Update on Systemic Therapies for Metastatic/Unresectable Pheochromocytomas and Paragangliomas and Future Directions

Metastatic or unresectable pheochromocytomas and paragangliomas (PPGLs) remain rare but clinically challenging neuroendocrine neoplasms with limited curative options. Traditionally managed with surgery, radionuclide therapy, or cytotoxic chemotherapy, systemic treatments have historically achieved disease stabilization, rather than durable remissions. In recent years, however, the therapeutic landscape has evolved substantially. Radiopharmaceuticals such as ¹³¹I-MIBG and ¹⁷⁷Lu-DOTATATE continue to play a pivotal role, achieving disease control in many patients. Cytotoxic regimens, particularly temozolomide, remain relevant, with some studies suggesting that SDHB-mutated PPGLs demonstrate a heightened sensitivity associated with MGMT promoter hypermethylation and reduced MGMT expression. Targeted agents are increasingly important: multi-kinase inhibitors such as sunitinib, anlotinib, and cabozantinib have shown meaningful activity. The landmark approval of belzutifan, a HIF-2α inhibitor, in 2025 represents the first oral targeted therapy for advanced/metastatic PPGL, which is particularly relevant for pseudohypoxic Cluster 1 tumors. Immunotherapy has yielded modest responses with checkpoint inhibitor monotherapy, but ongoing studies of dual checkpoint blockade and TKI-ICI combinations hold promise. Novel approaches, including PARP inhibition, metabolic targeting strategies, and cancer vaccines, are under investigation, especially for aggressive SDHB-related disease. Optimal sequencing of these therapies is emerging as a central challenge, with treatment strategies increasingly tailored to molecular genotype, tumor behavior, and functional imaging phenotype. This review summarizes current evidence and highlights ongoing clinical trials, underscoring a paradigm shift toward precision medicine and rational combination strategies. Collectively, these advances bring cautious optimism that metastatic PPGLs may soon become a more manageable chronic disease with improved survival and quality of life.