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: Patients had a significant probability of improving from < VGPR before consolidation therapy to > VGPR after consolidation therapy ( p = 0 . 041 ) .
### Output Text:
Patients had a significant probability of improving from < VGPR before consolidation therapy to > VGPR after consolidation therapy ( p = 0 . 041 ) . 