Ocular and orbital side effects of ALK inhibitors: a review article

ALK inhibitors are a new group of tyrosine kinase inhibitors, highly efficient in the treatment of non-small-cell lung carcinoma. However, these targeted therapies can induce various adverse effects, including ocular toxicity. To date, few articles reporting ophthalmological side effects of ALK inhibitors have been published. In this review, we aim to describe the different side effects and to collect information regarding the causes behind the discrepancy between the reported rates of visual disorders. Frequent ocular side effects of ALK inhibitors included flashes, post-flashbulb effect, stripes, photopsia, accommodation disorder, presbyopia, reduced visual acuity and blurred vision. Optic neuropathy, vitreous floaters, diplopia, cataract and macular edema were also reported.

Towards manageable toxicities from targeted lung cancer treatment

Targeted agents are now considered standard of care for patients whose tumors possess a sensitizing mutation in EGFR or ALK rearrangement. As the toxicity profiles of these agents differ significantly from that of cytotoxic chemotherapy, physicians need to be cognizant of the clinically relevant adverse events and manage them aggressively. Early recognition of these toxicities is vital to ensure medication compliance and maintain quality of life for patients. As more novel agents enter the treatment armamentarium, such as third-generation EGFR and ALK inhibitors, it will be important for physicians to understand class-specific toxicities and rare but serious side effects associated with these drugs.

Crizotinib: a review of its use in the treatment of anaplastic lymphoma kinase-positive, advanced non-small cell lung cancer

Crizotinib (Xalkori(®)) is an orally active, small molecule inhibitor of multiple receptor tyrosine kinases, including anaplastic lymphoma kinase (ALK), c-Met/hepatocyte growth factor receptor and c-ros oncogene 1. In the EU, crizotinib has been conditionally approved for the treatment of adults with previously treated, ALK-positive, advanced non-small cell lung cancer (NSCLC). This approval has been based on objective response rate and tolerability data from two ongoing phase I/II studies (PROFILE 1001 and PROFILE 1005); these results have been substantiated and extended by findings from an ongoing phase III study (PROFILE 1007) in patients with ALK-positive, advanced NSCLC who had received one prior platinum-based regimen. Those treated with crizotinib experienced significant improvements in progression-free survival, objective response rate, lung cancer symptoms and global quality of life, as compared with those treated with standard second-line chemotherapy (pemetrexed or docetaxel). The relative survival benefit with crizotinib is unclear, however, as the data are still immature and likely to be confounded by the high cross-over rate among chemotherapy recipients. Crizotinib treatment was generally well tolerated in the three PROFILE studies, with liver transaminase elevations and neutropenia being the most common grade 3 or 4 adverse events. Crizotinib is the standard of care in terms of the treatment of patients with ALK-positive, advanced NSCLC; while the current EU approval is for second (or subsequent)-line use only, the first-line use of the drug is being evaluated in ongoing phase III studies. Key issues relating to the use of crizotinib in clinical practice include identifying the small subset of eligible patients, the almost inevitable development of resistance and the high cost of treatment.

Crizotinib

Crizotinib is an ATP-competitive small-molecule inhibitor of the receptor tyrosine kinases (RTK) c-Met, anaplastic lymphoma kinase (ALK), and ROS1. There is convincing clinical evidence for the effectiveness in non-small-cell lung cancer (NSCLC) harboring EML4-ALK rearrangements resulting in constitutional activation of the ALK-RTK. The drug is approved for this entity, which represents no more than 3-5% of all NSCLC. However, in this population, impressive response rates are generated. The same seems to be true for ROS-1 rearrangements; however, these only occur in approximately 1% of all NSCLC. The role in c-Met altered cancers needs to be determined. Toxicities include visual impairment, nausea, peripheral edema, QT-prolongation, and liver enzyme elevation. Also, the occurrence of renal cysts is reported. Fluorescence in situ hybridization (FISH) detecting the ALK rearrangement has to be performed on tumor tissue to predict crizotinib efficacy. The role of immunohistochemistry in this setting needs to be determined. It has high concordance with FISH results when strongly positive or completely negative. The high efficacy of crizotinib in ALK- and ROS-positive lung cancer as new molecular targets beside the epidermal growth factor receptor (EGFR) underscores the importance of molecular typing in NSCLC.