Efficacy Endpoints in Phase II Clinical Trials for Meningioma: An Analysis of Recent Clinical Trials

Background: Response Evaluation Criteria in Solid Tumors (RECIST)-based response rates are commonly used as efficacy endpoints in phase II clinical trials for solid tumors. However, no consensus has been reached concerning adequate efficacy endpoints for phase II clinical trials targeting meningioma. Irregularity of lesions after resection, and varying degrees of dysplasia and histologic subtypes make establishing an appropriate efficacy evaluation difficult.

Methods: We analyzed primary efficacy endpoints (PEEs) and background factors from 48 trials retrieved from ClinicalTrials.gov ( https://clinicaltrials.gov/ ) using the search criteria "meningioma," "interventional," "phase II," and "study start 4/1/2001 to 3/31/2021." Primary purpose of the study was efficacy endpoint setting in overall population and three subgroups.

Results: Among 45 PEEs set in the 39 trials included; 33 trials with single PEE, and six trials with double PEEs, 17/45 (38%) trials adopted progression-free survival (PFS) rate, 15/45 (33%) trials response rate (seven Macdonald criteria or modified, three RECIST, three volumetric estimation, one RANO criteria, one unknown), 10/45 (22%) PFS, 1/45 (2%) OS, and 2/45 (4%) other endpoints. Although 26 PEEs were time-to-event endpoints, 19 of the 26 PEEs were single-arm studies.

Conclusions: Time-to-event efficacy endpoints were often compared to historical data, and two-dimensional evaluation is more suitable than one-dimensional one. Accumulation of prognostic data is essential to standardize time-to-event efficacy endpoints. Considering the difficulty of setting design for phase II clinical studies targeting meningioma, evaluation might be done with multiple efficacy endpoints.