Efficacy of chemotherapy and targeted therapy for metastatic pheochromocytoma / paraganglioma: retrospective analysis

Introduction : Pheochromocytoma (PC) and paraganglioma (PG) are rare neuroendocrine tumors derived from adrenal chromaffin cells. The main options of systemic therapy for PC / PG are alkylating agent-based chemotherapy (ChT) and targeted therapy with sunitinib. There are no comparative data on the efficacy of these options, which became the purpose of this study. Materials and methods : This retrospective single-center study included patients over 18 y. o. who received ChT or targeted therapy for the first line treatment for metastatic PC / PG from September 2015 to August 2023. Results: The study included 33 patients (pts) who were divided into two groups — ChT (N = 18, 54.5 %) and targeted therapy (N = 15, 45.5%). In the ChT group, 12 pts (66.7%) received CVD regimen, 6 (33.3%) — temozolomide. In the targeted therapy group, 10 pts (66.7%) received sunitinib, 4 (26.7%) — pazopanib, and 1 (6.7%) — everolimus. Concurrent somatostatin analogues therapy was prescribed in 12 (66.7%) and 10 (66.7%) pts in the ChT and targeted therapy groups, respectively. Both groups were comparable by all main characteristics. Objective response was achieved in 11.11 % (N = 2) and 6.67 % (N = 1) [p=0.99], disease control > 6 months — 61.11 % and 60% (p = 0.99), biochemical response — 36.36% and 30% (p = 0.9) in the ChT and targeted therapy groups, respectively. Median PFS was 12.7 (2.9-22.3) in the ChT versus 12.9 months (2.3-26.5) in the targeted therapy group (p = 0.55). Median overall survival was not reached in both groups. Discussion : According to comparable efficacy of both treatment options and the indolent course of PC / PG, most patients do not require ChT in the 1st line of treatment. While choosing the 1st line therapy it is necessary firstly to take into account the safety profile of the drugs.