PD‐L1 and thyroid cytology: A possible diagnostic and prognostic marker

[Personalized approach to anaplastic thyroid carcinoma]

BACKGROUND

Anaplastic thyroid carcinoma (ATC) represents the rarest but most aggressive tumor entity of the thyroid gland. In this respect, the treatment of advanced ATC has rapidly evolved in recent years. Recently, new personalized forms of treatment that address the somatic mutational status of the tumor have been increasingly used. The aim of this article is to provide an overview of current molecular-based and personalized treatment options for ATC.

METHODS

A current literature search was performed with a focus on personalized molecular-based treatment options for ATC.

RESULTS

The majority of patients suffering from ATC have an advanced tumor disease at the time of initial diagnosis. Despite multimodal treatment approaches consisting of surgery, external beam radiation therapy (EBRT) and chemotherapy (CTX), the prognosis of ATC is still poor. Accordingly, the focus of innovative treatment approaches is on molecular-based, individualized tumor therapy, including in particular BRAFV600E and multikinase inhibitors. The potential of the latter seems to lie particularly in combination therapy with immune checkpoint inhibitors. These treatment options can be used in both adjuvant and neoadjuvant settings. Neoadjuvant treatment of advanced ATC can achieve a potentially resectable treatment setting and improve the poor prognosis of affected patients; however, larger prospective and randomized studies on these combination therapies are currently pending.

CONCLUSION

The focus of future treatment approaches for ATC will be on individualized, molecular-based tumor therapy. In particular, the neoadjuvant use of these therapies may change the paradigm of ATC surgery as locally advanced as well as metastatic carcinomas can be converted to a potentially resectable status and made amenable to surgery.

Update regarding the role of PD-L1 in oncocytic thyroid lesions on cytological samples

AIMS

Several papers have shown that programmed death-ligand 1 (PD-L1) expression is a relevant predictive biomarker in anti-PD-L1 cancer immunotherapy. While its role in several human cancers is correlated with poor prognosis and resistance to anticancer therapies, in thyroid cancers the role of PD-L1 remains questionable. Few articles have studied PD-L1 in thyroid fine-needle aspiration cytology (FNAC), demonstrating a possible correlation with papillary thyroid carcinoma. However, its role in oncocytic thyroid lesions remains controversial. We accordingly examine the performance of PD-L1 immunostaining in liquid based cytology (LBC) from oncocytic lesions.

METHODS

From January 2019 to March 2021, 114 thyroid lesions diagnosed by FNAC from lesions with a predominant oncocytic component, were enrolled for evaluation by PD-L1 immunostaining on both LBC and corresponding histology samples.

RESULTS

The FNAC cohort included 51 benign (B, negative controls), 4 atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS), 57 follicular lesions (follicular neoplasm/suspicious for FN, FN/SFN) and 2 suspicious for malignancy (SFM) cases. Fifty-four cases (11B, 2 AUS/FLUS, 39 FN/SFN and 2 SFM) had histological follow-up including: 1B case resulted as a hyperplastic oxyphilic nodule in Hashimoto thyroiditis (HT), 10B as goitre, 2 AUS/FLUS cases as oncocytic adenomas (OAs); 39 FN/SFN included 27 OAs, 4 FA and 8 oncocytic follicular carcinoma (OFC). The two SFM cases were diagnosed on histopathology as OAs. Increased plasma membrane and cytoplasmic PD-L1 expression were found in 47 cases of the LBC cases (41.2%). Among the histological series, 67.3% of OAs and 75% of OFC had PD-L1 expression, while negative PD-L1 was found in hyperplastic oncocytic cells in HT. A positivity in more than 30% of the neoplastic cells was found in 72.9% of the cases including six OFC.

CONCLUSIONS

These data suggest that PD-L1 expression is expressed in oncocytic thyroid lesions. While weak PD-L1 expression failed to discriminate benign from malignant lesions, OFC demonstrated more intense cytoplasmic and membranous expression.

Operation rate and cancer prevalence among thyroid nodules with FNAC report of suspicious for malignancy (TIR4) or malignant (TIR5) according to Italian classification system: a systematic review and meta-analysis

BACKGROUND

In the Italian system for reporting thyroid cytology (ICCRTC), nodules suspicious for (TIR4) and consistent with (TIR5) malignancy are thought being 5% and 4-8% of all biopsies and having risk of malignancy of 60-80% and >95%, respectively. However, no evidence-based data exist about these figures. The present systematic review aimed at achieving solid estimates about TIR4 and TIR5 also considering potential influencing factors.

METHODS

The review was conducted according to MOOSE. Databases of Google Scholar and Cochrane were searched. No language restriction was used. The last search was performed on February 26th 2022. Quality assessment was performed. Proportion meta-analyses were performed using random-effect model. Statistical analyses were performed using OpenMeta [Analyst].

RESULTS

The online search retrieved 271 articles and 16 were finally included for quantitative analysis. The risk of bias was generally low. The pooled cancer prevalence in TIR4 was 92.5% (95%CI 89.4-95.6%) with unexplained moderate heterogeneity. The pooled cancer rate among TIR5 was 99.7% (95%CI 99.3-100%) without heterogeneity. The resection rate in TIR4 and TIR5 showed heterogeneity, being the latter explained when using their prevalence among biopsies: the higher the prevalence, the higher the operation rate. The pooled risk difference between TIR5 and TIR4 was significant (OR 11.153).

CONCLUSIONS

These figures can form the basis for the next updated version of ICCRTC. Any institution using ICCRTC should revise its series of TIR4/TIR5 to calculate the cancer rate, and, importantly, consider the modifiers of the risk of malignancy. A cross check among institutions is advised.

Hashimoto’s Thyroiditis Minimizes Lymph Node Metastasis in BRAF Mutant Papillary Thyroid Carcinomas

Hashimoto’s thyroiditis (HT) (autoimmune thyroiditis) is a clinicopathological entity associated with chronic lymphocytic infiltration resulting in hypothyroidism. HT is a double-edged sword that increases the risk of papillary thyroid cancer (PTC), yet it serves as a protective factor for PTC progression. BRAF mutation in PTCs is associated with rapid cell growth, aggressive tumor characteristics, and higher mortality rates. Here, we aimed to analyze the influence of HT in patients with PTCs and its effect on lymph node metastasis (LNM) in BRAF mutant tumors. Adults diagnosed with PTC between 2008 and January 2021 were retrospectively included. A total of 427 patients, 128 of whom had underlying HT, were included. The HT group had significantly higher rates of microcarcinoma (49.2% vs. 37.5%, p = 0.025) and less lateral LNM (8.6% vs. 17.1%, p = 0.024). Interestingly, BRAF-mutated PTCs were found to have significantly less overall LNM (20.9% vs. 51%, p = 0.001), central LNM (25.6% vs. 45.1%, p = 0.040) and lateral LNM (9.3% vs. 29.4%, p = 0.010) in patients with HT when compared to those without underlying HT. HT was found to be an independent protective predictor of overall and lateral LNM. Altogether, HT was able to neutralize the effect of BRAF mutation and was determined to be an independent protective factor against LNM. Specifically, our work may influence treatment-aggressiveness decision making for endocrinologists, oncologists and surgeons alike.

Trends in Diagnosis of Noninvasive Follicular Thyroid Neoplasm With Papillarylike Nuclear Features and Total Thyroidectomies for Patients With Papillary Thyroid Neoplasms

Importance

Increasing detection of early-stage papillary thyroid neoplasms without improvements in mortality has prompted development of strategies to prevent or mitigate overtreatment.

Objective

To determine adoption rates of 2 recent strategies developed to limit overtreatment of low-risk thyroid cancers: (1) a new classification, noninvasive follicular thyroid neoplasm with papillarylike nuclear features (NIFTP), and (2) hemithyroidectomy for selected papillary thyroid carcinomas (PTCs) up to 4 cm in size.

Design, Setting, and Participants

This is a cross-sectional analysis of 3368 pathology records of 2 cohorts of patients from 18 hospitals in 6 countries during 2 time periods (2015 and 2019). Participating hospitals were included from the US (n = 12), Canada (n = 2), Denmark (n = 1), South Korea (n = 1), South Africa (n = 1), and India (n = 1). The records of the first 100 patients per institution for each year who underwent thyroid-directed surgery (hemithyroidectomy, total thyroidectomy, or completion thyroidectomy) were reviewed.

Main Outcomes and Measures

Frequency of diagnosis of NIFTP, PTCs, and thyroidectomies during the study period.

Results

Of the 790 papillary thyroid neoplasms captured in the 2019 cohort, 38 (4.8%) were diagnosed as NIFTP. Diagnosis of NIFTP was observed in the US, South Africa, and India. There was minimal difference in the total proportion of PTCs in the 2015 cohort compared with the 2019 cohort (778 [47.1%] vs 752 [44.5%]; difference, 2.6% [95% CI, -16.9% to 22.1%]). The proportion of PTCs eligible for hemithyroidectomy but treated with total thyroidectomy in the 2 cohorts demonstrated a decreasing trend from 2015 to 2019 (341 of 453 [75.3%] vs 253 of 434 [58.3%]; difference, 17.0% [95% CI, -1.2% to 35.2%]).

Conclusions and Relevance

Results of this cohort study showed that the 2 mitigation strategies for preventing overtreatment of early-stage thyroid cancer have had mixed success. The diagnosis of NIFTP has only been applied to a small proportion of thyroid neoplasms compared with expected rates. However, more patients eligible for hemithyroidectomy received it in 2019 compared with 2015, showing some success with this deescalation strategy.

Non-cytomembrane PD-L1: An atypical target for cancer

Programmed death ligand 1 (PD-L1) has conventionally been considered as a type I transmembrane protein that can interact with its receptor, programmed cell death 1 (PD-1), thus inducing T cell deactivation and immune escape. However, targeting the PD-1/PD-L1 axis has achieved adequate clinical responses in very few specific malignancies. Recent studies have explored the extracellularly and subcellularly located PD-L1, namely, nuclear PD-L1 (nPD-L1), cytoplasmic PD-L1 (cPD-L1), soluble PD-L1 (sPD-L1), and extracellular vesicle PD-L1 (EV PD-L1), which might shed light on the resistance to anti-PD1/PDL1 therapy. In this review, we summarize the four atypical localizations of PD-L1 with a focus on their novel functions, such as gene transcription regulation, therapeutic efficacy prediction, and resistance to various cancer therapies. Additionally, we highlight that non-cytomembrane PD-L1s are of significant cancer diagnostic value and are promising therapeutic targets to treat cancer.

From biomarkers to therapeutic targets: the promise of PD-L1 in thyroid autoimmunity and cancer

The programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) immune checkpoint proteins hold promise as diagnostic, prognostic, and therapeutic targets for precision oncology. By restoring antitumor T cell surveillance, the high degree of effectiveness of the immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment. However, the majority of patients (65-80 %) treated with ICIs experience significant side effects, called immune-related adverse events (irAEs), resulting in autoimmune damage to various organs. Therefore, broadening the clinical applicability of these treatments to all cancer types requires an improved understanding of the mechanisms linking cancer immune evasion and autoimmunity. The thyroid is the endocrine gland the most frequently involved in autoimmunity and cancer, the growing incidence of which is raising serious public health issues worldwide. In addition, the risk of developing thyroid cancer is increased in patients with autoimmune thyroid disease and thyroid dysfunction is one of the most common irAEs, especially with PD‑1/PD-L1 blockade. Therefore, we chose the thyroid as a model for the study of the link between autoimmunity, irAEs, and cancer. We provide an update into the current knowledge of the PD‑1/PD-L1 axis and discuss the growing interest of this axis in the diagnosis, prognosis, and management of thyroid diseases within the context of autoimmunity and cancer, while embracing personalized medicine.

Programmed Death-Ligand 1 (PD-L1) Is a Potential Biomarker of Disease-Free Survival in Papillary Thyroid Carcinoma: a Systematic Review and Meta-Analysis of PD-L1 Immunoexpression in Follicular Epithelial Derived Thyroid Carcinoma

The expression of programmed death-ligand 1 (PD-L1) is an established prerequisite for the administration of checkpoint inhibitor therapy and is of prognostic value in several cancer types. Data concerning the potential effect of PD-L1 on the prognosis of thyroid carcinoma are limited. Therefore, this study aimed to provide a systematic review of the published data on this topic. The literature was reviewed to gather and quantify evidence on the prognostic role of PD-L1 in follicular epithelial derived thyroid carcinomas and determine its association with clinicopathological parameters. A meta-analysis was performed using the DerSimonian-Laird random-effects model. The quality of studies was evaluated with the Newcastle-Ottawa Scale and a modified GRADE approach used to rate the quality of evidence. Out of 445 papers, 18 were included and 15 provided adequate data for meta-analysis. The quality of evidence ranged from low to high. PD-L1 expression was significantly associated with a reduced disease-free survival (DFS) (RR 1.63, CI 1.04-2.56, p = 0.03, I² 68%, τ² 0.19 and HR 1.90, CI 1.33-2.70, p< 0.001, I² 0%, τ² 0.00); however, no association was found with the overall survival (OS). Furthermore, a significant association was found with respect to underlying chronic lymphocytic thyroiditis and BRAFV600E mutation status in papillary thyroid carcinomas. In the subgroup analysis, the association of PD-L1 and DFS remained strong in papillary thyroid carcinoma when compared with dedifferentiated thyroid carcinomas (anaplastic and poorly differentiated thyroid carcinomas) that failed to demonstrate a significant association with respect to PD-L1. These findings underscore the role of PD-L1 immunohistochemistry as a potential prognostic biomarker of disease recurrence in patients with papillary thyroid carcinoma.