IDH2 mutation-induced histone and DNA hypermethylation is progressively reversed by small-molecule inhibition.

Mutations of IDH1 and IDH2, which produce the oncometabolite 2-hydroxyglutarate (2HG), have been identified in several tumors, including acute myeloid leukemia. Recent studies have shown that expression of the IDH mutant enzymes results in high levels of 2HG and a block in cellular differentiation that can be reversed with IDH mutant-specific small-molecule inhibitors. To further understand the role of IDH mutations in cancer, we conducted mechanistic studies in the TF-1 IDH2 R140Q erythroleukemia model system and found that IDH2 mutant expression caused both histone and genomic DNA methylation changes that can be reversed when IDH2 mutant activity is inhibited. Specifically, histone hypermethylation is rapidly reversed within days, whereas reversal of DNA hypermethylation proceeds in a progressive manner over the course of weeks. We identified several gene signatures implicated in tumorigenesis of leukemia and lymphoma, indicating a selective modulation of relevant cancer genes by IDH mutations. As methylation of DNA and histones is closely linked to mRNA expression and differentiation, these results indicate that IDH2 mutant inhibition may function as a cancer therapy via histone and DNA demethylation at genes involved in differentiation and tumorigenesis.

Isocitrate dehydrogenase 1 (IDH1) mutation in breast adenocarcinoma is associated with elevated levels of serum and urine 2-hydroxyglutarate.

Mutations in the IDH1 and IDH2 (isocitrate dehydrogenase) genes have been discovered across a range of solid-organ and hematologic malignancies, including acute myeloid leukemia, glioma, chondrosarcoma, and cholangiocarcinoma. An intriguing aspect of IDH-mutant tumors is the aberrant production and accumulation of the oncometabolite 2-hydroxyglutarate (2-HG), which may play a pivotal oncogenic role in these malignancies. We describe the first reported case of an IDH1 p.R132L mutation in a patient with hormone receptor-positive (HR+) breast adenocarcinoma. This patient was initially treated for locally advanced disease, but then suffered a relapse and metastasis, at which point an IDH1-R132 mutation was discovered in an affected lymph node. The mutation was subsequently found in the primary tumor tissue and all metastatic sites, but not in an uninvolved lymph node. In addition, the patient's serum and urine displayed marked elevations in the concentration of 2-HG, significantly higher than that measured in six other patients with metastatic HR+ breast carcinoma whose tumors were found to harbor wild-type IDH1. In summary, IDH1 mutations may impact a rare subgroup of patients with breast adenocarcinoma. This may suggest future avenues for disease monitoring through noninvasive measurement of 2-HG, as well as for the development and study of targeted therapies against the aberrant IDH1 enzyme.

Prospective serial evaluation of 2-hydroxyglutarate, during treatment of newly diagnosed acute myeloid leukemia, to assess disease activity and therapeutic response.

Mutations of genes encoding isocitrate dehydrogenase (IDH1 and IDH2) have been recently described in acute myeloid leukemia (AML). Serum and myeloblast samples from patients with IDH-mutant AML contain high levels of the metabolite 2-hydroxyglutarate (2-HG), a product of the altered IDH protein. In this prospective study, we sought to determine whether 2-HG can potentially serve as a noninvasive biomarker of disease burden through serial measurements in patients receiving conventional therapy for newly diagnosed AML. Our data demonstrate that serum, urine, marrow aspirate, and myeloblast 2-HG levels are significantly higher in IDH-mutant patients, with a correlation between baseline serum and urine 2-HG levels. Serum and urine 2-HG, along with IDH1/2-mutant allele burden in marrow, decreased with response to treatment. 2-HG decrease was more rapid with induction chemotherapy compared with DNA-methyltransferase inhibitor therapy. Our data suggest that serum or urine 2-HG may serve as noninvasive biomarkers of disease activity for IDH-mutant AML.

Enasidenib treatment in two individuals with D-2-hydroxyglutaric aciduria carrying a germline IDH2 mutation.

D-2-hydroxyglutaric aciduria type II (D2HGA2) is a severe inborn disorder of metabolism caused by heterozygous R140 mutations in the IDH2 (isocitrate dehydrogenase 2) gene. Here we report the results of treatment of two children with D2HGA2, one of whom exhibited severe dilated cardiomyopathy, with the selective mutant IDH2 enzyme inhibitor enasidenib. In both children, enasidenib treatment led to normalization of D-2-hydroxyglutarate (D-2-HG) concentrations in body fluids. At doses of 50 mg and 60 mg per day, no side effects were observed, except for asymptomatic hyperbilirubinemia. For the child with cardiomyopathy, chronic D-2-HG inhibition was associated with improved cardiac function, and for both children, therapy was associated with improved daily functioning, global motility and social interactions. Treatment of the child with cardiomyopathy led to therapy-coordinated changes in serum phospholipid levels, which were partly recapitulated in cultured fibroblasts, associated with complex effects on lipid and redox-related gene pathways. These findings indicate that targeted inhibition of a mutant enzyme can partly reverse the pathology of a chronic neurometabolic genetic disorder.

Frequent mutation of isocitrate dehydrogenase (IDH)1 and IDH2 in cholangiocarcinoma identified through broad-based tumor genotyping.

Cancers of origin in the gallbladder and bile ducts are rarely curable with current modalities of cancer treatment. Our clinical application of broad-based mutational profiling for patients diagnosed with a gastrointestinal malignancy has led to the novel discovery of mutations in the gene encoding isocitrate dehydrogenase 1 (IDH1) in tumors from a subset of patients with cholangiocarcinoma. A total of 287 tumors from gastrointestinal cancer patients (biliary tract, colorectal, gastroesophageal, liver, pancreatic, and small intestine carcinoma) were tested during routine clinical evaluation for 130 site-specific mutations within 15 cancer genes. Mutations were identified within a number of genes, including KRAS (35%), TP53 (22%), PIK3CA (10%), BRAF (7%), APC (6%), NRAS (3%), AKT1 (1%), CTNNB1 (1%), and PTEN (1%). Although mutations in the metabolic enzyme IDH1 were rare in the other common gastrointestinal malignancies in this series (2%), they were found in three tumors (25%) of an initial series of 12 biliary tract carcinomas. To better define IDH1 and IDH2 mutational status, an additional 75 gallbladder and bile duct cancers were examined. Combining these cohorts of biliary cancers, mutations in IDH1 and IDH2 were found only in cholangiocarcinomas of intrahepatic origin (nine of 40, 23%) and in none of the 22 extrahepatic cholangiocarcinomas and none of the 25 gallbladder carcinomas. In an analysis of frozen tissue specimens, IDH1 mutation was associated with highly elevated tissue levels of the enzymatic product 2-hydroxyglutarate. Thus, IDH1 mutation is a molecular feature of cholangiocarcinomas of intrahepatic origin. These findings define a specific metabolic abnormality in this largely incurable type of gastrointestinal cancer and present a potentially new target for therapy.

Non-invasive detection of 2-hydroxyglutarate and other metabolites in IDH1 mutant glioma patients using magnetic resonance spectroscopy.

Mutations of the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) are commonly found in primary brain cancers. We previously reported that a novel enzymatic activity of these mutations results in the production of the putative oncometabolite, R(-)-2-hydroxyglutarate (2-HG). Here we investigated the ability of magnetic resonance spectroscopy (MRS) to detect 2-HG production in order to non-invasively identify patients with IDH1 mutant brain tumors. Patients with intrinsic glial brain tumors (n = 27) underwent structural and spectroscopic magnetic resonance imaging prior to surgery. 2-HG levels from MRS data were quantified using LC-Model software, based upon a simulated spectrum obtained from a GAMMA library added to the existing prior knowledge database. The resected tumors were then analyzed for IDH1 mutational status by genomic DNA sequencing, Ki-67 proliferation index by immunohistochemistry, and concentrations of 2-HG and other metabolites by liquid chromatography-mass spectrometry (LC-MS). MRS detected elevated 2-HG levels in gliomas with IDH1 mutations compared to those with wild-type IDH1 (P = 0.003). The 2-HG levels measured in vivo with MRS were significantly correlated with those measured ex vivo from the corresponding tumor samples using LC-MS (r (2) = 0.56; P = 0.0001). Compared with wild-type tumors, those with IDH1 mutations had elevated choline (P = 0.01) and decreased glutathione (P = 0.03) on MRS. Among the IDH1 mutated gliomas, quantitative 2-HG values were correlated with the Ki-67 proliferation index of the tumors (r ( 2 ) = 0.59; P = 0.026). In conclusion, water-suppressed proton ((1)H) MRS provides a non-invasive measure of 2-HG in gliomas, and may serve as a potential biomarker for patients with IDH1 mutant brain tumors. In addition to 2-HG, alterations in several other metabolites measured by MRS correlate with IDH1 mutation status.

Phase I and pharmacokinetic study of bortezomib in combination with idarubicin and cytarabine in patients with acute myelogenous leukemia.

PURPOSE: Proteasome inhibition results in cytotoxicity to the leukemia stem cell in vitro. We conducted this phase I study to determine if the proteasome inhibitor bortezomib could be safely added to induction chemotherapy in patients with acute myelogenous leukemia (AML). EXPERIMENTAL DESIGN: Bortezomib was given on days 1, 4, 8, and 11 at doses of 0.7, 1.0, 1.3, or 1.5 mg/m(2) with idarubicin 12 mg/m(2) on days 1 to 3 and cytarabine 100 mg/m(2)/day on days 1 to 7. RESULTS: A total of 31 patients were enrolled. The median age was 62 years, and 16 patients were male. Nine patients had relapsed AML (ages, 18-59 years, n = 4 and > or = 60 years, n = 5). There were 22 patients of > or = 60 years with previously untreated AML (eight with prior myelodysplasia/myeloproliferative disorder or cytotoxic therapy). All doses of bortezomib, up to and including 1.5 mg/m(2), were tolerable. Nonhematologic grade 3 or greater toxicities included 12 hypoxia (38%; 11 were grade 3), 4 hyperbilirubinemia (13%), and 6 elevated aspartate aminotransferase (19%). Overall, 19 patients (61%) achieved complete remission (CR) and three had CR with incomplete platelet recovery. Pharmacokinetic studies revealed that the total body clearance of bortezomib decreased significantly (P < 0.01, N = 26) between the first (mean +/- SD, 41.9 +/- 17.1 L/h/m(2)) and third (18.4 +/- 7.0 L/h/m(2)) doses. Increased bone marrow expression of CD74 was associated with CR. CONCLUSIONS: The combination of bortezomib, idarubicin, and cytarabine showed a good safety profile. The recommended dose of bortezomib for phase II studies with idarubicin and cytarabine is 1.5 mg/m(2).

The proteasome inhibitor bortezomib acts independently of p53 and induces cell death via apoptosis and mitotic catastrophe in B-cell lymphoma cell lines.

Bortezomib is a proteasome inhibitor with proven efficacy in multiple myeloma and non-Hodgkin's lymphoma. This study reports the effects of bortezomib in B-cell lymphoma cell lines with differing sensitivity to bortezomib to investigate factors that influence sensitivity. Bortezomib induced a time- and concentration-dependent reduction in cell viability in five lymphoma cell lines, with EC(50) values ranging from 6 nmol/L (DHL-7 cells) to 25 nmol/L (DHL-4 cells) after 72 h. Bortezomib cytotoxicity was independent of p53 function, as all cell lines exhibited mutations by sequence analysis. The difference in sensitivity was not explained by proteasome or nuclear factor-kappaB (NF-kappaB) inhibition as these were similar in the most and least sensitive cells. NF-kappaB inhibition was less marked than that of a specific NF-kappaB inhibitor, Bay 11-7082. Cell cycle analysis showed a marked G(2)-arrested population in the least sensitive DHL-4 line only, an effect that was not present with Bay 11-7082 treatment. Conversely, in DHL-7 cells, bortezomib treatment resulted in cells moving into an aberrant mitosis, indicative of mitotic catastrophe that may contribute to increased sensitivity to bortezomib. These studies show that although bortezomib treatment had similar effects on apoptotic and NF-kappaB signaling pathways in these cell lines, different cell cycle effects were observed and induction of a further mechanism of cell death, mitotic catastrophe, was observed in the more sensitive cell line, which may provide some pointers to the difference in sensitivity between cell lines. An improved understanding of how DHL-7 cells abrogate the G(2)-M cell cycle checkpoint may help identify targets to increase the efficacy of bortezomib.

Bortezomib or high-dose dexamethasone for relapsed multiple myeloma.

BACKGROUND: This study compared bortezomib with high-dose dexamethasone in patients with relapsed multiple myeloma who had received one to three previous therapies. METHODS: We randomly assigned 669 patients with relapsed myeloma to receive either an intravenous bolus of bortezomib (1.3 mg per square meter of body-surface area) on days 1, 4, 8, and 11 for eight three-week cycles, followed by treatment on days 1, 8, 15, and 22 for three five-week cycles, or high-dose dexamethasone (40 mg orally) on days 1 through 4, 9 through 12, and 17 through 20 for four five-week cycles, followed by treatment on days 1 through 4 for five four-week cycles. Patients who were assigned to receive dexamethasone were permitted to cross over to receive bortezomib in a companion study after disease progression. RESULTS: Patients treated with bortezomib had higher response rates, a longer time to progression (the primary end point), and a longer survival than patients treated with dexamethasone. The combined complete and partial response rates were 38 percent for bortezomib and 18 percent for dexamethasone (P<0.001), and the complete response rates were 6 percent and less than 1 percent, respectively (P<0.001). Median times to progression in the bortezomib and dexamethasone groups were 6.22 months (189 days) and 3.49 months (106 days), respectively (hazard ratio, 0.55; P<0.001). The one-year survival rate was 80 percent among patients taking bortezomib and 66 percent among patients taking dexamethasone (P=0.003), and the hazard ratio for overall survival with bortezomib was 0.57 (P=0.001). Grade 3 or 4 adverse events were reported in 75 percent of patients treated with bortezomib and in 60 percent of those treated with dexamethasone. CONCLUSIONS: Bortezomib is superior to high-dose dexamethasone for the treatment of patients with multiple myeloma who have had a relapse after one to three previous therapies.

A phase 2 study of bortezomib in relapsed, refractory myeloma.

BACKGROUND: Bortezomib, a boronic acid dipeptide, is a novel proteasome inhibitor that has been shown in preclinical and phase 1 studies to have antimyeloma activity. METHODS: In this multicenter, open-label, nonrandomized, phase 2 trial, we enrolled 202 patients with relapsed myeloma that was refractory to the therapy they had received most recently. Patients received 1.3 mg of bortezomib per square meter of body-surface area twice weekly for 2 weeks, followed by 1 week without treatment, for up to eight cycles (24 weeks). In patients with a suboptimal response, oral dexamethasone (20 mg daily, on the day of and the day after bortezomib administration) was added to the regimen. The response was evaluated according to the criteria of the European Group for Blood and Marrow Transplantation and confirmed by an independent review committee. RESULTS: Of 193 patients who could be evaluated, 92 percent had been treated with three or more of the major classes of agents for myeloma, and in 91 percent, the myeloma was refractory to the therapy received most recently. The rate of response to bortezomib was 35 percent, and those with a response included 7 patients in whom myeloma protein became undetectable and 12 in whom myeloma protein was detectable only by immunofixation. The median overall survival was 16 months, with a median duration of response of 12 months. Grade 3 adverse events included thrombocytopenia (in 28 percent of patients), fatigue (in 12 percent), peripheral neuropathy (in 12 percent), and neutropenia (in 11 percent). Grade 4 events occurred in 14 percent of patients. CONCLUSIONS: Bortezomib, a member of a new class of anticancer drugs, is active in patients with relapsed multiple myeloma that is refractory to conventional chemotherapy.

MLN120B, a novel IkappaB kinase beta inhibitor, blocks multiple myeloma cell growth in vitro and in vivo.

PURPOSE: The purpose of this study is to delineate the biological significance of IkappaB kinase (IKK) beta inhibition in multiple myeloma cells in the context of bone marrow stromal cells (BMSC) using a novel IKKbeta inhibitor MLN120B. EXPERIMENTAL DESIGN: Growth-inhibitory effect of MLN120B in multiple myeloma cells in the presence of cytokines [interleukin-6 (IL-6) and insulin-like growth factor-I (IGF-1)], conventional agents (dexamethasone, melphalan, and doxorubicin), or BMSC was assessed in vitro. In vivo anti-multiple myeloma activity of MLN120B was evaluated in severe combined immunodeficient (SCID)-hu model. RESULTS: MLN120B inhibits both baseline and tumor necrosis factor-alpha-induced nuclear factor-kappaB activation, associated with down-regulation of IkappaBalpha and p65 nuclear factor-kappaB phosphorylation. MLN120B triggers 25% to 90% growth inhibition in a dose-dependent fashion in multiple myeloma cell lines and significantly augments tumor necrosis factor-alpha-induced cytotoxicity in MM.1S cells. MLN120B augments growth inhibition triggered by doxorubicin and melphalan in both RPMI 8226 and IL-6-dependent INA6 cell lines. Neither IL-6 nor IGF-1 overcomes the growth-inhibitory effect of MLN120B. MLN120B inhibits constitutive IL-6 secretion by BMSCs by 70% to 80% without affecting viability. Importantly, MLN120B almost completely blocks stimulation of MM.1S, U266, and INA6 cell growth, as well as IL-6 secretion from BMSCs, induced by multiple myeloma cell adherence to BMSCs. MLN120B overcomes the protective effect of BMSCs against conventional (dexamethasone) therapy. CONCLUSIONS: Our data show that the novel IKKbeta inhibitor MLN120B induces growth inhibition of multiple myeloma cells in SCID-hu mouse model. These studies provide the framework for clinical evaluation of MLN120B, alone and in combined therapies, trials of these novel agents to improve patient outcome in multiple myeloma.

Phase II clinical experience with the novel proteasome inhibitor bortezomib in patients with indolent non-Hodgkin's lymphoma and mantle cell lymphoma.

PURPOSE: To determine the antitumor activity of the novel proteasome inhibitor bortezomib in patients with indolent and mantle-cell lymphoma (MCL). PATIENTS AND METHODS: Patients with indolent and MCL were eligible. Bortezomib was given at a dose of 1.5 mg/m2 on days 1, 4, 8, and 11. Patients were required to have received no more than three prior chemotherapy regimens, with at least 1 month since the prior treatment, 3 months from prior rituximab, and 7 days from prior corticosteroids; absolute neutrophil count more than 1,500/microL (500/microL if documented bone marrow involvement); and platelet count more than 50,000/microL. RESULTS: Twenty-six patients were registered, of whom 24 were assessable. Ten patients had follicular lymphoma, 11 had MCL, three had small lymphocytic lymphoma (SLL) or chronic lymphocytic leukemia (CLL), and two had marginal zone lymphoma. The overall response rate was 58%, with one complete remission (CR), one unconfirmed CR (CRu), and four partial remissions (PR) among patients with follicular non-Hodgkin's lymphoma (NHL). All responses were durable, lasting from 3 to 24+ months. One patient with MCL achieved a CRu, four achieved a PR, and four had stable disease. One patient with MCL maintained his remission for 19 months. Both patients with marginal zone lymphoma achieved PR lasting 8+ and 11+ months, respectively. Patients with SLL or CLL have yet to respond. Overall, the drug was well tolerated, with only one grade 4 toxicity (hyponatremia). The most common grade 3 toxicities were lymphopenia (n = 14) and thrombocytopenia (n = 7). CONCLUSION: These data suggest that bortezomib was well tolerated and has significant single-agent activity in patients with certain subtypes of NHL.

Phase II study of proteasome inhibitor bortezomib in relapsed or refractory B-cell non-Hodgkin's lymphoma.

PURPOSE: Evaluate efficacy and toxicity of bortezomib in patients with relapsed or refractory B-cell non-Hodgkin's lymphoma. PATIENTS AND METHODS: Patients were stratified, based on preclinical data, into arm A (mantle-cell lymphoma) or arm B (other B-cell lymphomas) without limitation in number of prior therapies. Bortezomib was administered as an intravenous push (1.5 mg/m2) on days 1, 4, 8, and 11 every 21 days for a maximum of six cycles. RESULTS: Sixty patients with a median number of prior therapies of 3.5 (range, one to 12 therapies) were enrolled; 33 patients were in arm A and 27 were in arm B, including 12 diffuse large B-cell lymphomas, five follicular lymphomas (FL), three transformed FLs, four small lymphocytic lymphomas (SLL), two Waldenstrom's macroglobulinemias (WM), and one marginal zone lymphoma. In arm A, 12 of 29 assessable patients responded (six complete responses [CR] and six partial responses [PR]) for an overall response rate (ORR) of 41% (95% CI, 24% to 61%), and a median time to progression not reached yet, with a median follow-up of 9.3 months (range, 1.7 to 24 months). In arm B, four of 21 assessable patients responded (one SLL patient had a CR, one FL patient had a CR unconfirmed, one diffuse large B-cell lymphoma patient had a PR, and one WM patient had a PR) for an ORR of 19% (95% CI, 5% to 42%). Grade 3 toxicity included thrombocytopenia (47%), gastrointestinal (20%), fatigue (13%), neutropenia (10%), and peripheral neuropathy (5%). Grade 4 toxicity occurred in nine patients (15%), and three deaths from progression of disease occurred within 30 days of withdrawal from study. CONCLUSION: Bortezomib showed promising activity in relapsed mantle-cell lymphoma and encouraging results in other B-cell lymphomas. Future studies will explore bortezomib in combination with other cytotoxic or biologic agents.

Bortezomib in combination with dexamethasone for the treatment of patients with relapsed and/or refractory multiple myeloma with less than optimal response to bortezomib alone.

BACKGROUND AND OBJECTIVES: The efficacy and safety of added dexamethasone were assessed in patients with relapsed and/or refractory multiple myeloma who had a suboptimal response to bortezomib alone. DESIGN AND METHODS: In two previously reported, open-label, multicenter phase 2 studies, bortezomib 1.0 or 1.3 mg/m2 was administered intravenously twice weekly for 2 weeks of a 3-week cycle for up to 8 cycles to patients who had failed either > or = 2 lines of therapy (SUMMIT, n=202) or first-line therapy (CREST, n=54). Patients with progressive disease after the first two cycles or stable disease after four cycles of bortezomib were eligible for addition of oral dexamethasone 20 mg on the day of and after each bortezomib dose. Responses were assessed by an Independent Review Committee using European Group for Blood and Marrow Transplantation criteria. RESULTS: Addition of dexamethasone to bortezomib was associated with improved responses in 13 of 74 evaluable patients (18%) in SUMMIT and 9 of 27 (33%) in CREST; eight of these 22 patients had been previously refractory to dexamethasone. There were 2 complete, 8 partial, and 12 minimal responses. Dexamethasone did not appear to alter the type or number of adverse events. Treatment-emergent adverse events reported in > or = 20% of patients receiving combination therapy were fatigue (25%), thrombocytopenia (24%), insomnia (21%), and nausea (20%). INTERPRETATION AND CONCLUSIONS: Addition of dexamethasone to bortezomib in patients with relapsed and/or refractory myeloma who had suboptimal responses to bortezomib alone was associated with improvement in responses without prohibitive toxicity.

Preclinical data with bortezomib in lung cancer.

More effective therapies are needed for non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Proteasome inhibitors are one class of molecularly targeted antineoplastic agents being investigated for these diseases. These agents block the activity of the 26S proteasome, which is responsible for the degradation of the vast majority of intracellular proteins and thus affect multiple signaling pathways within cells. Bortezomib is the first proteasome inhibitor to be evaluated in human studies and is approved for use in multiple myeloma. Bortezomib is now being investigated as a potential treatment for NSCLC and SCLC. Preclinical studies have shown that single-agent bortezomib causes growth inhibition and apoptosis in numerous NSCLC cell lines in vitro and has antitumor activity in vivo. Bortezomib affects the levels of several proteins known to be of significance in lung cancers. Studies of bortezomib in combination with other antitumor agents in vitro and in vivo demonstrate that these combination regimens can offer additive/synergistic effects compared with the single agents. Bortezomib has been investigated in combination with taxanes, gemcitabine, carboplatin, histone deactylase inhibitors, and other molecularly targeted agents in various NSCLC cell lines. The sequence of administration of the agents in preclinical combination regimens in vitro and in vivo has been shown to be of significance; further elucidation of the mechanism of efficacy of bortezomib in lung cancer is required. Numerous clinical studies have been carried out or are ongoing. Bortezomib has the potential to play a significant role in the future management of NSCLC and SCLC.

CD20-Directed Antibody-Mediated Immunotherapy Induces Responses and Facilitates Hematologic Recovery in Patients With Waldenstrom's Macroglobulinemia.

SUMMARY: Waldenstrom's macroglobulinemia (WM, lymphoplasmacytic lymphoma) is a B-cell lymphoproliferative disorder in which CD20 is expressed on tumor cells from most patients. Several small studies have suggested a benefit from the anti-CD20 monoclonal antibody rituximab (Rituxan, MabThera) in patients with WM. In this retrospective study, we examined the outcome of 30 previously unreported patients with WM who received treatment with single-agent rituximab (median age 60; range 32-83 years old). The median number of prior treatments for these patients was 1 (range 0-6), and 14 patients (47%) received a nucleoside analogue before rituximab therapy. Patients received a median of 4.0 (1-11.3) infusions of rituximab (375 mg/m2). Three patients received steroids with their infusions for prophylaxis of rituximab-related infusion syndrome. Overall, treatment was well tolerated. Median immunoglobulin M (IgM) levels for all patients declined from 2,403 mg/dL (range 720-7639 mg/dL) to 1,525 mg/dL (range 177-5,063 mg/dL) after rituximab therapy (p = 0.001), with 8 of 30 (27%) and 18 of 30 (60%) patients demonstrating >50% and >25% decline in IgM, respectively. Median bone marrow lymphoplasmacytic (BM LPC) cell involvement declined from 60% (range 5-90%) to 15% (range 0-80%) for 17 patients for whom pre-and post-BM biopsies were performed (p < 0.001). Moreover, 19 of 30 (63%) and 15 of 30 (50%) patients had an increase in their hematocrit (HCT) and platelet (PLT) counts, respectively. Before rituximab therapy, 7 of 30 (23.3%) patients were either transfusion or erythropoietin dependent, whereas only 1/30 (3.3%) patients required transfusions (no erythropoietin) after rituximab. Overall responses after treatment with rituximab were as follows: 8 (27%) and 10 (33%) of the patients achieved a partial (PR) and a minor (MR) response, respectively, and an additional 9 (30%) of patients demonstrated stable disease (SD). No patients attained a complete response. The median time to treatment failure for responding (PR and MR) patients was 8.0 months (mean 8.4; range 3-20+ months), and 5.0 months (mean 6.1; range 3-12+ months) for patients with SD. These studies therefore demonstrate that rituximab is an active agent in WM. Marked increases in HCT and PLT counts were noted for most patients, including patients with WM who had MR or SD. A prospective clinical trial to more completely define the benefit of single-agent rituximab in patients with WM has been initiated by many of our centers.

Targeted therapies for cancer 2004.

The regulatory agency approvals in the United States and Europe of imatinib mesylate (Gleevec) for patients with bcr/abl-positive chronic myelogenous leukemia, cetuximab (Erbitux) for patients with epidermal growth factor receptor overexpressing metastatic colorectal cancer, the antiangiogenesis agent bevacizumab (Avastin), and the proteasome inhibitor bortezomib (Velcade)--and the considerable public interest in new anticancer drugs that take advantage of specific genetic defects that render the malignant cells more likely to respond to specific treatment--are driving a new era of integrated diagnostics and therapeutics. The recent discovery of a drug response predicting activating mutation in the epidermal growth factor receptor gene for patients with non-small cell lung cancer treated with gefitinib (Iressa) has intensified this interest. In this review, the history of targeted anticancer therapies is highlighted, with focus on the development of molecular diagnostics for hematologic malignancies and the emergence of trastuzumab (Herceptin), an antibody-based targeted therapy for HER-2/neu overexpressing metastatic breast cancer: The potential of pharmacogenomic strategies and the use of high-density genomic microarrays to classify and select therapy for cancer are briefly considered. This review also considers the widely held view that, in the next 5 to 10 years, the clinical application of molecular diagnostics will further revolutionize the drug discovery and development process; customize the selection, dosing, route of administration of existing and new therapeutic agents; and truly personalize medical care for cancer patients.

Proteasome inhibitors in the treatment of B-cell malignancies.

The proteasome, which plays a pivotal role in the control of many cell cycle-regulatory processes, has become the focus of new approaches to the treatment of cancer, including B-cell malignancies, and the first proteasome inhibitor, bortezomib (VELCADE; formerly PS-341), has entered clinical trials. The proteasome controls the stability of numerous proteins that regulate progression through the cell cycle and apoptosis, such as cyclins, cyclin-dependent kinases, tumor suppressors, and the nuclear factor-kB. By altering the stability or activity of these proteins, proteasome inhibitors sensitize malignant cells to apoptosis. Bortezomib is a dipeptidyl boronic acid proteasome inhibitor that effectively and specifically inhibits proteasome activity. In preclinical studies, bortezomib and other proteasome inhibitors have shown activity against a variety of B-cell malignancies, including multiple myeloma, diffuse large B-cell lymphoma, mantle cell lymphoma, and Hodgkin's lymphoma. These agents can induce apoptosis and sensitize tumor cells to radiation or chemotherapy. Based on these findings, phase I clinical trials were conducted with bortezomib in various solid and hematologic malignancies. In these studies, bortezomib was generally well tolerated with manageable toxicities. Phase II trials have been initiated for relapsed and refractory multiple myeloma, refractory chronic lymphocytic leukemia, and non-Hodgkin's lymphoma. Preliminary data from the multiple myeloma phase II study indicate that a significant number of patients responded to therapy or exhibited stable disease and that the drug had manageable toxicities. These findings, along with extensive preclinical data, suggest that bortezomib and other proteasome inhibitors may have far-reaching potential in the treatment of various cancers, including B-cell malignancies.

Use of proteasome inhibition in the treatment of lung cancer.

The proteasome plays a critical role in the degradation of proteins involved in the regulation of cell cycle, apoptosis, and angiogenesis. Bortezomib is the first in a new class of antineoplastic agents known as proteasome inhibitors to become available for clinical use. Bortezomib targets pathways relevant to tumor progression and therapy resistance and can directly modulate expression of cyclins, p27kip1, p53, nuclear factor-kB, Bcl-2, and Bax. In in vitro and in vivo, growth inhibition and apoptosis have been observed in tumor cells following exposure to bortezomib. Currently, bortezomib is approved for the treatment of patients with relapsed and/or refractory multiple myeloma who have received > or =2 therapies and progressed on their most recent therapy. Efforts are now being directed toward exploring the use of bortezomib in the treatment of advanced non-small-cell lung cancer (NSCLC). Clinical trials using bortezomib as monotherapy or in combinations, such as with taxanes, gemcitabine and platinums, and novel agents are under way, and preliminary results have demonstrated activity with bortezomib as a single agent and in combination with chemotherapy in advanced NSCLC. In addition, pharmacogenomics and biomarker analysis are being used in an attempt to identify tumor types likely to respond to treatment with bortezomib.