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: Patients who had ARI after high - dose melphalan underwent dialysis more often ( P = 0 . 007 ) , and had a worse 1 - year survival ( P = 0 . 03 ) .
### Output Text:
Patients who had ARI after high - dose <span class="chemical">melphalan</span> underwent dialysis more often ( P = 0 . 007 ) , and had a worse 1 - year survival ( P = 0 . 03 ) . 