Study of Efficacy and Safety of Ribociclib (LEE011) in Combination With Topotecan and Temozolomide (TOTEM) in Pediatric Patients With Relapsed or Refractory Neuroblastoma and Other Solid Tumors

Inclusion Criteria:

1. Participants and/or guardian have the ability to understand and the willingness to
sign a written informed consent document.

2. Age ≥ 12 months and ≤ 21 years at the time of signing consent form Note: The first
dose level of Phase I - part A (dose finding) will enroll participants ≥ 12 years -
21 years old, and may expand to younger participants (≥ 12 months to < 12 years) as
determined by the data.

3. Histologically or cytologically confirmed solid tumors listed below that have
progressed despite standard therapy or for which no effective standard therapy
exists.

1. Neuroblastoma (for Phase I and Phase II): Histologically proven neuroblastoma
as per International Neuroblastoma Staging System (INSS); Relapsed or
refractory disease; Measurable disease per International Neuroblastoma Response
criteria (INRC); Bone marrow only disease not eligible; Available MYCN status
before screening

2. Medulloblastoma (for Phase I) regardless of genetic status (i.e. Groups 3 or 4
WNT-activated or non-WNT, SHH-activated or non-SHH)

3. High-grade glioma (for Phase I): including HGG NOS, WHO Grade III or Grade IV;
Glioblastoma, IDH-wildtype or IDH-mutant; Anaplastic astrocytoma, IDH-mutant;
Anaplastic oligodendroglioma, IDH-mutant; Anaplastic pleomorphic
xanthoastrocytoma; Diffuse midline gliomas, H3 K27-altered; Diffuse hemispheric
glioma, H3 G34-mutant; Diffuse pediatric-type HGG, H3-wildtype and
IDH-wildtype.

4. Malignant rhabdoid tumor (for Phase I) includes diagnoses of atypical
teratoid/rhabdoid tumor (AT/RT), and rhabdoid tumor of the kidney (RTK), and
other soft tissues as defined by 2 of the 3 following criteria; either (1)+(2)
or (1)+(3): (1) Morphology and immunophenotypic panel consistent with rhabdoid
tumor; (2) Loss of SMARCB1 confirmed by immunohistochemistry; (3) Molecular
confirmation of tumor-specific bi-allelic SMARCB1 loss/mutation is encouraged
in cases where SMARCB1 immunohistochemistry is equivocal, and required if
SMARCB1 immunohistochemistry is not available

5. Rhabdomyosarcoma (for Phase I) independent of fusion status and subtype

4. Participants with CNS disease who are on corticosteroids should take stable doses
for at least 7 days prior to first dose of ribociclib with no plans for escalation.

5. Performance status:

1. ≤ 16 years: Lansky Play score ≥ 50%

2. >16 years: Karnofsky performance status ≥ 50% or ECOG < 3

6. Life expectancy of ≥ 12 weeks at the time of enrollment

7. Adequate bone marrow function (bone marrow may be involved with tumor) and organ
function

8. Adequate hepatic, renal, cardiac function

9. Females who are sexually active must agree to use highly effective contraception
during and for 6 months after treatment. Additionally, females of childbearing
potential must have a negative serum pregnancy test within 7 days prior to the first
dose of study medication. Pregnant or lactating females are not eligible for the
study.

10. Sexually active males (including those that have had a vasectomy), who do not agree
to abstinence, must be willing to use a condom during intercourse while on study
treatment and for 6 months after stopping treatment.

Exclusion Criteria:

1. Known hypersensitivity to any of the excipients of ribociclib or topotecan or
temozolomide.

2. Not recovered from clinical and laboratory acute toxicities related to prior
anti-cancer therapies

3. Concurrent severe and/or uncontrolled concurrent medical conditions (serious
infections or significant cardiac, pulmonary, hepatic, psychiatric, GI disease, or
other organ dysfunction) that in the investigator's judgement could compromise their
ability to tolerate or absorb protocol therapy or would interfere with the study
procedures or results

4. Clinically significant, uncontrolled heart disease and/or cardiac repolarization
abnormality

5. History of QTc prolongation; taking medications with a known risk to prolong the QT
interval hat cannot be discontinued or replaced by safe alternative medication

6. Currently taking medications that are mainly metabolized by CYP3A4/5 with a narrow
therapeutic index, strong inducers or inhibitors of CYP3A4/5, herbal
preparations/medications and dietary supplements

7. Vaccinated with live, attenuated vaccines within 4 weeks

8. Participated in a prior investigational study within 30 days

9. Received prior treatment with a CDK4/6 inhibitor

10. Received last dose of anticancer therapy (including experimental) within 4 weeks

11. Previous myeloblative therapy with autologous hematopoietic stem cell rescue within
8 weeks

12. Allogeneic stem cell transplant within 3 months

13. Has last fraction of radiation within 4 weeks

14. Major surgery within 2 weeks

15. Pregnant or nursing (breast feeding) female participant or female participant who
plans to become pregnant or breast-feed during the trial.

Other protocol-defined inclusion/exclusion criteria may apply