Efficacy of immunotherapy in RET fusion-positive NSCLC: A meta-analysis.

Background: The Rearranged during Transfection (RET) gene represents a rare driver mutation in non-small cell lung cancer (NSCLC) occurring in only 1 %-2 % of cases, with implications in targeted carcinogenesis. Despite the significant efficacy demonstrated by immunotherapy in advanced NSCLC with wild-type driver genes, its validation in RET fusion-positive patients is yet to be established. Objectives: This meta-analysis aims to systematically evaluate the effectiveness of immunotherapy in patients with RET fusion-positive NSCLC. Data sources: and Methods: PubMed and Web of Science databases were systematically searched for relevant studies. Outcomes including objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) were extracted for further analysis. Results: Ten real-world evidence (RWE) studies involving 7145 patients were enrolled in this meta-analysis. In terms of tumor response, the pooled ORR and DCR were 24.0 % and 61.0 %, respectively. Regarding survival analysis, the pooled median PFS and median OS were 4.17 months [95 % confidence interval (CI): 3.40-5.02) and 17.22 months (95 % CI: 11.58-23.91)], respectively. Subgroup analyses showed that immunotherapies plus chemotherapy were superior to single-immunotherapy in terms of ORR, DCR, and median PFS, which were 43 % (95 % CI: 31%-55 %) vs. 17 % (95 % CI: 11%-25 %), 74 % (95 % CI: 60%-84 %) vs. 45 % (95 % CI: 31%-59 %) and 6.69 months (95 % CI: 4.91-8.93) vs. 2.96 months (95 % CI: 2.25-3.78), respectively. Conclusions: To date, RET fusions appear to be associated with poor response to immunotherapy in NSCLC patients, and immunotherapy combined with chemotherapy seems to offer greater clinical benefits than mono-immunotherapy.

A Locally Advanced NSCLC Patient Harboring a Rare KIF13A-RET Fusion Benefited from Pralsetinib: A Case Report.

The application of adjuvant treatment has significantly enhanced the survival of patients with resectable non-small cell lung cancer (NSCLC) carrying driver gene mutations. However, adjuvant-targeted therapy remains controversial for some NSCLC patients carrying rare gene mutations such as RET, as there is currently a lack of confirmed randomized controlled trials demonstrating efficacy. In this report, we describe the case of a 58-year-old man with stage IIIA NSCLC who underwent complete lobectomy with selective lymph node dissection. Postoperative next-generation sequencing revealed that the patient harbored a rare KIF13A-RET fusion. The patient elected to receive adjuvant treatment with pralsetinib monotherapy and underwent serial circulating tumor DNA (ctDNA) monitoring after surgery. During follow-up, despite experiencing dose reduction and irregular medication adherence, the patient still achieved a satisfactory disease-free survival (DFS) of 27 months. Furthermore, ctDNA predicted tumor recurrence 4 months earlier than imaging techniques. The addition of bevacizumab to the original regimen upon recurrence continued to be beneficial. Pralsetinib demonstrated promising efficacy as adjuvant therapy, while ctDNA analysis offered a valuable tool for early detection of tumor recurrence. By leveraging targeted therapies and innovative monitoring techniques, we aim to improve outcomes and quality of life for NSCLC patients in the future.

A case of organizing pneumonia in rearranged during transfection fusion-positive lung adenocarcinoma treated with selpercatinib.

Selpercatinib is the first targeted therapy for rearranged during transfection (RET) fusion-positive unresectable non-small-cell lung cancer (NSCLC). The main adverse effects of selpercatinib include hypertension, liver dysfunction, diarrhea, and QT prolongation on electrocardiograms. However, instances of drug-induced interstitial lung disease (DI-ILD) are infrequently reported. We describe the first case of a patient with RET fusion-positive NSCLC treated with selpercatinib who developed DI-ILD, confirmed pathologically. The patient, a 72-year-old woman, initiated selpercatinib treatment following the postoperative recurrence of lung adenocarcinoma. After 15 months of treatment, computed tomography scans revealed multiple infiltrates and ground-glass opacities in both lungs. A thoracoscopic lung biopsy identified organizing pneumonia, attributed to DI-ILD caused by selpercatinib. Although she was asymptomatic, the patient's selpercatinib treatment was discontinued, leading to a gradual improvement in the lung infiltrates. Despite the lack of detailed reports, DI-ILD with selpercatinib represents a potentially serious adverse event and should be approached with caution.

LIBRETTO-431: Confirming the Superiority of Selpercatinib to Chemotherapy and the Lack of Efficacy of Immune Checkpoint Inhibitors in Advanced RET Fusion-Positive (RET+) NSCLC, Another Unique Never-Smoker Predominant Molecular Subtype of NSCLC.

Selpercatinib, a potent and highly selective RET kinase inhibitor with significant CNS activity, has recently gained US approval for the treatment of NSCLC harboring RET fusions (RET+) based on a large-scale single-arm study. The LIBRETTO-431 trial was the global pivotal registration phase 3 trial comparing selpercatinib to platinum-based chemotherapy with or without pembrolizumab as the first-line treatment of patients with advanced RET+ NSCLC. Never-smokers constituted 67.4% of the RET+ NSCLC patients enrolled. KIF5B-RET made up the vast majority (77%) of the RET+ fusion variant with known fusion partner. The results of this study demonstrated significant improvement in progression-free survival (PFS) benefit as well as impressive intracranial disease response in participants treated with selpercatinib as compared to those treated with chemotherapy, with a HR [hazard ratio] of 0.46 (95% CI 0.33-0.70; P < 0.001) for the intention-to-treat (ITT)-pembrolizumab group and HR of 0.46 (95% CI 0.31-0.70, P < 0.001) for the overall ITT-group of patients. The addition of pembrolizumab to platinum/pemetrexed chemotherapy resulted in numerically identical PFS (11.2 months). These results point to selpercatinib's superiority to traditional chemotherapy regimens in the treatment of NSCLC harboring RET fusions and add to literature on the salience of targeted precision oncology and lack of efficacy of immune checkpoint inhibitor in NSCLC patients with never-smoker predominant actionable driver mutations. RET+ NSCLC should be added to the list of molecular subtypes (EGFR+, ALK+, ROS1+) of NSCLC to be excluded in chemoimmunotherapy trial.

Multicenter evaluation of an automated, multiplex, RNA-based molecular assay for detection of ALK, ROS1, RET fusions and MET exon 14 skipping in NSCLC.

The current study assessed the performance of the fully automated RT-PCR-based Idylla™ GeneFusion Assay, which simultaneously covers the advanced non-small cell lung carcinoma (aNSCLC) actionable ALK, ROS1, RET, and MET exon 14 rearrangements, in a routine clinical setting involving 12 European clinical centers. The Idylla™ GeneFusion Assay detects fusions using fusion-specific as well as expression imbalance detection, the latter enabling detection of uncommon fusions not covered by fusion-specific assays. In total, 326 archival aNSCLC formalin-fixed paraffin-embedded (FFPE) samples were included of which 44% were resected specimen, 46% tissue biopsies, and 9% cytological specimen. With a total of 179 biomarker-positive cases (i.e., 85 ALK, 33 ROS1, 20 RET fusions and 41 MET exon 14 skipping), this is one of the largest fusion-positive datasets ever tested. The results of the Idylla™ GeneFusion Assay were compared with earlier results of routine reference technologies including fluorescence in situ hybridization, immunohistochemistry, reverse-transcription polymerase chain reaction, and next-generation sequencing, establishing a high sensitivity/specificity of 96.1%/99.6% for ALK, 96.7%/99.0% for ROS1, 100%/99.3% for RET fusion, and 92.5%/99.6% for MET exon 14 skipping, and a low failure rate (0.9%). The Idylla™ GeneFusion Assay was found to be a reliable, sensitive, and specific tool for routine detection of ALK, ROS1, RET fusions and MET exon 14 skipping. Given its short turnaround time of about 3 h, it is a time-efficient upfront screening tool in FFPE samples, supporting rapid clinical decision making. Moreover, expression-imbalance-based detection of potentially novel fusions may be easily verified with other routine technologies without delaying treatment initiation.

Primary Resistance to RET Inhibition in a RET Fusion-Positive Pancreatic Neuroendocrine Carcinoma.

We present a 54-year-old White male with a diagnosis of stage IV pancreatic neuroendocrine carcinoma. Next-generation sequencing of the tumor/blood identified a complex tumor genome, which included a rearranged during transfection (RET) gene fusion. The patient initially received cytotoxic chemotherapy with a significant radiographic response. After 4 cycles of chemotherapy, the patient was transitioned to a clinical trial using selpercatinib, a RET inhibitor, as maintenance therapy. Unfortunately, our patient developed progression of disease at the first treatment monitoring scan. Our patient suffered primary resistance to RET-targeted therapy. Proposed mechanisms of resistance include intrinsic resistance of the nuclear receptor co-activator 4-RET fusion to RET inhibition, the RET fusion representing a passenger alteration to another tumorigenic driver pathway and/or decreased efficacy of RET inhibition after platinum-based chemotherapy. Our patient's clinical course highlights the fact that "actionable" genomic alterations do not always equate to patient benefit.

Cabozantinib Response in a Patient With NSCLC Harboring Both MET Exon 14 Skipping Mutation and Secondary RET Fusion: A Case Report.

MET exon 14 skipping mutation has emerged as a new oncogenic driver in NSCLC with available targeted therapies, including Food and Drug Administration-approved inhibitors capmatinib and tepotinib. Potential resistance mechanisms are beginning to be described and include several on-target and off-target mutations. Here, we report an emergent secondary RET fusion in a patient with a primary MET exon 14 skipping mutation that progressed on capmatinib after the initial response. Subsequently, this patient received both a RET inhibitor (selpercatinib) followed by another MET-targeted treatment (tepotinib) without clinical benefit. Thereafter, cabozantinib, a multikinase inhibitor with activity against RET and MET was started with a rapid clinical and radiologic benefit.

Concurrent KRAS p.G12C mutation and ANK3::RET fusion in a patient with metastatic colorectal cancer: a case report.

BACKGROUND: Colorectal cancer (CRC) frequently involves mutations in the KRAS gene, impacting therapeutic strategies and prognosis. The occurrence of KRAS mutations typically precludes the presence of RET fusions, with current medical literature suggesting a mutual exclusivity between these two genetic alterations. We present a unique case that challenges this notion. CASE PRESENTATION: An 85-year-old female with metastatic CRC was found to have a combination of genetic anomalies that is to the best of our knowledge not yet described in the medical literature: a KRAS p.G12C mutation, associated with oncogenesis and treatment resistance, and an ANK3::RET fusion, an infrequent but targetable mutation in CRC. This molecular profile was uncovered through comprehensive genomic sequencing after the patient experienced metachronous tumor dissemination. The presence of both genetic events complicates the treatment approach. CONCLUSIONS: The identification of both a KRAS p.G12C mutation and an ANK3::RET fusion in the same CRC patient adds a new layer to the oncogenic landscape and treatment considerations for CRC. It highlights the intricate decision-making required in the era of precision medicine, where targeted therapies must be carefully chosen and potentially combined to combat complex genetic profiles. The case emphasizes the urgency of investigating the clinical effects of concurrent or sequential use of KRAS p.G12C and RET inhibitors to inform future therapeutic guidelines and improve patient outcomes in similar cases.

Real-world outcomes of chemoimmunotherapy and selective RET inhibitors in Chinese patients with RET fusion-positive non-small cell lung cancer.

Background: Rearranged during transfection (RET) gene fusion is a target for non-small cell lung cancer (NSCLC) treatment, and RET inhibitors are approved for advanced NSCLC. The role of immune checkpoint inhibitors (ICIs) in RET fusion-positive NSCLC remains controversial. This retrospective study analyzed the efficacy of ICIs and RET inhibitors in Chinese patients with RET fusion-positive NSCLC. Methods: Data from patients diagnosed with advanced NSCLC harboring RET fusion from Jan 2017 to Sep 2021 were analyzed. Clinicopathological characteristics and outcomes of ICIs and RET inhibitors treatments were collected. Results: Seventy-five patients with RET fusion-positive advanced NSCLC were identified. The median age of patients was 57 years, half of the patients were female (50.3%), and most were non-smokers or light smokers (72%). Of the cancer types diagnosed in study patients, the KIF5B-RET fusion subtype accounted for 73.3% (55/75), twelve patients (16%) had CCDC6-RET fusion, and three (4%) had NCOA4-RET fusion. Sixteen patients were treated with ICIs. In previously untreated patients, we observed an objective response rate (ORR) of 71.4% and median progression free survival (PFS) of 7.5 months in seven assessable patients. Of four patients with PD-L1 overexpression (>50%) one received pembrolizumab and the other three patients received pemetrexed, carboplatin, and pembrolizumab or camrelizumab. In these patients, the ORR was 75% and disease control rate was 100%. Fifteen patients received selective RET inhibitors (pralsetinib and selpercatinib), resulting in an ORR of 53.3% (8/15) and median PFS of 10.0 months (95% CI 5.2-14.9). Conclusions: ICIs for PD-L overexpression and treatment naive patients offer comparable benefits for RET fusion-positive NSCLC, warranting further investigation.

Case report: First evidence of impressive efficacy of modulated dose selpercatinib in a young Caucasian with ANK3-RET fusion-positive NSCLC.

Over the past decade, molecular characterization has led to change the management of advanced non-small cell lung cancer (NSCLC) harboring driver mutations. Rearranged during transfection (RET) gene fusions, occurring in 1% to 2% of NSCLC, have emerged as an oncogenic druggable target. Systemic targeted therapies with highly selective RET inhibitors (RETi), selpercatinib and pralsetinib, represent a recent clinical breakthrough. While the development of RETi has improved survival, with their increasing use, it is crucial to be aware of the risks of rare but serious adverse events (AEs). A particular challenge for clinicians in applying targeted therapies is not only diagnosing but also interpreting rare mutations. Herein, we report a case of a 43-year-old Caucasian advanced NSCLC patient diagnosed with a rare RET gene fusion, ANK3::RET, identified with Next Generation Sequencing (NGS). Selpercatinib has been initiated at the recommended initial dose after one incomplete chemotherapy cycle due to a severe infusion reaction, but it subsequently required a dose adjustment following grade 3 (G3) AEs. During treatment, we used a particular selpercatinib dosage (160 mg in the morning and 80 mg in the evening) with good tolerance and without compromising effectiveness. Our finding broadens the range of RET fusion types in not-Asian NSCLC. To the best of our knowledge, our case demonstrates, for the first time, a clinical and radiological response to frontline highly selective RETi selpercatinib, expanding the spectrum of potential oncogenic RET fusion partners in newly diagnosed NSCLC patients. Furthermore, to our knowledge, this is the first case describing a RET fusion-positive (RET+) NSCLC patient treated with a modified selpercatinib dosage outside the drug data sheet and demonstrating a safe and effective use.

Impact of tissue-agnostic approvals on management of primary brain tumors.

Novel tissue-agnostic therapeutics targeting driver mutations in tumor cells have been recently approved by FDA, driven by basket trials that have demonstrated their efficacy and safety across diverse tumor histology. However, the relative rarity of primary brain tumors (PBTs) has limited their representation in early trials of tissue-agnostic medications. Thus, consensus continues to evolve regarding utility of tissue-agnostic medications in routine practice for PBTs, a diverse group of neoplasms characterized by limited treatment options and unfavorable prognoses. We describe current and potential impact of tissue-agnostic approvals on management of PBTs. We discuss data from clinical trials for PBTs regarding tissue-agnostic targets, including BRAFV600E, neurotrophic tyrosine receptor kinase (NTRK) fusions, microsatellite instability-high (MSI-High), mismatch repair deficiency (dMMR), and high tumor mutational burden (TMB-H), in context of challenges in managing PBTs. Described are additional tissue-agnostic targets that hold promise for benefiting patients with PBTs, including RET fusion, fibroblast growth factor receptor (FGFR), ERBB2/HER2, and KRASG12C, and TP53Y220C.

Pralsetinib in patients with RET fusion-positive non-small-cell lung cancer: A plain language summary of the ARROW study.

WHAT IS THIS SUMMARY ABOUT?: This is a summary of a research study called ARROW, which tested a medicine called pralsetinib in patients with non-small cell lung cancer (NSCLC), thyroid cancer, and other advanced solid tumours caused by a change in a gene called RET. For the purposes of this summary, only patients with NSCLC with a change in RET called fusion (RET fusion+) are highlighted. WHAT WERE THE RESULTS?: In total, 281 patients with RET fusion+ NSCLC had taken part in this study across the USA, Europe, and Asia. Patients were asked to take four pills (adding up to 400 mg) of pralsetinib each day and were checked for any changes in their tumours, as well as for any side effects. After an average of 8 months of treatment with pralsetinib, 72% of previously untreated patients and 59% of patients who had previously received chemotherapy had considerable shrinkage of their tumours. Among 10 patients with tumours which had spread to the brain (all of whom had received previous treatments), 70% had their tumours shrink greatly in the brain after treatment with pralsetinib. On average, patients lived with little to no tumour growth for 16 months. In previously untreated patients, the most common severe side effects that were considered related to pralsetinib treatment were decreased white blood cells (neutrophils and lymphocytes), increased blood pressure, and an increase in a blood protein called creatine phosphokinase. In previously treated patients, the severe side effects were decreased white blood cells (neutrophils, lymphocytes, and leukocytes), increased blood pressure, and low levels of red blood cells. In both untreated and previously treated patients, the most common severe side effects that required hospital attention were lung inflammation/swelling causing shortness of breath (pneumonitis) and lung infection (pneumonia). WHAT DO THE RESULTS MEAN?: Overall, the ARROW study showed that pralsetinib was effective in shrinking tumours in patients with RET fusion+ NSCLC regardless of previous treatment history. The recorded side effects were expected in patients receiving this type of medicine. Clinical Trial Registration: NCT03037385 (ARROW) (ClinicalTrials.gov).

Salvage Therapy With Selpercatinib for RET-Rearranged NSCLC With Pralsetinib-Related Pneumonitis and Leptomeningeal Disease: A Case Report.

Selpercatinib and pralsetinib are RET inhibitors with substantial activity in advanced RET-rearranged NSCLC. We present a case of pralsetinib-related pneumonitis and leptomeningeal and brain metastases progression during treatment suspension for pneumonitis. During recovery, selpercatinib administration led to rapid neurologic response and complete intracranial response and allowed pneumonitis resolution. This case supports the safety of selpercatinib in patients with pneumonitis on pralsetinib and highlights its marked efficacy in leptomeningeal disease.

Comprehensive next-generation sequencing reveals double primary colorectal carcinoma missed by diagnostic imaging: A case report.

BACKGROUND: Multiple primary colorectal carcinoma (MPCC) is a rare clinical disease, which is challenging to differentiate from metastatic disease using histopathological methods. Next-generation sequencing (NGS) has been employed to identify multiple primary cancers. CASE SUMMARY: This study a rare case of a 63-year-old male patient diagnosed with MPCC by targeted NGS, which was initially missed by radiological evaluation. The patient was found to have two tumors located on the surface of the colorectum which had distinct genomic alterations. Based on wild-type KRAS detected in the unresected tumor, the patient benefited from the epidermal growth factor receptor (EGFR) inhibitor cetuximab treatment, but developed novel mutations including KIF5B-RET fusion, which provides a possible resistance mechanism to anti-EGFR therapy. CONCLUSION: Our case highlights the necessity of using genetic testing for primary tumor diagnosis and the application of serial plasma circulating tumor DNA profiling for dynamic disease monitoring.

Selpercatinib for adult patients with locally advanced or metastatic RET-altered solid tumors.

INTRODUCTION: The rearranged during transfection (RET) mutation is an oncogene driver for the development of cancer. Selpercatinib is a highly selective RET inhibitor that has demonstrated anti-tumor activity in RET-mutated cancers. Selpercatinib is approved for use in RET fusion-positive non-small-cell lung cancer (NSCLC), RET-mutated medullary thyroid cancer, RET fusion-positive thyroid cancer, and RET fusion-positive solid tumors. AREAS COVERED: This review summarizes the pharmacology, efficacy, safety, and resistance mechanism of selpercatinib. EXPERT OPINION: Selpercatinib has demonstrated durable responses with a favorable safety profile making it an excellent treatment option for RET-mutated cancers. Clinical trials are currently underway to determine the optimal sequencing of selpercatinib in RET fusion-positive lung and RET-mutated medullary thyroid cancer in the first-line setting compared to the current standard of care. Selpercatinib has shown promising anti-tumor activity in various RET-altered solid tumors opening a new treatment option for these patients.

Selpercatinib and capmatinib combination promotes sustained complete response in novel ISOC1-RET fusion lung cancer after resistance to RET inhibitor via MET amplification: Case Report.

RET fusions occur in 1-2% of non-small cell lung cancer. Selpercatinib and pralsetinib are selective RET inhibitors with significant improvement of outcome in patients with tumor harboring RET fusion; however, resistance mechanisms appear frequently, mainly driven by MAPK pathway bypass, secondary RET mutations, or in 5% via MET amplification. Co-inhibition of RET and MET is a compelling strategy for overcoming MET-dependent resistance to RET inhibitors and potentially other inhibitors. To our knowledge, this is the first report of a novel ISOC1-RET fusion lung cancer with a durable complete response to selpercatinib, with resistance via MET amplification, which was overcome by the successful combination of selpercatinib and capmatinib.

Expert consensus on the diagnosis and treatment of RET gene fusion non-small cell lung cancer in China.

The rearranged during transfection (RET) gene is one of the receptor tyrosine kinases and cell-surface molecules responsible for transmitting signals that regulate cell growth and differentiation. In non-small cell lung cancer (NSCLC), RET fusion is a rare driver gene alteration associated with a poor prognosis. Fortunately, two selective RET inhibitors (sRETi), namely pralsetinib and selpercatinib, have been approved for treating RET fusion NSCLC due to their remarkable efficacy and safety profiles. These inhibitors have shown the ability to overcome resistance to multikinase inhibitors (MKIs). Furthermore, ongoing clinical trials are investigating several second-generation sRETis that are specifically designed to target solvent front mutations, which pose a challenge for first-generation sRETis. The effective screening of patients is the first crucial step in the clinical application of RET-targeted therapy. Currently, four methods are widely used for detecting gene rearrangements: next-generation sequencing (NGS), reverse transcription-polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), and immunohistochemistry (IHC). Each of these methods has its advantages and limitations. To streamline the clinical workflow and improve diagnostic and treatment strategies for RET fusion NSCLC, our expert group has reached a consensus. Our objective is to maximize the clinical benefit for patients and promote standardized approaches to RET fusion screening and therapy.

Patient-reported outcomes following selpercatinib treatment in Chinese patients with advanced RET fusion-positive non-small-cell lung cancer and thyroid cancer, and RET-mutant medullary thyroid cancer in the phase II LIBRETTO-321 trial.

Background: Patient-reported outcomes (PROs) are increasingly becoming an important part of clinical trials as they are helpful in analyzing the safety and efficacy of treatment in chronic diseases like cancer. Objectives: We report PROs and health-related quality of life (HRQoL) with selpercatinib treatment among Chinese patients with rearranged in transfection (RET) fusion-positive non-small-cell lung cancer (NSCLC), RET fusion-positive thyroid cancer (TC), and RET-mutant medullary TC (MTC) as an exploratory analysis of the LIBRETTO-321 trial. Design: A total of 77 patients (47 RET fusion-positive NSCLC, 1 RET fusion-positive TC, and 29 RET-mutant MTC) were enrolled. Compliance for European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core 30 (QLQ-C30) was 100% at baseline and >90% at each time point. Methods: PROs were assessed using the EORTC QLQ-C30, and a bowel diary assessment for MTC patients with baseline diarrhea using the Systemic Therapy-Induced Diarrhea Assessment Tool. Data were collected at pre-dose; every 8 weeks from cycle 3; and every 12 weeks after cycle 13. A >10-point change from baseline was considered clinically meaningful. PRO changes were summarized through cycle 13. Results: Most patients with NSCLC or MTC showed improvement or remained stable on the global health status and functional subscales. For global health status, 47.4% of NSCLC and MTC patients showed definite improvement with only 19.7% showing definite worsening. For functional subscales, less than 30% of the patients showed definite worsening. For symptom subscales, more than 64% of the patients either improved or remained stable for the symptoms. For MTC patients with bowel diary assessment (n = 5), there was no severity or worsening from baseline in the diarrheal episodes observed during treatment with selpercatinib. Conclusion: The study demonstrated favorable PROs in Chinese patients with RET fusion-positive NSCLC, TC, and RET-mutant MTC treated with selpercatinib. HRQoL was improved or stable as assessed by EORTC QLQ-30. Trail registration: This study was registered at ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT04280081) ClinicalTrials.gov Identifier: NCT04280081.

RET-Altered Cancers-A Tumor-Agnostic Review of Biology, Diagnosis and Targeted Therapy Activity.

RET alterations, such as fusions or mutations, drive the growth of multiple tumor types. These alterations are found in canonical (lung and thyroid) and non-canonical (e.g., gastrointestinal, breast, gynecological, genitourinary, histiocytic) cancers. RET alterations are best identified via comprehensive next-generation sequencing, preferably with DNA and RNA interrogation for fusions. Targeted therapies for RET-dependent cancers have evolved from older multikinase inhibitors to selective inhibitors of RET such as selpercatinib and pralsetinib. Prospective basket trials and retrospective reports have demonstrated the activity of these drugs in a wide variety of RET-altered cancers, notably those with RET fusions. This paved the way for the first tumor-agnostic selective RET inhibitor US FDA approval in 2022. Acquired resistance to RET kinase inhibitors can take the form of acquired resistance mutations (e.g., RET G810X) or bypass alterations.