Inclusion Criteria:

        Participants must be < 22 years of age.

        Diagnosis:

        Participants must have a diagnosis of acute lymphoblastic leukemia and disease meets at
        least one of the following criteria:

          -  relapsed or refractory to chemotherapy as defined by ≥5% leukemic blasts in the bone
             marrow or flow cytometry confirmed leukemic blasts in the peripheral blood

          -  relapsed after hematopoietic stem cell transplantation (HSCT)

        Patients must have had histologic, morphologic or flow cytometric verification of the
        malignancy at relapse.

        Performance Level:

        Karnofsky or Lansky performance score is ≥ 50% (corresponding to ECOG Score of ≤ 2). The
        Lansky performance score should be used for participants < 16 years and the Karnofsky
        performance score for participants ≥ 16 years. Patients who are unable to walk because of
        paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of
        assessing the performance score.

        Prior Therapy:

        Patients who relapse while receiving standard ALL maintenance chemotherapy will not be
        required to have a waiting period before entry onto this study.

        Patients who relapse on therapy other than standard ALL maintenance must have fully
        recovered from the acute toxic effects of all prior anti-cancer therapy, defined as
        resolution of all such toxicities to ≤ Grade 2 or lower per the inclusion/exclusion
        criteria prior to entering this study.

        At least 14 days must have elapsed since the completion of cytotoxic therapy, with the
        exception of standard maintenance therapy and steroids.

        At least 7 days must have elapsed since completion of therapy with a biologic agent. For
        agents that have known adverse events occurring beyond 7 days after administration, this
        period prior to enrollment must be extended beyond the time during which adverse events are
        known to occur.

        At least 3 half-lives must have elapsed since prior therapy that included a monoclonal
        antibody with the exception of blinatumomab. Patients must have been off blinatumomab
        infusion for at least 7 days and all drug related toxicity must have resolved to grade 2 or
        lower as outlined in the inclusion/exclusion criteria.

        At least 42 days must have elapsed since CAR-T cell therapy.

        At least 90 days have elapsed since bone marrow transplant and participant is off immune
        suppression for ≥ 2 weeks, if applicable with no evidence of active GVHD.

        At least 2 weeks must have elapsed since local XRT (small port); ≥ 3 months must have
        elapsed if prior cranial or craniospinal XRT was received, if ≥ 50% of the pelvis was
        irradiated, or if TBI was received; ≥ 6 weeks must have elapsed if other substantial bone
        marrow irradiation was given.

        Organ Function Requirements:

        Adequate renal function defined as glomerular filtration rate ≥ 60 cc/min/1.73m2 or serum
        creatinine based on age as follows:

          -  Age: <6 months; maximum serum creatinine (mg/dL): 0.4 (male, female); Age: 6 months to
             <1 year; maximum serum creatinine (mg/dL): 0.5 (male, female); Age: 1 to < 2 years;
             maximum serum creatinine (mg/dL): 0.6 (male, female); Age: 2 to < 6 years; maximum
             serum creatinine (mg/dL): 0.8 (male, female); Age: 6 to <10 years; maximum serum
             creatinine (mg/dL): 1 (male, female); Age: 10 to <13 years; maximum serum creatinine
             (mg/dL): 1.2 (male, female); Age: 13 to <16 years; maximum serum creatinine (mg/dL):
             1.5 (male), 1.4 (female); Age: ≥ 16 years; maximum serum creatinine (mg/dL): 1.7
             (male), 1.4 (female)

        Adequate hepatic function defined as:

          -  Total bilirubin ≤ 2 x upper limit of normal (ULN) for age, and

          -  ALT ≤ 3 x ULN for age, unless elevation is due to leukemic infiltration.

        Adequate cardiac function defined as shortening fraction of ≥ 27% or ejection fraction ≥
        45%.

        Adequate pulmonary function defined as:

          -  No evidence of dyspnea at rest, no exercise intolerance, and a pulse oximetry > 94%.

          -  No evidence of acute pulmonary infiltrates on chest radiograph.

        Adequate central nervous system (CNS) function defined as:

          -  Patients with seizure disorder may be enrolled if on allowed anti-convulsants and well
             controlled. Benzodiazepines and gabapentin are acceptable.

          -  CNS toxicity < Grade 2

        Adequate peripheral nervous system (PNS) function defined as:

          -  PNS toxicity < Grade 2.

        Exclusion Criteria:

        Extramedullary disease status: patients with isolated CNS disease or isolated testicular
        disease are not eligible.

        Concurrent chemotherapy or targeted anti-cancer agents, other than intrathecal therapy.

        Patients who have previously received bortezomib or other proteasome inhibitors that did
        not have a response while receiving the inhibitor are not eligible. Patients that responded
        but had a subsequent relapse are eligible.

        Patients who have previously received palbociclib or other CDK4/6 inhibitors are not
        eligible.

        Patient with concurrent severe and/or uncontrolled medical conditions that, in the opinion
        of the investigator, may impair participation in the study or the evaluation of safety
        and/or efficacy.

        Patients that have an active, uncontrolled infection are not eligible.

        Known HIV infection or active hepatitis B (defined as hepatitis B surface antigen-positive)
        or C (defined as hepatitis C antibody-positive).

        Pregnant or lactating (female participant of childbearing potential must have negative
        serum or urine pregnancy test required within 7 days prior to start of treatment).

        Male or female participant of reproductive potential must agree to use appropriate methods
        of contraception for the duration of study treatment and for at least 30 days after last
        dose of protocol treatment.

        Cumulative anthracyclines must not exceed 450mg/m2 doxorubicin equivalents following
        completion of treatment on protocol. Therefore for patients receiving one course on
        protocol cumulative anthracyclines must be less than or equal to 400mg/m2 doxorubicin
        equivalents at the time of enrollment

        Inability or unwillingness or research participant or legal guardian/representative to give
        written informed consent.