14901
SAR studies led to the discovery of the highly potent and selective CCR1 antagonist 14 ( CCR1 binding IC ( 50 ) = 4 nM using [ ( 125 ) I ] - CCL3 as the chemokine ligand ) .
 [ ( 125 ) I ] - CCL3
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 [ ( 125 ) I ] - CCL3