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: CONCLUSION : Myocet improves the therapeutic index of doxorubicin by significantly reducing cardiotoxicity and grade 4 neutropenia and provides comparable antitumor efficacy , when used in combination with cyclophosphamide as first - line therapy for MBC .
### Output Text:
CONCLUSION : <span class="chemical">Myocet</span> improves the therapeutic index of <span class="chemical">doxorubicin</span> by significantly reducing cardiotoxicity and grade 4 neutropenia and provides comparable antitumor efficacy , when used in combination with <span class="chemical">cyclophosphamide</span> as first - line therapy for MBC . 