therapy (TMT). OBJECTIVE: To analyze the impact of serum lymphocyte-based biomarkers on main oncological outcomes after TMT for MIBC. DESIGN SETTING AND PARTICIPANTS: A retrospective study, including 176 patients treated with TMT for nonmetastatic MIBC (cT2-4/cN0-2) between 2001 and 2017 at a tertiary academic center, was conducted. INTERVENTION: TMT, consisting of initial maximal transurethral resection of the bladder tumor, followed by radiotherapy with concurrent chemotherapy. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Clinicopathological characteristics, serum laboratory tests, and imaging reports were collected. NLR, LMR, and PLR were calculated before and at the end of TMT. Dynamic patterns of NLR, LMR, and PLR during TMT were studied. Multivariable regression models were performed to estimate the effect of these biomarkers on complete response (CR) to TMT and survival. RESULTS AND LIMITATIONS: The median age was 75 yr (interquartile range 66-82). Staging was cT2 in 156 (89%) and cN0 in 159 (90%) patients. A pretreatment NLR (pre-NLR) of ≥4.0 was independently associated with lower CR rates (odds ratio 0.32; p = 0.013). In addition, a pre-NLR of ≥4.0 was associated with worse cancer-specific survival (hazard ratio [HR] 1.88; p = 0.032) and overall survival (OS; HR 1.61; p = 0.033) together with other factors such as hydronephrosis, Eastern Cooperative Oncology Group performance status, and cT stage 3-4a. When both pre- and post-treatment variables were considered, an increase in NLR beyond 75% during TMT (HR 1.63; p = 0.035) was associated with worse OS. This study was limited by its retrospective design. CONCLUSIONS: A high pre-NLR value was independently associated with lower rates of CR and worse survival in MIBC patients undergoing TMT. Prospective validation is needed to implement NLR into clinical practice. PATIENT SUMMARY: In this study, we reported the oncological outcomes of patients with muscle-invasive bladder cancer treated with trimodal therapy. We found that the neutrophil-to-lymphocyte ratio, a cheap and available blood-derived biomarker, was associated with response to trimodal therapy and survival outcomes.

Role of neutrophil extracellular traps in radiation resistance of invasive bladder cancer.

Radiation therapy (RT) is used in the management of several cancers; however, tumor radioresistance remains a challenge. Polymorphonuclear neutrophils (PMNs) are recruited to the tumor immune microenvironment (TIME) post-RT and can facilitate tumor progression by forming neutrophil extracellular traps (NETs). Here, we demonstrate a role for NETs as players in tumor radioresistance. Using a syngeneic bladder cancer model, increased NET deposition is observed in the TIME of mice treated with RT and inhibition of NETs improves overall radiation response. In vitro, the protein HMGB1 promotes NET formation through a TLR4-dependent manner and in vivo, inhibition of both HMGB1 and NETs significantly delays tumor growth. Finally, NETs are observed in bladder tumors of patients who did not respond to RT and had persistent disease post-RT, wherein a high tumoral PMN-to-CD8 ratio is associated with worse overall survival. Together, these findings identify NETs as a potential therapeutic target to increase radiation efficacy.

PD-1/PD-L1 Immune Checkpoint Inhibition with Radiation in Bladder Cancer: In Situ and Abscopal Effects.

The combination of radiation with immune checkpoint inhibitors was reported in some cancers to have synergic effects both locally and distally. Our aim was to assess this combined therapy on both radiated and nonradiated bladder tumors and to characterize the immune landscape within the tumor microenvironment. Murine bladder cancer cells (MB49) were injected subcutaneously in both flanks of C57BL/6 mice. Mice were randomly assigned to the following treatments: placebo, anti-PD-L1 (four intraperitoneal injections over 2 weeks), radiation to right flank (10 Gy in two fractions), or radiation+anti-PD-L1. Tumor digestion, flow cytometry, and qPCR were performed. Log-rank analysis was used for statistical significance. Radiation+anti-PD-L1 group demonstrated statistically significant slower tumor growth rate both in the radiated and nonirradiated tumors (P < 0.001). Survival curves demonstrated superior survival in the combination group compared with each treatment alone (P = 0.02). Flow cytometry showed increased infiltration of immunosuppressive cells as well as CTL in the radiation and combination groups (P = 0.04). Ratio of immunosuppressive cells to CTL shifted in favor of cytotoxic activity in the combination arm (P < 0.001). The qPCR analysis revealed downregulation of immunosuppressive genes (CCL22, IL22, and IL13), as well as upregulation of markers of CTL activation (CXCL9, GZMA, and GZMB) within both the radiated and distant tumors within the combination group. Combining radiation with immune checkpoint inhibitor provided better response in the radiated tumors and also the distant tumors along with a shift within the tumor microenvironment favoring cytotoxic activity. These findings demonstrate a possible abscopal effect in urothelial carcinoma with combination therapy.

The immune mediated role of extracellular HMGB1 in a heterotopic model of bladder cancer radioresistance.

Radical cystectomy (RC) together with bilateral pelvic lymph node dissection remains the standard treatment for muscle invasive bladder cancer (MIBC). However, radiation-based treatments such as tri-modal therapy (TMT) involving maximally performed transurethral resection of bladder tumor (TURBT), radiotherapy (XRT), and a chemosensitizer represent an attractive, less invasive alternative. Nevertheless, 25-30% of MIBC patients will experience local recurrence after TMT and half will develop metastasis. Radioresistance of tumor cells could potentially be one of the causes for local recurrence post treatment. High mobility group box-1 (HMGB1) was shown to play a role in bladder cancer radioresistance through its intracellular functions in promoting DNA damage repair and autophagy. Recently, HMGB1 was found to be passively released from irradiated tumor cells. However, less is known about the involvement of extracellular HMGB1 in impairing radiation response and its exact role in modulating the tumor immune microenvironment after XRT. We identified a novel mechanism of bladder cancer radioresistance mediated by the immunological functions of HMGB1. The combination of radiation plus extracellular HMGB1 inhibition markedly improved the radiation response of tumors and resulted in marked changes in the immune landscape. Moreover, combining radiation and HMGB1 inhibition significantly impaired tumor infiltrating MDSCs and TAMs -but not Tregs- and shifted the overall tumor immune balance towards anti-tumoral response. We conclude that extracellular HMGB1 is involved in bladder cancer radioresistance through promoting pro-tumor immune mechanisms.