What is the target detection analysis of crizotinib in lung cancer treatment?

In the treatment of lung cancer, the target detection analysis of crizotinib mainly focuses on the detection of anaplastic lymphoma kinase (ALK) and ROS1 fusion genes. These tests are critical in determining whether a patient is a candidate for treatment with crizotinib.

ALKfusion gene is an important molecular marker in non-small cell lung cancer (NSCLC), and its positive rate is about 3%-5%. ALKThe generation of fusion genes is usually due to chromosomal translocations that cause the ALK gene to fuse with other genes (such as EML4) to form a fusion protein with sustained kinase activity. This fusion protein can activate downstream signaling pathways and promote the proliferation and survival of tumor cells.

Fluorescence in situ hybridization (FISH) is one of the common methods for detecting ALK fusion genes. FISH technology can directly observe specific gene segments on chromosomes to determine whether there is an ALK fusion gene.

Immunohistochemistry (IHC) indirectly infers the presence of the ALK fusion gene by detecting the expression of ALK protein in tumor cells. Although the sensitivity and specificity of IHC may be slightly lower than FISH, it is easier to operate and relatively less expensive.

Reverse transcription-Polymerase chain reaction (RT-PCR) can detect the ALK fusion gene's mRNA expression to determine whether there is ALKFusion genes. This method has high sensitivity and specificity, but the operation is relatively complicated.

ROS1 Fusion gene is also an important molecular marker in non-small cell lung cancer, and its positive rate is relatively low. The production mechanism of ROS1 fusion gene is similar to that of ALK fusion gene. It is also caused by chromosomal translocation that ROS1 gene fuses with other genes.

The detection methods of ROS1fusion genes are usually similar to ALKfusion genes, including FISH, IHC and RT-PCR etc. However, due to the low positive rate of the ROS1 fusion gene, more sensitive and specific detection methods may be needed in practical applications.

Through the target detection analysis of crizotinib, doctors can determine whether the patient has the ALK or ROS1 fusion gene, thereby determining whether the patient is suitable for treatment with crizotinib. This is of great significance for improving treatment effects and reducing unnecessary drug side effects.