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1.
RAF kinase dimerization: implications for drug discovery and clinical outcomes.
Brummer, T, McInnes, C
Oncogene. 2020;(21):4155-4169
Abstract
The RAF kinases activated by RAS GTPases regulate cell growth and division by signal transduction through the ERK cascade and mutations leading to constitutive activity are key drivers of human tumors, as are upstream activators including RAS and receptor tyrosine kinases. The development of first-generation RAF inhibitors, including vemurafenib (VEM) and dabrafenib led to initial excitement due to high response rates and profound regression of malignant melanomas carrying BRAFV600E mutations. The excitement about these unprecedented response rates, however, was tempered by tumor unresponsiveness through both intrinsic and acquired drug-resistance mechanisms. In recent years much insight into the complexity of the RAS-RAF axis has been obtained and inactivation and signal transduction mechanisms indicate that RAF dimerization is a critical step in multiple cellular contexts and plays a key role in resistance. Both homo- and hetero-dimerization of BRAF and CRAF can modulate therapeutic response and disease progression in patients treated with ATP-competitive inhibitors and are therefore highly clinically significant. Ten years after the definition of the RAF dimer interface (DIF) by crystallography, this review focuses on the implications of RAF kinase dimerization in signal transduction and for drug development, both from a classical ATP-competitive standpoint and from the perspective of new therapeutic strategies including inhibiting dimer formation. A structural perspective of the DIF, how dimerization impacts inhibitor activation and the structure-based design of next-generation RAF kinase inhibitors with unique mechanisms of action is presented. We also discuss potential fields of application for DIF inhibitors, ranging from non-V600E oncoproteins and BRAF fusions to tumors driven by aberrant receptor tyrosine kinase or RAS signaling.
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2.
Molecular therapies for HCC: Looking outside the box.
Faivre, S, Rimassa, L, Finn, RS
Journal of hepatology. 2020;(2):342-352
Abstract
Over the past decade, sorafenib has been the only systemic agent with proven clinical efficacy for patients with unresectable hepatocellular carcinoma (HCC). Recently, lenvatinib was shown to be non-inferior to sorafenib, while regorafenib, cabozantinib, and ramucirumab were shown to be superior to placebo in patients failing sorafenib. In addition, trials of immune checkpoint inhibitors reported encouraging efficacy signals. However, apart from alpha-fetoprotein, which is used to select patients for ramucirumab, no biomarkers are available to identify patients that may respond to a specific treatment. Different synergisms have been postulated based on the potential interplay between antiangiogenic drugs and immunotherapy, with several clinical trials currently testing this hypothesis. Indeed, encouraging preliminary results of phase I studies of bevacizumab plus atezolizumab and lenvatinib plus pembrolizumab have led to the design of ongoing phase III trials, including both antiangiogenics and immune checkpoint inhibitors in the front-line setting. Other important phase II studies have tested molecular therapies directed against different novel targets, such as transforming growth factor-beta, MET (hepatocyte growth factor receptor), and fibroblast growth factor receptor 4. These studies integrated translational research with the aim of better defining the biological tumour profile and identifying tumour and blood biomarkers that select patients who may really benefit from a specific molecular therapy. Importantly, good safety profiles make these drugs suitable for future combinations. In this review, we discuss the most recent data on novel combination strategies and targets, as well as looking ahead to the future role of molecular therapies in the treatment of patients with advanced HCC.
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3.
Novel therapeutic options for radioiodine-refractory thyroid cancer: redifferentiation and beyond.
Bulotta, S, Celano, M, Costante, G, Russo, D
Current opinion in oncology. 2020;(1):13-19
Abstract
PURPOSE OF REVIEW Radioiodine-refractory thyroid cancers represent the main cause of thyroid cancer-related death. At present, targeted therapies with multikinase inhibitors represent a unique therapeutic tool, though they have limited benefit on patient survival and severe drug-associated adverse events. This review summarizes current treatment strategies for radioiodine-refractory thyroid cancer and focuses on novel approaches to redifferentiate thyroid cancer cells to restore responsiveness to radioiodine administration. RECENT FINDINGS We summarize and discuss recent clinical trial findings and early data from real-life experiences with multikinase-inhibiting drugs. Possible alternative strategies to traditional redifferentiation are also discussed. SUMMARY The current review focuses primarily on the major advancements in the knowledge of the pathophysiology of iodine transport and metabolism and the genetic and epigenetic alterations occurring in thyroid neoplasia as described using preclinical models. Results of clinical studies employing new compounds to induce thyroid cancer cell redifferentiation by acting against specific molecular targets are also discussed. Finally, we describe the current scenario emerging from such findings as well as future perspectives.
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4.
Tyrosine Kinase Inhibitors and Hepatocellular Carcinoma.
da Fonseca, LG, Reig, M, Bruix, J
Clinics in liver disease. 2020;(4):719-737
Abstract
Sorafenib was the first tyrosine kinase inhibitor (TKI) that showed success in extending survival in patients with advanced hepatocellular carcinoma (HCC). In recent years, additional TKIs have been shown to improve survival and expanded the armamentarium for treating this malignancy. The current landscape includes other classes of drugs, such as immune checkpoint inhibitors and monoclonal antibodies. The challenge is now placed on how to best select, combine, and sequence drugs with the goal of improving efficacy and minimizing toxicities to deliver better outcomes for HCC patients.
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5.
Expert Perspectives On Clinical Challenges: Expert Perspectives: Challenges in Scleroderma.
Simms, RW
Arthritis & rheumatology (Hoboken, N.J.). 2020;(9):1415-1426
Abstract
You are consulted to evaluate a 56-year-old woman with known Raynaud's phenomenon, finger swelling of several; months' duration, and new hypertension with a blood pressure of 160/100 mm/Hg. She also reports progressive shortness of breath. Physical examination reveals telangiectasias, sclerodactyly, and proximal skin sclerosis (thick shiny skin on the chest and upper arms), and bibasilar crackles are found on chest examination. Laboratory tests reveal evidence of microangiopathic hemolytic anemia, thrombocytopenia, and elevation of the serum creatinine level (previously normal), and chest computed tomography shows evidence of ground-glass opacification in both lower lung fields.
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6.
Myositis - A common but underreported adverse effect of osimertinib: Case series and review of the literature.
Parafianowicz, P, Krishan, R, Beutler, BD, Islam, RX, Singh, T
Cancer treatment and research communications. 2020;:100254
Abstract
BACKGROUND Lung cancer is the second most common cancer in both men and women and the leading cause of cancer death worldwide. The development of novel tyrosine kinase inhibitors (TKIs) represented a paradigm shift in the management of lung cancer and has resulted in markedly prolonged survival. Osimertinib is a TKI that was fast-tracked by the United States Food and Drug Administration in 2015 and subsequently approved for the treatment of metastatic epidermal growth factor receptor T790M mutation-positive non-small cell lung cancer. However, despite the generally favorable outcomes associated with osimertinib, rapid development and deployment of any new drug increases the risk of unforeseen adverse effects. Post-marketing surveillance studies therefore play an important role in further elucidating the risks and benefits of novel anti-neoplastic agents. MATERIAL AND METHODS We describe four patients with non-small cell lung cancer who developed myositis after beginning treatment with osimertinib. In addition, we review the literature on osimertinib-associated myositis. Using PubMed, the following terms were searched and relevant citations assessed: creatine phosphokinase, myositis, osimertinib, rhabdomyolysis, osimertinib, and Tagrisso. CASE PRESENTATION Thirty-eight patients were treated with osimertinib in our community clinic. Four with non-small cell lung cancer developed myositis after beginning treatment. The onset of symptoms and/or elevation of creatine phosphokinase occurred between two weeks and eleven months after osimertinib was initiated. Alternative causes for myositis were not identified. In two patients, myositis resolved within one month of withdrawing treatment. Two other patients continued osimertinib treatment with close monitoring. CONCLUSION Myositis is a serious and potentially underreported adverse effect of osimertinib. Previous studies suggest that osimertinib-associated myositis is rare, occurring in less than 1% of patients. However, myositis occurred in over 10% of patients treated with osimertinib in our clinic population. We suggest regular monitoring for myositis among patients being treated with osimertinib and dose-reduction or cessation of treatment if clinically indicated.
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7.
FLT3 inhibitors in the treatment of acute myeloid leukemia: current status and future perspectives.
Mosquera Orgueira, A, Bao Pérez, L, Mosquera Torre, A, Peleteiro Raíndo, A, Cid López, M, Díaz Arias, JÁ, Ferreiro Ferro, R, Antelo Rodríguez, B, González Pérez, MS, Albors Ferreiro, M, et al
Minerva medica. 2020;(5):427-442
Abstract
Mutations in the FMS-like tyrosine kinase 3 (FLT3) gene arise in 25-30% of all acute myeloid leukemia (AML) patients. These mutations lead to constitutive activation of the protein product and are divided in two broad types: internal tandem duplication (ITD) of the juxtamembrane domain (25% of cases) and point mutations in the tyrosine kinase domain (TKD). Patients with FLT3 ITD mutations have a high relapse risk and inferior cure rates, whereas the role of FLT3 TKD mutations still remains to be clarified. Additionally, growing research indicates that FLT3 status evolves through a disease continuum (clonal evolution), where AML cases can acquire FLT3 mutations at relapse - not present in the moment of diagnosis. Several FLT3 inhibitors have been tested in patients with FLT3-mutated AML. These drugs exhibit different kinase inhibitory profiles, pharmacokinetics and adverse events. First-generation multi-kinase inhibitors (sorafenib, midostaurin, lestaurtinib) are characterized by a broad-spectrum of drug targets, whereas second-generation inhibitors (quizartinib, crenolanib, gilteritinib) show more potent and specific FLT3 inhibition, and are thereby accompanied by less toxic effects. Notwithstanding, all FLT3 inhibitors face primary and acquired mechanisms of resistance, and therefore the combinations with other drugs (standard chemotherapy, hypomethylating agents, checkpoint inhibitors) and its application in different clinical settings (upfront therapy, maintenance, relapsed or refractory disease) are under study in a myriad of clinical trials. This review focuses on the role of FLT3 mutations in AML, pharmacological features of FLT3 inhibitors, known mechanisms of drug resistance and accumulated evidence for the use of FLT3 inhibitors in different clinical settings.
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8.
Therapy after cyclin-dependent kinase inhibition in metastatic hormone receptor-positive breast cancer: Resistance mechanisms and novel treatment strategies.
Sharifi, MN, Anandan, A, Grogan, P, O'Regan, RM
Cancer. 2020;(15):3400-3416
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Abstract
Endocrine therapy has been the standard of care for patients with metastatic hormone receptor (HR)-positive, HER2-negative breast cancer since the 1970s, improving survival while avoiding the toxicities associated with cytotoxic chemotherapy. However, all HR-positive tumors ultimately develop resistance to endocrine therapy. Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors have more recently become an important component of the management of this breast cancer subtype, significantly delaying time to the disease progression and improving survival when combined with endocrine therapy. However, as with endocrine therapy alone, treatment resistance remains a universal phenomenon. As more women receive CDK4/6 inhibitors as part of their treatment, the management of de novo and acquired resistance to combined CDK4/CDK6 inhibitor plus endocrine therapy regimens has emerged as an important clinical challenge. Several resistance mechanisms have been described, including alterations in the CDK4/6/cyclin D complex or its major effector retinoblastoma protein (pRb), bypass signaling through other cyclin/CDK complexes and activation of upstream signaling pathways, in particular the PI3K/mTOR pathway, but robust biomarkers to predict resistance remain elusive, and the role for continuing CDK4/6 inhibitors after progression remains under investigation. Novel strategies being evaluated in clinical trials include the continuation of CDK4/6 inhibitors through progression, as well as triplet therapy combinations with PI3K inhibitors or immune checkpoint inhibitors.
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9.
ChoK-ing the Pathogenic Bacteria: Potential of Human Choline Kinase Inhibitors as Antimicrobial Agents.
Khalifa, M, Few, LL, See Too, WC
BioMed research international. 2020;:1823485
Abstract
Novel antimicrobial agents are crucial to combat antibiotic resistance in pathogenic bacteria. Choline kinase (ChoK) in bacteria catalyzes the synthesis of phosphorylcholine, which is subsequently incorporated into the cell wall or outer membrane. In certain species of bacteria, phosphorylcholine is also used to synthesize membrane phosphatidylcholine. Numerous human ChoK inhibitors (ChoKIs) have been synthesized and tested for anticancer properties. Inhibition of S. pneumoniae ChoK by human ChoKIs showed a promising effect by distorting the cell wall and retarded the growth of this pathogen. Comparison of amino acid sequences at the catalytic sites of putative choline kinases from pathogenic bacteria and human enzymes revealed striking sequence conservation that supports the potential application of currently available ChoKIs for inhibiting bacterial enzymes. We also propose the combined use of ChoKIs and nanoparticles for targeted delivery to the pathogen while shielding the human host from any possible side effects of the inhibitors. More research should focus on the verification of putative bacterial ChoK activities and the characterization of ChoKIs with active enzymes. In conclusion, the presence of ChoK in a wide range of pathogenic bacteria and the distinct function of this enzyme has made it an attractive drug target. This review highlighted the possibility of "choking" bacterial ChoKs by using human ChoKIs.
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10.
Skeletal Muscle Loss during Multikinase Inhibitors Therapy: Molecular Pathways, Clinical Implications, and Nutritional Challenges.
Rinninella, E, Cintoni, M, Raoul, P, Pozzo, C, Strippoli, A, Ponziani, FR, Pompili, M, Bria, E, Tortora, G, Gasbarrini, A, et al
Nutrients. 2020;(10)
Abstract
In cancer patients, loss of muscle mass is significantly associated with low tolerability of chemotherapy and poor survival. Despite the great strides in the treatment of cancer, targeted therapies such as tyrosine kinase inhibitors (TKIs) could exacerbate muscle wasting. Over recent years, the impact of skeletal muscle loss during TKI therapy on clinical outcomes has been in the spotlight. In this review, we focus on the different molecular pathways of TKIs potentially involved in muscle wasting. Then, we report the results of the studies assessing the effects of different TKI therapies-such as sorafenib, regorafenib, sunitinib, and lenvatinib-on muscle mass, and highlight their potential clinical implications. Finally, we discuss an integrative nutritional approach to be adopted during TKI treatment. The assessment of muscle mass from computerized tomography imaging could be helpful in predicting toxicity and prognosis in patients treated with TKI such as sorafenib. Early recognition of low muscle mass and effective personalized nutritional support could prevent or attenuate muscle mass wasting. However, the role of nutrition is still overlooked, and future clinical trials are needed to find the optimal nutritional support to countermeasure muscle mass depletion during TKI therapy.