Coexisting well-differentiated and anaplastic thyroid carcinoma in the same primary resection specimen: immunophenotypic and genetic comparison of the two components in a consecutive series of 13 cases and a review of the literature

Anaplastic carcinoma (AC) is a rare but highly aggressive form of thyroid cancer. It mostly arises on a background of pre-existing well-differentiated cancer (WDC); however, whether it evolves directly from a WDC or originates as a second independent neoplasm is still to be defined. To obtain further insights into these mechanisms, we performed morphological, immunohistochemical, and next-generation sequencing analyses to compare AC and its associated WDC in a subset of 13 surgically resected specimens. Histologically, most WDC were of aggressive subtypes. Papillary carcinomas (8 cases; 62%) were tall cell (4/8), columnar (1/8), classic with hobnail features (1/8), classic and follicular variant in the remaining 2 cases; Hürthle cell and follicular carcinomas were present in 5 (38%) and in 1 (8%) patient, respectively. One patient harbored both a PTC, follicular variant, and a Hürthle cell carcinoma. We did not find any correlation between a histotype of WDC and a specific anaplastic growth pattern. Immunohistochemically, ACs retained pankeratin/PAX8 expression but with significantly lower levels than WDCs, and they tended to lose TTF1 expression, as can be expected within a dedifferentiation process. In addition, AC showed a more frequent expression of p63 and/or SMA, a mutated pattern of p53, and an abnormal expression of p16. Genetic analysis showed that the number of mutations was higher in AC than in the associated WDC, confirming a role of the progressive accumulation of genetic damage in this transition. We observed that mutations found in the WDCs were consistently identified in the anaplastic counterparts, further supporting the hypothesis of a developmental link.

FGF-Receptors and PD-L1 in Anaplastic and Poorly Differentiated Thyroid Cancer: Evaluation of the Preclinical Rationale

BACKGROUND

Treatment options for poorly differentiated (PDTC) and anaplastic (ATC) thyroid carcinoma are unsatisfactory and prognosis is generally poor. Lenvatinib (LEN), a multi-tyrosine kinase inhibitor targeting fibroblast growth factor receptors (FGFR) 1-4 is approved for advanced radioiodine refractory thyroid carcinoma, but response to single agent is poor in ATC. Recent reports of combining LEN with PD-1 inhibitor pembrolizumab (PEM) are promising.

MATERIALS AND METHODS

Primary ATC (n=93) and PDTC (n=47) tissue samples diagnosed 1997-2019 at five German tertiary care centers were assessed for PD-L1 expression by immunohistochemistry using Tumor Proportion Score (TPS). FGFR 1-4 mRNA was quantified in 31 ATC and 14 PDTC with RNAscope in-situ hybridization. Normal thyroid tissue (NT) and papillary thyroid carcinoma (PTC) served as controls. Disease specific survival (DSS) was the primary outcome variable.

RESULTS

PD-L1 TPS≥50% was observed in 42% of ATC and 26% of PDTC specimens. Mean PD-L1 expression was significantly higher in ATC (TPS 30%) than in PDTC (5%; p<0.01) and NT (0%, p<0.001). 53% of PDTC samples had PD-L1 expression ≤5%. FGFR mRNA expression was generally low in all samples but combined FGFR1-4 expression was significantly higher in PDTC and ATC compared to NT (each p<0.001). No impact of PD-L1 and FGFR 1-4 expression was observed on DSS.

CONCLUSION

High tumoral expression of PD-L1 in a large proportion of ATCs and a subgroup of PDTCs provides a rationale for immune checkpoint inhibition. FGFR expression is low thyroid tumor cells. The clinically observed synergism of PEM with LEN may be caused by immune modulation.

E-cadherin/α-catenin deregulated co-expression in thyroid carcinoma based on tissue microarray digital image analysis

PURPOSE

Deregulation of cell-to-cell adhesion molecules is a common and also critical genetic event in epithelial malignancies leading to an increasing metastatic potential. Among them, e-cadherin and catenins--especially α and β--, act as oncogenes during the carcinogenetic process affecting specific signaling transduction pathways (i.e. Wnt/ b-catenin). Concerning thyroid carcinoma, decreased or loss of expression in these proteins seems to affect the biological behavior of the neoplasm increasing its aggressiveness. The aim of this study was to investigate the deregulation of e-cadherin/α-catenin complex in thyroid carcinomas.

METHODS

Thirty-five paraffin-embedded tissue samples including thyroid carcinomas (N=20) and also 15 cases of benign follicular nodules were cored at 1 mm diameter and transferred to a microarray block. Immunohistochemistry (IHC) was performed using anti-e-cadherin/α-catenin antibodies. Digital image analysis was also implemented for measuring the corresponding protein expression levels.

RESULTS

E-cadherin/α-catenin protein expression demonstrated a significant progressive decrease regarding benign and malignant lesions (p=0.001). Simultaneous e-cadherin/α-catenin reduced or loss of expression was observed in 10/20 (50%) cancer cases correlated to advanced stage (especially nodal metastasis) of the examined tumours (p=0.02). Concerning the histological type, combined loss of e-cadherin/α-catenin expression was predominantly associated with follicular and anaplastic histology (p=0.001). Interestingly, α-catenin protein expression pattern was significantly correlated with the grade of differentiation of the examined malignancies (p=0.01).

CONCLUSIONS

Progressive loss of e-cadherin mainly and also α-catenin expression is associated with an aggressive phenotype (low differentiation, increased metastatic activity/advanced stage) in thyroid carcinomas. Based on their aberrant protein expression, novel agents have been developed for restoring their normal function.