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A 40-year - old man with relapsing - remitting multiple sclerosis ( MS ) developed primary central nervous system lymphoma ( PCNSL ) after having received 21 doses of natalizumab monotherapy .
 PCNSL, natalizumab; primary central nervous system lymphoma, natalizumab
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: adverse effect 
Text: {0} 
Answer:
 PCNSL, natalizumab; primary central nervous system lymphoma, natalizumab