It is not possible for a Maledictus to be cured as she is bound by a blood curse that one of her ancestors received. However, since the Maledictus exists in the realm of magic, it is possible that a cure existed in this world. However, the only known Maledictus in the Harry Potter universe was Nagini, who was once a human woman but eventually turned into a snake forever, and she was not cured of her condition, as is evident from the plot of the books. Therefore, it is possible that a cure did not exist, at least not at the time she completely transformed.