Lenalidomide in multiple myeloma: current experimental and clinical data

Lenalidomide (LEN) is a structural analogue of Thalidomide and is currently considered a promising compound among immunomodulatory drugs. Following the demonstration of its potent anti-angiogenic, anti-inflammatory, and antineoplastic effects in preclinical models, LEN has emerged as an interesting option for the management of selective hematologic malignancies and may also have a possible role in certain solid tumors as well. It is currently approved in the second-line therapy of multiple myeloma (MM) as well as in myelodysplastic syndrome characterized by 5q minus abnormalities. LEN has been found to be effective in the treatment of both of these conditions and to possess a manageable toxicity profile. In MM, a number of ongoing clinical trials are defining its role in the treatment of newly diagnosed disease as well as in maintenance therapy. Combination approaches pretransplant have shown great promise. Its role in the management of relapsed and refractory disease is now well established. Its long-term tolerability profile appears favorable although an increased risk in new malignancies in patients receiving LEN as maintenance post-stem cell transplant warrants some caution, with follow-up studies being important in determining the long-term implications of this observation.     

SDX-308, a nonsteroidal anti-inflammatory agent, inhibits NF-kappaB activity, resulting in strong inhibition of osteoclast formation/activity and multiple myeloma cell growth

Multiple myeloma is characterized by increased osteoclast activity that results in bone destruction and lytic lesions. With the prolonged overall patient survival achieved by new treatment modalities, additional drugs are required to inhibit bone destruction. We focused on a novel and more potent structural analog of the nonsteroidal anti-inflammatory drug etodolac, known as SDX-308, and its effects on osteoclastogenesis and multiple myeloma cells. SDX-101 is another structural analog of etodolac that is already used in clinical trials for the treatment of B-cell chronic lymphocytic leukemia (B-CLL). Compared with SDX-101, a 10-fold lower concentration of SDX-308 induced potent (60%-80%) inhibition of osteoclast formation, and a 10- to 100-fold lower concentration inhibited multiple myeloma cell proliferation. Bone resorption was completely inhibited by SDX-308, as determined in dentin-based bone resorption assays. SDX-308 decreased constitutive and RANKL-stimulated NF-kappaB activation and osteoclast formation in an osteoclast cellular model, RAW 264.7. SDX-308 effectively suppressed TNF-alpha-induced IKK-gamma and IkappaB-alpha phosphorylation and degradation and subsequent NF-kappaB activation in human multiple myeloma cells. These results indicate that SDX-308 effectively inhibits multiple myeloma cell proliferation and osteoclast activity, potentially by controlling NF-kappaB activation signaling. We propose that SDX-308 is a promising therapeutic candidate to inhibit multiple myeloma growth and osteoclast activity and that it should receive attention for further study.     

Lenalidomide in multiple myeloma

For many years the treatment of multiple myeloma was limited to such regimens as melphalan-prednisone, high-dose dexamethasone, and vincristine-doxorubicin-dexamethasone (VAD). These combinations provided response rates of 45-55%, with complete remission rates of up to 10%. With the advent of thalidomide- and bortezomib-based combinations, response rates to induction therapy have risen to 85-95% in previously untreated patients and are associated with complete remission rates up to 25%. However, these agents are associated with such side-effects as somnolence, constipation and neuropathy. Lenalidomide, a thalidomide analog, was developed with the hope of improving both the efficacy and toxicity profile of thalidomide, and has subsequently shown significant clinical activity in patients with multiple myeloma. We describe the role of lenalidomide in patients with symptomatic multiple myeloma that is newly diagnosed, relapsed and/or refractory to other therapies, or concurrent with primary amyloidosis.     

The future role of thalidomide in multiple myeloma

Treatment for multiple myeloma typically is chemotherapy, high-dose therapy with stem cell transplantation or radiation. Thalidomide shows promise, but to improve knowledge and understanding of this drug, more clinical data is required. Workshops designed to propose new studies providing much needed data on the use of thalidomide as first-line therapy, as maintenance therapy and as treatment for refractory or relapsed disease are reported here. Thalidomide has been shown to be effective in previously untreated patients as monotherapy (36% remission), although greater remission is seen in combination therapy, for example, thalidomide with dexamethasone (72% remission). Thalidomide is an interesting maintenance therapy. It has the advantages of being effective in the bone marrow and having a long-lasting effect but suffers because of its significant side-effect profile; however, it is tolerated by most patients. The adverse effects are thought to be dose-limiting, and most are seen in all patients at the beginning of treatment. Further clinical evidence is needed to determine the effectiveness of thalidomide as maintenance therapy in patients with multiple myeloma, having been shown to be active against refractory multiple myeloma, even in patients who relapse after high-dose chemotherapy. The workshop acknowledged the problems associated with designing a phase III study, and it is clear that many areas need to be addressed in the use of thalidomide for the treatment of multiple myeloma.     

New treatment of multiple myeloma

PURPOSE: After decades of minimal progress, two new classes of drugs with novels mechanisms of action: immunomodulatory drugs (thalidomide and lenalidomide) and proteasome inhibitors (bortezomib) have shown great activity for the treatment of multiple myeloma. CURRENT KNOWLEDGE AND KEY POINTS: Thalidomide acts by a variety of mechanisms; its efficacy is well known in disease relapse especially associated with dexamethasone. Recent results prove that combination of thalidomide with melphalan and prednisone should be considered as the first line standard of care in elderly patient. The main side effects are peripheral neuropathy and deep-vein thrombosis. Bortezomib is the first proteasome inhibitor. It is approved for the treatment in first disease relapse. The combination with glucocorticoids is synergistic. This combination in induction treatment before autologous stem cell transplantation is promising, as well as the combination with melphalan and prednisone in elderly patient. The main toxicities are fatigue and peripheral neuropathy. Lenalidomide is a structural analogue of thalidomide. Its efficacy in combination with dexamethasone has been proved in relapsing patients. The main toxicity is hematologic. Utilisation as first line treatment is also promising. FUTURE PROSPECTS AND PROJECTS: These three drugs have toxicities predictable and manageable and can be used successively or in combination for greater effectiveness. They have an impact on the multiple myeloma treatment strategies and on the disease course itself.     

反应停联合三氧化二砷及维生素C治疗多发性骨髓瘤8例分析

目的观察反应停联合三氧化二砷及维生素C治疗多发性骨髓瘤的疗效及不良反应。方法确诊的多发性骨髓瘤患者8例，使用反应停联合三氧化二砷及维生素C的方案：持续口服小剂量反应停（100mg／d），第1周（d1—5）将As2O3 10mg加入液体静滴，后再以维生素C1000mg加入液体静滴；第2—12周，每周两次As2O3 10mg及维生素C1000mg如前使用。结果部分缓解6例（75％），进步1例（12．5％），总有效率87．5％（7／8）。不良反应有乏力，便秘，恶心、呕吐，肝功能受损，浮肿等。结论反应停联合三氧化二砷及维生素c治疗多发性骨髓瘤疗效明显，患者耐受性可，特另Ⅱ适用于有多种并发症的老年患者。     

Pomalidomide augments fetal hemoglobin production without the myelosuppressive effects of hydroxyurea in transgenic sickle cell mice

Pharmacologic induction of fetal hemoglobin (HbF) expression is an effective treatment strategy for sickle cell disease (SCD) and β-thalassemia. Pomalidomide is a potent structural analog of thalidomide and member of a new class of immunomodulatory drugs. Recent reports demonstrated that pomalidomide reduced or eliminated transfusion requirements in certain hematologic malignancies and induced HbF ex vivo in CD34(+) progenitor cells from healthy and SCD donors. We investigated the effects of pomalidomide on erythropoiesis and hemoglobin synthesis in a transgenic mouse model of SCD. We found that 8 weeks of treatment with pomalidomide induced modest increases of HbF with similar efficacy as hydroxyurea. However, in stark contrast to hydroxyurea's myelosuppressive effects, pomalidomide augmented erythropoiesis and preserved bone marrow function. Surprisingly, combinatory therapy with both drugs failed to mitigate hydroxyurea's myelotoxic effects and caused loss of HbF induction. These findings support further evaluation of pomalidomide as a novel therapy for SCD.     

Thalidomide-induced antiangiogenic action is mediated by ceramide through depletion of VEGF receptors, and is antagonized by sphingosine-1-phosphate

Thalidomide, which is clinically recognized as an efficient therapeutic agent for multiple myeloma, has been thought to exert antiangiogenic action through an unknown mechanism. We here show a novel mechanism of thalidomide-induced antiangiogenesis in zebrafish embryos. Thalidomide induces the defect of major blood vessels, which is demonstrated by their morphologic loss and confirmed by the depletion of vascular endothelial growth factor (VEGF) receptors such as neuropilin-1 and Flk-1. Transient increase of ceramide content through activation of neutral sphingomyelinase (nSMase) precedes thalidomide-induced vascular defect in the embryos. Synthetic cell permeable ceramide, N-acetylsphingosine (C2-ceramide) inhibits embryonic angiogenesis as well as thalidomide. The blockade of ceramide generation by antisense morpholino oligonucleotides for nSMase prevents thalidomide-induced ceramide generation and vascular defect. In contrast to ceramide, sphingosine-1-phosphate (S1P) inhibits nSMase-dependent ceramide generation and restores thalidomide-induced embryonic vascular defect with an increase of expression of VEGF receptors. In human umbilical vein endothelial cells (HUVECs), thalidomide-induced inhibition of cell growth, generation of ceramide through nSMase, and depletion of VEGF receptors are restored to the control levels by pretreatment with S1P. These results suggest that thalidomide-induced antiangiogenic action is regulated by the balance between ceramide and S1P signal.     

The evolving background for high-dose treatment for myeloma

In the constantly evolving field of myeloma, this special issue is slanted towards how the newer targeted treatments fit in with various transplantation strategies. High-dose treatment for myeloma with autologous stem cell transplantation started 25 years ago, with the consequence of producing complete remissions and a doubling of survival. Since then, its role has been refined and it has been accepted as standard treatment. The current challenge is to optimize its use into a background of the development, availability and regulatory approval of newer targeted therapies such as Thalidomide, Revlimid (Lenalidomide) and Velcade (Bortezomib). This special issue addresses these problems, and gives particular emphasis on the attainment of very long-term survival, with normal quality of life for patients with myeloma who do not necessarily need to be cured of their molecular disease, that is, they are 'operationally cured.' It is hoped that the reader will find the information in this issue useful in the day-to-day management of patients and we hope that this will also inspire new research directions designed to improve the outcome of patients with myeloma.     

Efficacy of thalidomide therapy for extramedullary relapse of myeloma following allogeneic transplantation.

Treatment options for patients with myeloma who relapse after allogeneic stem cell transplantation are limited. Thalidomide, an antineoplastic agent, has been shown to be effective in multiple myeloma through proposed mechanisms that may include angiogenesis inhibition. Herein we report successful thalidomide treatment of four patients who relapsed following allogeneic transplantation, three of whom had predominantly extramedullary relapse. Thalidomide was well tolerated in all patients; in two patients interferon-alpha was subsequently added to thalidomide as maintenance therapy without worsening graft-versus-host disease. We suggest that extramedullary myeloma is particularly sensitive to thalidomide, speculating that growth biology may in part be dependent on angiogenesis.     

Pomalidomide plus low-dose dexamethasone in myeloma refractory to both bortezomib and lenalidomide: comparison of 2 dosing strategies in dual-refractory disease

Pomalidomide at doses of 2 or 4 mg/d has demonstrated excellent activity in patients with multiple myeloma (MM). We opened 2 sequential phase 2 trials using the pomalidomide with weekly dexamethasone (Pom/dex) regimen at differing doses to study the efficacy of this regimen in patients who have failed both lenalidomide and bortezomib. Pomalidomide was given orally 2 or 4 mg daily with dexamethasone 40 mg weekly. Thirty-five patients were enrolled in each cohort. Confirmed responses in the 2-mg cohort consisted of very good partial response (VGPR) in 5 (14%), partial response (PR) in 4 (11%), minor response (MR) in 8 (23%) for an overall response rate of 49%. In the 4-mg cohort, confirmed responses consisted of complete response (CR) in 1 (3%), VGPR in 3 (9%), PR in 6 (17%), MR in 5 (14%) for an overall response rate of 43%. Overall survival at 6 months is 78% and 67% in the 2- and 4-mg cohort, respectively. Myelosuppression was the most common toxicity. This nonrandomized data suggests no advantage for 4 mg over the 2 mg daily. Pomalidomide overcomes resistance in myeloma refractory to both lenalidomide and bortezomib. This trial is registered at http://ClinicalTrials.gov, number NCT00558896.     

Development of leukocytoclastic vasculitis in a patient with multiple myeloma during treatment with thalidomide

Thalidomide, an agent with antiangiogenic and immunomodulatory properties, is therapeutically effective in multiple myeloma, leprosy, and autoimmune diseases. The most common clinical toxicities of thalidomide are constipation, neuropathy, fatigue, sedation, rash, tremor, and edema. We here describe for the first time a patient who developed leukocytoclastic vasculitis during therapy with thalidomide. Of the 260 patients treated with thalidomide in our institution, this is the first patient who developed autoimmune disease. We conclude that patients with malignant disorders who are treated with thalidomide should be carefully monitored for the development of autoimmune disorders. Whether autoimmune phenomena also occur during treatment with new drugs such as PS-341 or potent immunomodulatory agents remains to be evaluated.     

Risk of thrombosis with lenalidomide and its prevention with aspirin

Lenalidomide, an analog of thalidomide, is an effective new treatment for multiple myeloma. Both compounds are associated with an increased risk of venous thromboembolism, particularly when used in combination with high-dose dexamethasone. As new trials with lenalidomide are being planned and performed, investigators are placing high importance on reducing the risk of thrombosis by incorporating an antithrombotic agent into the therapeutic regimen. Low-molecular-weight heparin, warfarin, and aspirin have all been suggested as candidate drugs for thromboprophylaxis, but none of these agents have been evaluated in randomized clinical trials. A body of opinion has evolved that aspirin is very effective in preventing venous thrombosis in myeloma patients treated with lenalidomide. If correct, this view has important implications, because aspirin is inexpensive and is safer and more convenient than anticoagulants. On the other hand, aspirin is less effective than anticoagulants for preventing venous thrombosis in other high-risk groups, and therefore might not be the most appropriate choice for preventing of venous thrombosis in myeloma patients. This commentary examines the strength of the evidence supporting the effectiveness of aspirin in preventing venous thrombosis in multiple myeloma patients treated with lenalidomide. It is concluded that the evidence that aspirin is efficacious in preventing venous thrombosis in myeloma patients is based on "before/after" and retrospective studies, with potential for bias and confounders. There is, therefore, a critical need to incorporate a randomized comparison of aspirin with an anticoagulant in future trials evaluating lenalidomide in multiple myeloma.     

Lenalidomide: a synthetic compound with an evolving role in cancer management

Abstract

Lenalidomide is a functional and structural analogue of thalidomide with a relatively benign toxicity profile and pleiotropic anti-tumor activity, exhibiting anti-angiogenic and immunomodulatory effects. Lenalidomide has already been approved for the management of low or intermediate-1 risk myelodysplastic syndrome with chromosome 5q31 deletion and relapsed/refractory multiple myeloma in combination with dexamethasone. During the last five years, multiple clinical trials have been conducted to explore its potential efficacy in hematologic as well as in solid malignancies, revealing a significant benefit in clinical outcomes. This review outlines the mechanisms of action, the toxicity profile and the efficacy of lenalidomide, reviewing the current literature and focusing on the current status of the compound in cancer management. The determination of molecular biomarkers, predictive of clinical response to lenalidomide may reveal a more substantial role of this agent in the treatment of hematologic as well as solid malignancies.     

The potent bisphosphonate ibandronate does not induce myeloma cell apoptosis in a murine model of established multiple myeloma

Bisphosphonates are effective in the management of bone disease in patients with multiple myeloma and recent reports have suggested that they may also have an anti-tumour activity. In support of this, we have previously demonstrated that bisphosphonates can induce myeloma cell apoptosis in vitro; however, it remains unclear whether this occurs in vivo. We have therefore investigated the effect of the potent bisphosphonate ibandronate in the 5T2MM murine model of established multiple myeloma. Short-term treatment with a high dose of ibandronate had no effect on either myeloma cell number or the proportion of myeloma cells undergoing apoptosis. These observations suggest that although bisphosphonates induce apoptosis in myeloma cells in vitro, they may not have the same anti-tumour effects in vivo.     

Therapy with thalidomide in refractory multiple myeloma patients - the revival of an old drug

We have treated 17 refractory or relapsed multiple myeloma patients resistant to chemotherapy with thalidomide at a dose of 200-800 mg/day. Eleven patients responded, five of whom had a very good partial response (> 75% decline in M protein) and another five exhibited a partial response (> 50% decline in M protein). Except for one patient, treatment was well tolerated with only mild side-effects. Thalidomide should be included in the therapeutic options for refractory myeloma.     

Synergistic anti‐myeloma activity of the proteasome inhibitor marizomib and the IMiD® immunomodulatory drug pomalidomide

The proteasome inhibitor bortezomib is an effective therapy for the treatment of relapsed and refractory multiple myeloma (RRMM); however, prolonged treatment can be associated with toxicity, peripheral neuropathy and drug resistance. Our earlier studies showed that the novel proteasome inhibitor marizomib is distinct from bortezomib in its chemical structure, mechanisms of action and effects on proteasomal activities, and that it can overcome bortezomib resistance. Pomalidomide, like lenalidomide, has potent immunomodulatory activity and has been approved by the US Food and Drug Administration for the treatment of RRMM. Here, we demonstrate that combining low concentrations of marizomib with pomalidomide induces synergistic anti‐MM activity. Marizomib plus pomalidomide‐induced apoptosis is associated with: (i) activation of caspase‐8, caspase‐9, caspase‐3 and PARP cleavage, (ii) downregulation of cereblon (CRBN), IRF4, MYC and MCL1, and (iii) suppression of chymotrypsin‐like, caspase‐like, and trypsin‐like proteasome activities. CRBN‐siRNA attenuates marizomib plus pomalidomide‐induced MM cells death. Furthermore, marizomib plus pomalidomide inhibits the migration of MM cells and tumour‐associated angiogenesis, as well as overcomes cytoprotective effects of bone marrow microenvironment. In human MM xenograft model studies, the combination of marizomib and pomalidomide is well tolerated, inhibits tumour growth and prolongs survival. These preclinical studies provide the rationale for on‐going clinical trials of combined marizomib and pomalidomide to improve outcome in patients with RRMM.     

Should prophylactic granulocyte‐colony stimulating factor be used in multiple myeloma patients developing neutropenia under lenalidomide‐based therapy?

Lenalidomide combined with dexamethasone has significant clinical activity in the treatment of multiple myeloma (MM). In previous clinical trials lenalidomide-induced neutropenia was a frequent side-effect, often leading to treatment delays and dose reductions. We describe three MM patients treated with lenalidomide plus dexamethasone, which developed grade 3/4 neutropenia during the initial cycles, but without serious infection. Administration of granulocyte-colony stimulating factor (G-CSF) for 3 d prevented further neutropenia, treatment delays, dose reductions, or infectious complications during the following cycles. Consequently, G-CSF could be effective in preventing further neutropenia-related complications without compromising treatment efficacy in MM patients with lenalidomide-induced neutropenia.     

Pomalidomide in combination with dexamethasone results in synergistic anti‐tumour responses in pre‐clinical models of lenalidomide‐resistant multiple myeloma

Pomalidomide is an IMiD^® immunomodulatory agent, which has shown clinically significant benefits in relapsed and/or refractory multiple myeloma (rrMM) patients when combined with dexamethasone, regardless of refractory status to lenalidomide or bortezomib. (Schey et al, 2004 ; San Miguel et al, 2013; Richardson et al, 2014; Scott, 2014 ) In this work, we present preclinical data showing that the combination of pomalidomide with dexamethasone (PomDex) demonstrates potent anti‐proliferative and pro‐apoptotic activity in both lenalidomide‐sensitive and lenalidomide‐resistant MM cell lines. PomDex also synergistically inhibited tumour growth compared with single‐agent treatment in xenografts of lenalidomide‐resistant H929 R10‐1 cells. Typical hallmarks of IMiD compound activity, including IKZF3 (Aiolos) degradation, and the downregulation of interferon regulatory factor (IRF) 4 and MYC, seen in lenalidomide‐sensitive H929 MM cell lines, were also observed in PomDex‐treated lenalidomide‐resistant H929 MM cells. Remarkably, this resulted in strong, synergistic effects on the induction of apoptosis in both lenalidomide‐sensitive and resistant MM cells. Furthermore, gene expression profiling revealed a unique differential gene expression pattern in PomDex‐treated samples, highlighted by the modulation of pro‐apoptotic pathways in lenalidomide‐resistant cells. These results provide key insights into molecular mechanisms of PomDex in the lenalidomide‐resistant setting.