Percentage of participants with objective response based assessment of confirmed complete response (CR) or confirmed partial response (PR). CR persisted on repeat imaging study at least (≥) 4 weeks after initial documentation of response. PR, for bidimensionally measurable disease, was a decrease by ≥50% of the sum of the products of the largest perpendicular diameters of all measurable lesions as determined by 2 observations not less than 4 weeks apart. Best overall response recorded any time while the participant was receiving treatment. External Response Review Committee (ERRC) assessment.

Primary Evaluable Population: subset of evaluable population predetermined by 2-stage Optimum Simon design. Medulloblastoma cohort: n=consecutive evaluable participants up to 46 if 6 responses obtained in first 15 evaluable participants. Glioma cohort: n=consecutive evaluable participants up to 29 if 1 response in first 10 evaluable participants.

Percentage of participants with objective response based assessment of confirmed CR or confirmed PR. CR persisted on repeat imaging study ≥4 weeks after initial documentation of response. PR, in case of bidimensionally measurable disease, was a decrease by ≥50% of the sum of the products of the largest perpendicular diameters of all measurable lesions as determined by 2 observations not less than 4 weeks apart. Best overall response could be recorded any time while the participant was receiving treatment. Investigator's assessment.

Evaluable local population: Participants received at least 1 dose of study medication, had measurable disease under study, at least 1 on-study objective tumor assessment, completed at least 2 cycles of study treatment or progressed. Based on investigator's assessment.

Median duration (50%) of tumor response for participants with objective disease response: who have not progressed or died due to any cause; with a response and subsequent progression or death due to any cause for duration of response (DR). DR was defined as time from start of first documented objective tumor response (CR or PR) to first documented objective tumor progression or death due to any cause, whichever occurred first. DR (calculated in Weeks) = (the end date for DR minus first subsequent confirmed CR or PR plus 1) divided by 7. Investigator's assessment.

Evaluable local population. Number of participants analyzed=number of participants who responded.

TTF was defined as the time from the date of first dose of study treatment to the date of the first documentation of progressive disease (PD), the date of treatment discontinuation except completion of treatment, or date of death due to cancer. Investigator's assessment.

Evaluable local population

TTP was defined as the time in months from start of study treatment to first documentation of objective tumor progression or death due to cancer, whichever came first. TTP was calculated as (first event date minus the date of first dose of study medication plus 1) divided by 7 multiplied by 4.33. Tumor progression was determined from oncologic assessment data (where data met the criteria for PD). Investigator's assessment.

Evaluable local population

Time in months from the start of study treatment to date of death due to any cause. OS was calculated as (the death date minus the date of first dose of study medication plus 1) divided by 7 multiplied by 4.33. Death was determined from adverse event data (where outcome was death) or from follow-up contact data (where the participant current status was death). Investigator's assessment.

All participants. One participant in the Temozolomide + Irinotecan for Medulloblastoma cohort did not have recurrent or refractory medulloblastoma and 3 participants in the Temozolomide + Irinotecan for High-Grade Glioma cohort did not have high-grade glioma, and were not considered evaluable for survival.