Propranolol monotherapy in angiosarcoma - A window-of-opportunity study (PropAngio)

Background: Angiosarcoma is a rare and aggressive cancer of the endothelial cells. Propranolol, a non-selective beta-blocker, was able to initiate apoptosis in angiosarcoma cell lines and its anti-tumor activity has been described in several case reports. The aim of this trial was to prospectively evaluate the anti-tumor activity of propranolol monotherapy in patients with angiosarcoma before proceeding to standard of care treatment. Methods: Propranolol was dosed 80 mg to 240 mg/day for 3 to 6 weeks according to a dose titration schedule. The primary endpoint was clinical response (response according to RECIST 1.1 or stable disease with improvement of cutaneous lesions) in at least three patients. Exploratory objectives included histologic response (>30% decrease in Ki-67), FDG PET response, and beta-receptor expression levels. Results: Fourteen patients were enrolled. The median duration of treatment was 26 days (range 21-42 days). The median highest propranolol dose was 160 mg/day (range 80 - 240 mg). Two patients showed clinical response (14%, 95% CI 3-100%). One of these patients showed a partial metabolic response on PET-CT. None of the tumors showed histologic response. The most common adverse event was grade 1/2 bradycardia (86%). There were no grade >= 3 adverse events. ADRB2 was overexpressed in 16 out of 18 tumors, in both responders and nonresponders. None of the tumors showed ADRB1 overexpression. Conclusions: This window-of-opportunity trial did not show clinical efficacy of propranolol monotherapy. However, two out of 14 patients did show clinical benefit. ADRB1/2 expression did not correlate with clinical response.