18210
Furthermore , the lack of comprehensive structure - activity relationship data increases the burden on appropriately designed human clinical studies with predefined acceptance criteria to demonstrate the absence of clinically meaningful differences between the biosimilar and reference product .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None