A phase III comparison of high dose ARA-C (HIDAC) versus HIDAC plus mitoxantrone in the treatment of first relapsed or refractory acute myeloid leukemia Southwest Oncology Group Study

Phase II evaluation of an intensified induction therapy with standard daunomycin and cytarabine followed by high dose cytarabine for adults with previously untreated acute myeloid leukemia: a Southwest Oncology Group study (SWOG-9500)

Induction therapy for acute myeloid leukemia (AML) usually consists of 7 days of cytarabine at 100-200 mg/m(2)/day and an anthracycline. Such combinations produce complete response (CR) rates of 60-80% in patients with de novo AML. On the basis of a previous report, suggesting a higher CR rate using a regimen of standard daunomycin and cytarabine followed by 3 days of high-dose cytarabine (HDAC), 101 eligible patients received this regimen in a phase II trial. Sixty patients [59%, 95% confidence interval (CI) 49-69%] achieved a CR, and 10 patients died of infection during induction. Although cytogenetic risk group affected overall survival (P = 0.0016) and relapse-free survival (P = 0.0043), it had no impact on CR rate (P = 0.63). Patients received postremission therapy with repetitive courses of alternate day high-dose cytarabine; this was associated with considerable toxicity and the majority of patients could not receive all of the scheduled postremission therapy. The estimated median survival was 23 months (95% CI 15-34 months), and the estimated probability of surviving 5 years was 34% (95% CI 24-43%). The results of this intensive induction regimen were similar to that seen in previous trials and were not as promising as reported in the previous pilot study.

Sequential response-adapted induction and consolidation regimens idarubicin/cytarabine and mitoxantrone/etoposide in adult acute myelogenous leukemia: 10 year follow-up of a study by the Canadian Leukemia Studies Group

PURPOSE

The Canadian Leukemia Studies Group (CLSG) sought to test the safety and efficacy of response-adapted, non-cross resistant chemotherapy in de novo acute myeloid leukemia (AML). The combinations of idarubicin 12 mg/m(2)/d on days 1 - 3 and Ara-C (200 mg/m(2)/d) on days 1 - 7 (IDAC) followed by mitoxantrone 10 mg/m(2)/day, and etoposide 100 mg/m(2)/day, on days 1 - 5 (NOVE) were used according to patient response to induction and consolidation.

PATIENTS AND METHODS

In this multi-centre open-label phase II study, 140 patients up to age 80 were given induction with IDAC. Patients were entered between March 1993 and August 1995. If patients had persistent blasts at day 14 or on recovery, they were given NOVE. As consolidation, patients achieving complete remission (CR) with IDAC were given 1 further cycle of IDAC and 1 cycle of NOVE. Patients achieving CR after NOVE were given 2 further cycles of NOVE.

RESULTS

76% of all patients achieved remission after IDAC +/- NOVE, 81% in patients aged < or =60 years and 67% in patients aged >60. Overall, induction mortality was 11% and toxicity was similar to other cooperative group studies. Median follow-up was 104.0 months with 95% CI: (100.0, 105.2). Median overall survival (OS) in responding patients < or =60 was not reached: of the 79 responders < or =60, 35 died. The median disease free survival (DFS) in these responding patients was 22.7 (14.9, na) months. Median OS and DFS in responding patients >60 was 10.0 (7.3, 15.2) months and 7.5 (6.2, 15.2) months, respectively.

CONCLUSION

The results of this trial are very encouraging and suggest that there may be long-term benefit to this method. On the basis of these results, a randomized phase III trial has been performed.

Aclarubicin plus behenoyl cytarabine and prednisolone for previously treated acute myeloid leukemia patients

This study analysed the clinical outcome of salvage therapy consisting of aclarubicin (ACR) plus behenoyl cytarabine (BHAC) and prednisolone (PSL) for patients with acute myeloid leukemia (AML). ACR was administered at a dose of 13 mg/m2 per day for 14 days; BHAC, at 130 mg/m2 per day for 14 days; and PSL was administered orally at a dose of 60 mg/m2 per day for 5 days. Of 47 patients, 25 (53.2%) achieved CR. The CR rates of patients in whom induction failed was 55% and that of relapsed patients was 51.9%. Four patients received allogeneic hematopoietic stem cell transplantation after achieving CR. Five patients achieved long-term survival without relapse. The 10-year relapse-free and overall survival rates were 20% and 10.6%, respectively. ACR in combination with BHAC showed a substantial anti-leukemic efficacy in previously treated AML patients and the role of ACR and BHAC may be considered while devising strategies for AML treatments.

Biology and management of relapsed acute myeloid leukaemia

Disease relapse remains the major cause of treatment failure in adults with acute myeloid leukaemia (AML). This reflects both the failure of current salvage regimens and the absence of effective strategies to secure long-term disease-free survival in those patients who achieve a second remission. Recent progress in understanding the pathogenesis of relapsed disease has enabled the identification of a variety of dysregulated molecular pathways and these now provide a rational basis for the design of novel targeted therapies. At the same time, advances in allogeneic stem-cell transplantation have permitted the extension of the curative potential of allografting to patients in whom it was previously contraindicated. As a result, a range of novel drug and transplant therapies has become available in patients with relapsed AML, and it is realistic to anticipate that a co-ordinated assessment of their clinical and biological impact will provide the basis for the design of future, more effective treatments in relapsed disease.

Drug therapy for acute myeloid leukemia

Although improvement in outcomes has occurred in younger adults with acute myeloid leukemia (AML) during the past 4 decades, progress in older adults has been much less conspicuous, if at all. Approximately 50% to 75% of adults with AML achieve complete remission (CR) with cytarabine and an anthracycline such as daunorubicin or idarubicin or the anthracenedione mitoxantrone. However, only approximately 20% to 30% of the patients enjoy long-term disease survival. Various postremission strategies have been explored to eliminate minimal residual disease. The optimal dose, schedule, and number of cycles of postremission chemotherapy for most patients are not known. A variety of prognostic factors can predict outcome and include the karyotype of the leukemic cells and the presence of transmembrane transporter proteins, which extrude certain chemotherapy agents from the cell and confer multidrug resistance and mutations in or over expressions of specific genes such as WT1, CEBPA, BAX and the ratio of BCL2 to BAX, BAALC, EVI1, KIT, and FLT3. Most recently, insights into the molecular pathogenesis of AML have led to the development of more specific targeted agents and have ushered in an exciting new era of antileukemia therapy. Such agents include the immunoconjugate gemtuzumab ozogamicin, multidrug resistance inhibitors, farnesyl transferase inhibitors, histone deacetylase and proteosome inhibitors, antiangiogenesis agents, Fms-like tyrosine kinase 3 (FLT3) inhibitors, and apoptosis inhibitors.

Fludarabine, cytosine arabinoside, granulocyte-colony stimulating factor with or without idarubicin in the treatment of high risk acute leukaemia or myelodysplastic syndromes

The combination of fludarabine (FDR), high dose cytarabine and granulocyte colony stimulating factor (FLAG) with or without idarubicin (Ida) was used in the treatment of poor risk acute leukaemia or myelodysplastic syndrome (MDS) in a single centre experience. A total of 105 patients were treated over a 4-year period with 59% achieving a complete remission (CR); no statistical difference observed between FLAG and FLAG-Ida. For patients responding to FLAG +/- Ida, the median event-free survival (EFS) was 11 months and 23% at 5 years. Such patients proceeded either to further chemotherapy or a haematopoietic stem cell transplant (HSCT). The median EFS (13 months vs. 8 months) and projected 5-year survival (37% vs. 13%) of patients undergoing HSCT was significantly better than those who did not (P = 0.021). In all, 14 of 72 patients remain alive in continuing CR (median duration 43 months) with 10 of 31 having had a HSCT vs. four of 41 that did not (P = 0.033). Both regimens were well tolerated, with the majority of patients experiencing grade 1 or less non-haematological toxicity (mainly nausea and vomiting). The median time to neutrophil and platelet recovery was 28 and 31 d, respectively. No significant differences were seen with the addition of ida. There was a 17% incidence of treatment-related deaths, of which 39% was caused by invasive aspergillus infection. The results show that FLAG +/- Ida is an effective and well-tolerated remission induction regimen for poor risk leukaemia and MDS.

High-Dose Cytarabine for Consolidation and Relapse Therapy in Acute Myelogenous Leukemia

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column focuses on the commercially available and investigational agents used to treat malignant diseases, reviewing issues related to the preparation, dispensing, and administration of cancer chemotherapy.

Efficacy and safety of gemtuzumab ozogamicin in patients with poor-prognosis acute myeloid leukemia

The objective of this work was to determine the safety and efficacy of gemtuzumab ozogamicin in patients with poor prognosis acute myeloid leukemia (AML). Patients with the following diagnoses/characteristics were treated with 1-3 infusions of gemtuzumab ozogamicin at a dose of 9 mg/m2: (1) relapse of AML < or = 6 months of first complete remission (CR); (2) AML refractory to chemotherapy at initial induction or at first relapse; (3) AML in second or greater relapse; (4) myeloid blast crisis of chronic myeloid leukemia (CML); (5) untreated patients > or = 70 years or > or = 55 years with abnormal cytogenetics (excluding inv 16, t(15;17) and t(8;21)) and/or an antecedent hematologic disorder; (6) refractory anemia with excess blasts in transformation (RAEBT). Forty-three patients, ages 19-84 (mean 62), were treated, including 7 patients with untreated AML age > 70 years, 2 with untreated RAEBT, 14 with AML first salvage (first remission 0-6 months), 15 with AML > or = second salvage and 14 with myeloid blast phase of CML. The overall response rate was 14%, with 4/43 (9%) patients achieving CR and 2/43 (5%) achieving CR without platelet recovery. The most significant toxicity was neutropenic fever, which occurred in 84% of patients. In conclusion, in patients with relapsed/refractory AML, gemtuzumab ozogamicin has a comparable response rate to single-agent chemotherapy and may offer a more favorable toxicity profile.

The treatment of acute myeloid leukemia in first relapse: a comprehensive review of the literature

Twenty years of published literature was reviewed for chemotherapy regimens used to treat patients with acute myeloid leukemia (AML) in first relapse. Thirty-one trials containing at least 20 patients in first relapse and information on patient age, duration of first complete remission (CR1), and rate of second complete remission (CR2) were analyzed. These trials included 10 retrospective studies with CR2 rates ranging from 30 to 64%, two phase II single-agent studies with CR2 rates of 8 and 25%, 15 phase II combination-agent studies with CR2 rates ranging from 14 to 87%, and four phase III randomized studies with CR2 rates ranging from 40 to 89%. When reported, median duration of CR2 was < or = 14 months and overall median survival was < or = 12 months. The probability of 3-year survival ranged from 8 to 29%. Combination therapies resulted in higher CR2 rates but were associated with longer duration of myelosuppression and greater incidence of mucositis. None of the reviewed regimens provided durable remissions for the majority of AML patients in first relapse. The CR2 rates were closely associated with age and duration of CR1. Therefore, considering the poor clinical outcomes of patients with AML in first relapse, improved therapies need to be developed.

Treatment of refractory acute leukemia with timed sequential chemotherapy using topotecan followed by etoposide + mitoxantrone (T-EM) and correlation with topoisomerase II levels

A phase I/II clinical study evaluated 17 patients with refractory/recurrent acute leukemia treated with 1.5 mg/m2/day topotecan on days 1-3 followed by etoposide (100 mg/m2/day)+mitoxantrone (10 mg/m2/day) on days 4, 5 and 9, 10. Timed sequential chemotherapy using the topoisomerase I-inhibitor topotecan before the topoisomerase II-inhibitors, etoposide+mitoxantrone (T-EM) treatment is proposed to induce topoisomerase II protein levels and potentiate the cytotoxic activity of the topoisomerase II-directed drugs. Fourteen patients had refractory and three had recurrent acute leukemia. The majority of patients were heavily pre-treated with greater than three re-induction chemotherapy regimens. Ten patients responded to T-EM treatment (59%). Four of seventeen (24%) had a complete remission and one had a partial remission. Four additional patients (24%) who scored complete leukemia clearance had no evidence of disease with complete white and red blood cell recovery but with platelet counts less than 100,000. The lack of platelet recovery in one patient having a partial response was scored as a partial leukemia clearance. The toxicity profile included major non-hematological toxicity including grade 3 mucositis (29%) and neutropenic fever (65%). Paired measurements of intracellular levels of topoisomerase II isoforms alpha and beta in leukemia blast cells (bone marrow) collected before (day 0) and after topotecan treatment (day 4) showed that a relative increase of topoisomerase IIalpha (Topo IIalpha) > or = 40% strongly correlated with response after T-EM treatment. Increased Topo IIalpha levels also corresponded to increased DNA fragmentation. Two patients who had an increase of Topo IIalpha of 20-25% had either a PR or PLC while patients with a < 10% increase showed no response to T-EM treatment. We conclude that timed sequential chemotherapy using topotecan followed by etoposide+mitoxantrone is an effective regimen for patients with refractory acute leukemia, and demonstrate Topo IIalpha protein level increases after topotecan treatment.

Use of marine toxins in combination with cytotoxic drugs for induction of apoptosis in acute myelogenous leukaemia cells

Intensive chemotherapy for acute myelogenous leukaemia (AML) results in an overall long-term disease-free survival of < 50%. This percentage reflects an improved survival for certain subsets of patients with low-risk cytogenetic abnormalities after treatment with high-dose cytarabine, whereas lower long-term survival is seen for other patients and especially for the large group of elderly patients. New treatment strategies are therefore considered in AML and one approach is to target the regulation of apoptosis in AML cells with new pharmacological agents. Regulation of apoptosis seems to be clinically important in AML as intracellular levels of apoptosis-regulating mediators can be used as predictors of prognosis in AML. It is also well documented that cytotoxic drugs exert important antileukaemic effects through induction of apoptosis. Marine toxins represent new pharmacological agents with proapoptotic effects and should be considered for combination therapy with cytotoxic drugs. These agents are already useful laboratory tools for in vitro studies of AML cells but it is still too early to conclude whether they will become useful in clinical therapy. One of the major problems to be investigated is the toxicity of combination therapy, although this may be solved by the coupling of toxins to antibodies or growth factors with a preferential binding to AML cells. Other problems that have to be addressed are the possible effect of the toxins' tumour promoting effects on chemosensitivity in relapsed AML and the possibility of cross-resistance between cytotoxic drugs and toxins.

Mylotarg: antibody-targeted chemotherapy comes of age

Mylotarg (gemtuzumab ozogamicin, CMA-676; Wyeth-Ayerst Laboratories, Philadelphia, PA) recently was approved by the US Food and Drug Administration for the treatment of patients with CD33-positive acute myeloid leukemia in first relapse, age 60 years or older, who are not considered candidates for other types of cytotoxic chemotherapy. In combined phase II studies of 142 patients with CD33-positive acute myeloid leukemia in first relapse, Mylotarg monotherapy was associated with a 30% overall response rate. Although treated patients had relatively high incidences of myelosuppression, hyperbilirubinemia, and elevated hepatic transaminases, the incidences of severe mucositis and infections were low compared with what might be expected in association with conventional chemotherapeutic treatment. Preliminary data in pediatric patients also suggest that the immunoconjugate is reasonably well tolerated. Studies of Mylotarg in combination with anthracycline, cytarabine, and agents that inhibit P-glycoprotein are underway.

Acute myeloid leukemia: therapeutic indications

The main issue for younger patients with acute myeloid leukemia is the prevention of relapse. About 55% of patients relapse and the risk can partially be predicted by prognostic factors, particularly cytogenetics. A number of strategies can attempt to reduce the relapse risk. Intensification of induction therapy has been attempted but there is as yet no convincing evidence that survival is improved. Transplantation of either allogeneic or autologous stem cells does not seem to offer major survival advantage overall or within risk groups. Improved understanding of resistance mechanisms and the identification of new risk factors may enable the development of a more targeted approach to therapy.

Acute myeloid leukemia in adults

The treatment outcome for most adults with acute myeloid leukemia (AML) remains unacceptable. Additional agents or substitution of high-dose cytarabine for conventional-dose cytarabine during induction does not improve the remission rate or overall survival. There is substantial toxicity with high-dose cytarabine during induction. Thus, induction therapy for newly diagnosed patients with AML should consist of cytarabine (100 mg/m(2) as a continuous intravenous infusion over 24 hours for 7 days) and daunorubicin, idarubicin, or mitoxantrone. Meta-analysis demonstrates a modest benefit for idarubicin. Most patients who achieve a remission should receive further therapy with two to four cycles of high-dose cytarabine. Allogeneic stem cell transplant is reserved for patients with poor risk features. There is no role for autologous stem cell transplant in first remission outside a clinical trial. The majority of adults relapse. Salvage therapy usually consists of high-dose cytarabine. Allogeneic or autologous stem cell transplantation is preferred in second or subsequent remission. Uncommon diseases such as AML, for which the outcome remains poor, should be treated on clinical trials whenever possible.