Standard Maintenance POMP/D Plus Ixazomib Maintenance Therapy in Adult Patients With Acute Lymphoblastic Leukemia, Lymphoblastic Lymphoma or Mixed Phenotype Acute Leukemia in Complete Remission (CR)

PRIMARY OBJECTIVE

The primary objective is to determine the maximum-tolerated dose of IXAZOMIB (MLN9708)
(maximum of 4 mg, which is the recommended phase II dose for IXAZOMIB (MLN9708) in
combination with standard maintenance therapy with POMP/D (methotrexate, 6- mercaptopurine,
vincristine, prednisone/dexamethasone) and to assess the tolerability of POMP/D and IXAZOMIB
(MLN9708) maintenance in adult patients with acute lymphoblastic leukemia, lymphoblastic
lymphoma (LBL) or mixed phenotype acute leukemia (MPAL) in complete remission (CR).

SECONDARY OBJECTIVE

To determine the three-year progression-free survival (PFS) of patients treated with oral
IXAZOMIB (MLN9708) and standard maintenance regimen. Progression-free survival will be
measured from the start of induction to disease relapse.

STUDY DESIGN

The maximum-tolerated dose of single agent IXAZOMIB was 1.76 to 2.0mg/m2 when given on a
twice a week schedule1 and > 2.34 mg/m2 to 2.97 mg/m2 on a weekly schedule in previous
studies.

Three patients will be treated per dose level unless dose-limiting toxicity (DLT) is
observed. The starting dose of IXAZOMIB will be 3 mg orally on days 1, 8 and 15. If no DLT is
seen in the first three patients, the dose will be increased to 4 mg on days 1, 8 and 15 in a
classic 3 +3 phase I design. We will not attempt to increase the dose beyond 4 mg orally
which, if achieved with acceptable toxicity, would be accepted as the recommended phase 2
dose (RP2D). Zero of three DLTs would allow escalation to the next dose level. One of three
DLTs will require expanding to six patients; one of six DLTs will allow escalation again. Two
DLTs will require dose de-escalation. The maximum-tolerated dose (MTD) will be the highest
dose administered at which no more than one DLT was observed.

Inclusion criteria:

- Male or female patients 18 years or older.

- Have B-precursor, T cell ALL, MPAL or LBL in CR following therapy and receiving
maintenance therapy. Patients with persistent minimal residual disease and/or in
complete remission with incomplete platelet recovery are not eligible.

- Prior therapy: Should have achieved CR following the induction and intensification
phases of treatment, with no limit on the number of prior treatment regimens, and
started treatment with POMP/D maintenance. Patients who achieved CRp or CR with
persistence of minimal residual disease are not eligible.

- Patients are eligible after allogeneic stem cell transplantation.

- Eastern Cooperative Oncology Group (ECOG) performance status 0-2.

- Patients must meet the following clinical laboratory criteria:

- Total bilirubin < 1.5 X the upper limit of the normal range (ULN).

- Alanine aminotransferase (ALT) and aspartate aminotransferase. (AST) < 3 X ULN.

- Calculated creatinine clearance > 30 mL/min.

- Absolute neutrophil count (ANC) > 1,000/cmm and platelets > 75,000/cmm.

- Patient has a life expectancy of at least six months.

- Patients must be at least two weeks from major surgery, radiation therapy,
participation in other investigational trials and have recovered from clinically
significant toxicities of these prior treatments.

- Patients should be on stable doses of 6-mercaptopurine, methotrexate, vincristine and
prednisone/dexamethasone as part of the POMP/D regimen, for a minimum of eight weeks
PRIOR to starting ixazomib treatment.

- Patients should have at least six months of therapy with the POMP/D regimen remaining
prior to starting IXAZOMIB (MLN9708).

- Female patients who:

- Are postmenopausal for at least one year before the screening visit, OR

- Are surgically sterile, OR

- If they are of childbearing potential, agree to practice two effective. methods
of contraception, at the same time, from the time of signing the informed consent
form through 90 days after the last dose of study drug, AND

- Must also adhere to the guidelines of any treatment-specific pregnancy prevention
program, if applicable, OR

- Agree to practice true abstinence when this is in line with the preferred and
usual lifestyle of the subject. (Periodic abstinence [e.g., calendar, ovulation,
symptothermal, postovulation methods] and withdrawal are not acceptable methods
of contraception.)

- Male patients, even if surgically sterilized (i.e., status postvasectomy), must agree
to one of the following:

- Agree to practice effective barrier contraception during the entire study
treatment period and through 90 days after the last dose of study drug, OR

- Must also adhere to the guidelines of any treatment-specific pregnancy prevention
program, if applicable, OR

- Agree to practice true abstinence when this is in line with the preferred and
usual lifestyle of the subject. (Periodic abstinence (e.g., calendar, ovulation,
symptothermal, postovulation methods] and withdrawal are not acceptable methods
of contraception.)

Exclusion criteria:

- Systemic treatment, within 14 days before study enrollment, with strong CYP3A inducers
(rifampin, rifapentine, rifabutin, carbamazepine, phenytoin, phenobarbital), or use of
ginkgo biloba or St. John's wort.

- Uncontrolled intercurrent illness including, but not limited to ongoing or active
infection, symptomatic congestive heart failure, or psychiatric illness/social
situations that would limit compliance with study requirements. Patients should not
have evidence of active infection.

- Inability to swallow oral medication, inability or unwillingness to comply with the
drug administration requirements, or GI procedure that could interfere with the oral
absorption or tolerance of treatment.

- Active chronic graft vs. host disease requiring therapy.

- Patient has ≥ grade 2 peripheral neuropathy.

- Participation in clinical trials with other investigational agents not included in
this trial, within 14 days of the trial start and throughout the duration of this
trial.

- Failure to have fully recovered (i.e., < grade 1 toxicity) from the reversible effects
of prior chemotherapy.

- Evidence of current uncontrolled cardiovascular conditions, including uncontrolled
hypertension, uncontrolled cardiac arrhythmias, symptomatic congestive heart failure,
unstable angina, or myocardial infarction within the past six months.

- Any serious medical or psychiatric illness that could, in the investigator's opinion,
potentially interfere with treatment completion according to this protocol.

- Known allergy to any of the study medications, their analogues or excipients in the
various formulations of any agent.

- Diagnosed or treated for another malignancy within two years before study enrollment
or previously diagnosed with another malignancy and have any evidence of residual
disease. Patients with nonmelanoma skin cancer or carcinoma in situ of any type are
not excluded if they have undergone complete resection.

- Female patients who are breastfeeding or have a positive serum pregnancy test during
the screening.