alvocidib and Precursor-Cell-Lymphoblastic-Leukemia-Lymphoma

The serine/threonine kinase inhibitor flavopiridol targets multiple cyclin-dependent kinases, induces checkpoint arrest, and interrupts transcriptional elongation. We designed a phase I clinical trial using a timed sequential therapy approach where flavopiridol was given for the dual purpose of initial cytoreduction and enhancing cell cycle progression of the remaining leukemia cell cohort followed by cycle-dependent drugs 1-beta-D-arabinofuranosylcytosine (ara-C) and mitoxantrone.. Flavopiridol was given by 1-hour infusion daily for 3 days beginning day 1 followed by 2 g/m2/72 h ara-C beginning day 6 and 40 mg/m2 mitoxantrone beginning day 9. In vivo correlates included pharmacokinetics, modulation of blast cycle regulators, and serum and marrow supernatant vascular endothelial growth factor levels.. Of 34 adults receiving induction therapy, 16 (47%) evinced direct leukemia cytotoxicity with > or =50% drop in peripheral blast counts and tumor lysis in 9 (26%). Four (12%) died during therapy (two fungal infections and two sudden death). Dose-limiting toxicity occurred at 60 mg/m2/d with profound neutropenia >40 days duration, and maximal tolerated dose was 50 mg/m2/d. Overall response rate was 31% in 26 acute myelogenous leukemia and 12.5% in acute lymphoblastic leukemia. Pharmacokinetics showed that a linear two-compartment model with first-order elimination provided the best fit of the observed concentration versus time data. Flavopiridol down-regulated one or more target proteins in marrow blasts in vivo. Vascular endothelial growth factor was detected in sera and marrow supernatant pretreatment, and sera obtained on day 3 inhibited bovine aortic endothelial cell proliferation by a mean of 32% (range, 10-80%).. Our data suggest that flavopiridol is cytotoxic to leukemic cells and, when followed by ara-C and mitoxantrone, exerts biological and clinical effects in patients with relapsed and refractory acute leukemias. These findings warrant continuing development of flavopiridol at 50 mg/m2/d x 3 days in combination with cytotoxic and biological agents for acute leukemias.

Topics: Adult; Aged; Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Bone Marrow Cells; Cattle; Cell Proliferation; Cohort Studies; Cytarabine; Endothelium, Vascular; Female; Flavonoids; Humans; Leukemia, Myeloid, Acute; Male; Maximum Tolerated Dose; Middle Aged; Mitoxantrone; Neoplasm Recurrence, Local; Piperidines; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Salvage Therapy; U937 Cells; Vascular Endothelial Growth Factor A

Topics: Apigenin; Cell Cycle Checkpoints; Cell Death; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Humans; Molecular Docking Simulation; Molecular Structure; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Structure-Activity Relationship

New agents are needed for treatment of children with relapsed acute lymphoblastic leukemia (ALL). Based on altered expression of cell cycle regulatory proteins, including frequent p16 (INK4A) and p15 (INK4B) deletions, flavopiridol (FP; Alvocidib) is an attractive agent for relapsed ALL.. We evaluated the efficacy of FP in ALL cell lines using cell proliferation assays, determined the effects of FP treatment on cell growth and viability in cell lines and patient samples, examined cell cycle kinetics, and evaluated the effect of FP on endogenous cyclin-dependent kinase (CDK) activity, Mcl-1 expression, and RNA polymerase II expression and phosphorylation.. ALL cell lines are sensitive to FP. At lower concentrations, FP induces transient G(1)-S cell cycle arrest and modest levels of apoptosis in cell lines. In contrast, a sustained G(1)-S and G(2)-M arrest and substantial apoptosis are observed following exposure to higher FP concentrations. After treatment with FP, ALL cell lines have decreased expression of retinoblastoma protein phosphorylated at serines 795 and 807/811, indicating reduced CDK activity. We also show that ALL cell lines are sensitive to clinically achievable concentrations of FP in medium supplemented with human serum and that FP reduces the expression of Mcl-1 and phosphorylated forms of the C-terminal domain of RNA polymerase II. FP also increases cell death by approximately twofold over baseline in primary ALL blasts.. These data provide a biological rationale for testing FP in relapsed ALL.

Topics: Antineoplastic Agents; Apoptosis; Blotting, Western; Cell Cycle; Cell Line, Tumor; Flavonoids; Humans; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Proteins; Neoplasm Recurrence, Local; Piperidines; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Retinoblastoma Protein; RNA Polymerase II

The in vitro efficacies of three new drugs--clofarabine (CLOF), nelarabine (NEL) and flavopiridol (FP) - were assessed in a panel of acute lymphoblastic leukaemia (ALL) cell lines. The 50% inhibitory concentration (IC50) for CLOF across all lines was 188-fold lower than that of NEL. B-lineage, but not T-lineage lines, were >7-fold more sensitive to CLOF than cytosine arabinoside (ARAC). NEL IC50 was 25-fold and 113-fold higher than ARAC in T- and B-lineage, respectively. T-ALL cells were eightfold more sensitive to NEL than B-lineage but there was considerable overlap. FP was more potent in vitro than glucocorticoids and thiopurines and at doses that recent phase I experience predicts will translate into clinical efficacy. Potential cross-resistance of CLOF, NEL and FP was observed with many front-line ALL therapeutics but not methotrexate or thiopurines. Methotrexate sensitivity was inversely related to that of NEL and FP. Whilst NEL was particularly effective in T-ALL, a subset of patients with B-lineage ALL might also be sensitive. CLOF appeared to be marginally more effective in B-lineage than T-ALL and has a distinct resistance profile that may prove useful in combination with other compounds. FP should be widely effective in ALL if sufficient plasma levels can be achieved clinically.

Topics: Adenine Nucleotides; Antineoplastic Agents; Arabinonucleosides; Burkitt Lymphoma; Child; Clofarabine; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Flavonoids; Humans; Inhibitory Concentration 50; Leukemia-Lymphoma, Adult T-Cell; Piperidines; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Tumor Cells, Cultured

The survival of adults with acute leukemias remains unsatisfactory and requires new treatment approaches. Flavopiridol modulates cell cycle progression, inhibits transcription, and induces apoptosis. We designed an in vitro model of timed sequential therapy for acute leukemia to determine whether flavopiridol can: (a). trigger apoptosis in fresh acute leukemia; and (b). recruit surviving leukemic cells to a proliferative state, thereby priming such cells for the S-phase-related cytotoxicity of 1-beta-D-arabinofuranosylcytosine (ara-C).. Bone marrow cells from 20 adults with relapsed and refractory acute leukemias were enriched for blasts by Ficoll Hypaque sedimentation. Blasts were cultured on day 0 in flavopiridol 250 nM for 24 h, removed from flavopiridol for 24 h, and then cultured in ara-C 1 microM for an additional 72 h (F(250)A(1)). Apoptosis and cell cycle phase distribution were estimated from cells stained with propidium iodide. Cell survival was determined after the 72 h ara-C exposure by double cytofluorescence assay with fluorescein diacetate and propidium iodide.. Flavopiridol induced a 4.3-fold increase in apoptosis in human leukemia samples within the first 24 h of culture. Subsequent removal of flavopiridol led to a 1.7-fold increase in the proportion of cells in S phase by day 2. Mean survival in F(250)A(1) cultures after 72 h exposure to ara-C was 35.6% compared with flavopiridol alone (F(250)A(0), 56.1%; P = 0.0003) and ara-C alone (F(0)A(1), 65.2%; P < 0.00001).. Flavopiridol induces apoptosis in marrow blasts from patients with refractory acute leukemias. Furthermore, flavopiridol pretreatment increases the proapoptotic and cytotoxic effects of ara-C. The advantage of sequential FP(250)A(1) over either agent alone is seen for both acute myelogenous leukemia and acute lymphoblastic leukemia. These findings support a clinical trial of timed sequential therapy where flavopiridol is given for cytoreduction and subsequent priming of remaining leukemic cells for enhanced cycle-dependent drug cytotoxicity.

Topics: Adult; Aged; Antineoplastic Agents; Apoptosis; Bone Marrow Cells; Cell Division; Cell Survival; Coloring Agents; Female; Flavonoids; HL-60 Cells; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; Piperidines; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Propidium; S Phase; Time Factors; Tumor Cells, Cultured