Proteasome inhibitor bortezomib for the treatment of multiple myeloma

Bortezomib (formerly PS-341) has been the first proteasome inhibitor to enter clinical trials in cancer patients. Based on results of preclinical studies showing that this novel agent directly inhibits the proliferation of myeloma cells, induces their apoptosis and abrogates paracrine tumor growth through alteration of myeloma-stromal cell interactions and nuclear factor-kappaB-dependent cytokine secretion, several large phase II and III studies of bortezomib were initiated in patients with advanced relapsed and/or refractory multiple myeloma (MM). Favorable results of these studies led to accelerated approval for use of bortezomib in MM patients who have progressed after at least their second therapy and, more recently, to expanded approval for second-line use in patients on whom one prior therapy has failed. In the meantime, combination studies of bortezomib with various agents, including dexamethasone, DNA-damaging drugs, thalidomide and lenalidomide, have been designed and are currently ongoing in patients with both relapsed/refractory and newly diagnosed disease. Bortezomib offers great promise to overcome resistance to conventional chemotherapy and may be the 'backbone' for the development of more effective treatment strategies to improve patient outcome in MM.

Bortezomib for multiple myeloma

The ubquitin-proteasome pathway is a key regulator of homeostasis within cells, degrading misfolded or redundant proteins, and also those involved in mediating transcription, cell-cycle progression and apoptosis. Inhibition of the 26S proteasome results in accumulation of such proteins and ultimately leads to cell death. Malignant cells are more susceptible to proteasome inhibition due to their higher proliferation rates, protein production and their dependence on anti-apoptotic molecules for cell survival. Bortezomib has recently gained European Commission approval for the treatment of relapsed multiple myeloma on the basis of clinical trials demonstrating its efficacy, tolerability and superiority to high-dose dexamethasone. Preclinical data demonstrates the ability to synergise with other chemotherapeutic agents and overcome drug resistance, and hence combination studies are underway. This review describes the pharmacology, toxicity, preclinical and clinical activity of bortezomib, predominantly in the setting of multiple myeloma.

Serum pleiotrophin levels are elevated in multiple myeloma patients and correlate with disease status

Pleiotrophin (PTN), a tightly regulated angiogenic and mitogenic heparin-binding protein, is markedly elevated in a variety of aggressive solid tumours. The role of PTN in haematological malignancies, however, has not been previously evaluated. This study demonstrated that PTN serum levels were elevated in multiple myeloma (MM) patients when compared with healthy subjects (P < 0.0001). Serum levels of this protein significantly increased during progression of disease, and decreased during response to anti-MM therapy (P < 0.001). These results suggest that serum PTN may be a new biomarker for monitoring the disease status and therapeutic response of MM patients.

Impact of age on survival after intensive therapy for multiple myeloma: a population-based study by the Nordic Myeloma Study Group

The value of intensive therapy, including autologous stem cell transplantation, in newly diagnosed myeloma patients >60 years is not clear. We evaluated the impact of age (<60 years vs. 60-64 years) on survival in a prospective, population-based setting and compared survival with conventionally treated historic controls. The prospective population comprised 452 patients registered between 1998 and 2000. Of these, 414 received intensive therapy. The historic population, derived from our most recent population-based study on conventional therapy, comprised 281 patients. Of these, 243 fulfilled our eligibility criteria for intensive therapy. For patients undergoing intensive therapy it was found that two factors, beta-2-microglobulin and age <60 years vs. 60-64 years, had independent prognostic impact on survival. However, compared with the historic controls a survival advantage was found both for patients <60 (median 66 months vs. 43 months, P < 0.001) and 60-64 years (median 50 months vs. 27 months; P = 0.001). We conclude that in a population-based setting higher age adversely influences outcome after intensive therapy. Our results indicate that intensive therapy prolongs survival also at age 60-64 years but with less superiority than in younger patients.

High-dose melphalan (200 mg/m2) supported by autologous stem cell transplantation is safe and effective in elderly (>or=65 years) myeloma patients: comparison with younger patients treated on the same protocol

Limited information is available on the feasibility and efficacy of autologous stem cell transplantation (ASCT) in multiple myeloma (MM) patients >65 years of age. In 1995-2005, 22 myeloma patients >or=65 years (median 68, eight >or=70) and 79 patients <65 years (median 57) were included in an identical treatment protocol. The first progenitor cell mobilization with cyclophosphamide plus granulocyte-colony stimulating factor (G-CSF) was successful in 95 and 96% of the patients, respectively. To date, 92 patients have received MEL (melphalan) 200 mg/m2 supported by ASCT. No early treatment-related deaths were observed among 22 elderly patients, whereas one younger patient died early. Engraftment and the need for supportive care were comparable between groups. The elderly patients tended to have more WHO grade 3-4 oral or gastrointestinal toxicity when compared to the younger patients (45 vs 23%, P=0.06). After ASCT, a complete response was observed in 44% of the elderly patients and 36% of the younger patients, respectively. No difference was observed between these age groups in progression-free survival (23 vs 21 months) or overall survival (57 vs 66 months) after ASCT. We conclude that MEL200 is a safe and efficacious treatment in selected elderly myeloma patients.

Efficacy of up-front treatment with a double stem cell transplantation in multiple myeloma

BACKGROUND

We report the outcome of 53 patients with multiple myeloma (MM), who received autologous stem cell transplantation (ASCT) from April 1996 to September 2004 at our institution and who survived for more than 3 months after the transplant.

METHODS

Following the first ASCT, 36 patients underwent an up-front second SCT, which consisted of either an ASCT (n = 24) or a reduced-intensity conditioning allogeneic stem cell transplant (RIST) (n = 12). Seventeen patients were given maintenance treatment.

RESULTS

Seventy-seven percent of the patients (n = 41) showed an objective response to the initial therapy prior to the first ASCT. Overall, 60.4% (32 out of 53) and 32.1% (17 out of 53) of the patients had a complete response (CR) and partial response (PR) after the first ASCT, respectively. At the time of analysis, 34 patients (64.2%) were still alive. With a median follow-up of 32 months (range 9-98), the estimated progression-free survival (PFS) and overall survival (OS) at 5 years were 17.0 and 34.9%, respectively. Multivariate analysis revealed that the second SCT, normal hemoglobin and <50% marrow plasma cells were associated with an improved PFS. A second SCT, CR to the first SCT, female gender and an absence of advanced bone lesions were associated with a better OS.

CONCLUSIONS

A second SCT is the most significant factor for an improved PFS and OS after the first ASCT (P < 0.001, respectively). Up-front double SCT is needed to improve the OS and PFS in patients with MM.

A practical update on the use of bortezomib in the management of multiple myeloma

Despite intensive therapy, multiple myeloma (MM) remains an incurable disease, and novel treatment approaches are therefore needed to improve outcome. Bortezomib is the first proteasome inhibitor to be approved by the U.S. Food and Drug Administration (FDA) and the European Agency for the Evaluation of Medicinal Products for the treatment of refractory or relapsed MM following the failure of at least two prior lines of therapy. Recently, it also received approval from the FDA for use as a second-line agent. An expert panel of hematologists met at the Ninth Congress of the European Hematology Association to review clinical data and experience in the treatment of MM with bortezomib, including bortezomib-based combination therapy. The conclusions of this expert panel, together with updated clinical data from the American Society of Hematology 46th Annual Meeting, provide a practical update on the use of bortezomib in MM. Bortezomib has demonstrated significant antitumor activity as a single agent in refractory and/or relapsed MM, with a significantly longer survival than with dexamethasone (1-year overall survival rate of 80% vs. 66%) and a 78% longer median time to progression. In combination therapy, patient responses suggest the possibility of chemosensitization and synergy. Furthermore, bortezomib does not appear to have an adverse effect on subsequent stem cell therapy. Bortezomib is well tolerated; most side effects are only mild to moderate and are manageable. Information is given on the practical management of the most common adverse events, including peripheral neuropathy and thrombocytopenia, and the use of bortezomib in renal and hepatic impairment.

Proteasome inhibitors induce a terminal unfolded protein response in multiple myeloma cells

Multiple myeloma (MM) is an incurable plasma cell malignancy. The 26S proteasome inhibitor, bortezomib, selectively induces apoptosis in MM cells; however, the nature of its selectivity remains unknown. Here we demonstrate that 5 different MM cell lines display similar patterns of sensitivity to 3 proteasome inhibitors (PIs) but respond differently to specific NF-kappaB inhibition. We further show that PIs initiate the unfolded protein response (UPR), a signaling pathway activated by the accumulation of misfolded proteins within the endoplasmic reticulum (ER). Consistent with reports that prosurvival/physiologic UPR components are required for B-cell differentiation into antibody-secreting cells, we found that MM cells inherently expressed the ER chaperones GRP78/Bip and GRP94/gp96. However, bortezomib rapidly induced components of the proapoptotic/terminal UPR, including PERK, the ER stress-specific eIF-2alpha kinase; ATF4, an ER stress-induced transcription factor; and its proapoptotic target, CHOP/GADD153. Consistent with our hypothesis that PIs induce the accumulation of misfolded ER-processed proteins, we found that the amount of immunoglobulin subunits retained within MM cells correlated with their sensitivity to PIs. These findings suggest that MM cells have a lower threshold for PI-induced UPR induction and ER stress-induced apoptosis because they constitutively express ER stress survival factors to function as secretory cells.

Preferential in vivo DNA repair of melphalan-induced damage in human genes is greatly affected by the local chromatin structure

To investigate the molecular mechanisms of action of the nitrogen mustard melphalan in patients treated for multiple myeloma, the in vivo induction and repair of melphalan-induced DNA damage was measured in genes with different transcriptional activity (b-actin>p53>N-ras>d-globin) from leukocytes of 20 multiple myeloma patients following chemotherapeutic administration of high-dose melphalan (200mg/m(2)) and autologous blood stem cell transplantation. Heterogeneous repair was found among the studied genes. The extent of repair was always in the order: b-actin>p53>N-ras>d-globin, correlating with the gene transcriptional state. Similar findings were obtained using peripheral blood mononuclear cells (PBMC) from healthy volunteers following in vitro treatment with melphalan, indicating that these results are not malignant disease-specific. Following in vitro treatment of PBMC from healthy volunteers with alpha-amanitin, an inhibitor of RNA polymerase II that can also induce condensation of chromatin structure, a significant inhibition of the removal of melphalan-induced damage in the three active genes but not in the silent d-globin gene was found, suggesting that transcription and/or chromatin structure may play important roles in the preferential DNA repair. When the in vivo DNA damage formation and repair in multiple myeloma patients following chemotherapeutic administration of melphalan was measured in the two strands of the active genes, no strand bias was found, indicating that the global genome repair subpathway of nucleotide excision repair may play a crucial role in the repair of these adducts. These results were also confirmed in PBMC from healthy volunteers following in vitro treatment with melphalan. Using micrococcal nuclease digestion of nuclei isolated from PBMC of multiple myeloma patients before the chemotherapeutic treatment, as well as from PBMC of healthy volunteers, we probed the chromatin structure in each gene and found that the "looseness" of the chromatin structure correlated with the levels of the gene-specific repair, being again in the order: b-actin>p53>N-ras>d-globin. To conclude, the in vivo gene-specific repair of melphalan-induced damage in humans is greatly affected by the local chromatin structure.

Advances in the management of myeloma bone disease

Multiple myeloma is the second most common adult haematological malignancy. One of the major clinical features is the development of a unique osteolytic bone disease, characterised by progressive and devastating bone destruction, bone pain, pathological fractures and hypercalcaemia. Bisphosphonates, inhibitors of osteoclastic bone resorption, are the standard therapy for myeloma-induced bone disease. However, as our understanding of the molecular mechanisms involved in the development of myeloma bone disease increases, new molecular targets have been identified for the treatment of this devastating bone disease.

Myeloma bone disease: pathogenetic mechanisms and clinical assessment

Bone disease in multiple myeloma (MM) leads to progressive devastation of the skeleton and is the most severe cause of morbidity. Its pathogenetic mechanisms are not fully defined, though the current evidence points to hyperactivation of osteoclasts (OC) in presence of a major defect of bone repairing in erosion sites due to osteoblast (OB) impairment. Bone resorption, however, is promoted by early OB, namely stromal cells that respond to chronic stimulation by myeloma cells by enhancing marrow levels of RANKL and other osteoclastogenic factors and thus accelerating the maturation of OC progenitors. In myeloma bone disease (MBD), OBs are systematically defeated by a number of inhibiting effects induced by the malignant clone within the marrow microenvironment. Thus, MBD primarily affects the OB lineage, particularly in overt MM, where serum markers of osteoblastogenesis, such as osteocalcin and osteoprotegerin, are extremely low in contrast with their slight increase in inactive MM. These markers, in association with others of bone turnover (RANKL, MIP-1alpha, type I collagen telopeptides such as NTX and CTX) may be used in the clinical assessment of MBD as well as to monitor the efficacy of bisphosphonate in delaying the progressive skeletal destruction.

Thalidomide and lenalidomide in the treatment of multiple myeloma

Although multiple myeloma (MM) is incurable with currently available treatments, the introduction of thalidomide and the development of safer and more active thalidomide analogues represent a major advance in the therapy of this disease. Thalidomide, initially introduced for treatment of MM because of its anti-angiogenic properties, has shown remarkable activity alone and in combination with other drugs in patients across all stages of the disease. Given the potential for teratogenicity with thalidomide and the non-haematologic toxicities of the drug, several analogues referred to as "immunomodulatory drugs" (IMiDs) were developed with the intent of enhancing the immunomodulatory effect while minimizing the teratogenic risk. Lenalidomide (CC-5013) and Actimid (CC-4047) are the first such analogues to undergo clinical testing. Lenalidomide has shown impressive activity in relapsed refractory myeloma as well as newly diagnosed disease. The precise mechanism of anti-MM activity of thalidomide and the IMiDs is not clear, but studies suggest that several other mechanisms besides anti-angiogenic effects may play a role. In this paper we review the development, pharmacology, mechanism of action, pre-clinical and clinical efficacy, and the current status of thalidomide and the IMiDs in the treatment of MM.

Frequency, characteristics, and reversibility of peripheral neuropathy during treatment of advanced multiple myeloma with bortezomib

PURPOSE

To determine the frequency, characteristics, and reversibility of peripheral neuropathy from bortezomib treatment of advanced multiple myeloma.

PATIENTS AND METHODS

Peripheral neuropathy was assessed in two phase II studies in 256 patients with relapsed and/or refractory myeloma treated with bortezomib 1.0 or 1.3 mg/m2 intravenous bolus on days 1, 4, 8, and 11, every 21 days, for up to eight cycles. Peripheral neuropathy was evaluated at baseline, during the study, and after the study by patient-reported symptoms using the Functional Assessment of Cancer Therapy Scale/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-Ntx) questionnaire and neurologic examination. During the study, peripheral neuropathy was also evaluated by investigator assessment. A subset of patients underwent nerve conduction studies (n = 13).

RESULTS

Before treatment, 194 (81%) of 239 patients had peripheral neuropathy by FACT/GOG-Ntx questionnaire, and 203 (83%) of 244 patients had peripheral neuropathy by neurologic examination. Treatment-emergent neuropathy was reported in 35% of patients, including 37% (84 of 228 patients) receiving bortezomib 1.3 mg/m2 and 21% (six of 28 patients) receiving bortezomib 1.0 mg/m2. Grade 1 or 2, 3, and 4 neuropathy occurred in 22%, 13%, and 0.4% of patients, respectively. The incidence of grade > or = 3 neuropathy was higher among patients with baseline neuropathy by FACT/GOG-Ntx questionnaire compared with patients without baseline neuropathy (14% v 4%, respectively). In all 256 patients, neuropathy led to dose reduction in 12% and discontinuation in 5%. Of 35 patients with neuropathy > or = grade 3 and/or requiring discontinuation, resolution to baseline or improvement occurred in 71%.

CONCLUSION

Bortezomib-associated peripheral neuropathy seemed reversible in the majority of patients after dose reduction or discontinuation. Although severe neuropathy was more frequent in the presence of baseline neuropathy, the overall occurrence was independent of baseline neuropathy or type of prior therapy.

Complete response in multiple myeloma: clinical trial E9486, an Eastern Cooperative Oncology Group study not involving stem cell transplantation

BACKGROUND

The importance of obtaining a complete response (CR) in multiple myeloma (MM) treated with chemotherapy is unclear.

METHODS

The Eastern Cooperative Oncology Group evaluated 653 previously untreated patients with active MM randomized to vincristine, carmustine (BCNU), melphalan, cyclophosphamide, and prednisone (VBMCP), to VBMCP and recombinant interferon alfa-2 (INFalpha-2), or to VBMCP and high-dose cyclophosphamide.

RESULTS

Objective response was achieved in 420 (67%) of the 628 eligible patients, and 85 (14%) achieved a CR. Patients receiving VBMCP and recombinant INFalpha-2 had a significantly higher CR (18%) than those receiving VBMCP alone (10%) (P = .02). The CR rate for VBMCP and high-dose cyclophosphamide was 12%. Median duration of survival was 3.5 years for all eligible patients, and the estimated 5-year survival rate was 31%. The median duration of survival from the date of objective response was 5.1 years for those who achieved a CR and 3.3 years for those with a partial response (P < .0001). The median postresponse survival was 6.6 years in the 21 patients in CR with nonclonal disease and 4.4 years in the 11 patients in CR who had persistent clonal disease. All patients with negative immunofixation results and nonclonal plasma cells in whom polymerase chain reaction was performed had a positive result (presence of tumor DNA).

CONCLUSION

Patients in whom a CR was achieved had a longer survival than those who had a partial response.

LAGlambda-1: a clinically relevant drug resistant human multiple myeloma tumor murine model that enables rapid evaluation of treatments for multiple myeloma

We set out to generate new human myeloma tumors that grow in immunodeficient mice and can be used for pathophysiological studies and rapid evaluation of new therapies. Fresh whole core bone marrow (BM) biopsies taken from 33 myeloma patients were engrafted into the hind limb muscle of severe combined immunodeficient (SCID) mice. Human Ig was detected in 28/33 mice and three grew palpable tumors displaying many features of human myeloma including morphology, immunophenotype and BM plasmacytosis. Following intramuscular passage, we generated large numbers of mice with predictable increases in tumor growth and human paraprotein levels. We further characterized the model generated from an IgGlambda-producing tumor known as LAGlambda-1 and determined the effects of the proteasome inhibitor bortezomib, the alkylating agent melphalan, and the DNA damaging agent liposomal doxorubicin, on the growth of this tumor. LAGlambda-1-bearing mice receiving higher doses of bortezomib showed reduced tumor growth whereas a lower dose had no effect. In contrast, melphalan did not significantly alter tumor growth, except minimally at high doses, reflecting the resistance of this patient's tumor to this drug. We also used our intramuscular (i.m.) LAGlambda-1 model to optimize the dosing schedule of liposomal doxorubicin. Low doses administered once daily three days per week decreased tumor growth and human paraprotein levels whereas much higher doses given once weekly had no anti-myeloma effects. Furthermore, LAGlambda-1 cells produce local tumors when injected subcutaneously and lytic lesions when injected intravenously allowing for multiple methods of evaluating the anti-myeloma effects of a variety of agents. Our new clinically relevant SCID models of human myeloma should greatly facilitate drug development and enable novel therapies to quickly move from the laboratory to the clinic.

A smoldering/indolent myeloma with extensive abdominal presentation--case report

A case of indolent/smoldering myeloma in a 70-year-old man is reported. He presented with an unusual multiple symptomatic myeloma with extramedulary impairment and absence of bone pain. He was treated with pulses of high-dose dexamethasone with commendable clinical improvement.

Combination chemotherapy with cyclophosphamide, thalidomide and dexamethasone for patients with refractory, newly diagnosed or relapsed myeloma

We evaluated the combination of thalidomide, pulsed dexamethasone and weekly cyclophosphamide (CTD) for the treatment of patients with newly diagnosed, relapsed or VAD-refractory multiple myeloma. We found that this combination was highly effective in inducing responses in all treatment groups with an overall response rate of 83.8%. CTD was well tolerated and did not impair stem cell mobilization.

Targeting signalling pathways for the treatment of multiple myeloma

Multiple myeloma (MM) is characterised by the expansion of monoclonal immunoglobulin-secreting plasma cells. Despite recent advances in systemic and supportive therapy, it remains incurable, with a median survival of about three years. Development of MM is a multistep process associated with an increasing frequency of chromosomal abnormalities and complex translocations, which induce mutations in several proto-oncogenes and tumour suppressor genes. Furthermore, differentiation, maintenance, expansion and drug resistance of MM cells are dependent on multiple growth factors, cytokines, and chemokines, secreted by tumour cells, bone marrow stromal cells, and non-haematopoietic organs; as well as on direct tumour cell-stromal cell contact. Therefore, signalling pathways initiated by both mutated genes in MM cells as well as signals originating in the bone marrow microenvironment represent potential targets for intervention. Close collaboration between basic researchers and clinicians will be required to further improve our knowledge of MM pathophysiologically in order to translate advances from the bench to the bedside and improve patient outcome.

[Plasmacytoma with multiple hypervascular lesions revealed by angiography in a patient with multiple myeloma]

A 68-year-old woman suffering from a left iliac tumor and severe back pain was admitted to another hospital in May 1999. The bone X-ray, CT scan and MRI demonstrated a 7 cm x 5 cm left iliac tumor with osteolysis and she was transferred to our hospital. Angiography demonstrated multiple hypervascular lesions in the left ilium, lumbar vertebrae, left ischium, left pubis and left rib. The tumor was resected and diagnosed as a plasmacytoma. Immunoelectrophoresis did not show any M-protein in the serum and urine, but the patient was diagnosed as having a non-secretory or low producing multiple myeloma because of the presence of 42.8% of abnormal plasma cells in the bone marrow aspirate. Her symptoms improved following 3 courses of MCNU-VMP therapy and the bone marrow plasma cells decreased to less than 5%. She was discharged and treated as an outpatient but relapsed and died of chemotherapy-resistant myeloma. We report this case because macro-angiogenesis in a multiple myeloma demonstrated by angiography is rare and interesting.