Study Protocol of a Prospective, Monocentric, Single-Arm Study Investigating the Safety and Efficacy of Local Ablation of Symptomatic Uterine Fibroids with US-Guided High-Intensity Focused Ultrasound (HIFU)

Uterine fibroids are the most common benign tumors of the uterus. Approximately 20-50% of women with myomas experience a variety of symptoms such as vaginal bleeding, abdominal pain, pelvic pain and pressure, and urological problems, possibly interfering with fertility and pregnancy. Although surgery remains the standard treatment option for fibroids, non-invasive therapeutic options, such as high-intensity focused ultrasound (HIFU), have emerged over the last dec ade. During HIFU, ultrasound is focused on the target tissue causing coagulation necrosis. HIFU has, meanwhile, become an established method for treating uterine fibroids in many countries. Clinical data have shown that it effectively alleviates fibroid-related symptoms and reduces fibroid size with a very low rate of side effects. However, there is a lack of data on how this treatment affects laboratory parameters and structural features of uterine tissue. As our center is the only one in German-speaking countries where ultrasound-guided HIFU technology is currently established, the aim of this prospective, monocentric, single-arm trial is not only to evaluate the safety and efficacy of local US-guided HIFU in symptomatic uterine fibroid patients according to GCP standards but also to explore its effects on blood parameters and the structural integrity of uterine tissue using elastographic methods.

Succinate Mediates Tumorigenic Effects via Succinate Receptor 1: Potential for New Targeted Treatment Strategies in Succinate Dehydrogenase Deficient Paragangliomas

Paragangliomas and pheochromocytomas (PPGLs) are chromaffin tumors associated with severe catecholamine-induced morbidities. Surgical removal is often curative. However, complete resection may not be an option for patients with succinate dehydrogenase subunit A-D (SDHx) mutations. SDHx mutations are associated with a high risk for multiple recurrent, and metastatic PPGLs. Treatment options in these cases are limited and prognosis is dismal once metastases are present. Identification of new therapeutic targets and candidate drugs is thus urgently needed. Previously, we showed elevated expression of succinate receptor 1 (SUCNR1) in SDHB PPGLs and SDHD head and neck paragangliomas. Its ligand succinate has been reported to accumulate due to SDHx mutations. We thus hypothesize that autocrine stimulation of SUCNR1 plays a role in the pathogenesis of SDHx mutation-derived PPGLs. We confirmed elevated SUCNR1 expression in SDHx PPGLs and after SDHB knockout in progenitor cells derived from a human pheochromocytoma (hPheo1). Succinate significantly increased viability of SUCNR1-transfected PC12 and ERK pathway signaling compared to control cells. Candidate SUCNR1 inhibitors successfully reversed proliferative effects of succinate. Our data reveal an unrecognized oncometabolic function of succinate in SDHx PPGLs, providing a growth advantage via SUCNR1.