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: In spite of the fact that TSPA is a useful IT agent , its combination with MTX , ara - C and radiotherapy could cause severe neurotoxicity .
### Output Text:
In spite of the fact that <span class="chemical">TSPA</span> is a useful IT agent , its combination with <span class="chemical">MTX</span> , <span class="chemical">ara - C</span> and radiotherapy could cause severe neurotoxicity . 