A practical guide to defining high-risk myeloma for clinical trials, patient counseling and choice of therapy

Importance of achieving a complete response in multiple myeloma, and the impact of novel agents

The goal of treatment for multiple myeloma (MM) is to improve patients' long-term outcomes. One important factor that has been associated with prolonged progression-free and overall survival is the quality of response to treatment, particularly achievement of a complete response (CR). There is extensive evidence from clinical studies in the transplant setting in first-line MM demonstrating that CR or maximal response post-transplant is significantly associated with prolonged progression-free and overall survival, with some studies demonstrating a similar association with postinduction response. Supportive evidence is also available from studies in the nontransplant and relapsed settings. With the introduction of bortezomib, thalidomide, and lenalidomide, higher rates of CR are being achieved in both first-line and relapsed MM compared with previous chemotherapeutic approaches, thereby potentially improving long-term outcomes. While standard CR by established response criteria has been shown to have differential prognostic impact compared with lesser responses, increasingly sensitive analytic techniques are now being explored to define more stringent degrees of CR or elimination of minimal residual disease (MRD), including multiparameter flow cytometry and polymerase chain reaction. Demonstrating eradication of MRD by these techniques has already been shown to predict for improved outcomes. Here, we review the prognostic significance of achieving CR in MM and highlight the importance of CR as an increasingly realizable goal at all stages of treatment. We discuss clinical management issues and provide recommendations relevant to practicing oncologists, such as the routine use of sensitive techniques for assessment of disease status to inform evidence-based decisions on optimal patient management.

Treatment of multiple myeloma: a comprehensive review

Multiple myeloma (MM) is a neoplastic plasma cell disorder that results in end-organ damage (hypercalcemia, renal insufficiency, anemia, or skeletal lesions). Patients should not be treated unless they have symptomatic (end-organ damage) MM. They should be classified as having high-risk or standard-risk disease. Patients are classified as high risk in the presence of hypodiploidy or deletion of chromosome 13 (del[13]) with conventional cytogenetics, the presence of t(4:14), t(14;16), t(14;20) translocations or del(17p) with fluorescence in situ hybridization. High-risk disease accounts for about 25% of patients with symptomatic MM. If the patient is deemed eligible for an autologous stem cell transplantation (ASCT), 3 or 4 cycles of lenalidomide and low-dose dexamethasone, or bortezomib and dexamethasone, or thalidomide and dexamethasone are reasonable choices. Stem cells should then be collected and one may proceed with an ASCT. If the patient has a complete response or a very good partial response (VGPR), the patient may be followed without maintenance therapy. If the patient has a less than VGPR, a second ASCT is encouraged. If the patient is in the high-risk group, a bortezomib-containing regimen to maximum response followed by 2 additional cycles of therapy is a reasonable approach. Lenalidomide and low-dose dexamethasone is another option for maintenance until progression. If the patient is considered ineligible for an ASCT, then melphalan, prednisone, and thalidomide is suggested for the standard-risk patient, and melphalan, prednisone, and bortezomib (MPV) for the high-risk patient. Treatment of relapsed or refractory MM is covered. The novel therapies-thalidomide, bortezomib, and lenalidomide-have resulted in improved survival rates. The complications of MM are also described. Multiple myeloma is a plasma cell neoplasm that is characterized by a single clone of plasma cells producing a monoclonal protein (M-protein). The malignant proliferation of plasma cells produces skeletal destruction that leads to bone pain and pathologic fractures. The M-protein might lead to renal failure, hyperviscosity syndrome, or through the suppression of uninvolved immunoglobulins, recurrent infections. Anemia and hypercalcemia are common complications.

Current multiple myeloma treatment strategies with novel agents: a European perspective

The treatment of multiple myeloma (MM) has undergone significant developments in recent years. The availability of the novel agents thalidomide, bortezomib, and lenalidomide has expanded treatment options and has improved the outcome of patients with MM. Following the introduction of these agents in the relapsed/refractory setting, they are also undergoing investigation in the initial treatment of MM. A number of phase III trials have demonstrated the efficacy of novel agent combinations in the transplant and nontransplant settings, and based on these results standard induction regimens are being challenged and replaced. In the transplant setting, a number of newer induction regimens are now available that have been shown to be superior to the vincristine, doxorubicin, and dexamethasone regimen. Similarly, in the front-line treatment of patients not eligible for transplantation, regimens incorporating novel agents have been found to be superior to the traditional melphalan plus prednisone regimen. Importantly, some of the novel agents appear to be active in patients with high-risk disease, such as adverse cytogenetic features, and certain comorbidities, such as renal impairment. This review presents an overview of the most recent data with these novel agents and summarizes European treatment practices incorporating the novel agents.

Small cell tumors of bone

Bone tumors are fortunately rare, but small cell tumors of bone are a relatively common subset of these lesions. They comprise of a diverse group of primary and metastatic neoplasms in both children and adults. The most common small cell tumors of bone include Ewing sarcoma/primitive neuroectodermal tumor, small cell osteosarcoma, multiple myeloma, lymphoma, leukemia, neuroblastoma, rhabdomyosarcoma, and Langerhans cell histiocytosis. Although each entity has its distinctive features, the differential diagnosis of this group of tumors is still challenging because they are all "small, blue, and round cell tumors", histologically. The correct diagnosis of small cell tumors of bone depends on an evaluation of clinical, radiologic, pathologic, and genetic features. Patients' age and sex are very important, as are the signs and symptoms at presentation. Radiologically, which bone is involved, the specific portion of the bone (epiphysis, metaphysis, or diaphysis; cortex vs. medulla) involved, and the radiographic manifestations (lytic, blastic, or mixed lytic and blastic) are also often critical parameters for the diagnosis. In recent years, with a better understanding of the molecular and cytogenetic background of several small cell tumors, more accurate diagnoses have been supported by the clinicopathologic criteria and by a panel of immunohistochemical studies. In this review we will provide an overview of the clinical, radiologic, pathologic, and genetic characteristics of these tumors.

Treatment of newly diagnosed multiple myeloma: advances in current therapy

The past decade has seen incredible progress in the treatment of myeloma as a result of more widespread application of autologous stem cell transplantation and introduction of several new drugs. Hence, the survival of patients with this disease has significantly improved during this period. The treatment approach for patients with myeloma has undergone a paradigm shift as a result of the different choices available for treating the patients with newly diagnosed myeloma. In addition, appreciation of the heterogeneity in the outcome of these patients and the impact of genetics on the prognosis has led to efforts at developing a risk-adapted approach to treatment. This article summarizes the recent advances in the treatment of newly diagnosed myeloma and suggests a treatment algorithm for approaching newly diagnosed myeloma.

How I treat multiple myeloma in younger patients

Therapeutic options for multiple myeloma (MM) patients have changed quickly in recent years and uncertainty has arisen about optimal approaches to therapy. A reasonable goal of MM treatment in younger “transplant eligible” patients is to initiate therapy with a target goal of durable complete remission, and the anticipated consequence of long-term disease control. To achieve this goal we recommend induction therapy with multi-agent combination chemotherapies (usually selected from bortezomib, lenalidomide, thalidomide, cyclophosphamide, and corticosteriods) which when employed together elicit frequent, rapid, and deep responses. We recommend consolidation with high-dose melphalan and autologous stem cell transplantation in the majority of patients willing and able to undergo this procedure and subsequent maintenance therapy, especially in those failing to achieve a complete response or at high risk for early relapse based on prognostic, genetically defined risk factors. Defining genetic risk for early relapse is therefore an important aspect of early diagnostic testing and attention to minimizing expected toxicities once therapy begins is critical in ensuring the efficacy of modern combination therapy approaches. When access to newer drugs is restricted participation in clinical trials should be pursued.

Management of newly diagnosed symptomatic multiple myeloma: updated Mayo Stratification of Myeloma and Risk-Adapted Therapy (mSMART) consensus guidelines

Multiple myeloma is a malignant plasma cell neoplasm that affects more than 20,000 people each year and is the second most common hematologic malignancy. It is part of a spectrum of monoclonal plasma cell disorders, many of which do not require active therapy. During the past decade, considerable progress has been made in our understanding of the disease process and factors that influence outcome, along with development of new drugs that are highly effective in controlling the disease and prolonging survival without compromising quality of life. Identification of well-defined and reproducible prognostic factors and introduction of new therapies with unique modes of action and impact on disease outcome have for the first time opened up the opportunity to develop risk-adapted strategies for managing this disease. Although these risk-adapted strategies have not been prospectively validated, enough evidence can be gathered from existing randomized trials, subgroup analyses, and retrospective studies to develop a working framework. This set of recommendations represents such an effort-the development of a set of consensus guidelines by a group of experts to manage patients with newly diagnosed disease based on an interpretation of the best available evidence.

Novel therapies in multiple myeloma for newly diagnosed nontransplant candidates

In the twenty-first century, melphalan-prednisone can no longer be regarded as the standard treatment of multiple myeloma patients not eligible for high-dose melphalan followed by autologous stem cell transplantation. The introduction of thalidomide, lenalidomide, and bortezomib has improved the arsenal of therapeutic options in multiple myeloma. Indeed, randomized studies have shown that melphalan-prednisone-thalidomide and melphalan-prednisone-bortezomib are superior to melphalan-prednisone alone. In addition, other combinations, including lenalidomide, are under study. In this review, we discuss the role of novel therapies in multiple myeloma in elderly multiple myeloma patients. Important aspects, such as toxicity and the role of prognostic factors, are also addressed.

Plasma cell myeloma

Plasma cell myeloma is a heterogenous disease with variable clinical presentation and outcome. The prognosis is largely determined by tumor biology. Newer therapeutic agents are rapidly changing the survival outlook of myeloma patients.

Combinations of cytogenetics and international scoring system can predict poor prognosis in multiple myeloma after high-dose chemotherapy and autologous stem cell transplantation

High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is a standard therapy for newly diagnosed multiple myeloma. Combinations of recently proposed prognostic factors such as cytogenetics and international scoring system (ISS) may be useful to predict prognosis after ASCT. This study evaluated 60 consecutive patients who underwent ASCT in four institutes. The median age of patients was 57 years old. Cytogenetic analyses of bone marrow at diagnosis detected metaphase abnormalities in 9 of 51 patients and interphase abnormalities in six of 35 patients (17p13 deletion, t(4;14) and t(14;16)). Seventeen patients had ISS stage 3 at diagnosis. Twenty-five patients who had any of these risk factors were defined as high risk. All patients were conditioned with high-dose melphalan. With a median follow-up of 3.4 years, overall survival and event-free survival at 3 years were significantly worse in high-risk patients (48% vs. 97%; P = 0.0005 and 16% vs. 37%; P = 0.038, respectively) despite the higher CR plus VGPR rate among high-risk patients. In addition, survival at 1 year after progression was significantly worse in high-risk patients despite salvage chemotherapy containing thalidomide (32% vs. 100%, P = 0.0001). Combinations of cytogenetics and ISS could readily predict prognosis. Quality of response is a poor surrogate marker for ultimate outcome. High-risk patients may need more effective treatment.

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

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

Gene hypermethylation in multiple myeloma: lessons from a cancer pathway approach

Multiple myeloma (MM) is an incurable plasma cell neoplasm. Pathogenesis involves upregulation of D-type cyclins and activation of oncogenes, but little is known about the role of tumor suppressor genes. Gene hypermethylation is an alternative mechanism of tumor suppressor gene inactivation. Various approaches have been used to elucidate the role of gene hypermethylation in MM, including a candidate gene approach, microarray approach for genes upregulated by hypomethylating agents, and a cancer pathway approach, which enables a comprehensive picture of the involvement of multiple tumor suppressor genes in MM. Based on the cancer pathway approach, the following data on the involvement of cell cycle control, intrinsic tumor suppressor, and cell signaling were derived. First, among the INK4 and CIP/KIP families of cyclin-dependent kinase inhibitors, only CDKN2B and CDKN2A are frequently hypermethylated. Second, methylation of SHP1 and soluble Wnt inhibitors is associated with constitutive activation of JAK/STAT and Wnt signaling. Importantly, downregulation of the signaling pathways can be restored by demethylation and re-expression of SHP1 and soluble Wnt inhibitors, which is potentially important therapeutically. Third, of the tumor suppressor genes involved in the DAPK/P14/HDM2/P53/Apaf-1 pathway, only DAPK is frequently methylated, which appeared to be an adverse prognostic factor to survival. Lastly, apart from being implicated in the progression from monoclonal gammopathy of unknown significance to MM, aberrant gene promoter methylation might also account for late disease progression in MM. Future studies are needed to delineate the biologic consequence of gene hypermethylation, the prognostic effect of gene methylation, and the possibility of hypomethylation therapy.

Novel therapies for relapsed myeloma

Treatment of myeloma relapse needs to be individualized to reflect the effectiveness and toxicities of prior therapies, with consideration given to pragmatic issues such as the tempo of relapse, age of the patient, access to drugs and patient preference. In general, combination therapies have been associated with higher response rates and improved progression-free survival and may be preferable when a rapid response is required. Nevertheless, in a slower-tempo relapse it is unclear at this juncture whether sequencing of drugs or multi-agent combinations offer superior overall survival results. Fortunately, active novel agents that offer further possibilities for some myeloma patients have become available in clinical trials. In this review we will describe the various classes of novel drugs being tested and the pros and cons of preclinical testing, and will particularly focus on two agents with single-agent activity in myeloma: carfilzomib, a proteasome inhibitor, and pomalidomide, a member of the immunomodulatory class of drugs.

Treatment of newly diagnosed myeloma

The introduction of thalidomide, bortezomib and lenalidomide has dramatically changed the treatment paradigm of multiple myeloma (MM). In patients eligible for autologous stem cell transplant (ASCT), combinations including thalidomide/dexamethasone (Thal/Dex) or bortezomib/dexamethasone (Bort/Dex) or lenalidomide/dexamethasone (Rev/Dex) have been introduced as induction regimens in patients eligible for ASCT. New induction regimens have significantly increased complete response rate before and after ASCT with a positive impact on progression-free survival. Maintenance therapy with thalidomide, under investigation with lenalidomide, may further prolong remission duration. In patients not eligible for ASCT, randomized studies have shown that melphalan, prednisone, thalidomide (MPT) and melphalan, prednisone and bortezomib (MPV) are both superior to melphalan and prednisone (MP), and are now considered standard of care. Ongoing trials will soon assess if MP plus lenalidomide may be considered an attractive option. More complex regimens combining thalidomide or bortezomib or lenalidomide with cyclophosphamide or doxorubicin have been also tested. In small cohorts of patients bortezomib or lenalidomide may overcome the poor prognosis induced by deletion 13 or translocation t(4;14) or deletion 17p13. If these data will be confirmed, a cytogenetically risk-adapted strategy might become the most appropriate strategy.

Prognostic value of the serum free light chain ratio in newly diagnosed myeloma: proposed incorporation into the international staging system

To determine if the serum free light chain (FLC) ratio has prognostic value in patients with symptomatic multiple myeloma (MM), baseline serum samples from a well-characterized cohort of 790 newly diagnosed MM patients were tested with the FLC assay. FLC ratio was calculated as kappa/lambda (reference range 0.26-1.65). On the basis of the distribution of values, a cutpoint kappa/lambda FLC ratio of <0.03 or >32 was chosen for further analysis. Overall survival was significantly inferior in patients with an abnormal FLC ratio of <0.03 or >32 (n=479) compared with those with an FLC ratio between 0.03 and 32 (n=311), with median survival of 30 versus 39 months, respectively. We incorporated abnormal FLC ratio with the International Staging System (ISS) risk factors (that is, albumin <3.5 g/dl and serum beta(2)-microglobulin >or=3.5 g/l), to create a risk stratification model with improved prognostic capabilities. Patients with 0, 1, 2 or 3 adverse risk factors had significantly different overall survival, with median survival times of 51, 39, 30 and 22 months, respectively (P<0.001). These findings suggest that the serum FLC ratio at initial diagnosis is an important predictor of prognosis in myeloma, and can be incorporated into the ISS for improved risk stratification.

Bortezomib in the front-line treatment of multiple myeloma

Front-line therapy for multiple myeloma is rapidly evolving with the development of new, highly active regimens based on novel agents such as bortezomib. Bortezomib-based regimens are demonstrating substantial efficacy both as induction prior to stem cell transplantation and as treatment for patients ineligible for transplant, offering rapid and durable responses with consistently high rates of complete response, a surrogate end point for improved overall survival. Combinations of bortezomib plus established and novel agents, such as melphalan-prednisone, dexamethasone, doxorubicin, thalidomide-dexamethasone and, most recently, lenalidomide-dexamethasone, are proving superior to or more promising than previous standards of care. Importantly, these regimens are demonstrating enhanced activity across the front-line population, including patients with renal impairment, high-risk cytogenetics and advanced bone disease. Impressive Phase 3 results with bortezomib-melphalan-prednisone, bortezomib-dexamethasone and bortezomib-thalidomide-dexamethasone should facilitate the establishment of these highly effective regimens as key therapies for newly diagnosed myeloma.

Evaluation of the cytogenetic aberration pattern in amyloid light chain amyloidosis as compared with monoclonal gammopathy of undetermined significance reveals common pathways of karyotypic instability

Chromosomal aberrations (CAs) have emerged as important pathogenetic and prognostic factors in plasma cell disorders. Using interphase fluorescence in situ hybridization (FISH) analysis, we evaluated CAs in a series of 75 patients with amyloid light chain amyloidosis (AL) as compared with 127 patients with monoclonal gammopathy of unknown significance (MGUS). We investigated IgH translocations t(11;14), t(4;14), and t(14;16) as well as gains of 1q21, 11q23, and 19q13 and deletions of 8p21, 13q14, and 17p13, detecting at least one CA in 89% of the patients. Translocation t(11;14) was the most frequent aberration in AL, with 47% versus 26% in MGUS (P = .03), and was strongly associated with the lack of an intact immunoglobulin (P < .001), thus contributing to the frequent light chain subtype in AL. Other frequent aberrations in AL included deletion of 13q14 and gain of 1q21, which were shared by MGUS at comparable frequencies. The progression to multiple myeloma (MM) stage I was paralleled by an increased frequency of gain of 1q21 (P = .001) in both groups. Similar branching patterns were observed in an oncogenetic tree model, indicating a common mechanism of underlying karyotypic instability in these plasma cell disorders.

Individualizing treatment of patients with myeloma in the era of novel agents

Progress in the understanding of multiple myeloma (MM) cell biology has led to the identification of new relevant prognostic factors and subsequently different risk groups. This concept, together with the recent discovery of new drugs with novel mechanisms of action, will probably lead to individualized treatment according to the different patients' characteristics. In this review, we focus on current available agents already approved for MM, and discuss individualized treatment approaches for both transplantation candidates (subdivided into standard and high-risk patients) and elderly patients. Future progress in MM will be based on using science to inform the design of the optimal combined treatments, and high throughput assays that can assess the ability of combination therapies to induce death of MM cells, both alone and in the bone marrow microenvironment.

Multiple myeloma

Multiple myeloma is a clonal plasma cell malignancy that accounts for slightly more than 10% of all hematologic cancers. In this paper, we present a historically focused review of the disease, from the description of the first case in 1844 to the present. The evolution of drug therapy and stem-cell transplantation for the treatment of myeloma, as well as the development of new agents, is discussed. We also provide an update on current concepts of diagnosis and therapy, with an emphasis on how treatments have emerged from a historical perspective after certain important discoveries and the results of experimental studies.

Outcome after autologous stem cell transplantation for multiple myeloma in patients with preceding plasma cell disorders

A third of patients with multiple myeloma (MM) have a preceding diagnosis of plasma cell proliferative disorder (PCPD), mostly monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM) or plasmacytoma. While autologous stem cell transplantation (SCT) improves survival in MM, it is not clear if patients with preceding PCPD have a different outcome. We identified 151 patients with preceding PCPD from among 804 patients undergoing SCT, and their outcomes were compared. The response rates, including complete responses, were similar between the groups. Patients with a preceding diagnosis of MGUS had longer time to progression (TTP; 27.5 months vs. 17.2 months, P = 0.01), and longer overall survival (OS) from transplant (80.2 months vs. 48.3 months, P = 0.03) compared to those with de novo myeloma. However no differences were seen among those with a preceding diagnosis of SMM or plasmacytoma in terms of TTP or OS from transplant when compared to those with de novo myeloma. Multivariate analysis indicated that the presence of MGUS prior to myeloma was prognostic for post-transplant relapse independent of other known risk factors. Patients with pre-existing MGUS prior to myeloma diagnosis have a better outcome following HDT, reflecting more indolent disease and a favourable biology than those presenting with de novo myeloma.

Perspectives in treatment of AL amyloidosis

Light chain (AL) amyloidosis is the most frequently diagnosed form of systemic amyloid in the western world. The historically poor prognosis of AL amyloidosis appears to be improving with currently reported median survival of c. 40 months compared to 13 months in the early 1990s when low-dose oral melphalan was the mainstay of treatment. Autologous stem cell transplantation (ASCT) achieves the highest rates of complete clonal response but is confounded by substantial treatment-related mortality in AL amyloidosis unless it is restricted to highly selected patients. Newer chemotherapy regimens appear to have a balance of better safety and respectable efficacy with overall outcomes nearly similar to ASCT, but which may be used more widely. There are few data comparing durability, depth of clonal response, rate of organ response and overall survival following ASCT or chemotherapy, but a recent small, randomized trial did not suggest superiority of ASCT to oral melphalan and dexamethasone. There is a compelling need for further and larger randomized trials in this context. At the same time, various new specific anti-amyloid drugs have shown (in early phase studies or animal models) some very promising results. This review attempts to highlight the challenges, controversies and progress in AL amyloidosis.

Genetic events in the pathogenesis of multiple myeloma

The genetics of myeloma has been increasingly elucidated in recent years. Recurrent genetic events, and also biologically distinct and clinically relevant genetic subtypes of myeloma have been defined. This has facilitated our understanding of the molecular pathogenesis of the disease. In addition, some genetic abnormalities have proved to be highly reproducible prognostic factors. With the expanding therapeutic armamentarium, it is time to include genetic assessment as part of clinical evaluation of myeloma patients to guide management. In this review we examine the role of various genetic abnormalities in the molecular pathogenesis of myeloma, and the use of such abnormalities in disease classification, prognosis and clinical management.

Understanding multiple myeloma pathogenesis in the bone marrow to identify new therapeutic targets

Multiple myeloma is a plasma cell malignancy characterized by complex heterogeneous cytogenetic abnormalities. The bone marrow microenvironment promotes multiple myeloma cell growth and resistance to conventional therapies. Although multiple myeloma remains incurable, novel targeted agents, used alone or in combination, have shown great promise to overcome conventional drug resistance and improve patient outcome. Recent oncogenomic studies have further advanced our understanding of the molecular pathogenesis of multiple myeloma, providing the framework for new prognostic classification and identifying new therapeutic targets.

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.