Absolute neutrophil count (ANC) >= 1,500/mm^3 , equivalent to Common Toxicity Criteria (Common Terminology Criteria for Adverse Events [CTCAE] version [v] 3.0) grade 1Xx_NEWLINE_xXAbsolute neutrophil count (ANC) greater than or equal to 1,500/mcl, equivalent to Common Terminology Criteria for Adverse Events (CTCAE) grade 1Xx_NEWLINE_xXGrade 3-4 electrolyte abnormalities (Common Terminology Criteria for Adverse Events [CTCAE], version [v.] 4):Xx_NEWLINE_xXThe participant has not recovered to baseline or Common Terminology Criteria for Adverse Events (CTCAE) =< grade 1 from toxicity due to all prior therapies except alopecia and other non-clinically significant adverse events (AEs)Xx_NEWLINE_xXThe subject has not recovered to baseline or Common Terminology Criteria for Adverse Events (CTCAE) =< grade 1 from related toxicity to all prior therapies except alopecia and other non-clinically significant adverse events (AEs)Xx_NEWLINE_xXPatients must have recovered to =< grade 1 Common Terminology Criteria for Adverse Events (CTCAE) version (v) 4 from toxicity of prior chemotherapy or biologic therapy and must not have had prior chemotherapy or biologic therapy within 4 weeks (6 weeks for nitrosoureas or mitomycin C, 8 weeks for 7-hydroxystaurosporine [UCN-01])Xx_NEWLINE_xXSubjects must have recovered from the acute toxicities of all prior therapy before entering this study; for those acute baseline adverse events attributable to prior therapy, recovery is defined as a toxicity grade =< 2, using Common Terminology Criteria for Adverse Events (CTCAE) version (v.) 4.0, unless otherwise specified in the inclusion and exclusion criteriaXx_NEWLINE_xXAll prior treatment-related toxicities must be Common Terminology Criteria for Adverse Events (CTCAE) version (v)4 grade =< 1 (except alopecia) at the time of randomizationXx_NEWLINE_xXPrevious intolerance to BCG intravesical therapy suggested by development of systemic BCG infection in the past and/or grade 4 or greater adverse effect by Common Terminology Criteria for Adverse Events (CTCAE) version (v) 5.0Xx_NEWLINE_xXAll prior treatment-related toxicities must be Common Terminology Criteria for Adverse Events version 5.04 (CTCAE v5.04) grade =< 1 (except alopecia) at the time of enrollmentXx_NEWLINE_xXAll prior treatment-related toxicities must be Common Terminology Criteria for Adverse Events version 4 (CTCAE v 4) grade =< 1 (except alopecia) at the time of enrollment; this requirement to return to =< grade 1 does not apply to immune checkpoint inhibitor related endocrinopathies (e.g. thyroiditis, hypophysitis, etc.) that necessitate hormone replacement therapy including, but not limited to levothyroxine, cortisol, and testosterone; CTCAE v5.0 will be utilized beginning April 1, 2018Xx_NEWLINE_xXNervous system disorders (Common Terminology Criteria for Adverse Events version 4 [CTCAE v4]) resulting from prior therapy must be =< grade 2Xx_NEWLINE_xXPersistent toxicities (>= Common Terminology Criteria for Adverse Events [CTCAE] grade 2) caused by previous cancer therapy, excluding alopecia and CTCAE grade 2 peripheral neuropathyXx_NEWLINE_xXAll prior treatment-related toxicities must be Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v 4.0) grade =< 1 (except alopecia); grade 2 prior treatment related toxicities may be allowed after discussion with the principal investigatorXx_NEWLINE_xXAny valve disease Common Terminology Criteria for Adverse Events (CTCAE) gradeXx_NEWLINE_xXPatients with active >= Common Terminology Criteria for Adverse Events (CTCAE) version (v.) 4 grade 2 neuropathy are ineligibleXx_NEWLINE_xXThe subject has not recovered to baseline or Common Terminology Criteria for Adverse Events (CTCAE) =< grade 1 from toxicity due to all prior therapies except alopecia and other non-clinically significant adverse events (AEs)Xx_NEWLINE_xXThe subject has not recovered to baseline or Common Terminology Criteria for Adverse Events (CTCAE) =< grade 1 from toxicity due to all prior therapies except alopecia and other non-clinically significant adverse events (AEs) defined as lab elevation with no associated symptoms or sequelaeXx_NEWLINE_xXAll prior treatment-related toxicities must be Common Terminology Criteria for Adverse Events (CTCAE) version (V) 5 grade =< 1 (except alopecia); certain exceptions apply, such as immunotherapy-induced hypothyroidism or adrenal insufficiency or panhypopituitarism requiring stable doses of hormone replacement or rash from prior therapyXx_NEWLINE_xXThe participant has not recovered to baseline or Common Terminology Criteria for Adverse Events (CTCAE) =< grade 1 from toxicity due to all prior therapies except =< grade 2 alopecia, neuropathy, and other non-clinically significant adverse events (AEs)Xx_NEWLINE_xXRECURRENT/ PROGRESSIVE DIPG (STRATUM 1): Patients have diarrhea > Common Terminology Criteria for Adverse Events (CTCAE) grade 2Xx_NEWLINE_xXPRIOR/CONCURRENT THERAPY CRITERIA: Patients must not have received any chemotherapy, biologic agent, or any investigational agent within 14 days prior to registration. Patients must have recovered from any adverse events to Common Terminology Criteria for Adverse Events (CTCAE) grade 0-1 prior to registrationXx_NEWLINE_xXActive, clinically serious infections > Common Terminology Criteria for Adverse Events (CTCAE) grade 2Xx_NEWLINE_xXNervous system disorders (Common Terminology Criteria for Adverse Events [CTCAE] version [v]4) resulting from prior therapy must be =< grade 2Xx_NEWLINE_xXPatients may have received prior surgery; all adverse events associated with prior surgery must have resolved to =< grade 1 (per Common Terminology Criteria for Adverse Events [CTCAE] 4.0) prior to registrationXx_NEWLINE_xXPatients who received prior medical therapy for a NF1 related tumor must have recovered from the acute toxic effects of all prior therapy to =< grade 1 Common Terminology Criteria for Adverse Events (CTCAE) version (v) 5 before entering this studyXx_NEWLINE_xXRecovered from adverse events to grade 1 or less toxicity according to Common Terminology Criteria for Adverse Events version 4.0 (CTCAE 4.0) due to agents administered previously* NOTE: Chemotherapy-induced alopecia and grade 2 neuropathy are acceptableXx_NEWLINE_xXPatients who have not recovered from adverse events due to prior anti-cancer therapy (i.e., have residual toxicities > Common Terminology Criteria for Adverse Events [CTCAE] grade 1 or baseline, with the exception of alopecia)Xx_NEWLINE_xXNervous system disorders (National Cancer Institute Common Terminology Criteria for Adverse Events [NCI CTCAE] version 5.0) resulting from prior therapy must be =< grade 2 with the exception of decreased tendon reflex (DTR); any grade of DTR is eligibleXx_NEWLINE_xXAny unresolved toxicities from prior therapy greater than Common Terminology Criteria for Adverse Events (CTCAE) grade 1 at the time of starting study treatment with the exception of alopecia and grade 2 platinum-therapy related neuropathyXx_NEWLINE_xXPatients with peripheral neuropathy >= Common Terminology Criteria for Adverse Events (CTCAE) grade 2 are ineligibleXx_NEWLINE_xXPatients who have not recovered to < Common Terminology Criteria for Adverse Events (CTCAE) grade 2 toxicities related to prior therapy are ineligibleXx_NEWLINE_xXAll prior treatment-related toxicities must be Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v5) grade =< 1 (except alopecia) at the time of enrollmentXx_NEWLINE_xXNervous system disorders (Common Terminology Criteria for Adverse Events [CTCAE] version [V] 4.0) resulting from prior therapy must be =< grade 2Xx_NEWLINE_xXNervous system disorders (by Common Terminology Criteria for Adverse Events version 5.0 [CTCAE V 5.0]) resulting from prior therapy must be =< grade 2, with the exception of decreased tendon reflex (DTR); any grade of DTR is eligibleXx_NEWLINE_xX