What to do after resistance to crizotinib/Xalkori

Crizotinib/Crizotinib has achieved significant efficacy in patients with ALK-positive non-small cell lung cancer (NSCLC), but most patients will develop drug resistance after a period of treatment. The resistance mechanisms mainly include two types:ALK-dependent resistance and ALK-independent resistance.

ALK-dependent resistance is mainly due to secondary mutations in the ALK gene, resulting in changes in the binding site of crizotinib, thereby reducing the inhibitory effect of the drug. Common secondary mutations include G1202R, I1171X and L1196M. These mutations restore ALK kinase activity and tumor cells regain their ability to proliferate.

ALK-independent drug resistance is due to tumor cells bypassing the ALK pathway by activating other signaling pathways, thereby continuing to grow and spread. Common mechanisms include MET gene amplification, KRAS mutation, BRAF V600E mutation, etc. These changes make tumor cells no longer dependent on the ALK pathway, causing crizotinib to be ineffective.

Faced with crizotinib resistance, a variety of clinical strategies have been adopted to overcome resistance. First, liquid biopsy (ctDNA analysis) can monitor molecular changes in tumors in real time, identify drug resistance mechanisms, and provide guidance for subsequent treatment. Secondly, according to different resistance mechanisms, select appropriate next-generation ALK inhibitors (such as alectinib, brigatinib, lorlatinib, etc.) for treatment. These drugs have stronger inhibitory effects on certain types of ALK mutations and can effectively overcome crizotinib resistance.

In addition, combination therapy is also an effective strategy. For example, combined use of MEK inhibitors (such as trametinib) can inhibit the MAPK signaling pathway and enhance the anti-tumor effect of ALK inhibitors. Studies have shown that the combined use of ALK inhibitors and MEK inhibitors can delay the development of drug resistance in some patients.

Reference materials:https://go.drugbank.com/drugs/DB08865