Sean Sasser, Pedro Zamora's boyfriend on "The Real World: San Francisco", has died at the age of 44, castmate Judd Winick confirmed Tuesday.

Winick sent out a tweet which said, "Our friend Sean Sasser has died. Our love goes out to his family & husband Michael. We will miss u so much."

The cause of death was mesothelioma, a rare form of lung cancer, his partner Michael Kaplan told Queerty.

Sasser, an AIDS activist who himself was HIV positive, and Zamora dated until Zamora's death from AIDS in 1994 at the age of 22.