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: Thus , temsirolimus reduced tumor burden through associated cytostatic and anti - angiogenic effects . This dual effect of temsirolimus on tumor tissue could contribute to its recently reported efficiency in refractory MCL resistant to conventional chemotherapy .
### Output Text:
Thus , <span class="chemical">temsirolimus</span> reduced tumor burden through associated cytostatic and anti - angiogenic effects . This dual effect of <span class="chemical">temsirolimus</span> on tumor tissue could contribute to its recently reported efficiency in refractory MCL resistant to conventional chemotherapy . 