Bill Cosby on Monday filed a defamation suit against seven women who have accused him of sexual assault or misconduct.

Cosby, 78, said in the lawsuit that the women made “malicious, opportunistic and false and defamatory accusations of sexual misconduct” against him.

Old allegations against Cosby were the subject of renewed attention last year. Since then, more than 50 women have come forward to accuse Cosby of sexual assault or misconduct.

The seven women named in Cosby’s lawsuit are part of a defamation lawsuit against him. Tamara Green, Therese Serignese and Linda Traitz filed suit against Cosby in 2014, with Louisa Moritz, Barbara Bowman, Joan Tarshis and Angela Leslie joining the suit in November.

Cosby’s lawsuit says that the women “knowingly published false statements and accusations” against him.

It also says that the women’s claims have negatively affected his existing business arrangements.

“Each counterclaim defendant induced both NBC and Netflix to postpone or cancel their contracts with Mr Cosby by engaging in a campaign to assassinate Mr Cosby’s reputation and character by willfully, maliciously, and falsely accusing Mr Cosby of multi-decade-old purported sexual misconduct in an opportunistic attempt to extract financial gain from their allegations,” the suit says.

Former supermodel Janice Dickinson has also filed a separate defamation suit against Cosby.

Documents from a 2005 civil lawsuit against Cosby were made public in July and included a testimony in which Cosby admitted to obtaining sedative drugs to to use on women he wanted to have sex with.

Cosby has never been charged with a crime.

His lawsuit was made public the same day that Boston University announced that it is the latest school to revoke an honorary degree it had awarded to Cosby.

“Mr Cosby’s admitted conduct, which the University learned about only after awarding him the degree, demonstrates that his character fails to reflect the integrity and virtues that the University values and esteems in members of its community, and in those persons the University holds up for this particular honor,” the school said in a statement.

Boston University awarded Cosby an honorary doctor of humane letters degree at the school’s May 2014 commencement ceremony. Universities in New York, Wisconsin, Rhode Island, Massachusetts and Pennsylvania have also rescinded honorary degrees they awarded to Cosby.