Serial virus filtration: A case study evaluating the product-dependent impact of control strategies on process efficiency.

The production of biopharmaceutical products carries an inherent risk of contamination by adventitious viruses. Historically, these manufacturing processes have incorporated a dedicated virus filtration step to ensure product safety. However, challenging process conditions can lead to passage of small viruses to the permeate pool and an overall decrease in the desired virus logarithmic reduction value (LRV) for the process. The implementation of serial virus filtration has improved the robustness of such processes, albeit concerns about increased operating times and process complexity have limited its implementation. This work focused on optimizing a serial filtration process and identifying process control strategies to provide maximum efficiency while ensuring proper controls for process complexity. Constant TMP was identified as the optimal control strategy, which combined with the optimal filter ratio, resulted in a robust and faster virus filtration process. To demonstrate this hypothesis, data with two filters connected in series (1:1 filter ratio) are presented for a representative non-fouling molecule. Similarly, for a fouling product, the optimal setup was a combination of a filter connected in series to two filters operated in parallel (2:1 filter ratio). The optimized filter ratios bring cost- and time-savings benefits to the virus filtration step, thereby offering improved productivity. The results of risk and cost analyses performed as part of this study combined with the control strategy, offer companies a toolbox of strategies to accommodate products with different filterability profiles in their downstream processes. This work demonstrates that the safety advantages of performing filters in series can be achieved with minimal increases in time, cost, and risk.

Early intervention with phosphodiesterase-5 inhibitors after prostate brachytherapy improves subsequent erectile function.

OBJECTIVE: To examine the early use of phosphodiesterase-5 inhibitor (PDE-5i; sildenafil citrate) in preventing subsequent erectile dysfunction (ED) after (monotherapy) prostate brachytherapy (PB, an accepted option for Gleason 6 or low-volume Gleason 7 prostate cancer), as PB is currently being offered more frequently in younger patients, and ED can be a side-effect often within the first 12 months after treatment. PATIENTS AND METHODS: We examined a single-surgeon series of 69 patients who had been treated with PB from 2002 to 2005. All patients had a follow-up of ≥ 1 year; prospectively, and patients had baseline, 6- and 12-month assessments using the Sexual Health Inventory for Men (SHIM) and International Index of Erectile Function (IIEF)-6 scores. The 69 patients were divided into early treatment with PDE-5i (31) and not treated with PDE-5i (38), and their SHIM and IIEF-6 scores were compared at baseline, 6 and 12 months. Daily sildenafil (25-50 mg) was given immediately after PB for 12 months. Overall, for the entire group, the mean prostate-specific antigen (PSA) level was 6.8 ng/mL; 78% had Gleason 6 cancer and 20% had Gleason 7 (3 + 4) cancer. The mean age in the early PDE-5i group was 64.8 years, and was 66.0 years in the no-PDE-5i group. The mean radiation dose in the early PDE-5i group was 50.2 Gy, and 43.9 Gy in the other group (P= 0.08). RESULTS: In the no-PDE-5i group, the mean baseline SHIM score of 17.1 decreased rapidly to 9.1 at 6 months (P= 0.01) and stayed at 9.3 at 12 months (P= 0.01). In the early PDE-5i group, the mean baseline SHIM score of 21.8 decreased slightly to 17.6 at 6 months (P= 0.2), and was maintained at 17.9 at 12 months (P= 0.2). Using the Wilcoxon rank-sum test, the 6- and 12-month SHIM scores in the two groups (P < 0.001). The IIEF-6 questionnaire confirmed the SHIM analysis. CONCLUSIONS: After PB patients had a significant decline in SHIM/IIEF-6 scores at 6 and 12 months. Our results indicate a 50% decrease in the quality of their erections. This provides an opportunity to initiate early intervention with PDE-5i or perhaps vacuum constriction devices or intraurethral alprostadil. In this study, the early use of PDE-5i after PB maintained erectile function at both 6 and 12 months.

Notch-1 regulates transcription of the epidermal growth factor receptor through p53.

The Notch pathway plays a key role in the development and is increasingly recognized for its importance in cancer. We demonstrated previously the overexpression of Notch-1 and its ligands in gliomas and showed that their knockdown inhibits glioma cell proliferation and survival. To elucidate the mechanisms downstream of Notch-1 in glioma cells, we performed microarray profiling of glioma cells transfected with Notch-1 small interfering RNA. Notable among downregulated transcripts was the epidermal growth factor receptor (EGFR), known to be overexpressed or amplified in gliomas and prominent in other cancers as well. Further studies confirmed that Notch-1 inhibition decreased EGFR messenger RNA (mRNA) and EGFR protein in glioma and other cell lines. Transfection with Notch-1 increased EGFR expression. Additionally, we found a significant correlation in levels of EGFR and Notch-1 mRNA in primary high-grade human gliomas. Subsequent experiments showed that p53, an activator of the EGFR promoter, is regulated by Notch-1. Experiments with p53-positive and -null cell lines confirmed that p53 partially mediates the effects of Notch-1 on EGFR expression. These results show for the first time that Notch-1 upregulates EGFR expression and also demonstrate Notch-1 regulation of p53 in gliomas. These observations have significant implications for understanding the mechanisms of Notch in cancer and development.

Expression of Notch-1 and its ligands, Delta-like-1 and Jagged-1, is critical for glioma cell survival and proliferation.

The Notch family of proteins plays an integral role in determining cell fates, such as proliferation, differentiation, and apoptosis. We show that Notch-1 and its ligands, Delta-like-1 and Jagged-1, are overexpressed in many glioma cell lines and primary human gliomas. Immunohistochemistry of a primary human glioma tissue array shows the presence in the nucleus of the Notch-1 intracellular domain, indicating Notch-1 activation in situ. Down-regulation of Notch-1, Delta-like-1, or Jagged-1 by RNA interference induces apoptosis and inhibits proliferation in multiple glioma cell lines. In addition, pretreatment of glioma cells with Notch-1 or Delta-like-1 small interfering RNA significantly prolongs survival in a murine orthotopic brain tumor model. These results show, for the first time, the dependence of cancer cells on a single Notch ligand; they also suggest a potential Notch juxtacrine/autocrine loop in gliomas. Notch-1 and its ligands may present novel therapeutic targets in the treatment of glioma.

Comparison of the Pharmacokinetics of Ketorolac Tromethamine After Continuous Subcutaneous Infusion and Repeat Intramuscular Bolus Injections in Healthy Adult Subjects.

Ketorolac tromethamine is a nonsteroidal anti-inflammatory drug that exhibits analgesic activity with no sedative or anxiolytic properties. Twelve healthy male subjects were enrolled in a study to receive either of 2 treatments over 2 periods in an open-label, randomized, 2-way crossover design: (A) 120 mg of ketorolac tromethamine administered as a continuous subcutaneous infusion over a 24-hour period; or (B) an identical total daily dose administered as 4 intramuscular bolus injections of 30 mg each given every 6 hours (current labeled treatment regimen). The pharmacokinetic and safety profiles were evaluated for both treatments. Both modes of administration have similar values for area under the curve (AUC) and half-life (t1/2 ), suggesting that continuous subcutaneous infusion and repeated intramuscular bolus injections have similar bioavailability. The peak plasma concentration (Cmax ) was 40% lower when ketorolac was administered as a continuous subcutaneous infusion compared with repeat intramuscular bolus injections. The concentration at steady-state (Css ) for continuous subcutaneous infusion was between the Cmax and Ctrough values obtained following the 4 intramuscular injections. Both treatment arms were well tolerated.

Clearance of prions during plasma protein manufacture.

Protein products isolated from human plasma are an important class of therapeutics that are used to treat patients afflicted with hereditary deficiencies, trauma, and severe infections. Because of the human origin of the starting material for the production of these biological products, there is a risk of transmitting infectious agents, including viruses and the infectious agents that cause transmissible spongiform encephalopathies (TSEs). The agent that is thought to cause TSEs is a disease-associated, misfolded form of the prion protein or PrP(Sc). Unlike viruses, there are no donor screening tests for TSEs available, and PrP(Sc) is resistant to traditional viral inactivation methods. Therefore, manufacturers of plasma products are faced with special challenges to ensure product safety with respect to TSEs. Fortunately, a growing body of evidence supports the capacity of manufacturing processes to remove infectious prions from the product stream during the purification of plasma products. This can be attributed in part to the unusual physicochemical nature of PrP(Sc), which is distinct from that of soluble therapeutic proteins. Although there is no reported TSE transmission through the use of plasma products to date, many unknowns remain to be addressed through long-term epidemiologic monitoring and further experimental studies.

Contribution of the MUC1 tandem repeat and cytoplasmic tail to invasive and metastatic properties of a pancreatic cancer cell line.

MUC1 is a polymorphic, highly glycosylated, type I transmembrane protein expressed by ductal epithelial cells of many organs including pancreas, breast, gastrointestinal tract, and airway. MUC1 is overexpressed and differentially glycosylated by adenocarcinomas that arise in these organs, and is believed to contribute to invasive and metastatic potential by contributing to cell surface adhesion properties [via the tandem repeat (TR) domain] and through morphogenetic signal transduction [via the cytoplasmic tail (CT)]. The large extracellular TR of MUC1 consists of a heavily glycosylated, 20 amino acid sequence that shows allelic variation with respect to number of repeats. This portion of MUC1 may directly mediate adhesive or antiadhesive interactions with other surface molecules on adjacent cells and through these interactions initiate signal transduction pathways that are transmitted through the CT. We investigated the contribution of the TR domain and the CT of MUC1 to the in vivo invasive and metastatic potential, and the gene expression profile of the human pancreatic tumor cell line S2-013. Results showed that S2-013 cells overexpressing full-length MUC1 displayed a less invasive and metastatic phenotype compared with control-transfected cells and cells expressing MUC1 lacking the TR domain or CT. Clonal populations were analyzed by cDNA array gene expression analysis, which showed differences in the gene expression profiles between the different cell lines. Among the genes differentially expressed were several that encode proteins believed to play a role in invasion and metastasis.

RNA-binding proteins to assess gene expression states of co-cultivated cells in response to tumor cells.

BACKGROUND: Tumors and complex tissues consist of mixtures of communicating cells that differ significantly in their gene expression status. In order to understand how different cell types influence one another's gene expression, it will be necessary to monitor the mRNA profiles of each cell type independently and to dissect the mechanisms that regulate their gene expression outcomes. RESULTS: In order to approach these questions, we have used RNA-binding proteins such as ELAV/Hu, poly (A) binding protein (PABP) and cap-binding protein (eIF-4E) as reporters of gene expression. Here we demonstrate that the epitope-tagged RNA binding protein, PABP, expressed separately in tumor cells and endothelial cells can be used to discriminate their respective mRNA targets from mixtures of these cells without significant mRNA reassortment or exchange. Moreover, using this approach we identify a set of endothelial genes that respond to the presence of co-cultured breast tumor cells. CONCLUSION: RNA-binding proteins can be used as reporters to elucidate components of operational mRNA networks and operons involved in regulating cell-type specific gene expression in tissues and tumors.

Marginal recurrence requiring salvage radiotherapy after stereotactic body radiotherapy for spinal metastases.

INTRODUCTION: We sought to quantify and identify risk factors associated with margin recurrence (MR) requiring salvage radiotherapy after stereotactic body radiation therapy (SBRT) for spinal metastases. METHODS: We retrospectively reviewed patients with spinal metastases who were treated with single-fraction SBRT between 2006 and 2009. Gross tumor was contoured, along with either the entire associated vertebral body(ies) or the posterior elements, and included in the planning target volume. No additional margins were used. MR was defined as recurrent tumor within one vertebral level above or below the treated lesion that required salvage radiotherapy. Only patients who presented for 3-month post-SBRT follow-up were included in the analysis. Fine and Gray competing risk regression models were generated to identify variables associated with higher risks of MR. MR was plotted using cumulative incidence analysis. RESULTS: SBRT was delivered to 208 lesions in 149 patients. Median follow-up was 8.6 months, and median survival was 12.8 months. The median prescribed dose was 14 Gy (10-16 Gy). MR occurred in 26 (12.5%) treated lesions, at a median time of 7.7 months after SBRT. Patients with paraspinal disease at the time of SBRT (20.8% vs. 7.6% of patients; p = 0.02), and those treated with <16 Gy (16.3% vs. 6.3% of patients, p = 0.14) had higher rates of MR. Both variables were associated with significantly higher risk of MR on multivariate analysis. CONCLUSION: SBRT for spinal metastases results in a low overall rate of MR. The presence of paraspinal disease at the time of SBRT and a dose of <16 Gy were associated with higher risks of MR.

External beam radiotherapy followed by 90Y ibritumomab tiuxetan in relapsed or refractory bulky follicular lymphoma.

PURPOSE: We combined external beam radiotherapy (EBRT) with yttrium-90 ibritumomab tiuxetan ((90)Y-IT) in an attempt to improve therapeutic response in patients with relapsed or refractory bulky follicular lymphoma (RRBFL). METHODS AND MATERIALS: Between February 2006 and September 2007, 11 patients with RRBFL were treated with EBRT followed by (90)Y-IT. Bulky disease (BD) was defined as >5 cm. EBRT was delivered to BD as 2,400 cGy in eight fractions using computed tomography (CT)-based planning. BD was contoured as the gross tumor volume. A planning margin of 1 to 2 cm was added depending on anatomical location. After recovery of complete blood counts (CBC), (90)Y-IT was administered at a dose of 0.3 or 0.4 mCi/kg depending on platelet counts. Hematologic toxicity was monitored through weekly CBC. Response was measured by positron emission tomography/CT or CT 3-4 months after (90)Y-IT. RESULTS: Only 2 patients required prolonged breaks between EBRT and (90)Y-IT. The median time after (90)Y-IT for platelets to recover to >100,000/ml was 55 days (range, 41-128 days). Platelet counts for 1 patient, who had received 4 previous chemotherapy regimens, never reached 100,000/ml. The complete and overall responses to combined therapy as measured 3-4 months after (90)Y-IT were 64%. No patients relapsed within the EBRT field. With a median follow-up of 36.1 months, 6 patients have relapsed, 2 of whom have died. Median progression-free survival was 17.5 months. CONCLUSIONS: In contrast to prior failure analysis data for RRBFL patients treated with (90)Y-IT alone, a brief course of EBRT prevented relapse in sites of BD. EBRT used to pretreat bulky sites may improve clinical outcomes and potentially extend survival when combined with (90)Y-IT.

Maximum standardized uptake value from staging FDG-PET/CT does not predict treatment outcome for early-stage non-small-cell lung cancer treated with stereotactic body radiotherapy.

PURPOSE: To perform a retrospective review to determine whether maximum standardized uptake values (SUV(max)) from staging 2-deoxy-2- [(18)F] fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) studies are associated with outcomes for early-stage non-small-cell lung cancer (NSCLC) treated with stereotactic body radiotherapy (SBRT). METHODS AND MATERIALS: Seventy-two medically inoperable patients were treated between October 17, 2003 and August 17, 2007 with SBRT for T1-2N0M0 NSCLC. SBRT was administered as 60 Gy in 3 fractions, 50 Gy in 5 fractions, or 50 Gy in 10 fractions using abdominal compression and image-guided SBRT. Cox proportional hazards regression was performed to determine whether PET SUV(max) and other variables influenced outcomes: mediastinal failure (MF), distant metastases (DM), and overall survival (OS). RESULTS: Biopsy was feasible in 49 patients (68.1%). Forty-nine patients had T1N0 disease, and 23 had T2N0 disease. Median SUV(max) was 6.55 (range, 1.5-21). Median follow-up was 16.9 months (range, 0.1-37.9 months). There were 3 local failures, 8 MF, 19 DM, and 30 deaths. Two-year local control, MF, DM, and OS rates were 94.0%, 10.4%, 30.1%, and 61.3%, respectively. In univariate analysis, PET/CT SUV(max), defined either as a continuous or dichotomous variable, did not predict for MF, DM, or OS. On multivariable analysis, the only predictors for overall survival were T1 stage (hazard ratio = 0.331 [95% confidence interval, 0.156-0.701], p = 0.0039) and smoking pack-year history (hazard ratio = 1.015 [95% confidence interval, 1.004-1.026], p = 0.0084). CONCLUSIONS: Pretreatment PET SUV(max) did not predict for MF, DM, or OS in patients treated with SBRT for early-stage NSCLC.

Update on the rational use of tositumomab and iodine-131 tositumomab radioimmunotherapy for the treatment of non-Hodgkin's lymphoma.

Targeted radioimmunotherapy in non-Hodgkin's B-cell lymphoma (NHL) offers an efficacious therapy and minimal toxicity compared to conventional chemotherapy. Iodine 131 tositumomab ((131)I-TST) is a murine monoclonal antibody against the CD20 cell surface protein and is directly covalently conjugated to (131)I, a radioactive beta and gamma emitter. While initially approved for use in relapsed, refractory, or transformed low grade B-cell NHL, investigational uses with promising results include autologous stem cell transplant, intermediate grade NHL, and the frontline management of indolent NHL. This review summarizes the (131)I-TST literature on mechanism of action, treatment indications, treatment delivery, efficacy, investigational uses, and future prospects.

Comparison of biochemical relapse-free survival between primary Gleason score 3 and primary Gleason score 4 for biopsy Gleason score 7 prostate cancer.

PURPOSE: To determine whether the primary grade (PG) of biopsy Gleason score (GS) 7 prostate cancer (CaP) was predictive for biochemical relapse-free survival (bRFS). Most of the present data regarding the PG of GS7 CaP refer to surgical specimens. Our goal was to determine whether the biopsy GS used at the time of medical decision making predicted for the biochemical outcome. METHODS AND MATERIALS: We reviewed the data from 705 patients with biopsy GS7 CaP, from a prospectively maintained database, who had been treated at our institution between September 1996 and March 2005 with radical prostatectomy (n = 310), external beam radiotherapy (n = 268), or prostate radioactive seed implantation (n = 127). The bRFS rates were estimated using the Kaplan-Meier method. Cox proportional hazards regression analysis was used for univariate and multivariate analyses examining these factors in relation to bRFS: PG of biopsy GS, initial prostate-specific antigen level, clinical T stage, use of androgen deprivation, risk group (high or intermediate), and treatment modality. RESULTS: The 5-year bRFS rate was 78% and 71% (p = 0.0108) for biopsy GS7 PG3 CaP and biopsy GS7 PG4 CaP, respectively. Comparing PG3 and PG4 within treatment modalities, only prostate implantation patients had a significant difference in the 5-year bRFS rate, 88% vs. 76%, respectively (p = 0.0231). On multivariate analysis, the PG of biopsy GS remained an independent predictor of bRFS, with PG3 having better bRFS than PG4 (relative risk, 0.655; 95% confidence interval, 0.472-0.909; p = 0.0113). CONCLUSION: Biopsy GS7 PG4 CaP carries a worse bRFS than biopsy GS7 PG3 CaP.

A single glycosylation site within the receptor-binding domain of the avian sarcoma/leukosis virus glycoprotein is critical for receptor binding.

Retroviral envelope proteins are heavily glycosylated. In some cases, glycosylation has been shown to be important for folding, protein stability, immune evasion, or receptor usage. The receptor-binding subunit (SU or gp85) of the envelope protein (EnvA) of the avian sarcoma/leukosis virus, subtype A (ASLV-A), contains 11 potential N-linked glycosylation sites (NXS/T). To address the importance of N-linked glycosylation for the function of EnvA, we prepared a series of EnvA proteins lacking one or more of these carbohydrate addition sites. Using site-directed mutagenesis, we mutated the S or T in each NXS/T glycosylation sequon to A. We also prepared EnvAs bearing selected double and triple mutations. We examined each mutant EnvA for its ability to be expressed at the cell surface, proteolytically processed into gp85 and gp37, incorporated into MLV pseudotyped virions, and to support infection of cells expressing the ASLV-A receptor, Tva. Eight single mutations were well tolerated, and, in general, EnvA was able to tolerate double mutations of these glycosylation sites. Triple mutations were more variable in their effects. Of the three glycosylation sites important for EnvA function, two are important for folding (EnvA production and processing were severely impaired). For the third, although EnvA processing was impaired, significant amounts of processed EnvA were expressed at the cell surface and incorporated into virions. Nonetheless, this mutant EnvA, EnvADeltaNg10, was unable to support infection. Further examination of EnvADeltaNg10 revealed that it was unable to bind Tva and was severely impaired for binding to a monoclonal antibody which inhibits receptor binding. This work has therefore identified a single N-linked glycosylation site in the SU domain of EnvA that is critical for binding between EnvA and its receptor, Tva.