22908
Gefitinib , a tyrosine kinase inhibitor of the epidermal growth factor receptor ( EGFR ) , has been used to treat numerous cancers ; however , evidence has shown that cancer cells can become resistant to gefitinib during therapy .
 Chemical: Gefitinib; Chemical: tyrosine; Chemical: gefitinib
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Gefitinib; Chemical: tyrosine; Chemical: gefitinib