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: RESULTS : Of the 80 patients studied , ARI developed in 18 . 8 % of the patients after high - dose melphalan .
### Output Text:
RESULTS : Of the 80 patients studied , ARI developed in 18 . 8 % of the patients after high - dose <span class="chemical">melphalan</span> . 