Immunotherapy for urothelial cancer: from the diagnostic pathologist's point of view

[Practical aspects of PD-L1 assessment in the treatment of urothelial carcinoma: Consensus of the uropathology group of the SEAP]

The recent addition of novel immunotherapy drugs for the treatment of urothelial carcinoma makes it necessary the establishment of criteria to harmonize the immunohistochemical assessment of PD-L1, both as a prognostic factor and for the selection of patients to be treated. In this scenario, a group of uropathologists from the Spanish Society of Pathological Anatomy, together with a medical oncologist as an external collaborator subspecialized in uro-oncology, have prepared this document of recommendations based on the available evidence. During PD-L1 assessment it is especially relevant the selection of the sample, its processing, the immunohistochemical platform and antibody used, and the algorithm applied in the interpretation of results. All these aspects must be indicated in the results report, which should be easily interpretable in a context of rapid evolution of immunological therapies.

PD-L1 immunoexpression and molecular characterization of histological subtypes in urothelial carcinoma

INTRODUCTION

Urothelial carcinoma (UC) has histological subtypes whose phenotype reflects their molecular diversity, behavior and response to conventional therapy. Immune checkpoint inhibitors (ICIs) have improved the management of UC by evaluation of PD-L1. In the case of PD-L1 22C3, the initiation of ICI is considered from a combined positive score (CPS) greater than 10. However, UC subtypes with absent PD-L1 22C3 expression in cases with CPS>10 may not respond to these treatments. This study aims to establish a correlation between the PD-L1 immunoexpression and molecular alterations in divergent differentiation and histological subtypes of UC (UC-s).

MATERIAL AND METHODS

Twenty-six samples of UC were detected from a total of 24 patients. Two pathologists performed separately an assessment of UC-s on hematoxylin-eosin as well as PD-L1 expression. Molecular study of each case was performed by next generation sequencing (NGS). A descriptive analysis of the variables included was conducted.

RESULTS

Nine cases (34.61%) showed a CPS>10, some with negative PD-L1 immunoexpression in aggressive UC-s. The molecular study revealed alterations in genes belonging to the p53/cell cycle control, RAS, and DNA repair pathways, among others. None of the alterations were exclusive to any histological subtype.

DISCUSSION

Special attention should be paid to CPS>10 cases that include histological subtypes of UC with divergent expression for PD-L1 as they may not respond to treatment with ICI. We recommend examining the proportion and PD-L1 status of each subtype, especially if it has aggressive behavior.

Atlas of PD-L1 for Pathologists: Indications, Scores, Diagnostic Platforms and Reporting Systems

Background. Innovative drugs targeting the PD1/PD-L1 axis have opened promising scenarios in modern cancer therapy. Plenty of assays and scoring systems have been developed for the evaluation of PD-L1 immunohistochemical expression, so far considered the most reliable therapeutic predictive marker. Methods. By gathering the opinion of acknowledged experts in dedicated fields of pathology, we sought to update the currently available evidence on PD-L1 assessment in various types of tumors. Results. Robust data were progressively collected for several anatomic districts and leading international agencies to approve specific protocols: among these, TPS with 22C3, SP142 and SP263 clones in lung cancer; IC with SP142 antibody in breast, lung and urothelial tumors; and CPS with 22C3/SP263 assays in head and neck and urothelial carcinomas. On the other hand, for other malignancies, such as gastroenteric neoplasms, immunotherapy has been only recently introduced, often for particular histotypes, so specific guidelines are still lacking. Conclusions. PD-L1 immunohistochemical scoring is currently the basis for allowing many cancer patients to receive properly targeted therapies. While protocols supported by proven data are already available for many tumors, dedicated studies and clinical trials focusing on harmonization of the topic in other still only partially explored fields are surely yet advisable.

Programmed death ligand-1 (PD-L1) immunohistochemical assessment using the QR1 clone in muscle-invasive urothelial carcinomas: a comparison with reference clones 22C3 and SP263

Programmed death ligand-1 (PD-L1) immunohistochemical (IHC) status is used to predict which patients with metastatic urothelial carcinoma (UC) will respond to immunotherapy. We aimed to compare QR1(Quartett), 22C3 (Dako), and SP263 (Ventana) detection of PD-L1 expression in muscle-invasive UCs and determine the best scoring algorithm for assessment of PD-L1 expression when using the QR1 clone. Our study included 69 UCs. For SP263 and 22C3, PD-L1-positive tumor cell (TC) and/or immune cell (IC) percentages (TC%/IC%) and the Combined Positive Score (CPS) were assessed, respectively (positivity cut-offs of ≥ 25% and ≥ 10). For QR1, both interpretation systems were evaluated. The concordances between assays were calculated. PD-L1 IHC staining characteristics were comparable between QR1, 22C3, and SP263 in both conventional and variant histology UCs. We demonstrated strong or very strong correlations between clones; the strongest correlation for TCs was between QR1 and SP263 (r = 0.92; p = 0.001) and for ICs was between QR1 and 22C3 (r = 0.85; p = 0.001). Our comparative analysis of the scoring algorithms revealed very good concordances among the three assays (range 0.791-0.878); the highest concordance was between QR1 and SP263 when CPS was used as the scoring algorithm for QR1 (0.878; p < 0.001). Our study is the first to demonstrate that the QR1 clone can be used to evaluate PD-L1 status in UCs, with a very good agreement rate with the reference clones. QR1 appeared to be more similar to the SP263 clone. With regard to the scoring algorithm, when evaluating PD-L1 expression using QR1 clone, CPS performed better compared with the TC%/IC% score.

Narrative review: update on immunotherapy and pathological features in patients with bladder cancer

Over the last few years efficacy of immunotherapy using immune checkpoint inhibitors (ICI) has been investigated in patients with bladder cancer (BC) at all stages. The present article aims to assess new therapeutic options with emerging agents in BC patients, shedding light on ICI-based treatments encompassing all disease stages, from non-muscle invasive (NMIBC) to muscle-invasive (MIBC) BC, concluding with metastatic MIBC. In bacillus Calmette-Guerin (BCG) unresponsive patients with carcinoma in situ, pembrolizumab has been recently approved. In the neoadjuvant setting, results from two clinical trials seem to identify pathological and genomic features of highly responsive tumors. Squamous cells and lymphoepithelioma/like histotypes, programmed cell-death ligand 1 (PD-L1) expression and high levels of activate T cells have been associated with higher response rate. In the metastatic setting, only 30% of patient may respond to ICI. A panel of biomarkers for patient selection is an actual need since the correlation between response and PD-L1 expression seem inconsistent across clinical trials, with some exceptions. Molecular characterization of BC, tumor mutation burden and immune-gene expression profiling might introduce new molecular biomarkers, hopefully transferable into the clinical-pathological practice.

A narrative review of individualized treatments of genitourinary tumors: is the future brighter with molecular evaluations?

Few molecular prognostic and predictive biomarkers have been identified so far in genitourinary tumors. We started from a literature search to explore the status of the art of molecular pathology tests as diagnostic, prognostic, predictive biomarkers in genitourinary cancers. Next generation sequencing approaches now provide mind-changing information in the fields of kidney cancer diagnosis, predictive oncology of urothelial cancer, understanding the causes of testicular and penile cancer, and the comprehension of the drivers of prostate cancer progression beyond androgen regulation. The classification of kidney cancer will be based soon on molecular changes. The causes of non-HPV related penile cancer are largely unknown. The emerging high incidence of testicular cancer could be explained only on the basis of molecular changes. The response to novel therapeutic agents in prostatic and urothelial cancer will require thorough molecular tumor characterization. The hereditary risk of patients with early onset prostate cancer and their potential treatment with targeted therapy requires germline and somatic genetic assays. The implementation of effective biomarkers for the response to immune check-point inhibitors in genitourinary cancer is based on the assessment of inflammatory expression profiles and the tumor mutational burden. This review deals with the current tests and provides a tentative foresee of the future molecular biomarkers of genitourinary cancer.

Stage T1 bladder cancer: diagnostic criteria and pitfalls

Accurate pathological staging is crucial for patient management. Patients with T1 bladder cancer are at risk of recurrence, progression, and death of cancer. Recognition of early invasion (stage T1 disease) in urothelial carcinoma remains one of the most challenging areas in urological surgical pathology practice. A logical roadmap to T1 diagnosis would include careful evaluation of histological grade, stromal epithelial interface, characteristics of the invading epithelium, and the stroma associated responses. Tangential sectioning, crush and cautery artifacts, and associated inflammatory infiltrate are commonly encountered problems and the source of pitfalls. In this review, we outline diagnostic criteria, common pitfalls, and different histological patterns of invasion into the lamina propria. Current recommendations on reporting of biopsy and transurethral resection specimens, molecular biomarkers, clinical implications of T1 cancer diagnosis and recent developments on the T1 substaging are also discussed. Most T1 bladder cancer patients will benefit from conservative management after restaging transurethral resection of bladder and bacillus Calmette-Guérin maintenance. Patients with high risk features, such as concurrent urothelial carcinoma in situ, increased depth of invasion, lymphovascular invasion, and variant histology among others, should be considered for early cystectomy.