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: Hypertension and the combination of bevacizumab / irinotecan may be additional risk factors for CIN development .
### Output Text:
Hypertension and the combination of <span class="chemical">bevacizumab</span> / <span class="chemical">irinotecan</span> may be additional risk factors for CIN development . 