In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Following GEM - P , 5 - year progression - free survival was 46 % ( 95 % confidence interval ( CI ) , 30 - 62 % ) and 5 - year overall survival was 59 % ( 95 % CI , 43 - 74 % ) .
### Output Text:
Following <span class="chemical">GEM</span> - P , 5 - year progression - free survival was 46 % ( 95 % confidence interval ( CI ) , 30 - 62 % ) and 5 - year overall survival was 59 % ( 95 % CI , 43 - 74 % ) . 