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: End - diastolic ( ED ) and end - systolic ( ES ) LV diameters / BW significantly increased , whereas LV FS was decreased after 9 weeks in the DOX group ( p < 0 . 001 ) .
### Output Text:
End - diastolic ( ED ) and end - systolic ( ES ) LV diameters / BW significantly increased , whereas LV FS was decreased after 9 weeks in the <span class="chemical">DOX</span> group ( p < 0 . 001 ) . 