Noninvasive Papillary Basal-like Urothelial Carcinoma: A Subgroup of Urothelial Carcinomas With Immunohistochemical Features of Basal Urothelial Cells Associated With a High Rate of Recurrence and Progression

Are We Ready to Implement Molecular Subtyping of Bladder Cancer in Clinical Practice? Part 1: General Issues and Marker Expression

Bladder cancer (BC) is a heterogeneous disease with highly variable clinical and pathological features, and resulting in different outcomes. Such heterogeneity ensues from distinct pathogenetic mechanisms and may consistently affect treatment responses in single patients. Thus, over the last few years, several groups have developed molecular classification schemes for BC, mainly based on their mRNA expression profiles. A “consensus” classification has recently been proposed to combine the published systems, agreeing on a six-cluster scheme with distinct prognostic and predictive features. In order to implement molecular subtyping as a risk-stratification tool in routine practice, immunohistochemistry (IHC) has been explored as a readily accessible, relatively inexpensive, standardized surrogate method, achieving promising results in different clinical settings. The first part of this review deals with the steps resulting in the development of a molecular subtyping of BC, its prognostic and predictive implications, and the main features of immunohistochemical markers used as surrogates to stratify BC into pre-defined molecular clusters.

Fibroblast activation protein (FAP) expression in CK5/6 expressed (Basal subtype) & CK20 expressed (Luminal subtype) urothelial bladder carcinoma: an immunohistochemical study

Urinary bladder cancer incidence varies all over the world. Egypt displays high incidence rates. Molecular subtyping helps risk stratification and personalized treatment. Cancer-associated fibroblasts (CAFs) in the tumor microenvironment may provoke tumor-promotion or tumor suppression. Fibroblast activation protein (FAP) is a marker of CAFs, suggested to accelerate tumor progression in various cancers. In urothelial carcinoma, investigations regarding impact of FAP expression on prognosis are needed. This work aims to study impact of FAP expression in urothelial carcinoma and find its relation to CK 5/6 (basal) expressed and CK 20 (luminal) expressed immunohistochemical markers. This retrospective study included 70 urothelial carcinoma specimens. Immunohistochemistry was performed and results were analyzed. FAP was expressed in 67.1% of cases and showed significant association with advanced tumor stage, muscle invasion, mitoses in tumor cells and stratified groups; as 73.9% of FAP positive cases were of Ck5/6+/Ck20- (basal subtype). All studied parameters did not show significant association with patient's overall survival. In conclusion, FAP could have a role in modulating tumor microenvironment and promoting tumor invasion. FAP is correlated with basal subtype of urothelial carcinoma, which may be an indicator of tumor aggressiveness. FAP antagonists may be helpful in preventing tumor progression.

Cytokeratin 5 and cytokeratin 6 expressions are unconnected in normal and cancerous tissues and have separate diagnostic implications

Cytokeratins (CKs) 5 and 6 are functionally unrelated but often analyzed together using bispecific antibodies in diagnostic immunohistochemistry. To better understand the diagnostic utility of CK5 or CK6 alone, tissue microarrays with > 15,000 samples from 120 different tumor types as well as 608 samples of 76 different normal tissues were analyzed by immunohistochemistry. In normal tissues, both CKs occurred in the squamous epithelium; CK5 dominated in basal and CK6 in suprabasal layers. CK5 (not CK6) stained basal cells in various other organs. Within tumors, both CK5 and CK6 were seen in > 95% of squamous cell carcinomas, but other tumor entities showed different results: CK5 predominated in urothelial carcinoma and mesothelioma, but CK6 in adenocarcinomas. Joint analysis of both CK5 and CK6 obscured the discrimination of epithelioid mesothelioma (100% positive for CK5 alone and for CK5/6) from adenocarcinoma of the lung (12.8% positive for CK5 alone; 23.7% positive for CK5/6). CK5 and CK6 expressions were both linked to high grade, estrogen receptor, and progesterone receptor negativity in breast cancer (p < 0.0001 each), grade/stage progression in urothelial cancer (p < 0.0001), and RAS mutations in colorectal cancer (p < 0.01). Useful diagnostic properties which are commonly attributed to CK5/6 antibodies such as basal cell staining in the prostate, distinction of adenocarcinoma of the lung from squamous cell carcinoma and epithelioid mesothelioma, and identification of basal-type features in urothelial cancer are solely driven by CK5. At least for the purpose of distinguishing thoracic tumors, monospecific CK5 antibodies may be better suited than bispecific CK5/6 antibodies.

Immunohistochemistry of cytokeratin (CK) 5/6, CD44 and CK20 as prognostic biomarkers of non-muscle-invasive papillary upper tract urothelial carcinoma

AIMS

Immunohistochemical (IHC) staining for cytokeratin (CK) 5/6, CD44 and CK20 has been significantly associated with the prognosis of urinary bladder urothelial carcinoma, and probably reflects its molecular characteristics. We aimed to investigate the IHC-based subgroups and their prognostic effects on non-muscle-invasive papillary upper tract urothelial carcinoma (UTUC).

METHODS AND RESULTS

IHC staining for CK5/6, CK20 and CD44 was analysed in 211 patients with non-muscle-invasive papillary UTUC. Staining was classified as showing a negative, positive or normal pattern. We found that CK5/6-negative, CD44-negative and CK20-positive tumours were distinctly high-risk subgroups that were associated with high grade (CK5/6-negative, P < 0.001; CD44-negative, P < 0.001; CK20-positive, P = 0.017) and frequent intravesical recurrence (CK5/6-negative, P = 0.002). Using survival analysis with Kaplan-Meier and log-rank tests, we found that these IHC subgroups were correlated with poor progression-free (CK5/6-negative, P = 0.001; CD44-negative, P = 0.009; CK20-positive, P = 0.031) and cancer-specific (CK5/6-negative, P = 0.009) survival. Furthermore, CK5/6 negativity was an independent prognostic factor for shorter progression-free (P = 0.009) and cancer-specific (P = 0.045) survival. CK5/6 improved Harrell's C-indices for progression-free (0.68-0.77, P = 0.029) and cancer-specific (0.59-0.77, P < 0.001) survival. When markers were combined, luminal-like subtypes showed poor prognoses.

CONCLUSIONS

We demonstrated that IHC staining for CK5/6, CD44 and CK20 was significantly associated with the clinicopathological characteristics and prognoses of patients with non-muscle-invasive papillary UTUC. The IHC subgroups may be correlated with the molecular characteristics of non-muscle-invasive papillary UTUC.

Immunohistochemiocal subtyping using CK20 and CK5 can identify urothelial carcinomas of the upper urinary tract with a poor prognosis

PURPOSE

Genome-wide analyses revealed basal and luminal subtypes of urothelial carcinomas of the bladder. It is unknown if this subtyping can also be applied to upper tract urothelial carcinomas.

MATERIALS AND METHODS

Tumor samples from 222 patients with upper tract urothelial carcinomas who were treated with radical nephroureterectomy were analyzed for the expression of seven basal/luminal immunohistochemical markers (CK5, EGFR, CD44, CK20, p63, GATA3, FOXA1).

RESULTS

Hierarchical clustering revealed a basal-like subtype (enrichment of CK5, EGFR and CD44) in 23.9% and a luminal-like subtype (enrichment of CK20, GATA3, p63 and FOXA1) in 13.1% of the patients. In 60.8%, little to no markers were expressed, whereas markers of both subtypes were expressed in 2.2%. By using CK5 and CK20 as surrogate markers for the basal and luminal subtypes, we defined four subtypes of upper tract urothelial carcinomas: (i) exclusively CK20 positive and CK5 negative (CK20+/CK5-), (ii) exclusively CK5 positive and CK20 negative (CK20-/ CK5+), (iii) both markers positive (CK20+/CK5+) and (iv) both markers negative (CK20-/CK5-). A receiver-operator analysis provided the optimal cut-off values for this discrimination. An immunoreactive score >1 for CK5 and >6 for CK20 were defined as positive. In multivariate Cox's regression analysis, the CK20+/CK5- subtype was an independent negative prognostic marker with a 3.83-fold increased risk of cancer-specific death (p = 0.02) compared to the other three subtypes.

CONCLUSIONS

Immunohistochemical subgrouping of upper tract urothelial carcinomas by analyzing CK5 and CK20 expression can be performed in a routine setting and can identify tumors with a significantly worse cancer-specific survival prognosis.