Treatment of acute myeloid leukemia in elderly patients with oral idarubicin as a single agent

Mitochondrial metabolism as a target for acute myeloid leukemia treatment

Acute myeloid leukemias (AML) are a group of aggressive hematologic malignancies resulting from acquired genetic mutations in hematopoietic stem cells that affect patients of all ages. Despite decades of research, standard chemotherapy still remains ineffective for some AML subtypes and is often inappropriate for older patients or those with comorbidities. Recently, a number of studies have identified unique mitochondrial alterations that lead to metabolic vulnerabilities in AML cells that may present viable treatment targets. These include mtDNA, dependency on oxidative phosphorylation, mitochondrial metabolism, and pro-survival signaling, as well as reactive oxygen species generation and mitochondrial dynamics. Moreover, some mitochondria-targeting chemotherapeutics and their combinations with other compounds have been FDA-approved for AML treatment. Here, we review recent studies that illuminate the effects of drugs and synergistic drug combinations that target diverse biomolecules and metabolic pathways related to mitochondria and their promise in experimental studies, clinical trials, and existing chemotherapeutic regimens.

A phase I/II study of oral etoposide and idarubicin in elderly patients with high-risk acute myeloid leukemia unable to undergo intensive chemotherapy

Acute myeloid leukemia (AML) is a disease of mostly elderly patients who are often unable to undergo intensive intravenous chemotherapy. In an attempt to provide an all-oral regimen suitable for palliative treatment, we assessed the antileukemic efficacy of combination therapy of idarubicin 20 mg/m(2) (days 1, 3, and 5) and etoposide (EI) in increasing doses (75-125 mg/m(2)) on days 1-5. Eleven patients were included (median age 69 years, range: 56-77) with prognostically unfavorable characteristics (myelodysplastic syndrome, relapse, or unfavorable karyotypes). No complete remission and five partial remissions were observed whereas four patients had persistent leukemia. There were two patients who succumbed to early death. Median overall survival was 100 days (range: 8-493 days). Nonhematological toxicities were acceptable with nausea/vomiting being the predominant side effect. Hematological toxicity with grade III/IV aplasia was seen in all patients. In this study EI did not show convincing antileukemic efficacy and was unable to induce clinically useful complete remissions, with a substantial risk profile. In contrast to the situation of elderly patients with standard-risk AML in which similar oral treatment has shown promising activity, EI cannot be recommended for elderly patients with high-risk AML.

[Treatment of cancer and hematological malignancy in elderly people (Part II)]

PURPOSE

Fifty percents of cancer arise in people older than 65-year-old. Most clinical trials in cancer treatment are limited in patients younger than 65-year-old. We review literature-describing particularity of cancer treatment in elderly patients.

CURRENT KNOWLEDGE AND KEY POINTS

Therapeutic decisions should be based on an estimation of the patient's life expectancy, and risks and benefits should be weighted up accordingly. Geriatric oncology is made of a geriatric evaluation of patient and of knowledge of clinical trial about elderly patients.

FUTURE PROSPECTS AND PROJECTS

We present in this issue the principle of geriatric evaluation and the results of recent clinical trial on elderly cancer patients.

New oral drugs in older patients: a review of idarubicin in elderly patients

Idarubicin (IDA) is a structural analogue of daunorubicin with the same mechanism of action. Unlike the other currently available anthracyclines, it has a significant oral bioavailability, which makes it particularly attractive for the treatment of elderly patients. IDA resulted at least as effective as daunorubicin for acute nonlymphocytic leukemia and additional data are in analysis as far as lymphomas and breast cancer are concerned. Adverse effects are mainly hematological, while hair loss, mucositis and cardiotoxicity are less frequently reported with IDA than with other anthracyclines. The pharmacokinetics, activity, adverse effects and new modalities of oral administration are reviewed.

Acute myeloid leukemia in the elderly: biology and therapeutic strategies

Age represents one of the most important adverse prognostic factors in acute myeloid leukemia (AML). The therapeutic results for patients older than 60 years accrued into clinical trials of intensive chemotherapy are largely unsatisfactory (complete remission rates rarely superior to 50-60%; median relapse-free survival usually less than 12 months). Because only 30-40% of elderly patients are actually entered into these trials, the overall failure of current treatments appear even more disappointing when considered in the context of the whole population of older individuals with AML. This appears primarily due to intrinsic differences in the biology of leukemia itself and to host-related factors (i.e. reduced tolerance to chemotherapy and comorbidity). AMLs of older subjects display several biological overlaps with secondary AMLs including multilineage involvement, phenotype, unfavorable cytogenetics and elevated activity of multidrug resistance genes. The clinical application of biologically-based prognostic factors may enable to separate patients who may actually benefit from aggressive chemotherapy from those who should be offered attenuated/palliative treatments or enrolled upfront into experimental trials of new drugs or biologic/immunologic treatments. This may hopefully result in a 'risk-adapted' strategy aimed at improving disease free survival and/or quality of life for patients with differing risk profiles.

Oral idarubicin in patients with late chronic phase chronic myelogenous leukemia or chronic myelomonocytic leukemia

Patients with chronic myelogenous leukemia (CML) who have failed or cannot receive interferon alpha (IFN-alpha) based regimens or patients with advanced chronic myelomonocytic leukemia (CMML) have very limited current therapeutic options. Hence, there is a need to develop new strategies for these patients. This study was undertaken to determine the efficacy and toxicity of a chronic low-dose oral idarubicin regimen in these patients as positive data has been generated on this agent in shorter schedules given to patients with other hematological malignancies. Eighteen patients were treated on study. The starting dose of oral idarubicin was 2 to 5 mg/m2 daily depending in initial WBC count. This dose was escalated in the absence of Grade 4 myelosuppression or Grade 3 or 4 extramedullary toxicity. Oral idarubicin was given daily for 28 days followed by a 21 day break off treatment in repeated cycles until there was evidence of disease progression or intolerable toxicity. The dose of idarubicin was adjusted, at 2-week intervals, by 25% to maintain a white blood cell (WBC) count between 2 and 4x10(9)/L and a platelet count of >75x10(9)/L. The dose was reduced by 25% for grade 2 extramedullary toxicity and held until toxicity resolved to grade 2 or better for grade 3 toxicity. Oral idarubicin was then restarted at 75% of the initial dose. Five out of 14 CML patients achieved a complete hematologic remission. No CMML patient responded (median survival 3 months). The overall median survival was 24 months. CML patients had a median survival of 28 months. Major toxicities (myelosuppression, gastrointestinal, cardiac) were infrequent with a median cumulative dose of 1110 mg/m2 (range 54-9750). Five patients have received oral idarubicin for > 1 year with no overt cardiotoxicity, reaching median cumulative dose of 2756 mg/m2 (range 2550-9750) which is higher than those documented in prior studies. We conclude that oral idarubicin is sufficiently safe and active to warrant phase II studies investigating it as part of interferon-based regimens in patients with advanced CML.

Acute myeloid leukemia in the elderly

The optimal management of acute myeloid leukemia in patients over 60 years-of-age remains a controversial issue. The complete remission rates after conventional induction chemotherapy progressively decreases after the age of 60. This is explained by host-related factors and by differences in the biology of leukemia. The incidence of adverse prognostic factors (trilineage myelodysplasia, unfavorable karyotype, mdrl-positive phenotype) is higher in elderly patients. Three strategies are currently offered to older adults with acute myeloid leukemia: intensive chemotherapy, palliative treatment and attenuated dose chemotherapy. Currently, complete remission rates achieved with conventional chemotherapy range from 40-65% according to inclusion criteria. In the past few years, two approaches have been tested in order to improve the results of induction chemotherapy: modifications of chemotherapy regimens with new intercalating agents (idarubicin, mitoxantrone) and the use of myeloid growth factors. Myeloid growth factors have been administered with two objectives: to reduce the duration of neutropenia and the toxic death rate when given after induction chemotherapy, and to prime leukemic blasts when given during chemotherapy. The results of published placebo-controlled studies are discussed. The issues of palliative treatment and of attenuated dose chemotherapy are also addressed in the review, with special emphasis on the role of oral idarubicin.

Results of conventional-dose cytosine arabinoside and idarubicin in elderly patients with acute myeloid leukemia

Conventional-dose Ara-C (200 mg/m2 d 1-5) combined with idarubicin (12 mg/m2 d 1-3) was employed as remission induction and consolidation therapy in 23 elderly AML patients with a median age of 66 years (range, 60-75) with AML according to the FAB criteria (M1 n = 3, M2 n = 10, M4 n = 6, M5 n = 2, M6 n = 2), eligible for the study. In seven patients earlier MDS had been documented by previous bone marrow aspirates. The CR rate after one induction course was 65% (15/23). Toxicity was acceptable, with four patients dying during the chemotherapy-induced hypoplasia (4/23). Although 80% of the CR patients received two additional cycles of Ara-C and idarubicin as consolidation therapy, only two patients are still in continuous complete remission more than 12 months after achieving CR. The median disease-free survival of the CR patients was 11.5 months and the median survival of the entire group was 10 months. We conclude that conventional dose Ara-C/idarubicin is an effective protocol for inducing complete remission in elderly patients with AML, but that consolidation therapy consisting of two courses of the same regimen does not produce a relevant rate of long-term disease-free survival.

Acute myeloid leukemia in patients more than 50 years of age: special considerations in diagnosis, treatment, and prognosis

Although most patients with acute myeloid leukemia are more than 50 years of age and age is known to be an adverse prognostic factor, relatively few studies have been conducted to determine the optimum treatment strategy for the older patient. This report suggests that, until definitive studies are conducted in this age group, intensive chemotherapy should always be considered if the older patient's overall status and desires are consistent with this approach. Other factors, specifically cytogenetic and cell-surface marker findings, provide prognostic information, independent of age, and should also be considered during patient management.

Cancer in the elderly

This article reviews geriatric oncology and assesses options for treatment and care of the elderly patient with cancer. The size of the population over 65 years old is defined, with particular reference to the continuing growth of this subsection of the community. The high incidence of many cancers and their associated mortality rates in the elderly are identified and the epidemiology of such diseases in the geriatric population is addressed. Given the discrepancies in incidence and survival rates between patients younger and older than 65 years, the association between tumorigenesis and the aging process is explored. Specific aspects of tumor growth in the elderly are considered. General considerations of therapy for elderly patients with cancer are discussed, including the pharmacokinetics and pharmacodynamics of chemotherapy in those over 65 years old, surgical options, the use of radiotherapy, and overall patient assessment. Next, treatment options for individual cancer states are reviewed, with particular emphasis on newer treatment options designed specifically for the elderly. Sections on cancer screening and supportive care are also included, the latter dealing with aspects of symptom control, quality of life assessment, and the physical and psychologic rehabilitation of the elderly patient with cancer who is undergoing treatment. Conclusions are then drawn as to the extent of the oncological process in those over 65 years old, with particular emphasis on the underdiagnosis and undertreatment of many malignancies in the past. The challenge created by the growing elderly population is underscored and necessary plans of action for oncologists in the future are defined. Such proposals are necessary if inroads are to be made into the unacceptable morbidity and mortality rates borne by our elderly patients with cancer.

Treatment of myelodysplastic syndromes with daily oral idarubicin. A phase I-II study

BACKGROUND

Idarubicin, a new anthracycline analogue, is available in an oral preparation, and responses have been observed using relatively aggressive therapy in patients with myelodysplastic syndromes (MDS). The authors studied whether a chronic low-dose schedule would be effective but less myelotoxic.

METHODS

Forty-two patients with MDS received daily low-dose oral idarubicin in 5-week courses that included 3 weeks of treatment, followed by a 2-week rest period. Doses were escalated when possible after the second course, and each patient was to receive six courses.

RESULTS

Only one partial response was observed. Although no patient had fatal bone marrow toxicity, only eight patients received the full six courses, primarily because of myelosuppression.

CONCLUSIONS

This schedule of oral idarubicin is relatively safe but produces fewer responses than are reported with the high-dose pulse regimens.

Oral idarubicin--an anthracycline derivative with unique properties

Idarubicin belongs to a group of anthracyclines in which the methoxyl group in position 4 of the D ring in the aglycone moiety is replaced by a hydrogen atom. Lipophilicity is increased compared with other anthracyclines; as a result, idarubicin is the first anthracycline that can be administered orally while at the same time retaining its antitumor activity. In addition, the lipophilicity enables the transition of the substance, especially of the metabolite, to the cerebrospinal fluid. The metabolite idarubicinol is formed in high concentrations; this is particularly true with oral administration. Compared with all other anthracyclines, it has a very long half-life. It is the first anthracycline metabolite to have the same cytotoxic activity as the parent compound. The cardiotoxicity of idarubicin, being lower than that of other anthracyclines at equally effective doses, is even more reduced with oral administration. Preclinical and clinical experiences with oral idarubicin are reviewed.

Idarubicin: a second-generation anthracycline

Because of its in vitro activity in leukemic cell lines and Phase I studies of acute leukemia, Phase II and III clinical trials with idarubicin hydrochloride were conducted in patients with acute lymphocytic leukemia or acute nonlymphocytic leukemia. In the Phase III comparative trials between the combinations of idarubicin and cytarabine and daunorubicin hydrochloride and cytarabine, the idarubicin/cytarabine combination resulted in significantly greater complete remission rates and longer overall survival in two of three studies conducted in the US. As a result, the Food and Drug Administration approved intravenous idarubicin with a Class 1A rating in September 1990 for use in combination with other antileukemic drugs (e.g., cytarabine) for the treatment of acute myelogenous leukemia in adults. The recommended dose of idarubicin is 12 mg/m2 daily for three days by slow intravenous injection in combination with cytarabine. Although idarubicin causes myelosuppression similar to that described with daunorubicin, the incidence of cardiotoxicity in animal models is lower. Idarubicin also has the advantage of oral administration, but the oral formulation of the drug remains investigational. The use of idarubicin in pediatric patients also remains to be established.

Etoposide, 6-thioguanine and idarubicin, an oral combination regimen (ETI) for the induction treatment of acute leukemia

Twenty patients with advanced acute leukemia (16 acute myeloid leukemia (AML), three myeloid blast crisis (BC) of chronic myeloid leukemia (CML), one acute lymphatic leukemia) were treated with a peroral regimen consisting of etoposide 80 mg/m2 and 6-thioguanine 100 mg/m2 twice daily for 5 days, and idarubicin 15 mg/m2 once daily for 3 days (ETI). Two AML patients were in first relapse. All the other patients with acute leukemia had a later relapse or were refractory to primary or salvage treatment. One to six ETI cycles were given. Four AML patients achieved remission and one patient with BC of CML entered the second chronic phase. Clearing of the blood of leukemic cells was seen in seven additional patients. Infection was the most common complication, gastrointestinal toxicity was not a major problem. In conclusion, peroral ETI treatment has a marked antileukemic effect even in an advanced disease, and the toxicity is moderate and well acceptable.