Citations

AbstractThe immunoglobulin free light chain (FLC) assay is an invaluable tool for following patients with oligosecretory plasma cell dyscrasia. Baseline values have also been shown to be prognostic in all plasma cell disorders tested. A looming question, however, is the role it should play in following myeloma patients with disease that is measurable using serum and urine electrophoresis. We used the data and stored samples from a mature Eastern Cooperative Oncology Group clinical trial (E9486) to assess serum levels of FLC at baseline and after 2 months of alkylator-based therapy. For serial determinations, the absolute level of involved serum FLC or the difference of the involved and uninvolved FLC is preferred over the ratio of involved to uninvolved FLC. FLC response after 2 months of therapy was superior to early M-protein measurement to predict overall response. The ideal cut-point for FLC change appears to be between 40% and 50% reduction. The correlation between serial measurements of serum FLC and urine M-protein is inadequate to abolish the serial 24-hour urine protein. Although baseline values of FLC are prognostic in newly diagnosed myeloma patients, serial measurements do not appear to have added value in patients who have M-proteins measurable by electrophoresis.

Purpose The long-term impact of thalidomide plus dexamethasone (thal/dex) as primary therapy for newly diagnosed multiple myeloma (MM) is unknown. The goal of this study was to compare thalidomide plus dexamethasone versus placebo plus dexamethasone (placebo/dex)as primary therapy for newly diagnosed MM. Patients and Methods In this double-blind, placebo-controlled trial, patients with untreated symptomatic MM were randomized to thal/dex (arm A) or to placebo plus dexamethasone (dex) (arm B). Patients in arm A received oral thalidomide 50 mg daily, escalated to 100 mg on day 15, and to 200 mg from day 1 of cycle 2 (28-day cycles). Oral dex 40 mg was administered on days 1 through 4, 9 through 12, and 17 through 20 during cycles 1 through 4 and on days 1 through 4 only from cycle 5 onwards. Patients in arm B received placebo and dex, administered as in arm A. The primary end point of the study was time to progression. This study is registered at http://ClinicalTrials.gov ( NCT00057564 ). Results A total of 470 patients were enrolled (235 randomly assigned to thal/dex and 235 to placebo/dex). The overall response rate was significantly higher with thal/dex compared with placebo/dex (63% v 46%), P < .001. Time to progression (TTP) was significantly longer with thal/dex compared with placebo/dex (median, 22.6 v 6.5 months, P < .001). Grade 4 adverse events were more frequent with thal/dex than with placebo/dex (30.3% v 22.8%). Conclusion Thal/dex results in significantly higher response rates and significantly prolongs TTP compared with dexamethasone alone in patients with newly diagnosed MM.

Although the ultimate outcome of prolonged exposure of cells to stress is often death, the early response appears to be the activation of survival pathways that are likely to give the cell an opportunity to repair low-level damage. How these stress-initiated survival pathways influence B cell lymphoma/leukemia 2 (Bcl-2) proteins, the core cell death machinery, has remained unclear; however, two papers now provide insight into stress-mediated survival mechanisms. The liver is unusually resistant to p53-mediated apoptosis. It appears that p53-mediated induction of the gene that encodes insulin-like growth factor–binding protein-1 (IGFBP1) attenuates the cell death response in hepatocytes by preventing the formation of a complex between p53 and the proapoptotic protein BAK. This is especially interesting as IGFBP1 is not a member of the Bcl-2 family, yet it inhibited BAK. In three unrelated cell lines, another regulatory interaction that influences cell survival occurs at the mitochondria. In this case, protein phosphatase 1γ (PP1γ) regulated the phosphorylation status of the Bcl-2/Bcl-X L –associated death promoter (BAD). The prefoldin family member URI is normally phosphorylated by S6 kinase 1, which liberates PP1γ from a URI-PP1γ complex. However, the withdrawal of growth factors or nutrients stabilizes this complex, which renders PP1γ inactive. The net response of this stress stimulus is an increased abundance of phosphorylated BAD, which raises the threshold required to trigger cell death. These two studies have identified new players and mechanisms that integrate stress responses and cell death.