1638
The available PET data imply that an effective therapeutic enzyme for treatment of cocaine abuse could be an exogenous cocaine - metabolizing enzyme with a catalytic activity against ( - ) - cocaine comparable to that of wild - type BChE against ( + ) - cocaine .
 cocaine, cocaine, ( - ) - cocaine, ( + ) - cocaine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 cocaine, cocaine, ( - ) - cocaine, ( + ) - cocaine