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: Neurologic toxicities have been described with IT - methotrexate , IT - cytosine arabinoside and IT - TSPA .
### Output Text:
Neurologic toxicities have been described with IT - <span class="chemical">methotrexate</span> , IT - <span class="chemical">cytosine arabinoside</span> and IT - <span class="chemical">TSPA</span> . 