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: Our experience supports the safety of giving AraG as salvage therapy in synchrony with etoposide and cyclophosphamide , although neurological toxicity must be closely monitored .
### Output Text:
Our experience supports the safety of giving <span class="chemical">AraG</span> as salvage therapy in synchrony with <span class="chemical">etoposide</span> and <span class="chemical">cyclophosphamide</span> , although neurological toxicity must be closely monitored . 