Littérature scientifique sur le sujet « Targeted therapies, RAS, MEK, PI3K »

Abstract Hyperactivated Ras-pathways serve as oncogenic drivers in multiple human tumors including acute myelogenous leukemia (AML) (Ahearn et al. Nat Rev Mol Cell Biol 2011). The specific functions of these pathways in AML are unclear, thwarting the rational application of targeted therapeutics. Recently, we have shown that NRASG12V–activated signaling pathways are critical to leukemia stem cell maintenance (Sachs et al. submitted). To elucidate which Ras-activated signaling molecules mediate self-renewal in AML, we employed a murine model that harbors Mll-AF9 and a tetracycline repressible, activated NRAS (NRASG12V) and develops AML (Kim et al. Blood 2009). Primary leukemia cells were treated with therapeutic agents targeting Ras-activated signaling pathways. We used PD325901 to inhibit the Mek-Erk pathway, GDC0941 to inhibit the Pi3k pathway, and RAD001 to inhibit the mTor pathway. Using MTS assays, we identified the IC50 dose for each of these agents. Inhibitor-treated leukemia cells were submitted for RNA sequencing in order to investigate the effects of these agents on leukemia gene expression. Previously, we identified a list of NRASG12V responsive genes in our model. In these studies, we identified that PD325901-treatment most closely recapitulates the effect of NRASG12V inhibition on this comprehensive list of RAS-responsive genes. However, when we study the effects of these inhibitors on the subset of RAS-responsive genes that mediate leukemia self-renewal, we find that both PD325901 and RAD001 independently recapitulate the effects of NRASG12V withdrawal on this subset of genes implicating the Mek and mTor pathways in leukemia self renewal. Next, we treated primary leukemia cells with the IC50 dose of each drug and plated them in colony forming assays. We found that Mek or mTor inhibition, but not Pi3k inhibition, abrogated secondary colony formation corroborating our gene expression analyses and showing that, at doses that have equivalent effects on cell growth, only the Mek and mTor pathways are important for leukemia cell stem cell maintenance. These studies provide potential targets for leukemia stem cell-specific therapies. Disclosures: Sachs: Silicon Valley Biosystems: Consultancy. Bendall:DVS Sciences: Consultancy. Nolan:SAB for DVS Sciences and Nodality: Chairman Other; Cell Signalling Technologies and Becton Dickenson, Inc: Consultancy. Largaespada:Discovery Genomics, Inc: Consultancy, Share Holder Other; NeoClone Biotechnology, Inc: Consultancy, Share Holder, Share Holder Other.

Abstract Juvenile and chronic myelomonocytic leukemias (JMML and CMML) are aggressive myeloid malignancies categorized as myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN). Chemotherapy has little benefit for MDS/MPN patients, and new therapies are needed. We have used mouse models investigate the potential of signal transduction inhibitors in MDS/MPN, as JMML and CMML are associated with mutations in NRAS, KRAS, PTPN11, CBL, or NF1 that activate Ras signaling. Conditional Mx1-Cre, KrasLSL-D12 (designated KrasD12) mice develop an aggressive and fully penetrant MDS/MPN characterized by leukocytosis, splenomegaly, anemia, and death by 10-16 weeks of age. Mx1-Cre, Nf1flox/- mice (hereafter Nf1Δ/-) undergo conditional loss of Nf1. These mice also develop MDS/MPN, but the disease is more indolent. We and others have investigated inhibition of effector networks downstream of Ras, such as the Raf/MEK/ERK (MAPK) and phosphotidylinositol-3 kinase (PI3K)/Akt pathways. We previously showed that the MEK inhibitor PD0325901 induced sustained hematologic improvement in both KrasD12 and Nf1Δ/- mice. We also have reported that the class I PI3K inhibitor GDC-0941 improves hematologic function and prolongs survival in KrasD12 mice. However, GDC-0941 and other PI3K inhibitors attenuate both PI3K/Akt and Raf/MEK/ERK pathways due to effects of PI3K upstream of Ras. Therefore, the benefit from GDC-0941 could have been due to its modulation of Raf/MEK/ERK signaling. Here, we specifically test the importance of Akt signaling in MDS/MPN in KrasD12 and Nf1 mouse models using the allosteric inhibitor MK-2206. This compound binds to the interface of the PH and kinase domains of Akt1, Akt2, and Akt3, and does not inhibit any of 250 other kinases at 1 µM. MK-2206 induced substantial improvement in both KrasD12 and Nf1Δ/- mice. Mice treated with MK-2206 had pronounced reduction in leukocytosis, reticulocytosis and splenomegaly, increased hemoglobin concentration, and prolonged survival. MK-2206 had no hematologic effects in control WT mice, indicating some selectivity against aberrant hematopoiesis. Importantly, MK-2206 inhibited Akt but not Raf/MEK/ERK or Jak/STAT signaling. This demonstrates that canonical PI3K/Akt signaling plays an important role in Ras-driven MDS/MPN. Furthermore, combined inhibition of MEK and Akt with PD0325901+MK-2206 yielded a greater improvement in splenomegaly than either agent alone in both KrasD12 and Nf1Δ/- models. Akt has multiple effectors relevant to hematopoiesis and leukemia. Of these, mTOR is of particular interest for targeted cancer therapy. Therefore, we tested the response of KrasD12 mice to rapamycin, a partial inhibitor of mTOR with preferential activity against the mTORC1 complex. KrasD12 mice demonstrated variable responses to rapamycin, with approximately half undergoing a complete and durable hematologic response and the remainder having no response. Together, these studies further implicate PI3K/Akt signaling as a pathogenic effector downstream of Ras in MDS/MPN and support the idea that inhibitors targeting this pathway may have a role in treatment of JMML or CMML. Disclosures No relevant conflicts of interest to declare.

The few therapeutic strategies for advance hepatocellular carcinoma (HCC) on poor knowledge of its biology. For several years, sorafenib, a tyrosine kinase inhibitors (TKI) inhibitor, has been the approved treatment option, to date, for advanced HCC patients. Its activity is the inhibition of the retrovirus-associated DNA sequences protein (RAS)/Rapidly Accelerated Fibrosarcoma protein (RAF)/mitogen-activated and extracellular-signal regulated kinase (MEK)/extracellular-signal regulated kinases (ERK) signaling pathway. However, the efficacy of sorafenib is limited by the development of drug resistance, and the major neuronal isoform of RAF, BRAF and MEK pathways play a critical and central role in HCC escape from TKIs activity. Advanced HCC patients with a BRAF mutation display a multifocal and/or more aggressive behavior with resistance to TKI. Moreover, also long non-coding RNA (lnc-RNA) have been studied in epigenetic studies for BRAF aggressiveness in HCC. So far, lnc-RNA of BRAF could be another mechanism of cancer proliferation and TKI escape in HCC and the inhibition could become a possible strategy treatment for HCC. Moreover, recent preclinical studies and clinical trials evidence that combined treatments, involving alternative pathways, have an important role of therapy for HCC and they could bypass resistance to the following TKIs: MEK, ERKs/ribosomal protein S6 kinase 2 (RSK2), and phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR). These initial data must be confirmed in clinical studies, which are currently ongoing. Translational research discoveries could create new strategies of targeted therapy combinations, including BRAF pathway, and they could eventually bring light in new treatment of HCC.

Vestibular schwannoma (VS) is a benign tumor that originates from Schwann cells in the vestibular component. Surgical treatment for VS has gradually declined over the past few decades, especially for small tumors. Gamma knife radiosurgery has become an accepted treatment for VS, with a high rate of tumor control. For neurofibromatosis type 2 (NF2)-associated VS resistant to radiotherapy, vascular endothelial growth factor (VEGF)-A/VEGF receptor (VEGFR)-targeted therapy (e.g., bevacizumab) may become the first-line therapy. Recently, a clinical trial using a VEGFR1/2 peptide vaccine was also conducted in patients with progressive NF2-associated schwannomas, which was the first immunotherapeutic approach for NF2 patients. Targeted therapies for the gene product of SH3PXD2A-HTRA1 fusion may be effective for sporadic VS. Several protein kinase inhibitors could be supportive to prevent tumor progression because merlin inhibits signaling by tyrosine receptor kinases and the activation of downstream pathways, including the Ras/Raf/MEK/ERK and PI3K/Akt/mTORC1 pathways. Tumor-microenvironment-targeted therapy may be supportive for the mainstays of management. The tumor-associated macrophage is the major component of immunosuppressive cells in schwannomas. Here, we present a critical overview of targeted therapies for VS. Multimodal therapy is required to manage patients with refractory VS.

Malignant melanoma is the most aggressive type of skin cancer with invasive growth patterns. In 2021, 106,110 patients are projected to be diagnosed with melanoma, out of which 7180 are expected to die. Traditional methods like surgery, radiation therapy, and chemotherapy are not effective in the treatment of metastatic and advanced melanoma. Recent approaches to treat melanoma have focused on biomarkers that play significant roles in cell growth, proliferation, migration, and survival. Several FDA-approved molecular targeted therapies such as tyrosine kinase inhibitors (TKIs) have been developed against genetic biomarkers whose overexpression is implicated in tumorigenesis. The use of targeted therapies as an alternative or supplement to immunotherapy has revolutionized the management of metastatic melanoma. Although this treatment strategy is more efficacious and less toxic in comparison to traditional therapies, targeted therapies are less effective after prolonged treatment due to acquired resistance caused by mutations and activation of alternative mechanisms in melanoma tumors. Recent studies focus on understanding the mechanisms of acquired resistance to these current therapies. Further research is needed for the development of better approaches to improve prognosis in melanoma patients. In this article, various melanoma biomarkers including BRAF, MEK, RAS, c-KIT, VEGFR, c-MET and PI3K are described, and their potential mechanisms for drug resistance are discussed.

One of the biggest challenges in neuro-oncology is understanding the complexity of central nervous system tumors, such as gliomas, in order to develop suitable therapeutics. Conventional therapies in malignant gliomas reconcile surgery and radiotherapy with the use of chemotherapeutic options such as temozolomide, chloroethyl nitrosoureas and the combination therapy of procarbazine, lomustine and vincristine. With the unraveling of deregulated cancer cell signaling pathways, targeted therapies have been developed. The most affected signaling pathways in glioma cells involve tyrosine kinase receptors and their downstream pathways, such as the phosphatidylinositol 3-kinases (PI3K/AKT/mTOR) and mitogen-activated protein kinase pathways (MAPK). MAPK pathway inhibitors include farnesyl transferase inhibitors, Ras kinase inhibitors and mitogen-activated protein extracellular regulated kinase (MEK) inhibitors, while PI3K/AKT/mTOR pathway inhibitors are divided into pan-inhibitors, PI3K/mTOR dual inhibitors and AKT inhibitors. The relevance of the immune system in carcinogenesis has led to the development of immunotherapy, through vaccination, blocking of immune checkpoints, oncolytic viruses, and adoptive immunotherapy using chimeric antigen receptor T cells. In this article we provide a comprehensive review of the signaling pathways underlying malignant transformation, the therapies currently used in the treatment of malignant gliomas and further explore therapies under development, including several ongoing clinical trials.

The common mutation BRAFV600 in primary melanomas activates the mitogen-activated protein kinase/extracellular-signal-regulated kinase (MAPK/ERK) pathway and the introduction of proto-oncogene B-Raf (BRAF) and mitogen-activated protein kinase kinase (MEK) inhibitors (BRAFi and MEKi) was a breakthrough in the treatment of these cancers. However, 15–20% of tumors harbor primary resistance to this therapy, and moreover, patients develop acquired resistance to treatment. Understanding the molecular phenomena behind resistance to BRAFi/MEKis is indispensable in order to develop novel targeted therapies. Most often, resistance develops due to either the reactivation of the MAPK/ERK pathway or the activation of alternative kinase signaling pathways including phosphatase and tensin homolog (PTEN), neurofibromin 1 (NF-1) or RAS signaling. The hyperactivation of tyrosine kinase receptors, such as the receptor of the platelet-derived growth factor β (PDFRβ), insulin-like growth factor 1 receptor (IGF-1R) and the receptor for hepatocyte growth factor (HGF), lead to the induction of the AKT/3-phosphoinositol kinase (PI3K) pathway. Another pathway resulting in BRAFi/MEKi resistance is the hyperactivation of epidermal growth factor receptor (EGFR) signaling or the deregulation of microphthalmia-associated transcription factor (MITF).

Melanoma possesses invasive metastatic growth patterns and is one of the most aggressive types of skin cancer. In 2021, it is estimated that 7180 deaths were attributed to melanoma in the United States alone. Once melanoma metastasizes, traditional therapies are no longer effective. Instead, immunotherapies, such as ipilimumab, pembrolizumab, and nivolumab, are the treatment options for malignant melanoma. Several biomarkers involved in tumorigenesis have been identified as potential targets for molecularly targeted melanoma therapy, such as tyrosine kinase inhibitors (TKIs). Unfortunately, melanoma quickly acquires resistance to these molecularly targeted therapies. To bypass resistance, combination treatment with immunotherapies and single or multiple TKIs have been employed and have been shown to improve the prognosis of melanoma patients compared to monotherapy. This review discusses several combination therapies that target melanoma biomarkers, such as BRAF, MEK, RAS, c-KIT, VEGFR, c-MET and PI3K. Several of these regimens are already FDA-approved for treating metastatic melanoma, while others are still in clinical trials. Continued research into the causes of resistance and factors influencing the efficacy of these combination treatments, such as specific mutations in oncogenic proteins, may further improve the effectiveness of combination therapies, providing a better prognosis for melanoma patients.

11514 Background: Contemporary chemotherapy-based regimens provide cures for most pediatric & AYA cancers. However, for patients with relapsed/refractory malignancies, outcomes are poor & imply a distinct and aggressive biology. Identifying common themes in the molecular architecture & oncogenic mechanisms in these patients is a critical priority for drug development. We hypothesized that the molecular signature of cancers in these patients would be independent of histology. We also assessed the response to molecular alteration (MA)-targeted therapies. Methods: IRB-approved analysis of MAs in 306 relapsed/refractory pediatric & AYA malignancies (116 hematologic malignancies, 68 sarcomas, 46 neuroblastomas, 36 CNS, 14 liver, 9 renal, 17 other) was performed. DNA was analyzed for MAs (Foundation Medicine, Cambridge, MA; Univ of Washington, Seattle, WA); additional MAs were identified by cytogenetic & fluorescent in situ hybridization analyses. Results: Median age was 8 years (range birth - 44 yrs). MAs were identified in 90.1% of patients & included a median of 2 mutations (range 0-18) in 133 cancer-related genes. In contrast to genomic analyses of de novo malignancies in children, a high frequency of TP53 MAs was identified (20.4% of patients) and was associated with inferior survival. MAs were identified in targetable pathways including cell cycle regulation (32.6%), DNA repair (7.2%), epigenetic (28.6%), RAS/RAF/MEK (24%), tyrosine kinase (TK; 18.4%), PI3K/AKT/mTOR (11.8%), and NOTCH/WNT (8.9%). A higher number of MAs was associated with inferior survival. Patients with alterations in epigenetic & TK pathways also had inferior outcomes. MAs were frequently independent of histology & the spectrum of mutations was similar to adult cancers. Exceptional responses were observed with MA-based assignment of therapies (epigenetic, NTRK, RAS/RAF/MEK & ALK). Conclusions: Relapsed/refractory pediatric & AYA cancers have frequent MAs independent of histology. The spectrum of MAs is distinct from de novo disease & potentially reflects tumor evolution & resistance mechanisms. These findings support MA-guided approaches to new drug development paired with adult trials.

Acute myeloid leukemia (AML) continues to represent an area of critical unmet need with respect to new and effective targeted therapies. The Bcl-2 family of pro- and antiapoptotic proteins stands at the crossroads of cellular survival and death, and the expression of and interactions between these proteins determine tumor cell fate. Malignant cells, which are often primed for apoptosis, are particularly vulnerable to the simultaneous disruption of cooperative survival signaling pathways. Indeed, the single agent activity of agents such as mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase kinase (MEK) inhibitors in AML has been modest. Much work in recent years has focused on strategies to enhance the therapeutic potential of the bona fide BH3-mimetic, ABT-737, which inhibits B-cell lymphoma 2 (Bcl-2) and Bcl-xL. Most of these strategies target Mcl-1, an antiapoptotic protein not inhibited by ABT-737. The phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways are central to the growth, proliferation, and survival of AML cells, and there is much interest currently in pharmacologically interrupting these pathways. Dual inhibitors of PI3K and mTOR overcome some intrinsic disadvantages of rapamycin and its derivatives, which selectively inhibit mTOR. In this review, we discuss why combining dual PI3K/mTOR blockade with inhibition of Bcl-2 and Bcl-xL, by virtue of allowing coordinate inhibition of three mutually synergistic pathways in AML cells, may be a particularly attractive therapeutic strategy in AML, the success of which may be predicted for by basal Akt activation.

L’adenocarcinoma pancreatico e’ una delle neoplasie con piu’ alta mortalita’ nei paesi occidentali, con una sopravvivenza media di 6 mesi e una percentuale estremamente bassa di sopravvivenza a lungo termine. L’evento principale nello sviluppo dell’adenocarcinoma pancreatico e’ la mutazione del gene KRAS, che tuttavia e’ particolarmente difficile da colpire a livello molecolare. Strategie terapeutiche piu’ efficaci per l’adenocarcinoma pancreatico possono derivare dall’impiego di terapie molecolari. L'obiettivo di questo lavoro e’ quello di identificare nuovi meccanismi e molecolari e strategie terapeutiche per l’adenocarcinoma pancreatico attraverso l’uso modelli cellulari e murini KRAS mutati. Metodi Abbiamo analizzato i risultatiti dello screening di 50 molecole su piu’ di 500 linee cellulari tumorali (incluso 46 di adenocarcinoma pancreatico). Abbiamo disegnato due strategie differenti incluso: 1) un inibitore di JAK2 che inibisce funzionalmente STAT3 e 2) un inibitore di MEK1/2 (AZD-6244), in monoterapia o in combinazione con un inibitore di PI3K (BKM-120 e GDC-0941), in un modello murino KRAS mutato che ricapitola la progressione istopatologica dell’adenocarcinoma pancreatico. Risultati 1) JAK2: lo screening su larga scala di linee cellulari con un inibitore di JAK2 ha mostrato che l’adenocarcinoma pancreatico mostra una sensitivita’ aumentata ( fino a >30 volte) per questa molecola. La sensitivita’ correla con il livello di espressione di pSTAT3 e gp130, un recettore a monte della cascata di STAT3. Abbiamo inoltre osservato che il sottogruppo di adenocarcinoma pancreatico con alti livelli di STAT3 mostra una attivazione costante del pathway IL6/LIF-gp130. Per definire la funzione di STAT3 nell’adenocarcinoma pancreatico, abbiamo quindi sviluppato un modello murino condizionale per STAT3. STAT3 e’ necessario precocemente per lo sviluppo the di lesioni pre-neoplastiche come PanIN (Neoplasia pancretica intraepiteliale) e ADM (Metaplasia acino-duttale). In aggiunta, l’inattivazione di STAT3 blocca lo sviluppo dell’adenocarcinoma pancreatico in un modello ortotopico. I nostri risultati dimostrano che STAT3 ha un ruolo critico nella inizio e progressione dell’adenocarcinoma pancreatico, indicando che la sua inibizione possa essere una strategia terapeutica efficace. Inoltre dimostra che l’espressione di gp130 e pSTAT3 possa essere un biomarker efficace per predire la risposta a un inbitore di JAK2. 2) MEK/PI3K: un altro dato emerso dal nostro screening cellulare e’ che l’adenocarcionoma pancreatico e’ relativamente resistente a monoterapie. Il profilo dell’inibitore di MEK1/2. AZD-6244, ha mostrato una alta efficacia per l’adenocarcinoma pancreatico. Abbiamo tuttavia notato che per indurre apoptosi era necessario associare un inibitore di PI3K (BKM-120 o GDC-0941). Abbiamo testato questa combinazione in modelli murini di adenocarcinoma pacreatico e comparato con trattamento in monoterapia, agenti tradizionali e placebo. La combinazione di MEK e PI3K ha mostrato di ritardare l’insorgenza dei tumori e di aumentare la soopravvivenza in tumori avanzati, sebbene i tumori tendessero a ricorrere nel lungo termine. Conclusioni Questo lavoro dimostra che 1)JAK2 e’ un target molecolare per il trattamento dell’adenocarcinoma pancreatico, in particolare in tumori con alti livelli di GP130; 2) MEK e PI3K sono essenziali nella progressione dell’adenocarcinoma pancreatico e la loro inibizione combinata potrebbe rappresentare una efficace strategia terapeutica.
Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers in western countries, with a median survival of 6 months and an extremely low percentage of long-term surviving patients. KRAS mutations are known to be a driver event of PDAC, but targeting mutant KRAS has proved challenging. As new targeted agents are becoming available for clinical trial we aimed to design improved therapeutic approaches for the treatment of pancreatic ductal adenocarcinoma by means of in vitro and in vivo models of pancreatic adenocarcinoma. Methods We analyzed the results of a high-throughput screening of >500 human cancer cell lines (including 46 PDAC lines), for sensitivity to 50 clinically-relevant compounds. We designed two different strategies including 1) a JAK2 inhibitor that blocks STAT3 function and 2) a MEK1/2 inhibitor, AZD-6244, for efficacy alone or in combination with the PI3K inhibitors, BKM-120 or GDC-0941, in a KRASG12D-driven GEMM that recapitulates the multi-step pathogenesis of human PDAC. Results 1) JAK2 inhibitor: Large-scale screening of cancer cell lines with a JAK2 inhibitor that blocks STAT3 function revealed a >30-fold range in sensitivity in PDAC, and showed a close correlation of sensitivity with levels of tyrosine-phosphorylated STAT3 and of the gp130 receptor, an upstream signaling component. Correspondingly, upregulation of the IL6/LIF-gp130 pathway accounted for the strong STAT3 activation in PDAC subsets. To define functions of STAT3 in vivo, we developed mouse models that test the impact of conditional inactivation of STAT3 in KRAS-driven PDAC. We showed that STAT3 is required for the development of the earliest pre-malignant pancreatic lesions, acinar-to-ductal metaplasia (ADM) and pancreatic intraepithelial neoplasia (PanIN). Moreover, acute STAT3 inactivation blocked PDAC initiation in a second in vivo model. Our results demonstrate that STAT3 has critical roles throughout the course of PDAC pathogenesis, supporting the development of therapeutic approaches targeting this pathway. Moreover, our work suggests that gp130 and phospho-STAT3 expression may be effective biomarkers for predicting response to JAK2 inhibitors. 2) MEK1/2/PI3K inhibitors: In vitro screens revealed that PDAC cell lines are relatively resistant to single-agent therapies. The response profile to the MEK1/2 inhibitor, AZD-6244, was an outlier, showing the highest selective efficacy in PDAC. While MEK inhibition alone was mainly cytostatic, apoptosis was induced when combined with PI3K inhibitors (BKM-120 or GDC-0941). When tested in a PDAC GEMM and compared to the single agents or vehicle controls, the combination delayed tumor formation in the setting of prevention and extended survival when used to treat advanced tumors, although no durable responses were observed. Conclusions: Our studies point to 1)JAK2 as a therapeutic target in GP130 high pancreatic cancers and 2) important contributions of MEK and PI3K signaling to PDAC pathogenesis suggesting that dual targeting of these pathways may provide benefit in some PDAC patients.

Protein kinases are enzymes that transfer a phosphate group to the threonine, serine, or tyrosine residues of the target protein, regulating its activity. The activity of these enzymes are very important and strictly regulated in the cell as they promote cell proliferation, survival, and migration. In the case of any dysregulation of these enzymes, they can be associated with cancer initiation and progression. Small-molecule kinase inhibitors approved by the FDA for their improved clinical benefits are currently used in targeted therapy for the treatment of various cancers. So far, there are 62 FDA-approved therapeutic agents targeting different protein kinases, eight of which were approved in 2020. Today, kinase inhibitors are used as FDA approved cancer agents and newly developed ones are evaluated in clinical trials. Those protein kinase inhibitors can be grouped as growth factor receptor inhibitors, Ras/Raf/Mek inhibitors, phosphoinositide 3-kinase (PI3K) and cyclin dependent kinase inhibitors, other targets, and agents such as protein kinase c and 3 phosphoinositide-dependent kinase 1. In this chapter, these kinases, their pathways, and their inhibitors will be discussed in detail.

The standard treatment for patients with differentiated thyroid cancer (DTC) is a combination of surgery, radioactive iodine (RAI), and long-term thyroid hormone–suppression therapy. Treatment of patients whose diseases persist, recur, or metastasize remains a challenge. The role of cytotoxic chemotherapy in the treatment of thyroid cancer is limited. The key signaling pathways involved in the pathogenesis of thyroid cancers are the RAS/RAF/MEK & PI3K/Akt/mTOR pathways. Systemic therapy in thyroid cancer involves the use of tyrosine kinase inhibitors targeting the above mentioned pathways which are often both effective in controlling disease and have manageable toxicity. Sorafenib and lenvatinib are approved for advanced radioiodine refractory and poorly differentiated thyroid cancers and vandetanib and cabozantinib for recurrent or metastatic medullary thyroid cancers. Cabozantinib is also approved for the treatment of locally advanced or metastatic radioactive iodine–refractory differentiated thyroid cancer that has progressed after prior VEGF-targeted therapy. The combination of dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) is approved for BRAF V600E mutated unresectable locally advanced anaplastic thyroid cancer. Selpercatinib, RET kinase inhibitor is used for advanced and metastatic RET mutated medullary thyroid cancers and advanced and metastatic RET fusion-positive thyroid cancers of any histologic type. Various clinical trials using newer molecules targeting the aforementioned pathways are ongoing.