NCOA4-RET fusion in colorectal cancer: Therapeutic challenge using patient-derived tumor cell lines

Selpercatinib combination with the mitochondria-targeted antioxidant MitoQ effectively suppresses RET-mutant thyroid cancer

Genetic alternation of REarranged during Transfection (RET) that leads to constitutive RET activation is a crucial etiological factor for thyroid cancer. RET is known to regulate mitochondrial processes, although the underlying molecular mechanisms remain unclear. We previously showed that the multi-kinase inhibitors vandetanib and cabozantinib increase the mitochondrial membrane potential (Δψm) in RET-mutated thyroid tumor cells and that this effect can be exploited to increase mitochondrial enrichment of Δψm-sensitive agents in the tumor cells. In this study, we hypothesized that the RET-selective inhibitor, selpercatinib, can increase Δψm and, subsequently, tumor cell uptake of the mitochondria-targeted ubiquinone (MitoQ) to the level to break the mitochondrial homeostasis and induce lethal responses in RET-mutated thyroid tumor cells. We show that selpercatinib significantly increased Δψm, and its combination with MitoQ synergistically suppressed RET-mutated human thyroid tumor cells, which we validated using RET-targeted genetic approaches. Selpercatinib and MitoQ, in combination, also suppressed CCDC6-RET fusion cell line xenografts in mice and prolonged animal survival more effectively than single treatments of each agent. Moreover, we treated two patients with CCDC6-RET or RETM918T thyroid cancer, who could not take selpercatinib at regular doses due to adverse effects, with a dose-reduced selpercatinib and MitoQ combination. In response to this combination therapy, both patients showed tumor reduction. The quality of life of one patient significantly improved over a year until the tumor relapsed. This combination of selpercatinib with MitoQ may have therapeutic potential for patients with RET-mutated tumors and intolerant to regular selpercatinib doses.

Kinase Fusions in Spitz Melanocytic Tumors: The Past, the Present, and the Future

In recent years, particular interest has developed in molecular biology applied to the field of dermatopathology, with a focus on nevi of the Spitz spectrum. From 2014 onwards, an increasing number of papers have been published to classify, stratify, and correctly frame molecular alterations, including kinase fusions. In this paper, we try to synthesize the knowledge gained in this area so far. In December 2023, we searched Medline and Scopus for case reports and case series, narrative and systematic reviews, meta-analyses, observational studies-either longitudinal or historical, case series, and case reports published in English in the last 15 years using the keywords spitzoid neoplasms, kinase fusions, ALK, ROS1, NTRK (1-2-3), MET, RET, MAP3K8, and RAF1. ALK-rearranged Spitz tumors and ROS-1-rearranged tumors are among the most studied and characterized entities in the literature, in an attempt (although not always successful) to correlate histopathological features with the probable molecular driver alteration. NTRK-, RET-, and MET-rearranged Spitz tumors present another studied and characterized entity, with several rearrangements described but as of yet incomplete information about their prognostic significance. Furthermore, although rarer, rearrangements of serine-threonine kinases such as BRAF, RAF1, and MAP3K8 have also been described, but more cases with more detailed information about possible histopathological alterations, mechanisms of etiopathogenesis, and also prognosis are needed. The knowledge of molecular drivers is of great interest in the field of melanocytic diagnostics, and it is important to consider that in addition to immunohistochemistry, molecular techniques such as FISH, PCR, and/or NGS are essential to confirm and classify the different patterns of mutation. Future studies with large case series and molecular sequencing techniques are needed to allow for a more complete and comprehensive understanding of the role of fusion kinases in the spitzoid tumor family.

Integrated budget impact model to estimate the impact of introducing selpercatinib as a tumor-agnostic treatment option for patients with RET-altered solid tumors in the US

OBJECTIVE

To estimate the potential budget impact on US third party payers (commercial or Medicare) associated with addition of selpercatinib as a tumor-agnostic treatment for patients with Rearranged during Transfection (RET)-altered solid tumors.

METHODS

An integrated budget impact model (iBIM) with 3-year (Y) time horizon was developed for 19 RET-altered tumors. It is referred to as an integrated model because it is a single model that integrated results across multiple tumor types (as opposed to tumor-specific models developed traditionally). The model estimated eligible patient populations and included tumor-specific comparator treatments for each tumor type. Estimated annual total costs (2022USD, $) included costs of drug, administration, supportive care, and toxicity. For a one-million-member plan, the number of patients with RET-altered tumors eligible for treatment, incremental total costs, and incremental per-member per-month (PMPM) costs associated with introduction of selpercatinib treatment were estimated. Uncertainty associated with model parameters was assessed using various sensitivity analyses.

RESULTS

Commercial perspective estimated 11.68 patients/million with RET-altered tumors as treatment-eligible annually, of which 7.59 (Y1), 8.17 (Y2), and 8.76 (Y3) patients would be selpercatinib-treated (based on forecasted market share). The associated incremental total and PMPM costs (commercial) were estimated to be: $873,099 and $0.073 (Y1), $2,160,525 and $0.180 (Y2), and $2,561,281 and $0.213 (Y3), respectively. The Medicare perspective estimated 55.82 patients/million with RET-altered tumors as treatment-eligible annually, of which 36.29 (Y1), 39.08 (Y2), and 41.87 (Y3) patients would be selpercatinib-treated. The associated incremental total and PMPM costs (Medicare) were estimated to be: $4,447,832 and $0.371 (Y1), $11,076,422 and $0.923 (Y2), and $12,637,458 and $1.053 (Y3), respectively. One-way sensitivity analyses across both perspectives identified drug costs, selpercatinib market share, incidence of RET, and treatment duration as significant drivers of incremental costs.

CONCLUSIONS

Three-year incremental PMPM cost estimates suggest a modest impact on payer-budgets associated with introduction of tumor-agnostic selpercatinib treatment.

Novel biomarkers used for early diagnosis and tyrosine kinase inhibitors as targeted therapies in colorectal cancer

Colorectal cancer (CRC) is the third most common and second most lethal type of cancer worldwide, presenting major health risks as well as economic costs to both people and society. CRC survival chances are significantly higher if the cancer is diagnosed and treated early. With the development of molecular biology, numerous initiatives have been undertaken to identify novel biomarkers for the early diagnosis of CRC. Pathological disorders can be diagnosed at a lower cost with the help of biomarkers, which can be detected in stool, blood, and tissue samples. Several lines of evidence suggest that the gut microbiota could be used as a biomarker for CRC screening and treatment. CRC treatment choices include surgical resection, chemotherapy, immunotherapy, gene therapy, and combination therapies. Targeted therapies are a relatively new and promising modality of treatment that has been shown to increase patients' overall survival (OS) rates and can inhibit cancer cell development. Several small-molecule tyrosine kinase inhibitors (TKIs) are being investigated as potential treatments due to our increasing awareness of CRC's molecular causes and oncogenic signaling. These compounds may inhibit critical enzymes in controlling signaling pathways, which are crucial for CRC cells' development, differentiation, proliferation, and survival. On the other hand, only one of the approximately 42 TKIs that demonstrated anti-tumor effects in pre-clinical studies has been licensed for clinical usage in CRC. A significant knowledge gap exists when bringing these tailored medicines into the clinic. As a result, the emphasis of this review is placed on recently discovered biomarkers for early diagnosis as well as tyrosine kinase inhibitors as possible therapy options for CRC.

Precious Gene: The Application of RET-Altered Inhibitors

The well-known proto-oncogene rearrangement during transfection (RET), also known as ret proto-oncogene Homo sapiens (human), is a rare gene that is involved in the physiological development of some organ systems and can activate various cancers, such as non-small cell lung cancer, thyroid cancer, and papillary thyroid cancer. In the past few years, cancers with RET alterations have been treated with multikinase inhibitors (MKIs). However, because of off-target effects, these MKIs have developed drug resistance and some unacceptable adverse effects. Therefore, these MKIs are limited in their clinical application. Thus, the novel highly potent and RET-specific inhibitors selpercatinib and pralsetinib have been accelerated for approval by the Food and Drug Administration (FDA), and clinical trials of TPX-0046 and zetletinib are underway. It is well tolerated and a potential therapeutic for RET-altered cancers. Thus, we will focus on current state-of-the-art therapeutics with these novel RET inhibitors and show their efficacy and safety in therapy.

Biomarkers in Metastatic Colorectal Cancer: Status Quo and Future Perspective

Colorectal cancer (CRC) is the third most frequent cancer worldwide, and its incidence is steadily increasing. During the last two decades, a tremendous improvement in outcome has been achieved, mainly due to the introduction of novel drugs, targeted treatment, immune checkpoint inhibitors (CPIs) and biomarker-driven patient selection. Moreover, progress in molecular diagnostics but also improvement in surgical techniques and local ablative treatments significantly contributed to this success. However, novel therapeutic approaches are needed to further improve outcome in patients diagnosed with metastatic CRC. Besides the established biomarkers for mCRC, such as microsatellite instability (MSI) or mismatch repair deficiency (dMMR), RAS/BRAF, sidedness and HER2 amplification, new biomarkers have to be identified to better select patients who derive the most benefit from a specific treatment. In this review, we provide an overview about therapeutic relevant and established biomarkers but also shed light on potential promising markers that may help us to better tailor therapy to the individual mCRC patient in the near future.

Utilisation of semiconductor sequencing for detection of actionable fusions in solid tumours

Oncogenic fusions represent compelling druggable targets in solid tumours highlighted by the recent site agnostic FDA approval of larotrectinib for NTRK rearrangements. However screening for fusions in routinely processed tissue samples is constrained due to degradation of nucleic acid as a result of formalin fixation., To investigate the clinical utility of semiconductor sequencing optimised for detection of actionable fusion transcripts in formalin fixed samples, we have undertaken an analysis of test trending data generated by a clinically validated next generation sequencing platform designed to capture 867 of the most clinically relevant druggable driver-partner oncogenic fusions. Here we show across a real-life cohort of 1112 patients with solid tumours that actionable fusions occur at high frequency (7.4%) with linkage to a wide range of targeted therapy protocols including seven fusion-drug matches with FDA/EMA approval and/or NCCN/ESMO recommendations and 80 clinical trials. The more prevalent actionable fusions identified were independent of tumour type in keeping with signalling via evolutionary conserved RAS/RAF/MEK/ERK, PI3K/AKT/MTOR, PLCy/PKC and JAK/STAT pathways. Taken together our data indicates that semiconductor sequencing for detection of actionable fusions can be integrated into routine diagnostic pathology workflows enabling the identification of personalised treatment options that have potential to improve clinical cancer management across many tumour types.

RET signaling pathway and RET inhibitors in human cancer

Rearranged during transfection (RET) receptor tyrosine kinase was first identified over thirty years ago as a novel transforming gene. Since its discovery and subsequent pathway characterization, RET alterations have been identified in numerous cancer types and are most prevalent in thyroid carcinomas and non-small cell lung cancer (NSCLC). In other tumor types such as breast cancer and salivary gland carcinomas, RET alterations can be found at lower frequencies. Aberrant RET activity is associated with poor prognosis of thyroid and lung carcinoma patients, and is strongly correlated with increased risk of distant metastases. RET aberrations encompass a variety of genomic or proteomic alterations, most of which confer constitutive activation of RET. Activating RET alterations, such as point mutations or gene fusions, enhance activity of signaling pathways downstream of RET, namely PI3K/AKT, RAS/RAF, MAPK, and PLCγ pathways, to promote cell proliferation, growth, and survival. Given the important role that mutant RET plays in metastatic cancers, significant efforts have been made in developing inhibitors against RET kinase activity. These efforts have led to FDA approval of Selpercatinib and Pralsetinib for NSCLC, as well as, additional selective RET inhibitors in preclinical and clinical testing. This review covers the current biological understanding of RET signaling, the impact of RET hyperactivity on tumor progression in multiple tumor types, and RET inhibitors with promising preclinical and clinical efficacy.

NCOA4: An Immunomodulation-Related Prognostic Biomarker in Colon Adenocarcinoma and Pan-Cancer

Treatment of cancer in humans requires a thorough understanding of the multiple pathways by which it develops. Recent studies suggest that nuclear receptor coactivator 4 (NCOA4) may be a predictive biomarker for renal cancer. In the present work, TCGA, GEPIA, and several bioinformatics approaches were used to analyze the NCOA4 expression patterns, prognostic relevance, and association between NCOA4 and clinicopathological features and immune cell infiltration. We investigated NCOA4 expression in malignancies. Low NCOA4 expression was associated with poor overall survival in individuals with malignancies such as cholangiocarcinoma, colon adenocarcinoma, and clear cell renal carcinoma. We also analyzed NCOA4 DNA methylation in normal and primary tumor tissues and investigated possible functional pathways underlying NCOA4-mediated oncogenesis. In conclusion, downregulation of NCOA4 is associated with poor prognosis, and NCOA4 may be a predictive biomarker for COAD.

Pan-Cancer Biomarkers: Changing the Landscape of Molecular Testing

CONTEXT.—

The increasing use of large panel next-generation sequencing technologies in clinical settings has facilitated the identification of pan-cancer biomarkers, which can be diagnostic, prognostic, predictive, or most importantly, actionable.

OBJECTIVE.—

To discuss recently approved and emerging pan-cancer and multihistology biomarkers as well as testing methodologies.

DATA SOURCES.—

The US Food and Drug Administration approval documents, National Comprehensive Cancer Network guidelines, literature, and authors' own publications.

CONCLUSIONS.—

Since 2017, the US Food and Drug Administration has approved genotype-directed therapies for pan-cancer biomarkers, including microsatellite instability, neurotrophic receptor kinases fusions, and high-tumor mutation burden. Both the importance and rarity of these biomarkers have increased the prevalence of genomic profiling across solid malignancies. As an integral part of the management team of patients with advanced cancer, pathologists need to be aware of these emerging biomarkers, the therapies for which they determine eligibility, and the strengths and pitfalls of the available clinical assays.

A Brief Overview and Update on Major Molecular Genomic Alterations in Solid, Bone and Soft Tissue Tumors, Hematopoietic As Well As Lymphoid Malignancies

CONTEXT.—

Recent advances in comprehensive genomic profiling by next-generation sequencing have uncovered the genomic alterations at the molecular level for many types of tumors; as such, numerous small specific molecules that target these alterations have been developed and widely used in the management of these cancers.

OBJECTIVE.—

To provide a concise molecular genomic update in solid, bone and soft tissue tumors, hematopoietic as well as lymphoid malignancies; discuss its clinical applications; and familiarize practicing pathologists with the emerging cancer biomarkers and their diagnostic utilities.

DATA SOURCES.—

This review is based on the National Comprehensive Cancer Network guidelines and peer-reviewed English literature.

CONCLUSIONS.—

Tumor-specific biomarkers and molecular/genomic alterations, including pan-cancer markers, have been significantly expanded in the past decade thanks to large-scale high-throughput technologies and will continue to emerge in the future. These biomarkers can be of great value in diagnosis, prognosis, and/or targeted therapy/treatment. Familiarization with these emerging and ever-changing tumor biomarkers will undoubtedly aid pathologists in making accurate and state-of-the-art diagnoses and enable them to be more actively involved in the care of cancer patients.

Low expression of ferritinophagy-related NCOA4 gene in relation to unfavorable outcome and defective immune cells infiltration in clear cell renal carcinoma

Background

Clear cell renal cell carcinoma is susceptible to ferroptosis, and immunotherapy is recently recommended as a priority for the initial treatment of metastatic clear cell renal carcinoma. Increased ferroptosis and immune activation can synergistically reinforce each other in killing cancer cells. NCOA4 depletion can eliminate iron accumulation and thus weaken ferroptosis. Here, we aim to identify and validate the association between NCOA4 expression, clinicopathologic characteristics, and overall survival in ccRCC by using The Cancer Genome Atlas and Gene Expression Omnibus databases. We further analyze the interacted proteins of NCOA4 and infiltrated immune cells via TIMER and GEPIA databases.

Methods

NCOA4 expression in clear cell renal carcinoma (ccRCC) tissues and normal adjacent tissues in The Cancer Genome Atlas (TCGA) data were primarily screened, and further validated in another independent cohort from the gene expression omnibus (GEO) database and human protein atlas. The relationships of NCOA4 expression and clinicopathologic parameters and overall survival (OS) were assessed using multivariate methods and Kaplan-Meier survival curves. And the proteins network with which NCOA4 interacted were also built using the online STRING website. Meanwhile, we use TIMER and GEPIA databases to investigate the relationships between NCOA4 expression and infiltrated immune cells and their corresponding gene marker sets.

Results

Contrast to normal tissue, NCOA4 expression was lower in ccRCC tumor tissue(p < 0.05). Lower NCOA4 expression was closely associated with high-grade malignancy and advanced TNM stage. Univariate and multivariate analysis indicated the overall survival of ccRCC cases with low NCOA4 level is shorter than those of patients with high NCOA4 expression (p < 0.05). FTL and FTH1 were the important proteins interacting with NCOA4. ccRCC with NCOA4 deficiency presented the paucity of infiltrated immune cells and their matching marker sets, including CD8+ T cells.

Conclusion

Deficient NCOA4 expression was related to disease progression and poor prognosis, as well as impaired infiltration of immune cells in ccRCC.

A Series of RET Fusion Spitz Neoplasms With Plaque-Like Silhouette and Dyscohesive Nesting of Epithelioid Melanocytes

ABSTRACT

Two distinct studies have shown that RET fusions are found in 3%-4% of Spitz neoplasms. RET fusions have been well described in papillary thyroid cancer, non-small-cell lung cancer, breast cancer, and soft-tissue mesenchymal tumors as well as some other neoplasms. However, there are no comprehensive descriptions to date of the characteristic morphologic, clinical, or genomic findings in RET fusion Spitz neoplasms. In this study, we identified 5 cases of RET fusion Spitz neoplasms. These tumors showed characteristic morphologic features which included plaque-like silhouette and monotonous epithelioid cytology with expansile and dyscohesive nesting. Four of 5 patients including 1 diagnosed as Spitz melanoma had clinical follow-up all of which was uneventful. Furthermore, we describe the genomic sequences in 4 of these cases, 2 of which have previously described KIF5B-RET fusion and 2 of which had a novel LMNA-RET fusion. We believe this report significantly contributes to our current knowledge regarding Spitz neoplasms and describes characteristics features which can help with recognition of the RET subgroup of Spitz.

NTRK and other recently described kinase fusion positive uterine sarcomas: A review of a group of rare neoplasms

The landscape of uterine sarcomas has greatly expanded in recent years to include neoplasms with recurrent gene fusions, such as BCOR and YWHAE translocated high-grade endometrial stromal sarcomas. Sophisticated molecular techniques have also resulted in the description of "new" entities associated with recurrent kinase fusions involving NTRK and RET as well as COL1A1-PDGFB rearranged uterine sarcomas. These rare neoplasms will be discussed in this review, highlighting that some of the underlying molecular events are clinically actionable and potentially susceptible to targeted therapy. While relatively few of these neoplasms have been described to date, likely being previously lumped under the spectrum of undifferentiated uterine sarcoma, the number of cases will expand in the future given their recognition and the increasing availability of molecular testing. These neoplasms have overlapping morphology (often with a "fibrosarcoma-like" appearance) and immunohistochemical features, and are characterized by variable clinical outcomes. Although immunohistochemistry may assist in some cases, a definitive subclassification requires confirmatory molecular studies. As these molecular assays may not be routinely available in most laboratories, referral to reference centers may be needed. In order to assist the pathologist, we suggest a diagnostic algorithm for routine practice when dealing with a malignant or potentially malignant uterine spindle cell neoplasm.

Transcriptome and Gene Fusion Analysis of Synchronous Lesions Reveals lncMRPS31P5 as a Novel Transcript Involved in Colorectal Cancer

Fusion genes and epigenetic regulators (i.e., miRNAs and long non-coding RNAs) constitute essential pieces of the puzzle of the tumor genomic landscape, in particular in mechanisms behind the adenoma-to-carcinoma progression of colorectal cancer (CRC). In this work, we aimed to identify molecular signatures of the different steps of sporadic CRC development in eleven patients, of which synchronous samples of adenomas, tumors, and normal tissues were analyzed by RNA-Seq. At a functional level, tumors and adenomas were all characterized by increased activity of the cell cycle, cell development, cell growth, and biological proliferation functions. In contrast, organic survival and apoptosis-related functions were inhibited both in tumors and adenomas at different levels. At a molecular level, we found that three individuals shared a tumor-specific fusion named MRPS31-SUGT1, generated through an intra-chromosomal translocation on chromosome 13, whose sequence resulted in being 100% identical to the long non-coding RNA (lncRNA) MRPS31P5. Our analyses suggest that MRPS31P5 could take part to a competitive endogenous (ce)RNA network by acting as a miRNA sponge or/and as an interactor of other mRNAs, and thus it may be an important gene expression regulatory factor and could be used as a potential biomarker for the detection of early CRC events.

Recurrent RET gene fusions in paediatric spindle mesenchymal neoplasms

AIMS

The classification of paediatric spindle mesenchymal tumours is evolving, and the spectrum of so-called 'infantile fibrosarcoma' has expanded to include tumours with NTRK, BRAF and MET gene fusions. RET-rearranged paediatric spindle cell neoplasms are an emerging group; there is sparse literature on their clinical, pathological and genetic features, and their nosological place in the canon of soft tissue tumours is uncertain. In this study, we report five RET-rearranged paediatric spindle cell tumours with fusion partners MYH10, KIAA1217 and CLIP2.

METHODS AND RESULTS

The tumours occurred in the pelvic region, paraspinal region, kidney and subcutaneous tissue of hand and abdomen. The patients' ages ranged from 6 months to 13 years (median 1 year). The tumours were composed of monomorphic spindle cells arranged in a fascicular pattern. Lesional cells had minimally atypical ovoid or tapered nuclei and pale cytoplasm with indistinct borders. Necrosis was not identified. Mitoses numbered three to 12 per 10 high-power field. Cases showed inconsistent and variable expression of S100, CD34 and SMA. Clinical behaviour ranged from small lesions potentially cured by simple resection to large lesions exhibiting metastasis, but responsive to kinase inhibitor therapy.

CONCLUSIONS

Our findings help to define RET-rearranged spindle cell tumours. Although it is likely that these tumours comprise part of the morphological and clinical spectrum of infantile fibrosarcoma (IFS), identification of RET gene alteration is important for its unique therapeutic implications.

Molecular-Biology-Driven Treatment for Metastatic Colorectal Cancer

BACKGROUND

Metastatic CRC (mCRC) is a molecular heterogeneous disease. The aim of this review is to give an overview of molecular-driven treatment of mCRC patients.

METHODS

A review of clinical trials, retrospective studies and case reports was performed regarding molecular biomarkers with therapeutic implications.

RESULTS

RAS wild-type status was confirmed as being crucial for anti-epidermal growth factor receptor (EGFR) monoclonal antibodies and for rechallenge strategy. Antiangiogenic therapies improve survival in first- and second-line settings, irrespective of RAS status, while tyrosine kinase inhibitors (TKIs) remain promising in refractory mCRC. Promising results emerged from anti-HER2 drugs trials in HER2-positive mCRC. Target inhibitors were successful for BRAFV600E mutant mCRC patients, while immunotherapy was successful for microsatellite instability-high/defective mismatch repair (MSI-H/dMMR) or DNA polymerase epsilon catalytic subunit (POLE-1) mutant patients. Data are still lacking on NTRK, RET, MGMT, and TGF-β, which require further research.

CONCLUSION

Several molecular biomarkers have been identified for the tailored treatment of mCRC patients and multiple efforts are currently ongoing to increase the therapeutic options. In the era of precision medicine, molecular-biology-driven treatment is the key to impro patient selection and patient outcomes. Further research and large phase III trials are required to ameliorate the therapeutic management of these patients.

RET fusions in solid tumors

The RET proto-oncogene has been well-studied. RET is involved in many different physiological and developmental functions. When altered, RET mutations influence disease in a variety of organ systems from Hirschsprung's disease and multiple endocrine neoplasia 2 (MEN2) to papillary thyroid carcinoma (PTC) and non-small cell lung cancer (NSCLC). Changes in RET expression have been discovered in 30-70% of invasive breast cancers and 50-60% of pancreatic ductal adenocarcinomas in addition to colorectal adenocarcinoma, melanoma, small cell lung cancer, neuroblastoma, and small intestine neuroendocrine tumors. RET mutations have been associated with tumor proliferation, invasion, and migration. RET fusions or rearrangements are somatic juxtapositions of 5' sequences from other genes with 3' RET sequences encoding tyrosine kinase. RET rearrangements occur in approximately 2.5-73% of sporadic PTC and 1-3% of NSCLC patients. The most common RET fusions are CDCC6-RET and NCOA4-RET in PTC and KIF5B-RET in NSCLC. Tyrosine kinase inhibitors are drugs that target kinases such as RET in RET-driven (RET-mutation or RET-fusion-positive) disease. Multikinase inhibitors (MKI) target various kinases and other receptors. Several MKIs are FDA-approved for cancer therapy (sunitinib, sorafenib, vandetanib, cabozantinib, regorafenib, ponatinib, lenvatinib, alectinib) and non-oncologic disease (nintedanib). Selective RET inhibitor drugs LOXO-292 (selpercatinib) and BLU-667 (pralsetinib) are also undergoing phase I/II and I clinical trials, respectively, with preliminary results demonstrating partial response and low incidence of serious adverse events. RET fusions provide a viable therapeutic target for oncologic treatment, and further study is warranted into the prevalence and pathogenesis of RET fusions as well as development of current and new tyrosine kinase inhibitors.

Targeting Receptor Kinases in Colorectal Cancer

Colorectal cancer is the third most common malignancy in men and the second most common cancer in women. Despite the success of screening programs and the development of adjuvant therapies, the global burden of colorectal cancer is expected to increase by 60% to more than 2.2 million new cases and 1.1 million deaths by 2030. In recent years, a great effort has been made to demonstrate the utility of protein kinase inhibitors for cancer treatment. Considering this heterogeneous disease is defined by mutations that activate different Receptor Tyrosine Kinases (RTKs) and affect downstream components of RTK-activated transduction pathways, in this review we analyze the potential utility of different kinase inhibitors for colorectal cancer treatment.