10-day decitabine versus 3 + 7 chemotherapy followed by allografting in older patients with acute myeloid leukaemia: an open-label, randomised, controlled, phase 3 trial

BACKGROUND

Many older patients with acute myeloid leukaemia die or cannot undergo allogeneic haematopoietic stem-cell transplantation (HSCT) due to toxicity caused by intensive chemotherapy. We hypothesised that replacing intensive chemotherapy with decitabine monotherapy could improve outcomes.

METHODS

This open-label, randomised, controlled, phase 3 trial was conducted at 54 hospitals in nine European countries. Patients aged 60 years and older who were newly diagnosed with acute myeloid leukaemia and had not yet been treated were enrolled if they had an Eastern Cooperative Oncology Group performance status of 2 or less and were eligible for intensive chemotherapy. Patients were randomly assigned (1:1) to receive decitabine or standard chemotherapy (known as 3 + 7). For the decitabine group, decitabine (20 mg/m2) was administered for the first 10 days in the first 28-day cycle, followed by 28-day cycles consisting of 5 days or 10 days of decitabine. For the 3 + 7 group, daunorubicin (60 mg/m2) was administered over the first 3 days and cytarabine (200 mg/m2) over the first 7 days, followed by 1-3 additional chemotherapy cycles. Allogeneic HSCT was strongly encouraged. Overall survival in the intention-to-treat population was the primary endpoint. Safety was assessed in all patients who received the allocated treatment. This trial is registered at ClinicalTrials.gov, NCT02172872, and is closed to new participants.

FINDINGS

Between Dec 1, 2014, and Aug 20, 2019, 606 patients were randomly assigned to the decitabine (n=303) or 3 + 7 (n=303) group. Following an interim analysis which showed futility, the IDMC recommended on May 22, 2019, that the study continued as planned considering the risks and benefits for the patients participating in the study. The cutoff date for the final analysis presented here was June 30, 2021. At a median follow-up of 4·0 years (IQR 2·9-4·8), 4-year overall survival was 26% (95% CI 21-32) in the decitabine group versus 30% (24-35) in the 3 + 7 group (hazard ratio for death 1·04 [95% CI 0·86-1·26]; p=0·68). Rates of on-protocol allogeneic HSCT were similar between groups (122 [40%] of 303 patients for decitabine and 118 [39%] of 303 patients for 3+7). Rates of grade 3-5 adverse events were 254 (84%) of 302 patients in the decitabine group and 279 (94%) of 298 patients in the 3 + 7 group. The rates of grade 3-5 infections (41% [125 of 302] vs 53% [158 of 298]), oral mucositis (2% [seven of 302] vs 10% [31 of 298]) and diarrhoea (1% [three of 302] vs 8% [24 of 298]) were lower in the decitabine group than in the 3 + 7 group. Treatment-related deaths were reported for 12% (35 of 302) of patients in the decitabine group and 14% (41 of 298) in the 3 + 7 group.

INTERPRETATION

10-day decitabine did not improve overall survival but showed a better safety profile compared with 3 + 7 chemotherapy in older patients with acute myeloid leukaemia eligible for intensive chemotherapy. Decitabine could be considered a better-tolerated and sufficiently efficacious alternative to 3 + 7 induction in fit older patients with acute myeloid leukaemia without favourable genetics.

FUNDING

Janssen Pharmaceuticals.

Dose intensity for induction in acute myeloid leukemia: what, when, and for whom?

Intensive chemotherapy has been the backbone of the treatment of acute myeloid leukemia (AML) for decades. However, an increase in novel targeted agents, which has been brought about in part by a deeper understanding of the genetic makeup of AML, has led to remission-inducing regimens that do not require traditional cytotoxic agents. Combinations of a hypomethylating agent (HMA) and venetoclax have doubled the chance of remission for patients considered unfit for induction chemotherapy who would have traditionally been offered singleagent HMA. In fact, this regimen may rival the complete remission rate achieved with induction chemotherapy for certain populations such as the very elderly and those with secondary AML, but equivalency has yet to be established. Further advances include the addition of gemtuzumab ozogamicin and FLT3 inhibitors to induction chemotherapy, which improves survival for patients with core-binding factor and FLT3-mutated AML, respectively. Still, much work is needed to improve the outcomes of the highest-risk subgroups: frail patients and those with high-risk cytogenetics and/or TP53 mutations. Promisingly, the landscape of AML therapy is shifting dramatically and no longer is intensity, when feasible, always the best answer for AML.

DNA-hypomethylating agents as epigenetic therapy before and after allogeneic hematopoietic stem cell transplantation in myelodysplastic syndromes and juvenile myelomonocytic leukemia

Myelodysplastic syndrome (MDS) is a clonal bone marrow disorder, typically of older adults, which is characterized by ineffective hematopoiesis, peripheral blood cytopenias and risk of progression to acute myeloid leukemia. Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative neoplasm occurring in young children. The common denominator of these malignant myeloid disorders is the limited benefit of conventional chemotherapy and a particular responsiveness to epigenetic therapy with the DNA-hypomethylating agents 5-azacytidine (azacitidine) or decitabine. However, hypomethylating therapy does not eradicate the malignant clone in MDS or JMML and allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative treatment option. An emerging concept with intriguing potential is the combination of hypomethylating therapy and HSCT. Possible advantages include disease control with good tolerability during donor search and HSCT preparation, improved antitumoral alloimmunity, and reduced risk of relapse even with non-myeloablative regimens. Herein we review the current role of pre- and post-transplant therapy with hypomethylating agents in MDS and JMML.

Addition of 10-Day Decitabine to Fludarabine/Total Body Irradiation Conditioning is Feasible and Induces Tumor-Associated Antigen-Specific T Cell Responses

Allogeneic hematopoietic cell transplantation (HCT) offers the possibility of curative therapy for patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myelogenous leukemia (AML). However, post-HCT relapse remains a major problem, particularly in patients with high-risk cytogenetics and in patients who cannot tolerate consolidation chemotherapy (eg, due to previous toxicity). We assessed the toxicity and efficacy of 10-day decitabine (Dec), fludarabine (Flu), and 2 Gy total body irradiation (TBI) as a new conditioning regimen for allogeneic HCT in patients with MDS, CMML, or AML. Thirty patients were enrolled, including 11 with MDS, 2 with CMML, and 17 with AML. Patients received 20 mg/m(2)/day Dec on days -11 to -2, 30 mg/m(2)/day Flu on days -4 to -2, and 2 Gy TBI on day -1, followed by infusion of a donor stem cell graft on day 0. Postgrafting immunosuppression consisted of cyclosporin A and mycophenolate mofetil. At a median follow-up of 443 days, the overall survival was 53%, relapse incidence was 27%, and nonrelapse mortality was 27%. The incidence of severe acute (grade III/IV) graft-versus-host disease (GVHD) was 27%, and that of (predominantly mild) chronic GVHD was 60%. Immunomonitoring studies revealed that specific CD8(+) T cell responses against epigenetically silenced tumor-associated antigens (TAAs), including cancer-testis antigens (MAGE-A1/A2/A3 and PRAME) and RHAMM, occurred more frequently in patients who had received Dec/Flu/TBI conditioning (8 of 11 patients) compared with a control group of patients who had received only Flu/TBI conditioning (2 of 9 patients). In summary, Dec/Flu/TBI conditioning proved feasible and effective and enhanced the induction of TAA-reactive CD8(+) T cell responses in vivo, which may contribute to disease control post-transplantation.

Long-term follow-up of therapy-related myelodysplasia and AML patients treated with allogeneic hematopoietic cell transplantation

The outcome of patients with therapy-related myelodysplasia (t-MDS) or t-AML is very poor. The only curative treatment option implements allogeneic hematopoietic cell transplantation (aHCT); however, long-term follow-up data beyond 5 years are scarce. Here we report on a cohort of 79 consecutive patients with a median age of 58 years (range (r): 20-76) at transplantation and a median follow-up of 7.5 years (r: 0.07-19.0). Only 19 (24.1%) patients were in CR before aHCT. Non-relapse mortality and relapse rates were 23% (95% confidence interval, 15-35%) and 42% (32-55%) at 5 years, and 32% (22-46%) and 44% (34-57%) at 10 years, respectively. Disease-free survival (DFS) and overall survival (OS) rates were 35% (24-46%) and 38% (27-49%) at 5 years, and 24% (14-36%) and 24% (13-36%) at 10 years, respectively. Although cytogenetic aberrations were associated with shorter DFS and higher relapse risk, persistent disease at the time of transplantation, an unrelated donor and patient age were not associated with shorter OS. In conclusion, long-term survival beyond 10 years of t-MDS/t-AML patients after aHCT is possible, even for refractory patients. Therefore, early donor search and rapid transplantation are warranted, also to decrease the risk of disease-related deterioration of patients' performance status.

Clinical Results of Hypomethylating Agents in AML Treatment

Epigenetic changes play an important role in the development of acute myeloid leukemia (AML). Unlike gene mutations, epigenetic changes are potentially reversible, which makes them attractive for therapeutic intervention. Agents that affect epigenetics are the DNA methyltransferase inhibitors, azacitidine and decitabine. Because of their relatively mild side effects, azacitidine and decitabine are particularly feasible for the treatment of older patients and patients with co-morbidities. Both drugs have remarkable activity against AML blasts with unfavorable cytogenetic characteristics. Recent phase 3 trials have shown the superiority of azacitidine and decitabine compared with conventional care for older AML patients (not eligible for intensive treatment). Results of treatment with modifications of the standard azacitidine (seven days 75 mg/m(2) SC; every four weeks) and decitabine (five days 20 mg/m(2) IV; every four weeks) schedules have been reported. Particularly, the results of the 10-day decitabine schedule are promising, revealing complete remission (CR) rates around 45% (CR + CRi (i.e., CR with incomplete blood count recovery) around 64%) almost comparable with intensive chemotherapy. Application of hypomethylating agents to control AML at the cost of minimal toxicity is a very promising strategy to "bridge" older patients with co-morbidities to the potential curative treatment of allogeneic hematopoietic cell transplantation. In this article, we discuss the role of DNA methyltransferase inhibitors in AML.

Pretransplantation 5-azacitidine in high-risk myelodysplastic syndrome

We prospectively evaluated the allogeneic hematopoietic cell transplantation (HCT) outcomes in high-risk myelodysplastic syndrome (MDS) patients who received pretransplantation 5-azacitidine. Twenty-five patients evaluated for allogeneic HCT consult and considered medically eligible for a donor search were enrolled. Azacitidine was administered at 75 mg/m(2) for 5 to 7 days every 4 weeks until a suitable donor was found. A median of 3 (range, 0 to 6) cycles of 5-azacitidine were administered. Preallogeneic HCT responses to 5-azacitidine, based on the International Working Group criteria, were 48% partial response, 33% stable disease, and 19% progressive disease. Four patients did not proceed to allogeneic HCT. Twenty-one patients, a median age of 55 (range, 25 to 67) years, received allogeneic HCT after myeloablative pharmacokinetically targeted i.v. busulfan and fludarabine conditioning regimen. Donors were either HLA-matched related or unrelated, except for 1 mismatch unrelated donor. With a median follow-up of 30 months, 1-year relapse-free and overall survivals were 52% (95% confidence interval [CI], 30% to 71%) and 62% (95% CI, 38% to 79%), respectively. Preallogeneic HCT 5-azacitidine administration was well tolerated and provided reasonable disease control before allogeneic HCT. (Registered at ClinicalTrials.gov as NCT00660400).

Decitabine in the treatment of acute myeloid leukemia in elderly patients

The majority of patients with acute myeloid leukemia (AML) are elderly and have a poor prognosis despite induction therapy. Decitabine, a DNA-hypomethylating agent that induces differentiation and apoptosis of leukemic cells, is a well-tolerated alternative to aggressive chemotherapy. It is currently FDA-approved for myelodysplastic syndrome, including patients with 20%–30% bone marrow blasts. Recent clinical attention has focused on evaluating decitabine as frontline therapy for untreated high-risk elderly AML patients. A large randomized international phase III study comparing decitabine to supportive care and cytarabine in elderly AML patients demonstrated significantly improved complete remission rates, but the survival difference did not reach significance. Due to this, decitabine did not achieve FDA approval for AML, but continues to be used off-label. Current research is focused on further defining subgroups of elderly AML patients who may derive greater benefit from decitabine therapy and combining it with other low-intensity active agents for AML.

Decitabine

Besides 5-azacytidine (azacitidine, Vidaza®), 5-aza-2'-deoxycytidine (decitabine, Dacogen®) is the most widely used inhibitor of DNA methylation, which triggers demethylation leading to consecutive reactivation of epigenetically silenced tumor suppressor genes in vitro and in vivo. Although antileukemic activity of decitabine is known for almost 40 years, its therapeutic potential in hematologic malignancies has only recently led to its approval in higher-risk MDS patients and as first-line treatment in AML patients>65 years who are not candidates for intensive chemotherapy. Several clinical trials showed promising activity of low-dose decitabine also in CML and hemoglobinopathies, whereas its efficacy in solid tumors is very limited. Clinical responses appear to be exerted both by epigenetic alterations and by induction of cell-cycle arrest and/or apoptosis. Recent and ongoing clinical trials investigate new dosing schedules, routes of administration, and combination of decitabine with other agents, including histone deacetylase inhibitors.