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: The DLT included hypercalcemia , and may be predicted by serum cis - RA levels .
### Output Text:
The DLT included hypercalcemia , and may be predicted by serum <span class="chemical">cis - RA</span> levels . 