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: It may serve as an alternative to cisplatin - containing regimens ; however , it has to be considered that possibly HUS may occur .
### Output Text:
It may serve as an alternative to <span class="chemical">cisplatin</span> - containing regimens ; however , it has to be considered that possibly HUS may occur . 