Comprehensive Assessment of Immuno-oncology Biomarkers in Adenocarcinoma, Urothelial Carcinoma, and Squamous-cell Carcinoma of the Bladder.

BACKGROUND: In patients with rare histologies of bladder cancer, including adenocarcinoma of the bladder (ACB) and squamous-cell carcinoma (SCC), there are limited standard therapy options, defining an unmet medical need. OBJECTIVE: In this comparative comprehensive genomic profiling (CGP) study, genomic alterations (GAs), and immuno-oncology (IO) biomarkers have been analyzed. DESIGN, SETTING, AND PARTICIPANTS: Within the Foundation Medicine database, 143 cases with centrally reviewed pure ACB, 2142 with pure urothelial carcinoma (UC), and 83 with pure SCC were subjected to CGP. All patients developed advanced disease following a primary diagnosis of bladder cancer. INTERVENTION: CGP using a hybrid capture-based assay and immunohistochemistry (IHC). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Tumor mutational burden (TMB) was determined on 1.1 Mbp of sequenced DNA, and microsatellite instability (MSI) was determined on 114 loci. Programmed cell-death ligand-1 (PD-L1) expression was determined by IHC (Ventana SP-142 assay), with >1% tumor cells (TCs) or tumor-infiltrating lymphocytes (TILs) scoring positive. RESULTS AND LIMITATIONS: Pure ACB patients were younger and more often female than pure UC and pure SCC patients. UC and SCC had a significantly higher median TMB than ACB (p < 0.001). Rare CD274 (PD-L1) amplification cases were more frequently seen in SCC than in UC (5% vs 1%), and were not seen in ACB. MSI high status was very uncommon in all tumor types (0-1%). The frequencies of PD-L1 expression in both TCs and TILs was higher in UC and SCC (both 30%) than in ACB (18%). The results are limited by their retrospective nature and lack of clinical data annotation. CONCLUSIONS: Deep sequencing revealed significant differences in IO biomarkers among the three major subtypes of bladder carcinomas. UC and SCC revealed higher frequencies of PD-L1 expression and higher TMB than ACB, and SCC has the highest frequency of CD274 amplification. The presence of pure SCC features should not disqualify patients for inclusion in IO trials. PATIENT SUMMARY: Tumor samples from patients diagnosed with advanced pure adenocarcinoma of the bladder (ACB) or pure squamous-cell carcinoma (SCC) have been analyzed in terms of frequency of putative immunotherapy biomarkers. The results indicated that pure SCC of the bladder was characterized by genomic features that portend similar response possibilities to immunotherapy compared with the classical pure urothelial carcinoma. Conversely, for pure ACB there might be different therapeutic opportunities, such as targeted therapies against peculiar genomic alterations in selected patients.

Multiparametric Magnetic Resonance Imaging as a Noninvasive Assessment of Tumor Response to Neoadjuvant Pembrolizumab in Muscle-invasive Bladder Cancer: Preliminary Findings from the PURE-01 Study.

BACKGROUND: In the PURE-01 study, pembrolizumab was given preoperatively before radical cystectomy in clinical T2-4aN0M0 patients. An accurate clinical response assessment may be useful for developing new perioperative strategies in these patients. OBJECTIVE: To evaluate the association between bladder multiparametric magnetic resonance imaging (mpMRI) findings after pembrolizumab and the pathological complete response (CR; pT0). DESIGN, SETTING, AND PARTICIPANTS: Patients were staged using bladder mpMRI whereby radiologists were asked to characterize the following parameters: residual disease at T1- and T2-weighted images (step 1: yes/no), presence of hyperintense spots within the bladder wall on diffusion-weighted imaging (step 2: yes/no), and presence of pathological contrast enhancement (step 3: yes/no), before and after three cycles of pembrolizumab. Examinations were internally assessed by two senior radiologists and externally evaluated by a third senior radiologist. INTERVENTION: To evaluate bladder tumor response after neoadjuvant pembrolizumab, mpMRI was used. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary objective was to predict the pT0 after neoadjuvant pembrolizumab by relying on the mpMRI findings. Cohen's kappa statistics was used to assess interobserver variability. Univariable analyses for pT0 were performed including internal and external post-therapy mpMRI steps. RESULTS AND LIMITATIONS: From February 2017 to October 2018, 82 patients (164 total mpMRI assessments) were analyzed. The agreement between the internal and external mpMRI assessments after therapy was acceptable (κ values ranging from 0.5 to 0.76). Each mpMRI step was significantly associated with pT0 in both internal and external assessments. In patients with CR/no evidence of residual disease (NED) in all internally evaluated mpMRI steps (N = 37), the pT0 was seen in 23 (62%), compared with 19 of 26 externally evaluated NED patients (73%). CONCLUSIONS: In post-pembrolizumab muscle-invasive bladder cancer, mpMRI sequence assessment had acceptable interobserver variability and represented the basis for the proposal of a radiological CR/NED status definition predicting the pT0 response to pembrolizumab. After validation of these findings with external datasets, we propose this tool for developing bladder-sparing immunotherapy maintenance therapies. PATIENT SUMMARY: Assessment of the extent of disease in patients with muscle-invasive bladder cancer using conventional imaging yields serious limitations. In the PURE-01 study, we evaluated the potential of bladder multiparametric magnetic resonance imaging (MRI) to predict the pathological complete response to neoadjuvant pembrolizumab. After validation with larger datasets, the proposed stepwise assessment incorporating multiparametric MRI sequences will be used at our center to develop bladder-sparing approaches in future studies.

Beyond microsatellite testing: assessment of tumor mutational burden identifies subsets of colorectal cancer who may respond to immune checkpoint inhibition.

BACKGROUND: The clinical application of PD1/PD-L1 targeting checkpoint inhibitors in colorectal cancer (CRC) has largely focused on a subset of microsatellite instable (MSI-high) patients. However, the proposed genotype that sensitizes these patients to immunotherapy is not captured by MSI status alone. Estimation of tumor mutational burden (TMB) from comprehensive genomic profiling is validated against whole exome sequencing and linked to checkpoint response in metastatic melanoma, urothelial bladder cancer and non-small cell lung carcinoma. We sought to explore the subset of microsatellite stable (MSS) CRC patients with high TMB, and identify the specific genomic signatures associated with this phenotype. Furthermore, we explore the ability to quantify TMB as a potential predictive biomarker of PD1/PD-L1 therapy in CRC. METHODS: Formalin-fixed, paraffin embedded tissue sections from 6,004 cases of CRC were sequenced with a CLIA-approved CGP assay. MSI and TMB statuses were computationally determined using validated methods. The cutoff for TMB-high was defined according to the lower bound value that satisfied the 90% probability interval based on the TMB distribution across all MSI-High patients. RESULTS: MSS tumors were observed in 5,702 of 6,004 (95.0%) cases and MSI-H tumors were observed in 302 (5.0%) cases. All but one (99.7%) MSI-H cases were TMB-high (range, 6.3-746.9 mut/Mb) and 5,538 of 5,702 (97.0%) MSS cases were TMB-low (range, 0.0-10.8 mut/Mb). Consequently, 164 of 5,702 (2.9%) MSS cases were confirmed as TMB-high (range, 11.7-707.2 mut/Mb), representing an increase in the target population that may respond to checkpoint inhibitor therapy by 54% (466 vs. 302, respectively). Response to PD-1 inhibitor is demonstrated in MSS/TMB-high cases. CONCLUSIONS: Concurrent TMB assessment accurately classifies MSI tumors as TMB-high and simultaneously identifies nearly 3% or CRC as MSS/TMB-high. This subgroup may expand the population of CRC who may benefit from immune checkpoint inhibitor based therapeutic approaches.