Vanda Pharmaceuticals has announced that the US Food and Drug Administration (FDA) has granted Orphan Drug Designation for VGT-1849A, a selective antisense oligonucleotide (ASO)-based JAK2 inhibitor for the treatment of polycythemia vera (PV), a form of a rare hematologic malignancy that is estimated to affect 1 in 2000 Americans.1

PV is a chronic myeloproliferative disorder characterized by aberrant hematopoiesis of myeloid lineage with exuberant red cell production and increased release of pro-inflammatory cytokines. More than 95% of PV patients harbor the JAK2 V617F gain-of-function mutation leading to aberrant JAK2 production.2

Inhibiting JAK2 acts to suppress hematopoiesis, consequently reducing red blood cell, neutrophil, platelet, and lymphocyte production. JAK2 inhibitors have been shown to be efficacious in treating various JAK-dependent hematologic malignancies, including the treatment of PV. By selective reduction of JAK2 levels, the ASO VGT-1849A has the potential to reduce JAK2V617F-driven pathogenic signaling, ultimately suppressing the malignant proliferation and survival of hematopoietic cells.

Currently available small molecule inhibitors targeting the JAK2 protein kinase, such as Jakafi®, Inrebic®, Ojjaara®, and Vonjo®, lack sole selectivity for the target protein, which can result in off target effects. The adverse side effects that may occur from JAK inhibition emphasize the importance of selectively targeting JAK2 while avoiding inhibition of other JAK family members. By specifically targeting JAK2, Vanda seeks to reduce the risk of infection and toxic effects that are seen with inhibitors also blocking JAK1, JAK3, TYK2, or other kinases outside of the JAK family.

If approved, VGT-1849A could offer targeted efficacy with an improved safety profile and convenient dosing.

"This orphan designation for VGT-1849A is an important milestone in precision medicine-based therapeutics in the space of hematological malignancies. This milestone marks the second precision medicine therapeutic for Vanda following the development of VCA-894A for Charcot-Marie-Tooth3 that is expected to begin clinical testing in the coming months," said Mihael H. Polymeropoulos, MD, Vanda's President, CEO and Chairman of the Board.

VGT-1849A is a novel ASO treatment candidate for PV and other JAK2-driven hematologic malignancies. By selectively targeting JAK2, VGT-1849A reduces downstream signaling and JAK2V617F-driven autonomous cell proliferation, without any off-target kinase effects. The ability of VGT-1849A to reduce JAK2 activity may alleviate the disease burden that patients with PV face with a favorable safety profile, resulting in a higher quality of life for patients.