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 : 24 patients were evaluable for response with one partial response of 11 months duration of a patient with hepatic and pulmonary metastases ( 4 % ) , one minor response , and 2 patients stable for over 6 months .
### Output Text:
RESULTS : 24 patients were evaluable for response with one partial response of 11 months duration of a patient with hepatic and pulmonary metastases ( 4 % ) , one minor response , and 2 patients stable for over 6 months . 