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 phase I study to determine the maximum tolerated dose of paclitaxel ( Taxol ; Bristol - Myers Squibb Company , Princeton , NJ ) given as a 3 - hour infusion in combination with carboplatin administered every 21 days to women with advanced ovarian cancer , paclitaxel doses were escalated as follows : level 1 , 135 mg / m2 ; level 2 , 160 mg / m2 ; level 3 , 185 mg / m2 ; and level 4 , 210 mg / m2 .
### Output Text:
In a phase I study to determine the maximum tolerated dose of <span class="chemical">paclitaxel</span> ( <span class="chemical">Taxol</span> ; Bristol - Myers Squibb Company , Princeton , NJ ) given as a 3 - hour infusion in combination with <span class="chemical">carboplatin</span> administered every 21 days to women with advanced ovarian cancer , <span class="chemical">paclitaxel</span> doses were escalated as follows : level 1 , 135 mg / m2 ; level 2 , 160 mg / m2 ; level 3 , 185 mg / m2 ; and level 4 , 210 mg / m2 . 