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 ≤14 months and overall median survival was ≤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.     

Duration of second complete remission compared with first complete remission in patients with acute myeloid leukemia. Eastern Cooperative Oncology Group.

The prognosis for patients with acute myeloid leukemia in first relapse is generally poor. The ability to induce a second complete remission (CR) with the same chemotherapy used in initial induction therapy is limited. Remission inversion rate, defined as achieving a longer second CR than the first CR in response to standard chemotherapy for relapse, is important in assessing studies of novel chemotherapy or immunologic treatment strategies for patients with relapsed disease. One hundred and twenty-four patients entered on two Eastern Cooperative Oncology Group (ECOG) studies for patients with relapsed AML were analyzed to determine the remission inversion rate. Twenty-two of the 124 patients (18%; 95% confidence interval 12-26%) experienced a longer second CR duration than the first CR duration by at least 2 months. Inversion of CR duration is thus not a rare event. The inversion frequency reported here establishes a baseline upon which future studies in relapsed disease need to be defined.     

Clonal evolution detected with conventional cytogenetic analysis is a potent prognostic factor in adult patients with relapsed AML

We retrospectively investigated 144 patients with relapsed acute myeloid leukemia (AML) to clarify predisposing factors and the prognostic impact of acquisition of additional cytogenetic abnormalities (ACA) at the first relapse. Additional cytogenetic abnormalities are recognized as clonal evolution at the cytogenetic level. Fifty‐nine patients (41%) acquired ACA at the first relapse. The incidences of ACA acquisition varied depending on cytogenetic abnormalities at initial diagnosis. Multivariate analysis identified t(8;21), complex karyotype, and a duration of fewer than 12 months of complete remission as independent predisposing factors for ACA acquisition. Notably, patients with ACA acquisition showed a significantly lower second complete remission rate compared with those without ACA acquisition (20.0% vs 72.5%, respectively, P < .001). Furthermore, the 3‐year overall survival rates after the first relapse were significantly different between patients with and without ACA acquisition (8.5% vs 36.8%, respectively, P < .001). This prognostic significance was confirmed with multivariate analysis. The hazard ratio of ACA acquisition was similar or higher than reported prognostic factors for relapsed AML patients. These findings suggested that clonal evolution detected with conventional cytogenetic analysis at the first relapse induces severe chemo‐refractory characteristics in AML cells and should be considered as a potent prognostic factor when evaluating accurate prognosis in relapsed AML patients.     

Arsenic trioxide (trisenox) therapy for acute promyelocytic leukemia in the setting of hematopoietic stem cell transplantation

The relapse-free survival of patients with acute promyelocytic leukemia (APL) has significantly increased during the last decade. The introduction of all-trans retinoic acid (ATRA) doubled the survival of patients with this disease. However, despite ATRA and anthracycline-based chemotherapy, 12%-30% of patients will still relapse. Arsenic trioxide (ATO) has demonstrated efficacy and safety in patients with first and subsequent relapsed or refractory APL, regardless of the disease-free interval. Treatment of relapsed and refractory patients with this novel therapy produces complete remission in 87% of patients and molecular remission in 83%. Studies have documented the efficacy of autologous and allogeneic transplantation as salvage therapy in relapsed and refractory APL. The introduction of ATO into the treatment regimen for APL has stimulated discussion on its role in the transplantation setting. Investigators recently met to discuss the issue and make recommendations regarding ATO therapy in patients who are in their second or subsequent complete remission and are candidates for transplantation. This article describes the pivotal studies of this novel agent, discusses risk factor stratification for relapse in patients with APL, and proposes protocols for treatment incorporating ATO therapy. In addition, it describes scientific issues in ongoing and proposed clinical trials of ATO therapy for this disease.     

Definition of refractoriness against conventional chemotherapy in acute myeloid leukemia: a proposal based on the results of retreatment by thioguanine, cytosine arabinoside, and daunorubicin (TAD 9) in 150 patients with relapse after standardized first line therapy

Response to salvage therapy at first and second relapse was analyzed in 150 patients with acute myeloid leukemia (AML) to improve the characterization of relapsed AML and to deduce from this analysis a proposal for the definition of refractoriness against conventional therapy. Salvage treatment consisted of a repetition of the TAD 9 regimen which was already applied as induction protocol at initial diagnosis. All patients were recruited from the multicenter 1982 trial of the German AML Cooperative Group and had thus received a standardized first line treatment. Response at first relapse was significantly related to the duration of the first remission. From 38 patients relapsing within 6 months after successful induction therapy, only 11 (28%) achieved a second complete remission as compared to 58 of 98 (59%) cases with later occurring relapses (p less than 0.01). This difference was due to a significantly higher incidence of persistent leukemia in the former group and not biased by differences in early death rates. No other variable was found predictive for the response to salvage treatment including age, WBC, serum LDH, morphologic subtype, presence or absence of DNA aneuploidy as detected by flow cytometry or maintenance chemotherapy. A low remission rate of 28% was also obtained in the 14 patients at second relapse. These data indicate that patients with a duration of their first remission of more than 6 months cannot be considered as being refractory against standard chemotherapy while patients with early relapses and second recurrences have a response rate of less than 30% due to refractory disease. Hence, the following criteria are proposed for the definition of refractoriness against standard chemotherapy in advanced AML: (a) nonresponse to first-line induction therapy, (b) early relapse within 6 to 12 months of first remission, (c) relapse after 6 to 12 months of first remission and failure on a reinduction attempt with established regimens, (d) second and subsequent relapses. These criteria may provide a useful rationale for the selection of the most appropriate treatment at relapse. They may also serve as eligibility criteria for clinical phase I/II studies and will facilitate interstudy comparisons.     

Treatment of relapsed acute promyelocytic leukemia

By all-trans retinoic acid (ATRA) and chemotherapy over 70% of patients with newly diagnosed acute promyelocytic leukemia (APL) may be cured; 20-30% of patients still relapse and require salvage therapy. For relapsed or refractory APL, a standard treatment has not yet been defined. However, several effective drugs and approaches have been described. Treatment options for relapsed APL include chemotherapy regimens used in the treatment of relapsed acute myeloid leukemia usually combined with ATRA or of other differentiating agents such as liposomal ATRA or synthetic retinoids. Presently, allogeneic peripheral stem cell or bone marrow transplantation is the treatment of choice for younger patients who have a histocompatible donor, as it gives the chance of cure in second or further relapse. For patients without a donor or for those who are not suitable for allogeneic transplantation, autologous stem cell or bone marrow transplantation may offer at least the possibility of a prolongation of remission, if the harvested cells are negative in the RT-PCR of PML/RAR alpha. Arsenic compounds have a high antileukemic effectiveness on APL cells. Arsenic trioxide has recently been approved for relapsed or refractory APL. With this drug, complete hematologic remission rates of 80-92% and long-lasting molecular remissions were achieved in relapsed patients. For patients who do not qualify for these treatment options, monoclonal anti-CD33 antibodies may represent further treatment options.     

All-transretinoic acid and chemotherapy in the treatment of acute promyelocytic leukemia

BACKGROUND: All-transretinoic acid (ATRA) and chemotherapy has improved complete remission rates and disease free survival in acute promyelocytic leukemia (APL). There is scanty data from Middle East. AIM: To determine the efficacy of ATRA and multi-agent combination chemotherapy in treatment of APL in a single Centre in Kuwait. SET-UPS AND DESIGN: Tertiary cancer centre, retrospective study. METHODS AND MATERIAL: All newly diagnosed APL patients were treated with oral ATRA 45 mg/m2 daily until complete remission (CR), intravenous daunorubicin 50 mg/m2 on days 1,3 and 5, cytosine arabinoside 100 mg/m2 12 hrly on days 1 through 10 and etoposide 100 mg/m2 on days 1 through 5. Post remission three courses of intensive consolidation chemotherapy were administered. Since October 1999, maintenance chemotherapy consisting of oral 6 mercaptopurine 9 mg/m2 daily, methotrexate 15 mg/m2 weekly and ATRA 45 mg/m2 for 2 weeks every three months was added. Complete remission rates and duration, relapse rate and toxicity were studied. RESULTS: 22 of 24 evaluable patients (91.6%) achieved CR. The median duration of remission was 13 months (range 2-55 months). Three patients (12.5%) relapsed. Two patients (8.3%) developed retinoic acid syndrome and responded to dexamethasone. Five patients (20.8%) died one each of refractory disease, during remission induction and of relapse. Two patients died while in remission. CONCLUSION: ATRA and combination chemotherapy results in high complete remission rates and low relapse rate in newly diagnosed APL. Maintenance therapy may be useful in preventing relapses.     

Relapsed Childhood Acute Myeloid Leukemia: Experience from a Single Tertiary Center in Thailand

Background: Few studies have examined survival outcomes in relapsed childhood acute myeloid leukemia (AML) in resource-limited countries. This study aimed to evaluate the prognostic factors and survival outcomes of relapsed childhood AML in Thailand. Methods: The medical records of AML patients aged 0-15 years treated in a major tertiary center in Southern Thailand between December 1979 and December 2019 were reviewed retrospectively. The overall survival (OS) was calculated using the Kaplan-Meier method. Results: A total of 316 AML patients were included and relapse occurred in 98 (31%) patients. Of these, 57 (58.2%) and 41 (41.8%) patients had early [≤1 year from first complete remission (CR1)] and late (>1 year from CR1) relapses, respectively. Only 54 (55.1%) patients received chemotherapy after relapse. The 3-year OS of all relapsed patients was 3.5%. The 3-year OS of patients with early and late relapse were 0% and 8.5%, respectively (p=0.002). The 3-year OS of patients who received chemotherapy and those who did not were 6.5% and 0%, respectively (p <0.0001). The median survival time of patients who did not receive chemotherapy was 1.7 months. The 3-year OS of patients who achieved second complete remission (CR2) and those who did not were 12.6% and 0%, respectively (p <0.001). Conclusion: The relapsed AML rate was 31% and the survival outcome was poor with a 3-year OS of 3.5%. The adverse prognostic factors were early relapse, failure to achieve CR2 and those who did not receive chemotherapy after relapse.     

Traitement des leucémies aiguës promyélocytaires de l’adulte

Acute promyelocytic leukaemia (APL) accounts for approximately 8% of all acute myeloid leukemias (AML) in adults. APL is characterized by a t(15;17) chromosomal translocation, a strong tendency for bleeding at diagnosis, and a sensitivity to those agents that induce a differentiation of leukaemia blasts such as all-trans retinoic acid (ATRA) or arsenic. Combined ATRA and chemotherapy have significantly improved patient outcome, with a rate of relapse that has been reduced to approximately 15%. Today, arsenic is being used successfully to treat relapsed patients; its high efficacy allows undertaking haematopoietic stem cell transplantation and achieving second full remission. Other new agents also exhibit high efficacy in APL, which makes this type of AML, considered fearsome for long, a subset for which there are a lot of therapeutic options and satisfactory therapeutic outcome.     

Treatment of acute promyelocytic leukemia in the very elderly: case report and review of the literature

Acute promyelocytic leukemia (APL) is the most curable subtype of AML yet it is not known to what extent newer therapies will succeed in the very elderly. Conventional chemotherapeutic induction regimens are usually too toxic for older patients, however, all trans-retinoic acid (ATRA) and arsenic trioxide (ATO) may be useful therapeutic options if used judiciously. This case series describes three octogenarians with APL all treated with ATRA and achieved complete remissions. The last patient received ATO at the time of first relapse and achieved a second remission. To our knowledge, this is the first report of successful use of ATO for induction in an octogenarian with APL.     

Prognostic factors in adult patients with acute leukemia at first relapse

The case histories of 252 adolescent and adult patients with acute leukemia diagnosed and treated between 1975 and 1985 are analyzed with special attention to prognostic factors determining the second complete remission (CR) rate. A first CR was achieved in 65% of cases, 60% for acute myelogenous leukemia (AML), and 75% for lymphoblastic leukemia (ALL). In 86 patients a relapse occurred (50 AML, 36 ALL), and 50% of them entered a second CR after reinduction therapy. Median survival after first relapse of these reinduction-responders was significantly prolonged in comparison to the reinduction-nonresponders for both AML (15 versus 2 months) and ALL (11 versus 3 months). Median duration of the first CR of the reinduction-responders was significantly longer than that of the second CR (13 versus 6 months). The major determinant for the probability to obtain a second CR after reinduction therapy was the duration of the first CR. The latter was significantly longer in the reinduction-responders than in the nonresponding group (13 versus 5 months). Furthermore patients younger than 40 years, and those who relapsed after ending the maintenance therapy, tended to have better chances to achieve a second CR. Rapid achievement of the first CR, and sex of the patients seemed not to be of predictive value. The authors conclude that aiming for a second CR is worthwhile in young patients who relapse after a long first CR.     

Salvage Therapy Outcomes in a Historical Cohort of Patients With Relapsed or Refractory Acute Myeloid Leukemia

BackgroundThe prognosis of patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) is poor, with no universal standard salvage therapy currently available for most patients. Novel therapies with efficacy in patient subsets often have limited activity in alternative subsets, resulting in a majority of patients not gaining benefit from these therapies. This study systematically evaluated patient outcomes in a large cohort of R/R AML patients from a single institution across all salvage therapy lines, up to and including the third line.Patients and MethodsOutcomes of R/R AML patients treated at a single institution (MD Anderson Cancer Center, Houston, TX) between 2002 and 2016 were entered into a central database. Eligible patients received one or more lines of salvage therapy after first occurrence of R/R AML. Patients who received second- or third-line salvage treatment were also included in the first salvage analysis. Eligible patients were ≥ 18 years old at time of initial AML diagnosis, with no central nervous system involvement.ResultsA total of 818 eligible patients received one or more lines of salvage therapy, 809 received second-line salvage therapy, and 397 received third-line salvage therapy. Complete remission rates decreased from 14% after first salvage therapy to 9% after second salvage therapy and 3% after third salvage therapy. Median overall survival was 6.30, 4.07, and 2.98 months after first, second, and third salvage therapies, respectively.ConclusionThese data indicate that the best chance of obtaining long-term remission in AML is with a successful first induction. Strategies that improve initial response and decrease the likelihood of relapse should be pursued.     

Advances in therapies for acute promyelocytic leukemia

Acute promyelocytic leukemia (APL), a distinct subtype of acute myelogenous leukemia (AML), results from the arrest of the maturation of hematopoietic progenitors at the promyelocyte stage. It has been shown that APL is associated with a reciprocal chromosomal translocation, involving chromosomes 15 and 17, which fuses the gene encoding the retinoic acid receptor α (RARα) and the promyelocytic leukemia (PML) gene. The resultant PML-RARα fusion protein plays a critical role in the pathogenesis of APL. Although there are many subtypes of AML, all are typically managed using a standard chemotherapy regimen of an anthracycline plus cytarabine arabinoside (CA). Despite high rates of complete remission following standard chemotherapy, most patients relapse and long-term disease-free survival is only 30-40%. The introduction of drugs such as all-trans retinoic acid (ATRA) that promote progenitor differentiation by directly inhibiting the PML-RARα fusion protein has changed the treatment paradigm for APL and markedly improved patient survival. The purposes of the present review are to provide the latest results and future directions of clinical research into APL and to illustrate how new therapies, such as ATRA plus anthracycline-based induction and consolidation therapy, risk-adapted therapy, salvage therapy containing arsenic trioxide-based regimens, and hematopoietic stem cell transplantation, have improved the treatment outcomes for APL patients.     

Relapsed acute lymphoblastic leukemia: Current status and future opportunities

Significant improvements in primary therapy for childhood acute lymphoblastic leukemia (ALL) have led to dramatic increases in cure rates over the past few decades. Relapsed ALL, however, remains more common than new diagnoses of many common pediatric malignancies. Outcomes for patients with relapsed ALL remain poor, especially for patients with early bone marrow relapse. However, most relapse patients do achieve a second complete remission, followed by therapeutic options including further chemotherapy and hematopoietic stem cell transplant. The level of minimal residual disease after achieving second remission or before transplant may predict outcomes. The substantial likelihood of achieving second remission with familiar drug combinations may discourage participation in formal relapse studies. The high likelihood of achieving a third remission may discourage participation in single-gent trials of new drugs, despite the critical need for novel agents with activity against resistant disease that may improve outcomes for recurrent ALL.     

Outcome of treatment after first relapse in younger adults with acute myeloid leukemia initially treated by the ALFA-9802 trial

Forty-seven percent of adults with acute myeloid leukemia (AML) who entered the ALFA-9802 trial and achieved a first complete remission (CR) experienced a first relapse. We examined the outcome of these 190 adult patients. Eighty-four patients (44%) achieved a second CR. The median overall survival (OS) after relapse was 8.9 months with a 2-year OS at 25%. Factors predicting a better outcome after relapse were stem cell transplant (SCT) performed in second CR and a first CR duration >1 year. Risk groups defined at the time of diagnosis and treatment received in first CR also influenced the outcome after relapse. The best results were obtained in patients with core binding factor (CBF)-AML, while patients initially defined as favorable intermediate risk showed a similar outcome after relapse than those initially entering the poor risk group. We conclude that most adult patients with recurring AML could not be rescued using current available therapies, although allogeneic SCT remains the best therapeutic option at this stage of the disease.     

Extramedullary relapse in a patient with acute promyelocytic leukemia: successful treatment with arsenic trioxide, all-trans retinoic acid and gemtuzumab ozogamicin therapies

Acute promyelocytic leukemia (APL) is characterized by the presence of the t(15;17) translocation, resulting in the PML-RAR fusion protein. Standard treatment consists of the combination of all-trans retinoic acid (ATRA) with an anthracycline that results in complete remission (CR) rates in excess of 90%. Recently, several new agents have been shown to have clinical activity in APL. These include a liposomal formulation of ATRA (lipo-ATRA), and gemtuzumab ozogamicin (GO). Herein, we report a patient with APL who relapsed with extramedullary disease 2.5 years after lipo-ATRA therapy and was successfully treated with the sequence of A2O3, ATRA, and GO and we summarize our experience with patients with isolated extramedullary relapse in APL.     

Treatment of relapsed acute myeloid leukemia after allogeneic bone marrow transplantation with chemotherapy followed by G-CSF-primed donor leukocyte infusion: a high incidence of isolated extramedullary relapse.

For patients with acute myeloid leukemia (AML) relapsed after allogeneic bone marrow transplantation (BMT), donor leukocyte infusion (DLI) as sole therapy has very limited efficacy. We tested the effects of cytoreductive chemotherapy, followed immediately by G-CSF-primed DLI (chemotherapy followed by DLI, Chemo-DLI), in 16 AML patients who relapsed after allogeneic BMT. In all, 10 of these patients achieved complete remission (CR), four of whom remain alive in CR at a median follow-up of 1488 days after DLI. The 2-year overall survival (OS) for the entire cohort was 31%. The 1-year OS for patients with post-BMT remission of 6 months or longer was 55%, compared with 0% for patients with post-BMT remission of less than 6 months, making post-BMT remission duration the only significant prognostic factor for OS (P=0.015). These findings suggest that Chemo-DLI could induce durable remissions in a proportion of relapsed AML patients with relatively long post-BMT remission duration. All five patients who relapsed after achieving CR with Chemo-DLI relapsed at extramedullary sites in the presence of continuous bone marrow remission, suggesting uneven graft-versus-leukemia effects in different parts of the body. Although our data should be interpreted cautiously considering the limited number of patients, isolated extramedullary relapse seems to be common after Chemo-DLI.     

SOHO State of the Art Updates and Next Questions |The Role of Maintenance Therapy in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive disease predominantly affecting the elderly population. Although, up to 65% of patients with AML achieve a complete remission with standard induction chemotherapy, the majority of patients will relapse and succumb to the disease. Although maintenance therapy is a component of standard management for various hematological malignancies, such as acute lymphoblastic leukemia (ALL), acute promyelocytic leukemia (APL) or multiple myeloma, past studies investigating the role of maintenance therapy in AML were unable to demonstrate an advantage in overall survival, and therefore, it has not been an established practice in the treatment of AML. For patients, who are not candidates for stem cell transplant, effective AML maintenance therapies are needed in order to reduce the risk of relapse. Over the past decades, many investigators have examined the role of various maintenance strategies in AML; with the intention to prolong remission and overall survival. This review will provide an overview of prior and ongoing approaches and strategies to maintenance therapy for AML.     

Mitoxantrone and ara-C in previously treated patients with acute myelogenous leukemia

Mitoxantrone is a synthetic aminoanthraquinone we have previously reported to be effective for patients with acute leukemia in relapse. We presently report the results of a trial of mitoxantrone in combination with cytosine arabinoside (ara-C) in patients with refractory or relapsed acute myelocytic leukemia (AML). Forty-nine patients, 24 males and 25 females, with a median age of 56, of whom 32 were in first relapse, four were in second relapse, and 13 had primarily refractory AML, were treated with mitoxantrone 10 mg/m2 daily for 3 days and ara-C 100 mg/m2 daily by continuous infusion for 7 days. Twenty patients (62.5%) with first relapse AML achieved M1 marrow, whereas only two of 13 patients with refractory AML did; none of four patients with more than one prior remission responded. Marrow recovery was observed in a median of 32 days. Remissions were maintained with monthly ara-C plus mitoxantrone alternating with ara-C plus 6-TG; median duration of remission was 8 months and two patients are in continuing remission at 8 and 16 months. Treatment was well tolerated, with minimal nausea and vomiting, diarrhea, drug-induced mucositis. Treatment-related cardiac toxicity was not observed. Transient hepatic dysfunction was observed in greater than 50% of courses. Mitoxantrone plus ara-C is an active combination with great promise for the therapy of previously untreated patients with AML.     

Characteristics and outcomes of acute myelogenous leukemia patients with very late relapse (>5 years)

The clinical characteristics and outcome of 15 patients with acute myelogenous leukemia (AML) who experienced relapse at least 5 years after induction of complete remission (very late-relapse AML) are described. This subgroup represented 3% of all relapsed patients seen at this institution over the same time period. There were eight males in this cohort and the median age at diagnosis was 48 years (range 13 - 77 years). Nine patients had M4/M5 French - American - British (FAB) classification subtype and most had intermediate risk cytogenetics. The median duration of first complete remission (CR-1) was 9 years (range 5.2 - 11.5 years). Thirteen patients (86%) achieved CR-2 with reinduction therapy. The 5-year relapse-free survival and overall survival rates of this cohort were 59% and 51%, respectively. We conclude that very late-relapse AML is a rare event, and that reinduction in these patients is associated with very high CR rates and a potential cure fraction.