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 concomitant administration of etoposide and cyclosporin A resulted in eradication of hitherto refractory leukemic infiltration of bone marrow .
### Output Text:
The concomitant administration of <span class="chemical">etoposide</span> and <span class="chemical">cyclosporin A</span> resulted in eradication of hitherto refractory leukemic infiltration of bone marrow . 