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: A synergistic effect of etoposide and cyclosporin A was observed in a patient with acute T - lymphocytic leukemia in relapse .
### Output Text:
A synergistic effect of <span class="chemical">etoposide</span> and <span class="chemical">cyclosporin A</span> was observed in a patient with acute T - lymphocytic leukemia in relapse . 