Thalidomide and CC-5013 in multiple myeloma: the University of Arkansas experience

Overview of drug therapy for multiple myeloma

Background. Multiple myeloma accounts for 10% of all haematologic malignancies worldwide. In Europe, over 10 000 new cases and nearly 8000 deaths were attributed to multiple myeloma in 2000. Unlike other malignancies, in which surgery and radiation are important treatment modalities, myeloma is exclusively treated with stem cell transplantation and drug therapy, requiring pharmacists to stay abreast of new developments. The melphalan-prednisolone and vincristine-doxorubicin-dexamethasone (VAD) regimens, which have been standard treatments for multiple myeloma over the past few decades, have yielded responses without real survival benefits. Transplantation utilizing high-dose chemotherapy has produced the only meaningful survival benefits for patients with multiple myeloma, but many patients are not candidates for this aggressive treatment option. More effective therapies for multiple myeloma are needed.

Objective. To address the mechanisms of action, safety, and efficacy of novel approaches to the treatment of myeloma involving bortezomib, thalidomide and its analogues, lenalidomide and CC-4047 (ActimidTM), and arsenic trioxide as single agents or in combination regimens.

Data sources. Published preclinical and primary clinical trial results, as well as scientific or clinical meeting abstracts. The author determined the relevance and subsequent inclusion of the data.

Conclusions. Bortezomib is approved in the US and Europe as single-agent therapy for the treatment of relapsed or refractory multiple myeloma. Thalidomide, its analogues, and arsenic trioxide have demonstrated activity and are under investigation in this disease. Further clinical trials of the efficacy and toxicity of these novel agents are ongoing and will further define optimal combinations and sequencing with conventional therapies.

Gain(1)(q21) is an unfavorable genetic prognostic factor for patients with relapsed multiple myeloma treated with thalidomide but not for those treated with bortezomib

Chromosomal aberrations are important prognostic factors in multiple myeloma diagnosis. We evaluated the effect common high-risk chromosomal aberrations in a cohort of 102 patients with relapsed disease treated with bortezomib or thalidomide. Our results showed that patients treated with thalidomide with a gain(1)(q21) had inferior survival compared with the bortezomib group. Therefore, bortezomib-based regiments are more effective for patients with relapsed multiple myeloma with an incidence of gain in the gain(1)(q21).

BACKGROUND

Prognostic impact of specific chromosomal aberrations in patients with relapsed multiple myeloma (MM) treated with the novel agents is briefly described.

PATIENTS AND METHODS

We analyzed the prognostic value of an extended panel of chromosomal aberrations [del(13)(q14), del(17)(p13), t(4;14)(p16;q32), gain(1)(q21), and hyperdiploidy] by using the technique of interphase fluorescence in situ hybridization in a cohort of 102 patients with relapsed MM treated with thalidomide- or bortezomib-based protocols.

RESULTS

The gain(1)(q21) had a negative impact on overall survival for patients with MM treated with thalidomide (15.7 vs. 41.3 months; P = .004). Moreover, we confirmed the negative impact of the cumulative effect of 2 or more cytogenetic changes that occur simultaneously on the overall survival in the thalidomide group (20.3 months vs. not yet reached; P = .039). We did not find any significant impact of the aberrations studied on overall survival in the bortezomib cohort of patients.

CONCLUSION

We conclude that bortezomib-based protocols are able to partially overcome the negative prognostic impact of the tested chromosomal abnormalities in patients with relapsed MM.

miR-29b sensitizes multiple myeloma cells to bortezomib-induced apoptosis through the activation of a feedback loop with the transcription factor Sp1

MicroRNAs (miRNAs) with tumor-suppressor potential might have therapeutic applications in multiple myeloma (MM) through the modulation of still undiscovered molecular pathways. Here, we investigated the effects of enforced expression of miR-29b on the apoptotic occurrence in MM and highlighted its role in the context of a new transcriptional loop that is finely tuned by the proteasome inhibitor bortezomib. In details, in vitro growth inhibition and apoptosis of MM cells was induced by either transient expression of synthetic miR-29b or its stable lentivirus-enforced expression. We identified Sp1, a transcription factor endowed with oncogenic activity, as a negative regulator of miR-29b expression in MM cells. Since Sp1 expression and functions are regulated via the 26S proteasome, we investigated the effects of bortezomib on miR-29b-Sp1 loop, showing that miR-29b levels were indeed upregulated by the drug. At the same time, the bortezomib/miR-29b combination produced significant pro-apoptotic effects. We also demonstrated that the PI3K/AKT pathway plays a major role in the regulation of miR-29b-Sp1 loop and induction of apoptosis in MM cells. Finally, MM xenografts constitutively expressing miR-29b showed significant reduction of their tumorigenic potential. Our findings indicate that miR-29b is involved in a regulatory loop amenable of pharmacologic intervention and modulates the anti-MM activity of bortezomib in MM cells.

Chronic lymphocytic leukemia: treatment options for patients with refractory disease

Patients with purine analogue-refractory chronic lymphocytic leukemia (CLL) have short survival and limited treatment options. Defining the best salvage strategies for this population is challenging, because limited data are available from clinical trials, and because studies have enrolled mixed populations (patients with recurrent and refractory disease or patients with refractory disease and Richter transformation). Moreover, patients with refractory CLL have a high incidence of unfavorable molecular and clinical features, such as high-risk genomic profiles, unmutated immunoglobulin heavy-chain genes, expression of zeta-chain-associated protein kinase 70, and bulky lymphadenopathies. These patients are also severely immunosuppressed because of the underlying disease and the treatments received, and experience a high rate of infectious complications that pose an additional difficulty in selecting treatment. Despite these challenges, in parallel with better characterizations of the biologic features of refractory CLL, the number of available treatment modalities for this population has increased. Several chemoimmunotherapy combinations have been developed, and novel agents with a different mechanism of action are being investigated in clinical trials. Furthermore, allogeneic stem cell transplantation with nonmyeloablative conditioning regimens is a therapeutic strategy that is increasingly offered to patients with refractory CLL.

Phase I study of oral lenalidomide in patients with refractory metastatic cancer

Objectives of this study were to determine the maximum tolerated dose and to characterize the side effect profile and pharmacokinetics of lenalidomide in patients with advanced refractory solid tumors. Patients were treated on a modified Fibronacci dose escalation scheme with an oral daily dose of lenalidomide. A total of 45 patients with 8 different tumor types were accrued. Doses administered included 5, 10, and 20 mg continuous daily doses, every 28 days (n = 15), later modified to intermittent doses of 15, 20, 25, 30, 35, and 40 mg, with a 21 days-on and 7 days-off schedule, due to observed side effects. Lenalidomide exhibited a linear pharmacokinetics over a wide range of doses with the mean half-life of 3.9 hours. The renal function affected lenalidomide clearance, resulting in 50% reduction in patients with mild renal impairment compared with patients with normal function (CL/F = 243 mL/min). Stable disease was documented in 12 of 44 evaluable patients, of whom 9 patients had prostate cancer. Most frequent grade 1 and 2 toxicities included fatigue, nausea, pruritus/rash, neutropenia, and neuropathy. Grade 3/4 events were predominantly hematologic. Lenalidomide was well tolerated up to a 35-mg/d intermittent dosing schedule at doses higher than previously indicated for hematologic malignancies.

Treatment of relapsed/refractory multiple myeloma

The introduction of several novel and active treatments and improvements in supportive care of myeloma patients has resulted in a prolongation of the survival of these patients. However, myeloma remains an incurable disease and almost all patients will relapse. Effective management of the relapsing/refractory disease incorporates several different strategies, depending on prior treatments, responses, and duration of responses, as well as residual toxicity, age, and physical condition. High-dose dexamethasone still has a role in the management of disease complications such as cytopenias, renal impairment, or spinal cord compression until another agent is added. High-dose therapy may be considered for selected patients who have a long-term treatment-free interval after their first transplantation. Allogeneic transplantation is limited to selected young patients, preferably with an HLA-matched donor. However, the backbone of current strategies for the management of relapsed/refractory myeloma includes the novel agents thalidomide, bortezomib, and lenalidomide. These agents, either with dexamethasone or in combination with chemotherapy, have shown significant activity both in relapsed and in refractory patients. Based on the results of phase III trials, lenalidomide and bortezomib have increased the post-relapse survival and are active in patients who have received prior novel agents; lenalidomide is active in thalidomide-pretreated or bortezomib-pretreated patients and bortezomib alone or in combination with chemotherapy is active in thalidomide/lenalidomide-pretreated patients. Combinations of novel agents show synergistic activity and may overcome drug resistance. Finally, special consideration is needed for the management of patients with renal impairment or other poor prognostic features.

In vivo anti-myeloma activity and modulation of gene expression profile induced by valproic acid, a histone deacetylase inhibitor

Valproic acid (VPA) is a well-tolerated anticonvulsant that exerts anti-tumour activity as a histone deacetylase inhibitor. This study investigated the in vitro and in vivo activity of VPA against multiple myeloma (MM) cells. In vitro exposure of interleukin-6-dependent or -independent MM cells to VPA inhibited cell proliferation in a time- and dose-dependent manner and induced apoptosis. In a cohort of severe combined immunodeficiency mice bearing human MM xenografts, VPA induced tumour growth inhibition and survival advantage in treated animals versus controls. Flow cytometric analysis performed on MM cells from excised tumours showed increase of G(0)-G(1) and a decreased G(2)/M- and S-phase following VPA treatment, indicating in vivo effects of VPA on cell cycle regulation. Gene expression profiling of MM cells exposed to VPA showed downregulation of genes involved in cell cycle progression, DNA replication and transcription, as well as upregulation of genes implicated in apoptosis and chemokine pathways. Pathfinder analysis of gene array data identified cell growth, cell cycle, cell death, as well as DNA replication and repair as the most important signalling networks modulated by VPA. Taken together, our data provide the preclinical rationale for VPA clinical evaluation as a single agent or in combination, to improve patient outcome in MM.

Targeting the UPS as therapy in multiple myeloma

The coordinated regulation of cellular protein synthesis and degradation is essential for normal cellular functioning. The ubiquitin proteasome system mediates the intracellular protein degradation that is required for normal cellular homeostasis. The 26S proteasome is a multi-enzyme protease that degrades redundant proteins; conversely, inhibition of proteasomal degradation results in intracellular aggregation of unwanted proteins and cell death. This observation led to the development of proteasome inhibitors as therapeutics for use in cancer. The clinical applicability of targeting proteasomes is exemplified by the recent FDA approval of the first proteasome inhibitor, bortezomib, for the treatment of relapsed/refractory multiple myeloma. Although bortezomib represents a major advance in the treatment of this disease, it can be associated with toxicity and the development of drug resistance. Importantly, extensive preclinical studies suggest that combination therapies can both circumvent drug resistance and reduce toxicity. In addition, promising novel proteasome inhibitors, which are distinct from bortezomib, and exhibit equipotent anti-multiple myeloma activities, are undergoing clinical evaluation in order to improve patient outcome in multiple myeloma. PUBLICATION HISTORY : Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).

Multiple myeloma--an update on diagnosis and treatment

Multiple myeloma is a plasma cell (PC) malignancy characterized by the accumulation of monoclonal PCs in the bone marrow and the production of large amounts of a monoclonal immunoglobulin or paraprotein. In the past years, new approaches in the diagnosis and treatment were introduced aiming to identify high-risk patients who need proper anti-myeloma treatment. Intensive therapy including autologous hematopoietic stem cell transplantation and the new agents bortezomib, thalidomide, and lenalidomide have improved patients' responses. Further optimalization of the different treatment schedules in well-defined patient groups may prolong their survival. Patient stratification is currently based on patient characteristics, extent of myeloma disease, and associated cytogenetic and laboratory anomalies. More and more gene expression studies are introduced to stratify patients and to individualize therapy.

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.

Management of relapsed and relapsed refractory myeloma

Studies of bortezomib, thalidomide, and lenalidomide have shown promising clinical activity in relapsed/refractory multiple myeloma (MM). Bortezomib alone and in combination with other agents is associated with high response rates, consistently high rates of complete response, and a predictable and manageable profile of adverse events. Thalidomide-based regimens have also shown substantial clinical activity. The accumulating experience from ongoing trials of bortezomib/lenalidomide/dexamethasone combinations in patients who have relapsed/refractory or newly diagnosed MM will provide critical information that will determine the possible role of this combination as the basic backbone for combination regimens for management of advanced MM.

Biological pathways and in vivo antitumor activity induced by Atiprimod in myeloma

Atiprimod (Atip) is a novel oral agent with anti-inflammatory properties. Although its in vitro activity and effects on signaling in multiple myeloma (MM) have been previously reported, here we investigated its molecular and in vivo effects in MM. Gene expression analysis of MM cells identified downregulation of genes involved in adhesion, cell-signaling, cell cycle and bone morphogenetic protein (BMP) pathways and upregulation of genes implicated in apoptosis and bone development, following Atip treatment. The pathway analysis identified integrin, TGF-beta and FGF signaling as well as Wnt/beta-catenin, IGF1 and cell-cycle regulation networks as being most modulated by Atip treatment. We further evaluated its in vivo activity in three mouse models. The subcutaneous model confirmed its in vivo activity and established its dose; the SCID-hu model using INA-6 cells, confirmed its ability to overcome the protective effects of BM milieu; and the SCID-hu model using primary MM cells reconfirmed its activity in a model closest to human disease. Finally, we observed reduced number of osteoclasts and modulation of genes related to BMP pathways. Taken together, these data demonstrate the in vitro and in vivo antitumor activity of Atip, delineate potential molecular targets triggered by this agent, and provide a preclinical rational for its clinical evaluation in MM.

The effect of novel anti-myeloma agents on bone metabolism of patients with multiple myeloma

Immunomodulatory drugs (IMiDs) and bortezomib have been recently used in the management of patients with both newly diagnosed and relapsed/refractory multiple myeloma. Except of their direct anti-myeloma effect, these agents also alter the interactions between myeloma cells and marrow microenvironment. Several recent studies have investigated their potential effect on myeloma bone disease. Preclinical studies have demonstrated that IMiDs reduce osteoclast formation and function in vitro. Clinical studies have confirmed that thalidomide reduces markers of bone resorption, while lenalidomide induces osteoclast arrest in myeloma patients. However, IMiDs seem to have no effect on osteoblast exhaustion present in myeloma. The proteasome inhibitor bortezomib restores abnormal bone remodeling through the inhibition of osteoclast function and the increase in osteoblast differentiation and activity in vitro. In myeloma patients, bortezomib reduces biochemical markers of bone resorption and normalizes the RANKL/osteoprotegerin ratio, while at the same time increases bone formation markers reducing levels of dickkopf-1 protein. Whether these effects are direct and not only a consequence of the agents' antimyeloma activity is not totally clear. This review summarizes all available data for these attractive agents that combine potent anti-myeloma activity with beneficial effects on bone and may alter the way of management of myeloma-related bone disease.

The evolving role of lenalidomide in the treatment of hematologic malignancies

Lenalidomide is an immunomodulatory drug, structurally related to thalidomide, which has pleotropic activity, including antiangiogenic and antineoplastic properties. This agent is the product of advances in the understanding of the biology of neoplastic cells, their interaction with the microenvironment and of the underlying molecular pathways. Lenalidomide has shown significant activity in refractory/resistant multiple myeloma, and further studies have shown its activity in other hematologic malignancies with some very encouraging results, especially in subsets of patients with myelodysplastic syndromes. This article reviews the data on lenalidomide use in patients with multiple myeloma, as well as in myelodysplastic syndromes, chronic lymphocytic leukemia and myelofibrosis with myeloid metaplasia.

Clinical efficacy of lenalidomide in patients with relapsed or refractory chronic lymphocytic leukemia: results of a phase II study

PURPOSE

Patients with relapsed or refractory chronic lymphocytic leukemia (CLL) have profound immune defects and limited treatment options. Given the dramatic activity of lenalidomide in other B-cell malignancies and its pleotropic immunomodulatory effects, we conducted a phase II trial of this agent in CLL.

PATIENTS AND METHODS

Patients with relapsed or refractory B-cell CLL (B-CLL) were eligible if they required treatment as per the National Cancer Institute Working Group 1996 guidelines. Lenalidomide was administered orally at 25 mg on days 1 through 21 of a 28-day cycle. Response was assessed after each cycle. Patients were to continue treatment until disease progression, unacceptable toxicity, or complete remission. Rituximab was added to lenalidomide on disease progression.

RESULTS

Forty-five patients were enrolled, with a median age of 64 years. Sixty-four percent of the patients had Rai stage III or IV disease, and 51% were refractory to fludarabine. The overall response rate was 47%, with 9% of the patients attaining a complete remission. Fatigue, thrombocytopenia, and neutropenia were the most common adverse effects noted in 83%, 78%, and 78% of the patients, respectively.

CONCLUSION

Lenalidomide is clinically active in patients with relapsed or refractory B-CLL. These findings are encouraging and warrant further investigation of this agent in the treatment of this disorder.

Clinical implications of chromosomal abnormalities in multiple myeloma

The adverse prognostic role of cytogenetic abnormalities has recently been established in plasma cell dyscrasias. Modern techniques such as fluorescence in situ hybridization and comparative genomic hybridization have revealed a higher incidence of cytogenetic abnormalities in patients with multiple myeloma (MM) compared to conventional cytogenetics. Hypodiploidy and chromosome 13 abnormalities are found in more than 50% of myeloma patients, representing well known factors with adverse prognosis. Rearrangements involving the switch regions of immunoglobulin heavy chain (IgH) gene at 14q32 with various partner genes represent the most common structural abnormalities, having an incidence of 70% in MM. Structural abnormalities of chromosomes 17 and 8 involving the p53 and c-myc genes are considered to be less frequent events, but carry a poor prognosis. New therapeutic approaches such as non-myeloablative allotransplantation and modern therapeutic agents (thalidomide, lenalidomide, and bortezomib) and their combinations give promise for an improved therapeutic management of patients with MM. The detection of t(4;14), t(14;16), deletion of chromosome 13 on metaphase analysis, or deletion of p53 by FISH will define high-risk prognostic groups that are not generally controlled with high-dose melphalan and autologous stem cell transplantation (ASCT), and should therefore be treated with more investigational therapies. Alternatively, eligible patients who do not have these poor risk factors are more likely to benefit from a high-dose, melphalan-based, regimen followed by ASCT.

The activity of lenalidomide with or without dexamethasone in patients with primary systemic amyloidosis

Primary systemic amyloidosis (AL) is an incurable plasma cell disorder. Lenalidomide, especially in conjunction with dexamethasone, is highly active in patients with multiple myeloma. We studied the toxicity and efficacy of lenalidomide in patients with AL. Patients with symptomatic AL, a measurable plasma cell disorder, and adequate hematologic and renal reserve were eligible. Patients received single-agent lenalidomide. If there was no evidence of progression after 3 months or of hematologic response after 3 cycles, dexamethasone was added. Twenty-three patients were enrolled. Thirteen were previously treated. Organ involvement was cardiac (64%), renal (73%), hepatic (23%), and nerve (14%). Within the first 3 cycles of therapy, 10 patients discontinued treatment: 4 early deaths, 3 adverse events, and 3 other causes. With a median follow-up of 17 months, 10 patients responded to treatment. In these patients, responses included 9 hematologic, 4 renal, 2 cardiac, and 2 hepatic. All but one of the responders had dexamethasone added to their treatment program. The most common grade 3 or 4 adverse events at least possibly attributable to lenalidomide were neutropenia (45%), thrombocytopenia (27%), rash (18%), and fatigue (18%). In AL patients, we saw limited activity of single-agent lenalidomide, but significant activity of the combination with dexamethasone, which warrants further investigation.

State of the art chemotherapeutic management of pediatric brain tumors

CNS tumors are the most common solid tumor of childhood. This article will review current treatments for pediatric brain tumors; low-grade gliomas, high-grade gliomas, medulloblastomas and ependymomas. It will also highlight the treatments that are used for brain tumors in very young children and in children with recurrent brain tumors. The management of recurrent pediatric brain tumors unresponsive to standard therapy will be discussed. The agents used in this setting are mainly biological modifiers, which attempt to provide molecularly targeted therapy. Future directions of therapy for pediatric brain tumors are described. Future treatment paradigms will need to consider examining the use of multiple biological modifiers. Similarly, these agents will need to be examined in combination with cytotoxic chemotherapy. Finally, the future direction of pediatric neuro-oncology and the focus of the field as it battles pediatric brain tumors is discussed.

The molecular classification of multiple myeloma

To better define the molecular basis of multiple myeloma (MM), we performed unsupervised hierarchic clustering of mRNA expression profiles in CD138-enriched plasma cells from 414 newly diagnosed patients who went on to receive high-dose therapy and tandem stem cell transplants. Seven disease subtypes were validated that were strongly influenced by known genetic lesions, such as c-MAF- and MAFB-, CCND1- and CCND3-, and MMSET-activating translocations and hyperdiploidy. Indicative of the deregulation of common pathways by gene orthologs, common gene signatures were observed in cases with c-MAF and MAFB activation and CCND1 and CCND3 activation, the latter consisting of 2 subgroups, one characterized by expression of the early B-cell markers CD20 and PAX5. A low incidence of focal bone disease distinguished one and increased expression of proliferation-associated genes of another novel subgroup. Comprising varying fractions of each of the other 6 subgroups, the proliferation subgroup dominated at relapse, suggesting that this signature is linked to disease progression. Proliferation and MMSET-spike groups were characterized by significant overexpression of genes mapping to chromosome 1q, and both exhibited a poor prognosis relative to the other groups. A subset of cases with a predominating myeloid gene expression signature, excluded from the profiling analyses, had more favorable baseline characteristics and superior prognosis to those lacking this signature.

Autologous stem cell transplantation followed by consolidation chemotherapy for patients with multiple myeloma

Although high-dose therapy and autologous stem cell transplant (ASCT) is superior to conventional chemotherapy for treatment of myeloma, most patients relapse and the time to relapse depends upon the initial prognostic factors. The administration of non-cross-resistant chemotherapies during the post-transplant period may delay or prevent relapse. We prospectively studied the role of consolidation chemotherapy (CC) after single autologous peripheral blood stem cell transplant (auto-PBSCT) in 103 mostly newly diagnosed myeloma patients (67 patients were < or =6 months from the initial treatment). Patients received conditioning with BCNU, melphalan+/-gemcitabine and auto-PBSCT followed by two cycles of the DCEP+/-G regimen (dexamethasone, cyclophosphamide, etoposide, cisplatin+/-gemcitabine) at 3 and 9 months post-transplant and alternating with two cycles of DPP regimen (dexamethasone, cisplatin, paclitaxel) at 6 and 12 months post-transplant. With a median follow-up of 61.2 months, the median event-free survival (EFS) and overall survival (OS) are 26 and 54.1 months, respectively. The 5-year EFS and OS are 23.1 and 42.5%, respectively. Overall, 51 (49.5%) patients finished all CC, suggesting that a major limitation of this approach is an inability to deliver all planned treatments. In order to improve results following autotransplantation, novel agents or immunologic approaches should be studied in the post-transplant setting.

The treatment of high grade gliomas and diffuse intrinsic pontine tumors of childhood and adolescence: a historical - and futuristic - perspective

Pediatric high grade gliomas represent a heterogeneous group of tumors with poor prognoses despite the use of multimodal treatment. Very little progress has been made over the past decades in identifying efficacious therapeutic modalities against both high grade gliomas and diffuse brainstem gliomas in children. The degree of surgical resection is the most important clinical prognostic factor for children with high grade gliomas, and a complete resection should be attempted whenever feasible. The role of radiation therapy in the treatment of older children with high grade gliomas and diffuse brain stem gliomas is undisputed; however the benefit of using radiation for patients less than 6 years of age (with high grade gliomas) might be questionable. Despite the absence of solid evidence to support its use, chemotherapy is routinely used against these tumors. Currently temozolomide is being investigated due to its activity in adult trials and based on preliminary data regarding recurrent disease. A small subgroup of patients can be successfully treated with high dose chemotherapy followed by autologous stem cell rescue. Early trials using this modality in the past had been associated with high morbidity and mortality. High dose chemotherapy with autologous stem cell rescue in selected patients with minimal residual disease, angiogenesis inhibitors, radiosensitizers and other biological modifiers are being currently investigated in phase I/II trials.

Thalidomide in multiple myeloma

Multiple myeloma is an incurable bone marrow cancer, the treatment of which is notoriously difficult. Only modest advances have been achieved using complex polychemotherapeutic regimens, transplant strategies and supportive therapy. In 1999, when new drugs for myeloma were urgently needed, thalidomide was introduced and opened up a completely new line of therapy for the disease. Although the mechanism of action is not yet completely understood, thalidomide has demonstrated efficacy in patients with refractory, relapsed myeloma, even in late-stage cases. This article reviews the current knowledge of thalidomide in myeloma treatment, focusing especially on the possible mechanisms of action, clinical results and adverse events of this drug.

Management of the Relapsed/Refractory Myeloma Patient: Strategies Incorporating Lenalidomide

The immunomodulatory drug (IMiD) lenalidomide is a more potent immunomodulator than thalidomide with respect to its effects on cytokine modulation and increased T-cell proliferation. Of all the IMiDs, clinical trial data are most mature for lenalidomide. In phase I studies, dose-limiting toxicities of lenalidomide were limited to myelosuppression and a response rate of 72% was seen in relapsed/refractory patients. Three phase II studies subsequently evaluated the efficacy of single-agent lenalidomide or lenalidomide in combination with dexamethasone. As a single agent for post-transplant salvage therapy, lenalidomide 25 mg every 3 weeks has shown response rates as high as 44%. For patients with relapsed/refractory multiple myeloma, the MM-007 study has shown that lenalidomide alone or in combination with dexamethasone provides response rates between 37% and 41%. In MM-007, median progression-free survival was 5.5 months at early analysis and the median overall survival has yet to be reached. Preliminary data for the single-arm, multicenter, open-label MM-014 study showed that median time to progression was 5.6 months. Response rates indicate that 70% of patients had stable disease or better as the best response to treatment. Two randomized, phase III trials (MM-009 and MM-010) evaluated lenalidomide with high-dose dexamethasone versus high-dose dexamethasone alone for the treatment of relapsed/refractory multiple myeloma. Both MM-009 and MM-010 provided remarkably similar response rates for patients receiving lenalidomide and dexamethasone. In both trials response rates with the combination were greater than twice the response rates seen with high-dose dexamethasone alone. Indeed, an independent Data Monitoring Committee determined that both trials exceeded the prespecified efficacy value of P<.0015, recommending that the trials be discontinued and that lenalidomide be offered to patients on the dexamethasone arm of the trial if clinically indicated. Toxicities observed in studies of lenalidomide alone were low; the incidence of peripheral neuropathy was significantly lower than those noted in trials using thalidomide. Thrombocytopenia was a significant grade 3 or 4 toxicity observed; however, it was manageable with dose reduction. In contrast with high-dose dexamethasone, deep vein thrombosis has emerged as an important toxicity. Lenalidomide is currently being tested in combination with both standard and novel agents, including bortezomib, for patients with relapsed/refractory multiple myeloma.

Treatment of myeloma in patients not eligible for transplantation

Multiple myeloma (MM) remains an incurable disease for most patients, with a median survival of 4 to 5 years. High-dose chemotherapy followed by transplantation has resulted in improvement in response rates and survival compared with conventional therapy, but relapse is nearly universal and not all patients are candidates for this option of aggressive treatment. Standard therapeutic strategies for newly diagnosed patients not eligible for transplantation include pulsed high-dose dexamethasone, melphalan with prednisone, and vincristine in combination with doxorubicin and dexamethasone, as well as other combinations of alkylating agents. Emerging therapies under clinical investigation for first-line therapy include thalidomide, the thalidomide analog lenalidomide, and the proteasome inhibitor bortezomib alone and in combination with other agents, particularly dexamethasone. At an interim analysis, thalidomide combined with melphalan and prednisone was shown to induce a complete or near complete remission (CR) rate of 28% and overall (complete+partial) response rate of 77% in elderly patients generally not eligible for transplantation. These results are comparable to those obtained with high-dose therapy and may obviate transplantation in these patients. Induction therapy with bortezomib-based combinations induces complete and near complete remissions in a similar proportion of patients. These regimens include bortezomib and dexamethasone alone and in combination with doxorubicin, thalidomide, or melphalan. Use of thalidomide or bortezomib does not preclude stem cell harvest. Survival benefits need to be firmly established before these novel regimens emerge as the new standard of care for newly diagnosed disease. However, front-line treatment with combinations involving these agents is a promising strategy that may improve the standard of care for patients both eligible and ineligible for stem cell transplantation.

Thalidomide and immunomodulatory drugs in the treatment of cancer

Thalidomide has antiangiogenic and immunomodulatory properties and has recently been used in the management of human malignancies. Multiple studies have confirmed its activity in multiple myeloma, alone or combined with dexamethasone and/or chemotherapy as first- or second-line treatment. In addition, it may reduce the need for transfusions in patients with myelofibrosis or myelodysplastic syndromes. The activity of thalidomide in solid tumours is less prominent. The most promising results have been reported in Kaposi's sarcoma, malignant melanoma and prostate cancer, especially when it is combined with chemotherapy. Recently, thalidomide analogues (immunomodulatory drugs), with higher immunomodulatory activity and different toxicity profile, have been developed. They have already shown promising activity in multiple myeloma and are currently being evaluated in clinical studies.

New approaches in the treatment of myelofibrosis

Myelofibrosis with myeloid metaplasia (MMM) is a chronic clonal neoangiogenesis disorder characterized by bone marrow fibrosis and neoangiogensis with extramedullary hematopoiesis. Identification of prognostic factors associated with MMM have not impacted the treatment of the disease, which continues to be palliative with the exception of allogeneic stem cell transplantation (SCT) for potential long-term disease-free survival in selected patients. Additional insights into the pathophysiology of MMM have resulted in the use of novel therapeutic strategies in the treatment of this disease. The rationale for the investigation of these agents in MMM and the status of clinical trials with various modalities such as angiogenesis inhibitors (e.g., thalidomide), tyrosine kinase inhibitors (e.g., imatinib mesylate), farnesyl transferase inhibitors (e.g., R115777), and other agents are reviewed, in addition to the potential roles of autologous and allogeneic SCT.