RAC1 Alterations Induce Acquired Dabrafenib Resistance in Association with Anaplastic Transformation in a Papillary Thyroid Cancer Patient

Anaplastic thyroid cancer: Genetic roles, targeted therapy, and immunotherapy

Anaplastic thyroid cancer (ATC) stands as the most formidable form of thyroid malignancy, presenting a persistent challenge in clinical management. Recent years have witnessed a gradual unveiling of the intricate genetic underpinnings governing ATC through next-generation sequencing. The emergence of this genetic landscape has paved the way for the exploration of targeted therapies and immunotherapies in clinical trials. Despite these strides, the precise mechanisms governing ATC pathogenesis and the identification of efficacious treatments demand further investigation. Our comprehensive review stems from an extensive literature search focusing on the genetic implications, notably the pivotal MAPK and PI3K-AKT-mTOR signaling pathways, along with targeted therapies and immunotherapies in ATC. Moreover, we screen and summarize the advances and challenges in the current diagnostic approaches for ATC, including the invasive tissue sampling represented by fine needle aspiration and core needle biopsy, immunohistochemistry, and 18F-fluorodeoxyglucose positron emission tomography/computed tomography. We also investigate enormous studies on the prognosis of ATC and outline independent prognostic factors for future clinical assessment and therapy for ATC. By synthesizing this literature, we aim to encapsulate the evolving landscape of ATC oncology, potentially shedding light on novel pathogenic mechanisms and avenues for therapeutic exploration.

RBM10 loss promotes metastases by aberrant splicing of cytoskeletal and extracellular matrix mRNAs

RBM10 modulates transcriptome-wide cassette exon splicing. Loss-of-function RBM10 mutations are enriched in thyroid cancers with distant metastases. Analysis of transcriptomes and genes mis-spliced by RBM10 loss showed pro-migratory and RHO/RAC signaling signatures. RBM10 loss increases cell velocity. Cytoskeletal and ECM transcripts subject to exon inclusion events included vinculin (VCL), tenascin C (TNC), and CD44. Knockdown of the VCL exon inclusion transcript in RBM10-null cells reduced cell velocity, whereas knockdown of TNC and CD44 exon inclusion isoforms reduced invasiveness. RAC1-GTP levels were increased in RBM10-null cells. Mouse HrasG12V/Rbm1OKO thyrocytes develop metastases that are reversed by RBM10 expression or by combined knockdown of VCL, CD44, and TNC inclusion isoforms. Thus, RBM10 loss generates exon inclusion in transcripts regulating ECM-cytoskeletal interactions, leading to RAC1 activation and metastatic competency. Moreover, a CRISPR-Cas9 screen for synthetic lethality with RBM10 loss identified NFκB effectors as central to viability, providing a therapeutic target for these lethal thyroid cancers.

Serum potassium level is associated with serum neurofilament light chain in American adult population: a cross-sectional analysis of the 2013-2014 National Health and Nutrition Examination Survey

Objective

Serum neurofilament light chain (sNfL) is one of the most sensitive diagnostic biomarkers for a variety of neurodegenerative pathologies. Potassium, an essential electrolyte, plays a critical role in maintaining neuronal health and the proper functioning of the central nervous system (CNS). The aim of our research was to investigate the association between serum potassium level and sNfL levels.

Methods

Based on the National Health and Nutrition Examination Survey (NHANES) database, we analyzed data from the 2013 to 2014 NHANES. Serum potassium concentrations were measured via ion-selective electrode (ISE) technology. The levels of sNfL were measured using a sensitive immunoassay developed by Siemens Healthineers. Our researcher analyzed the association between potassium level in serum and sNfL in American persons using multivariate logistic regression analysis and smoothed curve fitting. The consistency of these results was examined in various population subgroups.

Results

A total of 1,670 participants were involved in our research, including 872 women (50.5%) and 798 men (49.5%). The median serum potassium concentration was 4.0 mmol/L and the median sNfL was 12.3 pg/ml. After adjusting for potential confounders in the full model, individuals with higher serum potassium concentrations had higher sNfL levels (Q3 vs. Q1, β = 2.86, 95% CI: 0.33-5.39, P = 0.027). There was a non-linear positive dose-response association between higher serum potassium concentrations and sNfL levels (P for non-linearity = 0.028). Based on the results of stratified analysis, the relationship was stronger in the low- and middle-income group, non-drinking and non-physical activity participants, and participants with hypertension and diabetes.

Interpretation

In the cohort of American adults, a greater serum potassium concentration was linked to a higher sNfL. However, causality still needs to be further verified.

Role of the ETV5/p38 signaling axis in aggressive thyroid cancer cells

Patients with poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) face a much poorer prognosis than those with differentiated thyroid cancers. Around 25% of PDTCs and 35% of ATCs carry the BRAFV600E mutation, which constitutively activates the MAPK pathway, a key driver of cell growth. Although combining BRAF and MEK inhibitors can shrink tumors, resistance often develops. The exact cause of this resistance remains unclear. We previously found that in PDTC and ATC cells the BRAFV600E mutation is strongly linked to the expression of ETV5, a transcription factor downstream of the MAPK pathway. In the current study, we observed a significant association between ETV5 expression and the activation of p38, a central component of the MAPK14 pathway. Upon reduction of ETV5 levels, p38 expression and activation decreased, along with its upstream regulators MKK3/MKK6. This suggests that the MAPK and p38/MAPK14 pathways are interconnected and that p38 has oncogenic properties in these cancers. Using high-throughput screening, we established that combining p38 inhibitors with the BRAF inhibitor dabrafenib showed strong synergy in vitro, including in cells resistant to dabrafenib and trametinib that had acquired a secondary TP53 mutation. We then tested this combination in a genetically engineered mouse model (GEMM) of ATC. Overall, our findings suggest an oncogenic link between the MAPK and p38/MAPK14 pathways and that combining p38 pathway inhibitors with dabrafenib-targeted therapy could improve treatment outcomes for aggressive thyroid cancers. However, more specific and effective p38 inhibitors are required to fully harness this potential.

Genomic landscape and comparative analysis of tissue and liquid-based NGS in Taiwanese anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma (ATC) is an aggressive cancer that requirements rapid diagnosis and multimodal treatment. Next-generation sequencing (NGS) aids in personalized therapies and improved trial enrollment. The role of liquid-based NGS in ATC remains unclear. This study analyzed ATC samples using tissue-based NGS, liquid-based NGS, or both platforms. Genetic alterations showed highly heterogeneity, including mutations in RAS/RAF/MEK/ERK, PI3K/AKT/mTOR, cell cycle regulation, other receptor tyrosine kinases, DNA damage response, mismatch repair, and chromatin remodeling. TP53 (65.4%) and BRAF (30.8%) were the most frequently mutated genes in tissue NGS. In paired samples, the concordance rates were 69.2% for TP53 and 84.6% for BRAF. One of two patients treated with dabrafenib and trametinib showed a copy number gain in post-treatment tissue NGS, potentially indicating resistance. Liquid biopsy provides valuable supplementary information when tissue samples are insufficient. Further studies are necessary to understand resistance mechanisms and develop strategies to overcome them in BRAF-targeted therapy.

CTHRC1 is associated with BRAF(V600E) mutation and correlates with prognosis, immune cell infiltration, and drug resistance in colon cancer, thyroid cancer, and melanoma

Colon cancer, thyroid cancer, and melanoma are common malignant tumors that seriously threaten human health globally. The B-Raf proto-oncogene, serine/threonine kinase (BRAF)(V600E) mutation is an important driver gene mutation in these cancer types. In this study, we identified that collagen triple helix repeat containing 1 (CTHRC1) expression was associated with the BRAF(V600E) mutation in colon cancer, thyroid cancer, and melanoma. Based on database analysis and clinical tissue studies, CTHRC1 was verified to correlate with poor prognosis and worse clinicopathological features in colon cancer and thyroid cancer patients, but not in patients with melanoma. Several signaling pathways, immune cell infiltration, and immunotherapy markers were associated with CTHRC1 expression. Additionally, a high level of CTHRC1 was correlated with decreased sensitivity to antitumor drugs (vemurafenib, PLX-4720, dabrafenib, and SB-590885) targeting the BRAF(V600E) mutation. This study provides evidence of a significant correlation between CTHRC1 and the BRAF(V600E) mutation, suggesting its potential utility as a diagnostic and prognostic biomarker in human colon cancer, thyroid cancer, and melanoma.

Study on chemical profiling of bailing capsule and its potential mechanism against thyroiditis based on network pharmacology with molecular docking strategy

Bailing capsule (BLC), a drug that is clinically administered to modulate the autoimmune system, exhibits promising therapeutic potential in the treatment of thyroiditis. This study elucidates the chemical profile of BLC and its potential therapeutic mechanism in thyroiditis, leveraging network pharmacology and molecular docking techniques. Utilizing ultra-high-performance liquid chromatography coupled with linear trap-Orbitrap mass spectrometry (UHPLC-LTQ-Orbitrap MS), 58 compounds were identified, the majority of which were nucleosides and amino acids. Utilizing the ultra-high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UHPLC QqQ MS/MS) strategy, 16 representative active components from six batches of BLCs were simultaneously determined. Network pharmacology analysis further revealed that the active components included 5'-adenylate, guanosine, adenosine, cordycepin, inosine, 5'-guanylic acid, and l-lysine. Targets with higher connectivity included AKT1, MAPK3, RAC1, and PIK3CA. The signaling pathways primarily focused on thyroid hormone regulation and the Ras, PI3K/AKT, and MAPK pathways, all of which were intricately linked to inflammatory immunity and hormonal regulation. Molecular docking analysis corroborated the findings from network pharmacology, revealing that adenosine, guanosine, and cordycepin exhibited strong affinity toward AKT1, MAPK3, PIK3CA, and RAC1. Overall, this study successfully elucidated the material basis and preliminary mechanism underlying BLC's intervention in thyroiditis, thus laying a solid basis for further exploration of its in-depth mechanisms.

RBM10 loss induces aberrant splicing of cytoskeletal and extracellular matrix mRNAs and promotes metastatic fitness

RBM10 modulates transcriptome-wide cassette exon splicing. Loss-of-function RBM10 mutations are enriched in thyroid cancers with distant metastases. Analysis of transcriptomes and genes mis-spliced by RBM10 loss showed pro-migratory and RHO/RAC signaling signatures. RBM10 loss increases cell velocity. Cytoskeletal and ECM transcripts subject to exon-inclusion events included vinculin (VCL), tenascin C (TNC) and CD44. Knockdown of the VCL exon inclusion transcript in RBM10-null cells reduced cell velocity, whereas knockdown of TNC and CD44 exon-inclusion isoforms reduced invasiveness. RAC1-GTP levels were increased in RBM10-null cells. Mouse Hras G12V /Rbm1O KO thyrocytes develop metastases that are reversed by RBM10 or by combined knockdown of VCL, CD44 and TNC inclusion isoforms. Thus, RBM10 loss generates exon inclusions in transcripts regulating ECM-cytoskeletal interactions, leading to RAC1 activation and metastatic competency. Moreover, a CRISPR-Cas9 screen for synthetic lethality with RBM10 loss identified NFkB effectors as central to viability, providing a therapeutic target for these lethal thyroid cancers.

The Roles of RAC1 and RAC1B in Colorectal Cancer and Their Potential Contribution to Cetuximab Resistance

Colorectal cancer (CRC) is one of the most diagnosed cancers and a leading contributor to cancer-related deaths in the United States. Clinically, standard treatment regimens include surgery, radiation, and chemotherapy; however, there has been increasing development and clinical use of targeted therapies for CRC. Unfortunately, many patients develop resistance to these treatments. Cetuximab, the first targeted therapy approved to treat advanced CRC, is a monoclonal antibody that targets the epidermal growth factor receptor and inhibits downstream pathway activation to restrict tumor cell growth and proliferation. CRC resistance to cetuximab has been well studied, and common resistance mechanisms include constitutive signal transduction through downstream protein mutations and promotion of the epithelial-to-mesenchymal transition. While the most common resistance mechanisms are known, a proportion of patients develop resistance through unknown mechanisms. One protein predicted to contribute to therapy resistance is RAC1, a small GTPase that is involved in cytoskeleton rearrangement, cell migration, motility, and proliferation. RAC1 has also been shown to be overexpressed in CRC. Despite evidence that RAC1 and its alternative splice isoform RAC1B play important roles in CRC and the pathways known to contribute to cetuximab resistance, there is a need to directly study the relationship between RAC1 and RAC1B and cetuximab resistance. This review highlights the recent studies investigating RAC1 and RAC1B in the context of CRC and suggests that these proteins could play a role in resistance to cetuximab.

Emerging therapeutic options for follicular-derived thyroid cancer in the era of immunotherapy

Although most follicular-derived thyroid cancers are well differentiated and have an overall excellent prognosis following treatment with surgery and radioiodine, management of advanced thyroid cancers, including iodine refractory disease and poorly differentiated/undifferentiated subtypes, is more challenging. Over the past decade, better understanding of the genetic drivers and immune milieu of advanced thyroid cancers has led to significant progress in the management of these patients. Numerous targeted kinase inhibitors are now approved by the U.S Food and Drug administration (FDA) for the treatment of advanced, radioiodine refractory differentiated thyroid cancers (DTC) as well as anaplastic thyroid cancer (ATC). Immunotherapy has also been thoroughly studied and has shown promise in selected cases. In this review, we summarize the progress in the understanding of the genetic landscape and the cellular and molecular basis of radioiodine refractory-DTC and ATC, as well as discuss the current treatment options and future therapeutic avenues.

RET kinase inhibitors for the treatment of RET-altered thyroid cancers: Current knowledge and future directions

RET gain-of-function mutations are the most common drivers in medullary thyroid carcinoma, while RET fusions are identified in 5-10% of papillary thyroid carcinomas. Thus, RET plays a major role in the tumorigenesis of thyroid neoplasia, making it a valuable therapeutic target. Over a decade ago, multikinase inhibitors (MKIs) were first shown to have variable degrees of anti-RET activity. Despite some clinical efficacy in RET-altered thyroid cancers, significant off-target activity of MKIs led to marked toxicities limiting their use. More recently, two potent, highly selective RET inhibitors, selpercatinib and pralsetinib, were shown to have notable efficacy in RET-altered cancers, associated with more tolerable side effect profiles than those of MKIs. However, these treatments are non-curative, and emerging evidence suggests that patients who progress on therapy acquire mutations conferring drug resistance. Thus, the quest for a more definitive treatment for advanced, RET-altered thyroid cancers continues. This year we celebrate the 30th anniversary of the association of germline mutations of the RET proto-oncogene with the multiple endocrine neoplasia (MEN) type 2 syndromes. In this timely review, we summarize the current state-of-the-art treatment strategies for RET-altered thyroid cancers, their limitations, as well as future therapeutic avenues.

Machine-learning-based prediction of a diagnostic model using autophagy-related genes based on RNA sequencing for patients with papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer and belongs to the category of malignant tumors of the thyroid gland. Autophagy plays an important role in PTC. The purpose of this study is to develop a novel diagnostic model using autophagy-related genes (ARGs) in patients. In this study, RNA sequencing data of PTC samples and normal samples were obtained from GSE33630 and GSE29265. Then, we analyzed GSE33630 datasets and identified 127 DE-ARGs. Functional enrichment analysis suggested that 127 DE-ARGs were mainly enriched in pathways in cancer, protein processing in endoplasmic reticulum, toll-like receptor pathway, MAPK pathway, apoptosis, neurotrophin signaling pathway, and regulation of autophagy. Subsequently, CALCOCO2, DAPK1, and RAC1 among the 127 DE-ARGs were identified as diagnostic genes by support vector machine recursive feature elimination and least absolute shrinkage and selection operator algorithms. Then, we developed a novel diagnostic model using CALCOCO2, DAPK1, and RAC1 and its diagnostic value was confirmed in GSE29265 and our cohorts. Importantly, CALCOCO2 may be a critical regulator involved in immune microenvironment because its expression was related to many types of immune cells. Overall, we developed a novel diagnostic model using CALCOCO2, DAPK1, and RAC1 which can be used as diagnostic markers of PTC.

Single-cell RNA sequencing reveals the mechanism of PI3K/AKT/mTOR signaling pathway activation in lung adenocarcinoma by KRAS mutation

BACKGROUND

Aberrant activation of the phosphatidlinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway has been shown to play an important role in lung adenocarcinoma (LUAD). The effect of KRAS mutations, one of the important signatures of LUAD, on the PI3K/AKT/mTOR pathway in LUAD remains unclear.

METHODS

The Seurat package and principal component analysis were used for cell categorization of single-cell RNA sequencing data of LUAD. The AUCell score was used to assess the activity of the PI3K/AKT/mTOR pathway. Meanwhile, using the gene expression profiles and mutation profiles in the The Cancer Genome Atlas dataset, LUAD patients were categorized into KRAS-mutant (KRAS-MT) and KRAS-wild-types (KRAS-WT), and the corresponding enrichment scores were calculated using gene set enrichment analysis analysis. Finally, the subpopulation of cells with the highest pathway activity was identified, the copy number variation profile of this subpopulation was inscribed using the inferCNV package and the CMap database was utilized to make predictions for drugs targeting this subpopulation.

RESULTS

There is higher PI3K/AKT/mTOR pathway activity in LUAD epithelial cells with KRAS mutations, and high expression of KRAS, PIK3CA, AKT1 and PDPK1. In particular, we found significantly higher levels of pathway activity and associated gene expression in KRAS-MT than in KRAS-WT. We identified the highest pathway activity on a subpopulation of GRB2+ epithelial cells and the presence of amplified genes within its pathway. Finally, drugs were able to target GRB2+ epithelial cell subpopulations, such as wortmannin, palbociclib and angiogenesis inhibitor.

CONCLUSIONS

The present study provides a basic theory for the activation of the PI3K/AKT/mTOR signaling pathway as a result of KRAS mutations.

Recent advances in anaplastic thyroid cancer management

PURPOSE OF REVIEW

To summarize recent developments in the diagnosis and management of patients with anaplastic thyroid cancer (ATC).

RECENT FINDINGS

An updated edition of the Classification of Endocrine and Neuroendocrine Tumors was released by the World Health Organization (WHO), in which squamous cell carcinoma of the thyroid are now a subtype of ATC. Broader access to next generation sequencing has allowed better understanding of the molecular mechanisms driving ATC and improved prognostication. BRAF-targeted therapies revolutionized the treatment of advanced/metastatic BRAFV600E -mutated ATC, offering significant clinical benefit and allowing better locoregional control of disease through the neoadjuvant approach. However, inevitable development of resistance mechanisms represents a major challenge. Addition of immunotherapy to BRAF/MEK inhibition has shown very promising results and significant improvement in survival outcomes.

SUMMARY

Major advancements took place in the characterization and management of ATC in recent years, especially in patients with a BRAF V600E mutation. Still, no curative treatment is available, and options are limited once resistance to currently available BRAF-targeted therapies develops. Additionally, there is still a need for more effective treatments for patients without a BRAF mutation.

Co-amplification of CBX3 with EGFR or RAC1 in human cancers corroborated by a conserved genetic interaction among the genes

Chromobox Protein 3 (CBX3) overexpression is a common event occurring in cancer, promotes cancer cell proliferation and represents a poor prognosis marker in a plethora of human cancers. Here we describe that a wide spectrum of human cancers harbors a co-amplification of CBX3 gene with either EGFR or RAC1, which yields a statistically significant increase of both mRNA and protein levels of CBX3, EGFR and RAC1. We also reveal that the simultaneous overexpression of CBX3, RAC1 and EGFR gene products correlates with a worse prognosis compared to the condition when CBX3, RAC1 and EGFR are singularly upregulated. Furthermore, we also show that a co-occurrence of low-grade amplification, in addition to high-grade amplification, between CBX3 and EGFR or RAC1 is associated with a reduced patient lifespan. Finally, we find that CBX3 and RAC1/EGFR genetically interact in the model organism Drosophila melanogaster, suggesting that the simultaneous overexpression as well as well the co-occurrence of high- or low-grade copy number alterations in these genes is not accidental and could reflect evolutionarily conserved functional relationships.

Review article: new treatments for advanced differentiated thyroid cancers and potential mechanisms of drug resistance

The treatment of advanced, radioiodine refractory, differentiated thyroid cancers (RR-DTCs) has undergone major advancements in the last decade, causing a paradigm shift in the management and prognosis of these patients. Better understanding of the molecular drivers of tumorigenesis and access to next generation sequencing of tumors have led to the development and Food and Drug Administration (FDA)-approval of numerous targeted therapies for RR-DTCs, including antiangiogenic multikinase inhibitors, and more recently, fusion-specific kinase inhibitors such as RET inhibitors and NTRK inhibitors. BRAF + MEK inhibitors have also been approved for BRAF-mutated solid tumors and are routinely used in RR-DTCs in many centers. However, none of the currently available treatments are curative, and most patients will ultimately show progression. Current research efforts are therefore focused on identifying resistance mechanisms to tyrosine kinase inhibitors and ways to overcome them. Various novel treatment strategies are under investigation, including immunotherapy, redifferentiation therapy, and second-generation kinase inhibitors. In this review, we will discuss currently available drugs for advanced RR-DTCs, potential mechanisms of drug resistance and future therapeutic avenues.

Early Combined SHP2 Targeting Reverses the Therapeutic Resistance of Vemurafenib in Thyroid Cancer

The BRAFV600E mutation is the most common oncogenic mutation in thyroid cancer, suggesting an aggressive subtype of thyroid cancer and poor prognosis. Vemurafenib, a selective inhibitor of BRAFV600E, may provide therapeutic benefit in various cancers including thyroid cancer. However, the prevalence of drug resistance remains a challenge because of the feedback activation of the MAPK/ERK and PI3K/AKT pathways. In treating thyroid cancer cells with vemurafenib, we have detected reactivation of the MAPK/ERK signaling pathway as a result of the release of multiple receptor tyrosine kinases (RTKs) from the negative feedback of ERK phosphorylation. SHP2 is an important target protein downstream of the RTK signaling pathway. Decreasing it through SHP2 knockdown or the use of an inhibitor of SHP2 (SHP099) was found to significantly increase the early sensitivity and reverse the late resistance to vemurafenib in BRAFV600E mutant thyroid cancer cells. Overall, our findings suggest that blocking SHP2 reverses the reactivation of the MAPK/ERK signaling pathway caused by the activation of RTKs and improves the sensitivity of thyroid cancer to vemurafenib, which has potential implications for mechanism-based early combination strategies to treat thyroid cancer.

Anti-EGFR/BRAF-Tyrosine Kinase Inhibitors in Thyroid Carcinoma

Alterations in significant genes located on chromosome 7 - including epidermal growth factor receptor (EGFR) and also v-Raf murine sarcoma viral oncogene homolog B (BRAF) as a mitogen-activated protein kinase (MAPK)  - combined or not with numerical imbalances of the whole chromosome (aneuploidy-polysomy) are crucial genetic events involved in the development and progression of malignancies. Identification of EGFR/BRAF-dependent specific somatic mutations and other mechanisms of deregulation (i.e., amplification) is critical for applying targeted therapeutic approaches [tyrosine kinase inhibitors (TKIs] or monoclonal antibodies (mAbs). Thyroid carcinoma is a specific pathological entity characterized by a variety of histological sub-types. Follicular thyroid carcinoma (FTC), papillary thyroid carcinoma (PTC), medullary thyroid carcinoma (MTC), and anaplastic thyroid carcinoma (ATC) represent its main sub-types. In the current review, we explore the role of EGFR/BRAF alterations in thyroid carcinoma in conjunction with the corresponding anti-EGFR/BRAF TKI-based novel therapeutic strategies for patients with specific genetic signatures.

MAPK Pathway Inhibitors in Thyroid Cancer: Preclinical and Clinical Data

Thyroid cancer is the most common endocrine cancer, with a good prognosis in most cases. However, some cancers of follicular origin are metastatic or recurrent and eventually become radioiodine refractory thyroid cancers (RAIR-TC). These more aggressive cancers are a clinical concern for which the therapeutic arsenal remains limited. Molecular biology of these tumors has highlighted a hyper-activation of the Mitogen-Activated Protein Kinases (MAPK) pathway (RAS-RAF-MEK-ERK), mostly secondary to the BRAF^V600E hotspot mutation occurring in about 60% of papillary cancers and 45% of anaplastic cancers. Therapies targeting the different protagonists of this signaling pathway have been tested in preclinical and clinical models: first and second generation RAF inhibitors and MEK inhibitors. In clinical practice, dual therapies with a BRAF inhibitor and a MEK inhibitor are being recommended in anaplastic cancers with the BRAF^V600E mutation. Concerning RAIR-TC, these inhibitors can be used as anti-proliferative drugs, but their efficacy is inconsistent due to primary or secondary resistance. A specific therapeutic approach in thyroid cancers consists of performing a short-term treatment with these MAPK pathway inhibitors to evaluate their capacity to redifferentiate a refractory tumor, with the aim of retreating the patients by radioactive iodine therapy in case of re-expression of the sodium-iodide symporter (NIS). In this work, we report data from recent preclinical and clinical studies on the efficacy of MAPK pathway inhibitors and their resistance mechanisms. We will also report the different preclinical and clinical studies that have investigated the redifferentiation with these therapies.

Target therapy for BRAF mutated anaplastic thyroid cancer: a clinical and molecular study

OBJECTIVES

Anaplastic thyroid carcinoma (ATC) has a poor survival. The combination of Dabrafenib plus Trametinib (DT) had a significant impact in survival of BRAF p.V600E patients. However, durable responses may be compromised by resistance. We aim to present our experience with DT in BRAF positive ATC patients and compare the outcomes with usual therapy, and to study tumor molecular alterations in the DT group.

METHODS

Patients treated between May 2018 and April 2022 in a tertiary referral center, assessed for BRAF status were included. Patients were divided in three groups: BRAF p.V600E treated with DT, BRAF wild type (WT) under multimodal therapy (MT), and BRAF WT under compassionate care (CC). Response was assessed monthly in the first 6 months and every 3 months afterwards, by RECIST 1.1. Overall survival (OS) and progression-free survival (PFS) were estimated with the Kaplan-Meier method and compared with the log-rank test.

RESULTS

Twenty-seven ATC patients were included (DT = 9, MT = 8, and CC = 10). Median OS was 475 days for DT, 156 days for MT, and 39 days for CC (P < .001). At 12 months, only patients in the DT group were alive (71%). Median PFS was 270 days, in the DT group, compared with less than 32 days in BRAF WT (P < .001). No severe adverse events were reported. Molecular profiling showed that in one of the four clinical progressions, a pathogenic NRAS mutation was found.

CONCLUSIONS

Our results show a significant real-world efficacy of Dabrafenib plus Trametinib in both survival and recurrence compared with standard treatment, with a good safety profile.

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.

Molecular mechanisms of resistance to kinase inhibitors and redifferentiation in thyroid cancers

Protein kinases play critical roles in cell survival, proliferation, and motility. Their dysregulation is therefore a common feature in the pathogenesis of a number of solid tumors, including thyroid cancers. Inhibiting activated protein kinases has revolutionized thyroid cancer therapy, offering a promising strategy in treating tumors refractory to radioactive iodine treatment or cytotoxic chemotherapies. However, despite satisfactory early responses, these drugs are not curative and most patients inevitably progress due to drug resistance. This review summarizes up-to-date knowledge on various mechanisms that thyroid cancer cells develop to bypass protein kinase inhibition and outlines strategies that are being explored to overcome drug resistance. Understanding how cancer cells respond to drugs and identifying novel molecular targets for therapy still represents a major challenge for the treatment of these patients.

Dabrafenib Versus Dabrafenib + Trametinib in BRAF-Mutated Radioactive Iodine Refractory Differentiated Thyroid Cancer: Results of a Randomized, Phase 2, Open-Label Multicenter Trial

Background: Oncogenic BRAF mutations are commonly found in advanced differentiated thyroid cancer (DTC), and reports have shown efficacy of BRAF inhibitors in these tumors. We investigated the difference in response between dabrafenib monotherapy and dabrafenib + trametinib therapy in patients with BRAF-mutated radioactive iodine refractory DTC. Methods: In this open-label randomized phase 2 multicenter trial, patients aged ≥18 years with BRAF-mutated radioactive iodine refractory DTC with progressive disease by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 within 13 months before enrollment were eligible. Patients were randomly assigned to receive dabrafenib alone or dabrafenib + trametinib. The primary endpoint was objective response rate by modified RECIST (minor response of -20% to -29%, partial and complete response) within the first 24 weeks of therapy. Trial Registration Number: NCT01723202. Results: A total of 53 patients were enrolled. The objective response rate (modified RECIST) was 42% (11/26 [95% confidence interval {CI} 23-63%]) with dabrafenib versus 48% (13/27 [CI 29-68%]) with dabrafenib + trametinib (p = 0.67). Objective response rate (RECIST 1.1) was 35% (9/26 [CI 17-56%]) with dabrafenib and 30% (8/27 [CI 14-51%]) with dabrafenib + trametinib. Most common treatment-related adverse events included skin and subcutaneous tissue disorders (17/26, 65%), fever (13/26, 50%), hyperglycemia (12/26, 46%) with dabrafenib alone and fever (16/27, 59%), nausea, chills, fatigue (14/27, 52% each) with dabrafenib + trametinib. There were no treatment-related deaths. Conclusions: Combination dabrafenib + trametinib was not superior in efficacy compared to dabrafenib monotherapy in patients with BRAF-mutated radioiodine refractory progressive DTC.

Advances in Thyroid Carcinoma

"Thyroid cancer" encompasses a heterogeneous group of tumors that range from the predominant papillary thyroid cancer (PTC) subtype, which shows excellent survival rates, to the poorly differentiated (PDTC) and anaplastic thyroid cancer (ATC) forms, accounting for most of the disease-related morbidity and mortality [...].