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: Median number of courses of MFL regimen given was six and the median cumulative dose of mitoxantrone was 68 . 35 mg / m2 .
### Output Text:
Median number of courses of <span class="chemical">MFL regimen</span> given was six and the median cumulative dose of <span class="chemical">mitoxantrone</span> was 68 . 35 mg / m2 . 