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.

Low venous thromboembolic risk with bortezomib in multiple myeloma and potential protective effect with thalidomide/lenalidomide-based therapy: review of data from phase 3 trials and studies of novel combination regimens

Patients with multiple myeloma (MM) are at elevated risk of venous thromboembolism (VTE), specifically deep vein thrombosis (DVT) and pulmonary embolism (PE). VTE risk in MM is increased by various patient- and disease-related factors. The type of anti-MM therapy represents a key factor, with a substantially elevated VTE risk in patients treated with the immunomodulatory drugs (IMiDs) thalidomide or lenalidomide in combination with dexamethasone and/or chemotherapy; VTE risk with lenalidomide-dexamethasone is further increased with concomitant erythropoietin. By contrast, treatment with the proteasome inhibitor bortezomib, alone or in combination, does not increase VTE risk; rates of DVT/PE do not appear affected by the use of erythropoiesis-stimulating agents. Bortezomib has shown antihemostatic effects in patients with relapsed or refractory MM, which supports that it exerts antithrombotic actions and thus potentially provides a protective effect in combination with regimens with an elevated VTE risk. Herein, we review data from phase 3 trials of bortezomib- and/or IMiD-based therapy in frontline MM, together with other studies of novel combination regimens. Despite the confounding effect of variable VTE prophylaxis, bortezomib-based regimens were typically associated with DVT/PE rates of ≤5%, similar to those seen with melphalan-prednisone and dexamethasone, whereas IMiD-based bortezomib-free regimens were generally associated with higher rates. Direct comparisons of regimens of thrombogenic potential with or without bortezomib demonstrated lower VTE risk with bortezomib. Between-study comparisons of VTE risk support these findings. Taken together, these data confirm the low VTE risk associated with bortezomib and support a potential protective effect of bortezomib in combination with IMiD-based regimens associated with elevated VTE risk.

Characterization of haematological parameters with bortezomib-melphalan-prednisone versus melphalan-prednisone in newly diagnosed myeloma, with evaluation of long-term outcomes and risk of thromboembolic events with use of erythropoiesis-stimulating agents: analysis of the VISTA trial

Although haematological toxicities, such as anaemia, are common in multiple myeloma (MM), no clear consensus exists on the use and impact of erythropoiesis-stimulating agents (ESA) on outcomes in MM. This analysis characterizes haematological toxicities and associated interventions in the phase III VISTA (Velcade(®) as Initial Standard Therapy in Multiple Myeloma: Assessment with Melphalan and Prednisone) study of bortezomib plus melphalan/prednisone (VMP, n = 344) versus MP (n = 338) in previously untreated MM patients ineligible for high-dose therapy, and evaluates the impact of ESA use or red-blood-cell (RBC) transfusions on outcomes and thromboembolic risk. Incidence of haematological toxicities was similar with VMP and MP; similar rates of interventions and associated complications (e.g. bleeding, febrile neutropenia) were observed. Two hundred thirty three patients received ESA; 204 had RBC transfusions. Frequency of thromboembolic events was low and not affected by ESA use. Median time-to progression (TTP) was similar between ESA/non-ESA [hazard ratio: 1·03 (95% confidence interval 0·76-1·39); P = 0·8478] in both arms (VMP: 19·9/not reached; MP: 15·0/17·5 months). Three-year overall survival (OS) rates were similar between ESA/non-ESA in each arm. Patients receiving RBC transfusions had significantly shorter OS (P < 0·0001) versus non-RBC-transfusion patients. In conclusion, bortezomib did not add to melphalan haematological toxicity. Concomitant ESA use with VMP/MP in previously untreated MM patients did not adversely affect TTP or OS, or increase thromboembolic risk. However, RBC transfusion was associated with significantly shorter survival.

Emerging combination treatment strategies containing novel agents in newly diagnosed multiple myeloma

Treatment strategies for multiple myeloma have changed substantially over the past 10 years following the introduction of bortezomib and the immunomodulatory drugs thalidomide and lenalidomide. In the front-line setting, combination regimens incorporating these novel agents are demonstrating substantial activity, which is translating into improved outcomes compared with previous standards of care. Response rates and depth of response that were previously only seen with high-dose therapy plus stem-cell transplantation (HDT-SCT) can now be achieved with new induction regimens utilizing these novel agents. This has raised the need for trials that will determine the clinical benefit of early SCT in patients that have already achieved a high quality of response. Here, we review the improvements in response and outcome that are seen with these novel-agent regimens, both as induction therapy prior to HDT-SCT and in non-transplant patients, and highlight the latest data from key studies of various novel combinations, including regimens featuring bortezomib plus thalidomide or lenalidomide. We also review data on response and outcomes in patients with poor prognostic characteristics that indicate that the adverse impact typically seen with these factors may be overcome using novel-agent therapy.

New drugs in multiple myeloma

PURPOSE OF REVIEW

Advances in the understanding of multiple myeloma pathogenesis have led to the development of innovative targeted therapies and improved management of this aggressive hematological neoplasia. This review will focus on the clinical trials that have reinforced the use of these new agents. Also, we will briefly take a look at the newer drugs making their way out of the laboratory and into early phase studies.

RECENT FINDINGS

During the past decade new multiple myeloma therapies featuring bortezomib and lenalidomide have come to light, whereas known agents such as thalidomide and arsenic trioxide have been reintroduced as key factors in multiple myeloma management. These new agents and their combinations have shown increased response rates and have added more options for patients with multiple myeloma whose disease has become resistant to conventional therapy. With these drug therapies has come a more targeted approach to treatment enabling not only improved antimyeloma efficacy but also the use of decreased dosing enhancing the safety and tolerability of these regimens. Newer agents including the histone deacetylase, hsp90, mammalian target of rapamycin and Akt inhibitors are showing promise preclinically and are now being assessed in phase I/II trials.

SUMMARY

This new antimultiple myeloma arsenal has shown its worth in both the relapsed/refractory and frontline setting and provides valuable options for patients with this debilitating disease.

Characterisation of haematological profiles and low risk of thromboembolic events with bortezomib in patients with relapsed multiple myeloma

Haematological toxicities and thromboembolic (TE) events are common complications of myeloma therapy. TE risk may be elevated with combination regimens, notably thalidomide/lenalidomide plus high-dose dexamethasone; concomitant erythropoietin appears to further increase the risk with lenalidomide-dexamethasone. We characterised thrombocytopenia and neutropenia in the phase 3 APEX (Assessment of Proteasome Inhibition for Extending Remissions) study of bortezomib versus high-dose dexamethasone in relapsed myeloma, and calculated the incidences of deep-vein thrombosis (DVT)/pulmonary embolism (PE) with: bortezomib or dexamethasone +/- erythropoietin in APEX; bortezomib +/- dexamethasone +/- erythropoietin in two phase 2 studies of relapsed/refractory myeloma. Bortezomib-associated thrombocytopenia and neutropenia were transient, predictable and manageable; mean platelet and neutrophil counts followed a cyclical pattern, and improved over the treatment course. Grade 3/4 thrombocytopenia incidence was higher with bortezomib versus dexamethasone (26%/4% vs. 5%/1%), but significant bleeding events were comparable (4% vs. 5%). DVT/PE incidence was low (< or =3.1%) in all analyses; addition of dexamethasone/erythropoietin did not affect TE risk. In APEX, TE risk appeared lower with bortezomib versus dexamethasone. Bortezomib caused transient and cyclical thrombocytopenia and was not associated with elevated TE risk, alone or with dexamethasone +/- erythropoietin. Preliminary data suggest bortezomib may reduce the thrombogenic potential of combination regimens via inhibition of platelet function or other mechanism-specific effects on coagulation.

Lenalidomide and its role in the management of multiple myeloma

Treatment of multiple myeloma has changed in recent years. Advances in the understanding of the pathogenesis of the disease and the mechanism of drug resistance have led to the development of novel effective biological treatment agents such as thalidomide and bortezomib. Lenalidomide is an oral analogue of thalidomide that lacks the neurotoxic side effects associated with the parent drug, and has shown significant antimyeloma activity. Lenalidomide has now been approved by the US FDA and the European Medicines Agency for use in combination with dexamethasone in patients with at least one prior therapy. Several trials are testing lenalidomide-based regimens in both newly diagnosed and relapsed patients. This review summarizes the profile of lenalidomide and its current role in the treatment of multiple myeloma.

Treatment of plasma cell dyscrasias with lenalidomide

Lenalidomide is an immunomodulatory drug, structurally related to thalidomide, with pleiotropic activity including antiangiogenic and antineoplastic properties. It is the product of advances in our understanding of the biology of myeloma cells, their interactions with the microenvironment and of the underlying molecular pathways. In preclinical and clinical studies, lenalidomide was more potent and less toxic than thalidomide. Subsequent phase II and III studies confirmed the activity of lenalidomide either as a single agent or in combination with dexamethasone in relapsed or refractory myeloma patients, whereas combinations with chemotherapy induce high response rates and durable remissions. Lenalidomide has been used successfully as an upfront treatment either with high or low dose dexamethasone or with melphalan and prednisone, resulting in high overall response and complete response rates and excellent 1-year survival. Lenalidomide causes less neuropathy than thalidomide; however, the risk of thromboembolism is high, especially in patients treated with lenalidomide and steroids. In this review, we summarize the mechanisms of action, toxicity and clinical activity, and the current role of lenalidomide in patients with multiple myeloma or other related plasma cell disorders.

Lenalidomide: a new therapy for multiple myeloma

The last decade has seen rapid evolution in the management of multiple myeloma. Cytogenetic, molecular, and proteomic techniques have led to a better understanding of the pathophysiology and prognostic markers of this heterogeneous malignancy. New immunomodulatory drugs, such as lenalidomide, which interrupt myeloma growth and survival pathways have entered into clinical usage. Combined with dexamethasone, oral lenalidomide has proved to be highly effective in patients whose disease has become resistant to conventional therapy. Currently, several clinical trials are ongoing in order to define the optimal use of this new agent and its combinations across the spectrum of patients with myeloma. Whether the ultimate outcome of future research will be a single-treatment solution for all patients, or whether treatments will become better-tailored to the individual (based on prognostic markers and pre-existing co-morbidities) has yet to be determined.

Lenalidomide in myelodysplastic syndrome and multiple myeloma

The use of thalidomide is limited by adverse effects of sedation, constipation, neuropathy and thromboembolism. In order to discover more potent and less toxic immunomodulators than thalidomide, its chemical structure was modified and lenalidomide was formed. Lenalidomide is approved by the US FDA for the treatment of patients with low-risk myelodysplastic syndrome (MDS) with deletion 5q cytogenetic abnormality. Two studies and a case report have evaluated lenalidomide in these MDS patients and showed significantly higher cytogenetic responses and durable red blood cell transfusion independence. Lenalidomide should be the drug of choice for patients with low and intermediate-1 risk MDS (based on the International Prognostic Scoring System) with chromosome 5q31 deletion with or without other karyotype abnormalities. Lenalidomide, in combination with dexamethasone, has been compared with dexamethasone alone in patients with relapsed or refractory multiple myeloma (MM) in two studies (MM-009 in North America and MM-010 in Europe, Israel and Australia). In these two phase III trials, lenalidomide demonstrated impressive (58-59%) response rates with dexamethasone. Lenalidomide has also been shown to overcome thalidomide resistance in MM patients. Therefore, the lenalidomide plus dexamethasone regimen provides another treatment option, in addition to first line MM treatment regimens of bortezomib, thalidomide or high-dose dexamethasone, for the treatment of relapsed or refractory MM. Lenalidomide does not produce significant sedation, constipation or neuropathy, but does lead to significant myelosuppression, unlike thalidomide. The prescribing information has a black box warning for risk of myelosuppression, deep vein thrombosis/pulmonary embolism and teratogenicity. Administration of lenalidomide is recommended at a starting dose of 10 mg/day orally for deletion 5q in MDS patients. Significant risk of myelosuppression may lead to dose reduction in the majority of these patients. Clinical trials of relapsed and refractory MM have shown that lenalidomide is clinically efficacious at a dosage of 25 mg/day when administered in combination with dexamethasone. Lenalidomide should be continued until disease progression in both MDS and MM patients.

New drugs for myeloma

Although multiple myeloma remains incurable with conventional treatments, management of the disease has recently been transformed with the introduction of three novel agents, bortezomib, thalidomide, and lenalidomide. The proteasome inhibitor bortezomib is approved for the treatment of patients who have received one prior therapy; there is a growing body of clinical evidence showing its effectiveness alone and in combination in the frontline setting, with high response rates and consistently high rates of complete response. Thalidomide plus dexamethasone is approved as frontline treatment of multiple myeloma. Other combination regimens including thalidomide have demonstrated substantial activity in both relapsed and frontline settings. Recently, the thalidomide analogue lenalidomide has been approved, in combination with dexamethasone, for the treatment of patients who have received one prior therapy; this regimen has shown promising results in the frontline setting. These agents represent a new generation of treatments for multiple myeloma that affect both specific intracellular signaling pathways and the tumor microenvironment. Other novel, targeted therapies are also being evaluated in preclinical and clinical studies. Regimens incorporating bortezomib, thalidomide, lenalidomide, and other novel agents, together with commonly used conventional drugs, represent a promising future direction in myeloma treatment. At present, further investigation is required to assess the safety and activity of combinations integrating these other novel agents. However, bortezomib, thalidomide, and lenalidomide are now in widespread clinical use. This review therefore focuses on the extensive clinical data available from studies of these drugs in the treatment of newly diagnosed and advanced multiple myeloma.

Clinical Impact of Bortezomib in Frontline Regimens for Patients with Multiple Myeloma

Standard frontline therapy for multiple myeloma comprises cytoreductive therapy with or without consolidative high-dose therapy plus stem cell transplantation (HDT-SCT). Despite therapeutic advances, the disease remains incurable; most patients relapse following frontline treatment and die within 5 years of diagnosis. New options are required to enhance and prolong response, and improve survival, particularly for elderly patients and those with renal dysfunction. Preclinical studies have demonstrated the ability of bortezomib to enhance the activity of commonly used myeloma agents, an observation validated through clinical studies in both the relapsed and frontline settings. This review focuses on the growing body of clinical evidence showing the effectiveness of bortezomib and bortezomib-based combinations in newly diagnosed patients, characterized by high overall response rates and consistently high rates of complete response. A number of studies incorporating bortezomib as part of induction therapy have demonstrated no adverse impact of bortezomib on stem cell harvest and engraftment in patients proceeding to transplantation. The higher rates of complete response typically associated with bortezomib treatment may potentially improve clinical outcomes in this setting. Final results from ongoing phase III studies of bortezomib-based combinations versus standard regimens will help define the optimal use of bortezomib as a standard component of frontline therapy for multiple myeloma. Disclosure of potential conflicts of interest is found at the end of this article.

Practical considerations in the use of lenalidomide therapy for myelodysplastic syndromes

Lenalidomide has been approved by the US Food and Drug Administration for the treatment of patients with myelodysplastic syndromes (MDS) with an interstitial deletion of the long arm of chromosome 5 and, more recently, in combination with dexamethasone for multiple myeloma in patients who received at least one prior therapy. This discussion examines several clinically relevant, practical considerations regarding dosing, monitoring, follow-up evaluation, adverse events, and available support for lenalidomide recipients and their prescribing physicians in the MDS setting.