Precision medicine and its implementation in patients with NTRK fusion genes: perspective from developing countries

Precision oncology is the field that places emphasis on the diagnosis and treatment of tumors that harbor specific genomic alterations susceptible to inhibition or modulation. Although most alterations are only present in a minority of patients, a substantial effect on survival can be observed in this subgroup. Mass genome sequencing has led to the identification of a specific driver in the translocations of the tropomyosin receptor kinase family (NTRK) in a subset of rare tumors both in children and in adults, and to the development and investigation of Larotrectinib. This medication was granted approval by the US Food and Drug Administration for NTRK-positive tumors, regardless of histology or age group, as such, larotrectinib was the first in its kind to be approved under the premise that molecular pattern is more important than histology in terms of therapeutic approach. It yielded significant results in disease control with good tolerability across a wide range of diseases including rare pediatric tumors, salivary gland tumors, gliomas, soft-tissue sarcomas, and thyroid carcinomas. In addition, and by taking different approaches in clinical trial design and conducting allocation based on biomarkers, the effects of target therapies can be isolated and quantified. Moreover, and considering developing nations and resource-limited settings, precision oncology could offer a tool to reduce cancer-related disability and hospital costs. In addition, developing nations also present patients with rare tumors that lack a chance of treatment, outside of clinical trials. This, in turn, offers the possibility for international collaboration, and contributes to employment, education, and health service provisions. The reviews of this paper are available via the supplemental material section.

New Treatment Options for ALK-Rearranged Non-Small Cell Lung Cancer

OPINION STATEMENT

ALK rearrangements are present in 3-5% of patients with non-small cell lung cancer (NSCLC) and after epidermal growth factor receptor (EGFR) mutations represent the second molecular target in NSCLC to be validated through phase III clinical trials. The PROFILE 1014 international multicentre phase III trial demonstrated the superiority of crizotinib over standard chemotherapy, establishing crizotinib as standard first-line therapy for patients with advanced ALK-positive NSCLC and indicating the requirement for ALK testing to guide selection of optimal first-line therapy for non-squamous NSCLC. Despite impressive and durable responses, progression on treatment reflecting the development of acquired resistance is inevitable. There are several mechanisms of resistance including ALK kinase mutation or copy number gain, activation of bypass pathways and potentially pharmacokinetic failure of therapy (most commonly in CNS). A broad array of newer generation ALK inhibitors are in development that appear effective in the crizotinib-resistant setting including in patients with intracranial progression. These agents, including ceritinib and alectinib, have a higher potency against ALK kinase than crizotinib, activity against mutations that confer resistance to crizotinib and potentially improved CNS penetration. While in selected patients, continued therapy with crizotinib after local ablative treatments of oligo-progressive systemic or CNS disease may be an option, for many patients use of a newer generation compound will be effective. First-line treatment with newer generation ALK inhibitors may have potential advantages over sequential treatment after crizotinib; however, the optimal sequence of therapy with ALK inhibitors has not been determined and is being explored in ongoing phase III studies.

Treating patients with ALK-positive non-small cell lung cancer: latest evidence and management strategy

Rearrangements in anaplastic lymphoma kinase (ALK) gene and echinoderm microtubule-associated protein-like 4 (EML4) gene were first described in a small portion of patients with non-small cell lung cancer (NSCLC) in 2007. Fluorescence in situ hybridization is used as the diagnostic test for detecting an EML4-ALK rearrangement. Crizotinib, an ALK inhibitor, is effective in treating advanced ALK-positive NSCLC, and the US Food and Drug Administration approved it for treating ALK-positive NSCLC in 2011. Several mechanisms of acquired resistance to crizotinib have recently been reported. Second-generation ALK inhibitors were designed to overcome these resistance mechanisms. Two of them, ceritinib and alectinib, were approved in 2014 for advanced ALK-positive NSCLC in the US and Japan, respectively. Heat shock protein 90 (Hsp90) inhibitors also showed activity against ALK-positive NSCLC. Here we review the recent development of crizotinib, ceritinib, alectinib and other second-generation ALK inhibitors as well as Hsp90 inhibitors. We also discuss management strategies for advanced ALK-positive NSCLC.

Mechanisms of Acquired Resistance to ALK Inhibitors and the Rationale for Treating ALK-positive Lung Cancer

The discovery of an echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) fusion gene led to improved clinical outcomes in patients with lung cancer after the development of the first ALK-targeting agent, crizotinib. Some second-generation ALK tyrosine kinase inhibitors (TKIs), which might be more potent than crizotinib or effective on crizotinib-resistant patients, have been developed. Although these ALK-TKIs show an excellent response initially, most patients eventually acquire resistance. Therefore, careful consideration of the resistance mechanisms might lead to superior therapeutic strategies. Here, we summarize the history of ALK-TKIs and their underlying resistance mechanisms in both the preclinical and clinical settings. In addition, we discuss potential future treatment strategies in ALK-TKI-naïve and -resistant patients with lung cancer harboring the EML4-ALK fusion gene.