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: We report a case of acute renal failure after HD - MTX therapy in a patient with ileostomy , The patient was a 3 - year - old boy who had received a living - related liver transplantation for congenital biliary atresia .
### Output Text:
We report a case of acute renal failure after HD - <span class="chemical">MTX</span> therapy in a patient with ileostomy , The patient was a 3 - year - old boy who had received a living - related liver transplantation for congenital biliary atresia . 