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: In this study , cancer patients who have solid and hematological malignancies with chronic HBV infection received the antiviral agent lamivudine prior and during CT compared with historical control group who did not receive lamivudine .
### Output Text:
In this study , cancer patients who have solid and hematological malignancies with chronic HBV infection received the antiviral agent <span class="chemical">lamivudine</span> prior and during CT compared with historical control group who did not receive <span class="chemical">lamivudine</span> . 