Kate Middleton and Prince William are mourning the death of Liz Hatton, the teenage cancer patient who inspired the royals after meeting her in October. Hatton passed away Wednesday at the age of 17 after battling a rare form of cancer.

The royal couple signed the post “W & C” — the initials of their first names, William and Catherine — to signify that the message came directly from them.

Princess Kate and Prince William said they are "so sorry" after a "brave and humble" teenage photographer they worked with died from cancer. The Princess of Wales hugged Liz Hatton during a meeting in Windsor in October after inviting the 17-year-old to take pictures of the Prince of Wales during an investiture ceremony.