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: After recovery of his renal function , we could safely treat the patient with HD - MTX therapy by controlling drainage from ileostoma with total parenteral nutrition .
### Output Text:
After recovery of his renal function , we could safely treat the patient with HD - <span class="chemical">MTX</span> therapy by controlling drainage from ileostoma with total parenteral nutrition . 