Patients must have received their last dose of known myelosuppressive anticancer chemotherapy at least three weeks prior to study registration or at least six weeks if nitrosoureaXx_NEWLINE_xXMyelosuppressive chemotherapy:* Subjects must have received their last dose of known myelosuppressive anticancer chemotherapy at least three (3) weeks prior to study registration or at least six (6) weeks if nitrosoureaXx_NEWLINE_xXChemotherapy: patients must have received their last dose of known myelosuppressive anticancer chemotherapy at least three (3) weeks prior to study enrollment in the study or at least six (6) weeks for those receiving nitrosoureaXx_NEWLINE_xXPatients must have received their last dose of known myelosuppressive anticancer therapy at least three (3) weeks prior to study enrollment or at least six (6) weeks if prior nitrosoureaXx_NEWLINE_xXINCLUSION CRITERIA FOR STRATUM C: Patients must have received their last dose of known myelosuppressive anticancer therapy at least three (3) weeks prior to study enrollment or at least six (6) weeks if prior nitrosoureaXx_NEWLINE_xXRECURRENT/ PROGRESSIVE DIPG (STRATUM 1): Patients must have received their last dose of known myelosuppressive anticancer therapy or immunotherapy at least 21 days prior to enrollment (42 days if prior nitrosourea)Xx_NEWLINE_xXMyelosuppressive chemotherapy: must not have received within 2 weeks of entry onto this studyXx_NEWLINE_xXPatients with solid tumors must not have received myelosuppressive chemotherapy within 3 weeks of enrollment onto this study (6 weeks if prior nitrosourea)Xx_NEWLINE_xX