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: The indications for switch were chronic CsA or Tac nephrotoxicity ( 12 ) , acute CsA or Tac toxicity ( 3 ) , severe facial dysmorphism ( 2 ) , posttransplant lymphoproliferative disorder ( PTLD ) in remission ( 2 ) , and hepatotoxicity in 1 .
### Output Text:
The indications for switch were chronic <span class="chemical">CsA</span> or <span class="chemical">Tac</span> nephrotoxicity ( 12 ) , acute <span class="chemical">CsA</span> or <span class="chemical">Tac</span> toxicity ( 3 ) , severe facial dysmorphism ( 2 ) , posttransplant lymphoproliferative disorder ( PTLD ) in remission ( 2 ) , and hepatotoxicity in 1 . 