The daughters of the late Sen. Edward Kennedy and former Vice President Walter Mondale have both died at age 51 in unrelated circumstances.

Eleanor Mondale, a journalist, announced in 2009 that she was being treated for brain cancer, and stepped down from her broadcast duties at a Minneapolis radio station.

She had been active in her father’s political campaigns, including his unsuccessful 2002 bid to replace the late-Sen. Paul Wellstone (D-Minn.) after Wellstone was killed in a plane crash during his re-election campaign.

The former vice president, in an email to friends, said, “Joan and I must report that our wonderful daughter, Eleanor Mondale Poling, after her long and gutsy battle against cancer, went up to heaven last night to be with her angel,” the Associated Press reported.

Kara Kennedy died Friday night after suffering a heart attack while working out at a Washington, D.C., gym. She had also battled cancer, but after surgery to remove a lung tumor, was declared cancer-free. Her brother, former Rep. Patrick Kennedy (D-R.I.), said her cancer treatment “took quite a toll on her and weakened her physically” and “her heart gave out,” according to the Associated Press.

Sen. Kennedy, (D-Mass.) developed a brain tumor and died in 2009 at age 77.