Jack Schlossberg has spoken out about the impact of his older sister and “best friend” Tatiana’s death.
The 35-year-old granddaughter of the late President John F. Kennedy and Jacqueline Kennedy Onassis died in December 2025, after being diagnosed withacute myeloid leukemia, an aggressive form of blood cancer, with a mutation called Inversion 3.
During a new interview with Vanity Fair, Jack opened up about managing his grief over the past few months, confessing that he doesn’t think he’ll ever “process” it.
“The world will never be the same for me, not only since she passed away, but since she was diagnosed with cancer about two years ago,” the 33-year-old, who’s running for Congress in New York’s 12th District, said. “She was my best friend. We could finish each other’s sentences. And no one loved me or was a bigger fan of me of anyone else than my sister.
“So I miss her all the time. Every day I think about her. But it also really does motivate me to do everything I can with every waking moment I have, because I realize it could have just as easily been me, and I have an obligation to her, not just to myself, to make the most out of my precious life and all that I’ve been given in this life to give back to others and make sure that we can fund cures for the type of cancer that took her life, and for other types of cancer.”
The son of Caroline Kennedy and Edwin Schlossberg, concluded: “And so it’s made me all the more motivated, engaged, and focused on making the most out of my life, and I think that there’s no higher calling than, than public service, and to me, I think politics is a noble profession, and one that I would be fantastic at serving this district as.
“So she wanted me to win, and I intend to honor her by doing just that.”
The JFK Library Foundation announced Tatiana’s death in a statement in December. She revealed her cancer diagnosis in a New Yorker essay published November 22, 2025, the 62nd anniversary of her grandfather’s assassination.
She received the diagnosis in May 2024, after the birth of her second child, Josephine, with husband George Moran. The couple, who tied the knot in 2017, also have a three-year-old son, Edwin.
Tatiana ultimately underwent initial rounds of chemo before receiving a stem cell transplant from her older sister, Rose Schlossberg, who was a match. The transplant was a success and put her in remission, but the cancer soon returned.
She tried different treatment options, however, “during the latest clinical trial, my doctor told me that he could keep me alive for a year, maybe,” she wrote.
In a March interview on CBS Sunday Morning, Jack said he spoke to his sister about his run for Congress before she died.
“The last thing that she said to me was, ‘You better win,’” Jack said.
