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: After 154 courses of therapy , the median dose intensity was 131 mg / m ( 2 ) for paclitaxel ( 97 . 3 % ) , 117 mg / m ( 2 ) for cisplatin ( 97 . 3 % ) , and 1378 mg / m ( 2 ) for gemcitabine ( 86 . 2 % ) .
### Output Text:
After 154 courses of therapy , the median dose intensity was 131 mg / m ( 2 ) for <span class="chemical">paclitaxel</span> ( 97 . 3 % ) , 117 mg / m ( 2 ) for <span class="chemical">cisplatin</span> ( 97 . 3 % ) , and 1378 mg / m ( 2 ) for <span class="chemical">gemcitabine</span> ( 86 . 2 % ) . 