Subject characteristics
In Stratum I, a total of 21 patients were enrolled. A total of 28 patients were pre-screened with 22 Rb-positive, 5 Rb-negative, and 1 with inadequate tissue. Of the 22 patients with Rb-positive tumors, 14 elected to enroll for treatment. The remaining 7 patients had DIPG and did not require Rb testing (Table 1 ). For Stratum II, 14 patients were enrolled. A total of 15 patients were pre-screened with 12 Rb-positive and 3 Rb-negative. Of the 12 patients with Rb-positive tumors, 9 elected to enroll for treatment. The remaining 5 patients had DIPG or medulloblastoma and did not require Rb testing (Table 1 ). The most common tumor type was DIPG for stratum I (7/21 patients) and ependymoma for stratum II (7/14 patients). There was a male predominance in Stratum II (Table 1 ).