First-Line Chemotherapy Response Is a Predictive Factor for Immune Checkpoint Inhibitors Treatment in Advanced Urothelial Carcinoma, a Real World Retrospective Study

Background: Immune checkpoint inhibitors (ICIs) have become important tools for the treatment of advanced urothelial carcinoma (aUC). However, the clinical strategy using ICIs and chemotherapy is still controversy. The aim of this study was to evaluate the association of clinical parameters in aUC patients with ICIs treatment. Methods: We retrospectively analyzed aUC patients who received atezolizumab and pembrolizumab between January 2015 and October 2020. The associations between baseline demographics and clinical outcomes were evaluated. Results: Of the 74 included patients, the median age was 67 years. Among them, 53 patients received atezolizumab and the other 21 received pembrolizumab. There were 50 patients receiving rst line ICIs therapy and the other 24 received second line monotherapy. Fifty-two (83.87%, 52/62) received cisplatin among all chemotherapy patients. The median progression free survival was 10.94 months and the overall survival was 28.44 months. Poor chemotherapy response or no chemotherapy, liver metastases, Eastern Cooperative Oncology Group (ECOG) status and higher neutrophil/lymphocyte ratio (NLR) were associated with higher risk of diseases progression (HR=5.70, 95% CI 2.04-15.90, p=0.001, HR=6.08, 95% CI 1.79-20.57, p=0.004; HR=5.40, 95% CI 1.76-16.57, p=0.003; HR=6.08, 95% CI 2.56-14.44, p<0.001 and HR= 1.02, 95% CI 1.01-1.03, P=0.002 respectively). Liver metastases and WBC before ICI were associated with increased death risk (HR=11.95, 95%CI 3.22-44.34, p<0.001; HR=1.0001, 95% CI 1.00001-1.00002, p=0.036 respectively) while ICI response was associated with decreased death (HR=0.22, 95%CI 0.08-0.62, p=0.004). Chemotherapy responders were associated with better ICI treatment response (OR=6.52, 95%CI 1.45-29.24, p=0.014) while lymph node metastases and poor ECOG was associated with poor ICI response (OR=0.31, 95%CI 0.10-0.94, p=0.038; OR=0.32, 95%CI 0.11-0.95, p=0.040). Conclusions: Our data showed predictive role of rst-line chemotherapy response to ICIs treatment ecacy in aUC patients as well as other prognostic factors, such as ECOG status, serum white blood cell count or NLR and liver metastases.


Introduction
For decades, chemotherapy becomes the standard of treatment for advanced urothelial carcinoma (aUC).
Recent progress of immune checkpoint inhibitors (ICI) in metastatic UC opened a new page in this eld. Five programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) inhibitors, pembrolizumab, nivolumab, atezolizumab, durvalumab and avelumab showed bene ts on overall survival among post-chemo metastatic UC patients and received accelerated approval by the US Food and Drug Administration (FDA) in 2016. [1][2][3][4][5] However, recent evidence of phase 3 trials, DANUBE and IMvigor 211 did not reach the primary end point; thus durvalumab and atezolizumab were voluntarily withdrawn the indications in chemotherapy pre-treated bladder cancer. 3,6 In addition, results of the front line setting using ICI combination with chemotherapy in phase 3 IMvigor 130 and Keynote 361 did not show overall survival bene ts which lead to a treatment dilemma in advanced UC. 7,8 By far, the rst line treatment of metastatic UC with ICI is still controversy. Herein, we evaluated metastatic UC patients underwent ICI treatment and looked for the associations between clinical characteristics and outcomes.

Patients
This retrospective study was conducted through chart review. All methods were carried out in accordance with relevant guidelines and regulation and were approved by the institute review board of Taichung Veterans General Hospital, number CE19386B. The informed consents of all patients were waived by the institute review board of Taichung Veterans General Hospital as well. Metastatic UC patients who received atezolizumab or pembrolizumab with measurable radiographic outcomes between January 2015 and October 2020 were included.

Study assessment
The study end points were progression free survival after ICI treatment, overall survival after treatment start of metastatic diseases and ICI treatment response. Baseline patient characteristics including continuous variables, age, chemotherapy and ICI treatment cycles and duration, blood sample analysis before ICI, such as white blood cell (WBC) count, hemoglobin, neutrophil/lymphocyte ratio (NLR), platelets, lactate dehydrogenase (LDH) and albumin were recorded. The timing of blood samples collected were two weeks before ICI given. Other categorical parameters such as gender, primary tumor site, smoking, diabetes mellitus, chronic kidney disease (CKD), end stage renal disease (ESRD), metastatic sites, Eastern Cooperative Oncology Group (ECOG) status, survival status, treatment model, ICI response, chemotherapy duration, and ICI duration were recorded as well. CKD was de ned as estimated glomerular ltration rate less than 60 mL/minutes but not exceed ESRD. ESRD was de ned as patients who received regular dialysis therapy. Metastatic sites were recorded according to radiographic ndings by each sites among each case. Chemotherapy response and ICI response were recorded according to the Response Evaluation Criteria in Solid Tumor (RECIST) 1.1. The periods of radiographic evaluation were depended on the clinical demands between 4 weeks and 6 months among each cases. However, in the ICI and chemotherapy combination treatment patients, it is di cult to separate the treatment effect between both. Therefore, the treatment effect would be recorded both for chemotherapy, as well as for ICI. The chemotherapy duration or ICI duration were de ned as the period between the date of starting treatment and the radiographic progression date or the last dose date.

Statistical analysis
The differences between continuous values were analyzed by Mann-Whitney U and Fisher's exact test t test for continuous variables. Chi-square test was used for categorical variables. The progression free survival (PFS) and overall survival (OS) curves were plotted by the Kaplan-Meier method. Univariate and multivariate Cox hazard proportional regression was used to estimate the hazard ratio (HR) and 95% con dence interval (CI) for association between variables and PFS, OS and ICI treatment response. The ICI treatment response was de ned as complete response or partial response. All the statistical analyses were performed using SAS software version 9.2 (SAS Institute, Inc., Cary, NC, USA).

Discussion
Our study demonstrated a prognostic and predictive value of rst-line chemotherapy response to clinical outcomes in aUC patients which corresponded to the ndings in JAVELIN bladder 100. 9 No rst-line chemotherapy response or no chemotherapy were associated with poor PFS (HR = 5.70, p = 0.001, and HR = 6.08, p = 0.004 respectively). Despite of PFS, we also found chemotherapy response CR/PR/SD can predict the ICI treatment response (OR = 6.52, p = 0.014). This phenomenon corresponded to the rationale that chemotherapy induction in UC can deplete immunosuppressant cells, increasing T-cell in ltration into tumors, increasing antigen presentation and increasing PD-L1 expression. 10,11 Although we can't nd the association between chemotherapy response and OS, ICI treatment responders showed a 78% risk reduction in death and implicated the importance of the ICI response. In addition, without external validation of our database, the estimated PFS and OS in our study (10.94 and 28.44 months respectively) showed a comparative outcome with the JAVELIN study (3.7 and 21.4 months respectively). 9 We suggested the comparable clinical outcome in our study was the result of large proportion lymph node metastatic only (41.89%, 31/74) and high cisplatin utility rate (83.87%, 52/62) which also lead to a chemotherapy response rate 46.77% (29/62). The baseline demographics in our series showed a unique UC characteristic in Taiwan. Upper tract UC accounted for the largest proportion (54%, 40/74) and female patients were predominant among this part which lead to an increase of the female gender percentage (37.84%). 12,13 These characteristics were different from other reported series while urinary bladder UC and male gender were extremely larger.
In the chemotherapy era, Bajorin et al. determined Karnofsky performance status less than 80 and visceral metastases were two independent factors for survival; Bellmunt et al. identi ed ECOG status more than 0, hemoglobin level less than 10, and presence of liver metastases as poor prognostic factors to OS. 14,15 In ICI era, Khaki et al. reported a database analysis on prognostic model of rst-line ICI therapy and found ECOG ≧ 2, albumin < 3.5 g/dL, NLR > 5 and liver metastasis were associated with worse OS. 16 Ruiz-Bañobre et al. declared another prognostic model using ECOG, liver metastases, peritoneal metastases, albumin level and proton pump inhibitor use in a mixed rst-line and second-line ICI treatment setting. 17  were ver prognostic factors for overall survival. 18 Our data showed similar clinical biomarkers such as liver metastasis, ECOG status 1 or 2, and high NLR which were associated with higher risk of disease progression as well as liver metastasis, poor ICI response and WBC before ICI to increased death risk. Despite the performance status related clinical markers such as ECOG, hemoglobin level and albumin were considered on the OS because of the short survival nature in metastatic UC, Yu et al. revealed the pathophysiology of liver metastases in patients and preclinical models. 19 They found that liver metastases diminished peripheral T cells as well as the diversity and function which may cause increased NLR and reduce the response of ICI treatment. Interestingly, we also found lymph node metastases was associated with poor ICI response. The true reason may not be clari ed because of lacking other histology evidence. Currently, PD-L1 stain and new generation sequencing for the genomic pro ling are considered as predictive biomarkers for ICI treatment and were approved by USFDA for speci c indications. 20-22 However, genomic exams and clinical outcomes varied from a trial to another as well as the high costs of examinations. Therefore, clinical parameters, such as our results, can provide an alternative aspect on the predictive role using chemotherapy response as an indicator of ICI treatment effect.
Limitations of this study include small patient population, the retrospective nature, lack of external validation, and confounding of chemotherapy response and ICI response in the rst-line combination group. Thirty eight patients (51.35%, 38/74) received combination chemotherapy and ICI as rst-line therapy; however, instead of clarifying the individual drug response, we can only record the combination results as the surrogate. In addition, we did not obtain tissue PD-LI data and can't provide the In conclusion, our real world experience revealed the rst-line chemotherapy response as well as clinical factors including ECOG status, liver metastases, NLR, WBC before ICI could act as prognostic or predictive markers to the ICI related clinical outcomes. Utility of these clinical biomarkers can help in regimen decision and avoid fruitless treatments.