Targeted, Dose-Escalation Busulfan-Etoposide as Prep Regimen
Condition: Acute Myeloid Leukemia
MeSH terms: Leukemia; Leukemia, Myeloid; Leukemia, Myeloid, Acute
Study type: Interventional
Phase: Phase 1

Summary: 
      Busulfan and etoposide have been used as preparative therapy for autoSCT (stem cell
      transplant) in adults with acute myeloid leukemia (AML) at UCSF for the past 10 years. Over
      this period and together with collaborative transplant centers, over 200 patients have
      received this treatment. By intent-to-treat analysis, and with median follow-up of 7.0 years,
      the 5-year DFS is 55%. The current protocol will utilize the combination of IV Busulfan (BU)
      and etoposide. The busulfan dose will be escalated amongst 3 targeted dose levels. All
      targeted dose levels represent higher busulfan dosing than standard myeloablative dosing,
      with the lowest dose being approximately 14% higher than standard. Busulfan levels will be
      monitored after the first, fourth and twelfth doses. Dose adjustments will be made "in real
      time" based on AUC levels determined from the first and fourth doses. This strategy of
      busulfan monitoring and dose adjustment has improved the therapeutic widow of BU in previous
      clinical trials.

      The current protocol will utilize the combination of intravenous busulfan and etoposide. The
      busulfan dose will be escalated amongst 3 targeted dose levels (area under the curve (AUC)
      levels at time 6 hours of 1250 uMol*min, 1400 uMol*min and 1550 uMol*min). All targeted dose
      levels represent higher busulfan dosing than standard myeloablative dosing with the lowest
      dose (1250 uMol*min) being approximately 14% higher than standard. In the absence of
      dose-limiting toxicity, cohorts of 4-6 patients will be treated at each dose level and 10
      additional patients will be treated at the maximum tolerated dose (MTD) to confirm safety.
      The busulfan dosing will begin at 1 mg/kg based on historical plasma levels obtained from
      patients receiving BU at a starting dose of 0.8 mg/kg at UCSF Medical Center.

      The highest dose level proposed for this study will exceed the reported toxic level for
      busulfan in the alloSCT setting. Patients will be followed closely for toxicity and strict
      stopping rules have been included. Eligibility criteria will exclude patients with prior
      history of hepatotoxicity or viral hepatitis. Potential hepatotoxic agents will not be
      allowed just prior to and during the busulfan dosing period. In addition, patients who
      experience hepatotoxicty during pre-transplant mobilization therapy may be excluded from
      receiving dose-escalated busulfan therapy. Every attempt will be made to prevent or avoid
      hepatotoxicity.
    

Detailed description: 
      TREATMENT: STEP 1 - CONSOLIDATION CHEMOTHERAPY

        -  Etoposide 10 mg/kg IV continuous infusion over 24 hrs for 4 days (total course dose 40
           mg/kg). Dose should be based on corrected weight, calculated as follows: Ideal + 25% of
           the difference between actual and ideal weight. If actual is less than ideal weight use
           actual weight. Etoposide infusion should be mixed in normal saline at a concentration of
           0.4-0.5 mg/ml. The infusion volume will be approximately 1.39 ml/kg/hour and should be
           rounded to the nearest 500-1000 ml and infused through a central venous catheter.

        -  Cytarabine (ara-C) 2,000 mg/m2 IV over 2 h q 12 h x 8 doses Days 1-4. Cytarabine dosage
           should be based on corrected weight, calculated as follows: Ideal weight + 25% of the
           difference between actual and ideal weight. If actual weight is less than ideal weight,
           use actual weight.Begin concurrent with etoposide infusion. Cytarabine doses should be
           mixed in 250 ml of D5W.

      To prevent neurotoxicity from high-dose cytarabine (HDAC), cytarabine doses will be adjusted
      according to renal function. The dose of cytarabine will be reduced to 1000 mg/m2/dose if
      creatinine is 1.5-1.9 mg/dL or if there is an increase from baseline creatinine at start of
      cytarabine of 0.6-1.1 mg/dL (example: baseline creatinine 0.8 mg/dL increase to 1.4 mg/dL
      (difference of 0.6 mg/dL)), decrease cytarabine to 1000 mg/m2/dose.The dose of cytarabine
      will be reduced to 100 mg/m2/dose if creatinine > 2.0 mg/dL or if there is an increase from
      baseline > 1.2 mg/dL.Cytarabine will be discontinued immediately for any clinical evidence of
      cerebellar neurotoxicity (dysarthria, dysmetria, gait disturbance).

      Supportive Care Measures:

        -  G-CSF 5 mcg/kg (actual body weight) SQ daily beginning day 14. The dose will be
           increased to 10 mcg/kg when WBC > 1000/uL is achieved. G-CSF 10 mcg/kg should then be
           continued until the peripheral blood stem cell collection has been completed. All G-CSF
           doses should be rounded up to a convenient dose based on vial sizes of 300 and 480mcg.

        -  Fluoromethalone 0.1% ophthalmic solution (or equivalent medication) 2 drops qid to each
           eye Days 1-6.

        -  Voriconazole 200 mg PO Q12 hours beginning the day after completion of chemotherapy (Day
           +6). Equivalent anti-fungal prophylaxis with itraconazole, posaconazole or
           Liposomal-based amphotericin (1mg/kg) may be used.

        -  Patients should be hospitalized in private rooms when possible.

        -  Strict low bacteria diet should be used when ANC < 500 cells/uL.

        -  Recommended mouth care:

           a. Salt and soda swish tid

        -  Transfusions: Institution standards should be followed for blood product support. In
           lieu of standards, packed RBCes should be given to maintain the hemoglobin >8.5 gm/dl or
           hematocrit >25%. Platelet should be transfused to keep the platelet count >10-20 x
           109/l. Blood should be filtered and irradiated (3000 cGy). CMV seronegative patients
           should receive CMV-seronegative blood products if available.

      PERIPHERAL BLOOD STEM CELL (PBSC) COLLECTION

        -  Begin collections when the total white blood count exceeds 10,000/µl or when appropriate
           based on peripheral CD34 cell counts (institutional standard)

        -  Aim for a total of 1-4 collections with a standard target CD34 cell dose of > 5 x 10 x
           106/kg and an optimal target CD34 cell dose of > 10 x 106/kg. The minimum CD34 cell dose
           is > 3 x 106/kg. Collections should continue until 10 x 106/kg CD34 (+) cell dose is
           achieved unless not clinically feasible.

        -  Stem Cell Collection: Process 18-20 L of whole blood over 3-4 hours according to
           institutional standards.

        -  PBSC Processing: The buffy coat is concentrated by centrifugation on Beckman centrifuge.
           Cells are suspended in Normasol media with 5% autologous plasma and 10% DMSO to a final
           cell concentration of 2.5 x 108/ml. Seventy ml aliquots are placed in polyolefin bags
           and frozen in a controlled rate freezer. Bags are labeled then stored in the liquid
           phase of a liquid nitrogen freezer. Institutional standard for PBSC processing should be
           followed.

        -  Four 2 ml aliquots of PBSC will be frozen in liquid nitrogen for future analysis.

      TREATMENT: STEP 2 - AUTOLOGOUS STEM CELL TRANSPLANT

        -  Mandatory Recovery Period: The patient may begin preparative therapy for stem cell
           transplant following a minimum of four weeks "out-of-hospital" time since discharge from
           consolidation/mobilization chemotherapy.

        -  Dose-Adjusted Busulfan

             1. Busulfan dose should be calculated using the corrected weight which equals ideal
                weight + 25% of the difference between actual and ideal weight. If the actual
                weight is less than ideal weight use actual weight.

             2. The initial dose of busulfan (Dose cohort #1 = 1 mg/kg, Dose cohort #2 = 1.2 mg/kg,
                Dose cohort # 3 = 1.4) will be given as a single intravenous dose on Day -10 (in
                the morning, at 9:00AM). The dose will be administered by intravenous injection
                over 2 hours in the Outpatient Ambulatory Care/Infusion Center.

                  1. The infusion tubing will be primed with busulfan diluted with saline to ensure
                     complete administration over 2 hours as detailed in Appendix 10.

                  2. The busulfan will be administered through a well functioning central venous
                     catheter. The busulfan infusion tubing should be connected directly to the
                     central venous catheter hub (i.e. directly to the catheter) to ensure busulfan
                     administration over two hours.

                  3. Busulfan levels will de drawn at 2, 3, 4 and 6 hours from the start of
                     Busulfan Dose #1. For Doses #4 and #12, levels will be drawn just prior to
                     infusion and at 2, 3, 4 and 6 hours, from a well functioning peripheral IV.
                     (SEE Appendix 9 for busulfan sampling)

        -  After the busulfan is administered on Day -10, and the serial serum samples have been
           obtained, the patient will be discharged from the ACC infusion center.

        -  Busulfan dosing will resume starting on day -8 and will be given IV q6h for an
           additional 15 doses (total 16 doses). Patients at UCSF will receive busulfan
           chemotherapy on the 11 Long Adult Inpatient Unit. Dose #2 will be administered at
           approximately 8 pm. This dose will be adjusted based on target dose level and PK data
           results following dose #1. The second dose will not be given until the PK data is
           available from dose #1.

        -  PK studies will also be performed following the 4th and 12th doses. The final busulfan
           dose-adjustment will be made at approximately dose #10 as determined by PK data. In some
           cases, the dose-adjustment may be delayed due to travel time or problems at the
           reference lab. No dose-adjustment will be made from data obtained from samplings made
           following the 12th dose.

        -  Dose adjustments will be based on a standard formula as recommended by the reference
           laboratory. Adjustments will be made to achieve the target AUC level from doses 2 until
           16. Dose adjustments will be calculated and confirmed by two physicians (including one
           of the co-PI's, if possible) at UCSF Medical Center.

      Dose adjustments and busulfan laboratory values will also be reviewed regularly by Jeanine
      McCune Ph D., at the University of Washington, in Seattle, WA. Dr. McCune is a collaborator
      on this trial and manages the Busulfan pharmacokinetics laboratory in Seattle. She is a
      leader in the field of Busulfan metabolism, pharmacokinetics and administration.
    

Intervention name(s): Busulfan
Intervention type(s): Drug
Intervention description(s): 1250 uMol*min (AUC to time 6 hrs)^
1400 uMol*min (AUC to time 6 hrs
1550 uMol*min (AUC to time 6 hrs)^
Intervention MeSH terms: Busulfan
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: AML; autologous transplant