NovoTTF Therapy is a novel and US Food and Drug Administration (FDA)-approved antimitotic treatment for recurrent GBM with potential benefits compared with other options. Recurrent GBM patients from two prior trials with demonstrated radiologic tumor response to single-agent NovoTTF Therapy were analyzed to better characterize tumor response patterns and evaluate the associations between response, compliance, and OS. In addition, a compartmental tumor growth model was developed and evaluated for its ability to predict GBM response to tumor-treating fields (TTFields). The overall response rate across both trials was 15% (4% complete responses): 14% in the phase III trial (14/120) and 20% (2/10) in a pilot study. Tumor responses to NovoTTF Therapy developed slowly (median time to response, 5.2 months) but were durable (median duration, 12.9 months).