Phase 1/2 study of alectinib in RET-rearranged previously-treated non-small cell lung cancer (ALL-RET)

RET Inhibitors in RET Fusion-Positive Lung Cancers: Past, Present, and Future

While activating RET fusions are identified in various cancers, lung cancer represents the most common RET fusion-positive tumor. The clinical drug development of RET inhibitors in RET fusion-positive lung cancers naturally began after RET fusions were first identified in patient tumor samples in 2011, and thereafter paralleled drug development in RET fusion-positive thyroid cancers. Multikinase inhibitors were initially tested with limited efficacy and substantial toxicity. RET inhibitors were then designed with improved selectivity, central nervous system penetrance, and activity against RET fusions and most RET mutations, including resistance mutations. Owing their success to these rationally designed features, the first-generation selective RET tyrosine kinase inhibitors (TKIs) had higher response rates, more durable disease control, and an improved safety profile compared to the multikinase inhibitors. This led to lung and thyroid cancer, and later tumor-agnostic regulatory approvals. While next-generation RET TKIs were designed to abrogate uncommon on-target (e.g., solvent front mutation) resistance to selpercatinib and pralsetinib, many of these drugs lacked the selectivity of the first-generation TKIs, raising the question of what the future holds for drug development in RET-dependent cancers.

Utility of bronchoscopically obtained frozen cytology pellets for next-generation sequencing

BACKGROUND

Next-generation sequencing (NGS) is essential for lung cancer treatment. It is important to collect sufficient tissue specimens, but sometimes we cannot obtain large enough samples for NGS analysis. We investigated the yield of NGS analysis by frozen cytology pellets using an Oncomine Comprehensive Assay or Oncomine Precision Assay.

METHODS

We retrospectively enrolled patients with lung cancer who underwent bronchoscopy at Kobe University Hospital and were enrolled in the Lung Cancer Genomic Screening Project for Individualized Medicine. We investigated the amount of extracted DNA and RNA and determined the NGS success rates. We also compared the amount of DNA and RNA by bronchoscopy methods. To create the frozen cytology pellets, we first effectively collected the cells and then quickly centrifuged and cryopreserved them.

RESULTS

A total of 132 patients were enrolled in this study between May 2016 and December 2022; of them, 75 were subjected to frozen cytology pellet examinations and 57 were subjected to frozen tissue examinations. The amount of DNA and RNA obtained by frozen cytology pellets was nearly equivalent to frozen tissues. Frozen cytology pellets collected by endobronchial ultrasound-guided transbronchial needle aspiration yielded significantly more DNA than those collected by transbronchial biopsy methods. (P < 0.01) In RNA content, cytology pellets were not inferior to frozen tissue. The success rate of NGS analysis with frozen cytology pellet specimens was comparable to the success rate of NGS analysis with frozen tissue specimens.

CONCLUSIONS

Our study showed that frozen cytology pellets may have equivalent diagnostic value to frozen tissue for NGS analyses. Bronchial cytology specimens are usually used only for cytology, but NGS analysis is possible if enough cells are collected to create pellet specimens. In particular, the frozen cytology pellets obtained by endobronchial ultrasound-guided transbronchial needle aspiration yielded sufficient amounts of DNA.

TRIAL REGISTRATION

This was registered with the University Medical Hospital Information Network in Japan (UMINCTR registration no. UMIN000052050).

High-dose alectinib for RET fusion-positive non-small cell lung cancer in the Blood First Assay Screening Trial

Introduction

This paper presents results from Cohort B (rearranged during transfection [RET], fusion-positive) of the Blood First Assay Screening Trial in patients with advanced non-small cell lung cancer (NSCLC) screened for genetic alterations using blood-based next-generation sequencing.

Material and methods

Adults with advanced RET fusion-positive NSCLC received alectinib 900 mg twice daily (BID) in Phase I. Enrolment closed prematurely with Phase II uninitiated.

Results

Among eight treated patients, confirmed best overall responses in evaluable patients were stable disease (4/5) and progressive disease (1/5). One dose-limiting toxicity (death, unknown cause) was considered by the investigator to be related to treatment and underlying disease. Serious adverse events (SAEs) occurred in five patients, and SAEs that may be related to treatment occurred in two patients.

Conclusions

Alectinib showed limited activity in advanced RET fusion-positive NSCLC, and further investigation was not conducted due to the development of selective RET inhibitors pralsetinib and selpercatinib. No new safety signals were observed, and the safety profile of alectinib was in line with previous reports at the 600 mg BID dose.

Anaplastic Lymphoma Kinase Inhibitor-Induced Neutropenia: A Systematic Review

Lung cancers with ALK rearrangement represent less than 5% of all lung cancers. ALK inhibitors are currently used to treat first-line metastatic non-small cell lung cancer with ALK rearrangement. Compared to chemotherapy, ALK inhibitors have improved progression-free survival, overall survival, and quality of life for patients. The results of several phase 3 studies with a follow-up of over 6 years suggest that the life expectancy of these patients treated with targeted therapies is significantly higher than 5 years and could approach 10 years. Nevertheless, these treatments induce haematological toxicities, including neutropenia. Few data are available on neutropenia induced by ALK inhibitors and on the pathophysiological mechanism and therapeutic adaptations necessary to continue the treatment. Given the high efficacy of these treatments, managing side effects to avoid treatment interruptions is essential. Here, we have reviewed the data from published clinical studies and case reports to provide an overview of neutropenia induced by ALK inhibitors.

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.

An update on Alectinib: a first line treatment for ALK-positive advanced lung cancer

INTRODUCTION

Alectinib is a second-generation, anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI) for the treatment of ALK+ non-small cell lung cancer (NSCLC) and is able to induce significant and durable CNS responses. However, long-term use of alectinib has been clinically reported to cause some serious and even life-threatening adverse events. There are currently no effective interventions for its adverse events, and this undoubtedly leads to delays in patient treatment and limits its long-term clinical use.

AREAS COVERED

Based on the clinical trials conducted so far, we summarize the efficacy and adverse events that occurred, especially those related to cardiovascular disorders, gastrointestinal disorders, hepatobiliary disorders, musculoskeletal and connective tissue disorders, skin and subcutaneous tissue disorders, and respiratory disorders. The factors that may influence alectinib selection are also described. Findings are based on a PubMed literature search of clinical and basic science research papers spanning 1998-2023.

EXPERT OPINION

The significant prolongation of patient survival compared with first-generation ALK inhibitor suggests its potential as a first-line treatment for the NSCLC, but the severe adverse events of alectinib limit its long-term clinical use. Future research should focus on the exact mechanisms of these toxicities, how to alleviate the adverse events caused by alectinib clinically, and the development of next-generation drugs with reduced toxicities.

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.

Alectinib for the treatment of pretreated RET-rearranged advanced NSCLC: Results of the ETOP ALERT-lung trial

BACKGROUND

Alectinib, a highly selective next generation ALK-inhibitor, has exhibited potent anti-tumour activity in RET-rearranged NSCLC in the preclinical stage.

METHODS

ALERT-lung is a single-arm, phase II trial evaluating the activity of alectinib for the treatment of pretreated RET-rearranged advanced NSCLC. Alectinib was administered orally, 600 mg, twice per day until progression, refusal or unacceptable toxicity (treatment could continue beyond progression, if patient was deriving clinical benefit). Patient recruitment closed prematurely due to discouraging results for alectinib in a phase I/II study in the same indication.

RESULTS

All 14 patients who enrolled until the premature accrual closure, received at lease one dose of alectinib. Among them, median age was 61 years, majority (71 %) was female, never smokers, of ECOG PS 1. No objective response (complete or partial response) was recorded. Of the 13 evaluable patients, three (23 %) achieved and maintained disease stabilisation for 24 weeks. Up to 31 March 2021 (median follow-up 15.9 months), 12 PFS-events (92 %) were observed, with median PFS of 3.7 months (95 % C.I.: 1.8 - 7.3 months). Overall, three deaths (23 %) were reported. Seven patients (50 %) experienced grade ≥ 3 adverse events, while three discontinued treatment due to erythema multiforme of grade 3, related to alectinib. No treatment-related serious adverse event was reported.

CONCLUSIONS

Accrual into our trial was terminated early in response to other reports of limited activity of alectinib in patients with RET-fusion NSCLC and the emergence of more potent selective RET-inhibitors. Also in our trial, alectinib did not show the expected potential for anti-tumour activity in NSCLC.

RET signaling pathway and RET inhibitors in human cancer

Rearranged during transfection (RET) receptor tyrosine kinase was first identified over thirty years ago as a novel transforming gene. Since its discovery and subsequent pathway characterization, RET alterations have been identified in numerous cancer types and are most prevalent in thyroid carcinomas and non-small cell lung cancer (NSCLC). In other tumor types such as breast cancer and salivary gland carcinomas, RET alterations can be found at lower frequencies. Aberrant RET activity is associated with poor prognosis of thyroid and lung carcinoma patients, and is strongly correlated with increased risk of distant metastases. RET aberrations encompass a variety of genomic or proteomic alterations, most of which confer constitutive activation of RET. Activating RET alterations, such as point mutations or gene fusions, enhance activity of signaling pathways downstream of RET, namely PI3K/AKT, RAS/RAF, MAPK, and PLCγ pathways, to promote cell proliferation, growth, and survival. Given the important role that mutant RET plays in metastatic cancers, significant efforts have been made in developing inhibitors against RET kinase activity. These efforts have led to FDA approval of Selpercatinib and Pralsetinib for NSCLC, as well as, additional selective RET inhibitors in preclinical and clinical testing. This review covers the current biological understanding of RET signaling, the impact of RET hyperactivity on tumor progression in multiple tumor types, and RET inhibitors with promising preclinical and clinical efficacy.

Selective RET inhibitors shift the treatment pattern of RET fusion-positive NSCLC and improve survival outcomes

PURPOSE

Rearranged during transfection (RET) fusions are important genetic drivers in non-small cell lung cancer (NSCLC). Selective RET inhibitors are setting a new paradigm in RET-driven NSCLC. However, the real-world treatment patterns, outcomes and toxicity remain largely unknown.

METHODS

Data from RET fusion-positive NSCLC patients treated in our centre were retrospectively analysed. Of them, patients diagnosed before and after August 2018 were included in analysis of treatment patterns; and patients received selective RET inhibitors were eligible for analysis of adverse events (AEs).

RESULTS

Patients diagnosed before August 2018 (n = 30) predominantly received chemotherapy and immunotherapy (83%) as initial therapy, while patients diagnosed after August 2018 (n = 39) mainly received selective RET inhibitors (38.5% at first-line; 50.0% at second-line). In the total 69 patients, overall survival (OS) was prolonged in patients treated with selective RET inhibitors versus untreated patients (median 34.3 versus 17.5 months; p = 0.002) during a median follow-up of 28.7 months. But there was no difference between patients treated with immunotherapy versus untreated patients. In the 38 patients received selective RET inhibition, median progression-free survival (PFS) was 11.9 months. AEs ≥ grade 3 occurred in 42.1% patients and were not associated with PFS (p = 0.63) or OS (p = 0.60). Haematological toxicity ≥ grade 3 occurred in 31.6% patients and was the leading cause of drug discontinuation.

CONCLUSION

Selective RET inhibitors are increasingly being adopted into clinical practice and are associated with improved OS. However, treatment-related ≥ grade 3 AEs, especially haematologic AEs, occur frequently in real-world setting.

Severe Skin Toxicity Caused by Sequential Anti-PD-1 Antibody and Alectinib in Non-small-cell Lung Cancer: A Report of Two Cases and a Literature Review

Immune checkpoint inhibitors (ICIs) have demonstrated marked efficacy in some cancer patients, but they may cause various severe immune-related adverse events. Alectinib is a second-generation anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitor (TKI) approved for ALK-rearranged non-small-cell lung cancer (NSCLC). Alectinib is said to be safer than other TKIs. We conducted an investigator-initiated trial of alectinib, which also has RET kinase-inhibitory activity, against RET-rearranged NSCLC. Two RET-rearranged NSCLC patients experienced severe skin toxicity with alectinib after first undergoing anti-PD-1 antibody treatment with an ICI. These findings suggest that we should carefully follow patients for adverse effects of targeted drugs following ICI treatment.

Advances in the treatment of RET-fusion-positive lung cancer

Ten years ago, RET-fusions were discovered as oncogenic drivers and potential drug targets in approximately 1% of metastatic lung adenocarcinomas. Several multikinase inhibitors were tested in clinical trials, however, their antitumor activity was limited. Recently, two selective and potent RET-inhibitors were approved for the treatment of patients with metastatic RET-fusion-positive lung cancer (RET-NSCLC). Here, we discuss the two RET-inhibitors selpercatinib and pralsetinib, and the management of patients with RET-fusion positive NSCLC.