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: Brain natriuretic peptide is a predictor of anthracycline - induced cardiotoxicity .
### Output Text:
Brain natriuretic peptide is a predictor of <span class="chemical">anthracycline</span> - induced cardiotoxicity . 