Evaluation of the In Vivo Efficacy of the JAK Inhibitor AZD1480 in Uterine Leiomyomas Using a Patient-derived Xenograft Murine Model

Uterine leiomyomas are common noncancerous hormonally-dependent neoplasms comprised of uterine smooth-muscle cells and fibroblasts. Despite their significant impact on morbidity, effective non-hormonal medical treatments are lacking. In vitro studies have identified the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway as a promising target in leiomyoma cells. Our objective was to evaluate the efficacy of AZD1480, a JAK 1/2 inhibitor, in treating uterine leiomyomas using a patient-derived xenograft murine model. Ovariectomized immunodeficient mice received an estrogen and progesterone pellet and were subsequently implanted with human leiomyoma tissue surgically resected from premenopausal women not on hormonal medication. Mice were divided into treatment (n = 6) and vehicle control (n = 6) groups receiving either 50 mg/kg of AZD1480 or vehicle via oral gavage for 5 days/week for 28 days. Our results demonstrate a significant AZD1480-mediated reduction in both xenograft volume (59.5% vs. 0.3%; treated vs. control, p < .0001) and weight (56.0% vs. 31.2%; p = 0.03) compared to controls. Moreover, xenografts from the treated group exhibited a significant decrease in cell density(p = 0.01). Levels of pSTAT3-positive cells (4.1% vs. 10.3%), Ki67-positive cells (4.1% vs. 6.5%), and fibrillar collagen (19.8% vs. 29.5%) declined but did not reach statistical significance, whereas AZD1480 treatment significantly reduced blood vessel formation in the xenografts (20.1 vs 45.6 per FOV; p = 0.01). These findings suggest JAK inhibition as a potential treatment for uterine leiomyomas by targeting angiogenesis. However, further studies are warranted to explore alternative JAK inhibitors, examine downstream effects, optimize dosing, and establish clinical efficacy and safety.