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 , we retrospectively analyzed the safety and efficacy of combination regimen of bortezomib , thalidomide , and dexamethasone ( VTD ) as consolidation therapy in 24 Japanese patients with newly diagnosed MM .
### Output Text:
In this study , we retrospectively analyzed the safety and efficacy of combination regimen of <span class="chemical">bortezomib</span> , <span class="chemical">thalidomide</span> , and <span class="chemical">dexamethasone</span> ( VTD ) as consolidation therapy in 24 Japanese patients with newly diagnosed MM . 