A comprehensive study of the rare diseases and conditions targeted by orphan drug designations and approvals over the forty years of the Orphan Drug Act

Table 2 Top 25 diseases with the most orphan drug designations, 1983–2022

Disease	Therapeutic area	Designations	Initial orphan drug approvals
Malignant pancreatic neoplasm	Oncology	185	4
Acute myeloid leukemia	Oncology	183	14
Multiple myeloma	Oncology	130	19
Glioma	Oncology	129	4
Metastatic melanoma	Oncology	120	16
Amyotrophic lateral sclerosis	Neurology	119	5
Cystic fibrosis	Pulmonary	108	8
HIV infectious disease*	Infectious Diseases	92	23
Ovarian cancer*	Oncology	91	8
Hepatocellular carcinoma	Oncology	89	11
Gastric cancer	Oncology	80	4
Glioblastoma	Oncology	78	0
Idiopathic pulmonary fibrosis	Pulmonary	76	2
Sickle cell disease	Hematology	68	5
Graft versus host disease	Transplant	63	3
Duchenne muscular dystrophy	Neurology	63	5
Pulmonary arterial hypertension	Vascular	58	9
B-cell chronic lymphocytic leukemia	Oncology	57	12
Soft tissue sarcoma	Oncology	56	6
Acute lymphoblastic leukemia	Oncology	55	8
Solid organ transplant rejection	Transplant	49	7
Myelodysplastic syndrome	Oncology	49	5
Huntington disease	Neurology	46	2
Small cell lung carcinoma	Oncology	43	5
Systemic sclerosis	Rheumatology	42	1

*No longer considered a rare disease by FDA as total disease prevalence is currently calculated to be greater than 200,000 affected people in the US

ISSN: 1750-1172