Rearranged During Transfection Fusions in Non-Small Cell Lung Cancer

Real-World Outcomes of Selective RET Inhibitor Selpercatinib in the United States: Descriptive, Retrospective Findings from Two Databases

OBJECTIVES

This study described real-world patient characteristics and outcomes among selpercatinib-treated patients in the United States, using the Flatiron Health electronic health record-derived deidentified database (FHD) for advanced/metastatic non-small cell lung cancer (a/mNSCLC) and Optum's de-identified Clinformatics® Data Mart Database (CDM).

METHODS

Patients initiating selpercatinib treatment between 08MAY2020 and 30JUN2023 were included. We evaluated real-world time to selpercatinib treatment discontinuation or death (rwTTDd) and time to next treatment or death (rwTTNTd) using Kaplan-Meier analyses. Medication possession ratio (MPR) was estimated as a measure of medication adherence in CDM patients.

RESULTS

In a/mNSCLC patients from the FHD (N = 68), the median rwTTDd and rwTTNTd were 22.4 [95%CI: 13.3-NR] and 21.0 [95%CI: 11.6-NR] months, respectively. In CDM, these durations were 12.1 [95%CI: 9.6-NR] and 16.2 [95%CI: 9.6-NR] months for lung cancer (n = 43), while these were not reached for thyroid cancer (n = 24) patients. The median MPR was 0.98 [IQR: 0.84-1.00] among all patients in the CDM (N = 75), with 77.3% of patients adhering (MPR ≥ 0.80) to selpercatinib.

CONCLUSIONS

Real-world outcomes in this older and frailer patient cohort align with phase 3 trial results, further supporting selpercatinib as the standard of care for patients with RET-altered cancers. Early testing for the detection of RET alterations remains essential.

Cheminformatics-based identification of phosphorylated RET tyrosine kinase inhibitors for human cancer

Background

Rearranged during transfection (RET), an oncogenic protein, is associated with various cancers, including non-small-cell lung cancer (NSCLC), papillary thyroid cancer (PTC), pancreatic cancer, medullary thyroid cancer (MTC), breast cancer, and colorectal cancer. Dysregulation of RET contributes to cancer development, highlighting the importance of identifying lead compounds targeting this protein due to its pivotal role in cancer progression. Therefore, this study aims to discover effective lead compounds targeting RET across different cancer types and evaluate their potential to inhibit cancer progression.

Methods

This study used a range of computational techniques, including Phase database creation, high-throughput virtual screening (HTVS), molecular docking, molecular mechanics with generalized Born surface area (MM-GBSA) solvation, assessment of pharmacokinetic (PK) properties, and molecular dynamics (MD) simulations, to identify potential lead compounds targeting RET.

Results

Initially, a high-throughput virtual screening of the ZINC database identified 2,550 compounds from a pool of 170,269. Subsequent molecular docking studies revealed 10 compounds with promising negative binding scores ranging from -8.458 to -7.791 kcal/mol. MM-GBSA analysis further confirmed the potential of four compounds to exhibit negative binding scores. MD simulations demonstrated the stability of CID 95842900, CID 137030374, CID 124958150, and CID 110126793 with the target receptors.

Conclusion

These findings suggest that these selected four compounds have the potential to inhibit phosphorylated RET (pRET) tyrosine kinase activity and may represent promising candidates for the treatment of various cancers.

The importance of protein domain mutations in cancer therapy

Cancer is a complex disease that is caused by multiple genetic factors. Researchers have been studying protein domain mutations to understand how they affect the progression and treatment of cancer. These mutations can significantly impact the development and spread of cancer by changing the protein structure, function, and signalling pathways. As a result, there is a growing interest in how these mutations can be used as prognostic indicators for cancer prognosis. Recent studies have shown that protein domain mutations can provide valuable information about the severity of the disease and the patient's response to treatment. They may also be used to predict the response and resistance to targeted therapy in cancer treatment. The clinical implications of protein domain mutations in cancer are significant, and they are regarded as essential biomarkers in oncology. However, additional techniques and approaches are required to characterize changes in protein domains and predict their functional effects. Machine learning and other computational tools offer promising solutions to this challenge, enabling the prediction of the impact of mutations on protein structure and function. Such predictions can aid in the clinical interpretation of genetic information. Furthermore, the development of genome editing tools like CRISPR/Cas9 has made it possible to validate the functional significance of mutants more efficiently and accurately. In conclusion, protein domain mutations hold great promise as prognostic and predictive biomarkers in cancer. Overall, considerable research is still needed to better define genetic and molecular heterogeneity and to resolve the challenges that remain, so that their full potential can be realized.

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

Background

Patient-reported outcomes (PROs) are increasingly becoming an important part of clinical trials as they are helpful in analyzing the safety and efficacy of treatment in chronic diseases like cancer.

Objectives

We report PROs and health-related quality of life (HRQoL) with selpercatinib treatment among Chinese patients with rearranged in transfection (RET) fusion-positive non-small-cell lung cancer (NSCLC), RET fusion-positive thyroid cancer (TC), and RET-mutant medullary TC (MTC) as an exploratory analysis of the LIBRETTO-321 trial.

Design

A total of 77 patients (47 RET fusion-positive NSCLC, 1 RET fusion-positive TC, and 29 RET-mutant MTC) were enrolled. Compliance for European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core 30 (QLQ-C30) was 100% at baseline and >90% at each time point.

Methods

PROs were assessed using the EORTC QLQ-C30, and a bowel diary assessment for MTC patients with baseline diarrhea using the Systemic Therapy-Induced Diarrhea Assessment Tool. Data were collected at pre-dose; every 8 weeks from cycle 3; and every 12 weeks after cycle 13. A >10-point change from baseline was considered clinically meaningful. PRO changes were summarized through cycle 13.

Results

Most patients with NSCLC or MTC showed improvement or remained stable on the global health status and functional subscales. For global health status, 47.4% of NSCLC and MTC patients showed definite improvement with only 19.7% showing definite worsening. For functional subscales, less than 30% of the patients showed definite worsening. For symptom subscales, more than 64% of the patients either improved or remained stable for the symptoms. For MTC patients with bowel diary assessment (n = 5), there was no severity or worsening from baseline in the diarrheal episodes observed during treatment with selpercatinib.

Conclusion

The study demonstrated favorable PROs in Chinese patients with RET fusion-positive NSCLC, TC, and RET-mutant MTC treated with selpercatinib. HRQoL was improved or stable as assessed by EORTC QLQ-30.

Trail registration

This study was registered at ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT04280081) ClinicalTrials.gov Identifier: NCT04280081.

Precious Gene: The Application of RET-Altered Inhibitors

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

Antitarget Selectivity and Tolerability of Novel Pyrrolo[2,3-d]pyrimidine RET Inhibitors

The selective inhibition of RET kinase as a treatment for relevant cancer types including lung adenocarcinoma has garnered considerable interest in recent years and prompted a variety of efforts toward the discovery of small-molecule therapeutics. Hits uncovered via the analysis of archival kinase data ultimately led to the identification of a promising pyrrolo[2,3-d]pyrimidine scaffold. The optimization of this pyrrolo[2,3-d]pyrimidine core resulted in compound 1, which demonstrated potent in vitro RET kinase inhibition and robust in vivo efficacy in RET-driven tumor xenografts upon multiday dosing in mice. The administration of 1 was well-tolerated at established efficacious doses (10 and 30 mg/kg, po, qd), and plasma exposure levels indicated a minimal risk of KDR or hERG inhibition in vivo, as evaluated by Miles assay and free plasma concentrations, respectively.

Circular RNA circDNA2 upregulates CCDC6 expression to promote the progression of gastric cancer via miR-149-5p suppression

Circular (circ)RNAs are widely involved in gastric cancer (GC) pathogenesis, and coiled-coil domain containing 6 (CCDC6) is a fused partner of multiple oncogenes; however, the underlying mechanisms of how circRNAs regulate CCDC6 expression in the progression and prognosis of GC remain unclear. Here, we discovered the circRNA derived from the DNA2 gene locus (circDNA2) through RNA sequencing. By performing quantitative real-time PCR and fluorescence in situ hybridization (FISH) assays with a human tissue microarray, circDNA2 was found to be highly expressed in GC tissues and associated with lymphatic invasion of GC patients. Knockdown of circDNA2 expression suppressed the proliferation of GC cells by reducing CCDC6 expression. Mechanistically, circDNA2 acted as a microRNA (miR)-149-5p sponge, which was confirmed to target CCDC6 by RNA pulldown and dual-luciferase reporter assays and rescue experiments. Both low miR-149-5p expression and high CCDC6 expression were related to unfavorable prognosis in GC patients. Moreover, GC patients with low miR-149-5p expression had shorter overall survival and a higher risk of chemotherapy resistance than those with high miR-149-5p expression. In summary, circDNA2 contributes to the growth and lymphatic metastasis of GC by upregulating CCDC6 expression by sponging miR-149-5p. The circDNA2/miR-149-5p/CCDC6 axis might be developed as a therapeutic target and prognostic indicator for GC.

RET Gene Fusions in Malignancies of the Thyroid and Other Tissues

Following the identification of the BCR-ABL1 (Breakpoint Cluster Region-ABelson murine Leukemia) fusion in chronic myelogenous leukemia, gene fusions generating chimeric oncoproteins have been recognized as common genomic structural variations in human malignancies. This is, in particular, a frequent mechanism in the oncogenic conversion of protein kinases. Gene fusion was the first mechanism identified for the oncogenic activation of the receptor tyrosine kinase RET (REarranged during Transfection), initially discovered in papillary thyroid carcinoma (PTC). More recently, the advent of highly sensitive massive parallel (next generation sequencing, NGS) sequencing of tumor DNA or cell-free (cfDNA) circulating tumor DNA, allowed for the detection of RET fusions in many other solid and hematopoietic malignancies. This review summarizes the role of RET fusions in the pathogenesis of human cancer.

Efficacy and Tolerability of Pyrazolo[1,5-a]pyrimidine RET Kinase Inhibitors for the Treatment of Lung Adenocarcinoma

RET (REarranged during Transfection) kinase gain-of-function aberrancies have been identified as potential oncogenic drivers in lung adenocarcinoma, along with several other cancer types, prompting the discovery and assessment of selective inhibitors. Internal mining and analysis of relevant kinase data informed the decision to investigate a pyrazolo[1,5-a]pyrimidine scaffold, where subsequent optimization led to the identification of compound WF-47-JS03 (1), a potent RET kinase inhibitor with >500-fold selectivity against KDR (Kinase insert Domain Receptor) in cellular assays. In subsequent mouse in vivo studies, compound 1 demonstrated effective brain penetration and was found to induce strong regression of RET-driven tumor xenografts at a well-tolerated dose (10 mg/kg, po, qd). Higher doses of 1, however, were poorly tolerated in mice, similar to other pyrazolo[1,5-a]pyrimidine compounds at or near the efficacious dose, and indicative of the narrow therapeutic windows seen with this scaffold.