Absence of GNAS and BRAF mutations but presence of KRAS mutation in urachal adenocarcinoma

Progress and prospects of targeted therapy and immunotherapy for urachal carcinoma

Introduction: Urachal carcinoma (UrC) is a rare and aggressive disease. Systematic chemotherapy shows limited efficacy in patients with advanced disease, while targeted therapy and immunotherapy may provide a reasonable alternative for specific populations. The molecular pattern of colorectal cancer (CRC) have recently been identified; this understanding has significantly influenced the clinical management of CRC in terms of molecular-targeted therapy. Although some genetic alterations have been associated with UrC, there is still no systematic overview of the molecular profile of this rare malignancy. Methods: In this review, we comprehensively discuss the molecular profile of UrC and further identify potential targets for the personalized treatment of UrC as well as immune checkpoint inhibitors that represent underlying biomarkers. A systematic literature search was carried out by searching the PubMed, EMBASE, and Web of Science databases to identify all literature related to targeted therapy and immunotherapy in urachal carcinoma from inception to February 2023. Results: A total of 28 articles were eligible, and most studies included were case report sand retrospective case series. Furthermore, 420 cases of UrC were identified to analyze the association between mutations and UrC. The most commonly mutated gene in UrC was TP53 with the prevalence of 70%, followed by KRAS mutations in 28.3%, MYC mutations in 20.3%, SMAD4 mutations in 18.2% and GNAS mutations in 18%, amongst other genes. Discussion: The molecular patterns of UrC and CRC are similar yet distinct. Notably, targeted therapy, especially EGFR-targeting therapy, might provide curative efficacy for patients with UrC by applying specific molecular markers. Additional potential biomarkers for the immunotherapy of UrC are mismatch repair (MMR) status and PD-L1 expression profile. In addition, combined regimens featuring targeted agents and immune checkpoint blockers might increase antitumor activity and exert better efficacy in UrC patients with specific mutational burden.

Distinct Gene Mutations Are Associated With Clinicopathologic Features in Urachal Carcinoma

OBJECTIVES

To investigate the gene mutational profile of urachal carcinoma in correlation with its clinicopathologic features.

METHODS

We analyzed genetic mutations in 30 cases of urachal carcinoma by next-generation sequencing (NGS) test. Histologic slides and clinical data were reviewed.

RESULTS

The patients included 21 men and 9 women, with a mean age of 53 years (range, 24-75 years). The urachal carcinomas included mucinous (11), enteric (10), signet ring cell (8), and high-grade neuroendocrine (1) subtypes. Targeted NGS analysis demonstrated genetic mutations in all the urachal tumors (mean, 2; range, 1-4). TP53 was the most mutated gene (25), followed by KRAS (9) and GNAS (8) genes. TP53 mutations were more common in the signet ring cell subtype (7/8), and GNAS mutations were present only in the mucinous (5/11) and signet ring cell subtypes (3/8) but not in the enteric subtype (0/10). KRAS mutations were significantly associated with cancer stage IV (P = .02) and younger patient age (P = .046). Furthermore, the presence of KRAS mutations in urachal carcinoma portended a poorer overall survival (P = .006).

CONCLUSIONS

Urachal carcinoma demonstrates frequent gene mutations that are associated with distinct clinicopathologic features. Gene mutation may underlie the development and progression of this aggressive disease.

Prevalence of APC and PTEN Alterations in Urachal Cancer

Urachal carcinoma (UrC) is a rare tumor with remarkable histological and molecular similarities to colorectal cancer (CRC). Adenomatous polyposis coli (APC) is the most frequently affected gene in CRC, but the prevalence and significance of its alterations in UrC is poorly understood. In addition, loss of phosphatase and tensin homologue (PTEN) was shown to be associated with therapy resistance in CRC. Our primary aim was to assess specific genetic alterations including APC and PTEN in a large series of UrC samples in order to identify clinically significant genomic alterations. We analyzed a total of 40 UrC cases. Targeted 5-gene (APC, PTEN, DICER1, PRKAR1A, TSHR, WRN) panel sequencing was performed on the Illumina MiSeq platform (n = 34). In addition, ß-catenin (n = 38) and PTEN (n = 30) expressions were assessed by immunohistochemistry. APC and PTEN genes were affected in 15% (5/34) and 6% (2/34) of cases. Two of five APC alterations (p.Y1075*, p.K1199*) were truncating pathogenic mutations. One of the two PTEN variants was a pathogenic frameshift insertion (p.C211fs). In 29% (11/38) of samples, at least some weak nuclear ß-catenin immunostaining was detected and PTEN loss was observed in 20% (6/30) of samples. The low prevalence of APC mutations in UrC represents a characteristic difference to CRC. Based on APC and ß-catenin results, the Wnt pathway seems to be rarely affected in UrC. Considering the formerly described involvement of PTEN protein loss in anti-EGFR therapy-resistance its immunohistochemical testing may have therapeutic relevance.

Urachal Cancer in Germany and the USA: An RKI/SEER Population-Based Comparison Study

INTRODUCTION

Urachal cancer (UrC) is a rare but aggressive cancer. Due to its low incidence, structured epidemiological data have only rarely been reported. To date, no valid data on UrC are available for the German population.

METHODS

Data on incidence and relative 5-year survival of urachal lesions (ICD-10: C67.7) were collected from all population-based cancer registries in Germany, provided by the Robert Koch-Institut (RKI). Data were anonymized and included age, sex, and general histology (ICD-O-3). For comparison, a similar inquiry of the "Surveillance, Epidemiology, and End Results program" (SEER-18) database for the USA was conducted.

RESULTS

From 2011 to 2015, a total of 154 and 152 cases of UrC were reported for Germany (RKI) and the USA (SEER-18 area), respectively. Age-standardized incidence was 0.32/1,000,000 age-standardized cases/year in both cohorts, and elderly persons were more often affected. The major histological type was adenocarcinoma (64.9 and 81.6%). Relative 5-year survival was 54.8% (CI: 45.0-64.6) in Germany (RKI) and 64.4% (54.1-72.1) in the USA (SEER-18 cohort). Discusssion/Conclusion: The collected data demonstrate low incidence rates and similar epidemiological and clinicopathological characteristics of UrC for both registries. This is the first report of structured epidemiological data for UrC for the German population.

Urachal cancer-current concepts of a rare cancer

Urachal cancer is a rare but aggressive disease. In addition to the non-glandular tumors, non-cystic urachal adenocarcinomas are nowadays distinguished from the primary cystic variant. (Immunohistochemical) markers are only of minor differential diagnostic value and, therefore, the diagnosis is primarily established in a multidisciplinary approach. The non-cystic variant accounts for the majority of cases (83%), is more common in men (63%), shows a median age at diagnosis of 51 years and has a 5-year survival rate of about 50%. In organ-confined disease, usually a partial cystectomy of the tumor in the bladder dome, including the median umbilical ligament and umbilicus, is performed. In advanced stages, systemic therapy is needed while 5‑fuorouracil (5-FU) containing regimes have been shown to be more effective. Due to the rarity of the tumor, targeted therapy approaches based on a biological rationale are becoming increasingly relevant. As molecular data are still sparse, we compiled and analyzed the largest urachal cancer cohort to date. In 31% of the cases, MAPK-/PI3K signaling pathway alterations were detected (especially in K-/NRAS) with implications for anti-EGFR therapy approaches. Further potentially therapeutic alterations were detected in FGFR1, MET, PDGFRA, and erbB2/HER2. Additionally, PD-L1 tumor cell expression (clone: 22C3) was demonstrated in 16% of cases, therefore making anti-PD-1/PD-L1 immuno-oncological approaches worth considering despite the absence of mismatch repair deficiency (MMR-d) and/or high microsatellite instability (MSI-h). Finally, urachal adenocarcinomas seem to be a distinct entity on the molecular level with closer resemblance to colorectal adenocarcinomas than to urothelial carcinomas.

[Urachal cancer - current concepts of a rare cancer (German version)]

Urachal cancer is a rare but aggressive disease. In addition to the non-glandular tumors, non-cystic urachal adenocarcinomas are nowadays distinguished from the primary cystic variant. (Immunohistochemical) markers are only of minor differential diagnostic value and, therefore, the diagnosis is primarily established in a multidisciplinary approach. The non-cystic variant accounts for the majority of cases (83%), is more common in men (63%), shows a median age at diagnosis of 51 years and has a 5-year survival rate of about 50%. In organ-confined disease, usually a partial cystectomy of the tumor in the bladder dome, including the median umbilical ligament and umbilicus, is performed. In advanced stages, systemic therapy is needed while 5‑fuorouracil (5-FU) containing regimes have been shown to be more effective. Due to the rarity of the tumor, targeted therapy approaches based on a biological rationale are becoming increasingly relevant. As molecular data are still sparse, we compiled and analyzed the largest urachal cancer cohort to date. In 31% of the cases, MAPK-/PI3K signaling pathway alterations were detected (especially in K-/NRAS) with implications for anti-EGFR therapy approaches. Further potentially therapeutic alterations were detected in FGFR1, MET, PDGFRA, and erbB2/HER2. Additionally, PD-L1 tumor cell expression (clone: 22C3) was demonstrated in 16% of cases, therefore making anti-PD-1/PD-L1 immuno-oncological approaches worth considering despite the absence of mismatch repair deficiency (MMR-d) and/or high microsatellite instability (MSI-h). Finally, urachal adenocarcinomas seem to be a distinct entity on the molecular level with closer resemblance to colorectal adenocarcinomas than to urothelial carcinomas.