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: All active treatments were associated with significantly reduced MSSBP and MSDBP during the core 8 - week study , with each monotherapy significantly contributing to the overall effect of combination therapy ( VAL and HCTZ , P < 0 . 001 ) .
### Output Text:
All active treatments were associated with significantly reduced MSSBP and MSDBP during the core 8 - week study , with each monotherapy significantly contributing to the overall effect of combination therapy ( <span class="chemical">VAL</span> and <span class="chemical">HCTZ</span> , P < 0 . 001 ) . 