Biomarkers of immunotherapy in urothelial and renal cell carcinoma: PD-L1, tumor mutational burden, and beyond

Immune checkpoint inhibitors targeting the PD-1 pathway have greatly changed clinical management of metastatic urothelial carcinoma and metastatic renal cell carcinoma. However, response rates are low, and biomarkers are needed to predict for treatment response. Immunohistochemical quantification of PD-L1 was developed as a promising biomarker in early clinical trials, but many shortcomings of the four different assays (different antibodies, disparate cellular populations, and different thresholds of positivity) have limited its clinical utility. Further limitations include the use of archival specimens to measure this dynamic biomarker. Indeed, until PD-L1 testing is standardized and can consistently predict treatment outcome, the currently available PD-L1 assays are not clinically useful in urothelial and renal cell carcinoma. Other more promising biomarkers include tumor mutational burden, profiles of tumor infiltrating lymphocytes, molecular subtypes, and PD-L2. Potentially, a composite biomarker may be best but will need prospective testing to validate such a biomarker

Copy number gains at chr3p25 and chr11p11 are associated with lymph node involvement and survival in muscle-invasive bladder tumors

<div><p>Patients with muscle-invasive bladder cancer (MIBC) have poorer prognoses if cancer has metastasized to the lymph nodes. Genomic markers of lymph node involvement (LNI) would be useful for treatment planning, especially if measured at the biopsy stage, but large-scale studies of tumor tissue at any stage are needed to discover robust markers of LNI. We performed a genome-wide query of copy number alterations (CNA) in 237 MIBC surgical tumor specimens from patients in The Cancer Genome Atlas who had radical cystectomy and lymphadenectomy without neoadjuvant treatment. Pathology reports were independently reviewed to confirm LNI, and copy number data was analyzed to confirm gene-level gains and losses while adjusting for tumor purity and ploidy. Using logistic regression and elastic net models, we identified the CNA most significantly associated with LNI. Multivariable logistic regression was used to describe these CNA associations while adjusting for clinical variables. Kaplan-Meier and Cox regression were used to describe their association with overall survival. Gains in 26 genes were identified as having strong associations with LNI. After adjusting for age, gender, race, pathological tumor stage, histology, and number of nodes examined, gains in 22 genes on chr3p25 or chr11p11 remained significantly associated with LNI (p<0.01) and improved model discrimination over clinical variables alone (p = 0.04). They were also associated with shorter overall survival (adjusted p = 0.02). These results suggest that a simple genomic test for gains in chr3p25 and chr11p11 could inform adjuvant treatment or clinical trial decisions if validated in external cohorts. Additional studies will also be needed to determine if these CNA are detectible in biopsy tissue and can inform clinical decisions at the preoperative stage.</p></div

Kaplan-Meier survival curves for 24-month survival.

<p>A. By lymph node involvement, B. By chr3p25, chr11p11 gain. C. By lymph node involvement and chr3p25, chr11p11 gain.</p

Patient and clinical characteristics by lymph node involvement.

<p>Patient and clinical characteristics by lymph node involvement.</p

Logistic regression results describing gene set association with lymph node involvement, with and without adjusting for clinical variables.

<p>Logistic regression results describing gene set association with lymph node involvement, with and without adjusting for clinical variables.</p