Therapy for elderly patients with acute myeloid leukemia: a problem in search of solutions

Harnessing the Immune System Against Leukemia: Monoclonal Antibodies and Checkpoint Strategies for AML

Acute myeloid leukemia (AML) is the most common leukemia among adults and is associated with a poor prognosis, especially in patients with adverse prognostic factors, older age, or relapsed disease. The last decade has seen a surge in successful immune-based therapies in various solid tumors; however, the role of immune therapies in AML remains poorly defined. This chapter describes the rationale, clinical data, and toxicity profiles of immune-based therapeutic modalities in AML including naked and conjugated monoclonal antibodies, bispecific T-cell engager antibodies, chimeric antigen receptor (CAR)-T cells, and checkpoint blockade via blockade of PD1/PDL1 or CTLA4. Monoclonal antibodies commonly used in AML therapy target highly expressed "leukemia" surface antigens and include (1) naked antibodies against common myeloid markers such as anti-CD33 (e.g., lintuzumab), (2) antibody-drug conjugates linked to either, (a) a highly potent toxin such as calicheamicin, pyrrolobenzodiazepine, maytansine, or others in various anti-CD33 (gemtuzumab ozogamicin, SGN 33A), anti-123 (SL-401), and anti-CD56 (lorvotuzumab mertansine) formulations, or (b) radioactive particles, such as 131I, 213Bi, or 225Ac-labeled anti-CD33 or CD45 antibodies. Novel monoclonal antibodies that recruit and promote proximity-induced cytotoxicity of tumor cells by T cells (bispecific T-cell engager [BiTE] such as anti CD33/CD3, e.g., AMG 330) or block immune checkpoint pathways such as CTLA4 (e.g., ipilimumab) or PD1/PD-L1 (e.g., nivolumab) unleashing the patients T cells to fight leukemic cells are being evaluated in clinical trials in patients with AML. The numerous ongoing clinical trials with immunotherapies in AML will improve our understanding of the biology of AML and allow us to determine the best approaches to immunotherapy in AML.

Acute myeloid leukemia: advancing clinical trials and promising therapeutics

Recent progress in understanding the biology of acute myeloid leukemia (AML) and the identification of targetable driver mutations, leukemia specific antigens and signal transduction pathways has ushered in a new era of therapy. In many circumstances the response rates with such targeted or antibody-based therapies are superior to those achieved with standard therapy and with decreased toxicity. In this review we discuss novel therapies in AML with a focus on two major areas of unmet need: (1) single agent and combination strategies to improve frontline therapy in elderly patients with AML and (2) molecularly targeted therapies in the frontline and salvage setting in all patients with AML.

A phase II study of decitabine and gemtuzumab ozogamicin in newly diagnosed and relapsed acute myeloid leukemia and high-risk myelodysplastic syndrome

Decitabine may open the chromatin structure of leukemia cells making them accessible to the calicheamicin epitope of gemtuzumab ozogamicin (GO). A total of 110 patients (median age 70 years; range 27-89 years) were treated with decitabine and GO in a trial designed on model-based futility to accommodate subject heterogeneity: group 1: relapsed/refractory acute myeloid leukemia (AML) with complete remission duration (CRD) <1 year (N=28, 25%); group 2: relapsed/refractory AML with CRD ⩾1 year (N=5, 5%); group 3: untreated AML unfit for intensive chemotherapy or untreated myelodysplastic syndrome (MDS) or untreated myelofibrosis (MF; N=57, 52%); and group 4: AML evolving from MDS or relapsed/refractory MDS or MF (N=20, 18%). Treatment consisted of decitabine 20 mg/m(2) daily for 5 days and GO 3 mg/m(2) on day 5. Post-induction therapy included five cycles of decitabine+GO followed by decitabine alone. Complete remission (CR)/CR with incomplete count recovery was achieved in 39 (35%) patients; group 1= 5/28 (17%), group 2=3/5 (60%), group 3=24/57 (42%) and group 4=7/20 (35%). The 8-week mortality in groups 3 and 4 was 16% and 10%, respectively. Common drug-related adverse events included nausea, mucositis and hemorrhage. Decitabine and GO improved the response rate but not overall survival compared with historical outcomes in untreated AML ⩾60 years.

Acute myeloid leukemia after myelodysplastic syndrome and failure of therapy with hypomethylating agents: an emerging entity with a poor prognosis

We assessed the outcomes of 63 patients with acute myeloid leukemia (AML) arising from myelodysplastic syndrome (MDS) after hypomethylating agent failure. Their median age was 63 years. All 63 patients had received ≥ 1 salvage regimens for AML, and 35 patients (55%) had received ≥ 2. Of the 31 patients (49%) who had received high-dose cytarabine (HDAC) at first relapse, 2 (6%) achieved complete remission (CR) and 4 (13%) CR with incomplete platelet recovery (overall response rate, 19%). Of the 32 patients (51%) who had received other treatments, including investigational agents, 4 (12%) achieved CR and 4 (12%) CR with incomplete platelet recovery (overall response rate, 24%). The median response duration was 20 weeks. With a median follow-up of 42 months from the AML diagnosis, the median survival (21 weeks) was similar between the 2 groups. The 1- and 2-year survival rate was 19% and 8%, respectively. Multivariate analysis identified low albumin, HDAC treatment, and platelet count < 50 × 10(9)/L as independent adverse factors for CR and a platelet count < 50 × 10(9)/L and age > 65 years as independent adverse factors for survival. Thus, the outcome of AML evolving from MDS after hypomethylating agent failure is poor and not improved with HDAC. Novel therapies directed toward this emerging entity are urgently needed.

Oral sapacitabine for the treatment of acute myeloid leukaemia in elderly patients: a randomised phase 2 study

BACKGROUND

Available treatments for acute myeloid leukaemia (AML) have limited durable activity and unsatisfactory safety profiles in most elderly patients. We assessed the efficacy and toxicity of sapacitabine, a novel oral cytosine nucleoside analogue, in elderly patients with AML.

METHODS

In this randomised, phase 2 study, we recruited patients with AML who were either treatment naive or at first relapse and who were aged 70 years or older from 12 centres in the USA. We used a computer-generated randomisation sequence to randomly allocate eligible patients to receive one of three schedules of oral sapacitabine (1:1:1; stratified by a history of AML treatment): 200 mg twice a day for 7 days (group A); 300 mg twice a day for 7 days (group B); and 400 mg twice a day for 3 days each week for 2 weeks (group C). All schedules were given in 28 day cycles. To confirm the safety and tolerability of dosing schedules, after 20 patients had been treated in a group we enrolled an expanded cohort of 20-25 patients to that group if at least four patients had achieved complete remission or complete remission with incomplete blood count recovery, and if the 30 day death rate was 20% or less. Our primary endpoint was 1-year overall survival, analysed by intention-to-treat (ie, patients who have received at least one dose of sapacitabine) in those patients who had been randomly allocated to treatment. This trial is registered with ClinicalTrials.gov, number NCT00590187.

RESULTS

Between Dec 27, 2007, and April 21, 2009, we enrolled 105 patients: 86 patients were previously untreated and 19 were at first relapse. Of the 60 patients randomly allocated to treatment, 1-year overall survival was 35% (95% CI 16-59) in group A, 10% (2-33) in group B, and 30% (13-54) in group C. 14 (13%) of 105 patients died within 30 days and 27 (26%) died within 60 days. The most common grade 3-4 adverse events were anaemia (eight of 40 patients in group A, 12 of 20 patients in group B, and 15 of 45 patients in group C), neutropenia (14 in group A, 10 in group B, 11 in group C), thrombocytopenia (24 in group A, 12 in group B, and 22 in group C), febrile neutropenia (16 in group A, nine in group B, and 22 in group C), and pneumonia (seven in group A, five in group B, and 10 in group C). The most common grade 5 events were pneumonia (two in group A, one in group B, and three in group C) and sepsis (six in group A, three in group B, and one in group C). Seven deaths were thought to be probably or possibly related to sapacitabine treatment.

INTERPRETATION

Sapacitabine seems active and tolerable in elderly patients with AML. The 400 mg dose schedule had the best efficacy profile. Future investigations should aim to combine sapacitabine with other low-intensity therapies in elderly patients with AML.

FUNDING

Cyclacel Limited.

A retrospective study of leukemia epidemiology in Northern Tunisia

A hospital-based epidemiological study of leukemia was carried out in the northern part of Tunisia during a 5-year period, from 1999 to 2003. Of 402 Tunisians diagnosed with leukemia, 344 (85.6%) had acute leukemia and 58 (14.4%) had chronic leukemia. Age-specific incidence rates for acute lymphoid leukemia (ALL), acute myeloid leukemia (AML), chronic lymphoid leukemia (CLL) and chronic myeloid leukemia (CML) are described. The distribution of leukemia in the governorate of Nabeul was established. These results are useful for the organization and follow-up of medical care.

A phase I study of pemetrexed in patients with relapsed or refractory acute leukemia

PURPOSE

To investigate the toxicity profile, activity, pharmacokinetics, and pharmacodynamics of pemetrexed in leukemia.

PATIENTS AND METHODS

Patients with refractory or relapsed acute leukemia were eligible. A phase I 3+3 design was implemented. Pemetrexed was infused intravenously (IV) over 25 min with vitamin supplementation. Courses were repeated every 3 to 4 weeks according to toxicity and efficacy. The starting dose of 900 mg/m² was escalated by approximately 33% until the dose-limiting toxicity (DLT) was determined.

RESULTS

Twenty patients with acute myeloid (AML) or lymphocytic (ALL) leukemia received therapy. The main non-hematologic adverse event was liver dysfunction at several dose levels, including 2 DLTs at 3,600 mg/m². One patient with ALL (3,600 mg/m² dose level) achieved a partial response. Pemetrexed pharmacokinetics were linear with escalated dosing. Elevated plasma deoxyuridine was observed in a subset of patients following pemetrexed infusion, but was not correlated with dose levels. Changes in the nucleotide pools of circulating mononuclear cells were observed, but were variable.

CONCLUSIONS

The recommended phase II dose of pemetrexed for future leukemia studies is 2,700 mg/m(2) IV over 25 min every 3 to 4 weeks with vitamin supplementation. Deoxyuridine levels did not increase with increasing pemetrexed dose, suggesting pemetrexed inhibition of thymidylate synthase (TS) may be saturated by the 900 mg/m² dose level. However, no firm conclusion can be made regarding TS saturation in tumor cells. While tolerable, pemetrexed monotherapy had limited activity in this highly refractory population. Exploration of pemetrexed in combination with other active agents in leukemia is a reasonable future endeavor.

Intensive chemotherapy does not benefit most older patients (age 70 years or older) with acute myeloid leukemia

Patients ≥ 70 years of age with acute myeloid leukemia (AML) have a poor prognosis. Recent studies suggested that intensive AML-type therapy is tolerated and may benefit most. We analyzed 446 patients ≥ 70 years of age with AML (≥ 20% blasts) treated with cytarabine-based intensive chemotherapy between 1990 and 2008 to identify risk groups for high induction (8-week) mortality. Excluding patients with favorable karyotypes, the overall complete response rate was 45%, 4-week mortality was 26%, and 8-week mortality was 36%. The median survival was 4.6 months, and the 1-year survival rate was 28%. Survival was similar among patients treated before 2000 and since 2000. A multivariate analysis of prognostic factors for 8-week mortality identified the following to be independently adverse: age ≥ 80 years, complex karyotypes, (≥ 3 abnormalities), poor performance (2-4 Eastern Cooperative Oncology Group), and elevated creatinine > 1.3 mg/dL. Patients with none (28%), 1 (40%), 2 (23%), or ≥ 3 factors (9%) had estimated 8-week mortality rates of 16%, 31%, 55%, and 71% respectively. The 8-week mortality model also predicted for differences in complete response and survival rates. In summary, the prognosis of most patients (72%) ≥ 70 years of age with AML is poor with intensive chemotherapy (8-week mortality ≥ 30%; median survival < 6 months).

Acute pulmonary failure during remission induction chemotherapy in adults with acute myeloid leukemia or high-risk myelodysplastic syndrome

BACKGROUND

Acute pulmonary failure during remission induction therapy is a serious complication in patients with acute myeloid leukemia (AML). To the authors' knowledge, the course and prognosis of such patients is not well known.

METHODS

A total of 1541 patients referred for remission induction chemotherapy of AML or high-risk myelodysplastic syndrome were retrospectively reviewed.

RESULTS

A total of 120 (8%) patients developed acute pulmonary failure within 2 weeks of the initiation of chemotherapy; 87 of these patients (73%) died during remission induction, whereas 17 (14%) achieved a complete response. The median survival among the 120 patients with early acute pulmonary failure was 3 weeks. Predictive factors for the development of early acute pulmonary failure by multivariate analysis were: male sex (P = .00038), acute promyelocytic leukemia (P = .00003), poor performance status (P = .001), lung infiltrates at diagnosis (P = .000001), and increased creatinine (P = .000005). Patients who had 0 to 1, 2, 3, or 4 to 5 adverse factors were found to have estimated predictive incidences of acute pulmonary failure of 3%, 13%, 23%, and 34%, respectively.

CONCLUSIONS

Preventive approaches at the start of induction therapy in patients at high risk of pulmonary failure may improve the outcome of these patients.

Therapeutic advances in leukemia and myelodysplastic syndrome over the past 40 years

Major therapeutic progress has been accomplished in leukemia and myelodysplastic syndrome (MDS) over the past 40 years, which may not be fully appreciated by the larger medical community. The objective of this review was to briefly highlight the treatment breakthroughs in leukemia and MDS. Therapeutic progress happened through better understanding of disease pathophysiologies and rational development of targeted agents, like imatinib mesylate in chronic myeloid leukemia (CML), and through astute, empirical discoveries in the clinic, like all-trans retinoic acid and arsenic trioxide in acute promyelocytic leukemia (APL) and chlorodeoxyadenosine in hairy cell leukemia (HCL). Today, the 5- to 10-year survival rates in patients with APL and HCL exceed 80%. In patients with CML, imatinib therapy has been associated with estimated 5- to 7-year survival rates from 85% to 90%. In patients with adult acute lymphocytic leukemia, modern intensive regimens have improved the 5-year survival rates from 20% up to 40%. In patients with chronic lymphocytic leukemia, chemoimmunotherapy recently produced high rates of quality responses and improved long-term outcome. In younger patients with acute myeloid leukemia (AML), the 5-year survival rates range from 40% to 50%, although elderly AML remains a therapeutic challenge. In patients with MDS, it was recently demonstrated that epigenetic therapy with hypomethylating agents improved survival. Much therapeutic progress has been witnessed in leukemia and MDS, and much more is expected to occur soon.