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 10 days of treatment , he developed acute renal failure that was completely reversible after complete remission of APL was achieved and therapy discontinued .
### Output Text:
After 10 days of treatment , he developed acute renal failure that was completely reversible after complete remission of APL was achieved and therapy discontinued . 