Richardson, Paul G.

Abstract Purpose: 2-Methoxyestradiol (2ME2) is an endogenous product of estradiol metabolism with antiangiogenic and antineoplastic properties. We report on the first phase II trial of 2ME2 in multiple myeloma. Experimental Design: 2ME2 was administered orally at a dose of 1,000 mg daily. Sixty patients (31 men and 29 women) were treated. After 39 patients were accrued, the dose was increased to 800 mg twice daily for the remaining patients. Results: Thirty-one patients had relapsed or refractory multiple myeloma, and 29 had plateau phase multiple myeloma. Median age was 60 years (range, 27-84 years). Therapy was well tolerated. Common adverse events included anemia (35%), fatigue (35%), nausea (25%), diarrhea (20%), hot flushes (20%), headache (17%), muscle cramps (15%), and upper respiratory tract infection (15%). Most adverse events were mild (grade 1-2); 12% experienced grade 3-4 adverse events. Median time to progression was 3.8 months, with 5.6 months for plateau phase disease and 2.3 months for relapsed multiple myeloma. Estimated progression-free survival rates for all patients at 1, 2, and 3 years were 24%, 17%, and 11%, respectively. Three patients, all with plateau phase disease, have been on study for over 4 years without progression at 50, 60, and 63 months, respectively. Minor response was noted in 2 patients. Conclusions: Although no partial responses have been seen thus far, the minor responses and prolonged stable disease seen with 2ME2 therapy are promising. Plasma levels indicate that the dose of 2ME2 was inadequate. A new formulation with better bioavailability will be tested soon in multiple myeloma.

Abstract Initial analysis of the Assessment of Proteasome Inhibition for Extending Remissions (APEX) trial of relapsed multiple myeloma patients showed significantly longer time to progression, higher response rate, and improved survival with single-agent bortezomib versus high-dose dexamethasone. In this updated analysis (median follow-up: 22 months), survival was assessed in both arms, and efficacy updated for the bortezomib arm. Median survival was 29.8 months for bortezomib versus 23.7 months for dexamethasone, a 6-month benefit, despite substantial crossover from dexamethasone to bortezomib. Overall and complete response rates with bortezomib were 43% and 9%, respectively; among responding patients, 56% improved response with longer therapy beyond initial response, leading to continued improvement in overall quality of response. Higher response quality (100% M-protein reduction) was associated with longer response duration; response duration was not associated with time to response. These data confirm the activity of bortezomib and support extended treatment in relapsed multiple myeloma patients tolerating therapy. This study is registered at http://clinicaltrials.gov (Study ID NCT00048230).

Abstract The aims of this study were to assess the feasibility of prospective pharmacogenomics research in multicenter international clinical trials of bortezomib in multiple myeloma and to develop predictive classifiers of response and survival with bortezomib. Patients with relapsed myeloma enrolled in phase 2 and phase 3 clinical trials of bortezomib and consented to genomic analyses of pretreatment tumor samples. Bone marrow aspirates were subject to a negative-selection procedure to enrich for tumor cells, and these samples were used for gene expression profiling using DNA microarrays. Data quality and correlations with trial outcomes were assessed by multiple groups. Gene expression in this dataset was consistent with data published from a single-center study of newly diagnosed multiple myeloma. Response and survival classifiers were developed and shown to be significantly associated with outcome via testing on independent data. The survival classifier improved on the risk stratification provided by the International Staging System. Predictive models and biologic correlates of response show some specificity for bortezomib rather than dexamethasone. Informative gene expression data and genomic classifiers that predict clinical outcome can be derived from prospective clinical trials of new anticancer agents.

Abstract This multicenter, open-label, randomized phase 2 study evaluated 2 dose regimens of lenalidomide for relapsed, refractory myeloma. Seventy patients were randomized to receive either 30 mg once-daily or 15 mg twice-daily oral lenalidomide for 21 days of every 28-day cycle. Patients with progressive or stable disease after 2 cycles received dexamethasone. Analysis of the first 70 patients showed increased grade 3/4 myelo-suppression in patients receiving 15 mg twice daily (41% versus 13%, P = .03). An additional 32 patients received 30 mg once daily. Responses were evaluated according to European Group for Blood and Marrow Transplantation (EBMT) criteria. Overall response rate (complete, partial, or minor) to lenalidomide alone was 25% (24% for once-daily and 29% for twice-daily lenalidomide). Median overall survival in 30-mg once-daily and twice-daily groups was 28 and 27 months, respectively. Median progression-free survival was 7.7 months on once-daily versus 3.9 months on twice-daily lenalidomide (P = .2). Dexamethasone was added in 68 patients and 29% responded. Time to first occurrence of clinically significant grade 3/4 myelosuppression was shorter in the twice-daily group (1.8 vs 5.5 months, P = .05). Significant peripheral neuropathy and deep vein thrombosis each occurred in only 3%. Lenalidomide is active and well tolerated in relapsed, refractory myeloma, with the 30-mg once-daily regimen providing the basis for future studies as monotherapy and with dexamethasone.

AbstractBone marrow angiogenesis plays an important role in the pathogenesis and progression in multiple myeloma. Recent studies have shown that proteasome inhibitor bortezomib (Velcade, formerly PS-341) can overcome conventional drug resistance in vitro and in vivo; however, its antiangiogenic activity in the bone marrow milieu has not yet been defined.In the present study, we examined the effects of bortezomib on the angiogenic phenotype of multiple myeloma patient–derived endothelial cells (MMEC). At clinically achievable concentrations, bortezomib inhibited the proliferation of MMECs and human umbilical vein endothelial cells in a dose-dependent and time-dependent manner. In functional assays of angiogenesis, including chemotaxis, adhesion to fibronectin, capillary formation on Matrigel, and chick embryo chorioallantoic membrane assay, bortezomib induced a dose-dependent inhibition of angiogenesis. Importantly, binding of MM.1S cells to MMECs triggered multiple myeloma cell proliferation, which was also abrogated by bortezomib in a dose-dependent fashion. Bortezomib triggered a dose-dependent inhibition of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) secretion by the MMECs, and reverse transcriptase-PCR confirmed drug-related down-regulation of VEGF, IL-6, insulin-like growth factor-I, Angiopoietin 1 (Ang1), and Ang2 transcription. These data, therefore, delineate the mechanisms of the antiangiogenic effects of bortezomib on multiple myeloma cells in the bone marrow milieu. (Cancer Res 2006; 66(1): 184-91)

Abstract Bortezomib, a potent and reversible proteasome inhibitor, affects the myeloma cell and its microenvironment, resulting in down-regulation of growth and survival signaling pathways and durable responses in patients with relapsed and refractory myeloma. Potential associations between baseline parameters and outcomes with bortezomib were explored in 202 patients who received bortezomib 1.3 mg/m2 twice weekly for 2 weeks every 3 weeks for up to 8 cycles in a phase 2 trial. Using European Group for Blood and Marrow Transplantation criteria, the response rate (complete or partial response) to bortezomib alone was 27% and was not associated with sex, race, performance status, isotype, chromosome 13 deletion, number or type of previous therapies, or concentration of hemoglobin or β2-microglobulin. By multivariate analysis, factors associated with lower response were being age 65 or older versus younger than 65 (19% vs 32%; P < .05) and plasma-cell infiltration in bone marrow greater than 50% versus 50% or less (20% vs 35%; P < .05). Factors that may be indicative of tumor burden (bone marrow plasma-cell infiltration greater than 50%, hypoalbuminemia, thrombocytopenia) were predictive of overall survival. Chromosome 13 deletion and elevated β2-microglobulin, generally considered poor prognostic factors, were not predictive of poor outcome with bortezomib in this study.

The 26S proteasome is a large intracellular adenosine 5′-triphosphate–dependent protease that identifies and degrades proteins tagged for destruction by the ubiquitin system. The orderly degradation of cellular proteins is critical for normal cell cycling and function, and inhibition of the proteasome pathway results in cell-cycle arrest and apoptosis. Dysregulation of this enzymatic system may also play a role in tumor progression, drug resistance, and altered immune surveillance, making the proteasome an appropriate and novel therapeutic target in cancer. Bortezomib (formerly known as PS-341) is the first proteasome inhibitor to enter clinical practice. It is a boronic aid dipeptide that binds directly with and inhibits the enzymatic complex. Bortezomib has recently shown significant preclinical and clinical activity in several cancers, confirming the therapeutic value of proteasome inhibition in human malignancy. It was approved in 2003 for the treatment of advanced multiple myeloma (MM), with approximately one third of patients with relapsed and refractory MM showing significant clinical benefit in a large clinical trial. Its mechanism of action is partly mediated through nuclear factor-kappa B inhibition, resulting in apoptosis, decreased angiogenic cytokine expression, and inhibition of tumor cell adhesion to stroma. Additional mechanisms include c-Jun N-terminal kinase activation and effects on growth factor expression. Several clinical trials are currently ongoing in MM as well as several other malignancies. This article discusses proteasome inhibition as a novel therapeutic target in cancer and focuses on the development, mechanism of action, and current clinical experience with bortezomib.

AbstractPrevious studies have demonstrated the in vitro and in vivo activity of CC-5013 (Revlimid), an immunomodulatory analog (IMiD) of thalidomide, in multiple myeloma (MM). In the present study, we have examined the anti-MM activity of rapamycin (Rapamune), a specific mTOR inhibitor, combined with CC-5013. Based on the Chou-Talalay method, combination indices of less than 1 were obtained for all dose ranges of CC-5013 when combined with rapamycin, suggesting strong synergism. Importantly, this combination was able to overcome drug resistance when tested against MM cell lines resistant to conventional chemotherapy. Moreover, the combination, but not rapamycin alone, was able to overcome the growth advantage conferred on MM cells by interleukin-6 (IL-6), insulin-like growth factor-1 (IGF-1), or adherence to bone marrow stromal cells (BMSCs). Combining rapamycin and CC-5013 induced apoptosis of MM cells. Differential signaling cascades, including the mitogen-activated protein kinase (MAPK) and the phosphatidylinositol 3′-kinase/Akt kinase (PI3K/Akt) pathways, were targeted by these drugs individually and in combination, suggesting the molecular mechanism by which they interfere with MM growth and survival. These studies, therefore, provide the framework for clinical evaluation of mTOR inhibitors combined with IMiDs to improve patient outcome in MM.