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: Acute encephalopathy and cerebral vasospasm after multiagent chemotherapy including PEG - asparaginase and intrathecal cytarabine for the treatment of acute lymphoblastic leukemia .
### Output Text:
Acute encephalopathy and cerebral vasospasm after multiagent chemotherapy including <span class="chemical">PEG - asparaginase</span> and intrathecal <span class="chemical">cytarabine</span> for the treatment of acute lymphoblastic leukemia . 