Crizotinib
Crizotinib is a novel targeted anticancer agent for Non-Small-cell lung cancer.
Crizotinib is an oral kinase inhibitor approved for the treatment of Anaplastic lymphoma kinase non-Small-cell lung cancer.
Patients with ALK+ metastases have poor intracranial control relative to EGFR+ metastases, possibly because of limited intracranial penetration of crizotinib compared with estimated glomerular filtration rate inhibitors. Future investigations are warranted to determine the optimal management of ALK+ brain metastases with the introduction of second-generation ALK inhibitors 1).
Anaplastic lymphoma kinase (ALK)-rearranged non-small-cell lung cancer (NSCLC) is a distinct subtype with patients showing peculiar clinicopathological features and dramatic responses to the ALK tyrosine kinase inhibitor crizotinib. Patients with this cancer variant have a dismal prognosis and limited treatment options when it has progressed to intracranial metastases because of inadequate drug penetration into the central nervous system (CNS) 2).
Anaplastic lymphoma kinase (ALK) gene rearrangement was reported in 3%-7% of primary non-small-cell lung cancer (NSCLC) and its presence is commonly associated with adenocarcinoma (AD) type and non-smoking history. ALK tyrosine kinase inhibitors (TKIs) such as crizotinib, alectinib and ceritinib showed efficiency in patients with primary NSCLC harboring ALK gene rearrangement. Moreover, response to ALK TKIs was observed in central nervous system (CNS) metastatic lesions of NSCLC. However, there are no reports concerning the frequency of ALK rearrangement in CNS metastases. We assessed the frequency of ALK abnormalities in 145 formalin fixed paraffin embedded (FFPE) tissue samples from CNS metastases of NSCLC using immunohistochemical (IHC) automated staining (BenchMark GX, Ventana, USA) and fluorescence in situ hybridization (FISH) technique (Abbot Molecular, USA). The studied group was heterogeneous in terms of histopathology and smoking status. ALK abnormalities were detected in 4.8% (7/145) of CNS metastases. ALK abnormalities were observed in six AD (7.5%; 6/80) and in single patients with adenosuqamous lung carcinoma. Analysis of clinical and demographic factors indicated that expression of abnormal ALK was significantly more frequently observed (P = 0.0002; χ2 = 16.783) in former-smokers. Comparison of IHC and FISH results showed some discrepancies, which were caused by unspecific staining of macrophages and glial/nerve cells, which constitute the background of CNS tissues. Their results indicate high frequency of ALK gene rearrangement in CNS metastatic sites of NSCLC that are in line with prior studies concerning evaluation of the presence of ALK abnormalities in such patients. However, they showed that assessment of ALK by IHC and FISH methods in CNS tissues require additional standardizations 3).
Case series
A study included 34 previously untreated ALK-positive NSCLC patients with three or fewer intracranial metastases. Of these patients, 13 received oral alectinib 600 mg twice daily, and 21 received oral crizotinib 250 mg twice daily, until progressive disease, unacceptable toxicity, or death. All intracranial metastases were treated with craniotomy, CyberKnife, or both.
Results: Median overall progression-free survival (PFS) was 32.8 months (95% CI 24.4-41.2 months) in patients treated with alectinib and 8.0 months (95% CI 7.3-8.7 months) in patients treated with crizotinib. Median PFS of brain lesions was not yet reached with alectinib (95% CI 30.1 months-not estimated) and was 8.5 months (95% CI 7.2-12.3 months) with crizotinib. Median PFS of lung lesions was 38.5 months (95% CI 27.5-49.5 months) with alectinib and 9.2 months (95% CI 7.4-11.0 months) with crizotinib. Median overall survival was not yet reached with alectinib (95% CI 31.0 months-not estimated) and 30.3 months (95% CI 27.3-37.1 months) with crizotinib.
Conclusion: Compared with crizotinib, alectinib showed superior efficacy and lower toxicity in the treatment of ALK-positive patients with NSCLC and symptomatic and synchronic brain metastases. The inclusion of intracranial therapies such as craniotomy or CyberKnife further improved the brain PFS and overall survival of these patients 4).
Choi et al. performed a retrospective review of 29 patients who underwent a total of 51 GKS procedures for BM while continuing on crizotinib. We compared 2 groups on the basis of the number of BMs: oligometastases (≤5) and polymetastases (>5).
The actuarial 1- and 2-year overall survival rates from initial GKS were 73.5% and 42.6%, respectively. The estimated local progression-free survival (PFS) rates of the oligometastases group were 91.8% at 6 months and 84.2% at 12 months, whereas the local PFS rates of the polymetastases group at 6 and 12 months were 91.6% and 58.2%, respectively (P = 0.153). The estimated distant PFS rates of the oligometastases group were 50.7% at 6 months and 20.3% at 12 months, whereas the distant PFS rates of the polymetastases group were 32.7% at 6 months and only 6.5% at 12 months (P = 0.029).
GKS combined with crizotinib showed effective local tumor control and excellent outcome, especially in oligometastases. However, distant progression of BM during crizotinib after GKS occurred in most of the cases within a year. Thus brain surveillance after GKS is important for adequate and timely salvage treatment even when extracranial disease is well controlled by crizotinib 5).
Case reports
A case of a 17-year-old male with metastatic treatment-naïve ALK-positive adenocarcinoma. He was treated with crizotinib and obtained a prolonged response with PFS of 33 months.
Conclusion: Crizotinib can be extremely effective in adolescents with treatment-naïve ALK-positive NSCLC but fail to prevent a central nervous system relapse. Resistance mechanisms need to be investigated 6)
2017
In a NSCLC patient with multiple intracranial metastases, Wang et al. administered high-dose pulsatile crizotinib therapy (1000 mg/d) on a one-day-on/one-day-off basis. A significant central nervous system (CNS) response was achieved, and time to neurological progression was prolonged to 6 months.
High-dose pulsatile therapy may be an effective dosing strategy for crizotinib in NSCLC showing progression to metastases in the brain 7).
Inflammatory myofibroblastic tumors (IMT) of the central nervous system (CNS) are rare entities that have a predilection for local recurrences. Approximately half of the inflammatory myofibroblastic tumors contain translocations that result in the over-expression of the anaplastic lymphoma kinase (ALK) gene. We hereby present the case of a patient diagnosed with a left parieto-occipital IMT that recurred after multiple surgeries and radiotherapy. Immuno-histochemical examination of the tumor demonstrated ALK overexpression and the presence of an ALK rearrangement observed in lung cancers. The patient was subsequently started on an ALK inhibitor. A response evaluation criteria in solid tumors (RECIST) partial response was observed by the seventh month of ALK inhibition and the tumor remained in control for 14 months. The current case reiterates the activity of ALK inhibitors within the CNS and suggests that radiotherapy may potentiate the permeability of ALK inhibitors in CNS tumors addicted to ALK signalling 8).