Molecular basis and targeted therapies for radioiodine refractory thyroid cancer

Circulating Biomarkers of Thyroid Cancer: An Appraisal

Thyroid cancer is the most prevalent endocrine cancer. The prognosis depends on the type and stage at diagnosis. Thyroid cancer treatments involve surgery, possibly followed by additional therapeutic options such as hormone therapy, radiation therapy, targeted therapy and chemotherapy. Besides the well-known thyroid tumor biomarkers, new circulating biomarkers are now emerging. Advances in genomic, transcriptomic and proteomic technologies have allowed the development of novel tumor biomarkers. This review explores the current literature data to critically analyze the benefits and limitations of routinely measured circulating biomarkers for the diagnosis and monitoring of thyroid cancer. The review also sheds light on new circulating biomarkers, focusing on the challenges of their use in the clinical management of thyroid cancer, underlining the need for the identification of a new generation of circulating biomarkers.

Pathogenesis and Management Strategies in Radioiodine-Refractory Differentiated Thyroid Cancer: From Molecular Mechanisms Toward Therapeutic Approaches: A Comprehensive Review

Thyroid cancer (TC) remains the most common cancer in endocrinology. Differentiated thyroid cancer (DTC), the most common type of TC, generally has a favorable outlook with conventional treatment, which typically includes surgery along with radioiodine (RAI) therapy and thyroid-stimulating hormone (TSH) suppression through thyroid hormone therapy. However, a small subset of patients (less than 5%) develop resistance to RAI. This resistance occurs due to the loss of Na/I symporter (NIS) activity, which is crucial for iodine absorption in thyroid cells. The decline in NIS activity appears to be due to gene modifications, reconfigurations with irregular stimulation of signaling pathways such as MAPK and PI3K/Akt pathways. These molecular changes lead to a diminished ability of DTC cells to concentrate iodine, which makes RAI therapy ineffective. As a consequence, patients with radioiodine-refractory DTC require alternative treatments. Therapy with tyrosine kinase inhibitors (TKIs) has emerged as the primary treatment option to inhibit proliferation and growth of RAIR-DTC, targeting the pathways responsible for tumor progression. In this article, we analyze molecular processes responsible for RAI resistance and explore both conventional and emerging therapeutic strategies for managing RAIR-DTC, aiming to improve patient outcomes.

No Correlation between PD-L1 and NIS Expression in Lymph Node Metastatic Papillary Thyroid Carcinoma

Approximately 90% of thyroid cancers are differentiated thyroid cancers (DTCs), originating from follicular epithelial cells. Out of these, 90% are papillary thyroid cancer (PTC), and 10% are follicular thyroid cancer (FTC). The standard care procedure for PTC includes surgery, followed by radioiodine (RAI) ablation and thyroid-stimulating hormone (TSH) suppressive therapy. Globally, treating radioiodine-refractory DTC poses a challenge. During malignant transformation, thyroid epithelial cells often lose their ability to absorb radioiodine due to impaired membrane targeting or lack of NIS (sodium/iodide symporter) expression. Recent reports show an increase in PD-L1 (programmed death ligand 1) expression in thyroid cancer cells during dedifferentiation. However, no research exists wherein NIS and PD-L1 expression are analyzed together in thyroid cancer. Therefore, we aimed to investigate and correlate PD-L1 and NIS expression within primary tumor samples of lymph node metastatic PTC. We analyzed the expression of hNIS (human sodium/iodide symporter) and PD-L1 in primary tumor samples from metastatic PTC patients using immunohistochemistry. Immunohistochemistry analysis of PD-L1 and NIS was conducted in 89 and 86 PTC cases, respectively. Any subcellular NIS localization was counted as a positive result. PD-L1 expression was absent in 25 tumors, while 58 tumors displayed PD-L1 expression in 1-50% of their cells; in 6 tumors, over 50% of the cells tested positive for PD-L1. NIS immunohistochemistry was performed for 86 primary papillary carcinomas, with 51 out of 86 tumors showcasing NIS expression. Only in seven cases was NIS localized in the plasma membrane; in most tumors, NIS was primarily found in the intracytoplasmic membrane compartments. In the case of PD-L1 staining, cells showing linear membrane positivity of any intensity were counted as positive. The evaluation of NIS immunostaining was simpler: cells showing staining of any intensity of cytoplasmic or membranous fashion were counted as positive. The number of NIS positive cells can be further divided into cytoplasmic and membrane positive compartments. There was no observed correlation between PD-L1 and NIS expression. We can speculate that the manipulation of the PD-1/PD-L1 axis using anti-PD-L1 or anti-PD-1 antibodies could reinstate the functional expression of NIS. However, based on our study, the only conclusion that can be drawn is that there is no correlation between the percentage of NIS- or PD-L1-expressing tumor cells in the primary tumor of lymph node metastatic PTC.

Clinicopathological features of differentiated thyroid carcinoma as predictors of the effects of radioactive iodine therapy

BACKGROUND

Patients with differentiated thyroid cancer (DTC) usually have an excellent prognosis; however, 5 %-15 % develop radioactive iodine-refractory (RAIR) DTC (RAIR-DTC), which has a poor prognosis and limited treatment options. The aim of the present study was to investigate the clinicopathological characteristics of RAIR-DTC in order to provide clinical evidence for timely prediction of the effects of iodine therapy.

METHODS

Clinicopathological data for 44 patients with RAIR-DTC and 50 patients with radioiodine-avid DTC (RAIA-DTC) were retrospectively analyzed. The risk factors for RAIR-DTC were evaluated and a RAIR-DTC prediction model was established.

RESULTS

RAIR-DTC showed unique clinicopathological features that differed from those of RAIA-DTC; these included age >55 years, a high-risk histological subtype, a large tumor size, a late TNM stage, calcification, distant metastasis, and more than six metastatic lymph nodes. Patients with RAIR-DTC also developed earlier tumor progression. Binary logistic regression analysis showed that distant metastasis, a high-risk histological subtype, and a maximum tumor diameter of ≥12.5 mm were independent risk factors for RAIR-DTC, and the specificity and sensitivity of a combination of these three parameters for the prediction of RAIR-DTC were 98.0 % and 56.8 %, respectively. Decision curve analysis and the calibration curve revealed that the combined prediction of these three parameters had good repeatability and accuracy.

CONCLUSION

The clinicopathological features of DTC can effectively predict the effects of iodine therapy. A combination of distant metastasis, a high-risk histological subtype, and a maximum tumor diameter of ≥12.5 mm showed significantly higher prediction accuracy.

Advances in targeted therapy and biomarker research in thyroid cancer

Driven by the intricacy of the illness and the need for individualized treatments, targeted therapy and biomarker research in thyroid cancer represent an important frontier in oncology. The variety of genetic changes associated with thyroid cancer demand more investigation to elucidate molecular details. This research is clinically significant since it can be used to develop customized treatment plans. A more focused approach is provided by targeted therapies, which target certain molecular targets such as mutant BRAF or RET proteins. This strategy minimizes collateral harm to healthy tissues and may also reduce adverse effects. Simultaneously, patient categorization based on molecular profiles is made possible by biomarker exploration, which allows for customized therapy regimens and maximizes therapeutic results. The benefits of targeted therapy and biomarker research go beyond their immediate clinical impact to encompass the whole cancer landscape. Comprehending the genetic underpinnings of thyroid cancer facilitates the creation of novel treatments that specifically target aberrant molecules. This advances the treatment of thyroid cancer and advances precision medicine, paving the way for the treatment of other cancers. Taken simply, more study on thyroid cancer is promising for better patient care. The concepts discovered during this investigation have the potential to completely transform the way that care is provided, bringing in a new era of personalized, precision medicine. This paradigm shift could improve the prognosis and quality of life for individuals with thyroid cancer and act as an inspiration for advances in other cancer types.