Mitoxantrone and etoposide: an effective regimen for refractory or relapsed acute myelogenous leukemia

Deciphering molecular mechanisms underlying chemoresistance in relapsed AML patients: towards precision medicine overcoming drug resistance

Background

Acute myeloid leukemia (AML) remains a devastating disease with a 5-year survival rate of less than 30%. AML treatment has undergone significant changes in recent years, incorporating novel targeted therapies along with improvements in allogeneic bone marrow transplantation techniques. However, the standard of care remains cytarabine and anthracyclines, and the primary hindrance towards curative treatment is the frequent emergence of intrinsic and acquired anticancer drug resistance. In this respect, patients presenting with chemoresistant AML face dismal prognosis even with most advanced therapies. Herein, we aimed to explore the potential implementation of the characterization of chemoresistance mechanisms in individual AML patients towards efficacious personalized medicine.

Methods

Towards the identification of tailored treatments for individual patients, we herein present the cases of relapsed AML patients, and compare them to patients displaying durable remissions following the same chemotherapeutic induction treatment. We quantified the expression levels of specific genes mediating drug transport and metabolism, nucleotide biosynthesis, and apoptosis, in order to decipher the molecular mechanisms underlying intrinsic and/or acquired chemoresistance modalities in relapsed patients. This was achieved by real-time PCR using patient cDNA, and could be readily implemented in the clinical setting.

Results

This analysis revealed pre-existing differences in gene expression levels between the relapsed patients and patients with lasting remissions, as well as drug-induced alterations at different relapse stages compared to diagnosis. Each of the relapsed patients displayed unique chemoresistance mechanisms following similar treatment protocols, which could have been missed in a large study aimed at identifying common drug resistance determinants.

Conclusions

Our findings emphasize the need for standardized evaluation of key drug transport and metabolism genes as an integral component of routine AML management, thereby allowing for the selection of treatments of choice for individual patients. This approach could facilitate the design of efficacious personalized treatment regimens, thereby reducing relapse rates of therapy refractory disease.

Considerations and challenges for patients with refractory and relapsed acute myeloid leukaemia

Despite advances in understanding the complexities of acute myeloid leukaemia (AML), the treatment of refractory or relapsed AML (rrAML) remains a daunting clinical challenge. Numerous clinical trials have failed to identify new treatments or combinations of existing therapies that substantially improve outcomes and survival. This may be due, at least in part, to heterogeneity among study patients with respect to multiple inter-related factors that have been shown to affect treatment outcomes for patients with rrAML; such factors include age, cytogenetics, immunophenotypic changes, and (in the case of relapsed AML) duration of first complete remission, or if the patient has had a previous blood and marrow transplant (BMT). A clear understanding of disease characteristics and patient-related factors that influence treatment response, as well as expected outcomes with existing and emerging therapies, can aid clinicians in helping their patients navigate through this complex disease state.

Mitoxantrone and Etoposide for the Treatment of Acute Myeloid Leukemia Patients in First Relapse

Relapsed acute myeloid leukemia (AML) represents a major therapeutic challenge. Achieving complete remission (CR) with salvage chemotherapy is the first goal of therapy for relapsed AML. However, there is no standard salvage chemotherapy. The current study evaluated outcomes and prognostic factors for achievement of CR in 91 AML patients in first relapse who were treated with the mitoxantrone-etoposide combination regimen. The overall response rate (CR and CRi) was 25%. Factors that were associated with a lower rate of CR included older age, shorter duration of first CR, low hemoglobin, and low platelet count. The median overall survival for all patients was 7.4 months. The survival of patients who achieved CR and underwent allogeneic hematopoietic cell transplantation (allo-HCT) was higher than those who achieved CR and did not undergo allo-HCT (35.3 months vs. 16.8 months, p = 0.057). The median duration of relapse-free survival was 12.7 months in the patients achieving CR. Older age at the time of AML relapse was associated with worse overall survival. The all-cause 4-week mortality rate was 4%, and the all-cause 8-week mortality rate was 13%. The findings of this study underscore the need for newer therapies, especially those that will improve the ability for patients with relapsed AML to achieve CR and to allow them to receive additional therapies.

Inferior outcome after allogeneic transplant in first remission in high-risk AML patients who required more than two cycles of induction therapy

While some patients with high-risk acute myeloid leukemia (AML) require one or two cycles of induction chemotherapy to achieve a complete remission (CR), others require more than two cycles. We examined the outcomes of patients with high-risk AML who received allogeneic HPC transplant in CR1. Forty five consecutive high-risk AML patients in CR1 were included. All 45 patients had adverse cytogenetics, FLT 3 mutations, or secondary AML. Group A patients (n = 33) received one or two cycles, and Group B (n = 12) three or more cycles of induction chemotherapy. The patients were comparable in age, sex, white cell count at presentation, and time from diagnosis and from last chemotherapy to transplant. The 100-day mortality rate was higher in Group B patients (50% vs. 9%, P = 0.006). They had a higher non-relapse mortality (33% vs. 6%, P = 0.035) and a longer length of hospital stay from the day of stem cell infusion (median 21 vs. 20, P = 0.02; third quartile 22 vs. 28, P = 0.02). There was also a trend toward inferior event-free survival and overall survival. High-risk AML patients undergoing allogeneic transplant in CR1 after three or more cycles of induction chemotherapy have an inferior outcome and higher mortality when compared to those who only needed one or two cycles of induction chemotherapy. Novel strategies are needed to reduce the transplant-related mortality in high-risk AML patients needing more than two cycles of induction chemotherapy prior to allogeneic transplant in CR1.

Relapsed and refractory pediatric acute myeloid leukemia: current and emerging treatments

Survival rates for children with acute myeloid leukemia (AML) exceed 60 % when modern, intensified chemotherapeutic regimens and enhanced supportive care measures are employed. Despite well-recognized improvements in outcomes, primary refractory or relapsed pediatric AML yields significant morbidity and mortality, and improved understanding of this obstinate population along with refined treatment protocols are urgently needed. Although a significant number of patients with refractory or relapsed disease will achieve remission, long-term survival rates remain poor, and efforts to identify therapies which will improve OS are under continuous investigation. The current fundamental goal of such investigation is the achievement of as complete a remission as possible without dose-limiting toxicities, and the progression to hematopoietic stem cell transplantation thereafter. In this review the scope of the problem of relapsed and refractory AML as well as current and emerging chemotherapy options will be discussed.

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.

A randomized trial of liposomal daunorubicin and cytarabine versus liposomal daunorubicin and topotecan with or without thalidomide as initial therapy for patients with poor prognosis acute myelogenous leukemia or myelodysplastic syndrome

BACKGROUND

Because angiogenesis may play a role in the pathogenesis of acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS), and thalidomide (Th) has shown significant anti-angiogenic activity, this study was designed to investigate the potential role of Th in the treatment of patients with AML and MDS and the possible role of a non-ara-C-containing regimen.

METHODS

Adults with AML or high-risk MDS and cytogenetic abnormalities other than inv (16), t(8;21), -Y or -X were randomized to receive liposomal daunorubicin (DNX) and ara-C (DA) or DNX and topotecan (DT). Within each arm, patients were randomized to receive chemotherapy alone (DA or DT) or with thalidomide (DATh or DTTh). Vascular endothelial growth factor (VEGF) plasma levels and microvascular density was measured before and after therapy. Eighty-four patients (median age, 65 years; range, 27-84 years) were treated.

RESULTS

None of 11 patients treated with DT or DTTh responded and these arms were closed. Seventeen of 37 patients treated with DA and 15 of 36 treated with DATh achieved an early complete remission. Median complete response duration was 38 and 34 weeks (P = 0.57) and median survival 35 and 28 weeks (P = 0.15), respectively. Patients with high pretreatment VEGF levels had an inferior survival. There was no significant difference in the changes in VEGF levels or microvascular density after treatment in patients who did versus those who did not receive thalidomide.

CONCLUSIONS

The authors concluded that thalidomide in combination with chemotherapy does not result in clinical benefit in patients with AML or high-risk MDS.

MEC (mitoxantrone, etoposide and intermediate dose cytarabine): an effective induction regimen for previously untreated acute non-lymphocytic leukemia

Twenty-three patients with acute non lymphocytic leukemia (ANLL), were treated with a single-6 day course of Mitoxantrone 6mg/m2/day, Etoposide 80mg/m2/day and intermediate dose Cytarabine (ara-C) 1g/m2/day (MEC). Patients who achieved complete remission (CR) were submitted to a 4-day-course of MEC as consolidation. Seventeen patients (73.9%) obtained CR, five patients (22.7%) were resistant to the treatment and one patient died during induction. Median remission duration was 11 months; overall median survival was 16 months. Relapses occurred in 11 patients; eight patients are still alive: 6 in 1st, 2 in 2nd CR (mean survival 20.1 months, range 17-26). All patients experienced severe myelosuppression comparable to that observed after classical induction cycles including ara-C in continuous intravenous infusion; none, however, died of infection. Non-hematologic toxicity was minimal; in particular, neurotoxicity was not observed. According to our results, the MEC regimen, which was previously demonstrated to be active in refractory patients, represents an effective induction treatment in ANLL, with an acceptable toxicity.

Combination of mitoxantrone and etoposide in the treatment of myelodysplastic syndromes transformed into acute myeloid leukemia

Mitoxantrone and etoposide have both been shown to be effective in de novo acute myeloid leukemia. Therefore, the combination of mitoxantrone and etoposide, the NOVE regimen, was examined in the treatment of myelodysplastic syndromes (MDS) transformed into acute myeloid leukemia (AML). Twenty-one previously untreated patients (eight females, thirteen males) with a median age of 56 years (range 28-67 years) were studied. Diagnosis of MDS was made within the range of six months to three years before transformation into AML occurred. The NOVE regimen consisted of mitoxantrone 10 mg/m2 day 1-5, and of etoposide 100 mg/m2 day 1-5. After one single course of therapy eleven patients achieved a complete remission (CR) and three patients a partial remission (PR). Nine patients (six in CR and three in PR) received a second course, and the PR was completed to a CR in one patient. Thus, the overall response rate was 66% (14/21 patients), and the CR rate was 57% (12/21 patients). Median duration of CR was 7 months (range 2-10 months). Median survival was 10 months (range 3-20 months) for complete responders and 3 months (range 1-10 months) for patients who did not achieve a CR. For patients with subsequent CR, median time of granulocytopenia (< 500/microliters) and thrombocytopenia (< 20.000/microliters) was 20 days and 18 days, respectively. In conclusion, the NOVE regimen appears to be effective in AML secondary to MDS. However, strategies for remission maintenance are warranted.

Treatment of refractory and relapsed adult acute leukemia using a uniform chemotherapy protocol

Twenty-nine adult patients with relapsed (21) or refractory (8) de novo acute leukemia (12 ALL and 17 ANLL) were treated with a remission-induction salvage chemotherapeutic protocol including vindesine, mitoxantrone, cyclophosphamide, intermediate-dose cytosine arabinoside, prednisolone and methotrexate. Ten of seventeen (59%) ANLL and 8/12 ALL (67%) achieved complete remission (CR). Seven of eight (86%) cases refractory to first-line remission-induction therapy (3/4 ANLL and 4/4 ALL) entered complete remission. The most frequent non-hematologic side effects were gastrointestinal. All patients experienced severe pancytopenia, with median times to recovery of granulocyte and platelet counts of 28 and 29 days, respectively. Nine of twenty-nine (31%) patients suffered febrile episodes of unknown origin and 13/29 (45%) suffered documented infections. Five patients (17%) died while aplastic, four from infection and one from cardiotoxicity. Four patients who entered CR were submitted to a bone marrow transplantation (BMT), two autologous and two allogeneic BMT. Sixteen of the 18 patients who entered CR relapsed, with a median remission duration of 3.5 +/- 2.9 months. Two patients remain in remission at 5+ and 17+ months. These results suggest that this protocol is an effective remission-induction salvage therapy for adult acute leukemias.

In vitro testing of chemotherapeutic drug combinations in acute myelocytic leukaemia using the fluorometric microculture cytotoxicity assay (FMCA)

The fluorometric microculture cytotoxicity assay (FMCA) was employed for analysing the effect of different chemotherapeutic drug combinations and their single constituents in 44 cases of acute myelocytic leukaemia (AML). A large heterogeneity with respect to cell kill was observed for all combinations tested, the interactions ranging from antagonistic to synergistic in terms of the multiplicative concept for drug interactions. However, an 'additive' model provided a significantly better fit of the data compared to the effect of the most active single agent of the combination (Dmax) for several common antileukaemic drug combinations. When the two interaction models were related to treatment outcome 38% of the non-responders showed preference for the additive model whereas the corresponding figure for responders was 80%. Overall, in 248 of 290 (85%) tests performed with drug combinations, there was an agreement between the effect of the combination and that of the most active single component. Direct comparison of Dmax and the combination for correlation with clinical outcome demonstrated only minor differences in the ability to predict drug resistance. The results show that FMCA appear to report drug interactions in samples from patients with AML in accordance with clinical experience. Furthermore, testing single agents as a substitute for drug combinations may be adequate for detection of clinical drug resistance to combination therapy in AML.

Mitoxantrone and high-dose etoposide for patients with relapsed or refractory acute leukemia

Among 35 patients with relapsed or refractory acute myelogenous leukemia (AML) who received salvage chemotherapy, 28 were treated with mitoxantrone (7.5 mg/m2/d intravenously [IV] over 1 hour for 5 days) and etoposide (VP-16) (2 g/m2 over 4 days either as a daily infusion or as two daily doses). Seven patients received mitoxantrone (6 mg/m2/d for 5 days) and VP-16 (1500 mg/m2 over 3 days). The median duration of the initial complete remission (CR) was 6 months and 83% of the patients had initial CR that lasted 12 months or less. Forty-six percent of the patients were undergoing a second or subsequent salvage attempt. Eight patients (23%) achieved CR; seven of these CR were obtained after one course of therapy. Twelve patients (33%) died and 15 patients (42%) had disease that was resistant to treatment. Patients undergoing a first salvage attempt had a higher incidence rate of CR than those undergoing a second or subsequent salvage attempt (37% versus 6%; P = 0.03). CR rates were also higher in patients with a favorable (translocation 8;21 or 15;17) or diploid karyotype compared with other patients (32% versus 8%; P = 0.10). The median survival time was 2 months for all patients and 8 months for patients achieving CR. Mucositis occurred in 74% of the patients and was severe in 32%. Diarrhea and rash occurred in less than 33% of the patients. Fever was noticed in all but 1 of the patients and documented infections occurred in 65% of the patients. Six patients had pancytopenia or thrombocytopenia that lasted more than 42 days from the initiation of treatment. Although mitoxantrone and high-dose VP-16 is an effective antileukemic regimen, it is associated with a high incidence of mucositis. Strategies that are used to limit mucosal damage may improve the tolerance of this combination.

Mitoxantrone. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in the chemotherapy of cancer

Mitoxantrone is a dihydroxyanthracenedione derivative which as intravenous mono- and combination therapy has demonstrated therapeutic efficacy similar to that of standard induction and salvage treatment regimens in advanced breast cancer, non-Hodgkin's lymphoma, acute nonlymphoblastic leukaemia and chronic myelogenous leukaemia in blast crisis; it appears to be an effective alternative to the anthracycline component of standard treatment regimens in these indications. Mitoxantrone is also effective as a component of predominantly palliative treatment regimens for hepatic and advanced ovarian carcinoma. Limited studies suggest useful therapeutic activity in multiple myeloma and acute lymphoblastic leukaemia. Regional therapy of malignant effusions, hepatic and ovarian carcinomas has also been very effective, with a reduction in systemic adverse effects. Mitoxantrone inhibits DNA synthesis by intercalating DNA, inducing DNA strand breaks, and causing DNA aggregation and compaction, and delays cell cycle progression, particularly in late S phase. In vitro antitumour activity is concentration- and exposure time-proportional, and synergy with other antineoplastic drugs has been demonstrated in murine tumour models. Leucopenia may be dose-limiting in patients with solid tumours, whereas stomatitis may be dose-limiting in patients with leukaemia. Other adverse effects are usually of mild or moderate severity although cardiac effects, particularly congestive heart failure, may be of concern, especially in patients with a history of anthracycline therapy, mediastinal irradiation or cardiovascular disease. Mitoxantrone displays an improved tolerability profile compared with doxorubicin and other anthracyclines, although myelosuppression may occur more frequently. Thus, mitoxantrone is an effective and better tolerated alternative to the anthracyclines in most haematological malignancies, in breast cancer and in advanced hepatic or ovarian carcinoma. Further studies may consolidate its role in the treatment of these and other malignancies.