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 a previous phase II study with 3 - weekly bolus 5 - FU , FA and mitomycin C ( MMC ) we found a low toxicity rate and response rates comparable to those of regimens such as ELF , FAM or FAMTX , and a promising median overall survival .
### Output Text:
In a previous phase II study with 3 - weekly bolus <span class="chemical">5 - FU</span> , <span class="chemical">FA</span> and <span class="chemical">mitomycin C</span> ( <span class="chemical">MMC</span> ) we found a low toxicity rate and response rates comparable to those of regimens such as ELF , FAM or FAMTX , and a promising median overall survival . 