Citations

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.

Purpose Patients with newly diagnosed, advanced-stage, follicular grade 1 non-Hodgkin's lymphoma (NHL) are often asymptomatic and can be observed without immediate chemotherapy. The goals of this study were to assess the overall response rate (ORR) to rituximab in this patient population and to determine the time-to-progression (TTP) and time-to-subsequent-chemotherapy (TTSC). Patients and Methods Eligible patients had untreated follicular grade 1 NHL, and measurable stage III/IV disease. Patients received rituximab 375 mg/m2 intravenous weekly × 4 doses and were then followed for response and progression; no maintenance therapy was provided. Results Thirty-seven patients were accrued; one patient was ineligible. The median age was 59 years (range, 29 to 83 years). Six patients (18%) had elevated lactate dehydrogenase levels. The ORR was 72%, with 36% complete remissions. Fourteen (39%) of 36 patients remain in unmaintained remission, two died without disease progression, and three died with disease progression. Twenty (56%) of 36 patients have disease progression. The median TTP was 2.2 years (95% CI, 1.3 to not yet reached). Eighteen patients have subsequently been treated with chemotherapy, with a median TTSC of 2.3 years (95% CI, 1.6 to not yet reached). Patients with a high lactate dehydrogenase level had a lower ORR of 33% and a short TTP of only 6 months. Conclusion Rituximab can be safely administered to patients with advanced-stage follicular grade 1 NHL with efficacy and minimal toxicity. This therapy is highly active and offers an acceptable alternative to observation in this patient population. Patients with high LDH should not be considered for rituximab monotherapy.

Background— Observed rates of restenosis after drug-eluting stenting are low (<10%). Identification of a reliable and powerful angiographic end point will be useful in future trials. Methods and Results— Late loss (postprocedural minimum lumen diameter minus 8-month minimum lumen diameter) was measured in the angiographic cohorts of the SIRIUS (n=703) and E-SIRIUS (n=308) trials. Two techniques, the standard normal approximation and an optimized power transformation, were used to predict binary angiographic restenosis rates and compare them with observed restenosis rates. The mean in-stent late loss observed in the SIRIUS trial was 0.17±0.45 mm (sirolimus) versus 1.00±0.70 mm (control). If a normal distribution was assumed, late loss accurately estimated in-stent binary angiographic restenosis for the control arm (predicted 35.4% versus observed 35.4%) but underestimated it in the sirolimus arm (predicted 0.6% versus observed 3.2%). Power transformation improved the reliability of the estimate in the sirolimus arm (predicted 3.2% [CI 1.0% to 6.7%]) with similar improvements in the E-SIRIUS trial (predicted 4.0% [CI 1.2% to 7.0%] versus observed 3.9%). In the sirolimus-eluting stent arm, in-stent late loss correlated better with target-lesion revascularization than in-segment late loss (c-statistic=0.915 versus 0.665). Conclusions— Because distributions of late loss with a low mean are right-skewed, the use of a transformation improves the accuracy of predicting low binary restenosis rates. Late loss is monotonically correlated with the probability of restenosis and yields a more efficient estimate of the restenosis process in the era of lower binary restenosis rates.

Background— In case series, mitral regurgitation (MR) increased the risk of death after myocardial infarction (MI), yet the prevalence of MR, its incremental prognostic value over ejection fraction (EF), and its association with heart failure and death after MI in the community is not known. Methods and Results— The prevalence of MR and its association with heart failure and death were examined among 1331 patients within a geographically defined MI incidence cohort between 1988 and 1998. Echocardiography was performed within 30 days after MI in 773 patients (58%), and MR was present in 50% of cases, mild in 38%, and moderate or severe in 12%. Among patients with MR, a murmur was inconsistently detected clinically. After 4.7±3.3 years of follow-up, 109 episodes of heart failure and 335 deaths occurred. There was a graded positive association between the presence and severity of MR and heart failure or death. Moderate or severe MR was associated with a large increase in the risk of heart failure (relative risk 3.44, 95% CI 1.74 to 6.82, P <0.001) and death (relative risk 1.55, 95% CI 1.08 to 2.22, P =0.019) among 30-day survivors independent of age, gender, EF, and Killip class. Conclusions— In the community, MR is frequent and often silent after MI. It carries information to predict heart failure or death among 30-day survivors independently of age, gender, EF, and Killip class. These findings, which are applicable to a large community-based MI cohort, suggest that the assessment of MR should be included in post-MI risk stratification.

We have prospectively studied the outcome of infections associated with implants which were retained and treated using a standardised antimicrobial protocol. Over a period of four years, we studied 24 consecutive patients who had symptoms of infection for less than one year, a stable implant, no sinus tract and a known pathogen which was susceptible to recommended antimicrobial agents. The infections involved hip prostheses (14), knee prostheses (5), an internal fixation device (4), and an ankle prosthesis (1). Twenty patients had a successful outcome at a median follow-up of 3.7 years (1.8 to 4.7); four had failure of the implant after a median follow-up of 1.2 years (0.3 to 2.5). The probability of survival without failure of treatment was 96% at one year (95% confidence interval (CI) 88 to 100), 92% at two years (95% CI 80 to 100) and 86% at three years (95% CI 72 to 100). Patients with a short-term infection but with a stable implant, no sinus tract and a known pathogen may be successfully treated by retention of the implant and the use of a standardised regimen of antimicrobial treatment.

Abstract Mantle-cell lymphoma (MCL) is a unique subtype of B-cell non-Hodgkin lymphoma (NHL) that behaves aggressively and remains incurable. In order to understand the pathogenesis of MCL and design new therapies, it is important to accurately analyze molecular changes in pathways dysregulated in MCL. We used antibody microarrays to compare patterns of protein expression between CD19+ purified B lymphocytes from normal tonsil and 7 cases of histologically confirmed MCL. Protein overexpression was defined as a higher than 1.3-fold or 2-fold increase in at least 67% of tumor samples compared with normal B-cell control. Of the polypeptides, 77 were overexpressed using the higher than 1.3-fold cutoff, and 13 were overexpressed using the 2-fold cutoff. These included cell cycle regulators (regulator of chromosome condensation 1 [RCC1], murine double minute 2 [MDM2]), a kinase (citron Rho-interacting kinase [CRIK]), chaperone proteins (heat shock 90-kDa protein [Hsp90], Hsp10), and phosphatase regulators (A-kinase anchor protein 1 [AKAP149], protein phosphatase 5 [PP5], and inhibitor 2). The elevated expression of some of these polypeptides was confirmed by immunoblotting and immunohistochemistry, whereas elevated expression of others could not be confirmed, illustrating the importance of confirmatory studies. This study describes a novel technique that identifies proteins dysregulated in MCL.