Cellectar Biosciences Inc. said the U.S. Food and Drug Administration granted the third rare pediatric disease designation to its CLR 131 drug for treating a rare type of pediatric cancer.

The latest rare pediatric disease status for CLR 131 is for Ewing's sarcoma, a type of tumor that forms in the bone or soft tissue and is most common in adolescents and young children.

CLR 131 previously received the designation for treating neuroblastoma and rhabdomyosarcoma.

Neuroblastoma is a type of cancer that forms from immature nerve cells and most often occurs in children younger than five years old. Meanwhile, rhabdomyosarcoma is a cancer that forms in the soft tissues in a type of muscle called striated muscle.

The drug was also awarded orphan drug status for Ewing's sarcoma in July.

Cellectar intends to examine CLR 131 in a phase 1 study to treat children with Ewing's sarcoma; rhabdomyosarcoma; osteosarcoma, a cancer of the bone that usually affects the large bones of the arm or leg; neuroblastoma; high-grade gliomas, which are tumors in the brain's glial cells; and lymphomas, which are cancers that begin in cells of the immune system.