A phase 2 study of lenalidomide monotherapy in patients with deletion 5q acute myeloid leukemia: Southwest Oncology Group Study S0605

Lenalidomide as a novel treatment of acute myeloid leukemia

INTRODUCTION

Lenalidomide is an oral immunomodulatory drug derived from thalidomide. This drug has been approved by the Food and Drug Administration for transfusion-dependent anemia due to low-risk myelodysplastic syndromes (MDS) associated with deletion 5q abnormality with or without additional cytogenetic abnormalities and multiple myeloma in combination with dexamethasone. Trials have been conducted for its use in higher-risk MDS and acute myeloid leukemia (AML).

AREAS COVERED

The pharmacokinetic and mechanism of action are discussed and clinical studies of lenalidomide in AML are reported herein in detail. An overview of safety and tolerability is also presented.

EXPERT OPINION

Lenalidomide has clinical activity in AML with manageable toxicity. The population that would benefit from lenalidomide and optimal dose needs to be better defined. Recent trials have focused on combining lenalidomide with other agents active in MDS and AML and promising data are emerging.

Sequential azacitidine plus lenalidomide combination for elderly patients with untreated acute myeloid leukemia

There are limited treatment options for older patients with acute myeloid leukemia and prognosis of these patients remains poor, thereby warranting development of novel therapies. We evaluated the efficacy and safety of azacitidine in combination with lenalidomide as front-line therapy for older patients with acute myeloid leukemia. Patients ≥ 60 years of age with untreated acute myeloid leukemia received azacitidine 75 mg/m2 for 7 days followed by escalating doses of lenalidomide daily for 21 days starting on day 8 of each cycle every 6 weeks. Patients received continued therapy until disease progression, unacceptable toxicity, or completion of 12 cycles. Forty-two patients (median age, 74 years) were enrolled with equal distribution according to European LeukemiaNet risk. The overall response rate was 40% (rate of complete remission with or without complete recovery of blood counts = 28%). The median time to complete remission with or without complete recovery of blood counts was 12 weeks, and duration of this status was 28 weeks (range, 4 - >104 weeks). Therapy-related acute myeloid leukemia and a high score on the Hematopoietic Cell Transplantation Comorbidity Index were negative predictors of response. Early death was noted in 17% of patients. Grades ≥ 3 toxicities were uncommon and most adverse events were gastrointestinal, fatigue and myelosuppression. In conclusion, a sequential combination of azacitidine plus lenalidomide has clinical activity in older patients with acute myeloid leukemia, and further studies of this combination are underway.

Novel and emerging drugs for acute myeloid leukemia

Acute myeloid leukemia (AML) is a challenging disease to treat with the majority of patients dying from their illness. While overall survival has been markedly prolonged in acute promyelocytic leukemia (APL), survival in younger adults with other subtypes of AML has only modestly improved over the last twenty years. Physicians who treat AML eagerly await drugs like Imatinib for chronic myeloid leukemia, Cladribine for hairy cell leukemia, and Rituximab for non-Hodgkin Lymphoma which have had an important impact on improving outcome. Recent research efforts have focused on refining traditional chemotherapeutic agents to make them more active in AML, targeting specific genetic mutations in myeloid leukemia cells, and utilizing novel agents such as Lenalidomide that have shown activity in other hematologic malignancies. Here, we focus on reviewing the recent literature on agents that may assume a role in clinical practice for patients with AML over the next five years.

Acute myeloid leukemia in the elderly

SUMMARY Acute myeloid leukemia in older patients is of poor outcome, characterized by a specific biology of acute myeloid leukemia and factors related to the patient’s physical condition. Aggressive therapy results in improved survival and quality of life when compared with palliative care. However, not all patients are candidates for such therapy. Disease often demonstrates resistance related to poor-risk cytogenetics, and patients are often unable to tolerate intensive chemotherapy. For those patients, novel agents are being investigated. Understanding of the disease biology, as well as the prognostic factors associated with the host, allows the better estimation of which patients are likely to benefit from standard therapy and which require alternative approaches.

Phase 2 study of the lenalidomide and azacitidine combination in patients with higher-risk myelodysplastic syndromes

Lenalidomide and azacitidine each have activity in myelodysplastic syndromes (MDS) patients, where both microenvironment and cell-regulatory mechanisms contribute to disease pathogenesis. The objective of this multicenter, phase 2 expansion trial was to determine the efficacy and safety of combination therapy with azacitidine (75 mg/m(2)/d for 5 days) and lenalidomide (10 mg/d for 21 days; 28-day cycle) in patients with higher-risk MDS. Among 36 patients enrolled (18 phase 1, 18 phase 2), median age was 68 years (range, 47-78 years) and follow-up was 12 months (range, 3-55 years). IPSS categories included intermediate-1 (n = 5 patients with excess blasts), intermediate-2 (20), and high (11). Common grade 3/4 nonhematologic adverse events included febrile neutropenia (22% of patients), other infection (11%), pulmonary (11%), cardiac (11%), constitutional (11%), and dermatologic (11%). The overall response rate (per modified MDS International Working Group criteria) was 72%: 16 patients (44%) achieved a complete response (CR), and 10 (28%) had hematologic improvement. Median CR duration was 17+ months (range, 3-39+); median overall survival was 37+ months (range, 7-55+) for CR patients, and 13.6 months for the entire cohort (range, 3-55). TET2/DNMT3A/IDH1/2 mutational status was associated with response in a limited number of patients. The lenalidomide/azacitidine combination is well-tolerated and highly active in treating greater-risk MDS.

The application and biology of immunomodulatory drugs (IMiDs) in cancer

Immunomodulatory drugs (IMiDs) have been used in hematologic malignancies for the last decade. However, the mechanism of action of IMiDs is largely unknown. Here we provide a comprehensive overview of pivotal studies, recent advances in the application of IMiDs in cancer as well as their effects on hematopoietic stem cells including the risk of secondary malignancies. IMiDs have a well-established role as first-line therapy for patients with newly diagnosed and relapsed/refractory multiple myeloma (MM). Variant combinations of IMiDs with other chemotherapy reagents show promising outcomes in MM. Recent concerns on increased rate of secondary cancer in MM patients treated with maintenance lenalidomide were raised. But analysis of maintenance studies showed that the benefit of maintenance outweighs the risk of secondary cancers in MM. IMiDs also show efficacy in myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), Non-Hodgkin's lymphoma (NHL) and myelofibrosis (MF), but not in solid tumors. The major adverse effects are venous thromboembolism, neuropathy and cytopenias. IMiDs induce expansion and self-renewal of CD34+ hematopoietic progenitors and inhibit lineage maturation/differentiation by affecting critical transcription factors which might contribute to myelosuppression effect of IMiDs.

Acute myeloid leukemia: focus on novel therapeutic strategies

Acute myeloid leukemia (AML) is a heterogeneous disease with variable clinical outcomes. Cytogenetic analysis reveals which patients may have favorable risk disease, but 5-year survival in this category is only approximately 60%, with intermediate and poor risk groups faring far worse. Advances in our understanding of the biology of leukemia pathogenesis and prognosis have not been matched with clinical improvements. Unsatisfactory outcomes persist for the majority of patients with AML, particularly the elderly. Novel agents and treatment approaches are needed in the induction, post-remission and relapsed settings. The additions of clofarabine for relapsed or refractory disease and the hypomethylating agents represent recent advances. Clinical trials of FLT3 inhibitors have yielded disappointing results to date, with ongoing collaborations attempting to identify the optimal role for these agents. Potential leukemia stem cell targeted therapies and treatments in the setting of minimal residual disease are also under investigation. In this review, we will discuss recent advances in AML treatment and novel therapeutic strategies.

A phase II study of lenalidomide alone in relapsed/refractory acute myeloid leukemia or high-risk myelodysplastic syndromes with chromosome 5 abnormalities

This phase II study assessed the efficacy and safety of lenalidomide in patients with relapsed/refractory acute myeloid leukemia (N = 18) and high-risk myelodysplastic syndrome (N = 9) with chromosome 5 abnormalities. The overall complete remission rate with or without platelet recovery was 7% (2/27). Activity of lenalidomide was limited to patients with noncomplex cytogenetics.

BACKGROUND

Lenalidomide is effective in low-risk myelodysplastic syndromes (MDS) with deletion 5q. We conducted a phase II study to evaluate the safety and efficacy of lenalidomide in patients with relapsed/refractory acute myeloid leukemia (AML) and high-risk MDS with any chromosome 5 abnormality.

PATIENTS AND METHODS

Eighteen adults with AML and 9 with high-risk MDS were enrolled. Lenalidomide was given orally at doses 5 to 25 mg daily for 21 days of a 28-day cycle until disease progression or unacceptable adverse event.

RESULTS

Median age for all 27 patients was 64 years (range, 39-88 years) with a median of 2 previous therapies (range, 1-6 lines). Two patients (7%) with AML and 5q deletion and +8 cytogenetic abnormality in 2 separate clones achieved complete remission (CR) or CR without platelet recovery (CRp). Response durations were 4 and 6 months, respectively. No responses were seen in patients with chromosome 5 abnormality in a complex cytogenetic background. Twenty patients (74%) developed neutropenic fever or infection requiring hospitalization.

CONCLUSIONS

Clinical activity of lenalidomide as single agent in AML and high-risk MDS with chromosome 5 abnormalities appears to be limited to patients with noncomplex cytogenetics.

Induction and postremission strategies in acute myeloid leukemia: state of the art and future directions

Although the past decade has brought improvements in the treatment of AML, particularly for younger individuals, most patients succumb to the disease. With current induction therapy, most patients achieve remission, but the optimal strategy for post-remission therapy is unclear. Refinements to risk classification systems that incorporate additional molecular markers may better guide physicians in recommendations for postremission therapy. The prognosis for older patients with AML remains uniformly poor, because only a minority can benefit from intensive chemotherapy and novel HCT strategies. Despite active investigation, no standard of care has emerged for patients who are not suitable candidates for standard induction therapy. The development of less toxic, more effective therapies for this population is sorely needed. Advances in molecular genetics, immunology, and the biology of normal and malignant hematopoiesis pathogenesis have led to an improved understanding of the pathogenesis of AML and to the discovery of potential therapeutic targets. Until a greater proportion of individuals with AML attain long-term survival, patients should routinely be referred to cancer centers and enrolled in investigational studies.

Update on immunomodulatory drugs (IMiDs) in hematologic and solid malignancies

INTRODUCTION

Thalidomide and its analogs [small molecule immunomodulatory drugs (IMiDs®)] are among the most successful new therapeutic agents of recent years. Thalidomide is now an integral part of multiple myeloma (MM) therapy. Lenalidomide has been approved for the treatment of patients with relapsed MM and 5q-myelodysplastic syndromes (MDS). Currently, more than 400 clinical trials are evaluating the activity of lenalidomide, alone or in combination with other conventional or novel therapies, in newly diagnosed MM and 5q-MDS. Based on their broad range of actions within the tumor microenvironment, IMiDs are currently also evaluated in a wide variety of additional hematologic and solid malignancies.

AREAS COVERED

This paper reviews the historic development of thalidomide and its derivatives and presents novel insights into their mode of action. Moreover, it discusses up-to-date clinical trials investigating IMiDs and potential future research and therapeutic perspectives in MM and other malignancies.

EXPERT OPINION

Although IMiDs have emerged as powerful agents for the treatment of hematologic and solid tumors, more preclinical and clinical studies are urgently needed both to increase our knowledge of their mechanisms of action, and to optimize their clinical use, in order to further improve the patient's quality of life and survival.

The clinical safety of lenalidomide in multiple myeloma and myelodysplastic syndromes

INTRODUCTION

Lenalidomide is an IMiDs® oral immunomodulatory compound developed for the treatment of patients with multiple myeloma (MM) and myelodysplastic syndromes (MDS). Long-term continuous treatment with lenalidomide beyond first response may be important to optimize responses and delay relapse.

AREAS COVERED

This review summarizes the lenalidomide mechanism of action, pharmacodynamics, key clinical studies with a focus on safety and post-marketing surveillance data. The necessity for early adverse-event management, including dose modifications for neutropenia and thrombocytopenia, and venous thromboembolism prophylaxis, where applicable, in order to maintain patients on treatment and achieve optimal efficacy, is discussed. Secondary primary malignancies in MM and progression to acute myeloid leukemia in MDS patients in the context of lenalidomide treatment are also discussed. Finally, as lenalidomide is renally excreted, the requirement for dose adjustment according to creatinine clearance is discussed.

EXPERT OPINION

Lenalidomide is highly effective and generally well tolerated. Most adverse events occur early during the course of treatment and are manageable. Lenalidomide is not associated with peripheral neuropathy and has a lack of cumulative toxicity, making it an effective treatment option for long-term use in the management of MM and low/intermediate-1-risk MDS, specifically with chromosome 5q deletion with or without other cytogenetic abnormalities.

A multicenter phase II trial of decitabine as first-line treatment for older patients with acute myeloid leukemia judged unfit for induction chemotherapy

BACKGROUND

The treatment of acute myeloid leukemia of older, medically non-fit patients still poses a highly unmet clinical need, and only few large, prospective studies have been performed in this setting. Given the established activity of hypomethylating agents such as 5-aza-2'-deoxycytidine (decitabine) in myelodysplastic syndromes and acute myeloid leukemia with 20-30% bone marrow blasts, we investigated whether this drug is also active in patients with more than 30% blasts.

DESIGN AND METHODS

To evaluate the efficacy and toxicity of decitabine in patients over 60 years old with untreated acute myeloid leukemia ineligible for induction chemotherapy, 227 patients (median age, 72 years), many with comorbidities, adverse cytogenetics and/or preceding myelodysplastic syndrome were treated with this hypomethylating agent. During the initial decitabine treatment (135 mg/m(2) total dose infused intravenously over 72 hours every 6 weeks), a median of two cycles was administered (range, 1-4). All-trans retinoic acid was administered to 100 patients during course 2. Fifty-two patients who completed four cycles of treatment subsequently received a median of five maintenance courses (range, 1-19) with a lower dose of decitabine (20 mg/m(2)) infused over 1 hour on 3 consecutive days every 4-6 weeks.

RESULTS

The complete and partial remission rate was 26%, 95% CI (20%, 32%), and an antileukemic effect was noted in 26% of patients. Response rates did not differ between patients with or without adverse cytogenetics; patients with monosomal karyotypes also responded. The median overall survival from the start of decitabine treatment was 5.5 months (range, 0-57.5+) and the 1-year survival rate was 28%, 95%CI (22%,34%). Toxicities were predominantly hematologic.

CONCLUSIONS

Decitabine is well tolerated by older, medically non-fit patients with acute myeloid leukemia; myelosuppression is the major toxicity. The response rate and overall survival were not adversely influenced by poor-risk cytogenetics or myelodysplastic syndrome. Because of these encouraging results, randomized studies evaluating single-agent decitabine versus conventional treatment are warranted. The study is registered with the German Clinical Trials Registry, number DRKS00000069.

Immunomodulating drugs in myelodysplastic syndromes

Based on immune mechanisms that appear to play an important role in the pathophysiology of at least part of the lower-risk myelodysplastic syndrome (MDS), the immunomodulating drug (IMID) thalidomide and its derivative lenalidomide (LEN) have been used in MDS, principally in lower-risk MDS. LEN has become the first-line US Food and Drug Administration (FDA)-approved treatment for lower-risk MDS with 5q deletion (del5q), in which its main mechanism of action is probably a direct cytotoxic activity on the del5q clone. This possibly specific effect is currently being investigated in higher-risk MDS-and even acute myeloid leukemia (AML)-with del5q, but LEN has also demonstrated some efficacy in MDS and AML without del5q. Thalidomide also has some activity in lower-risk MDS without del5q, but its side effects limit its practical use in these patients.