Targeting RET in Patients With RET-Rearranged Lung Cancers: Results From the Global, Multicenter RET Registry

Treatment of RET/ALK comutated advanced lung large cell neuroendocrine carcinoma: a case report and literature review

The prognosis of advanced lung large-cell neuroendocrine carcinoma is poor, and the efficacy of targeted therapy is still being explored. A case of RET fusion mutation combined with ALK rearrangement positive advanced lung complex large cell neuroendocrine carcinoma was reported. The patient developed intrapulmonary and bone metastases 8 months after chemotherapy after lung cancer surgery, RET fusion mutations were detected by genetic testing, and intracranial progression occurred 1 year after pilatinib was applied. The comutation of RET and ALK was detected by genetic testing, and the pulmonary progression occurred 2 months after the application of aletinib, after being treated with pilatinib and aletinib, he progressed again in 9 months. We point out that large cell neuroendocrine carcinoma complex patients with RET gene mutation can benefit from targeted therapy, and when drug resistance is accompanied by ALK comutation, the patient can benefit from the treatment of the aletinib combined with pilatinib targeted therapy and the side effect is slight. At the same time, we further explore the resistance mechanism of targeted therapy in lung cancer.

AP1-mediated reprogramming of EGFR expression triggers resistance to BLU-667 and LOXO-292 in RET-rearranged tumors

BACKGROUND

Non-small cell lung cancer (NSCLC) is a significant global health challenge, with 2% of cases fuelled by RET rearrangements. RET inhibitors (RETi) have revolutionized treatment for these patients, but resistance remains an important clinical challenge limiting therapy effectiveness. This study investigated the mechanisms underlying resistance to RETi.

METHODS

NSCLC cells were exposed to increasing doses of RETi (pralsetinib/BLU-667 and selpercatinib/LOXO-292) to generate resistant cells. RNA-Sequencing analysis identified differentially expressed genes in resistant versus sensitive cells, followed by in vitro and in vivo functional assays to explore novel therapeutic strategies. Additionally, tumor biopsies from RET-rearranged NSCLC patients who exhibited cancer progression on RET inhibitor therapy were analyzed.

RESULTS

RNA-sequencing analysis revealed the upregulation of the EGFR signaling pathway and hyperactivation of AP1 complex members in resistant cells compared to sensitive cells. Silencing of EGFR and AP1 complex members significantly reversed drug resistance, whereas EGFR overexpression reduced the sensitivity of parental Lc2/AD cells to RET inhibitors. Furthermore, the combination of RET and EGFR inhibitors showed synergistic antitumor activity in vitro and hindered tumor growth in mouse models with resistant cell xenografts. Notably, we observed a significant increase in EGFR expression in tumor biopsies from NSCLC patients treated with RET inhibitors who experienced disease progression, further validating the clinical relevance of our findings.

CONCLUSIONS

This study elucidates EGFR's role in mediating resistance to RET inhibitors in NSCLC patients. These findings offer insights into therapeutic adaptation and explore personalized combinations of RET and EGFR inhibitors for improved clinical outcomes.

Clinical characterization and therapeutic targeting of fusion genes in oncology

Gene fusions represent important oncogenic driver mutations resulting in aberrant cellular signaling. In up to 17% of all solid tumors at least one gene fusion can be identified. Precision therapy targeting fusion gene signaling has demonstrated effective clinical benefit. Advancements in clinically relevant next-generation sequencing and bioinformatic techniques have enabled expansion of therapeutic opportunity to subpopulations of patients with fusion gene expression. Clinically, tyrosine inhibitors have shown efficacy in treating fusion gene expressing cancers. Fusion genes are also clonal mutations, meaning it is a personal cancer target involving all cancer cells of that patient, not just a subpopulation of cancer cells within the cancer mass. Thus, both fusion signal disruption and immune signal targeting are effective therapeutic directions. This review discusses fusion gene targeting, therapeutic resistance, and molecular biomarkers.

Next-generation sequencing for guiding matched targeted therapies in people with relapsed or metastatic cancer

BACKGROUND

Matched targeted therapies (MTT) given alone or in combination with systemic anti-cancer therapies have delivered proven survival benefit for many people with newly diagnosed cancer. However, there is little evidence of their effectiveness in the recurrent or late-stage setting. With this uncertainty, alongside the perception that late-stage cancers are too genetically heterogenous or too mutationally diverse to benefit from matched targeted therapies, next-generation sequencing (NGS) of tumours in people with refractory cancer remains a low priority. As a result, next-generation sequencing testing of recurrent or late-stage disease is discouraged. We lack evidence to support the utility of next generation sequencing in guiding matched targeted therapies in this setting.

OBJECTIVES

To evaluate the benefits and harms of matched targeted therapies in people with advanced cancers in randomised controlled trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, ClinicalTrials.gov, and the World Health Organisation International Clinical Trials Registry Platform (WHO-ICTRP) search portal up to 30th October 2024. We also screened reference lists of included studies and also the publications that cited these studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that had enroled participants with advanced/refractory solid or haematological cancers who had progressed through at least one line of standard anti-cancer systemic therapy. To be eligible, all participants should have received matched targeted therapy based on next-generation sequencing carried out on their tumour (tumour tissue, blood or bone marrow).

DATA COLLECTION AND ANALYSIS

We systematically searched medical databases (e.g. MEDLINE, Embase) and trial registers for randomised controlled trials (RCTs). Outcomes of interest were progression-free survival (PFS), overall survival (OS), overall response rates (ORR), serious (grade 3 or 4) adverse events (AEs) and quality of life (QOL). We used a random-effects model to pool outcomes across studies and compared predefined subgroups using interaction tests. Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessment of certainty was used to evaluate the quality of evidence.

MAIN RESULTS

We identified a total of 37 studies, out of which 35 studies (including 9819 participants) were included in the meta-analysis. All included studies compared a matched targeted therapy intervention to standard-of-care treatment, non-matched targeted therapies or no treatment (best supportive care): Matched targeted therapy versus standard-of-care treatment Matched targeted therapy (MTT) compared with standard systematic therapy probably reduces the risk of disease progression by 34% (hazard ratio (HR) = 0.66, 95% confidence interval (CI) 0.59 to 0.74; 14 studies, 3848 participants; moderate-certainty evidence). However, MTT might have little to no difference in risk of death (HR = 0.85, 95% CI 0.75 to 0.97; 14 studies, 3848 participants; low-certainty evidence) and may increase overall response rates (low-certainty evidence). There was no clear evidence of a difference in severe (grade 3/4) adverse events between matched targeted therapy and standard-of-care treatment (low-certainty evidence). There was limited evidence of a difference in quality of life between groups (very low-certainty of evidence). Matched targeted therapy in combination with standard-of-care treatment versus standard-of-care treatment alone Matched targeted therapy in combination with standard-of-care treatment compared with standard-of-care treatment alone probably reduces the risk of disease progression by 39% (HR = 0.61, 95% CI 0.53-0.70, 14 studies, 2,637 participants; moderate-certainty evidence) and risk of death by 21% (HR = 0.79, 95% CI 0.70 to 0.89; 11 studies, 2575 participants, moderate-certainty evidence). The combination of MTT and standard-of-care treatment may also increase overall response rates (low-certainty evidence). There was limited evidence of a difference in the incidence of severe adverse events (very low-certainty evidence) and quality of life between the groups (very low-certainty of evidence). Matched targeted therapy versus non-matched targeted therapy Matched targeted therapy compared with non-matched targeted therapy probably reduces the risk of disease progression by 24% (HR = 0.76, 95% CI 0.64 to 0.89; 3 studies, 1568 participants; moderate-certainty evidence) and may reduce the risk of death by 25% (HR = 0.75, 95% CI 0.65 to 0.86, 1307 participants; low-certainty evidence). There was little to no effect on overall response rates between MTT and non-MTT. There was no clear evidence of a difference in overall response rates (low-certainty evidence) and severe adverse events between MTT and non-MTT (low-certainty evidence). None of the studies comparing MTT and non-MTT reported quality of life. Matched targeted therapy versus best supportive care Matched targeted therapy compared with the best supportive care (BSC) i.e. no active treatment probably reduces the risk of disease progression by 63% (HR 0.37, 95% CI 0.28 to 0.50; 4 studies, 858 participants; moderate-certainty evidence). There was no clear evidence of a difference in overall survival between groups (HR = 0.88, 95% CI 0.73 to 1.06, 3 studies, 783 participants; low-certainty evidence). There was no clear evidence of a difference in overall response rates (very low-certainty of evidence) and incidence of severe adverse events (very low-certainty of evidence) between the groups. Quality of life was reported in a single study but did not provide composite scores. Risk of bias The overall risk of bias was judged low for eight studies, unclear for two studies, and the remaining 27 studies were high risk.

AUTHORS' CONCLUSIONS

Matched targeted therapies guided by next-generation sequencing in people with advanced cancer prolongs the time before cancer progresses compared to standard therapies. However, there is limited evidence to suggest that it prolongs overall survival, improves the quality of life or increases adverse events. Importantly, this review supports equitable access to next-generation sequencing technology for all people with advanced cancer and offers them the opportunity to access genotype-matched targeted therapies.

Treatment of non-small cell lung cancer with RET rearrangements

Aberrant activation of the RET oncogene by mutations or gene fusions drives various malignancies, including 1%-2% of all non-small cell lung cancers (NSCLCs) that harbor RET gene fusions. Initial attempts to target RET fusion-positive NSCLC with poorly selective multikinase RET inhibitors were associated with significant toxicities and limited efficacy. Two highly potent and selective RET small-molecule inhibitors, selpercatinib and pralsetinib, were granted accelerated approval for advanced RET fusion-positive NSCLC by the US Food and Drug Administration, and have been shown to be highly effective both in treatment-naive and previously treated patients with NSCLC. Selpercatinib has shown superiority over chemotherapy in a phase 3 study (LIBRETTO-431) in previously untreated patients with RET fusion-positive NSCLC, which established its place as the standard of care in this patient population. This review discusses the biology and clinical characteristics of RET-rearranged NSCLC and summarizes the evolution of treatment strategies, current understanding of mechanisms of resistance, and development of new-generation agents to overcome resistance.

Pan-Cancer Molecular Biomarkers: Practical Considerations for the Surgical Pathologist

Traditional anatomic pathologic classification of cancer is based on tissue of origin and morphologic and immunohistochemical characterization of the malignant cells. With the technological improvements of massively parallel or next-generation sequencing, oncogenic drivers that are shared across different tumor types are increasingly being identified and used as pan-cancer biomarkers. This approach is reflected in the growing list of Food and Drug Administration-approved tumor-agnostic therapies, including pembrolizumab in the setting of microsatellite instability and high tumor mutational burden, larotrectinib and entrectinib for solid tumors with NTRK fusions, and combined dabrafenib-trametinib for BRAF V600E-mutated neoplasms. Several other biomarkers are currently under investigation, including fibroblast growth factor receptor (FGFR), RET, and ROS1 fusions; ERBB2 amplification; and mutations in the AKT1/2/3, NF1, RAS pathway and (mitogen-activated protein kinase (MAPK) pathway. As molecular assays are increasingly incorporated into routine tumor workup, the emergence of additional pan-cancer biomarkers is likely to be a matter more of "when" than "if." In this review, we first explore some of the conceptual and technical considerations at the intersection of surgical and molecular pathology, followed by a brief overview of both established and emerging molecular pan-cancer biomarkers and their diagnostic and clinical applications.

Safety, pharmacokinetics and efficacy of HA121-28 in patients with advanced solid tumors and RET fusion-positive non-small-cell lung cancer: a multicenter, open-label, single-arm phase 1/2 trial

HA121-28, a promising multikinase inhibitor, mainly targets rearranged during transfection (RET) fusions and selectively targets vascular endothelial growth factor receptor-2, endothelial growth factor receptor, and fibroblast growth factor receptor 1-3. The safety, pharmacokinetics, and efficacy of HA121-28 were assessed in advanced solid tumors (phase 1, ClinicalTrials.gov NCT03994484) and advanced RET fusion-positive non-small-cell lung cancer (RET-TKI naive NSCLC, phase 2, ClinicalTrials.gov NCT05117658). HA121-28 was administered orally in doses range from 25 to 800 mg under the 21-day on/7-day off scheme for a 28-day cycle in phase 1 trial. The recommended dose identified in phase 1 (450 mg) was administered for patients during phase 2. The primary endpoints were the maximum tolerated dose (MTD) in phase 1 and the objective response rate (ORR) in phase 2. 162 patients were enrolled in phase 1 and 48 in phase 2. A total of 600 mg once daily was set as MTD. Across 100-800 mg, the exposure of HA121-28 increased in a dose-dependent manner. Consistent between both trials, diarrhea, rash, and prolonged QTc interval, were the most reported treatment-emergent adverse events. 40.0% (phase 1) and 62.5% (phase 2) patients experienced grade ≥3 treatment-related adverse events, respectively. The overall ORR was 26.8% and the median progression-free survival (PFS) was 5.5 months among 97 NSCLC patients with advanced RET fusion receiving a dose at ≥450 mg once daily. HA121-28 showed encouraging efficacy in advanced RET fusion NSCLC and its toxicity was tolerable in most patients. Nevertheless, cardiotoxicity is a notable concern that warrants careful attention.

Discovery of a Selective and Orally Bioavailable RET Degrader with Effectiveness in Various Mutations

The rearranged during transfection (RET) mutation such as the G810C mutation has significantly restricted the clinical application of selective RET inhibitors in the treatment of RET-driven cancers. This study designed and evaluated RET proteolysis targeting chimeras (PROTACs) based on selpercatinib (LOXO-292), identifying RD-23 as a potent and selective RET PROTAC. RD-23 effectively inhibited the proliferation of BaF3 cells with various RET mutations, showing IC50 values of 2.4 to 6.5 nM. It selectively induced degradation of the RETG810C mutation via the ubiquitin-proteasome system, with a DC50 (concentration causing 50% of protein degradation) value of 11.7 nM. Additionally, RD-23 exhibited oral bioavailability and superior antitumor effects compared to LOXO-292 in a Ba/F3-KIF5B-RETG810C xenograft mouse model. These results suggested that RD-23 is a promising candidate for treating RET-driven cancers.

Non-small cell lung cancer and the tumor microenvironment: making headway from targeted therapies to advanced immunotherapy

Over the past decades, significant progress has been made in the understanding of non-small cell lung cancer (NSCLC) biology and tumor progression mechanisms, resulting in the development of novel strategies for early detection and wide-ranging care approaches. Since their introduction, over 20 years ago, targeted therapies with tyrosine kinase inhibitors (TKIs) have revolutionized the treatment landscape for NSCLC. Nowadays, targeted therapies remain the gold standard for many patients, but still they suffer from many adverse effects, including unexpected toxicity and intrinsic acquired resistance mutations, which lead to relapse. The adoption of immune checkpoint inhibitors (ICIs) in 2015, has offered exceptional survival benefits for patients without targetable alterations. Despite this notable progress, challenges remain, as not all patients respond favorably to ICIs, and resistance to therapy can develop over time. A crucial factor influencing clinical response to immunotherapy is the tumor microenvironment (TME). The TME is pivotal in orchestrating the interactions between neoplastic cells and the immune system, influencing tumor growth and treatment outcomes. In this review, we discuss how the understanding of this intricate relationship is crucial for the success of immunotherapy and survey the current state of immunotherapy intervention, with a focus on forthcoming and promising chimeric antigen receptor (CAR) T cell therapies in NSCLC. The TME sets major obstacles for CAR-T therapies, creating conditions that suppress the immune response, inducing T cell exhaustion. To enhance treatment efficacy, specific efforts associated with CAR-T cell therapy in NSCLC, should definitely focus TME-related immunosuppression and antigen escape mechanisms, by combining CAR-T cells with immune checkpoint blockades.

Discovery of an Efficacious RET PROTAC Degrader with Enhanced Antiproliferative Activity against Resistant Cancer Cells Harboring RET Solvent-Front Mutations

Rearranged during transfection (RET) kinase is a validated therapeutic target for various cancers characterized by RET alterations. Although two selective RET inhibitors, selpercatinib and pralsetinib, have been approved by the FDA, acquired resistance through solvent-front mutations has been identified rapidly. Developing proteolysis targeting chimera (PROTAC) targeting RET mutations offers a promising strategy to combat drug resistance. Herein, we describe the design, synthesis, and evaluation of a series of RET PROTAC degraders. The representative compound QZ2135 (20) effectively degraded RET kinase and its resistant mutants, such as V804M and G810C/R. It also exhibited superior antiproliferative activity against Ba/F3 cells stably expressing oncogenic fusions of RET with solvent-front mutants, including G810C/R/S, compared to its parental inhibitor. Notably, QZ2135 demonstrated in vivo antitumor efficacy in a Ba/F3-KIF5B-RET-G810C xenograft mouse model. Together, this study provides a potential alternative strategy for overcoming acquired resistance to RET inhibitors mediated by solvent-front mutations.

Constructing and identifying an eighteen-gene tumor microenvironment prognostic model for non-small cell lung cancer

BACKGROUND

The tumor microenvironment (TME) plays a crucial role in tumorigenesis and tumor progression. This study aimed to identify novel TME-related biomarkers and develop a prognostic model for patients with non-small-cell lung cancer (NSCLC).

METHODS

After downloading and preprocessing data from The Cancer Genome Atlas (TCGA) data portal and Gene Expression Omnibus (GEO) datasets, we classified the molecular subtypes using the "NMF" R package. We performed survival analysis and quantified immune scores between clusters. A Cox proportional hazards model was then constructed, and its formula was produced. We assessed model performance and clinical utility. A prediction nomogram was also constructed and validated. Additionally, we explored the potential regulatory mechanisms of our TME gene signature using Gene Set Enrichment Analysis (GSEA).

RESULTS

From data processing and univariate Cox regression analysis, 57 TME-related prognostic genes were identified, and two significantly distinct clusters were established. Using Cox regression and Lasso regression, an 18-gene TME-related prognostic model was developed. Patients were stratified into high- and low-risk groups based on the risk score, with survival analysis showing that the low-risk group had significantly better outcomes than the high-risk group (P < 0.01). ROC curve analysis demonstrated strong predictive performance, with 1-year, 3-year, and 5-year AUC values ranging from 0.654 to 0.702 across different cohorts. The model accurately predicted survival outcomes across subgroups with varying clinical features, and its predictive accuracy was validated through a nomogram.

CONCLUSIONS

We developed a prognostic model based on TME-related genes in NSCLC. Our 18-gene TME signature can effectively predict the prognosis of NSCLC with high accuracy.

Case Report: Efficacy of anlotinib and sintilimab in treating lung adenocarcinoma with RET fusion and PD-L1 expression

We report a case of an advanced non-small cell lung cancer (NSCLC) patient with brain metastasis, RET fusion, and high expression of programmed death ligand 1 (PD-L1) at initial treatment. After receiving radiotherapy for the brain metastasis, the patient started with anlotinib and added immunotherapy with sintilimab. The patient had a good response to anlotinib and sintilimab treatment, tolerated the adverse reactions, and had a progression-free survival (PFS) of over 17 months. To the best of our knowledge, this is the first clinical case report in the literature describing the benefit of anlotinib and sintilimab treatment for non-small cell lung cancer with RET fusion and high PD-L1 expression. This study explores the biomarker selection for targeted therapy and combined immunotherapy in NSCLC patients.

Efficacy and safety of RET-TKI in advanced RET-rearranged non-small cell lung cancer in China: a real-world retrospective chart review

BACKGROUND

Selective RET inhibitors have been approved by the Chinese government for the treatment of RET-rearranged non-small cell lung cancer. This study aimed to illustrate the efficacy and safety of selective RET inhibitors in a real-world clinical context in China.

METHODS

Patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harboring RET rearrangement and receiving RET tyrosine kinase inhibitors (RET-TKI) in the real world were enrolled in this retrospective study. Clinical data, including baseline clinicopathological information, efficacy parameters such as objective response rate (ORR) and progression-free survival (PFS), and adverse events (AEs), were collected from the electronic medical record system. The pattern of treatment failure of first-line RET-TKI was also described.

RESULTS

Fifty-one patients were enrolled in this study. RET-TKI induced an ORR of 73.1% and a median PFS (mPFS) of 22.7 months (95%CI, 11.7-33.7) in the first-line setting. The ORR and mPFS were 58.3% and 17.7 months (95%CI, 9.1-26.2), 55.6% and 14.7 months (95%CI, 12.6-16.8) in the second-line and later-line settings, respectively. No significant difference was observed among different application lines with respect to the ORR (P = 0.534) or PFS (P = 0.795). In the first-line setting, RET-TKI significantly prolonged PFS compared to other regimens including chemotherapy-based regimens, multikinase inhibitors and other systemic regimens without chemotherapy (P < 0.05). Poor ECOG performance status was related to shorter PFS (P = 0.018). The most common AEs of grade 3 or worse were a decreased neutrophil count (11.4%) and anemia (11.4%). No new AEs or grade 5 AEs were observed. Brain metastasis was one of the most common patterns of treatment failure. In patients with baseline brain metastasis, the intracranial ORR was 50%, and the DCR was 100%.

CONCLUSIONS

RET-TKI had favorable efficacy and safety in real-world contexts in China and should be considered the preferred choice for first-line treatment in RET-rearranged NSCLC patients.

Evolution of treatment strategies for solid tumors with RET rearrangement in China and real-world treatment status of Non-small Cell Lung Cancer (NSCLC)

OBJECTIVE

The present study endeavors to furnish an exhaustive review of the research advancements on solid tumors harboring RET rearrangement within the Chinese context, particularly emphasizing the examination of real-world therapeutic strategies and clinical outcomes observed in individuals diagnosed with advanced non-small cell lung cancer (NSCLC). The review delves into a critical assessment of the therapeutic efficacy of targeted RET inhibitors, while also scrutinizing the diverse array of treatment modalities employed in the Chinese patient population.

METHODS

The study conducted a comprehensive review of the advancements made by Chinese scholars in the realm of RET driver genes. It delved into the analysis of the incidence of RET rearrangements in solid tumors, alongside an examination of the varied treatment paradigms and their current status within China. Utilizing the RECIST 1.1 criteria, the study evaluated the therapeutic efficacy achieved in RET-positive NSCLC patients undergoing diverse treatment modalities. Furthermore, treatment-related adverse events (TRAEs) were meticulously graded following the Common Terminology Criteria for Adverse Events (CTCAE).

RESULTS

A retrospective, multi-center, real-world analysis was conducted, encompassing 64 patients diagnosed with pathologically confirmed RET rearrangement advanced non-small cell lung cancer (NSCLC) between December 2015 and November 2023. Notably, KIF5B-RET emerged as the most prevalent RET fusion partner, accounting for 59.4% of cases. Therapeutic interventions among these patients included specific targeted inhibitors such as Pralsetinib (48.4%), chemotherapy (34.3%), multi-target inhibitors (15.6%), and one case (1.6%) involving immunotherapy combined with anti-angiogenic therapy. In terms of progression-free survival (PFS), Pralsetinib monotherapy demonstrated a median PFS of 16.03 months, outperforming chemotherapy (2.87 months; p < 0.0001), chemotherapy combined with anti-angiogenic therapy (6.90 months; p = 0.048), and multi-target inhibitors (2.50 months; p < 0.0001). Furthermore, the one-year and two-year overall survival (OS) rates for Pralsetinib monotherapy were 64.3% and 46.4%, respectively. Regarding safety, 71.0% of patients receiving Pralsetinib experienced at least one adverse event, with 45.2% classified as grade 3-4 in severity. Notably, no fatalities were attributed to adverse events. Common adverse events included hemoglobin reduction (35.5%) and neutropenia (32.3%), indicative of an overall favorable safety profile for Pralsetinib in this patient population.

CONCLUSION

This study encapsulates the research endeavors and treatment advancements of RET rearrangement solid tumors within the Chinese healthcare landscape, specifically highlighting the diverse real-world therapeutic approaches and their effectiveness in managing advanced RET rearrangement NSCLC among Chinese patients. Notably, targeted RET inhibitors like Pralsetinib have emerged as potent therapeutic agents, exhibiting remarkable efficacy and a manageable safety profile in this patient cohort. These findings underscore the potential of Pralsetinib and similar targeted therapies as novel treatment options for individuals with RET fusion-positive NSCLC.

First-in-human, phase 1 dose-escalation and dose-expansion study of a RET inhibitor SY-5007 in patients with advanced RET-altered solid tumors

Oncogenic RET alteration is an important, tissue-agnostic therapeutic target across diverse cancers. We conducted a first-in-human phase 1 study on SY-5007, a potent and selective RET inhibitor, in patients with RET-altered solid tumors. Primary endpoints were safety, maximum tolerated dose (MTD), and recommended phase 2 dose (RP2D). Secondary endpoints included pharmacokinetics and preliminary anti-tumor activity. A total of 122 patients were enrolled (17 in dose-escalation phase and 105 in dose-expansion phase), including 91 with non-small cell lung cancer, 23 with medullary thyroid cancer, 7 with papillary thyroid cancer and 1 with gastric cancer. Treatment-related adverse events (TRAEs) were reported in 96.7% of patients, with the most common grade ≥ 3 TRAEs being hypertension (22.1%), diarrhea (16.4%), hypertriglyceridemia (6.6%), and neutropenia (6.6%). The exposure to SY-5007 was dose proportional. Among the 116 efficacy-evaluable patients, the overall objective response rate (ORR) was 57.8%, with 70.0% in treatment-naïve patients and 51.3% in previously treated patients. The median progression-free survival (PFS) was 21.1 months. Efficacy was observed regardless of tumor types and previous therapies. Biomarker analysis of 61 patients with circulating tumor DNA (ctDNA)-detectable RET alterations showed an ORR of 57.4% and median PFS of 13.8 months. Rapid ctDNA clearance of RET alteration correlated with faster responses and improved outcomes. In relapsed patients, off-target induced resistance was observed in 57.1% (12/21), with no on-target RET alterations identified. In conclusion, SY-5007 was well-tolerated and showed promising efficacy in patients with RET-altered solid tumors. Serial ctDNA monitoring may unveil treatment response and potential resistance mechanisms (NCT05278364).

Diagnosis, Treatment Patterns, and Outcomes in Real-World Patients with RET Fusion-Positive Non-small Cell Lung Cancer in China

INTRODUCTION

Epidemiological studies on non-small cell lung cancer (NSCLC) have noted RET fusions as an oncogenic driver. However, real-world data on RET biomarker testing and treatment patterns in China remain limited. This study aimed to examine demographics, clinical and molecular features, and RET testing and treatment patterns and outcomes in patients with RET fusion-positive NSCLC.

METHODS

Utilizing real-world data from the Chinese Multi-center Lung Cancer Precision Medicine Registry, this retrospective cohort study focused on Chinese patients diagnosed with RET fusion-positive NSCLC between January 1, 2016, and November 30, 2021. The cohort was divided into early-stage and advanced-stage subgroups. Demographics, clinical and molecular profiles, treatment received, and outcomes including real-world event free survival (rwEFS), real-world progression free survival (rwPFS), and overall survival (OS) were assessed.

RESULTS

The study included 121 patients with RET fusion-positive NSCLC, comprising 80 early-stage and 58 advanced-stage patients. High biomarker testing rates were observed at diagnosis (75% for early-stage, 78% for advanced-stage). RET testing was often conducted via tissue samples (95.9%) and next-generation sequencing (89.3%). KIF5B (57.0%) and CCDC6 (20.7%) were the most common gene fusion partners. The most frequent oncogenic mutations were TP53 (15.7%) and EGFR (6.6%). Platinum-based chemotherapy was the most common first-line treatment among advanced-stage patients. Median rwPFS was 9.22 months for advanced-stage patients on first-line chemotherapy, and median OS was 30.7 months for all advanced-stage patients. The 2-year rwEFS rate for early-stage patients was 86.0%, with a median OS of 91.9 months.

CONCLUSIONS

The study observed high biomarker testing rates at initial diagnosis for early- and advanced-stage RET fusion-positive NSCLC patients in China. The heterogeneous treatment pattern of advanced patients suggests the need for more precise, evidence-based treatment to guide clinical decisions. Given the existing therapeutic regimens fall short of adequately addressing treatment needs, targeted therapies are essential to improve outcomes.

Prognostic Indicators for Precision Treatment of Non-Small Cell Lung Carcinoma

Non-small cell lung cancer (NSCLC) has established predictive biomarkers that enable decisions on treatment regimens for many patients. However, resistance to therapy is widespread. It is therefore essential to have a panel of molecular biomarkers that may help overcome therapy resistance and prevent adverse effects of treatment. We performed in silico analysis of NSCLC prognostic indicators, separately for adenocarcinomas and squamous carcinomas, by using The Cancer Genome Atlas (TCGA) and non-TCGA data sources in cBioPortal as well as UALCAN. This review describes lung cancer biology, elaborating on the key genetic alterations and specific genes responsible for resistance to conventional treatments. Importantly, we examined the mechanisms associated with resistance to immune checkpoint inhibitors. Our analysis indicated that a robust prognostic biomarker was lacking for NSCLC, especially for squamous cell carcinomas. In this work, our screening uncovered previously unidentified prognostic gene expression indicators, namely, MYO1E, FAM83 homologs, and DKK1 for adenocarcinoma, and FGA and TRIB1 for squamous cell carcinoma. It was further observed that overexpression of these genes was associated with poor prognosis. Additionally, FAM83 homolog and TRIB1 unexpectedly harbored copy number amplifications. In conclusion, this study elucidated novel prognostic indicators for NSCLC that may serve as targets to overcome therapy resistance toward improved patient outcomes.

Efficacy and safety of pralsetinib in patients with RET fusion positive non-small cell lung cancer: An observational real world study

BACKGROUND

Pralsetinib, a selective RET targeted tyrosine kinase inhibitor (TKI), has been approved for treating locally advanced or metastatic RET fusion-positive NSCLC in adults who have previously received platinum-based chemotherapy in China.

METHODS

In this retrospective analysis conducted at Hunan Cancer Hospital in China, we examined 36 patients with advanced NSCLC with RET fusion, who were treated with pralsetinib between January 2021 and December 2023. The study focused on assessing the efficacy (Progression-free survival (PFS) and overall survival (OS)) and safety profile of pralsetinib in these patients. Statistical analyses were conducted using SPSS version 20.0, with a significance level set at p < 0.05.

RESULTS

The results revealed that pralsetinib exhibited significant activity in this patient cohort. Kaplan-Meier survival analysis indicated a median PFS of 10.7 months and a median OS of 21.2 months. The overall response rate(ORR) and disease control rate (DCR) was 55.6 % and 72.2 %, respectively. Pralsetinib was generally well tolerated, with most adverse events being mild to moderate (grades 1-2). The most common serious adverse events (≥grade 3) observed were lymphopenia (13.9 %), hypertension (11.1 %), leukopenia (8.3 %), neutropenia (8.3 %), and creatine kinase elevation (8.3 %).

CONCLUSION

Pralsetinib demonstrated promising activity in patients with advanced NSCLC harboring RET fusion with a favorable safety profile.

A case of neoadjuvant targeted therapy with pralsetinib for locally advanced lung adenocarcinoma with RET fusion mutation

This case report details the successful treatment of a 68-year-old male patient with locally advanced RET-rearranged lung adenocarcinoma using neoadjuvant pralsetinib. The patient initially presented with a suspicious right upper lobe nodule, which was later diagnosed as lung adenocarcinoma following genetic testing that revealed a RET exon 12 fusion. After 2 months of neoadjuvant treatment with pralsetinib, a significant radiological response was observed, with a reduction in tumor size and metabolic activity. Subsequently, the patient underwent video-assisted thoracoscopic right upper lobectomy and mediastinal lymph node dissection. Postoperative pathological analysis revealed a major pathological response, with only 5% residual tumor cells in the primary lesion and no viable tumor cells in the lymph nodes. Postoperative pathological staging of TNM was ypT1aN0M0, stage IA1(AJCC, 8th edition). The patient recovered well after surgery, demonstrating the potential efficacy of neoadjuvant pralsetinib in locally advanced RET-rearranged lung adenocarcinoma. However, further clinical validation is required to establish the role of neoadjuvant targeted therapy and postoperative adjuvant therapy in this patient population.

Adverse event profile differences between pralsetinib and selpercatinib: a real-world study based on the FDA adverse events reporting system

Aims

The objective of this study is to compare the adverse events (AEs) associated with pralsetinib and selpercatinib.

Methods

To evaluate the imbalance of AEs linked to pralsetinib and selpercatinib in real-world data, the reporting odds ratio (ROR) was utilized to detect potential signals of AEs. Stratified analysis was conducted to examine the differences in AEs occurring among different genders and age groups taking pralsetinib and selpercatinib.

Results

FAERS received 891 reports for pralsetinib and 569 reports for selpercatinib. Our analysis confirmed expected AEs like hypertension, fatigue, and elevated transaminase levels. Unexpected AEs such as rhabdomyolysis, myocardial injury and cognitive disorder were associated with pralsetinib, while selpercatinib was linked with pulmonary embolism, deep vein thrombosis, and pericardial effusion. The risk of AEs such as decreased platelet count, anemia, decreased white blood cell count, pneumonitis, asthenia, and edema caused by pralsetinib is significantly higher than that of selpercatinib. In contrast, the risk of AEs such as ascites, elevated alanine aminotransferase, and elevated aspartate aminotransferase caused by selpercatinib is significantly higher than that of pralsetinib. Women treated with pralsetinib experience higher rates of hypertension, pulmonary embolism, and blurred vision than men, who are more susceptible to rhabdomyolysis. Adults between 18 and 65 years are more likely to experience taste disorder, edema, and pulmonary embolism than individuals older than 65, who are particularly vulnerable to hypertension. For patients treated with selpercatinib, males demonstrate a significantly higher incidence of QT prolongation, urinary tract infection, and dysphagia. Individuals aged 18 to 65 are more likely to experience pyrexia and pleural effusion than those older than 65, who are more prone to hypersensitivity.

Conclusion

In the clinical administration of pralsetinib and selpercatinib, it is crucial to monitor the effects of gender and age on AEs and to be vigilant for unlisted AEs.

The evolving landscape of tissue-agnostic therapies in precision oncology

Tumor-agnostic therapies represent a paradigm shift in oncology by altering the traditional means of characterizing tumors based on their origin or location. Instead, they zero in on specific genetic anomalies responsible for fueling malignant growth. The watershed moment for tumor-agnostic therapies arrived in 2017, with the US Food and Drug Administration's historic approval of pembrolizumab, an immune checkpoint inhibitor. This milestone marked the marriage of genomics and immunology fields, as an immunotherapeutic agent gained approval based on genomic biomarkers, specifically, microsatellite instability-high or mismatch repair deficiency (dMMR). Subsequently, the approval of NTRK inhibitors, designed to combat NTRK gene fusions prevalent in various tumor types, including pediatric cancers and adult solid tumors, further underscored the potential of tumor-agnostic therapies. The US Food and Drug Administration approvals of targeted therapies (BRAF V600E, RET fusion), immunotherapies (tumor mutational burden ≥10 mutations per megabase, dMMR) and an antibody-drug conjugate (Her2-positive-immunohistochemistry 3+ expression) with pan-cancer efficacy have continued, offering newfound hope to patients grappling with advanced solid tumors that harbor particular biomarkers. In this comprehensive review, the authors delve into the expansive landscape of tissue-agnostic targets and drugs, shedding light on the rationale underpinning this approach, the hurdles it faces, presently approved therapies, voices from the patient advocacy perspective, and the tantalizing prospects on the horizon. This is a welcome advance in oncology that transcends the boundaries of histology and location to provide personalized options.

Cardiovascular toxicities of selective ret-specific tyrosine kinase inhibitors: a pharmacovigilance study based on the United States Food and Drug Administration Adverse Event Reporting System database

BACKGROUND

Selective RET-specific tyrosine kinase inhibitors (RET-TKIs) treat RET fusion-positive non-small cell lung cancer (NSCLC), but studies on their cardiovascular toxicities are limited. This study aimed to characterize the cardiovascular toxicities associated with selective RET-TKI in real-world settings.

RESEARCH DESIGN AND METHODS

Data from the United States Food and Drug Administration Adverse Event Reporting System database from 1 January 2020 to 30 June 2023, were analyzed. Two disproportionality methods, information component and reporting odds ratio (ROR) were used.

RESULTS

Both pralsetinib and selpercatinib showed positive signals for hypertension (pralsetinib: ROR: 5.25, 95% CI: 4.40-6.26; selpercatinib: ROR: 2.68, 95% CI: 1.87-3.82). Additionally, pralsetinib showed a positive signal for ischemic heart disease (ROR: 3.92, 95% CI: 2.94-5.23), and selpercatinib for torsade de pointes/QT prolongation (ROR: 2.65, 95% CI: 1.74-4.04). The median time to onset(TTO) of cardiovascular toxicities was 33 days (IQR: 9-73 days) for pralsetinib and 15 days (IQR: 10-50 days) for selpercatinib. The proportion of deaths, life-threatening events, and hospitalizations due to cardiovascular toxicities were 8.57%, 1.19%, and 31.43%, respectively, for total selective RET-TKI.

CONCLUSIONS

Selective RET-TKIs are related to multiple cardiovascular toxicities. Pralsetinib was linked to ischemic heart disease, and selpercatinib to torsade de pointes/QT prolongation and thrombotic events.

Non-Small-Cell Lung Cancers (NSCLCs) Harboring RET Gene Fusion, from Their Discovery to the Advent of New Selective Potent RET Inhibitors: "Shadows and Fogs"

RET fusions are relatively rare in Non-Small-Cell Lung Cancers (NSCLCs), being around 1-2% of all NSCLCs. They share the same clinical features as the other fusion-driven NSCLC patients, as follows: younger age, adenocarcinoma histology, low exposure to tobacco, and high risk of spreading to the brain. Chemotherapy and immunotherapy have a low impact on the prognosis of these patients. Multitargeted RET inhibitors have shown modest activity jeopardized by high toxicity. New potent and selective RET inhibitors (RET-Is) (pralsetinib and selpercatinib) have achieved a higher efficacy minimizing the known toxicities of the multitargeted agents. This review will describe the sensitivity of immune-checkpoint inhibitors (ICIs) in RET fusion + NSCLC patients, as well their experiences with the 'old' multi-targeted RET inhibitors. This review will focus on the advent of new potent and selective RET-Is. We will describe their efficacy as well as the main mechanisms of resistance to them. We will further proceed to deal with the new drugs and strategies proposed to overcome the resistance to RET-Is. In the last section, we will also focus on the safety profile of RET-Is, dealing with the main toxicities as well as the rare but severe adverse events.

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.

Novel therapeutic strategies for rare mutations in non-small cell lung cancer

Lung cancer is still the leading cause of cancer-related mortality. Over the past two decades, the management of non-small cell lung cancer (NSCLC) has undergone a significant revolution. Since the first identification of activating mutations in the epidermal growth factor receptor (EGFR) gene in 2004, several genetic aberrations, such as anaplastic lymphoma kinase rearrangements (ALK), neurotrophic tropomyosin receptor kinase (NTRK) and hepatocyte growth factor receptor (MET), have been found. With the development of gene sequencing technology, the development of targeted drugs for rare mutations, such as multikinase inhibitors, has provided new strategies for treating lung cancer patients with rare mutations. Patients who harbor this type of oncologic driver might acquire a greater survival benefit from the use of targeted therapy than from the use of chemotherapy and immunotherapy. To date, more new agents and regimens can achieve satisfactory results in patients with NSCLC. In this review, we focus on recent advances and highlight the new approval of molecular targeted therapy for NSCLC patients with rare oncologic drivers.

Improvement of assessment in surrogate endpoint and safety outcome of single-arm trials for anticancer drugs

INTRODUCTION

Single-arm trials (SATs) and surrogate endpoints were adopted as pivotal evidence for accelerated approval of anticancer drugs for more than 30 years. However, concerns regarding clinical evidence quality in trials, particularly in the SATs of anticancer drugs have increasingly been raised. SAT may not always provide strong evidence due to the lack of control and endpoint of overall survival that is typically present in randomized controlled trials.

AREAS COVERED

Clinical trial endpoint adjudication is a crucial factor in surrogate outcome measurement to ensure the data quality of the clinical trial of anticancer drugs. In this review, we systematically discuss the characteristics of adjudications in assessments in surrogate endpoint and safety outcome respectively, which are essential for ensuring reliable and transparent outcomes. Endpoint adjudication effectively reduces potential bias and mitigates variance that may be introduced by investigators when analyzing the medical records for the surrogate endpoints. We analyze the advantages and disadvantages of each type of adjudicator and provide a summary of the roles of adjudicators.

EXPERT OPINION

By suggestion of improving data reliability and transparency in pivotal trials, this review aims to supply a strategy for better clinical investigation for anticancer drugs, ultimately leading to better patient outcomes.

RET Fusion Testing in Patients With NSCLC: The RETING Study

Introduction

RET inhibitors with impressive overall response rates are now available for patients with NSCLC, yet the identification of RET fusions remains a difficult challenge. Most guidelines encourage the upfront use of next-generation sequencing (NGS), or alternatively, fluorescence in situ hybridization (FISH) or reverse transcriptase-polymerase chain reaction (RT-PCR) when NGS is not possible or available. Taken together, the suboptimal performance of single-analyte assays to detect RET fusions, although consistent with the notion of encouraging universal NGS, is currently widening some of the clinical practice gaps in the implementation of predictive biomarkers in patients with advanced NSCLC.

Methods

This situation prompted us to evaluate several RET assays in a large multicenter cohort of RET fusion-positive NSCLC (n = 38) to obtain real-world data. In addition to RNA-based NGS (the criterion standard method), all positive specimens underwent break-apart RET FISH with two different assays and were also tested by an RT-PCR assay.

Results

The most common RET partners were KIF5B (78.9%), followed by CCDC6 (15.8%). The two RET NGS-positive but FISH-negative samples contained a KIF5B(15)-RET(12) fusion. The three RET fusions not identified with RT-PCR were AKAP13(35)-RET(12), KIF5B(24)-RET(9) and KIF5B(24)-RET(11). All three false-negative RT-PCR cases were FISH-positive, exhibited a typical break-apart pattern, and contained a very high number of positive tumor cells with both FISH assays. Signet ring cells, psammoma bodies, and pleomorphic features were frequently observed (in 34.2%, 39.5%, and 39.5% of tumors, respectively).

Conclusions

In-depth knowledge of the advantages and disadvantages of the different RET testing methodologies could help clinical and molecular tumor boards implement and maintain sensible algorithms for the rapid and effective detection of RET fusions in patients with NSCLC. The likelihood of RET false-negative results with both FISH and RT-PCR reinforces the need for upfront NGS in patients with NSCLC.

Targeting RET alterations in non-small cell lung cancer

Rearranged during transfection (RET) alterations, which lead to aberrant activation of the RET proto-oncogene, have been identified in various cancers. In non-small cell lung cancer (NSCLC), RET mutations often manifest as RET fusion genes and are observed in 1-2 % of patients with NSCLC. In recent years, selective RET inhibitors such as selpercatinib and pralsetinib, approved by the Food and Drug Administration (FDA) in 2020, have been part of the revolutionary changes in the treatment landscape for non-small cell lung cancer. While first-generation RET inhibitors have become part of the standard of care for RET-fusion positive NSCLC, a new challenge has emerged: acquired resistance to RET inhibitors. RET resistance is a complex phenomenon that can manifest as either on-target or off-target resistance. Numerous studies have been conducted to identify the mechanisms behind this resistance. This review provides an overview of the biology of RET in NSCLC, methods of RET testing, and a comprehensive analysis of the clinical outcomes associated with multikinase and selective RET inhibitors for NSCLC. Additionally, we will explore future perspectives for RET fusion-positive NSCLC, including ongoing trials and the challenges involved in overcoming resistance to RET inhibitors.

Unraveling the Promise of RET Inhibitors in Precision Cancer Therapy by Targeting RET Mutations

Over the past decades, the role of rearranged during transfection (RET) alterations in tumorigenesis has been firmly established. RET kinase inhibition is an essential therapeutic target in patients with RET-altered cancers. In clinical practice, initial efficacy can be achieved in patients through the utilization of multikinase inhibitors (MKIs) with RET inhibitory activity. However, the effectiveness of these MKIs is impeded by the adverse events associated with off-target effects. Recently, many RET-selective inhibitors, characterized by heightened specificity and potency, have been developed, representing a substantial breakthrough in the field of RET precision oncology. This Perspective focuses on the contemporary understanding of RET mutations, recent advancements in next-generation RET inhibitors, and the challenges associated with resistance to RET inhibitors. It provides valuable insights for the development of next-generation MKIs and selective RET inhibitors.

Oncogenic alterations in advanced NSCLC: a molecular super-highway

Lung cancer ranks among the most common cancers world-wide and is the first cancer-related cause of death. The classification of lung cancer has evolved tremendously over the past two decades. Today, non-small cell lung cancer (NSCLC), particularly lung adenocarcinoma, comprises a multitude of molecular oncogenic subsets that change both the prognosis and management of disease.Since the first targeted oncogenic alteration identified in 2004, with the epidermal growth factor receptor (EGFR), there has been unprecedented progress in identifying and targeting new molecular alterations. Almost two decades of experience have allowed scientists to elucidate the biological function of oncogenic drivers and understand and often overcome the molecular basis of acquired resistance mechanisms. Today, targetable molecular alterations are identified in approximately 60% of lung adenocarcinoma patients in Western populations and 80% among Asian populations. Oncogenic drivers are largely enriched among non-smokers, east Asians, and younger patients, though each alteration has its own patient phenotype.The current landscape of druggable molecular targets includes EGFR, anaplastic lymphoma kinase (ALK), v-raf murine sarcoma viral oncogene homolog B (BRAF), ROS proto-oncogene 1 (ROS1), Kirstin rat sarcoma virus (KRAS), human epidermal receptor 2 (HER2), c-MET proto-oncogene (MET), neurotrophic receptor tyrosine kinase (NTRK), rearranged during transfection (RET), neuregulin 1 (NRG1). In addition to these known targets, others including Phosphoinositide 3-kinases (PI3K) and fibroblast growth factor receptor (FGFR) have garnered significant attention and are the subject of numerous ongoing trials.In this era of personalized, precision medicine, it is of paramount importance to identify known or potential oncogenic drivers in each patient. The development of targeted therapy is mirrored by diagnostic progress. Next generation sequencing offers high-throughput, speed and breadth to identify molecular alterations in entire genomes or targeted regions of DNA or RNA. It is the basis for the identification of the majority of current druggable alterations and offers a unique window into novel alterations, and de novo and acquired resistance mechanisms.In this review, we discuss the diagnostic approach in advanced NSCLC, focusing on current oncogenic driver alterations, through their pathophysiology, management, and future perspectives. We also explore the shortcomings and hurdles encountered in this rapidly evolving field.

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.

Pulmonary squamous cell carcinoma and lymphoepithelial carcinoma - morphology, molecular characteristics and differential diagnosis

Squamous cell carcinoma (SCC) comprises one of the major groups of non-small-cell carcinoma of the lung, and is subtyped into keratinising, non-keratinising and basaloid SCC. SCC can readily be diagnosed using histomorphology alone in keratinising SCC. Confirmatory immunohistochemical analyses should always be applied in non-keratinising and basaloid tumours to exclude differential diagnoses, most prominently adenocarcinoma and high-grade neuroendocrine carcinoma, which may have important therapeutic consequences. According to the World Health Organisation (WHO) classification 2015, the diagnosis of SCC can be rendered in resections of morphologically ambiguous tumours with squamous immunophenotype. In biopsies and cytology preparations in the same setting the current guidelines propose a diagnosis of 'non-small-cell carcinoma, favour SCC' in TTF1-negative and p40-positive tumours to acknowledge a possible sampling bias and restrict extended immunohistochemical evaluation in order to preserve tissue for molecular testing. Most SCC feature a molecular 'tobacco-smoke signature' with enrichment in GG > TT mutations, in line with the strong epidemiological association of SCC with smoking. Targetable mutations are extremely rare but they do occur, in particular in younger and non- or light-smoking patients, warranting molecular investigations. Lymphoepithelial carcinoma (LEC) is a poorly differentiated SCC with a syncytial growth pattern and a usually prominent lymphoplasmacytic infiltrate and frequent Epstein-Barr virus (EBV) association. In this review, we describe the morphological and molecular characteristics of SCC and LEC and discuss the most pertinent differential diagnoses.

Efficacy of first-line treatment options beyond RET-TKIs in advanced RET-rearranged non-small cell lung cancer: A multi-center real-world study

BACKGROUND

Although RET-tyrosine kinase inhibitors (RET-TKIs) are the preferred first-line therapy for advanced RET-arranged NSCLC, most patients cannot afford them. In this population, bevacizumab, immunotherapy, and chemotherapy are the most commonly used regimens. However, the optimal scheme beyond RET-TKIs has not been defined in the first-line setting.

METHODS

This retrospective study included 86 stage IV NSCLC patients harboring RET rearrangement from six cancer centers between May 2017 and October 2022. RET-TKIs, chemotherapy, or one of the combination therapies (including immune checkpoint inhibitor (ICI) combined with chemotherapy (I + C), bevacizumab combined with chemotherapy (B + C), ICI and bevacizumab combined with chemotherapy (I + B + C)), were used as the first-line therapeutics. The clinical outcomes and safety were evaluated.

RESULTS

Fourteen of the 86 patients received RET-TKIs, 57 received combination therapies, and 15 received chemotherapy alone. Their medium PFS (mPFS) were 16.92 months (95% CI: 5.9-27.9 months), 8.7 months (95% CI: 6.5-11.0 months), and 5.55 months (95% CI: 2.4-8.7 months) respectively. Among all the combination schemes, B + C (p = 0.007) or I + B + C (p = 0.025) gave beneficial PFS compared with chemotherapy, while I + C treatment (p = 0.169) generated comparable PFS with chemotherapy. In addition, I + B + C treatment had a numerically longer mPFS (12.21 months) compared with B + C (8.74 months) or I + C (7.89 months) schemes. In terms of safety, I + B + C treatment led to the highest frequency of hematological toxicity (50%) and vomiting (75%), but no ≥G3 adverse effect was observed.

CONCLUSIONS

I + B + C might be a preferred option beyond RET-TKIs in the first-line therapy of RET-arranged NSCLC. Combination with Bevacizumab rather than with ICIs offered favorable survival compared with chemotherapy alone.

Strategies for mitigating adverse events related to selective RET inhibitors in patients with RET-altered cancers

The US Food and Drug Administration (FDA) approval of the selective RET inhibitors selpercatinib and pralsetinib has led to a paradigm change in the treatment of RET-altered lung and thyroid cancers through a higher response rate and a more tolerable safety and toxicity profile than multi-kinase inhibitors. Recently, selpercatinib has received a tissue-agnostic FDA approval for all RET-fusion-positive cancers, and pralsetinib has shown pan-cancer activity as well. Given the anticipated increase in the use of both drugs across multiple tumor types, it is crucial to recognize the possible side effects and approaches for their optimal management in order to maximize the clinical benefit for treated patients. In this review, we underscore potential toxicities associated with selective RET inhibitors and discuss strategies to mitigate them.

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.

Prevalence of oncogenic driver mutations in Hispanics/Latin patients with lung cancer. A systematic review and meta-analysis

INTRODUCTION

The frequency of actionable mutations varies between races, and Hispanic/Latino (H/L) people are a population with different proportions of ancestry. Our purpose was to establish prevalence of actionable mutations in the H/L population with NSCLC.

METHODS

EMBASE, LILACS, MEDLINE, and Virtual Health Library were searched for studies published up to April 2023 that evaluated the prevalence of ALK, BRAF, EGFR, HER-2, KRAS, MET, NTRK, RET, ROS1 in H/L patients. Meta-analyses were done to determine prevalence using a random effects model.

RESULTS

Fifty-five articles were included. EGFR and KRAS were the most prevalent genes with high heterogeneity across the countries. The overall mutation frequency for EGFR was 22%. The most frequent mutations in the EGFR gene were del19 (10%) and L858R (7%). The mean of KRAS mutation was a 14% prevalence. KRASG12C was the most frequent mutation with a 7% prevalence in an entire population. The overall frequency of ALK rearrangement was 5%. The mean frequency of ROS-1 rearrangement was 2%, and the frequencies of HER-2, MET, BRAF, RET, NTRK molecular alterations were 4%, 3%, 2%, 2%, and 1% respectively. Almost half of the cases were male, and 65.8% had a history of tobacco exposure. The most common clinical stage was IV.

CONCLUSIONS

The prevalence of driver mutations such as EGFR and KRAS in LA populations differs from what is reported in Asians and Europeans. In the present article, countries with a high proportion of Amerindian ancestry show a greater prevalence of EGFR in contrast to countries with a high proportion of Caucasians. Lack of information on some countries or studies with a small sample size affects the real prevalence data for the region.

Efficacy and safety of pralsetinib in patients with advanced RET fusion-positive non-small cell lung cancer

BACKGROUND

Pralsetinib is a potent, selective RET inhibitor targeting oncogenic RET alterations. As part of the global, phase 1/2 ARROW trial (NCT03037385), the efficacy and safety of pralsetinib in Chinese patients with advanced RET fusion-positive non-small cell lung cancer (NSCLC) were evaluated.

METHODS

Adult patients with advanced, RET fusion-positive NSCLC with or without prior platinum-based chemotherapy were enrolled into two cohorts receiving 400-mg once-daily oral pralsetinib. Primary end points were objective response rates assessed by blinded independent central review and safety.

RESULTS

Of 68 patients enrolled, 37 had received prior platinum-based chemotherapy (48.6% with ≥3 prior systemic regimens) and 31 were treatment-naïve. As of March 4, 2022 (data cutoff), of the patients with measurable lesions at baseline, a confirmed objective response was observed in 22 (66.7%; 95% confidence interval [CI], 48.2-82.0) of 33 pretreated patients, including 1 (3.0%) complete response and 21 (63.6%) partial responses; and in 25 (83.3%; 95% CI, 65.3-94.4) of 30 treatment-naïve patients, including two (6.7%) complete responses and 23 (76.7%) partial responses. Median progression-free survival was 11.7 months (95% CI, 8.7-not estimable) in pretreated patients and 12.7 months (95% CI, 8.9-not estimable) in treatment-naïve patients. The most common grade 3/4 treatment-related adverse events in 68 patients were anemia (35.3%) and decreased neutrophil count (33.8%). Eight (11.8%) patients discontinued pralsetinib because of treatment-related adverse events.

CONCLUSION

Pralsetinib showed robust and durable clinical activity with a well-tolerated safety profile in Chinese patients with RET fusion-positive NSCLC.

CLINICAL TRIAL REGISTRATION

NCT03037385.

Understanding the feasibility of chemotherapeutic and immunotherapeutic targets against non-small cell lung cancers: an update of resistant responses and recent combinatorial therapies

Despite consistent progress in prompt diagnosis and curative therapies in the last decade, lung cancer (LC) continues to threaten mankind, accounting for nearly twice the casualties compared to prostate, breast, and other cancers. Statistics associate ~25% of 2021 cancer-related deaths with LC, more than 80% of which are explicitly caused by tobacco smoking. Prevailing as small and non-small cell pathologies, with respective occurring frequency of nearly 15% and 80-85%, non-small cell LCs (NSCLCs) are prominently distinguished into lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), subtypes. Since the first use of epidermal growth factor receptor (EGFR) inhibitor gefitinib for NSCLC treatment in 2002, immense progress has been made for targeted therapies with the next generation of drugs spanning across the chronological generations of small molecule inhibitors. The last two years have overseen the clinical approval of more than 10 therapeutic agents as first-line NSCLC medications. However, uncertain mutational aberrations as well as systemic resistant responses, and abysmal overall survival curtail the combating efficacies. Of late, immune checkpoint inhibitors (ICIs) against various molecules including programmed cell death-1 (PD-1) and its ligand (PD-L1) have been demonstrated as reliable LC treatment targets. Keeping these aspects in mind, this review article discusses the success of NSCLC chemo and immunotherapies with their characteristic effectiveness and future perspectives.

Targeting the RET tyrosine kinase in neuroblastoma: A review and application of a novel selective drug design strategy

The RET (REarranged during Transfection) gene, which encodes for a transmembrane receptor tyrosine kinase, is an established oncogene associated with the etiology and progression of multiple types of cancer. Oncogenic RET mutations and rearrangements resulting in gene fusions have been identified in many adult cancers, including medullary and papillary thyroid cancers, lung adenocarcinomas, colon and breast cancers, and many others. While genetic RET aberrations are much less common in pediatric solid tumors, increased RET expression has been shown to be associated with poor prognosis in children with solid tumors such as neuroblastoma, prompting an interest in RET inhibition as a form of therapy for these children. A number of kinase inhibitors currently in use for patients with cancer have RET inhibitory activity, but these inhibitors also display activity against other kinases, resulting in unwanted side effects and limiting their safety and efficacy. Recent efforts have been focused on developing more specific RET inhibitors, but due to high levels of conservation between kinase binding pockets, specificity remains a drug design challenge. Here, we review the background of RET as a potential therapeutic target in neuroblastoma tumors and the results of recent preclinical studies and clinical trials evaluating the safety and efficacy of RET inhibition in adults and children. We also present a novel approach to drug discovery leveraging the chemical phenomenon of atropisomerism to develop specific RET inhibitors and present preliminary data demonstrating the efficacy of a novel RET inhibitor against neuroblastoma tumor cells.

The efficacy and safety of selective RET inhibitors in RET fusion-positive non-small cell lung cancer: a meta-analysis

BACKGROUND

Rearranged during transfection (RET) fusion-positive occurs in approximately 2% of non-small cell lung cancer (NSCLC). This mutation often predicts metastasis risk and poor prognosis, and current mainstream therapies provide limited patient benefit. Selective RET inhibitors Pralsetinib and Selpercatinib are targeted drugs approved by the US Food and Drug Administration for treating RET-mutated tumors. The phase I/II clinical trial results of their treatment of NSCLC have been published. However, the clinical effect of selective RET inhibitors on RET fusion-positive NSCLC remains controversial. Purpose Meta-analysis was performed to investigate the efficacy and safety of selective RET inhibitors in treating RET fusion-positive NSCLC. Methods Qualified literature was searched in Pubmed, Cochrane Library, Embase, and Web of Science. Outcomes included objective response rate (ORR), median progression-free survival (mPFS), disease control rate (DCR), intracranial ORR, and adverse events. Stata 15.1 software was used to analyze the data. Results A total of 8 studies were included in this meta-analysis. The combined results showed that the ORR of patients treated with selective RET inhibitors was 67% (95% confidence interval:0.64 to 0.70, P < 0.01), DCR was 92% (95%CI: 0.91-0.94, P < 0.01), the mPFS was 16.09 months (95%CI: 11.66-20.52, P < 0.01). In treated patients with RET mutation, the intracranial ORR was 86% (95%CI:0.74 ~ 0.96, P < 0.01). ORR in untreated patients was more effective than untreated patients [HR = 0.44 (95%CI: 0.35-0.56, P < 0.01)]. The major adverse events (grade 3-4) are neutropenia (13%) and anaemia (13%). Conclusions Selective RET inhibitors Pralsetinib and Selpercatinib have shown a good effect on RET fusion-positive NSCLC, with a low incidence of adverse events.

Amplification of Wild-Type RET Represents a Novel Molecular Subtype of Several Cancer Types With Clinical Response to Selpercatinib

PURPOSE

RET rearrangements and RET activating point mutations represent targetable genomic alterations in advanced solid tumors. However, the frequency and clinicopathologic characteristics of wild-type RET amplification in cancer and its potential role as a targetable oncogenic driver are not well-characterized.

METHODS

In two institutional cohorts of patients with solid cancers from the Dana-Farber Cancer Institute (DFCI) and Memorial Sloan Kettering Cancer Center (MSKCC) whose tumors underwent next-generation sequencing (NGS), the frequency and clinicopathologic features of wild-type RET amplification in the absence of RET rearrangements or activating mutations was assessed. The findings were validated using merged data from The Cancer Genome Atlas (TCGA), Genomics Evidence Neoplasia Information Exchange (GENIE), and China Pan-Cancer data sets.

RESULTS

The frequency of wild-type RET amplification across all solid cancers was 0.08% (26 of 32,505) in the DFCI cohort, 0.05% (26 of 53,152) in the MSKCC cohort, and 0.25% (71 of 28,623) in the cohort from TCGA, GENIE, and China Pan-Cancer. Cancer types with RET amplification included non-small-cell lung cancer (NSCLC), hepatobiliary cancer, prostate cancer, breast cancer, and others. The median RET copy number in RET-amplified cases was 7.5 (range, 6-36) in the DFCI cohort and 5.7 (range, 4-27.7) in the MSKCC cohort. Among 11 RET-amplified NSCLCs, eight had no other concurrent driver mutations. Finally, we report on a 69-year-old man with recurrent NSCLC harboring high-level wild-type RET amplification (22-28 copies) as the only identified putative genomic driver who experienced both a systemic and intracranial confirmed response to the RET inhibitor selpercatinib.

CONCLUSION

Amplification of wild-type RET represents a novel, targetable molecular subset of cancer.

Targeted treatments after chemoradiotherapy failure in a patient with relapsed, advanced non‑small cell lung cancer with on‑therapy circulating tumor biomarker monitoring: A case report

Ongoing investigations of targeted therapeutic agents and their increased clinical applications, together with research in genomics and proteomics, have explored a variety of novel approaches for treatment of lung cancer, and 'molecular subtypes' have been defined based on specific actionable genetic aberrations. Liquid biopsies, including circulating tumor DNA (ctDNA) testing, are of value for cancer diagnosis and comprehensive genomic profiling, such as the identification of cancer subtypes and major genetic alterations in cancer cells. The case of a 66-year-old male patient with newly-diagnosed driver mutation-negative advanced non-small cell lung cancer (NSCLC) who underwent conventional therapy is described in the present report. The patient underwent regular monitoring, including continuous ctDNA analysis, imaging and assessment of tumor marker levels such as carcinoembryonic antigen (CEA). The patient initially presented with deep vein thrombosis which affected both lower extremities and without any symptoms in the lung, with a positron emission tomography scan identifying irregular pulmonary nodules in the right lower lobe and enlarged right supraclavicular lymph nodes. Subsequent ultrasound-guided fine-needle aspiration with nodule biopsy indicated advanced unresectable disease at stage IIIB based on the Tumor-Node-Metastasis staging system by the American Joint Committee on Cancer. Next-generation sequencing of tumor tissue and peripheral blood confirmed driver mutation-negative genes, including epidermal growth factor receptor, rat sarcoma, ALK receptor tyrosine kinase, ROS1 proto-oncogene receptor tyrosine kinase and rearrangement during transfection (RET). After 5 years of chemoradiotherapy and surveillance of ctDNA and CEA levels, detectable kinesin family member 5B (KIF5B)-RET fusion in ctDNA and rising CEA levels prompted early scans, which identified disease progression. The patient subsequently received the oral RET inhibitor pralsetinib, with treatment being currently ongoing for ≥17 months without detectable KIF5B-RET ctDNA or elevated CEA levels, with an ongoing minor response and stable disease based on Response Evaluation Criteria in Solid Tumors v1.1 on imaging. The present case illustrates the potential role of on-therapy circulating tumor biomarker monitoring as a non-traumatic method to evaluate therapy response and detect early disease progression in patients with advanced NSCLC. Integration of circulating tumor biomarker testing into the management of patients with advanced NSCLC requires additional prospective studies to actively assess and elucidate optimal treatment strategies.

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.

Challenges in the care of patients with RET-altered thyroid cancer: a multicountry mixed-methods study

BACKGROUND

The discovery of driver oncogenes for thyroid carcinomas and the identification of genomically targeted therapies to inhibit those oncogenes have altered the treatment algorithm in thyroid cancer (TC), while germline testing for RET mutations has become indicated for patients with a family history of RET gene mutations or hereditary medullary TC (MTC). In the context of an increasing number of selective RET inhibitors approved for use, this paper aims to describe challenges and barriers affecting providers' ability to deliver optimal care for patients with RET-altered TC across the patient healthcare journey.

METHODS

A mixed-method educational and behavioral needs assessment was conducted in Germany (GER), Japan (JPN), the United Kingdom (UK), and the United States (US) prior to RET-selective inhibitor approval. Participants included medical oncologists (MO), endocrinologists (EN) and clinical pathologists (CP) caring for patients affected with TC. Data collection tools were implemented in three languages (English, German, Japanese). Qualitative data were coded and thematically analyzed in NVivo. Quantitative data were analyzed via frequency and crosstabulations in SPSS. The findings presented here were part of a broader study that also investigated lung cancer challenges and included pulmonologists.

RESULTS

A total of 44 interviews and 378 surveys were completed. Suboptimal knowledge and skills were self-identified among providers, affecting (1) assessment of genetic risk factors (56%, 159/285 of MOs and ENs), (2) selection of appropriate genetic biomarkers (59%, 53/90 of CPs), (3) treatment plan initiation (65%, 173/275 of MOs and ENs), (4) management of side effects associated with multitargeted tyrosine kinase inhibitors (78%, 116/149 of MOs and ENs), and (5) transfer of patients into palliative care services (58%, 160/274 of MOs and ENs). Interviews underscored the presence of systemic barriers affecting the use of RET molecular tests and selective inhibitors, in addition to suboptimal knowledge and skills necessary to manage the safety and efficacy of targeted therapies.

CONCLUSION

This study describes concrete educational needs for providers involved in the care of patients with RET-altered thyroid carcinomas. Findings can be used to inform the design of evidence-based education and performance improvement interventions in the field and support integration into practice of newly approved RET-selective inhibitors.

Recent advances in non-small cell lung cancer targeted therapy; an update review

Lung cancer continues to be the leading cause of cancer-related death worldwide. In the last decade, significant advancements in the diagnosis and treatment of lung cancer, particularly NSCLC, have been achieved with the help of molecular translational research. Among the hopeful breakthroughs in therapeutic approaches, advances in targeted therapy have brought the most successful outcomes in NSCLC treatment. In targeted therapy, antagonists target the specific genes, proteins, or the microenvironment of tumors supporting cancer growth and survival. Indeed, cancer can be managed by blocking the target genes related to tumor cell progression without causing noticeable damage to normal cells. Currently, efforts have been focused on improving the targeted therapy aspects regarding the encouraging outcomes in cancer treatment and the quality of life of patients. Treatment with targeted therapy for NSCLC is changing rapidly due to the pace of scientific research. Accordingly, this updated study aimed to discuss the tumor target antigens comprehensively and targeted therapy-related agents in NSCLC. The current study also summarized the available clinical trial studies for NSCLC patients.

Usefulness of an RNA extraction-free test for the multiplexed detection of ALK, ROS1, and RET Gene Fusions in Real Life FFPE Specimens of Non-Small Cell Lung Cancers

BACKGROUND

ALK, ROS1 and RET rearrangements occur, respectively, in 5%, 2%, and 1% non-small cell lung cancers (NSCLC). ALK and ROS1 fusion proteins detection by immunohistochemistry (IHC) has been validated for rapid patient screening, but ROS1 fusions need to be confirmed by another technique and no RET IHC test is available for clinical use.

RESEARCH DESIGN AND METHODS

We report herein the usefulness of the HTG EdgeSeq Assay, an RNA extraction-free test combining a quantitative nuclease protection assay with NGS, for the detection of ALK, ROS1 and RET fusions from 'real-life' small NSCLC samples. A total of 203 FFPE samples were collected from 11 centers. They included 143 rearranged NSCLC (87 ALK, 39 ROS1, 17 RET) and 60 ALK-ROS1-RET negative controls.

RESULTS

The assay had a specificity of 98% and a sensitivity for ALK, ROS1 and RET fusions of 80%, 94% and 100% respectively. Among the 19 HTG-assay false negative samples, the preanalytical conditions were identified as the major factors impacting the assay efficiency.

CONCLUSIONS

Overall, the HTG EdgeSeq assay offers comparable sensitivities and specificity than other RNA sequencing techniques, with the advantage that it can be used on very small and old samples collected multicentrically.

Rapid and Cost-Efficient Detection of RET Rearrangements in a Large Consecutive Series of Lung Carcinomas

RET-kinase-activating gene rearrangements occur in approximately 1-2% of non-small-cell lung carcinomas (NSCLCs). Their reliable detection requires next-generation sequencing (NGS), while conventional methods, such as immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) or variant-specific PCR, have significant limitations. We developed an assay that compares the level of RNA transcripts corresponding to 5'- and 3'-end portions of the RET gene; this test relies on the fact that RET translocations result in the upregulation of the kinase domain of the gene and, therefore, the 5'/3'-end expression imbalance. The present study included 16,106 consecutive NSCLC patients, 14,449 (89.7%) of whom passed cDNA quality control. The 5'/3'-end unbalanced RET expression was observed in 184 (1.3%) tumors, 169 of which had a sufficient amount of material for the identification of translocation variants. Variant-specific PCR revealed RET rearrangements in 155/169 (91.7%) tumors. RNA quality was sufficient for RNA-based NGS in 10 cases, 8 of which carried exceptionally rare or novel (HOOK1::RET and ZC3H7A::RET) RET translocations. We also applied variant-specific PCR for eight common RET rearrangements in 4680 tumors, which emerged negative upon the 5'/3'-end unbalanced expression test; 33 (0.7%) of these NSCLCs showed RET fusion. While the combination of the analysis of 5'/3'-end RET expression imbalance and variant-specific PCR allowed identification of RET translocations in approximately 2% of consecutive NSCLCs, this estimate approached 120/2361 (5.1%) in EGFR/KRAS/ALK/ROS1/BRAF/MET-negative carcinomas. RET-rearranged tumors obtained from females, but not males, had a decreased level of expression of thymidylate synthase (p < 0.00001), which is a known predictive marker of the efficacy of pemetrexed. The results of our study provide a viable alternative for RET testing in facilities that do not have access to NGS due to cost or technical limitations.

Precision oncology with selective RET inhibitor selpercatinib in RET-rearranged cancers

Rearranged during transfection (RET) is a protooncogene that encodes for receptor tyrosine kinase with downstream effects on multiple cellular pathways. Activating RET alterations can occur and lead to uncontrolled cellular proliferation as a hallmark of cancer development. Oncogenic RET fusions are present in nearly 2% of patients with non-small cell lung cancer (NSCLC), 10-20% of patients with thyroid cancer, and <1% across the pan-cancer spectrum. In addition, RET mutations are drivers in 60% of sporadic medullary thyroid cancers and 99% of hereditary thyroid cancers. The discovery, rapid clinical translation, and trials leading to FDA approvals of selective RET inhibitors, selpercatinib and pralsetinib, have revolutionized the field of RET precision therapy. In this article, we review the current status on the use of the selective RET inhibitor, selpercatinib, in RET fusion-positive tumors: NSCLC, thyroid cancers, and the more recent tissue-agnostic activity leading to FDA approval.