alvocidib and fludarabine

Early phase studies of alvocidib showed activity in relapsed CLL including patients with high risk genomic features and those refractory to fludarabine. A multi-center, international, phase II study of alvocidib in fludarabine refractory CLL was undertaken to validate these early results. Patients with fludarabine refractory CLL or prolymphocytic leukemia arising from CLL were treated with single agent alvocidib. The primary outcome measure was overall response rate, with secondary outcomes including survival, toxicity, and response duration. One hundred and sixty five patients were enrolled and 159 patients were treated. The median age was 61 years, the median number of prior therapies was 4, and 96% of patients were fludarabine refractory. The investigator-assessed overall response rate was 25%; the majority of responses were partial. Response rates were lower among patients with del(17p) (14%), but equivalent in patients with del(11q) or bulky lymphadenopathy. Median progression free and overall survival were 7.6 and 14.6 months, respectively. Tumor lysis occurred in 39 patients (25%), and 13 received hemodialysis. Diarrhea, fatigue, and hematologic toxicities were common. Alvocidib has clinical activity in patients with advanced, fludarabine refractory CLL. Future studies should focus on discovery of biomarkers of clinical response and tumor lysis, and enhanced supportive care measures.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Female; Flavonoids; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Male; Middle Aged; Piperidines; Recurrence; Survival Analysis; Treatment Failure; Vidarabine

Flavopiridol downmodulates antiapoptotic proteins associated with resistance to fludarabine and rituximab and is effective against p53-mutated chronic lymphocytic leukemia (CLL). We conducted a phase I study of flavopiridol, fludarabine, and rituximab (FFR) in patients with mantle-cell lymphoma (MCL), indolent B-cell non-Hodgkin's lymphomas (B-NHL), and CLL to determine the activity of FFR.. Therapy included fludarabine 25 mg/m(2) intravenously (IV) days 1 to 5 and rituximab 375 mg/m(2) day 1 every 28 days for 6 cycles. We administered flavopiridol 50 mg/m(2) by 1-hour IV bolus (IVB) day 1 (n = 15); day 1 to 2 (n = 6); 20 mg/m(2) 30-minute IVB + 20 mg/m(2) 4-hour IV infusion (n = 3); or 30 mg/m(2) + 30 mg/m(2) (n = 14).. Thirty-eight patients (median age, 62 years) with MCL (n = 10); indolent B-NHL including follicular (n = 9), marginal zone (n = 4), lymphoplasmacytic (n = 1), or small lymphocytic lymphoma (n = 3); and CLL (n = 11), were enrolled. Twenty-two patients were previously untreated; 16 had received one to two prior therapies. Two patients in cohort 2 developed grade 3 dose-limiting toxicity (seizures, renal insufficiency). The median number of treatment cycles was 4, with cytopenias (n = 10) and fatigue (n = 3) the most common reasons for early discontinuation. Overall response rate was 82% (complete response, 50%; unconfirmed complete response, 5%; partial response, 26%), including 80% of patients with MCL (median age, 68; seven complete responses, one partial response). Median progression-free survival (PFS) was 25.6 months. Median PFS of patients with nonblastoid variant MCL (n = 8) was 35.9 months.. FFR was active in MCL, indolent B-NHL, and CLL and should be studied for older patients with MCL who are not candidates for aggressive chemotherapy.

Topics: Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal; Antibodies, Monoclonal, Murine-Derived; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; B-Lymphocytes; Female; Flavonoids; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphoma, B-Cell; Lymphoma, Mantle-Cell; Lymphoproliferative Disorders; Male; Middle Aged; Piperidines; Rituximab; Vidarabine

We previously reported interim results of a phase 1 trial in patients with chronic lymphocytic leukemia (CLL) whereby flavopiridol was administered intravenously as a 30-minute bolus followed by 4-hour infusion. We now report full pharmacokinetic (PK) data, correlations of PK with clinical outcomes, and final response and progression-free survival (PFS). Twenty-one (40%) of 52 patients with relapsed CLL achieved a partial response (PR) with a median PFS of 12 months. Responders included 17 (40%) of 43 fludarabine refractory patients, 7 (39%) of 18 patients with del(17p13), and 14 (74%) of 19 patients with del(11q22). Six responders received repeat therapy at relapse, and 5 responded again with a second median PFS of 10 months. Noncompartmental analysis and nonlinear mixed effects modeling was used to estimate PK parameters and evaluate covariates. Two-compartment population parameter estimates were 31.4 L/h, 65.8 L, 8.49 L/h, and 157 L for CL, V1, Q, and V2, respectively. Flavopiridol area under the plasma concentration-time curve (AUC) correlated with clinical response and cytokine release syndrome, and glucuronide metabolite AUC correlated with tumor lysis syndrome. These composite results confirm high activity of this pharmacokinetically derived schedule in relapsed, genetically high-risk CLL. Furthermore, PK describes some, but not all, variability in response and toxicity.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Area Under Curve; Cell Cycle; Disease-Free Survival; Drug Resistance, Neoplasm; Female; Flavonoids; Humans; Inactivation, Metabolic; Infusions, Intravenous; Injections, Intravenous; Leukemia, Lymphocytic, Chronic, B-Cell; Male; Middle Aged; Models, Biological; Piperidines; Protein Kinase Inhibitors; Recurrence; Salvage Therapy; Treatment Outcome; Tumor Lysis Syndrome; Uridine Diphosphate Glucuronic Acid; Vidarabine

Cyclin dependent kinase (CDK) inhibitors, such as flavopiridol, demonstrate significant single-agent activity in chronic lymphocytic leukemia (CLL), but the mechanism of action in these nonproliferating cells is unclear. Here we demonstrate that CLL cells undergo autophagy after treatment with therapeutic agents, including fludarabine, CAL-101, and flavopiridol as well as the endoplasmic reticulum (ER) stress-inducing agent thapsigargin. The addition of chloroquine or siRNA against autophagy components enhanced the cytotoxic effects of flavopiridol and thapsigargin, but not the other agents. Similar to thapsigargin, flavopiridol robustly induces a distinct pattern of ER stress in CLL cells that contributes to cell death through IRE1-mediated activation of ASK1 and possibly downstream caspases. Both autophagy and ER stress were documented in tumor cells from CLL patients receiving flavopiridol. Thus, CLL cells undergo autophagy after multiple stimuli, including therapeutic agents, but only with ER stress mediators and CDK inhibitors is autophagy a mechanism of resistance to cell death. These findings collectively demonstrate, for the first time, a novel mechanism of action (ER stress) and drug resistance (autophagy) for CDK inhibitors, such as flavopiridol in CLL, and provide avenues for new therapeutic combination approaches in this disease.

Topics: Antineoplastic Agents; Autophagy; Cell Culture Techniques; Cyclin-Dependent Kinases; Drug Resistance, Neoplasm; Endoplasmic Reticulum Stress; Flavonoids; Gene Expression Regulation, Leukemic; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Piperidines; Protein Kinase Inhibitors; Signal Transduction; Starvation; Tumor Cells, Cultured; Vidarabine

Topics: Animals; Antineoplastic Agents; Disease Models, Animal; Disease Progression; Flavonoids; Gene Expression Regulation, Leukemic; Humans; Leukemia; Mice; MicroRNAs; Piperidines; Prognosis; Vidarabine

Flavopiridol, a synthetic flavone, is currently under clinical investigation for the treatment of B-cell chronic lymphocytic leukaemia (B-CLL). In this study, we examined the in vitro effects of flavopiridol and fludarabine on B-CLL cells from 64 patients (36 treated and 28 untreated) in terms of apoptosis induction and Bcl-2 family expression. Both flavopiridol and fludarabine induced apoptosis in all the samples tested with mean LD(50) values (+/- SD) of 59.7 nmol/l (+/- 36.5) and 6.2 micromol/l (+/- 7.5) respectively. Mean flavopiridol LD(50) values were not significantly different between the treated and untreated patient groups (P = 0.35), whereas the fludarabine LD(50) values were significantly higher in the previously treated patient group (P = 0.01). Bcl-2 and Mcl-1 expression were downregulated in both flavopiridol and fludarabine-induced apoptotic cells, but the increase in Bax expression that accompanied fludarabine-induced apoptosis was not evident in flavopiridol-treated cells. In addition, Bcl-2:Bax ratios were not predictive of flavopiridol cytotoxicity (P = 0.82), whereas they were highly predictive of in vitro responsiveness to fludarabine (P = 0.001). Overall, these findings suggest that flavopiridol exerts its cytotoxic effect through a novel cell-death pathway that is not subject to the Bcl-2 family mediated resistance mechanisms that reduce the efficacy of many conventional chemotherapeutic drugs.

Topics: Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Drug Resistance, Neoplasm; Flavonoids; Flow Cytometry; Humans; Lethal Dose 50; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphocytes; Piperidines; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Tumor Suppressor Protein p53; Vidarabine

Flavopiridol has been reported to induce apoptosis in lymphoid cell lines via downregulation of bcl-2. The in vitro activity of flavopiridol against human chronic lymphocytic leukemia (CLL) cells and potential mechanisms of action for inducing cytotoxicity were studied. The in vitro viability of mononuclear cells from CLL patients (n = 11) was reduced by 50% at 4 hours, 24 hours, and 4 days at a flavopiridol concentration of 1.15 micromol/L (95% confidence interval [CI] +/-0.31), 0.18 micromol/L (95% CI +/-0.04), and 0.16 micromol/L (95% CI +/-0.04), respectively. Loss of viability in human CLL cells correlated with early induction of apoptosis. Exposure of CLL cells to 0.18 micromol/L of flavopiridol resulted in both decreased expression of p53 protein and cleavage of the caspase-3 zymogen 32-kD protein with the appearance of its 20-kD subunit. Contrasting observations of others in tumor cell lines, flavopiridol cytotoxicity in CLL cells did not correlate with changes in bcl-2 protein expression alterations. We evaluated flavopiridol's dependence on intact p53 by exposing splenocytes from wild-type (p53(+/+)) and p53 null (p53(-/-)) mice that demonstrated no preferential cytotoxicity as compared with a marked differential with F-ara-a and radiation. Incubation of CLL cells with antiapoptotic cytokine interleukin-4 (IL-4) did not alter the LC50 of flavopiridol, as compared with a marked elevation noted with F-ara-a in the majority of patients tested. These data demonstrate that flavopiridol has significant in vitro activity against human CLL cells through activation of caspase-3, which appears to occur independently of bcl-2 modulation, the presence of IL-4, or p53 status. Such findings strongly support the early introduction of flavopiridol into clinical trials for patients with B-CLL.

Topics: Animals; Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Caspases; Cell Cycle Proteins; Chromosomes, Human, Pair 17; Cyclin-Dependent Kinase Inhibitor p27; Drug Administration Schedule; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Enzyme Activation; Enzyme Precursors; Flavonoids; Gene Deletion; Genes, p53; Growth Inhibitors; Humans; In Situ Hybridization, Fluorescence; Interleukin-4; Leukemia, Lymphocytic, Chronic, B-Cell; Mice; Mice, Inbred C57BL; Mice, Knockout; Microtubule-Associated Proteins; Neoplasm Proteins; Piperidines; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Tumor Suppressor Proteins; Vidarabine