Outcome of induction and postremission therapy in younger adults with acute myeloid leukemia with normal karyotype: a cancer and leukemia group B study.

PURPOSE: Evaluate the outcome of induction and postremission therapy in adults younger than 60 years with normal cytogenetics acute myeloid leukemia (AML). PATIENTS AND METHODS: In 490 patients, induction included cytarabine and daunorubicin (AD) or cytarabine and escalated doses of daunorubicin and etoposide +/- PSC-833 (ADE/ADEP). Intensification included one cycle of high-dose cytarabine (HDAC) followed by etoposide/cyclophosphamide and mitoxantrone/diaziquone (group I), three HDAC cycles (group II), four intermediate-dose cytarabine (IDAC) or HDAC cycles (group III), or one HDAC/etoposide cycle and autologous stem-cell transplantation (ASCT; group IV). RESULTS: Of 350 patients receiving AD, 73% achieved complete remission (CR), compared with 82% of 140 receiving ADE/ADEP (P = .04). Splenomegaly was associated with a lower CR rate (P < .001), and ADE/ADEP, with a higher CR rate in younger patients (P = .005). The 5-year disease-free survival (DFS) rate was 28% each for intensification groups I and II, compared with 41% and 45% for groups III and IV, respectively (P = .02). The 5-year cumulative incidence of relapse (CIR) was 62% and 67% for groups I and II, respectively, compared with 54% and 44% for groups III and IV, respectively (P = .049). The type of postremission intensification remained significant for DFS and CIR in multivariable analysis. CONCLUSION: In younger adults with normal cytogenetics AML, splenomegaly predicts a lower CR rate, and the postremission strategies of either four cycles of I/HDAC or one cycle of HDAC/etoposide followed by ASCT are associated with improved DFS and reduced relapse compared with therapies that include fewer cycles of cytarabine or no transplantation.     

Mitoxantrone and cytarabine induction, high-dose cytarabine, and etoposide intensification for pediatric patients with relapsed or refractory acute myeloid leukemia: Children's Cancer Group Study 2951.

PURPOSE: To evaluate the response rate, survival, and toxicity of mitoxantrone and cytarabine induction, high-dose cytarabine and etoposide intensification, and further consolidation/maintenance therapies, including bone marrow transplantation, in children with relapsed, refractory, or secondary acute myeloid leukemia (AML). To evaluate response to 2-chlorodeoxyadenosine (2-CDA) and etoposide (VP-16) in patients who did not respond to mitoxantrone and cytarabine. PATIENTS AND METHODS: Patients with relapsed/refractory AML (n = 101) and secondary AML (n = 13) were entered. RESULTS: Mitoxantrone and cytarabine induction achieved a remission rate of 76% for relapsed/refractory patients and 77% for patients with secondary AML, with a 3% induction mortality rate. Cytarabine and etoposide intensification exceeded the acceptable toxic death rate of 10%. The response rate of 2-CDA/VP-16 was 8%. Two-year overall survival was estimated at 24% and was better than historical control data. Patients with secondary AML had similar outcomes to relapsed or refractory patients. Initial remission longer than 1 year was the most important prognostic factor for patients with primary AML (2-year survival rate, 75%), whereas for patients with primary AML, with less than 12 months of initial remission, survival was 13% and was similar to that of refractory patients (6%). CONCLUSION: Mitoxantrone and cytarabine induction is effective with reasonable toxicity in patients with relapsed/refractory or secondary AML. The cytarabine and etoposide intensification regimen should be abandoned because of toxicity. Patients with relapsed AML with initial remissions longer than 1 year have a relatively good prognosis.     

Postremission chemotherapy for adults with acute myelogenous leukemia: improved survival with high-dose cytarabine and daunorubicin consolidation treatment.

Results of postremission chemotherapy for adults with acute myelogenous leukemia (AML) were assessed in two sequential prospective studies involving similar induction therapy and two courses of intensive consolidation treatment. Fifty-six patients achieving remission on the acute leukemia protocol (ALP3) study received high-dose cytarabine and daunorubicin as course one and standard-dose cytarabine and daunorubicin as course two. Results are compared with forty-six patients achieving remission on the ALP2 study who received azacitidine and doxorubicin as consolidation course one and standard-dose cytarabine, daunorubicin, and thioguanine as course two. The ALP3 regimen resulted in a significantly improved 5-year disease-free survival of 32% +/- 19% versus 20% +/- 11% for the ALP2 study (P = .03). Survival from remission was also improved, 40% +/- 14% versus 24% +/- 12% (P less than .01). Favorable prognostic factors for disease-free survival included receiving the ALP3 treatment regimen, absence of a prior preleukemic syndrome, and female sex. These factors and younger patient age were significant for survival following first chemotherapy and survival after achieving remission. Six of 34 patients who relapsed after receiving the ALP3 regimen successfully achieved prolonged second remissions with high-dose cytarabine-based chemotherapy and/or allogeneic bone marrow transplantation (BMT). Overall survival for adults less than or equal to 45 years of age was 58% +/- 19% with the ALP3 postremission chemotherapy regimen, comparable to most studies of BMT for AML in first remission. Actuarial 5-year survival for ALP3 patients greater than 60 years of age was 18% +/- 20% with no improvement compared with ALP2.     

Impact of addition of maintenance therapy to intensive induction and consolidation chemotherapy for childhood acute myeloblastic leukemia: results of a prospective randomized trial, LAME 89/91. Leucámie Aiqüe Myélo?de Enfant.

PURPOSE: To determine whether the use of maintenance therapy (MT) delivered after intensive induction and consolidation therapy confers any advantage in childhood acute myeloid leukemia (AML). PATIENTS AND METHODS: A total of 268 children with AML were registered in the Leucámie Aiqu? Myélo?de Enfant (LAME) 89/91 protocol. This regimen included an intensive induction phase (mitoxantrone plus cytarabine) and, for patients without allograft, two consolidation courses, one containing timed-sequential high-dose cytarabine, asparaginase, and amsacrine. In the LAME 89 pilot study, patients were given an additional MT consisting of mercaptopurine and cytarabine for 18 months. In the LAME 91 trial, patients were randomized to receive or not receive MT. RESULTS: A total of 241 (90%) of 268 patients achieved a complete remission. The overall survival and event-free survival at 6 years were 60% +/- 6% and 48% +/- 6%, respectively. For the complete responders after consolidation therapy, the 5-year disease-free survival was not significantly different in MT-negative and in MT-positive randomized patients (respectively, 60% +/- 19% v 50% +/- 15%; P =.25), whereas the 5-year overall survival was significantly better in MT-negative randomized patients (81% +/- 13% v 58% +/- 15%; P =.04) due to a higher salvage rate after relapse. CONCLUSION: More than 50% of patients can be cured of AML in childhood. Either drug intensity or each of the induction and postremission phases may have contributed to the outstanding improvement in outcome. Low-dose MT is not recommended. Exposure to this low-dose MT may contribute to clinical drug resistance and treatment failure in patients who experience relapse.     

Patients with t(8;21)(q22;q22) and acute myeloid leukemia have superior failure-free and overall survival when repetitive cycles of high-dose cytarabine are administered.

PURPOSE: To examine the effect of single compared with repetitive (at least three) cycles of high-dose cytarabine after induction therapy for patients with acute myeloid leukemia (AML) who have the t(8;21)(q22;q22) karyotype. PATIENTS AND METHODS: Patients entered onto the study had AML and t(8;21) and attained a complete remission on four successive Cancer and Leukemia Group B studies. In these studies, either > or = three cycles of high-dose cytarabine or one cycle of high-dose cytarabine was administered, followed by sequential cyclophosphamide/etoposide and mitoxantrone/diaziquone with or without filgrastim support. Outcomes of these two groups of t(8;21) patients were compared. RESULTS: A total of 50 patients with centrally reviewed AML and t(8;21) were assigned to receive one (n = 29) or > or = three cycles (n = 21) of high-dose cytarabine as postinduction therapy. The clinical features of these two groups of patients were similar. Initial remission duration for t(8;21) patients assigned to one cycle of high-dose cytarabine was significantly inferior (P =.03), with 62% of patients experiencing relapse with a median failure-free survival of 10.5 months, compared with the group of patients who received > or = three cycles, in which only 19% experienced relapse and failure-free survival is estimated to be greater than 35 months. Furthermore, overall survival was also significantly compromised (P =.04) in patients assigned to one cycle of high-dose cytarabine, with 59% having died as a consequence of AML, compared with 24% of those who received > or = three cycles of high-dose cytarabine. CONCLUSION: These data demonstrate that failure-free survival and overall survival of patients with t(8;21)(q22;q22) may be compromised by treatment approaches that do not include sequential high-dose cytarabine therapy.     

Amsacrine, cytarabine and etoposide in the treatment of bad prognosis acute myeloid leukemia

Thirty-seven patients (median age 50 yr, range 17-82) with acute myeloid leukemia (AML) received intensive induction treatment with amsacrine, cytarabine and etoposide in combination. Nine of the patients were refractory to previous induction therapy, 15 relapsed during or after treatment with daunorubicin and cytarabine, 13 had AML after previous hematologic disorders. Eleven of the patients with AML after previous hematologic disorders had been treated with cytotoxic drugs. Toxicity was substantial, but complete remission (CR) was achieved in 33% of patients with refractory AML, 47% of patients with AML in relapse, 54% of patients with AML after antecedent blood disorder. CR duration was 15 weeks (median). Patients with AML of FAB types M4 and M5 entered remission more often (70%) than patients with other AML types (37%).     

Phase II evaluation of a high-dose mitoxantrone based induction regimen in untreated adults with acute myeloid leukemia

To evaluate a regimen including high-dose mitoxantrone in previously untreated adults with AML, 45 patients aged 21-59 (median 41) were given cytarabine, 3 g/m2 days 1-5, mitoxantrone, 80 mg/m2 day 2 and etoposide, 150 mg/m2 days 1,3,5. Post-remission therapy consisted of 5 cycles combining the same agents at reduced doses. Complete remission was seen in 36 patients. The observed 3-year survival is 28%. Cytogenetic pattern and CD34 expression correlated with response and survival. Significant toxicity included myelosuppression, mucositis, diarrhea and hyperbilirubinemia. Ventricular ejection fraction was generally reduced, with clinical cardiac dysfunction in only 2 patients. This high-dose mitoxantrone combination can be administered to young adults with AML with tolerable toxicity and results comparable to those of other dose-intensive regimens.     

Synergistic effects of troglitazone in combination with cytotoxic agents in acute myelogenous leukaemia cells

We have previously shown that troglitazone (TG) induces apoptosis in acute myelogenous leukaemia (AML) cell lines. Here we show that normal bone marrow and mobilized peripheral blood progenitors are highly resistant to TG at concentrations up to 100 microM, while primary cultures of AML bone marrow show significant decline in viability at >7.5 microM TG. The combination of standard cytotoxic agents (daunorubicin, etoposide, and cytarabine) with TG is synergistic in six AML cell lines, with the strongest synergy being exhibited when cells are pretreated with TG for 24h prior to addition of the cytotoxic agent. Significant declines in IC(50) for the cytotoxic agents are seen at nanomolar concentrations of TG. The in vitro synergy between TG and the cytotoxic drugs used in AML therapy provides a basis for in vivo evaluation of these combinations.     

Effect of etoposide added to individualized induction therapy of adult acute myeloid leukemia--the JALSG-AML-92 Study. Japan Adult Leukemia Study Group

A multicenter prospective randomized study was undertaken to assess the efficacy of etoposide added to the standard remission induction therapy for acute myeloid leukemia (AML). Consecutively registered newly diagnosed adult AML patients were randomized to receive either daunorubicin (40 mg/m2/day x 4 or more), behenoyl cytarabine (200 mg/m2/day x 10 or more) and 6-mercaptopurine (70 mg/m2/day x 10 or more) (BH-AC-DM), or the same three drugs plus etoposide (100 mg/m2/day x 5) (BH-AC-EDM) for response-oriented individualized induction therapy. The patients achieving complete remission (CR) received the same 3 courses of consolidation therapy followed by 6 courses of maintenance/intensification therapy. M3 was excluded and M0 was included. Of 667 patients registered, 655 were evaluable. The median age was 49 years (range, 15 to 85). CR rates were 77% in the BH-AC-DM group and 75% in the BH-AC-EDM group. In M4 patients, CR rates were 86% and 69% (p = 0.009), and, in M5, 80% and 77% (p = 0.810) in the BH-AC-DM and BH-AC-EDM groups, respectively. The predicted 6-year overall survival rates were 30% and 38% for BH-AC-DM and BH-AC-EDM groups, and the disease-free survival (DFS) rates of CR patients were 25% and 35% (p = 0.925), respectively. In conclusion, the present study failed to show any advantage of the addition of etoposide to the standard individualized induction therapy in adult AML, even among M4 and M5. These above data have already been published in the Int J Hematol (70: 87-104, 1999).     

Improved treatment results for childhood acute myeloid leukemia in Taiwan.

To improve treatment results for children with de novo acute myeloid leukemia (AML), we introduced a novel protocol, Taiwan Pediatric Oncology Group-AML-97A, for AML other than acute promyelocytic leukemia (APL), for which modified conventional protocols were used. From January 1, 1997, to December 31, 2002, 141 children younger than 17 years old with de novo AML were enrolled. In total, 117 patients with non-APL AML were treated with induction therapy of idarubicin and cytarabine (Ara-C), postremission therapy with high-dose Ara-C - containing regimens for four monthly courses, and moderate-dose therapy with idarubicin and Ara-C for four monthly courses. The first 19 patients with APL were treated with all-trans retinoic acid, idarubicin and Ara-C, with the remaining five patients receiving all-trans retinoic acid and idarubicin, followed by maintenance therapy for 2 years. Stem cell transplantation was performed in 29 patients in first remission with a similar outcome as chemotherapy alone. The remission rate in the AML-97A study was 90%, the 5-year survival 51 +/- 5.3% (s.e.) and the 5-year event-free survival 50 +/- 4.8%; for APL, these were 100%, 86 +/- 7.0, and 75 +/- 9.8%. For the whole group, the 5-year survival was 57 +/- 4.7% and the 5-year event-free survival 54 +/- 4.4%. The AML-97A regimen was well tolerated.     

Impact of treatment on the outcome of acute myeloid leukemia with inversion 16: a single institution's experience.

To identify treatment factors that may affect the survival of children with inv(16)(p13.1q22), we compared the outcomes of 19 patients with this genetic feature treated at our institution during two treatment eras. Nine patients were treated during era 1 (1980 to 1987), and 10 were treated during era 2 (1988 to 1996). All entered complete remission (CR) with induction therapy. Eight of the nine children treated in era 1 died, seven of relapsed leukemia. In contrast, three of 10 patients treated during era 2 have died, all of non-disease-related causes. Event-free survival (EFS) estimates were significantly higher for patients treated during era 2 than for those treated during era 1 (P = 0.03); the 6-year estimates were 70 +/- 15% (s.e.) and 11 +/- 7%, respectively. Era 2 treatment protocols differed from those of era 1 in their use of higher doses of cytarabine and etoposide during induction and consolidation chemotherapy and in their use of 2-chlorodeoxyadenosine (2-CDA). These results suggest that dose intensification of cytarabine benefits children with AML and inv(16), as is the case in adults. They also suggest that dose intensification of etoposide and addition of 2-CDA may also offer an advantage. This study underscores the dependence of the prognostic impact of cytogenetic features on the efficacy of treatment.     

Continuous drip infusion of low dose cytarabine and etoposide with granulocyte colony-stimulating factor for elderly patients with acute myeloid leukaemia ineligible for intensive chemotherapy

BACKGROUNDS AND OBJECTIVES: The optimal strategy for the management of elderly patients with acute myeloid leukaemia (AML) is still controversial. We previously reported the effectiveness of low dose cytarabine (Ara-C) and etoposide (VP-16) (AV therapy) for those elderly AML patients ineligible for intensive chemotherapy. We initiated the present feasibility study to improve the efficacy by using glanulocyte-colony stimulating factor (G-CSF) with AV therapy (AVG therapy). PATIENTS AND METHODS: The eligibility for enrolment was AML patients according to the World Health Organization (WHO) criteria who were over 60 years of age and who had difficulty in tolerating intensive chemotherapy due to their poor performance status (PS) or some comorbidities. They were given continuous drip infusion of Ara-C (20 mg/body) and VP-16 (50 mg/body) for 7-14 days, and were also simultaneously administered G-CSF (150 microg/m2) once daily. RESULTS: The median age of consecutively enrolled 25 patients was 73 years. Eighteen (72%) patients achieved complete remission (CR). The 1-year overall survival (OS) and the 3-year OS rates were 69% and 22%, respectively. The 1-year disease free survival (DFS) rate in CR patients was 44%. The major regimen related toxicities of grade 3 or 4 were only febrile neutropenia in 15 patients (60%). No regimen-related mortality was observed. CONCLUSION: AVG therapy was therefore found to be an effective and well-tolerated regimen for remission induction in elderly AML patients with poor PS or comorbidity.     

Results of treatment with an intensive induction regimen using idarubicin in combination with cytarabine and etoposide in children with acute myeloblastic leukemia

We report results achieved in our institution with a study opened in July 1990 (similar to the German AML-BFM-87 in which daunorubicin was replaced by idarubicin in the induction phase and cranial preventive radiotherapy was omitted) and closed in December 1994, for the treatment of newly diagnosed acute myeloblastic leukemia (AML), without prior malignancies except for myelodysplasia.This evaluation included 68 patients, whose mean age was 6 years (range: 1 month–16 years). Thirty-nine were boys and 29 were girls. Complete remission rate was 80.9% (55/68), death on induction rate was 14.7% and induction failure rate was 4.4%. At median follow up of 38 months (range: 12–66 months), the 4-year event-free survival (EFS) estimate was 0.428 (S.E.: 0.062), event-free interval (EFI) estimate was 0.529 (S.E.: 0.07) and overall survival (OS) estimate was 0.44 (S.E.: 0.071).We conclude that idarubicin in combination with cytarabine and etoposide is a highly effective regimen for induction in children with AML. Although preventive cranial irradiation was not delivered, we have observed only one combined CNS relapse. Finally, we corroborate that in this setting two definite risk groups may be identified in children with AML.     

High-dose mitoxantrone in acute leukaemia: New York Medical College experience

Based on promising preclinical data, a progressive series of evaluations of the use of high-dose mitoxantrone-based chemotherapy was initiated in acute leukaemia patients. A preliminary phase I study demonstrated that up to 80 mg/m² of mitoxantrone in combination with cytarabine 3 g/m² daily for 5 days could be given as induction therapy to leukaemic patients with acceptable toxicity. Pharmacokinetic data from these patients demonstrated that high concentrations of mitoxantrone were achievable in vivo to levels that were extremely cytotoxic in vitro. Subsequently, in a phase II study, 45 patients with untreated acute myelogenous leukaemia (AML) under the age of 60 received mitoxantrone 80 mg/m² in combination with cytarabine 3 g/m² daily for 5 days and etoposide 150 mg/m² for 3 days. Following this induction, patients received five cycles of consolidation with cytarabine 3 g/m² daily for 4 days with mitoxantrone 20 mg/m² for 1 day on cycles 2 and 4, and etoposide 150 mg/m² for 2 days with cytarabine on courses 1,3 and 5. The patients in this study achieved a complete remission (CR) rate of 80% and a 3-year projected probability of survival of 40%. In a second AML study, 54 adults over the age of 60 with untreated AML were randomized to receive either high-dose or standard-dose mitoxantrone with cytarabine as a single induction regimen without consolidation. Patients receiving high-dose mitoxantrone did not experience increased morbidity or mortality compared with those given lower doses. Comparison of CR rates, disease-free and overall survival consistently favoured high-dose mitoxantrone, although the results did not achieve statistical significance. In patients with acute lymphocytic leukaemia (ALL), high-dose mitoxantrone with cytarabine was given as initial therapy in a phase II study involving 37 previously untreated adults. Results demonstrated that this dose-intensive regimen could produce a high CR rate (84%) with acceptable toxicity and compared favourably with experiences with vincristine/prednisone-based induction regimens. These studies demonstrate that high-dose mitoxantrone can be safely and effectively administered to patients with acute leukaemia and suggest that the incorporation of high doses of mitoxantrone into treatment regimens may lead to enhanced antileukaemic efficacy compared with standard doses. Phase III evaluations are planned.     

Acute myeloid leukemia 4 years after Kaposi's sarcoma in a renal transplant recipient

BACKGROUND: Leukemia is a well-known complication of cancer therapy, but development of acute myeloid leukemia (AML) after renal transplantation is rare. Immunosuppressive therapy for organ transplant recipients is complicated by high rates of malignant disease, one condition being Kaposi's sarcoma (KS). CASE REPORT: A 22-year-old woman developed KS 1 year after renal transplantation, and then developed AML another 4 years later. When KS was diagnosed it was already in extensive stage, and she received ABV combination chemotherapy with doxorubicin plus bleomycin plus vincristine intravenously (i.v.) once daily every 2 weeks. She entered remission but the KS relapsed and 8 cycles of i.v. etoposide monotherapy were given and she re-entered remission. 19 months later, the patient was admitted to hospital with severe malaise, leukocytosis, thrombocytopenia, and anemia. The diagnosis was AML (FABM4). The patient received induction chemotherapy consisting of cytarabine and idarubicin. After completion of this induction therapy she developed neutropenic infection, dyspnea and confusion. Her condition deteriorated rapidly after that, and she died. CONCLUSION: KS is one of the most common malignancies in renal allograft recipients, whereas AML is a less frequent problem. To our knowledge, this is the first published case of these two different malignancies developing after renal transplantation. The pathogenesis of the AML is discussed.     

Combination of tetrandrine as a potential-reversing agent with daunorubicin, etoposide and cytarabine for the treatment of refractory and relapsed acute myelogenous leukemia

The potential mechanism of the chemotherapy resistance in acute myeloid leukemia (AML) is the multidrug resistance (MDR-1) gene product P-glycoprotein (P-gp), which is often overexpressed in myeloblasts from acute myeloid leukemia. In a multicenter clinical trial, 38 patients with poor risk forms of AML were treated with tetrandrine (TET), a potent inhibitor of the MDR-1 efflux pump, combined with daunorubicin (DNR), etoposide and cytarabine (TET-DEC). Overall, post-chemotherapy marrow hypoplasia was achieved in 36 patients. Sixteen patients (42%) achieved complete remission or restored chronic phase, 9 achieved partial remission (PR) and 13 failed therapy. Toxicities included infection, myelosuppression, stomatitis, mucositis, cerebellar toxicity and reversible cardiotoxicity. There was no significant difference in response for P-gp-positive and -negative patients. P-gp function was assessed in 26 patients by flow cytometric analysis, TET-contained plasma-augmented DNR accumulation relative to pretreatment plasma in K562/A02 cells by a median value of 88+/-101% (range, 11-501%). However, there was no difference in DNR uptake between responding and non-responding patients. Our data showed that TET-DEC was relatively well tolerated in these patients with poor risk AML, and had encouraging antileukemic effects.     

Continuous infusion intermediate-dose cytarabine, mitoxantrone, plus etoposide for refractory or early relapsed acute myelogenous leukemia

For refractory and early relapsed AML, this prospective phase II clinical trial evaluated a salvage chemotherapy regimen, which was consisted of continuous infusion intermediate-dose cytarabine (1g/m(2)/day, 24h i.v. infusion x 5), mitoxantrone (12 mg/m(2)/day x 3), and etoposide (150 mg/m(2)/day x 3). We treated 33 patients and 17 (51.5%) achieved CR with a median duration of 117 days. Median overall survival was 219 days. Our results suggest that continuous infusion intermediate-dose cytarabine, together with mitoxantrone and etoposide, may induce CR in a significant proportion of patients with refractory or early relapsed AML, although remission duration was short.     

The schedule-dependent effects of etoposide in leukaemic cell lines: a function of concentration and duration

PURPOSE: Etoposide is a commonly used anticancer agent that is highly schedule-dependent. The in vitro activity of etoposide (0-10 microM) was investigated in a panel of leukaemic cell lines. METHODS: Cells were cultured with etoposide in drug schedules of equal exposure duration (ED, durationxconcentration), and the effects of drug exposure on cell parameters, including cell cycle distribution, were assessed over an 8-day period. RESULTS: Proliferation assays indicated a concentration- and duration-dependent induction of cell death by etoposide in CEM and HL60 cells, and flow cytometric analysis indicated that this cell kill was by apoptosis. Efficacy was also dependent upon schedule, with more cell kill seen in schedules of longer duration. As an example, accumulative percent cell kill resulting from a continuous exposure to 0.05 microM etoposide was significantly greater than that in cultures involving either a 4-day exposure to 0.1 microM or a single-day exposure to 0.4 microM etoposide (193.4+/-15.9% vs 125.2+/-5.4% vs 42.3+/-5.9%, respectively; P<0.001 in all cases; equi-ED 0.4 microM.days). Efficacy was also dependent upon the ED of the schedule. At very low concentrations, the initial enhancement of cytotoxicity mediated by increasing duration would gradually and paradoxically be lost in the more protracted schedules (e.g. accumulative percent cell kill 66.4+/-7.4%, 158.3+/-12.0% and 40.1+/-6.0% with 100 n M for 2 days, 33 n M for 6 days and 25 n M for 8 days, respectively; P<0.001 in all cases; equi-ED 0.2 microM x days). CONCLUSIONS: Our results confirm the schedule-dependency of etoposide in vitro, highlighting the importance of total duration of drug exposure in determining cytotoxicity, and emphasizing the requirement to achieve a cytotoxic concentration in longer exposures. It is therefore crucial to ensure that etoposide regimens used clinically involve doses that are effectively cytotoxic.     

Single-dose mitoxantrone in combination with continuous infusion intermediate-dose cytarabine plus etoposide for treatment of refractory or early relapsed acute myeloid leukemia

This prospective phase II clinical trial evaluated the effects of single-dose mitoxantrone (36 mg/m2 on day 1) in combination with continuous infusion intermediate-dose cytarabine plus etoposide in 25 patients with refractory or early relapsed acute myeloid leukemia (AML). We compared the results of our current study with those of a previous phase II trial, which had the same eligibility criteria and chemotherapy schedule except that a conventional divided dose of mitoxantrone (12 mg/m2 on days 1-3) was used. The complete remission (CR) rate was significantly lower with the single-dose mitoxantrone regimen than with the divided-dose regimen (24.0% vs. 51.5%; P=0.034), mainly owing to an increased incidence of hypoplastic deaths. CR duration and overall survival were not significantly different between the two regimens. In conclusion, single-dose mitoxantrone was inferior to conventional divided-dose mitoxantrone for treatment of refractory or early relapsed AML in terms of CR rate.