Question: When ceritinib used instead of crizotinib?

Context:
Ceritinib is a second-generation ALK inhibitor that has demonstrated activity in crizotinib-resistant patients, becoming a promising treatment option in this population. 
Ceritinib is approved for the treatment of ALK-positive metastatic NSCLC in patients who are intolerant to or have progressed despite therapy with crizotinib. 
Ceritinib has activity in crizotinib-resistant and crizotinib-naïve patients and appears to be a viable alternative for ALK-positive NSCLC.
In this review, we aim to present the current knowledge on acquired resistance of crizotinib known as a first-in-class ALK inhibitor and potential solutions to improve the cost-effectiveness, and to review the difference between ceritinib and crizotinib; preclinical data and results of the elegant early clinical trial of ceritinib which promoted its accelerated approval, pharmacokinetics, safety profile, and tolerability, the updated results (eg, efficacy on brain metastases), and robust design of ongoing phase II/III trials, and future directions of ceritinib to be a potent alternative to crizotinib for ALK-rearranged non-small-cell lung cancer are also presented.
Altogether, our results demonstrate that ceritinib can overcome crizotinib resistance, consistent with clinical data showing marked efficacy of ceritinib in patients with crizotinib-resistant disease.
Preclinical data showed impressive antitumor activity against crizotinib-resistant clones, and based on available data, ceritinib could represent a suitable option in crizotinib-resistant NSCLC.
The ALK inhibitor ceritinib overcomes crizotinib resistance in non-small cell lung cancer.
Ceritinib (LDK378): a potent alternative to crizotinib for ALK-rearranged non-small-cell lung cancer.
However, we observed that ceritinib did not overcome two crizotinib-resistant ALK mutations, G1202R and F1174C, and one of these mutations was identified in 5 of 11 biopsies from patients with acquired resistance to ceritinib. Altogether, our results demonstrate that ceritinib can overcome crizotinib resistance, consistent with clinical data showing marked efficacy of ceritinib in patients with crizotinib-resistant disease.SIGNIFICANCE: The second-generation ALK inhibitor ceritinib can overcome several crizotinib-resistant mutations and is potent against several in vitro and in vivo laboratory models of acquired resistance to crizotinib. These findings provide the molecular basis for the marked clinical activity of ceritinib in patients with ALK-positive NSCLC with crizotinib-resistant disease. 
However, we observed that ceritinib did not overcome two crizotinib-resistant ALK mutations, G1202R and F1174C, and one of these mutations was identified in 5 of 11 biopsies from patients with acquired resistance to ceritinib. Altogether, our results demonstrate that ceritinib can overcome crizotinib resistance, consistent with clinical data showing marked efficacy of ceritinib in patients with crizotinib-resistant disease.
Altogether, our results demonstrate that ceritinib can overcome crizotinib resistance, consistent with clinical data showing marked efficacy of ceritinib in patients with crizotinib-resistant disease.  The second-generation ALK inhibitor ceritinib can overcome several crizotinib-resistant mutations and is potent against several in vitro and in vivo laboratory models of acquired resistance to crizotinib.
The accelerated approval of potent ALK inhibitors, such as crizotinib and more recently ceritinib (LDK378), based on the well designed phase I/II trials has been a landmark success in clinical cancer research and contributes a new era of oncogenic targeted therapy characterized by elegant clinical trial design. In this review, we aim to present the current knowledge on acquired resistance of crizotinib known as a first-in-class ALK inhibitor and potential solutions to improve the cost-effectiveness, and to review the difference between ceritinib and crizotinib; preclinical data and results of the elegant early clinical trial of ceritinib which promoted its accelerated approval, pharmacokinetics, safety profile, and tolerability, the updated results (eg, efficacy on brain metastases), and robust design of ongoing phase II/III trials, and future directions of ceritinib to be a potent alternative to crizotinib for ALK-rearranged non-small-cell lung cancer are also presented.
The second-generation ALK inhibitor ceritinib can overcome several crizotinib-resistant mutations and is potent against several in vitro and in vivo laboratory models of acquired resistance to crizotinib. These findings provide the molecular basis for the marked clinical activity of ceritinib in patients with ALK-positive NSCLC with crizotinib-resistant disease.
In this review, we aim to present the current knowledge on acquired resistance of crizotinib known as a first-in-class ALK inhibitor and potential solutions to improve the cost-effectiveness, and to review the difference between ceritinib and crizotinib; preclinical data and results of the elegant early clinical trial of ceritinib which promoted its accelerated approval, pharmacokinetics, safety profile, and tolerability, the updated results (eg, efficacy on brain metastases), and robust design of ongoing phase II/III trials, and future directions of ceritinib to be a potent alternative to crizotinib for ALK-rearranged non-small-cell lung cancer are also presented.  Copyright © 2015 Elsevier Inc.

Answer: Ceritinib is approved for the treatment of ALK-positive metastatic NSCLC patients that are crizotinib-resistant and crizotinib-naïve.
Exact answer: crizotinib-resistant ALK-positive metastatic NSCLC patients, crizotinib-naïve ALK-positive metastatic NSCLC patients