Acquired Tertiary MET Resistance (MET D1228N and a Novel LSM8-MET Fusion) to Selpercatinib and Capmatinib in a Patient With KIF5B-RET-positive NSCLC With Secondary MET Amplification as Initial Resistance to Selpercatinib

Adaptive Darwinian off-target resistance mechanisms to selective RET inhibition in RET driven cancer

Patients treated with RET protein tyrosine kinase inhibitors (TKIs) selpercatinib or pralsetinib develop RET TKI resistance by secondary RET mutations or alterative oncogenes, of which alterative oncogenes pose a greater challenge for disease management because of multiple potential mechanisms and the unclear tolerability of drug combinations. A patient with metastatic medullary thyroid carcinoma (MTC) harboring a RET activation loop D898_E901del mutation was treated with selpercatinib. Molecular alterations were monitored with tissue biopsies and cfDNA during the treatment. The selpercatinib-responsive MTC progressed with an acquired ETV6::NTRK3 fusion, which was controlled by selpercatinib plus the NTRK inhibitor larotrectinib. Subsequently, tumor progressed with an acquired EML4::ALK fusion. Combination of selpercatinib with the dual NTRK/ALK inhibitor entrectinib reduced the tumor burden, which was followed by appearance of NTRK3 solvent-front G623R mutation. Preclinical experiments validated selpercatinib plus larotrectinib or entrectinib inhibited RET/NTRK3 dependent cells, whereas selpercatinib plus entrectinib was necessary to inhibit cells with RET/NTRK3/ALK triple alterations or a mixture of cell population carrying these genetic alterations. Thus, RET-altered MTC adapted to selpercatinib and larotrectinib with acquisition of ETV6::NTRK3 and EML4::ALK oncogenes can be managed by combination of selpercatinib and entrectinib providing proof-of-concept of urgency of incorporating molecular profiling in real-time and personalized N-of-1 care transcending one-size-fits-all approach.

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

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

Targeting MET: Discovery of Small Molecule Inhibitors as Non-Small Cell Lung Cancer Therapy

MET has been considered as a promising drug target for the treatment of MET-dependent diseases, particularly non-small cell lung cancer (NSCLC). Small molecule MET inhibitors with mainly three types of binding modes (Ia/Ib, II, and III) have been developed. In this Review, we provide an overview of the structural features, activation mechanism, and dysregulation pathway of MET and summarize progress on the development and discovery strategies utilized for MET inhibitors as well as mechanisms of acquired resistance to current approved inhibitors. The insights will accelerate discovery of new generation MET inhibitors to overcome clinical acquired resistance.

Identification of LSM family members as potential chemoresistance predictive and therapeutic biomarkers for gastric cancer

Introduction

The Like-Smith (LSM) family plays a critical role in the progression of several cancers. However, the function of LSMs in chemoresistance of gastric cancer (GC) is still elusive.

Methods

The Cancer Genome Atlas (TCGA) database, Gene Expression Omnibus (GEO) database and Tumor Immune Estimation Resource Analysis (TIMER) were utilized to analyze the expression, prognostic value and immune infiltration of LSMs in GC patients. Moreover, qPCR and immunohistochemistry (IHC) experiment were conducted with clinical samples.

Results

The expression of LSMs was upregulated in GC tissues and most of LSMs were negatively correlated with overall survival of GC patients with 5-fluorouracil (5-FU) treatment. We further revealed that LSM5, 7 and 8 were hub genes of GEO (GSE14210). Besides, the qPCR results demonstrated that a higher level of LSM5 and LSM8 was associated with 5-FU chemoresistance in GC. Moreover, both TIMER and IHC revealed that a lower expression of LSM5 and LSM8 was correlated with high infiltration of T cells, regulatory T cells, B cells, macrophages, and neutrophils.

Discussion

Our study systematically investigated the expression pattern and biological features of LSM family members in GC, and identified LSM5 and LSM8 as potential biomarkers in GC with 5-FU chemotherapy.

ALK-positive lung cancer: a moving target

Anaplastic lymphoma kinase (ALK) is a potent oncogenic driver in lung cancer. ALK tyrosine kinase inhibitors yield significant benefit in patients with ALK fusion-positive (ALK+) lung cancers; yet the durability of response is limited by drug resistance. Elucidation of on-target resistance mechanisms has facilitated the development of next-generation ALK inhibitors, but overcoming ALK-independent resistance mechanisms remains a challenge. In this Review, we discuss the molecular underpinnings of acquired resistance to ALK-directed therapy and highlight new treatment approaches aimed at inducing long-term remission in ALK+ disease.

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.

Small-molecule inhibitors, immune checkpoint inhibitors, and more: FDA-approved novel therapeutic drugs for solid tumors from 1991 to 2021

The United States Food and Drug Administration (US FDA) has always been a forerunner in drug evaluation and supervision. Over the past 31 years, 1050 drugs (excluding vaccines, cell-based therapies, and gene therapy products) have been approved as new molecular entities (NMEs) or biologics license applications (BLAs). A total of 228 of these 1050 drugs were identified as cancer therapeutics or cancer-related drugs, and 120 of them were classified as therapeutic drugs for solid tumors according to their initial indications. These drugs have evolved from small molecules with broad-spectrum antitumor properties in the early stage to monoclonal antibodies (mAbs) and antibody‒drug conjugates (ADCs) with a more precise targeting effect during the most recent decade. These drugs have extended indications for other malignancies, constituting a cancer treatment system for monotherapy or combined therapy. However, the available targets are still mainly limited to receptor tyrosine kinases (RTKs), restricting the development of antitumor drugs. In this review, these 120 drugs are summarized and classified according to the initial indications, characteristics, or functions. Additionally, RTK-targeted therapies and immune checkpoint-based immunotherapies are also discussed. Our analysis of existing challenges and potential opportunities in drug development may advance solid tumor treatment in the future.

Poor response to selpercatinib plus crizotinib in a rearranged during transfection fusion-positive patient with acquired selpercatinib-resistant MNNG HOS transforming amplification: a case report

Selpercatinib has been approved by most major regulatory bodies in 2020 and become the standard therapy for rearranged during transfection ( RET )-rearranged nonsmall-cell lung cancer (NSCLC). Knowledge is limited regarding mechanisms of resistance to selpercatinib and effective treatment. One study identified MNNG HOS transforming ( MET ) amplification as intrinsic or secondary resistance mechanism from four patients, and three of them showed ~40% tumor reduction when treated with selpercatinib plus crizotinib. We report a 30-year-old female nonsmoker diagnosed in 2019 with stage IV lung adenocarcinoma harboring KIF5B-RET and a novel FOXD1-RET fusion. Frontline therapy consisted of bevacizumab combined with pemetrexed and carboplatin and achieved a progression-free survival (PFS) of 14 months with best response of stable disease. The patient then enrolled in the LIBRETTO-321 trial (NCT03157129) and started selpercatinib, which elicited a PFS of 9 months with best response of partial response. MNNG HOS transforming ( MET ) amplification was subsequently detected upon progression on selpercatinib, and the patient was placed on third-line treatment with selpercatinib plus crizotinib. However, her health deteriorated rapidly and died of cancer 4 months later. We provided additional evidence supporting MET amplification as an acquired mechanism of resistance to selective RET inhibition. In addition, the apparent lack of response to selpercatinib plus crizotinib in this case highlights the need for future cohort studies for examining the value of combining RET and MET inhibitors in treating RET -rearranged, MET -amplified NSCLC.

Selpercatinib in RET-fusion positive metastatic non-small cell lung cancer: achievements and gray areas

INTRODUCTION

Selpercatinib is a RET selective tyrosine kinase inhibitor with nanomolar potency against diverse RET alterations, including fusions, activating point mutations, and acquired resistance mutations. Rearranged during transfection (RET) gene is a validated target in non-small-cell lung cancer (NSCLC). Selpercatinib is currently approved for adult patients with metastatic RET fusion-positive NSCLC.

AREAS COVERED

This review summarizes the efficacy and safety data of selpercatinib in the treatment landscape of RET fusion-positive NSCLC.

EXPERT OPINION

Globally considered, selpercatinib is an optimal treatment choice, in terms of both (systemic and intracranial) efficacy and safety, in patients affected by advanced NSCLC harboring RET fusions as a driver mechanism. Future challenges include the identification of the most appropriate placement for selpercatinib in the treatment algorithm of RET fusion-positive NSCLC (including early stages), the clarification of resistance mechanisms, as well as of its role in EGFR-mutant NSCLC undergoing progression during osimertinib driven by RET alterations.

Foretinib can overcome common on-target resistance mutations after capmatinib/tepotinib treatment in NSCLCs with MET exon 14 skipping mutation

Background

Capmatinib and tepotinib are guideline-recommended front-line treatments for non-small-cell lung cancer (NSCLC) patients with MET exon 14 skipping mutations (METex14). However, the emergence of acquired resistance to capmatinib/tepotinib is almost inevitable partially due to D1228X or Y1230X secondary mutations of the MET. In this study, we explored agents that are active against both D1228X and Y1230X MET to propose an ideal sequential treatment after capmatinib/tepotinib treatment failure in NSCLC patients with METex14.

Methods

The inhibitory effects of 300 drugs, including 33 MET-TKIs, were screened in Ba/F3 cells carrying METex14 plus MET D1228A/Y secondary mutations. The screen revealed four-candidate type II MET-TKIs (altiratinib, CEP-40783, foretinib and sitravatinib). Therefore, we performed further growth inhibitory assays using these four MET-TKIs plus cabozantinib and merestinib in Ba/F3 cells carrying MET D1228A/E/G/H/N/V/Y or Y1230C/D/H/N/S secondary mutations. We also performed analyses using Hs746t cell models carrying METex14 (with mutant allele amplification) with/without D1228X or Y1230X in vitro and in vivo to confirm the findings. Furthermore, molecular dynamics (MD) simulations were carried out to examine differences in binding between type II MET-TKIs.

Results

All 6 type II MET-TKIs were active against Y1230X secondary mutations. However, among these 6 agents, only foretinib showed potent activity against D1228X secondary mutations of the MET in the Ba/F3 cell and Hs746t in vitro model and Hs746t in vivo model, and CEP-40783 and altiratinib demonstrated some activity. MD analysis suggested that the long tail of foretinib plays an important role in binding D1228X MET through interaction with a residue at the solvent front (G1163). Tertiary G1163X mutations, together with L1195F/I and F1200I/L, occurred as acquired resistance mechanisms to the second-line treatment foretinib in Ba/F3 cell models.

Conclusions

The type II MET-TKI foretinib may be an appropriate second-line treatment for NSCLCs carrying METex14 after campatinib/tepotinib treatment failure by secondary mutations at residue D1228 or Y1230.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01299-z.

Molecular Testing and Treatment Strategies in RET-Rearranged NSCLC Patients: Stay on Target to Look Forward

RET alterations are recognized as key oncogenic drivers in different cancer types, including non-small cell lung cancer (NSCLC). Multikinase inhibitors (MKIs) with anti-RET activities resulted in variable efficacy with significant toxicities because of low target specificity. Selective RET kinase inhibitors, such as pralsetinib and selepercatinib, demonstrated high efficacy and favorable tolerability in advanced RET-rearranged NSCLC patients, leading to their introduction in the clinical setting. Among the different approaches available for the identification of RET rearrangements, next-generation sequencing (NGS) assays present substantial advantages in terms of turnaround time and diagnostic accuracy, even if potentially limited by accessibility issues. The recent advent of novel effective targeted therapies raises several questions regarding the emergence of resistance mechanisms and the potential ways to prevent/overcome them. In this review, we discuss molecular testing and treatment strategies to manage RET fusion positive NSCLC patients with a focus on resistance mechanisms and future perspectives in this rapidly evolving scenario.

Precision therapy for RET-altered cancers with RET inhibitors

Rearranged during transfection (RET) is involved in the physiological development of some organ systems. Activating RET alterations via either gene fusions or point mutations are potent oncogenic drivers in non-small cell lung cancer, thyroid cancer, and in multiple diverse cancers. RET-altered cancers were initially treated with multikinase inhibitors (MKIs). The efficacy of MKIs was modest at the expense of notable toxicities from their off-target activity. Recently, highly potent and RET-specific inhibitors selpercatinib and pralsetinib were successfully translated to the clinic and FDA approved. We summarize the current state-of-the-art therapeutics with preclinical and clinical insights of these novel RET inhibitors, acquired resistance mechanisms, and future outlooks.

Will the clinical development of 4th-generation "double mutant active" ALK TKIs (TPX-0131 and NVL-655) change the future treatment paradigm of ALK+ NSCLC?

Our current treatment paradigm of advanced anaplastic lymphoma kinase fusion (ALK+) non-small cell lung cancer (NSCLC) classifies the six currently approved ALK tyrosine kinase inhibitors (TKIs) into three generations. The 2nd-generation (2G) and 3rd-generation (3G) ALK TKIs are all "single mutant active" with varying potencies across a wide spectrum of acquired single ALK resistance mutations. There is a vigorous debate among clinicians which is the best upfront ALK TKI is for the first-line (1L) treatment of ALK+ NSCLC and the subsequent sequencing strategies whether it should be based on the presence of specific on-target ALK resistance mutations or not. Regardless, sequential use of "single mutant active" ALK TKIs will eventually lead to double ALK resistance mutations in cis. This has led to the creation of fourth generation (4G) "double mutant active" ALK TKIs such as TPX-0131 and NVL-655. We discuss the critical properties 4G ALK TKIs must possess to be clinically successful. We proposed conceptual first-line, second-line, and molecularly-based third-line registrational randomized clinical trials designed for these 4G ALK TKIs. How these 4G ALK TKIs would be used in the future will depend on which line of treatment the clinical trial design(s) is adopted provided the trial is positive. If approved, 4G ALK TKIs may usher in a new treatment paradigm for advanced ALK+ NSCLC that is based on classifying ALK TKIs based on the intrinsic functional capabilities ("singe mutant active" versus "double mutant active") rather than the loosely-defined "generational" (first-, second-,third-,fourth-) classification and avoid the current clinical approaches of seemingly random sequential use of 2G and 3G ALK TKIs.