Precision oncology for RET-related tumors

Low-density lipoprotein receptor-related protein 5/6 promotes endometrial cancer progression and cancer cell immune escape

The study investigated the potential association of the low-density lipoprotein (LDL) genome with endometrial cancer progression based on the Gene Expression Omnibus data set and The Cancer Genome Atlas data set. Differential and weighted gene coexpression network analysis was performed on endometrial cancer transcriptome datasets GSE9750 and GSE106191. The protein-protein interaction network was built using LDL-receptor proteins and the top 50 tumor-associated genes. Low-density lipoprotein-related receptors 5/6 (LRP5/6) in endometrial cancer tissues were correlated with oncogenes, cell cycle-related genes, and immunological checkpoints using Spearman correlation. MethPrimer predicted the LRP5/6 promoter CpG island. LRP2, LRP6, LRP8, LRP12, low-density lipoprotein receptor-related protein-associated protein, and LRP5 were major LDL-receptor-related genes associated with endometrial cancer. LRP5/6 was enriched in various cancer-related pathways and may be a key LDL-receptor-related gene in cancer progression. LRP5/6 may be involved in the proliferation process of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may be involved in the proliferation of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may promote the immune escape of cancer cells by promoting the expression of immune checkpoints, promoting endometrial cancer progression. The MethPrimer database predicted that the LRP5/6 promoter region contained many CpG islands, suggesting that DNA methylation can occur in the LRP5/6 promoter region. LRP5/6 may aggravate endometrial cancer by activating the phosphoinositide 3-kinase/protein kinase B pathway.

RET splice site variants in medullary thyroid carcinoma

Introduction: Medullary thyroid carcinoma (MTC) is an aggressive cancer that is often caused by driver mutations in RET. Splice site variants (SSV) reflect changes in mRNA processing, which may alter protein function. RET SSVs have been described in thyroid tumors in general but have not been extensively studied in MTC. Methods: The prevalence of RET SSVs was evaluated in 3,624 cases with next generation sequence reports, including 25 MTCs. Fisher exact analysis was performed to compare RET SSV frequency in cancers with/without a diagnosis of MTC. Results: All 25 MTCs had at least one of the two most common RET SSVs versus 0.3% of 3,599 cancers with other diagnoses (p < 0.00001). The 11 cancers with non-MTC diagnoses that had the common RET SSVs were 4 neuroendocrine cancers, 4 non-small cell lung carcinomas, 2 non-MTC thyroid cancers, and 1 melanoma. All 25 MTCs analyzed had at least one of the two most common RET SSVs, including 4 with no identified mutational driver. Discussion: The identification of RET SSVs in all MTCs, but rarely in other cancer types, demonstrates that these RET SSVs distinguish MTCs from other cancer types. Future studies are needed to investigate whether these RET SSVs play a pathogenic role in MTC.

The Pathogenic RET Val804Met Variant in Acromegaly: A New Clinical Phenotype?

Several genetic investigations were conducted to identify germline and somatic mutations in somatotropinomas, a subtype of pituitary tumors. To our knowledge, we report the first acromegaly patient carrying a RET pathogenic variant: c.2410G>A (rs79658334), p.Val804Met. Alongside the fact that the patient's father and daughter carried the same variant, we investigated the clinical significance of this variant in the context of somatotropinomas and other endocrine tumors, reviewing the RET mutations' oncogenic mechanisms. The aim was to search for new targets to precisely manage and treat acromegaly. Our case describes a new phenotype associated with the RET pathogenic variant, represented by aggressive acromegaly, and suggests consideration for RET mutation screening if NGS for well-established PitNET-associated gene mutations renders negative.

Characteristics and Survival Outcomes of Patients With Metastatic RET Fusion-Positive Solid Tumors Receiving Non-RET Inhibitor Standards of Care in a Real-World Setting

PURPOSE

RET fusions are oncogenic drivers across different solid tumors. However, the genomic landscape and natural history of patients with RET fusion-positive solid tumors are not well known. We describe the clinical characteristics of RET tyrosine kinase inhibitor (TKI)-naïve patients with RET fusion-positive solid tumors (excluding non-small-cell lung cancer [NSCLC]), treated in a real-world setting and assess the prognostic effect of RET fusions.

METHODS

Data for RET TKI-naïve patients with metastatic solid tumors (excluding NSCLC) who had ≥one Foundation Medicine comprehensive genomic profiling test (January 1, 2011-March 31, 2022) were obtained from a deidentified nationwide (US-based) clinicogenomic database. The primary objective of this study was to compare the overall survival (OS) of patients with RET fusion-positive tumors versus matched patients with RET wild-type (RET-WT) tumors. Patients with RET-WT solid tumors were matched (4:1) to patients with RET fusion-positive tumors on the basis of preselected covariates.

RESULTS

The study population included 26 patients in the RET fusion-positive cohort, 7,220 patients in the RET-WT cohort (before matching), and 104 patients in the matched RET-WT cohort. Co-occurring genomic alterations were rare in the RET fusion-positive cohort. Median OS was consistently lower in patients with RET fusion-positive tumors versus those with RET-WT tumors, using three different analyses (hazard ratios, 2.0, 1.7, and 2.2).

CONCLUSION

These data suggest that RET fusions represent a negative prognostic factor in patients with metastatic solid tumors and highlight the need for wider genomic testing and use of RET-specific TKIs that could improve patient outcomes. Our study also highlights the value of real-world data when studying rare cancers or cancers with rare genomic alterations.

A Clinical Viewpoint on the Use of Targeted Therapy in Advanced Gastric Cancer

The development of therapies for advanced gastric cancer (GC) has made significant progress over the past few years. The identification of new molecules and molecular targets is expanding our understanding of the disease's intricate nature. The end of the classical oncology era, which relied on well-studied chemotherapeutic agents, is giving rise to novel and unexplored challenges, which will cause a significant transformation of the current oncological knowledge in the next few years. The integration of established clinically effective regimens in additional studies will be crucial in managing these innovative aspects of GC. This study aims to present an in-depth and comprehensive review of the clinical advancements in targeted therapy and immunotherapy for advanced GC.

A unified DNA- and RNA-based NGS strategy for the analysis of multiple types of variants at the dual nucleic acid level in solid tumors

BACKGROUND

Targeted next-generation sequencing (NGS) is a powerful and suitable approach to comprehensively identify multiple types of variants in tumors. RNA-based NGS is increasingly playing an important role in precision oncology. Both parallel and sequential DNA- and RNA-based approaches are expensive, burdensome, and have long turnaround times, which can be impractical in clinical practice. A streamlined, unified DNA- and RNA-based NGS approach is urgently needed in clinical practice.

METHODS

A DNA/RNA co-hybrid capture sequencing (DRCC-Seq) approach was designed to capture pre-capture DNA and RNA libraries in a single tube and convert them into one NGS library. The performance of the DRCC-Seq approach was evaluated by a panel of reference standards and clinical samples.

RESULTS

The average depth, DNA data ratio, capture ratio, and target coverage 250 (×) of the DNA panel data had a negative correlation with an increase in the proportion of RNA probes. The SNVs, indels, fusions, and MSI status were not affected by the proportion of RNA probes, but the copy numbers of the target genes were higher than expected in the standard materials, and many unexpected gene amplifications were found using D:R (1:2) and D:R (1:4) probe panels. The optimal ratio of DNA and RNA probes in the combined probe panel was 1:1 using the DRCC-Seq approach. The DRCC-Seq approach was feasible and reliable for detecting multiple types of variants in reference standards and real-world clinical samples.

CONCLUSIONS

The DRCC-Seq approach is more cost-effective, with a shorter turnaround time and lower labor requirements than either parallel or sequential targeted DNA NGS and RNA NGS. It is feasible to identify multiple genetic variations at the DNA and RNA levels simultaneously in clinical practice.

Clinical Characteristics and Responses to Immune Checkpoint Inhibitors in RET-Aberrant Digestive Tract Tumours

BACKGROUND

RET plays an oncogenic role, and its aberrations are potentially actionable. However, they have seldom been reported in tumours other than lung or thyroid cancers. The correlation of RET aberrations with clinical characteristics, co-occurring aberrations, and responses to immune checkpoint inhibitors (ICPi) have not been explored in digestive tract tumours.

OBJECTIVES

The aim of the study was to elucidate the clinical characteristics, frequently co-altered genes, and treatment responses in RET-aberrant digestive tract tumours.

PATIENTS AND METHODS

We retrospectively evaluated patients with digestive tract cancers for RET-aberrant tumours via FoundationOne CDx tumour-based selected genome sequencing from Jan 2016 to Jan 2021.

RESULTS

In a median follow-up time of 51 months, a total of 453 patients were analysed. RET-aberrant tumours accounted for 4.4% in the studied population (n = 20), and 1.1% had an oncogenic fusion (n = 5). APC, KRAS, TP53, MSH6 and STK11 were the differentially co-altered genes (all false discovery rates <0.05). The presence of RET aberrations alone was not a significant prognostic factor. Eleven patients with RET-aberrant tumours received ICPi-based treatment and none achieved an objective response. In contrast, 47 patients with non-aberrant tumours received ICPi treatment and had an objective response rate of 27.7% and a significantly longer treatment duration (6.2 vs 2.8 months, p = 0.0008).

CONCLUSIONS

Albeit rarely, RET aberrations can be found in digestive tract tumours. Patients with RET-aberrant tumours have a blunted response to ICPi and a comparable prognosis as compared with RET-wild type tumours. Together, these results provide insights into this rare but potentially actionable target in digestive tract tumours.

Molecular mechanisms of the tyrosine kinase inhibitor pralsetinib activity in in-vitro models of medullary thyroid carcinoma: Aberrant activation of the HH-Gli signaling pathway in acquired resistance

Medullary thyroid carcinoma (MTC) is a malignant tumor with challenging management. Multi-targeted kinase inhibitors (MKI) and tyrosine-kinase inhibitors (TKI) with high specificity for RET protein are approved for advanced MTC treatment. However, their efficacy is hindered by evasion mechanisms of tumor cells. Thus, the aim of this study was the identification of an escape mechanism in MTC cells exposed to a highly selective RET TKI. TT cells were treated with TKI, MKI, and/or the HH-Gli inhibitors, GANT61 and Arsenic Trioxide (ATO), in the presence or absence of hypoxia. RET modifications, oncogenic signaling activation, proliferation and apoptosis were assessed. Additionally, cell modifications and HH-Gli activation were also evaluated in pralsetinib-resistant TT cells. Pralsetinib inhibited RET autophosphorylation and RET downstream pathways activation in normoxic and hypoxic conditions. Additionally, pralsetinib impaired proliferation, induced the activation of apoptosis and, in hypoxic cells, downregulated HIF-1α. Focusing on escape molecular mechanisms associated with therapy, we observed increased Gli1 levels in a subset of cells. Indeed, pralsetinib stimulated the re-localization of Gli1 into the cell nuclei. Treatment of TT cells with both pralsetinib and ATO resulted in Gli1 down-regulation and impaired cell viability. Moreover, pralsetinib-resistant cells confirmed Gli1 activation and up-regulation of its transcriptionally regulated target genes. Altogether, we showed that pralsetinib impairs MTC cell growth and induces cell death, also in hypoxic conditions. The HH-Gli pathway is a new molecular mechanism of escape to pralsetinib therapy that can be overcome through combined therapy.

Metabolic adverse events of multitarget kinase inhibitors: a systematic review

PURPOSE

Multitargeted kinase inhibitors (MKIs) are used for the treatment of several cancers. By targeting multiple signaling pathways, MKIs have become cornerstones of the oncologic treatment. Although their use leads to important results in terms of survival, treatment with MKIs can determine important side effects the clinician must be aware of. Among those, arterial hypertension, mucositis and skin lesions are universally reported, while data about metabolic alterations are scarce. In our review, we focused on glucose and lipid alterations in MKI-treated patients.

METHODS

We searched for articles, published between January 2012 and December 2022, evaluating the effects on lipid and glucose metabolism of four MKIs (Cabozantinib, Lenvatinib, Sorafenib, and Vandetanib) in adult patients with cancer. We focused on drugs approved for thyroid malignancies, since a worse metabolic control may potentially impact life expectancy, due to their better overall survival rate.

RESULTS

As for glucose metabolism, the majority of the studies reported elevation of glucose levels (prevalence: 1-17%) with different grades of severity, including death. As for cholesterol, 12 studies reported worsening or new-onset hypercholesterolemia (prevalence: 4-40%). Finally, 19 studies reported different grades of hypertriglyceridemia (prevalence: 1-86%), sometimes leading to life-threatening events.

CONCLUSIONS

Despite some inherent limitations, our analysis may cast light upon some of the MKIs metabolic disorders that can impact on patients' health, especially when long-term survival is expected. Future clinical trials should consider routine assessment of glucose and lipid levels, because underdetection and underreporting of alterations can lead to the overlooking of important adverse events.

Personalized Systemic Therapies in Hereditary Cancer Syndromes

Hereditary cancer syndromes are inherited disorders caused by germline pathogenic variants (PVs) that lead to an increased risk of developing certain types of cancer, frequently at an earlier age than in the rest of the population. The germline PVs promote cancer development, growth and survival, and may represent an ideal target for the personalized treatment of hereditary tumors. PARP inhibitors for the treatment of BRCA and PALB2-associated tumors, immune checkpoint inhibitors for tumors associated with the Lynch Syndrome, HIF-2α inhibitor in the VHL-related cancers and, finally, selective RET inhibitors for the treatment of MEN2-associated medullary thyroid cancer are the most successful examples of how a germline PVs can be exploited to develop effective personalized therapies and improve the outcome of these patients. The present review aims to describe and discuss the personalized systemic therapies for inherited cancer syndromes that have been developed and investigated in clinical trials in recent decades.

A comprehensive overview of the relationship between RET gene and tumor occurrence

RET gene plays significant roles in the nervous system and many other tissues. Rearranged during transfection (RET) mutation is related to cell proliferation, invasion, and migration. Many invasive tumors (e.g., non-small cell lung cancer, thyroid cancer, and breast cancer) were found to have changes in RET. Recently, great efforts have been made against RET. Selpercatinib and pralsetinib, with encouraging efficacy, intracranial activity, and tolerability, were approved by the Food and Drug Administration (FDA) in 2020. The development of acquired resistance is inevitable, and a deeper exploration should be conducted. This article systematically reviewed RET gene and its biology as well as the oncogenic role in multiple cancers. Moreover, we also summarized recent advances in the treatment of RET and the mechanism of drug resistance.

Targeted therapy of RET fusion-positive non-small cell lung cancer

Lung cancer has very high morbidity and mortality worldwide, and the prognosis is not optimistic. Previous treatments for non-small cell lung cancer (NSCLC) have limited efficacy, and targeted drugs for some gene mutations have been used in NSCLC with considerable efficacy. The RET proto-oncogene is located on the long arm of chromosome 10 with a length of 60,000 bp, and the expression of RET gene affects cell survival, proliferation, growth and differentiation. This review will describe the basic characteristics and common fusion methods of RET genes; analyze the advantages and disadvantages of different RET fusion detection methods; summarize and discuss the recent application of non-selective and selective RET fusion-positive inhibitors, such as Vandetanib, Selpercatinib, Pralsetinib and Alectinib; discuss the mechanism and coping strategies of resistance to RET fusion-positive inhibitors.