AIDS activist Sean Sasser passed away on Wednesday.  He was 44.

According to a press release from AIDS United, Sasser died after a brief but difficult battle with mesothelioma, a rare cancer that attacks the lungs.

Sasser and Pedro Zamora held a commitment ceremony during MTV's reality series The Real World: San Francisco. The 1994 season was considered groundbreaking for including Zamora, an openly gay HIV-positive AIDS educator, as a regular cast member. Zamora died on November 11, 1994, the day after the final episode of Real World aired.

After Real World, Sasser continued to advocate on behalf of HIV-positive individuals. His life partner, Michael Kaplan, runs the D.C.-based non-profit AIDS United.

“While we and the world have known Sean as a prominent AIDS activist, the AIDS United family also has known Sean as the devoted spouse of Michael Kaplan, who supported and accompanied him as the couple made a significant life transition from Portland, OR to Washington D.C. when we recruited Michael to take the helm of AIDS United in December, 2012,” the group said in a written statement. “We shared Michael's pride as Sean's success as a celebrated pastry chef just continued to grow after their move to the District. We will always be grateful for Sean's support of Michael in Michael's new and often-demanding role as President and CEO. And we will certainly miss the generous samplings of his magnificent pastry creations that he occasionally shared with the AIDS United offices.”