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: Vinorelbine - related cardiac events concern about 1 % of treated patients in clinical trials .
### Output Text:
<span class="chemical">Vinorelbine</span> - related cardiac events concern about 1 % of treated patients in clinical trials . 