Abemaciclib in Children With DIPG or Recurrent/Refractory Solid Tumors

Stratum A- Appropriate dose RT will be administered in 30-33 fractions over approximately 6
weeks for Stratum A patients. Treatment with abemaciclib (LY2835219) will start on the same
day as radiation therapy (RT) and continue twice daily during and after RT for a maximum
treatment duration of 2 years. Investigators plan to treat a maximum of 4 cohorts of research
participants (dosage levels 1, 2, 3, and 4) with escalating doses of abemaciclib (LY2835219)
starting with dose level 1 (80% of adult dose). A cycle is defined as 28 days and the first 6
weeks of therapy will constitute the dose-limiting toxicity (DLT)-evaluation period.
Participants must take abemaciclib by mouth as intact capsules.

Stratum B - Abemaciclib (LY2835219) will be administered orally on a twice daily basis
continuously for 28 days, which defines one cycle. The maximum treatment duration will be 2
years. Investigators plan to treat a maximum of 4 cohorts of research participants (dosage
levels 1, 2, 3, and 4) with escalating doses of abemaciclib starting with dose level 1 (80%
of adult dose). Dose escalation will be independent of Stratum A escalation. A cycle is
defined as 28 days and the first 4 weeks of therapy will constitute the DLT-evaluation
period. Participants must take abemaciclib by mouth as intact capsules.

Inclusion Criteria for All Participants:

- Patient must have measurable or evaluable disease.

- Age must be ≥ 2 years and < 25 years

- Body surface area (BSA) ≥ 0.5 m^2

- Lansky (for participants ≤ 16 years) or Karnofsky (for participants > 16 years)
performance score ≥ 40 at the time of study enrollment

- Adequate organ function at the time of study enrollment as follows:

- Bone marrow: Absolute neutrophil count (ANC) ≥ 1,000/μL, platelet count ≥
75,000/μL (transfusion independent for ≥ 7 days), hemoglobin concentration ≥
8g/dL (may be transfused)

- Patients with bone marrow metastatic disease who do not meet the above criteria
will be eligible to enroll in the study with the following count criteria. These
patients will not be evaluable for hematologic toxicity or hematologic DLT.

- ANC > 750/μL within 7 days prior to first dose of abemaciclib

- Platelet count > 50,000/μL (may receive platelet transfusions) within 7 days
prior to first dose of abemaciclib

- Hemoglobin ≥ 7.5 g/dL (may receive red blood cell (RBC) transfusions) within
7 days prior to first dose of abemaciclib

- Renal: Normal serum creatinine concentration based on age or glomerular
filtration rate (GFR) > 70 ml/min/1.73m^2

- Hepatic: Total bilirubin concentration < 1.5x the institutional upper limit of
normal for age; serum glutamic pyruvic transaminase (SGPT) < 10x the
institutional upper limit of normal for patients on Stratum A. Stratum B patients
must have SGPT < 4x the institutional upper limit of normal.

- Cardiac: Adequate cardiac conductivity with corrected Q-T interval (QTC) of < 450
ms on screening ECG.

- Female research participants of childbearing age must not be pregnant as confirmed by
a serum or urine pregnancy test within 1 week of start of treatment. Participants must
not be breast-feeding.

- All patients should submit an archival tumor biopsy specimen (collected at diagnosis
or relapse). Patients who have no tumor tissue available may be permitted to
participate after discussion with the principal investigator.

- Males or females of reproductive potential may not participate unless they have agreed
to use two effective contraceptive methods. Abstinence in a non-sexually active child
will be sufficient birth control.

Inclusion Criteria for Stratum A (Newly Diagnosed DIPG)

- Diagnosis of DIPG or high-grade glioma originating from the brainstem

- Participants have had no previous treatment except corticosteroid use.

Inclusion Criteria for Stratum B (Recurrent/refractory/progressive MBT (including DIPG) or
ST)

- Patients must have radiologic evidence of recurrent, refractory or progressive
malignant central nervous system (WHO Grade III or IV) or solid tumor. For patients
with radiologic features of DIPG histologic confirmation of diagnosis is not required
though biopsy is suggested if clinically indicated.

- Patients with neurological deficits should have deficits that are stable for a minimum
of 1 week prior to registration.

- Patients who are on dexamethasone must be on a stable or decreasing dose for at least
one week prior to registration.

- Patients must have fully recovered from the acute toxic effects of chemotherapy,
immunotherapy, or radiotherapy prior to entering this study.

- Myelosuppressive chemotherapy: Patients must have received their last dose of known
myelosuppressive anticancer chemotherapy at least 21 days prior to study registration
or at least six weeks if nitrosourea. At least two weeks must have lapsed if patients
received lower dose oral etoposide (50 mg/2) without experiencing evidence of
myelosuppression (i.e. neutropenia or requiring transfusion with blood products)

- Biologic agent: Patient must have recovered from any toxicity potentially related to
the agent and received their last dose of the biologic agent ≥ 7 days prior to study
registration.

- Monoclonal antibody treatment: At least three half-lives must have elapsed prior to
registration.

- Radiation: Patient has received radiation therapy prior to study registration.
Patients must have had their last fraction of local irradiation to the primary tumor ≥
3 months prior to registration, their last fraction of craniospinal irradiation
(>24Gy) or total body irradiation > 3 months prior to registration or > 6 wks for
therapeutic doses of metaiodobenzylguanidine (MIBG). Patient has not received focal
irradiation for symptomatic metastatic sites within 14 days prior to registration.

- Bone Marrow Transplant: Patient must be ≥ 3 months since high dose chemotherapy and
peripheral blood stem cell rescue prior to registration.

- Autologous stem cell transplant following myeloablative therapy within 3 months prior
to the first dose of abemaciclib or prior allogeneic stem cell transplant at any time.
Patients who received stem cell reinfusion following non-myeloablative therapy are
eligible once they meet peripheral blood count criteria.

- Growth factors: Patients must be off all colony forming growth factors(s) for at least
1 week prior to registration (filgrastim, sargramostim, erythropoietin) and at least 2
weeks for long-acting formulations (e.g. Neulasta).

Exclusion Criteria:

- Patients with uncontrolled infection

- Patients with any concomitant significant medical illness that in the investigator's
opinion cannot be adequately controlled with appropriate therapy, or that would impair
the evaluation of side effects related to this treatment, alter drug metabolism or the
tolerance to this treatment

- Patients receiving any other anticancer or investigational drug therapy

- Prior therapy with abemaciclib

- Known mutation of Rb in tumor tissue

- Prior history of QTC prolongation or QTC>450 ms on screening ECG.