Immunotherapy of multiple myeloma: the start of a long and tortuous journey

The field of tumor immunotherapy is still in its infancy. It is becoming clear that the human immune response is the result of highly complex, continuously evolving interactions between cells of the adaptive and innate arms of the immune system, the internal and external environments, and normal and abnormal cells (e.g., myeloma plasma cells). Despite the considerable advances in our knowledge over the past 30 years, we have still only scratched the surface of the immune system's interaction with malignant diseases such as myeloma and to date, this has not translated into significantly better outcomes for patients with this disease. This review will summarize our current knowledge of the fundamental immunology of myeloma, review immunotherapy trials reported to date and discuss whether, in light of the current information, immunotherapy of multiple myeloma is an achievable goal.

Novel agents in the frontline management of multiple myeloma

Significant advances in our understanding of the biology of multiple myeloma have led to exciting new opportunities in treatment. The management of this disease is rapidly changing with a plethora of clinical trials initiated with novel agents, namely thalidomide, lenalidomide and bortezomib, either alone or in conjunction with established modalities such as conventional cytotoxic agents and stem-cell transplantation. The combination of these novel agents together with conventional regimens have led to higher response rates and survival, providing options for patients whose disease is otherwise resistant to conventional therapy. These pivotal trials that lead to the approval of these three novel agents in treatment naïve patients. The potential implications in the frontline treatment paradigm of multiple myeloma are discussed.

Thalidomide maintenance following high-dose melphalan with autologous stem cell support in myeloma

BACKGROUND

Recent experience with thalidomide maintenance after high-dose chemotherapy with autologous stem cell support has demonstrated improvement in progression-free survival (PFS) and overall survival (OS). We further explored the tolerability and efficacy of lower doses of maintenance thalidomide in this single-institution study.

PATIENTS AND METHODS

Thirty-eight patients with myeloma were enrolled and treated with melphalan 200 mg/m(2) followed by autologous stem cell transplantation. Thalidomide 50 mg per day was started on day > or = 60 after recovery of blood counts and was escalated to a maximum dose of 200 mg per day. Responses were assessed at 2 months, 1 year, and 2 years after transplantation.

RESULTS

Of the 38 enrolled patients, 7 patients never received thalidomide. Among 31 patients receiving thalidomide, complete or very good partial responses were observed in 65% and 42% of patients at 1 and 2 years, respectively. Tolerability was a major issue, with only 17 patients completing 1 year of thalidomide. The goal of dosing 200 mg per day was achieved in just 17 of 31 patients, and the median tolerated thalidomide dose was 100 mg per day. Sensory neuropathy was the primary reason for dose modification and discontinuation. No thromboembolic events were observed. The median PFS was 20.8 months, and the median OS was > 60 months.

CONCLUSION

Thalidomide maintenance at a goal dose of 200 mg per day was not feasible in this population, with our data suggesting that 100 mg per day is a more reasonable maintenance dose.

Current Trends in Multiple Myeloma Management

Treatment of multiple myeloma, a B-cell cancer, is usually palliative, however, as a result of intensive clinical research there are numerous new treatment options available today. The present review summarizes non-transplant treatment options for multiple myeloma on the basis of available publications. Treatment with new substances, such as immunomodulatory agents, farnesyl transferase inhibitors and apoptosis stimulators, and their mechanisms of action are discussed. In addition to this systematic review of the available evidence on multiple myeloma therapy we have also summarized current recommendations from national and international organizations on aspects of the treatment of multiple myeloma. This should enable readers to see different points of view at a glance and, hopefully, will provide a basis for translation of the available evidence into the best possible therapy.

Thalidomide in the treatment of multiple myeloma

Thalidomide--either alone or in combination with dexamethasone or chemotherapy--has shown significant activity in relapsed/refractory disease. When used in the induction regimens in untreated patients, it significantly increases the response rates as well progression-free survival. Moreover, thalidomide as a maintenance therapy has become a very attractive option. However, the toxicity profile of the drug, mainly neurotoxicity and thrombotic events, mandate careful monitoring of patients treated with thalidomide, whether as the first line, in the relapsed setting, or as maintenance. In this chapter we will review the pharmacology, mechanisms of action, and toxicity of the drug, and will focus on available data from clinical experience and randomized trials of thalidomide in the different settings of multiple myeloma: refractory/relapsed disease, upfront treatment in patients who are eligible for high-dose therapy as well as those who are not, and finally the use of thalidomide as a maintenance treatment.

Role of stem cell transplantation

Hematopoietic stem cell transplantation (SCT) was introduced in the treatment of multiple myeloma in the 1980s. In the autologous setting, the use of peripheral blood stem cells instead of bone marrow has markedly improved feasibility. In fit patients who have normal renal function and are younger than 65 years of age, randomized studies have shown the superiority of autologous stem cell transplantation (ASCT) compared with conventional chemotherapy. ASCT is now considered the standard of care in this population of patients. It is currently challenged, however, by the introduction of novel agents, such as thalidomide, bortezomib, and lenalidomide. The role of allogenic SCT remains controversial, even with reduced intensity conditionings. Prospective studies still are needed to evaluate the impact of both autologous and allogeneic SCT in this new era.

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.

Complications of myeloma therapy

The advent of new therapies for multiple myeloma brings new hope for patients but also new side effects. Emerging information about the risks of supportive care therapies, including long-term, high-intensity bisphosphonate use and erythropoiesis-stimulating agents, is examined. As the number of drugs in the myeloma armamentarium grows, so does the list of possible side effects and interactions. With current progress, not only are there more complications to consider but patients are also living longer and the risk for delayed complications is becoming more relevant. The author provides perspective about the risks for the most active and commonly used single-agent and combination myeloma therapies.

BiRD (Biaxin [clarithromycin]/Revlimid [lenalidomide]/dexamethasone) combination therapy results in high complete- and overall-response rates in treatment-naive symptomatic multiple myeloma

This trial determined the safety and efficacy of the combination regimen clarithromycin (Biaxin), lenalidomide (Revlimid), and dexamethasone (BiRD) as first-line therapy for multiple myeloma. Patients received BiRD in 28-day cycles. Dexamethasone (40 mg) was given orally once weekly, clarithromycin (500 mg) was given orally twice daily, and lenalidomide (25 mg) was given orally daily on days 1 to 21. Objective response was defined by standard criteria (ie, decrease in serum monoclonal protein [M-protein] by at least 50%, and a decrease in urine M-protein by at least 90%). Of the 72 patients enrolled, 65 had an objective response (90.3%). A combined stringent and conventional complete response rate of 38.9% was achieved, and 73.6% of the patients achieved at least a 90% decrease in M-protein levels. This regimen did not interfere with hematopoietic stem-cell harvest. Fifty-two patients who did not go on to receive transplants received continued therapy (complete response, 37%; very good partial response, 33%). The major adverse events were thromboembolic events, corticosteroid-related morbidity, and cytopenias. BiRD is an effective regimen with manageable side effects in the treatment of symptomatic, newly diagnosed multiple myeloma. This trial was registered at www.clinicaltrials.gov as #NCT00151203.

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.

Incorporating bortezomib into upfront treatment for multiple myeloma: early results of total therapy 3

Total therapy 3 incorporated bortezomib into a melphalan-based tandem transplant regimen for 303 newly diagnosed patients with myeloma. Induction chemotherapy prior to and consolidation chemotherapy after transplants each consisted of two cycles of VTD-PACE (bortezomib, thalidomide, dexamethasone and 4-d continuous infusions of cis-platin, doxorubicin, cyclophosphamide, etoposide); 3-year maintenance comprised monthly cycles of VTD in the first and TD in the remaining years. The median age was 59 years (age >64 years, 28%). A minimum of 20 x 10(6) CD34 cells/kg was collected in 87% of patients; 83% completed both transplants, and only 5% suffered a treatment-related death. At 24 months, 83% had achieved near-complete remission, which was sustained in 88% at 2 years from its onset. With a median follow-up of 20 months, 2-year estimates of event-free and overall survival were 84% and 86% respectively. The 44 patients who experienced an event more often had a high-risk gene array profile, cytogenetic abnormalities and indicators of high lactate dehydrogenase, beta-2-microglobulin, creatinine and International Staging System stage. Toxicities of grade > 2 included thrombo-embolic events in 27% and peripheral neuropathy in 12%. Results of this phase-2 study demonstrated that bortezomib could be safely combined with multi-agent chemotherapy, effecting near-complete remission status and 2-year survival rates in more than 80% of patients.

Management of multiple myeloma: the changing landscape

Many changes have been incorporated into the approach to multiple myeloma over the last few years, due to improvements in our understanding of the disease biology. New diagnostic and prognostic criteria from the International Myeloma Working Group have clarified the initial clinical approach to this disease. The prognostic impact of chromosomal abnormalities is now recognized, and the detection of specific abnormal cytogenetics is beginning to influence therapeutic decisions. The introduction of the novel agents thalidomide, bortezomib and lenalidomide has expanded treatment options at different points in the disease course; these agents are being evaluated in conjunction with conventional chemotherapy and stem cell transplantation. This report highlights some of the key recent findings in multiple myeloma, and describes areas for future research.

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.

Current Standards for First-Line Therapy of Multiple Myeloma

Current standards of care for first-line treatment of multiple myeloma are evolving rapidly because of the introduction of regimens based on novel agents with unique mechanisms of action: the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide. These regimens are becoming increasingly widely used, offering substantially greater benefit to patients in terms of higher response rates and, more importantly, prolonged response durations and survival compared with established standard first-line treatment strategies. A notable aspect of many of these emerging treatment options is the very high rates of complete response (CR) reported, previously only seen with transplantation-based strategies. Achievement of CR is prognostic for improved overall survival; therefore, the higher rates and quality of responses seen with the new regimens might substantially improve patient outcomes versus established standards of care. For example, addition of each of the 3 novel agents to melphalan/prednisone results in higher overall response rates and CR rates, as well as prolonged progression-free and overall survival, compared with melphalan/prednisone alone. Similar substantial improvements in response are seen with addition of the 3 agents to single-agent dexamethasone and the use of bortezomib or thalidomide in VAD (vincristine/doxorubicin/dexamethasone)-like regimens, as induction therapies before stem cell transplantation and in patients not proceeding to transplantation. Ultimately, these novel regimens might obviate the need for stem cell transplantation in a sizeable proportion of patients. The emergence of these new therapeutic options appears likely to significantly alter the first-line treatment paradigm for patients with multiple myeloma.

Targeted therapeutics for multiple myeloma: The arrival of a risk-stratified approach

Multiple myeloma (MM) remains an incurable hematologic malignancy characterized by frequent early responses, inevitably followed by treatment relapse. Until recently, few effective therapies existed. Indeed, the use of alkylating agents and corticosteroids had remained the treatment of choice for almost four decades. Several novel agents for MM have now become available, including the immunomodulatory drugs thalidomide and lenalidomide, as well as the proteasome inhibitor bortezomib. Each of these agents is undergoing extensive clinical evaluation in combination with other therapies to produce unprecedented response rates in newly diagnosed and relapsed MM. Nevertheless, relapse remains universal and further therapeutics with broad activity are required. Importantly, it has become clear that pivotal genetic events are the primary harbingers of clinical outcome and novel targeted therapy approaches using existing approved drugs or novel agents, which address that disrupted signaling pathways are now in various stages of clinical testing. It seems increasingly likely that novel drug combinations, which together turn off these critical Achilles heels, will become the standard of care and that treatment will become increasingly personalized and guided by genetic testing and prognostic factors.

Treatment of newly diagnosed multiple myeloma based on Mayo Stratification of Myeloma and Risk-adapted Therapy (mSMART): consensus statement

Multiple myeloma is a neoplastic plasma cell dyscrasia that on a yearly basis affects nearly 17,000 individuals and kills more than 11,000. Although no cure exists, many effective treatments are available that prolong survival and improve the quality of life of patients with this disease. The purpose of this consensus is to offer a simplified, evidence-based algorithm of decision making for patients with newly diagnosed myeloma. In cases in which evidence is lacking, our team of 18 Mayo Clinic myeloma experts reached a consensus on what therapy could generally be recommended. The focal point of our strategy revolves around risk stratification. Although a multitude of risk factors have been identified throughout the years, including age, tumor burden, renal function, lactate dehydrogenase, beta2-microglobulin, and serum albumin, our group has now recognized and endorsed a genetic stratification and patient functional status for treatment.

High dose melphalan or intermediate dose melphalan can be well tolerated and result in good response rates in selected elderly patients with myeloma

We have used two strategies for treating myeloma patients aged 65-75 years. Those fit enough underwent Cyclophosphamide mobilisation and PBSCT using melphalan 200mg/m(2) (HDM) (n=15, median 67 years). Those less fit were mobilised with G-CSF and received melphalan 70mg/m(2) (IDM) (n=15, median 69 years). Where possible sufficient PBSC were collected so that patients not in CR after their first IDM, underwent a second IDM procedure (n=6). The treatment was well tolerated with zero day+100 TRM. Median cell dose was 4.85x10(6)CD34+cells/kg and 2.7x10(6) in the HDM and IDM groups, respectively. Neutrophil engraftment was faster in the HDM group but despite this there was a trend to earlier discharge in the IDM group (13 days versus 15 days) and lower antibiotic and anti-fungal usage, suggesting better tolerability. Response rates were similar with CRs achieved in 7/15 patients receiving HDM and 9/15 receiving IDM (6 after the first and 3 after the second procedure). Three patients did not undergo a second IDM due to insufficient cells. In the IDM group 11/15 remain alive at a median follow up of 14 months with 5 in CR, whilst in the HDM group 12/15 are alive with 5 in CR at a median follow up of 15.5m. We conclude both approaches have comparable efficacy but that IDM may be better tolerated in an older age group.

Autologous stem cell transplantation is safe and feasible in elderly patients with multiple myeloma

Several clinical trials have shown the superiority of autologous stem cell transplantation over conventional dose therapy for patients with multiple myeloma. This treatment, however, is limited to younger patients (<65 years) owing to concerns about toxicity and treatment-related mortality (TRM) in older patients. We treated 26 elderly myeloma patients (>70 years), who received a preparative regimen of melphalan 200 mg/m2 (19 patients), melphalan 180 mg/m2 (six patients) or melphalan 140 mg/m2 (one patient). Twenty-two of the 26 patients were alive after a median follow-up of 25 months (range=8-74). Responses (complete+partial response) were seen in 20 patients (77%), five (19%) of which were complete responses. Median PFS was 24 months, whereas median OS has not been reached. Cumulative incidence of 100-day TRM was 0%. Three-year PFS and OS were 39% (range=16-61) and 65% (range=35-83), respectively. A low serum albumin (<3.5 g/dl) was associated with a shorter PFS (P=0.02). Patients with relapsed disease at transplant, and an interval of >12 months between diagnosis and autotransplant, had a shorter OS (P=0.0004 and 0.04). HDT and autologous transplant is safe and feasible in elderly myeloma patients.

The role of thalidomide in multiple myeloma

Thalidomide has been demonstrated to be active as a first-line and salvage therapy in patients with multiple myeloma. Numerous studies over the past 8 years have shown it to induce high response rates and improve event-free survival in newly diagnosed patients as well as those with relapsed/refractory disease. Recent randomized clinical trials have demonstrated that thalidomide-based regimens are superior to conventional treatments in terms of response rates and event-free survival. However, few trials have demonstrated a survival benefit with thalidomide, indicating the need for further trials. This review will focus on recent trials of thalidomide in relapsed/refractory and newly diagnosed multiple myeloma and address some of the common adverse events associated with thalidomide treatment.

Strategies for risk-adapted therapy in myeloma

It is clear that the clinical heterogeneity of multiple myeloma (MM) is dictated, in large part, by disease biology, predominantly genetics.(1) As novel therapeutics have emerged, and augmented our treatment armamentarium against the disease, it is increasingly important to introduce a risk-adapted approach for the optimal management of patients.(2) The selection of ideal candidates for high-dose chemotherapy with stem cell support (HDT) and maintenance will undoubtedly have to include baseline knowledge of the genetic nature of the individual. The limited duration of responses after HDT for patients with t(4;14)(p16;q32), t(14;16)(q32;q23) and 17p13 deletions highlight the need to develop a risk-adapted treatment strategy.(3)(-)(5) Novel ways of determining outcome such as the use of gene expression profiling have demonstrated differentiating capabilities not previously observed.(6) Likewise, the order of introduction of novel therapeutic agents (during induction and in the relapsing patient) will be potentially directed by similar information. As we have previously stated, MM is not only multiple but also "many."(7) Accordingly, treatment strategies will be tailored based on risk determination, genetic composition and host features.

Treatment Strategies in Elderly Patients with Multiple Myeloma

Multiple myeloma (MM), a plasma cell malignancy, is a disorder of the elderly with an increasing prevalence as the average life expectancy increases. Survival remains unacceptably low in elderly patients with MM, in whom the gold standard of treatment has been, until recently, oral melphalan and prednisolone, which induces a response rate of approximately 50% and overall survival of <3 years. In the last 15 years, traditional treatment paradigms for elderly patients with MM have been challenged not only as a result of the change in what we define as 'elderly' but also as a result of the reduced morbidity and treatment-related mortality associated with high-dose chemoradiotherapy (HDT) and autologous stem cell transplantation (ASCT), and the emergence of novel therapies including thalidomide, its immunomodulator drug derivative lenalidomide and the first-in-class proteasome inhibitor, bortezomib. In this review, we examine currently available data regarding the treatment of MM in the elderly population. Recent years have seen a paradigm shift in the standard of care of elderly patients with MM from oral melphalan and prednisolone to approaches including HDT with ASCT using intermediate-dose melphalan in selected elderly patients, and the evaluation of and incorporation of drugs such as thalidomide, bortezomib and lenalidomide. Importantly, we now have been able to change the traditional goal of palliation in the elderly group of patients to a more ambitious objective of achieving a complete response or a near complete response, in the hope that this will translate into improved progression-free survival, overall survival and quality of life.

Systemic Immunoglobulin Light-Chain Amyloidosis

Amyloidosis is a rare disease in which amyloid fibrils compromise organ function and lead to death. Systemic immunoglobulin light-chain amyloidosis, usually caused by free light chains (FLCs) made by clonal plasma cells, is the most frequent type. Hereditary and senile systemic amyloidosis are less frequent types. Rarely, a patient with a tissue diagnosis of amyloidosis might have a monoclonal gammopathy and a hereditary protein. In systemic immunoglobulin light-chain amyloidosis, circulating clonal light chains can be measured with the FLC assay and provide a target for therapy aimed at eliminating the underlying plasma cell disorder while supporting the patient. Elimination of the pathologic FLC can lead to resorption of amyloid deposits and improvement in organ function. Monthly oral melphalan and dexamethasone for 1 year is effective therapy for patients not eligible for autologous stem cell transplantation (SCT) but carries a risk of myelodysplasia. For patients with limited organ involvement, SCT is an effective approach and, when followed after SCT by adjuvant thalidomide and dexamethasone for persistent plasma cell disease, achieves a high 1-year hematologic response rate. Complete hematologic responses can be durable beyond a decade and are usually associated with organ recovery. New agents, such as bortezomib and lenalidomide, have shown promising activity, and novel monoclonal antibody approaches are also under active investigation.

Highlights from the 42nd annual meeting of the American Society of Clinical Oncology

The results of approximately 3700 preclinical and clinical studies were presented at the 42nd annual meeting of the American Society of Clinical Oncology (ASCO) held 2-6 June 2006, in Atlanta, Georgia. The annual ASCO meeting is the largest forum in which oncology professionals from around the world report the latest advances in cancer research, encompassing a wide spectrum of subjects on molecular biology, prevention, diagnosis and therapy of tumours. The present report summarises some of the more important results of the studies presented at the meeting. In particular, the authors focused on findings from randomised Phase III trials that, in their opinion, are most likely to have an immediate effect on clinical practice. The top advances were grouped into four major themes (breast cancer, colorectal cancer, non-small cell lung cancer and selected presentations from the plenary session). In addition, selected Phase I and II studies on promising novel therapeutic agents were briefly described. Finally, a 'question and answer' format was adopted to report results of interesting studies on some hot topics.

Thalidomide in multiple myeloma: past, present and future

Thalidomide was introduced in the treatment of multiple myeloma in the late 1990s. Following the initial results, which demonstrated dramatic response rates in heavily pretreated patients, a number of Phase II studies have confirmed the efficacy of this agent in relapsed patients. However, a high incidence of side effects at the dosage initially recommended (400 mg/day) justified further studies with lower doses of thalidomide given alone or in combination with dexamethasone or chemotherapy. Thalidomide is currently considered as one of the most active agents in relapsed myeloma. Recent studies have demonstrated that thalidomide could also be used as part of frontline therapy. The combination of thalidomide plus dexamethasone as initial therapy appears to be slightly superior to dexamethasone alone or to vincristine–doxorubicine–dexamethasone, but with an increased risk of deep vein thrombosis. Maintenance with thalidomide after autologous transplantation appears to increase the complete remission rate and to prolong progression-free survival. The combination of thalidomide plus melphalan and prednisone is superior to the classical melphalan–prednisone regimen in elderly patients, and will become the standard of care. Thalidomide has been registered in the USA in combination with dexamethasone in newly diagnosed patients, but is not yet registered in the European Union. Its use is currently challenged by bortezomib and by thalidomide’s analog lenalidomide.