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: The object of the meeting was to analyse existing data , both published or available , in the European Group for Blood and Marrow Transplantation autoimmune disease database , and to propose a safe approach to such patients .
### Output Text:
The object of the meeting was to analyse existing data , both published or available , in the European Group for Blood and Marrow Transplantation autoimmune disease database , and to propose a safe approach to such patients . 