Patients with histologically or radiologically confirmed MPP were enrolled. TMZ was administered orally at an initial daily dose of 150 mg/m2 per day for 5 days, every 28 days. In patients with a good tolerance during the first cycle, the dose was increased to 200 mg/m2 per day for 5 days, every 28 days. Plasma normetanephrine and metanephrine (MNs), 24-hour urinary catecholamine excretion (24hCA) and neuron specific enolase (NSE) were measured at baseline and every 1-3 cycle. Contrast-enhanced computed tomography（CT ）of chest, abdomen and pelvis were used to assess measurable target lesions at baseline and every 3 cycles. For patients who only had bone metastases or no measurable target lesions, TMZ efficacy was evaluated by 18F-fluorodeoxyglucose (18F-FDG-PET/CT). The primary endpoint was objective response rate (ORR) per Response Evaluation Criteria In Solid Tumors（RECIST) 1.1/PERCIST1.0. Secondary endpoints included biochemical (catecholamine levels) response rate (BRR), progression-free survival (PFS) and safety. The investigators will try to explore which patients are more suitable for TMZ treatment.
Metastatic pheochromocytoma / paraganglioma (MPP) are rare while the prognosis was poor. Temozolomide (TMZ) is a novel oral alkylation chemotherapeutic agent. TMZ has been recommended in National Comprehensive Cancer Network (NCCN) Guidelines Version 1.2019 for treating MPP patients.However, studies investigating TMZ efficacy in MPP patients are extremely limited. The largest study involved only 15 patients till date. The safety and efficacy of TMZ treatment in MPP patients need to be verified in larger studies.