PD-L1 and IDO1 Are Expressed in Poorly Differentiated Thyroid Carcinoma

Combination Targeted Therapy with Pembrolizumab and Lenvatinib in Progressive, Radioiodine-Refractory Differentiated Thyroid Cancers

PURPOSE

Lenvatinib, a potent multikinase inhibitor, improves progression-free survival (PFS) in patients with radioiodine (RAI)-refractory differentiated thyroid cancer; however, most patients experience disease progression, warranting further therapy. We evaluated the efficacy and safety of lenvatinib plus pembrolizumab in these patients.

PATIENTS AND METHODS

We enrolled patients with progressive, RAI-refractory differentiated thyroid cancer who were either naïve to multikinase inhibitors (cohort 1) or who had progressed on lenvatinib (cohort 2). Patients received oral lenvatinib daily (cohort 1, 20 mg; cohort 2, dose at progression) and intravenous pembrolizumab (200 mg) every 21 days.

RESULTS

In cohorts 1 and 2, 30 and 27 patients were enrolled, respectively. Adverse events were consistent with those observed in other cancers. In cohort 1, the confirmed overall response rate was 65.5%. There were no complete responses (primary endpoint). The 12- and 18-month PFS were 72.0% and 58.0%, respectively, and the median PFS was 26.8 months. In cohort 2, the confirmed overall response rate was 16% (primary endpoint), and the median PFS was 10.0 months (95% confidence interval, 7.0-17.9 months). Tumor histology, driver mutations, and immune-related biomarkers, including PD-L1 expression, thyroid-specific antibody levels, and CD8+ T-cell tumor infiltrate, did not correlate with response to therapy. Increased baseline peripheral blood monocytes and neutrophil to lymphocyte ratio were associated with a worse PFS in cohort 1.

CONCLUSIONS

Lenvatinib plus pembrolizumab may enhance the durability of lenvatinib monotherapy in lenvatinib-naïve patients. Furthermore, the addition of pembrolizumab may be a viable salvage therapy for patients who have progressed on lenvatinib.

PAK4 Is Involved in the Stabilization of PD-L1 and the Resistance to Doxorubicin in Osteosarcoma and Predicts the Survival of Diagnosed Patients

PAK4 and PD-L1 have been suggested as novel therapeutic targets in human cancers. Moreover, PAK4 has been suggested to be a molecule closely related to the immune evasion of cancers. Therefore, this study evaluated the roles of PAK4 and PD-L1 in the progression of osteosarcomas in 32 osteosarcomas and osteosarcoma cells. In human osteosarcomas, immunohistochemical positivity for the expression of PAK4 (overall survival, p = 0.028) and PD-L1 (relapse-free survival, p = 0.002) were independent indicators for the survival of patients in a multivariate analysis. In osteosarcoma cells, the overexpression of PAK4 increased proliferation and invasiveness, while the knockdown of PAK4 suppressed proliferation and invasiveness. The expression of PAK4 was associated with the expression of the molecules related to cell cycle regulation, invasion, and apoptosis. PAK4 was involved in resistance to apoptosis under a treatment regime with doxorubicin for osteosarcoma. In U2OS cells, PAK4 was involved in the stabilization of PD-L1 from ubiquitin-mediated proteasomal degradation and the in vivo infiltration of immune cells such as regulatory T cells and PD1-, CD4-, and CD8-positive cells in mice tumors. In conclusion, this study suggests that PAK4 is involved in the progression of osteosarcoma by promoting proliferation, invasion, and resistance to doxorubicin and stabilized PD-L1 from proteasomal degradation.

Management of Poorly Differentiated Thyroid Cancer and Differentiated High-Grade Thyroid Carcinoma

Thyroid carcinoma of follicular cell origin exists on a histopathologic and clinical spectrum. The authors focus on the category of tumors that fall between the very favorable well-differentiated thyroid carcinomas and the very unfavorable anaplastic thyroid carcinomas. These intermediately aggressive tumors include poorly differentiated thyroid carcinoma and the newly defined differentiated high-grade thyroid carcinoma. Both diagnoses require certain histopathologic requirements be met in order to accurately identify these tumors post-operatively. Management remains primarily surgical though adjunctive treatments such as molecular targeted therapies (eg, tyrosine kinase inhibitors) and differentiation therapy (to restore tumor response to radioactive iodine) are also becoming available.

Exploring markers of immunoresponsiveness in papillary thyroid carcinoma and future treatment strategies

BACKGROUND

The study summarizes the potential use of immunotherapy for BRAF-mutated papillary thyroid cancer (PTC) by analyzing the immune profile of City of Hope PTC patient samples and comparing them to the thyroid dataset available in the TCGA database.

MATERIALS AND METHODS

PTC cases with available formalin-fixed paraffin-embedded archived tumor tissue were identified. RNA was extracted from the tumor tissue and analyzed by NanoString to evaluate their immune gene expression profile. Immunohistochemistry was used to determine the expression of immune suppressive genes and lymphocytic infiltration into the tumor tissue. Thyroid cancer cell lines (MDA-T32, MDA-T68, MDA-T85, and MDA-T120) were used to determine the correlation between the BRAF inhibition and CD274 expression.

RESULTS

The study found that PTC cases with BRAF mutations had higher expression of immune checkpoint markers CD274 and CTLA4, as well as higher tumor-infiltrating lymphocytes, particularly CD4+T cells. Additionally, the study identified immunosuppressive markers expressed by tumor cells like CD73, CD276, and CD200 that could be targeted for immunotherapy. Further experiments using PTC cell lines lead to the conclusion that CD274 expression correlates with BRAF activity and that inhibitors of BRAF could potentially be used in combination with immunotherapy to treat PTC.

CONCLUSIONS

These findings suggest that PTC cases with BRAF mutations or high expression may be correlated with an immune hot signature and could benefit from immunotherapeutic strategies.

Epacadostat plus pembrolizumab versus placebo plus pembrolizumab for advanced urothelial carcinoma: results from the randomized phase III ECHO-303/KEYNOTE-698 study

BACKGROUND

Indoleamine 2,3-dioxygenase 1 (IDO1) levels correlate with poor outcomes in urothelial carcinoma (UC). IDO1 and programmed death-ligand 1 (PD-L1) are often co-expressed. Epacadostat is a potent and highly selective inhibitor of IDO1. In a subgroup analysis of patients with advanced UC participating in a phase I/II study, epacadostat-pembrolizumab treatment produced an objective response rate (ORR) of 35%.

METHODS

ECHO-303/KEYNOTE-698 was a double-blinded, randomized phase III study of adults with metastatic or unresectable locally advanced UC with recurrence or progression following first-line platinum-based chemotherapy. Participants were randomized to epacadostat 100 mg twice daily (BID) plus pembrolizumab or placebo plus pembrolizumab until completion of 35 pembrolizumab infusions, disease progression, or unacceptable toxicity. The primary endpoint was investigator-assessed ORR per Response Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

Target enrollment was 648 patients; enrollment was halted early based on efficacy results from the phase III ECHO-301/KEYNOTE-252 study in metastatic melanoma. Forty-two patients were randomized to each treatment arm. Median duration of follow-up was 62 days in each arm. The investigator-assessed ORR (unconfirmed) was 26.2% (95% CI 16.35-48.11) for epacadostat plus pembrolizumab and 11.9% (95% CI 4.67-29.50) for placebo plus pembrolizumab. Two complete responses were reported, both in the placebo-plus-pembrolizumab arm. Circulating kynurenine levels increased from C1D1 to C2D1 in the placebo-plus-pembrolizumab arm and numerically decreased in the epacadostat-plus-pembrolizumab arm. The safety profile of epacadostat plus pembrolizumab was similar to that of pembrolizumab monotherapy, although a numerically greater proportion of patients in the combination vs. control arm experienced treatment-related grade ≥ 3 adverse events (16.7% vs. 7.3%). One patient in each arm died due to cardiovascular events, which were not deemed drug-related. No new safety concerns were identified for either agent.

CONCLUSIONS

Epacadostat plus pembrolizumab demonstrated anti-tumor activity and was generally tolerable as second-line treatment of patients with unresectable locally advanced or recurrent/progressive metastatic UC. Epacadostat 100 mg BID, when administered with pembrolizumab, did not normalize circulating kynurenine in most patients. Further study of combined IDO1/PD-L1 inhibition in this patient population, particularly with epacadostat doses that result in durable normalization of circulating kynurenine, may be warranted.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03374488. Registered 12/15/2017.

Pembrolizumab plus either epacadostat or placebo for cisplatin-ineligible urothelial carcinoma: results from the ECHO-307/KEYNOTE-672 study

BACKGROUND

Indoleamine 2,3- dioxygenase 1 (IDO1) is an immunosuppressive enzyme that has been correlated with shorter disease-specific survival in patients with urothelial carcinoma (UC). IDO1 may counteract the antitumor effects of immune checkpoint inhibitors. Epacadostat is a potent and highly selective inhibitor of IDO1. In the phase I/II ECHO-202/KEYNOTE-037 study, epacadostat plus pembrolizumab resulted in a preliminary objective response rate (ORR) of 35% in a cohort of patients with advanced UC.

METHODS

ECHO-307/KEYNOTE-672 was a double-blinded, randomized, phase III study. Eligible adults had confirmed locally advanced/unresectable or metastatic UC of the urinary tract and were ineligible to receive cisplatin-based chemotherapy. Participants were randomly assigned (1:1) to receive epacadostat (100 mg twice daily) plus pembrolizumab (200 mg every 3 weeks) or placebo plus pembrolizumab for up to 35 pembrolizumab infusions. The primary endpoint was investigator-assessed ORR per Response Evaluation Criteria in Solid Tumors (version 1.1).

RESULTS

A total of 93 patients were randomized (epacadostat plus pembrolizumab, n = 44; placebo plus pembrolizumab, n = 49). Enrollment was stopped early due to emerging data from the phase III ECHO-301/KEYNOTE-252 study. The median duration of follow-up was 64 days in both arms. Based on all available data at cutoff, ORR (unconfirmed) was 31.8% (95% CI, 22.46-55.24%) for epacadostat plus pembrolizumab and 24.5% (95% CI, 15.33-43.67%) for placebo plus pembrolizumab. Circulating kynurenine levels numerically increased from C1D1 to C2D1 in the placebo-plus-pembrolizumab arm and decreased in the epacadostat-plus-pembrolizumab arm. Epacadostat-plus-pembrolizumab combination treatment was well tolerated with a safety profile similar to the placebo arm. Treatment discontinuations due to treatment-related adverse events were more frequent with epacadostat (11.6% vs. 4.1%).

CONCLUSIONS

Treatment with epacadostat plus pembrolizumab resulted in a similar ORR and safety profile as placebo plus pembrolizumab in cisplatin-ineligible patients with previously untreated locally advanced/unresectable or metastatic UC. At a dose of 100 mg twice daily, epacadostat did not appear to completely normalize circulating kynurenine levels when administered with pembrolizumab. Larger studies with longer follow-up and possibly testing higher doses of epacadostat, potentially in different therapy settings, may be warranted.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03361865, retrospectively registered December 5, 2017.

Nearly Half of Patients with Anaplastic Thyroid Cancer May Be Amenable to Immunotherapy

IMPORTANCE

Poorly differentiated cancer (PDC) and anaplastic thyroid cancer (ATC) have an aggressive course of disease with limited treatment options. The expression of programmed cell death ligand-1 (PD-L1) has been used to determine the responses of many cancers to immunotherapy. The aim of the study was to investigate the expression of PD-L1 in a cohort of patients with PDC and ATC to assess their suitability for immunotherapy. Data, settings, and participants: This study is a retrospective cohort review of patients treated for PDC and ATC treated at a tertiary referral institution during the period 2000-2020. PD-L1 22C3 pharmDx qualitative immunohistochemistry was performed on formalin-fixed, paraffin-embedded (FFPE) specimens of tumours to detect the presence of the PD-L1 protein.

MAIN OUTCOME MEASURES

The percentage of tumours that were positive for PD-L1 immunohistochemistry and the PD-L1 protein expression as measured by using the Tumour Proportion Score (TPS). Secondary outcomes studied were the associations between demographic, clinicopathological, treatment and disease outcomes and PD-L1 expression.

RESULTS

Nineteen patients (12F:7M) with a mean age of 65.4 (±14.3 SD) years were diagnosed with PDC in 4 (21%) and fifteen were diagnosed with ATC (79%) during the study period. Fifteen (79%) patients underwent some form of surgery, with R0 resection achieved in only three of the fifteen (20%) patients. Overall, PD-L1 expression was seen in seven of the fifteen (47%) of the patients with ATC, with no positivity seen in the patients with PDC. PD-L1 expression had no impact on treatment modality and positive expression was not significantly associated with stage of disease, metastasis, or survival.

CONCLUSION

Nearly half of patients with ATC express PD-L1 and may be amenable to immunotherapy with pembrolizumab.

Poorly differentiated thyroid carcinoma: molecular, clinico-pathological hallmarks and therapeutic perspectives

Poorly differentiated thyroid carcinoma (PDTC) is a rare and extremely aggressive tumor, accounting for about 2-15% of all thyroid cancer. PDTC has a distinct biological behavior compared to well-differentiated and anaplastic thyroid carcinoma and, in last years, it has been classified as a separate entity from both anatomopathological and clinical points of view. Nevertheless, there is still a lack of consensus among clinicians regarding inclusion criteria and definition of PDTC that affects its diagnosis and clinical management. Due to its rarity and difficulty in classification compared to other tumors, very few studies are available to date and series often include different histotypes in addition to PDTC. This review focuses on main studies concerning PDTC summarizing the evolution in the definition of its diagnosis criteria, clinicopathological features, management, and outcome. The data available confirm that the pathological evaluation and classification of PDTC are crucial and should therefore be standardized. Since the clinical presentation and prognosis of PDTC may vary widely depending on the different stage of the disease at diagnosis, the patient's management may differ in treatment and should be tailored to each patient. Finally, this review discusses advances in molecular insights of PDTC that, together with the implementation of both in vitro and in vivo models, will provide valuable insights into biological mechanisms of progression, metastasis, and invasion of this aggressive thyroid carcinoma. Further studies on larger, carefully selected series are needed to better assess the peculiar features of PDTC and to better define its management by focusing on the best diagnostic and therapeutic approaches.

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.

Phase I/II sequencing study of azacitidine, epacadostat, and pembrolizumab in advanced solid tumors

BACKGROUND

Indoleamine 2,3-dioxygenase 1 (IDO1), an interferon-inducible enzyme, contributes to tumor immune intolerance. Immune checkpoint inhibition may increase interferon levels; combining IDO1 inhibition with immune checkpoint blockade represents an attractive strategy. Epigenetic agents trigger interferon responses and may serve as an immunotherapy priming method. We evaluated whether epigenetic therapy plus IDO1 inhibition and immune checkpoint blockade confers clinical benefit to patients with advanced solid tumors.

METHODS

ECHO-206 was a Phase I/II study where treatment-experienced patients with advanced solid tumors (N = 70) received azacitidine plus an immunotherapy doublet (epacadostat [IDO1 inhibitor] and pembrolizumab). Sequencing of treatment was also assessed. Primary endpoints were safety/tolerability (Phase I), maximum tolerated dose (MTD) or pharmacologically active dose (PAD; Phase I), and investigator-assessed objective response rate (ORR; Phase II).

RESULTS

In Phase I, no dose-limiting toxicities were reported, the MTD was not reached; a PAD was not determined. ORR was 5.7%, with four partial responses. The most common treatment-related adverse events (AEs) were fatigue (42.9%) and nausea (42.9%). Twelve (17.1%) patients experienced ≥1 fatal AE, one of which (asthenia) was treatment-related.

CONCLUSIONS

Although the azacitidine-epacadostat-pembrolizumab regimen was well tolerated, it was not associated with substantial clinical response in patients with advanced solid tumors previously exposed to immunotherapy.

The Tumor Microenvironment and the Estrogen Loop in Thyroid Cancer

Thyroid cancer (TC) cells employ multiple signaling pathways, such as PI3K/AKT/mTOR and RAS/Raf/MAPK, fostering cell proliferation, survival and metastasis. Through a complex interplay with immune cells, inflammatory mediators and stroma, TC cells support an immunosuppressive, inflamed, pro-carcinogenic TME. Moreover, the participation of estrogens in TC pathogenesis has previously been hypothesized, in view of the higher TC incidence observed among females. In this respect, the interactions between estrogens and the TME in TC could represent a relevant, unexplored area of research. We thereby collectively reviewed the available evidence concerning the potential carcinogenic role of estrogens in TC, specifically focusing on their crosstalk with the TME.

Identification of calcium metabolism related score associated with the poor outcome in papillary thyroid carcinoma

Introduction

Papillary thyroid carcinoma is a type of thyroid cancer that exhibits significant variability in prognosis. Extensive research indicates that the impaired signaling of 1,25(OH)2D3-VDR may be a crucial factor in the development and progression of PTC.

Methods

To investigate this further, Integrated analysis mRNA expression information from The Cancer Genome Atlas and GEO, we compared gene expression in cancer and normal tissues and identified differentially expressed genes (DEGs). Through this analysis, we identified DEGs and calculated risk estimates for seven genetic markers.

Results

Subsequently, we constructed predictive models using LASSO-Cox regression to test the predictive value of these markers. Our results revealed that 64 calcium metabolism-related genes showed significant differences between tumor and normal tissues. Ten of the identified DEGs were significantly associated with overall survival, indicating their potential role in disease progression. Using the average risk score for the seven genetic markers, we divided patients into high- and low-risk groups. We found that patients in the low-risk group had significantly better overall survival than those in the high-risk group, highlighting the importance of these genetic markers in predicting prognosis. Further analysis using Cox regression demonstrated that the risk levels had independent predictive power. Additionally, we conducted functional analysis of the identified genetic markers, which showed significant differences in immune status between the two patient groups. We also investigated the effect of these calcium metabolism-related genes on thyroid cancer biological functions, immune microenvironment, and drug resistance.

Discussion

Our findings provide evidence of a novel genetic signature associated with calcium metabolism, which can predict prognosis in patients with PTC. These results may have significant implications for the development of new diagnostic and therapeutic approaches to improve outcomes for PTC patients.

IDO1/COX2 Expression Is Associated with Poor Prognosis in Colorectal Cancer Liver Oligometastases

Background: IDO1 and COX2 have emerged as promising immunotherapy targets. It is unclear whether IDO1 and COX2 expression levels in colorectal cancer (CRC) patients with liver oligometastases could be independent predictors of overall survival (OS) and progression-free survival (PFS). The purpose of this study was to investigate the correlation of IDO1 and COX2 expression levels with OS and PFS in CRC patients with liver oligometastases. Methods: The expression levels of IDO1 and COX2 were assessed by immunohistochemistry in 107 specimens from patients with liver oligometastases. The correlation between the expression of IDO1 and COX2 and the clinicopathological parameters and OS/PFS in patients was examined. Results: The expression level of IDO1/COX2 was significantly correlated with age and was not associated with gender, BMI, T stage, N stage, primary tumor size, liver metastasis size, CEA, CA19-9, CD3 TILs or CD8 TILs. In univariate analysis, we found that IDO1/COX2 expression, CEA and N stage all yielded significantly poor OS and PFS outcomes. In our multivariate Cox model, IDO1/COX2 coexpression, CEA and N stage were found to be significantly correlated with OS; IDO1/COX2 coexpression and CEA were significantly correlated with PFS. Conclusions: IDO1/COX2 coexpression plays a pivotal role and may act as a potential prognostic biomarker for survival in CRC patients with liver oligometastases.

Serum Response Factor-Regulated IDO1/Kyn-Ahr Pathway Promotes Tumorigenesis of Oral Squamous Cell Carcinoma

Serum response factor (SRF) regulates pro-carcinogenic genes in various cancers, but its role in oral squamous cell carcinoma (OSCC) remains unclear. SRF expression in 70 OSCC samples was detected via immunohistochemistry. Abundant SRF expressed in OSCC tissues was closely associated with tumor metastasis. SRF-overexpressing OSCC cells were constructed to evaluate how SRF affects OSCC cell tumorigenesis and epithelial-to-mesenchymal transition (EMT) in vitro and in vivo. Overexpressed SRF increased OSCC cell migration and invasion in vitro and tumor growth and invasion in vivo. This promoted EMT, characterized by decreased and increased expression of E- and N-cadherin, respectively. Furthermore, an analysis of RNA sequences of transcriptional targets of SRF showed that SRF transactivated the indoleamine 2, 3-dioxygenase 1 (IDO1)/kynurenine-aryl hydrocarbon receptor (Kyn-AhR) signaling pathway in OSCC cell lines. Direct SRF binding to the IDO1 gene promoter upregulated transcription, which was detected through chromatin immunoprecipitation and dual luciferase reporter assays. Inhibiting IDO1 or AhR impaired SRF-induced migration and invasion and prevented EMT in OSCC cells. Our results demonstrated that SRF is a critical regulator of the IDO1/Kyn-AhR signaling pathway. This in turn increases OSCC cell migration and invasion by modulating EMT, which, consequently, favors OSCC cell growth and metastasis. We revealed a novel molecular mechanism through which SRF modulates OSCC metastasis. This should provide potential targets or biomarkers for OSCC diagnosis and treatment.

Kinase inhibitors in thyroid cancers

Objective

The treatment landscape for thyroid cancers has changed rapidly with the availability of kinase inhibitors against VEGFR, BRAF, MEK, NTRK, and RET. We provide an up-to-date review of the role of kinase inhibitors in thyroid cancer and discuss upcoming trials.

Design & Methods

A comprehensive review of the available literature describing kinase inhibitors in thyroid cancer was performed.

Results and Conclusions

Kinase inhibitors have become the standard of care for patients with metastatic radioactive iodine-refractory thyroid cancer. Short-term treatment can re-sensitize differentiated thyroid cancer to radioactive iodine, thereby potentially improving outcomes and sparing toxicities associated with the long-term use of kinase inhibitors. The approval of cabozantinib as salvage therapy for progressive radioactive iodine-refractory differentiated thyroid cancer following failure with sorafenib or lenvatinib adds to the available armamentarium of active agents. Vandetanib and cabozantinib have become mainstay treatments for metastatic medullary thyroid cancer regardless of RET mutation status. Selpercatinib and pralsetinib, potent and selective receptor kinase inhibitors with activity against RET, have revolutionized the treatment paradigm for medullary thyroid cancers and other cancers with driver mutations in RET. Dabrafenib plus trametinib for BRAF mutated anaplastic thyroid cancer provides an effective treatment option for this aggressive cancer with a dismal prognosis. In order to design the next generation of agents for thyroid cancer, future efforts will need to focus on developing a better understanding of the mechanisms of resistance to kinase inhibition including bypass signaling and escape mutations.

Management of Progressive Radioiodine-Refractory Thyroid Carcinoma: Current Perspective

Patients with thyroid cancer (TC) usually have an excellent prognosis; however, 5-10% of them develop an advanced disease. The prognosis of this subgroup is still favourable if the lesions respond to radioactive iodine (RAI) treatment. Nearly two-thirds of advanced TC patients become RAI-refractory (RAI-R), and their management is challenging. A multidisciplinary approach in the context of a tumour board is essential to define a personalized strategy. Systemic therapy is not always the best option. In case of slow neoplastic growth and low tumour burden, active surveillance may represent a valuable choice. Local approaches might be considered if the disease progression is limited to a single or few lesions, also in combination and during systemic therapy. Antiresorptive treatment may be started in presence of bone metastases. In case of rapid and/or symptomatic progression involving multiple lesions and/or organs, systemic therapy has to be considered, in absence of contraindications. The multi-kinase inhibitors (MKIs) lenvatinib and sorafenib are currently available as first-line treatment for advanced progressive RAI-R TC. Among second-line options, cabozantinib has been recently approved in RAI-R TC who progressed during MKIs targeting the vascular endothelial growth factor receptor (VEGFR). In the last few years, next-generation sequencing (NGS) assays have been increasingly employed, permitting identification of the genetic alterations harboured by TC, with a significant impact on patients' management. Novel selective targeted therapies have been introduced for the treatment of RAI-R TC in selected cases: REarranged during Transfection (RET) inhibitors (selpercatinib and pralsetinib) and Tropomyosin Receptor Kinase (TRK) inhibitors (larotrectinib and entrectinib) have recently expanded the panorama of the therapeutic options. Moreover, immune checkpoint inhibitors (ICIs) have shown promising results, and they are still under investigation.

Rationale Efficacy and Safety Evidence of Lenvatinib and Pembrolizumab Association in Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) are highly aggressive malignant tumors with poor overall prognosis despite multimodal therapy. As ATC are extremely rare, no randomized controlled study has been published for metastatic disease. Thyrosine kinase inhibitors, especially lenvatinib and immune checkpoint inhibitors such as pembrolizumab, are emerging drugs for ATC. Few studies have reported the efficacity of pembrolizumab and lenvatinib association, resulting in its frequent off-label use. In this review, we discuss rationale efficacy and safety evidence for the association of lenvatinib and pembrolizumab in ATC. First, we discuss preclinical rationale for pembrolizumab monotherapy, lenvatinib monotherapy and synergistic action of pembrolizumab and lenvatinib in the metastatic setting. We also discuss clinical evidence for immunotherapy and pembrolizumab in ATC through the analysis of studies evaluating immunotherapy, lenvatinib and pembrolizumab lenvatinib association in ATC. In addition, we discuss the safety of this association and potential predictive biomarkers of efficiency.

Poorly differentiated thyroid carcinoma: a clinician's perspective

Poorly differentiated thyroid carcinoma (PDTC) is a rare thyroid carcinoma originating from follicular epithelial cells. No explicit consensus can be achieved to date due to sparse clinical data, potentially compromising the outcomes of patients. In this comprehensive review from a clinician's perspective, the epidemiology and prognosis are described, diagnosis based on manifestations, pathology, and medical imaging are discussed, and both traditional and emerging therapeutics are addressed as well. Turin consensus remains the mainstay diagnostic criteria for PDTC, and individualized assessments are decisive for treatment option. The prognosis is optimal if complete resection is performed at early stage but dismal in nearly half of patients with locally advanced and/or distant metastatic diseases, in which adjuvant therapies such as 131I therapy, external beam radiation therapy, and chemotherapy should be incorporated. Emerging therapeutics including molecular targeted therapy, differentiation therapy, and immunotherapy deserve further investigations to improve the prognosis of PDTC patients with advanced disease.

Superinduction of immunosuppressive glioblastoma extracellular vesicles by IFN-γ through PD-L1 and IDO1

Background

Glioblastoma (GBM), the most common primary brain tumor, has a median survival of 15-16 months. Immunotherapy is promising but GBM-mediated immunosuppression remains a barrier. GBMs express the interferon-gamma (IFN-γ)-responsive immunosuppressive molecules PD-L1 and IDO1. Extracellular vesicles (EVs) have also been implicated in GBM-mediated immunosuppression, in part through PD-L1. We therefore sought to determine if GBM IFN-γ exposure increased GBM EV-mediated immunosuppression and mechanisms underlying this.

Methods

Human GBM-derived cells were cultured in the presence/absence of IFN-γ. EV’s were harvested. PD-L1, IDO1, and EV-associated protein expression was assessed. GBM EV’s (+/-IFN-γ) were cultured with healthy donor monocytes. Immunosuppressive myeloid-derived suppressor cell (MDSC) and non-classical monocyte (NCM) frequency was determined. Impact of GBM (+/-IFN-γ) EV-treated monocytes on CD3/CD28-mediated T cell proliferation was assessed. The impact of PD-L1 and IDO1 knockdown in GBM EV’s in this system was evaluated.

Results

IFN-γ exposure increased PD-L1 and IDO1 expression in GBM cells and EV’s without altering EV size or frequency. IFN-γ-exposed GBM EVs induced more MDSC and NCM differentiation in monocytes and these monocytes caused more T cell inhibition than IFN-γ-naive GBM EVs. PD-L1 and/or IDO1 knockdown in GBM cells abrogated the immunosuppressive effects of IFN-γ-exposed GBM EVs on monocytes.

Conclusions

IFN-γ exposure such as might occur during an anti-tumor immune response results in superinduction of GBM EVs’ baseline immunosuppressive effects on monocytes. These effects are mediated by increased PD-L1 and IDO1 expression in GBM EV’s. This data highlights mechanisms of GBM EV-mediated immunosuppression and identifies therapeutic targets (PD-L1, IDO1) to reverse these effects.

Indoleamine 2,3-Dioxygenase 1: A Promising Therapeutic Target in Malignant Tumor

Tumorigenesis is a complex multifactorial and multistep process in which tumors can utilize a diverse repertoire of immunosuppressive mechanisms to evade host immune attacks. The degradation of tryptophan into immunosuppressive kynurenine is considered an important immunosuppressive mechanism in the tumor microenvironment. There are three enzymes, namely, tryptophan 2,3-dioxygenase (TDO), indoleamine 2,3-dioxygenase 1 (IDO1), and indoleamine 2,3-dioxygenase 2 (IDO2), involved in the metabolism of tryptophan. IDO1 has a wider distribution and higher activity in catalyzing tryptophan than the other two; therefore, it has been studied most extensively. IDO1 is a cytosolic monomeric, heme-containing enzyme, which is now considered an authentic immune regulator and represents one of the promising drug targets for tumor immunotherapy. Collectively, this review highlights the regulation of IDO1 gene expression and the ambivalent mechanisms of IDO1 on the antitumoral immune response. Further, new therapeutic targets via the regulation of IDO1 are discussed. A comprehensive analysis of the expression and biological function of IDO1 can help us to understand the therapeutic strategies of the inhibitors targeting IDO1 in malignant tumors.

Immune Checkpoint Protein Expression Defines the Prognosis of Advanced Thyroid Carcinoma

BACKGROUND

Patients with advanced thyroid carcinoma (TC), such as anaplastic thyroid carcinoma (ATC), poorly differentiated thyroid carcinoma (PDTC), and locally advanced papillary thyroid carcinoma (PTC), have poor prognoses and require novel treatments. Immune checkpoint (ICP) inhibitors have demonstrated encouraging and good results; nevertheless, their effect in advanced TCs remains largely unclear. Thus, we demonstrated ICP profiles and investigated their potential clinical significance.

METHODS

A total of 234 TC patients were involved, with 22 ATCs, 44 PDTCs, and 168 PTCs, including 58 advanced PTCs. Immunohistochemistry was performed to evaluate nine ICPs [programmed cell death ligand 1 (PDL1), Programmed cell death 1 (PD1), cytotoxic T lymphocyte-associated protein 4 (CTLA4), B and T lymphocyte attenuator (BTLA), T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), lymphocyte activation gene 3 (LAG3), V-domain immunoglobulin suppressor of T-cell activation (VISTA), B7 homolog 3 (B7-H3), and T-cell immunoglobulin and mucin domain- 3 protein (TIM3)] expression via tissue microarrays (TMAs), and clinical correlations were analyzed simultaneously.

RESULTS

ATC had the highest positive rate of ICPs among the three pathological types, as well as relatively high ICP co-expression. ATC with high expression of PDL1 positivity had a poor prognosis. Shorter survival was associated with VISTA, B7H3, TIM3, and TIGIT expression in PDTC. The greater the co-expression of these four ICPs, the poorer the prognosis in PDTC patients. VISTA and B7H3 were the two most commonly expressed ICPs in advanced PTC, both of which were linked to a poor prognosis.

CONCLUSIONS

PDL1 is linked to the overall survival (OS) of ATC. A subset of PDTC is likely immunogenic with poor prognosis and co-expression of VISTA, B7H3, TIM3, and TIGIT. Furthermore, VISTA and B7H3 are prognostic biomarkers in advanced PTC. Single or combined blockade targeting these ICPs might be effective for advanced TCs in the future.

What is the status of immunotherapy in thyroid neoplasms?

Immunotherapy has changed the treatment of patients with advanced cancer, with different phase III trials showing durable responses across different histologies. This review focuses on the preclinical and clinical evidence of potential predictive biomarkers of response and efficacy of immunotherapy in thyroid neoplasms. Programmed death-ligand 1 (PD-L1) staining by immunohistochemistry has shown higher expression in anaplastic thyroid cancer (ATC) compared to other subtypes. The tumor mutational burden in thyroid neoplasms is low but seems to be higher in ATC. Immune infiltrates in the tumor microenvironment (TME) differ between the different thyroid neoplasm subtypes. In general, differentiated thyroid cancer (DTC) has a higher number of tumor-associated lymphocytes and regulatory T cells (Tregs), while ATC and medullary thyroid cancer (MTC) display a high density of tumor-associated macrophages (TAMs). Nevertheless, results from clinical trials with immunotherapy as monotherapy or combinations have shown limited efficacy. Further investigation into new strategies aside from anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4)/programmed death 1 (PD-1)/PD-L1 antibodies, validation of predictive biomarkers, and better population selection for clinical trials in thyroid neoplasms is more than needed in the near future.

Tumor microenvironment in giant cell tumor of bone: evaluation of PD-L1 expression and SIRPα infiltration after denosumab treatment

Giant cell tumor of bone (GCTB) is an intermediate malignant bone tumor that is locally aggressive and rarely metastasizes. Denosumab, which is a receptor activator of nuclear factor kappa B ligand (RANKL) inhibitor, can be used to treat GCTB. We focused on potential immunotherapy for GCTB and investigated the tumor microenvironment of GCTB. Programmed death-ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO1) expression and signal-regulatory protein alpha (SIRPα), forkhead box P3 (FOXP3), and cluster of differentiation 8 (CD8) infiltration were assessed by immunohistochemical studies of 137 tumor tissues from 96 patients. Of the naive primary specimens, 28% exhibited PD-L1 expression and 39% exhibited IDO1 expression. There was significantly more SIRPα⁺, FOXP3⁺, and CD8⁺ cell infiltration in PD-L1- and IDO1-positive tumors than in PD-L1- and IDO1-negative tumors. The frequency of PD-L1 expression and SIRPα⁺ cell infiltration in recurrent lesions treated with denosumab was significantly higher than in primary lesions and recurrent lesions not treated with denosumab. PD-L1 expression and higher SIRPα⁺ cell infiltration were significantly correlated with shorter recurrence-free survival. PD-L1 and SIRPα immune checkpoint inhibitors may provide clinical benefit in GCTB patients with recurrent lesions after denosumab therapy.

Combination of Lenvatinib and Pembrolizumab Is an Effective Treatment Option for Anaplastic and Poorly Differentiated Thyroid Carcinoma

Background: Anaplastic thyroid carcinoma (ATC) and metastatic poorly differentiated thyroid carcinomas (PDTCs) are rare aggressive malignancies with poor overall survival (OS) despite extensive multimodal therapy. These tumors are highly proliferative, with frequently increased tumor mutational burden (TMB) compared with differentiated thyroid carcinomas, and elevated programmed death ligand 1 (PD-L1) levels. These tumor properties implicate responsiveness to antiangiogenic and antiproliferative multikinase inhibitors such as lenvatinib, and immune checkpoint inhibitors such as pembrolizumab. Patients and Methods: In a retrospective study, we analyzed six patients with metastatic ATC and two patients with PDTC, who received a combination therapy of lenvatinib and pembrolizumab. Lenvatinib was started at 14-24 mg daily and combined with pembrolizumab at a fixed dose of 200 mg every three weeks. Maximum treatment duration with this combination was 40 months, and 3 of 6 ATC patients are still on therapy. Patient tumors were characterized by whole-exome sequencing and PD-L1 expression levels (tumor proportion score [TPS] 1-90%). Results: Best overall response (BOR) within ATCs was 66% complete remissions (4/6 CR), 16% stable disease (1/6 SD), and 16% progressive disease (1/6 PD). BOR within PDTCs was partial remission (PR 2/2). The median progression-free survival was 17.75 months for all patients, and 16.5 months for ATCs, with treatment durations ranging from 1 to 40 months (1, 4, 11, 15, 19, 25, 27, and 40 months). Grade III/IV toxicities developed in 4 of 8 patients, requiring dose reduction/discontinuation of lenvatinib. The median OS was 18.5 months, with three ATC patients being still alive without relapse (40, 27, and 19 months) despite metastatic disease at the time of treatment initiation (UICC and stage IVC). All patients with long-term (>2 years) or complete responses (CRs) had either increased TMB or a PD-L1 TPS >50%. Conclusions: Our results implicate that the combination of lenvatinib and pembrolizumab might be safe and effective in patients with ATC/PDTC and can result in complete and long-term remissions. The combination treatment is now being systematically examined in a phase II clinical trial (Anaplastic Thyroid Carcinoma Lenvatinib Pembrolizumab [ATLEP]) in ATC/PDTC patients.

PD-L1 expression and immune cells in anaplastic carcinoma and poorly differentiated carcinoma of the human thyroid gland: A retrospective study

Anaplastic thyroid carcinoma (ATC) and poorly differentiated thyroid carcinoma (PDTC) have limited treatment options, and immune profiling may help select patients for immunotherapy. The prevalence and relevance of programmed death-1 ligand (PD-L1) expression and the presence of immune cells in ATC and PDTC has not yet been well established. The present study investigated PD-L1 expression (clone 22C3) and cells in the tumor microenvironment (TME), including tumor-infiltrating lymphocytes (TILs), tumor-associated macrophages (TAMs) and dendritic cells, in whole tissue sections of 15 cases of ATC and 13 cases of PDTC. Immunohistochemical PD-L1 expression using a tumor proportion score (TPS) with a 1% cut-off was detected in 9/15 (60%) of ATC cases and 1/13 (7.7%) of PDTC cases (P=0.006). PD-L1 expression in TILs was limited to the ATC group (73.3 vs. 0% in ATC and PDTC, respectively). In the ATC group, the TPS for tumor positive PD-L1 expression revealed a non-significant trend towards worse survival, but no difference was observed when investigating PD-L1 expression in TILs and TAMs. In addition to increased PD-L1 expression, all ATC cases exhibited significantly increased CD3⁺ and CD8⁺ T cells, CD68⁺ and CD163⁺ macrophages, and S100⁺ dendritic cells compared with the PDTC cases. Loss of mutL homolog 1 and PMS1 homolog 2 expression was observed in one ATC case with the highest PD-L1 expression, as well as in the only PDTC case positive for PD-L1. Notably, the latter was the only PDTC case exhibiting positivity for p53 and a cellular microenvironment similar to ATC. The current results indicated that PD-L1 expression was frequent in ATC, but rare in PDTC. In addition to PD-L1, the present study suggested that microsatellite instability may serve a role in both the TME and the identification of immunotherapy candidates among patients with PDTC.

The Genomic Landscape of Thyroid Cancer Tumourigenesis and Implications for Immunotherapy

Thyroid cancer is the most prevalent endocrine malignancy that comprises mostly indolent differentiated cancers (DTCs) and less frequently aggressive poorly differentiated (PDTC) or anaplastic cancers (ATCs) with high mortality. Utilisation of next-generation sequencing (NGS) and advanced sequencing data analysis can aid in understanding the multi-step progression model in the development of thyroid cancers and their metastatic potential at a molecular level, promoting a targeted approach to further research and development of targeted treatment options including immunotherapy, especially for the aggressive variants. Tumour initiation and progression in thyroid cancer occurs through constitutional activation of the mitogen-activated protein kinase (MAPK) pathway through mutations in BRAF, RAS, mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway and/or receptor tyrosine kinase fusions/translocations, and other genetic aberrations acquired in a stepwise manner. This review provides a summary of the recent genetic aberrations implicated in the development and progression of thyroid cancer and implications for immunotherapy.

Association between programmed cell death ligand 1 expression and thyroid cancer: A meta-analysis

BACKGROUND

Programmed cell death ligand 1 (PD-L1), which is highly expressed in a variety of malignant tumors, is closely related to clinicopathological features and prognosis. However, there are few studies on the potential effects of PD-L1 on thyroid carcinoma, the incidence of which has shown an upward trend worldwide. This study aimed to explore the association between PD-L1 expression and clinicopathological features and prognosis of thyroid cancer.

METHODS

An elaborate retrieval was performed using Medline, PubMed, Cochrane Library, EMBASE, Web of Science, WanFang databases, and China National Knowledge Infrastructure to determine the association between PD-L1 expression and disease-free survival (DFS), overall survival (OS), and clinicopathological features in patients with thyroid cancer. Study selection, data extraction, risk assessment, and data synthesis were performed independently by 2 reviewers. In this meta-analysis, RevMan 5.3 and Stata 15.1 were used for bias risk assessment and data synthesis.

RESULTS

After a detailed search, 2546 cases reported in 13 articles were included in this meta-analysis. The outcomes revealed that high expression of PD-L1 in patients with thyroid cancer was associated with poor DFS (hazard ratio [HR] = 3.37, 95% confidence interval [CI] 2.54-4.48, P < .00001) and OS (HR = 2.52, 95% CI: 1.20-5.32, P = .01). High PD-L1 expression was associated with tumor size ≥2 cm, tumor recurrence, extrathyroidal extension, concurrent thyroiditis, unifocal tumor, and absence of psammoma body (P < .05). Subgroup analysis showed that positive expression of PD-L1 was related to poor prognosis for DFS of non-medullary thyroid carcinoma, and the overexpression of PD-L1 in differentiated thyroid carcinoma (DTC) was related to tumor recurrence, concurrent thyroiditis, extrathyroidal extension, unifocal DTC, late stage DTC, and BRAFV600E mutation in DTC.

CONCLUSION

PD-L1 is a significant predictor of prognosis and malignancy of thyroid cancer (especially DTC), and PD-L1 inhibitors may be a promising therapeutic option for refractory thyroid cancer in the future.

Interleukin 6 regulates the expression of programmed cell death ligand 1 in thyroid cancer

Programmed cell death ligand 1 (PD‐L1), inducing T cell exhaustion to facilitate immune escape of tumor cells, is upregulated by interleukin 6 (IL‐6) in T cell lymphoma and ovarian cancer. The purpose of this study is to investigate the expression of IL‐6 and PD‐L1 in thyroid cancer, and whether IL‐6 regulates PD‐L1 expression. As a result, IL‐6 and PD‐L1 were highly expressed in thyroid cancer tissues. Multivariate logistic analysis showed that tumor size, distant metastasis, and risk stratification were significantly associated with IL‐6 expression (P < .05), and multifocality, lymph node metastasis, distant metastasis, risk stratification, and IL‐6 expression were identified as the independent predictors of PD‐L1 expression (P < .05). The invasiveness of thyroid cancer was significantly enhanced after IL‐6 treatment or PD‐L1 overexpression. PD‐L1 positive rate correlated with IL‐6 expression in cancer tissues (P < .001), and after IL‐6 treatment, the PD‐L1 expression in TPC‐1 and BCPAP significantly increased. The mitogen‐activated protein kinase pathway (MAPK) and the Janus‐activated kinase (JAK)–signal transducers and activators of transcription 3 (STAT3) signaling pathways were activated by IL‐6, and the IL‐6–induced PD‐L1 expression decreased after treatment with these two signaling pathway inhibitors. Knockdown of transcription factors c‐Jun and stat3 suppressed the expression of PD‐L1 induced by IL‐6, and these two factors could bind to PD‐L1 gene promoter directly and promote its transcription. It is concluded that IL‐6 and PD‐L1 are overexpressed in thyroid cancer and are related to tumor invasiveness. IL‐6 upregulates PD‐L1 expression through the MAPK and JAK‐STAT3 signaling pathways, which function via transcription factors c‐Jun and stat3.

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.

The Oncocytic Variant of Poorly Differentiated Thyroid Carcinoma Shows a Specific Immune-Related Gene Expression Profile

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) is a rare, follicular cell-derived neoplasm with an unfavorable prognosis. The oncocytic variant of PDTC may be associated with even more adverse outcome than classical PDTC cases, but its specific molecular features are largely unknown. Our aim was to explore the immune-related gene expression profile of oncocytic and classical PDTC, in correlation with clinical and pathological characteristics (including programmed death ligand 1 [PD-L1] expression) and outcome, and in comparison with a control group of well-differentiated follicular carcinomas (WDFCs), including conventional follicular carcinomas (FTCs) and Hürthle cell carcinomas (HCCs).

METHODS

A retrospective series of 48 PDTCs and 24 WDFCs was analyzed by means of NanoString technology employing the nCounter PanCancer Immune Profiling panel. Gene expression data were validated using quantitative real-time polymerase chain reaction.

RESULTS

Oncocytic PDTCs showed a specific immune-related gene expression profile, with higher expression of LAIR2, CD274, DEFB1, IRAK1, CAMP, LCN2, LY96, and APOE, and lower expression of NOD1, as compared to conventional PDTCs. This molecular signature was associated with increased intratumoral lymphocytic infiltration, PD-L1 expression, and adverse outcome. Three of these genes, CD274, DEFB1, and IRAK1, as well as PD-L1 expression, were also the hallmarks of HCCs as compared to FTCs. By contrast, the panel of genes differentially regulated in PDTCs as compared to WDFCs was unrelated to the oncocytic phenotype.

CONCLUSIONS

Our results revealed a distinctive immune-related gene expression profile of oncocytic PDTC and confirmed a more aggressive outcome in this cancer subtype. These findings may provide guidance when exploring novel immunotherapeutic options for oncocytic PDTC patients.

Immunotherapy for advanced thyroid cancers - rationale, current advances and future strategies

In the past decade, the field of cancer immunotherapy has been revolutionized by immune checkpoint blockade (ICB) technologies. Success across a broad spectrum of cancers has led to a paradigm shift in therapy for patients with advanced cancer. Early data are now accumulating in progressive thyroid cancers treated with single-agent ICB therapies and combination approaches that incorporate ICB technologies. This Review discusses our current knowledge of the immune response in thyroid cancers, the latest and ongoing immune-based approaches, and the future of immunotherapies in thyroid cancer. Physiologically relevant preclinical mouse models and human correlative research studies will inform development of the next stage of immune-based therapies for patients with advanced thyroid cancer.

Association of PD-L1 and IDO1 expression with JAK-STAT pathway activation in soft-tissue leiomyosarcoma

PURPOSE

Therapies targeting the immune checkpoint molecules programmed death ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO1) have been explored in various malignant tumours. In this study, we examined the relationship between PDL-1, IDO1 and JAK2 expression and the roles of these signal pathways in soft tissue leiomyosarcoma (LMS).

METHODS

The next-generation sequencing data of 53 patients with LMS were obtained from an online public database and were used to assess PD-L1, IDO1 and JAK2 gene amplification and mRNA expression. Then, we determined the relationship between JAK-STAT pathway activation and PD-L1 and IDO1 expression in a LMS cell line. In addition, immunohistochemical staining of 69 cases of LMS was performed for PD-L1, IDO1, TDO2 and phosphorylated JAK2 (pJAK2).

RESULTS

Comprehensive gene expression analysis using microarray and RNA-Seq data revealed that PD-L1 and IDO1 mRNA expression positively correlated with JAK2 and STAT1 mRNA expression. Two of the 53 cases exhibited PD-L1 and JAK2 gene amplification; however, they were not related to their gene expression. LMS cell line analysis revealed that IFN-γ supplementation induced IDO1 and PD-L1 expression; these effects were suppressed by JAK inhibition. Immunohistochemical analysis of the resected specimens revealed that TDO2 expression positively correlated with pJAK2 (P = 0.0490) and IDO1 expression (P < 0.0001). PD-L1-positive specimens tended to express pJAK2; however, the relationship did not reach statistical significance (P = 0.1477).

CONCLUSION

The results suggest the possible feasibility of the combined inhibition of PD-1/PD-L1 or IDO1 with IFN-γ-JAK-STAT pathway inhibition to treat soft tissue LMS.

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.

PD-L1 and IDO1 expression and tumor-infiltrating lymphocytes in osteosarcoma patients: comparative study of primary and metastatic lesions

PURPOSE

Programmed death ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO1) are immunosuppressive proteins known to be associated with poor prognosis in various cancers. However, their expression and clinical relevance in osteosarcoma remain unknown. In this study, the relationships of PD-L1 and IDO1 expression with clinicopathological features and prognosis were explored.

METHODS

The expression of PD-L1, IDO1, CD3, CD4, and CD8 in 112 formalin-fixed, paraffin-embedded tumor tissues collected by biopsy or surgical resection from 56 osteosarcoma patients was evaluated immunohistochemically. Moreover, four osteosarcoma cell lines were evaluated for the effects of IFNγ on PD-L1 and IDO1 mRNA expression by real-time reverse-transcription polymerase chain reaction.

RESULTS

In pre-neoadjuvant chemotherapy (NAC) primary specimens, 10 cases (17%) showed PD-L1 expression and 12 (21%) showed IDO1 expression. Six of ten cases (60%) with PD-L1 positivity co-expressed IDO1. In post-NAC metastatic lesions, the frequency of immunoexpression of PD-L1 and IDO1 was increased compared with that in pre-NAC specimens. PD-L1 and/or IDO1 expression was not associated with poor prognosis. PD-L1 immunoexpression was significantly associated with the infiltration of CD3⁺ T cells, CD4⁺ T cells, and CD8⁺ T cells; while, IDO1 immunoexpression was significantly associated with the infiltration of CD3⁺ T cells and CD4⁺ T cells. In all osteosarcoma cell lines, PD-L1 and IDO1 expression was upregulated by stimulation with IFNγ.

CONCLUSION

Our results suggest that the PD-L1 and IDO1 immune checkpoint inhibitors may provide clinical benefit in osteosarcoma patients with metastatic lesions after conventional chemotherapy.

High Expression of Interleukin-12A and Its Association with the Clinicopathology and Prognosis of Differentiated Thyroid Cancer

BACKGROUND

The inflammatory microenvironment is closely related to the occurrence and development of cancer. Members of the interleukin-12 (IL-12) cytokine family play synergistic or antagonistic roles in the tumor microenvironment, in the form of classic heterodimers or newly discovered monomers or homodimers.

OBJECTIVE

The purpose of this study was to investigate the association between IL-12A and the clinicopathology and prognosis of differentiated thyroid cancer (DTC).

METHODS

A total of 101 pathologically confirmed DTC patients were included in this study. Immunohistochemistry was performed to assess IL-12A expression in DTC and corresponding paracancerous tissues. The associations of IL-12A with clinicopathology and prognosis were evaluated.

RESULTS

IL-12A was expressed in both normal thyroid tissues and DTC, but its expression level was significantly higher in DTC than in normal thyroid tissues (p < 0.001). IL-12A was positively correlated with tumor size (p = 0.027), risk stratification (p = 0.020), and TNM (Tumor-Node-Metastasis) stage (p = 0.024), but not with age, sex, pathological type, multifocality, extrathyroid extension, lymph node metastasis, and distant metastasis (all p > 0.05). Lymphocytic thyroiditis was found in 26/101 patients (25.7%), which was negatively associated with IL-12A expression (p = 0.018). Multivariate logistic regression analysis showed that risk stratification was the significant independent predictor of IL-12A expression. The rate of disease persistence or recurrence (P&R) was 13/101 (12.9%), and a positive relationship was found between IL-12A expression and P&R (p = 0.020). Disease-free survival was affected by factors such as tumor size, extrathyroid extension, tumor stage (T stage), and IL-12A expression, with p values of 0.006, 0.048, 0.002, and 0.012, respectively. Multivariate Cox proportional-hazards analysis showed that tumor size ≥2 cm (hazard ratio [HR] = 4.041 [95% CI: 1.144-14.274], p = 0.031) and high IL-12A expression (HR = 4.027 [95% CI 1.014-15.994], p = 0.049) were independent predictors of prognosis of DTC patients.

CONCLUSIONS

IL-12A is highly expressed in DTC and is associated with disease aggressiveness. In addition, IL-12A is an independent predictor of the outcome of DTC.

New insight in endocrine-related adverse events associated to immune checkpoint blockade

Anticancer immunotherapy, in the form of immune checkpoint inhibition, is a paradigm shift that has transformed the care of patients with different types of solid and hematologic cancers. The most notable improvements have been seen in patients with melanoma, non-small-cell lung, bladder, renal, cervical, urotherial, and colorectal cancers, Merkel cell carcinoma, and Hodgkin lymphoma. Monoclonal antibodies (mAbs) targeting immune checkpoints (i.e., anti-CTLA: ipilimumab; anti-PD-1: nivolumab, pembrolizumab; anti-PD-L1: durvalumab, atezolizumab, avelumab) unleash the immune system against tumor cells targeting mainly T cells. Treatment with immune checkpoint inhibitors (ICIs) is associated with a variety of diverse and distinct immune-related adverse events (irAEs), reflecting the mechanistic underpinning of each target (i.e., CTLA-4, and PD-1/PD-L1 network). The most frequent endocrine irAEs associated with anti-PD-1 mAb treatment are thyroid dysfunctions, whereas hypophysitis is mostly linked to anti-CTLA-4 treatment. Type 1 diabetes mellitus and adrenalitis are rare irAEs. Combination therapy (anti-CTLA-4 plus anti-PD-1/PD-L1) can be associated with an increased risk and prevalence of endocrine irAEs. In this paper we discuss the pathophysiological and clinical aspects of irAEs with specific emphasis on endocrine irAEs associated with ICIs. With a growing number of patients treated with ICIs, a tight collaboration among oncologists, endocrinologists and immunologists appears necessary when the circumstances are more challenging and for better management of severe endocrine irAEs. Further investigations are urgently needed to better understand the mechanisms by which different ICIs can induce a variety of endocrine irAEs.

Molecular Alterations in Thyroid Cancer: From Bench to Clinical Practice

Thyroid cancer comprises different clinical and histological entities. Whereas differentiated (DTCs) malignancies are sensitive to radioiodine therapy, anaplastic (ATCs) and medullary (MTCs) tumors do not uptake radioactive iodine and display aggressive features associated with a poor prognosis. Moreover, in a majority of DTCs, disease evolution leads to the progressive loss of iodine sensitivity. Hence, iodine-refractory DTCs, along with ATCs and MTCs, require alternative treatments reflective of their different tumor biology. In the last decade, the molecular mechanisms promoting thyroid cancer development and progression have been extensively studied. This has led to a better understanding of the genomic landscape, displayed by thyroid malignancies, and to the identification of novel therapeutic targets. Indeed, several pharmacological compounds have been developed for iodine-refractory tumors, with four multi-target tyrosine kinase inhibitors already available for DTCs (sorafenib and lenvatinib) and MTCs (cabozantib and vandetanib), and a plethora of drugs currently being evaluated in clinical trials. In this review, we will describe the genomic alterations and biological processes intertwined with thyroid cancer development, also providing a thorough overview of targeted drugs already tested or under investigation for these tumors. Furthermore, given the existing preclinical evidence, we will briefly discuss the potential role of immunotherapy as an additional therapeutic strategy for the treatment of thyroid cancer.

PROGRAMMED CELL DEATH-LIGAND 1 OVEREXPRESSION IN THYROID CANCER

OBJECTIVE

Programmed cell death-ligand 1 (PD-L1) expression on tumor tissue has been associated with favorable response to anti-programmed cell death-receptor 1/PD-L1 therapy in many human cancers. Studies have reported that PD-L1 is also expressed in thyroid cancer. The objective of this paper is to introduce the potential predictive and therapeutic values of PD-L1 in thyroid cancer.

METHODS

A literature search was conducted in the PubMed database using the terms "PD-L1," "B7-H1," and "thyroid cancer." PD-L1 positivity was determined by immunohistochemical assay.

RESULTS

The frequency of PD-L1 positivity in different studies ranged from 6.1 to 82.5% in papillary thyroid cancer (PTC) patients and 22.2 to 81.2% in anaplastic thyroid cancer (ATC) patients. PD-L1 positivity rate was higher in ATC than in PTC within the same studies, and its expression intensity was significantly higher in tumor tissue than in the corresponding nontumor thyroid tissues. Moreover, PD-L1 expression was positively associated with the aggressiveness and recurrence of thyroid cancers and negatively associated with the differentiation status and outcomes. PD-L1 checkpoint pathway blockade may emerge as a promising therapeutic target in the treatment of thyroid cancers.

CONCLUSION

PD-L1 is a potential biomarker to predict the recurrence and prognosis of thyroid cancers. It is also a novel immunotherapy target for optimizing the management landscape of radioiodine-refractory and ATCs.

ABBREVIATIONS

ATC = anaplastic thyroid cancer; DTC = differentiated thyroid cancer; IHC = immunohistochemical; OS = overall survival; PD-1 = programmed cell death-receptor 1; PD-L1 = programmed cell death-ligand 1; PD-L2 = programmed cell death-ligand 2; PTC = papillary thyroid cancer; TNM = tumor-node-metastasis; Treg = regulatory T cell.

Blockade of the programmed death ligand 1 (PD-L1) as potential therapy for anaplastic thyroid cancer

PURPOSE

Anaplastic thyroid carcinoma (ATC) is a rare, highly aggressive form of thyroid cancer (TC) characterized by an aggressive behavior and poor prognosis, resulting in patients' death within a year. Standard treatments, such as chemo and radiotherapy, as well as tyrosine kinase inhibitors, are ineffective for ATC treatment. Cancer immunotherapy is one of the most promising research area in oncology. The PD-1/PD-L1 axis is of particular interest, in light of promising data showing a restoration of host immunity against tumors, with the prospect of long-lasting remissions.

METHODS

In this study, we evaluated PD-L1 expression in a large series of TCs (20 cases) showing a progressive dedifferentiation of the thyroid tumor from well differentiated TC to ATC, employing two different antibodies [R&D Systems and VENTANA PD-L1 (SP263) Rabbit Monoclonal Primary Antibody]. We also tested the anti PD-L1 mAb in an in vivo animal model.

RESULTS

We found that approximately 70-90% of ATC cases were positive for PD-L1 whereas normal thyroid and differentiated TC were negative. Moreover, all analyzed cases presented immunopositive staining in the endothelium of vessels within or in close proximity to the tumor, while normal thyroid vessels were negative. PD-L1 mAb was also effective in inhibiting ATC growth in an in vivo model.

CONCLUSIONS

These data suggest that immunotherapy may be a promising treatment specific for ATC suggesting the need to start with clinical TRIALs.

Differential expression of PD-L1 and IDO1 in association with the immune microenvironment in resected lung adenocarcinomas

Like programmed cell death ligand 1 (PD-L1), indoleamine 2,3-dioxygenase 1 (IDO1) is known to exert immunosuppressive effects and be variably expressed in human lung cancer. However, IDO1 expression has not been well studied in lung adenocarcinoma. PD-L1 and IDO1 expression was evaluated in 261 resected lung adenocarcinomas using tissue microarrays and H-scores (cutoff: 5). We compared IDO1 and PD-L1 expression with clinical features, tumor-infiltrating lymphocytes, HLA class I molecule expression, molecular alterations, and patient outcomes. There was expression of PD-L1 in 89 (34%) and IDO1 in 74 (29%) cases, with co-expression in 49 (19%). Both PD-L1 and IDO1 were significantly associated with smoking, aggressive pathologic features, and abundant CD8+ and T-bet+ (Th1 marker) tumor-infiltrating lymphocytes. PD-L1 expression was also associated with preserved HLA class I molecule expression (p = 0.002). Compared to PD-L1+/IDO1+ and PD-L1+ only cases, significantly fewer IDO1+ only cases had abundant CD8+ and T-bet+ tumor-infiltrating lymphocytes (p < 0.001, respectively). PD-L1 expression was significantly associated with EGFR wild-type (p < 0.001) and KRAS mutants (p = 0.021), whereas isolated IDO1 expression was significantly associated with EGFR mutations (p = 0.007). As for survival, PD-L1 was a significant predictor of decreased progression-free and overall survival by univariate but not multivariate analysis, while IDO1 was not associated with progression-free or overall survival. Interestingly, there was a significant difference in the 5-year progression-free and overall survival (p = 0.004 and 0.038, respectively), where cases without PD-L1 or IDO1 expression had the longest survival, and those with PD-L1 alone had the shortest survival. While PD-L1+/-IDO1 expression is observed in association with HLA class I expression, cytotoxic T lymphocyte/Th1 microenvironments, EGFR wild-type, and KRAS mutations, isolated IDO1 expression does not demonstrate these associations, suggesting that IDO1 may serve a distinct immunosuppressive role in lung adenocarcinomas. Thus, further investigation of IDO1 may demonstrate its role as a potential biomarker for patients who undergo anti-PD-1/PD-L1 therapy.

PD-1 Ligand Expression in Epithelial Thyroid Cancers: Potential Clinical Implications

The new immunotherapy targeting the programmed cell death 1 (PD-1) receptor and its cognate ligand PD-L1 has renewed hopes of eradicating the most difficult human cancers to treat. Among these, there are the poorly differentiated and anaplastic thyroid cancers, unresponsive to all the therapies currently in use. In the present review we will summarize information regarding the expression of PD-L1 in the different thyroid cancer histotypes, its correlation with clinicopathological features, and its potential prognostic value. Then, we will evaluate the available data indicating the PD-1/PD-L1 axis as a promising target for thyroid cancer therapy.

Indoleamine 2,3-dioxygenase 1 and Programmed Cell Death-ligand 1 Co-expression Predicts Poor Pathologic Response and Recurrence in Esophageal Squamous Cell Carcinoma after Neoadjuvant Chemoradiotherapy

This study aimed to investigate the impact of indoleamine 2,3-dioxygenase 1 (IDO1) expression, programmed cell death-ligand 1 (PD-L1) expression, CD8+ tumor-infiltrating lymphocyte (TIL) status, and their combination on pathologic complete response (pCR) and recurrence in esophageal squamous cell carcinoma (ESCC) treated with neoadjuvant chemoradiotherapy (CRT). Indoleamine 2,3-dioxygenase 1, PD-L1, and CD8+ TIL statuses were evaluated by immunohistochemical analysis on pre-CRT biopsies of 158 patients. Sixty-eight patients (43.0%) achieved pCR after neoadjuvant CRT and 48 patients (30.4%) developed recurrences after surgery. IDO1 and PD-L1 proteins were co-expressed in 28 patients (17.7%). Indoleamine 2,3-dioxygenase 1 positive patients showed a significantly lower pCR rate than IDO1 negative patients (28.6% vs. 51.0%, P = 0.007). Similarly, PD-L1 high expression was significantly negatively correlated with pCR rate (27.3% vs. 51.5%, P = 0.004). On multivariate analysis, IDO1 expression was an independent prognostic factor for developing recurrences. Stratification analysis revealed that patients with co-expression of IDO1 and PD-L1 were significantly associated with a lower pCR rate and worse recurrence-free survival than those with one or none positive protein. In conclusion, IDO1 and PD-L1 co-expression could predict poor pathologic response and high risk of recurrence in ESCC after neoadjuvant CRT, indicating a subset of patients who may benefit from CRT combined with immunotherapy.

Overexpression of Indoleamine 2,3-Dioxygenase 1 Promotes Epithelial-Mesenchymal Transition by Activation of the IL-6/STAT3/PD-L1 Pathway in Bladder Cancer

Indoleamine 2,3-dioxygenase 1 (IDO1) is a key enzyme in tryptophan metabolism and plays an important role in tumor cell immunosuppression and angiogenesis. The molecular mechanisms of IDO1 and epithelial-mesenchymal transition (EMT) have not been elucidated or studied in bladder cancer. Therefore, the aims of this study were to detect IDO1 expression in bladder cancer tissues and then to investigate the role of IDO1 in bladder cancer cell EMT and malignant phenotypes as well as the underlying molecular mechanisms. By immunohistochemistry, Western blot, and quantitative reverse transcription-polymerase chain reaction experiments, IDO1 was found to be overexpressed in bladder cancer tissues and cell lines compared to the noncancerous ones. In addition, knockdown of IDO1 expression was shown to inhibit bladder cancer cell growth, migration, invasion, and EMT. Furthermore, we demonstrated that IDO1 may promote EMT by activation of the interleukin 6/signal transducer and activator of transcription 3/programmed cell death ligand 1 signaling pathway. Collectively, these data suggest that IDO1 may play an important role in bladder cancer and may be a novel therapeutic target for patients with bladder cancer.

Papillary Thyroid Carcinoma Emerging from Hashimoto Thyroiditis Demonstrates Increased PD-L1 Expression, Which Persists with Metastasis

There is evidence that programmed death-ligand 1 (PD-L1) is expressed by thyroid follicular epithelium in thyroiditis, but the role of PD-L1 in papillary thyroid carcinoma (PTC) is poorly understood. We aimed to determine whether (1) the presence of background chronic lymphocytic thyroiditis (CLT) or Hashimoto thyroiditis (HT) influenced the expression of PD-L1 in benign follicular epithelium or in PTC and (2) if PD-L1 expression in PTC persisted with lymph node metastasis. We performed immunohistochemistry (IHC) for PD-L1 on formalin-fixed paraffin-embedded tissues. We first studied five cases of unremarkable thyroid, five cases of CLT, and five cases of HT without carcinoma. We subsequently performed PD-L1 IHC on ten cases of PTC arising in normal thyroid, ten cases of PTC arising in CLT, and ten cases of PTC arising in HT. Whenever available, we evaluated corresponding synchronous lymph node metastases from all cases for PD-L1 expression. PD-L1 expression was increased (10-90%) in all five cases of HT, only minimal expressed (1-5%) in two of five cases of CLT, and not expressed in five cases of unremarkable thyroid. PTC arising in normal thyroid or CLT nearly uniformly lacked PD-L1 expression. In contrast, PTC arising in HT demonstrated significant PD-L1 expression, which persisted in corresponding lymph node metastases. Background non-neoplastic follicular epithelium in the HT cases also demonstrated PD-L1 expression. Thyroid follicular epithelium in HT demonstrates increased PD-L1 expression, and PTC arising in a background of HT shows increased PD-L1 expression, which is retained with metastasis.