O-266 Anti-angiogenic therapy as treatment for adenomyosis in mice

Abstract Study question What is the effect of anti-angiogenic therapy on adenomyosis in mice Summary answer Commencing treatment at six weeks with angiogenesis inhibitor axitinib successfully reduced the severity of adenomyosis by approximately 50% at 9 weeks. What is known already Adenomyosis is a gynecological disorder characterized by abnormal uterine bleeding, dysmenorrhea, pelvic pain and subfertility. Increased expression of angiogenic markers, as well as increased microvascular density (MVD) in adenomyosis suggest a pivotal role for angiogenesis in the pathophysiology of adenomyosis, which presents an opportunity for treatment. Study design, size, duration The effect of angiogenesis inhibition was studied in a tamoxifen-induced adenomyosis mouse model. 102 Mice received oral treatment with axitinib 3 mg/kg (‘dose I/AX3 treatment group’, n = 34), axitinib 25 mg/kg (‘dose II/AX25 treatment group’ n = 34), or with vehicle-only (‘placebo group’, n = 34) from week 6 until week 9. After termination of the mice at week 9, all uteri were analyzed for the presence of adenomyosis. Participants/materials, setting, methods The prevalence and severity of adenomyosis were assessed by; (i) grade of adenomyosis (0/1/2/3), based on the depth of endometrial gland infiltration into the myometrium in H&E-stained sections, (ii) percentage of adenomyosis-affected tissue in vimentin-stained sections and (iii) degree of myometrium that is affected in α-SMA-stained sections. The adenomyosis severity index was calculated by multiplying mean grade/mouse with the percentage affected surface area. Changes in angiogenesis-related gene expression were evaluated using real-time quantitative PCR. Main results and the role of chance 101 mice completed adenomyosis induction and could be analyzed. The prevalence of adenomyosis was 30/33 (90.0%) in dose I (3mg/kg), 29/34 (85.3%) in dose II (25mg/kg) and 30/34 (88.2%) in placebo treated mice (p=0.78). The prevalence of high grade (2/3) adenomyosis was significantly lower in mice treated with axitinib dose II (N = 19, 55.9%) than in the placebo group (N = 27, 79.4%, p<0.05). The grade of adenomyosis per mouse after treatment was 0.7 point lower in the groups treated with axitinib dose I and dose II, than in the placebo treated group (dose I and II both median of 1.0 compared to 1.7, p < 0.05). The adenomyosis severity index was reduced by 48% in the axitinib-treated groups (dose I p<0.05). In the placebo-treated group, the myometrium adjacent to the affected site (as a marker for hypertrophy) was thicker in the placebo- than in the axitinib-treated groups. There were no signs of fibrosis. MVD was reduced in myometrium of dose I treated mice by 14% compared with Ax25-treated mice (p<0.05), as well as compared to 6-week-old tamoxifen-treated mice (p<0.05). Expression of angiogenic growth factors and their receptors was markedly reduced in the dose I and II axitinib-treated groups compared to the placebo-treated group. Limitations, reasons for caution Limitations of this study include the uncertainty on the optimal timing to start treatment, and the assessment of the presence and severity of adenomyosis. Further research should focus on commonality among different angiostatic drugs, as well as the method and timing of application. Wider implications of the findings Since there is currently no treatment option for premenopausal women who wish to retain their uterus and their fertility, treatment with an angiogenesis inhibitor might provide a solution. The major requirement in further development of anti-angiogenesis therapy is a safety and side-effect profile tolerable for this population. Trial registration number Not applicable