A novel strategy for predicting the efficacy of temozolomide treatment for metastatic pheochromocytomas/paragangliomas.

Abstract

There are few studies on the efficacy of temozolomide (TMZ) in the treatment of Metastatic pheochromocytoma / paraganglioma (MPP) patients. And it remains unclear which MPP patients may benefit from TMZ treatment. This wasa prospective study. MPP patients were enrolled. Patients were treated with TMZ until disease progression or intolerable toxicities. The primary endpoints were disease control rate (DCR) and objective response rate (ORR). Secondary endpoints included biochemical response rate progression-free survival (PFS) and safety. Wecomparedthe difference between effective and ineffective groups, to explore which patients are more suitable for TMZ treatment. 62 patients with MPP were enrolled and tumor response were evaluated in 54 patients. The DCR was 83% (35/42), and the ORR was 24% (10/41) among the progressive patients. PFSwas 25.2 ± 3.1months. The most common adverse event was nausea(41/55). We found that 92.9% (13/14) of patients with MGMT methylation greater than 7% respond to treatment. For the patients with MGMT methylationless than 7%, Ki-67 index could be used to guide the use of TMZ in these patients. Among the patients with Ki-67 index less than 5%, 66% (8/12) patients showed respond to treatment, and only 33% (4/12) patients with Ki-67 index more than 5% showed respond to TMZ. This study indicated that TMZis a potential choice for the treatment of MPP with the high ability on disease control and well tolerability. Werecommended to MGMT methylation analysis testandKi-67 index to guideTMZ application.