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: Animals that were given the HPMA copolymer conjugates containing DOX exhibited no significant change in cardiac output throughout the study ( P less than 0 . 05 ) .
### Output Text:
Animals that were given the <span class="chemical">HPMA</span> copolymer conjugates containing <span class="chemical">DOX</span> exhibited no significant change in cardiac output throughout the study ( P less than 0 . 05 ) . 