Stabilization of adalimumab Fab through the introduction of disulfide bonds between the variable and constant domains.

Fab is a promising format for antibody drug. Therefore, efforts have been made to improve its thermal stability for therapeutic and commercial use. So far, we have attempted to introduce a disulfide bond into the Fab fragment to improve its thermal stability and demonstrated that it is possible to do this without sacrificing its biochemical function. In this study, to develop a novel stabilization strategy for Fab, we attempted to introduce a disulfide bond between the variable and constant domains and prepared three variants of Fab; H:G10C + H:P210C, L:P40C + L:E165C, and H:G10C + H:P210C + L:P40C + L:E165C. Differential scanning calorimetry measurements showed that each of these variants had improved thermal stability. In addition, the variants with two disulfide bonds demonstrated a 6.5 °C increase in their denaturation temperatures compared to wild-type Fab. The introduction of disulfide bonds was confirmed by X-ray crystallography, and the variants retained their antigen-binding activity. The variants were also found to be less aggregative than the wild type. Our results demonstrate that the introduction of a disulfide bond between the variable and constant domains significantly improves the thermal stability of Fab.

Bovine ultralong CDR-H3 derived knob paratopes elicit potent TNF-α neutralization and enable the generation of novel adalimumab-based antibody architectures with augmented features.

In this work we have generated cattle-derived chimeric ultralong CDR-H3 antibodies targeting tumor necrosis factor α (TNF-α) via immunization and yeast surface display. We identified one particular ultralong CDR-H3 paratope that potently neutralized TNF-α. Interestingly, grafting of the knob architecture onto a peripheral loop of the CH3 domain of the Fc part of an IgG1 resulted in the generation of a TNF-α neutralizing Fc (Fcknob) that did not show any potency loss compared with the parental chimeric IgG format. Eventually, grafting this knob onto the CH3 region of adalimumab enabled the engineering of a novel TNF-α targeting antibody architecture displaying augmented TNF-α inhibition.

Comparison of consistency and complementarity of reporting biosimilar quality attributes between regulatory and scientific communities: An adalimumab case study.

Biosimilar approval relies on the comparability of quality attributes (QAs), for which information can be derived from regulatory or scientific communities. Limited information is known about whether these sources are consistent with or complementary to each other. The consistency and complementarity of QA reporting in biosimilarity assessments for adalimumab biosimilars approved by the European Medicines Agency in European public assessment reports (EPARs) and scientific publications was assessed. A classification of 77 different QAs (53 structural and 24 functional attributes) was used to assess the types of and information on QAs reported. Six adalimumab biosimilars were analyzed, for which the number of QAs reported in EPARs and publications varied (range = 47 [61%]-60 [78%]). The proportion of QAs consistently reported in both sources varied (range = 28%-75%) among biosimilars; functional QAs (mean = 21 QAs [88%]; range = 19-23) were more consistently reported than structural QAs (mean = 33 QAs [62%]; range = 27-34). The EPARs frequently reported biosimilarity interpretation without providing test results (9-57 QAs in EPARs versus 0-8 QAs in publications), whereas publications frequently reported both test results and interpretations (13-40 QAs in publications versus 0-3 QAs in EPARs). Both sources provided information on the biosimilarity of QAs in a complementary manner and the same biosimilarity interpretation of test results for reported QAs (mean = 90%; range = 78%-100%), with a small discrepancy in biosimilarity interpretations of a few clinically relevant QAs related to post-translation modifications and biological activity. Comprehensive reporting of QAs can contribute to an improved understanding of the role of structural and functional attributes in establishing biosimilarity and the mechanism of action of biological substances in general.

New insights on the interaction mechanism of rhTNFα with its antagonists Adalimumab and Etanercept.

TNFα is a pro-inflammatory cytokine that is a therapeutic target for inflammatory autoimmune disorders. Thus, TNFα antagonists are successfully used for the treatment of these disorders. Here, new association patterns of rhTNFα and its antagonists Adalimumab and Etanercept are disclosed. Active rhTNFα was purified by IMAC from the soluble fraction of transformed Escherichia coli. Protein detection was assessed by SDS-PAGE and Western blot. The KD values for rhTNFα interactions with their antagonists were obtained by non-competitive ELISA and by microscale thermophoresis (MST). Molecular sizes of the complexes were evaluated by size-exclusion chromatography-high performance liquid chromatography (SEC-HPLC). Surprisingly, both antagonists recognized the monomeric form of rhTNFα under reducing and non-reducing conditions, indicating unexpected bindings of the antagonists to linear epitopes and to rhTNFα monomers. For the first time, the interactions of rhTNFα with Adalimumab and Etanercept were assessed by MST, which allows evaluating molecular interactions in solution with a wide range of concentrations. Biphasic binding curves with low and high KD values (<10-9 M and >10-8 M) were observed during thermophoresis experiments, suggesting the generation of complexes with different stoichiometry, which were confirmed by SEC-HPLC. Our results demonstrated the binding of TNFα-antagonists with rhTNFα monomers and linear epitopes. Also, complexes of high molecular mass were observed. This pioneer investigation constitutes valuable data for future approaches into the study of the interaction mechanism of TNFα and its antagonists.

Identification and Quantification of Oxidation Products in Full-Length Biotherapeutic Antibodies by NMR Spectroscopy.

Therapeutic proteins are an indispensable class of drugs and often therapeutics of last resort. They are sensitive to oxidation, which is of critical concern, because it can affect drug safety and efficacy. Protein oxidation, with methionine and tryptophan as the most susceptible moieties, is mainly monitored by HPLC-MS techniques. However, since several oxidation products display the same mass difference, their identification by MS is often ambiguous. Therefore, an alternative analytical method able to unambiguously identify and, ideally, also quantify oxidation species in proteins is highly desired. Here, we present an NMR-based approach to monitor oxidation in full-length proteins under denaturing conditions, as demonstrated on two biotherapeutic monoclonal antibodies (mAbs). We show that methionine sulfoxide, methionine sulfone, N-formylkynurenine, kynurenine, oxindolylalanine, hydroxypyrroloindole, and 5-hydroxytryptophan result in characteristic chemical shift correlations suited for their identification and quantification. We identified the five most abundant oxidation products in forced degradation studies of two full-length therapeutic mAbs and can also unambiguously distinguish oxindolylalanine from 5-hydroxytryptophan, which are undistinguishable by MS due to the same mass shift. Quantification of the abundant methionine sulfoxide by NMR and MS gave highly comparable values. These results underline the suitability of NMR spectroscopy for the identification and quantification of critical quality attributes of biotherapeutics.

Middle Level IM-MS and CIU Experiments for Improved Therapeutic Immunoglobulin Subclass Fingerprinting.

Most of the current FDA and EMA approved therapeutic monoclonal antibodies (mAbs) are based on humanized or human IgG1, 2, or 4 subclasses and engineered variants. On the structural side, these subclasses are characterized by specific interchain disulfide bridge connections. Different analytical techniques have been reported to assess intact IgGs subclasses, with recently special interest in native ion mobility (IM) and collision induced unfolding (CIU) mass spectrometry (MS). However, these two techniques exhibit significant limitations to differentiate mAb subclasses at the intact level. In the present work, we aimed at developing a unique IM-MS-based approach for the characterization of mAb subclasses at the middle level. Upon IdeS-digestion, the unfolding patterns of the F(ab')2 and Fc domains were simultaneously analyzed in a single run to provide deeper structural insights of the mAb scaffold. The unfolding patterns associated with the F(ab')2 domains are completely different in terms of unfolding energies and number of transitions. Thereby, F(ab')2 regions are the diagnostic domain to provide specific unfolding signatures to differentiate IgG subclasses and provide more confident subclass categorization than CIU on intact mAbs. In addition, the potential of middle-level CIU was evaluated through the characterization of eculizumab, a hybrid therapeutic IgG2/4 mAb. The unfolding signatures of both domains were allowed to corroborate, within a single run, the hybrid nature of eculizumab as well as specific subclass domain assignments to the F(ab')2 and Fc regions. Altogether, our results confirm the suitability of middle-level CIU of F(ab')2 domains for subclass categorization of canonical and more complex new generation engineered antibodies and related products.

Intact and middle-down CIEF of commercial therapeutic monoclonal antibody products under non-denaturing conditions.

A two-step CIEF with chemical mobilization was developed for charge profiling of the therapeutic mAb rituximab under non-denaturing separation conditions. CIEF of the intact mAb was combined with a middle-down approach analyzing Fc/2 and F(ab´)2 fragments after digest with a commercial cysteine protease (IdeS). CIEF methods were optimized separately for the intact mAb and its fragments due to their divergent pIs. Best resolution was achieved by combining Pharmalyte (PL) 8-10.5 with PL 3-10 for variants of intact rituximab and of F(ab´)2 fragments, respectively, whereas PL 6.7-7.7 in combination with PL 3-10 was used for Fc/2 variants. Charge heterogeneity in Fc/2 dominates over F(ab´)2 . In addition, a copy product of rituximab, and adalimumab were analyzed. Both mAbs contain additional alkaline C-terminal lysine variants as confirmed by digest with carboxypeptidase B. The optimized CIEF methods for intact mAb and Fc/2 were tested for their potential as platform approaches for these mAbs. The CIEF method for Fc/2 was slightly adapted in this process. The pI values for major intact mAb variants were determined by adjacent pI markers resulting in 9.29 (rituximab) and 8.42 (adalimumab). In total, seven to eight charge variants could be distinguished for intact adalimumab and rituximab, respectively.

Assessment of Antibody Self-Interaction by Bio-Layer-Interferometry as a Tool for Early Stage Formulation Development.

PURPOSE: To speed up the drug development process in the biopharmaceutical industry, high throughput methods are indispensable for assessing drug candidates and potential lead formulations, in particular during late stages of discovery and early phases of development. This study aimed to establish a bio-layer-interferometry based high throughput assay for assessing formulation dependent mAb self-interaction (SI-BLI) and to compare the results with kD values obtained by dynamic light scattering (DLS). METHODS: Self-interaction of proprietary and commercially available mAbs was analyzed by SI-BLI and dynamic light scattering (DLS). RESULTS: We found significant correlations of the SI-BLI results and kD-values obtained by DLS for both, different mAbs in one platform formulation and for mAbs formulated in several buffer compositions. In total, we assessed self-interaction propensity of different mAbs in 58 formulations and found significant Pearson correlation (p < 0.05) between kD and results of SI-BLI. CONCLUSIONS: The SI-BLI results correlate with kD and enable fast ranking of both different drug candidates and potential lead formulations. Thus, SI-BLI might decrease the risk to lose potent mAb candidates during transition from discovery to development, and help to accelerate the development of high concentration liquid formulations.

C-Terminal Cysteine PEGylation of Adalimumab Fab with an Engineered Interchain SS Bond.

Conjugation with polyethylene glycol (PEG) is performed to increase serum half-life of the Fab for clinical applications. However, current designs for recombinant Fab only allow PEGylation at the interchain SS bond (disulfide bond) at the C-terminal end of the heavy chain and light chain of the Fab, which the decrease of thermostability occurred by partial reduction of the interchain SS bond. An adalimumab Fab mutant with a novel interchain SS bond (CH1 : C177-CL : C160) and one cysteine at the C-terminal end (mutSS FabSH) was designed to maintain Fab thermostability and for site-specific PEGylation. MutSS FabSH was expressed in Pichia pastoris and purified mutSS FabSH was conjugated with 20-kDa PEG targeted at the free cysteine. Based on enzyme-linked immunosorbent assay (ELISA), PEGylation did not affect the binding capacity of the mutSS FabSH. To confirm the influence of PEGylation on the pharmacokinetic behavior of the Fab, PEGylated mutSS FabSH was administered to rats via tail vein injection. Analysis of the mean serum concentration of the PEGylated mutSS FabSH versus time through ELISA indicated an increase in half-life compared to that of non-PEGylated wild-type Fab. Consequently, we have successfully demonstrated that a Fab mutant with a novel interchain SS bond and one free cysteine at the C-terminal end can be PEGylated without changes in functionality. This design can potentially be used as a platform for modification of other recombinant Fabs.

Development of anti-drug monoclonal antibody panels against adalimumab and infliximab.

The generation of anti-drug antibodies (ADAs) is one of the most serious problems in therapy using monoclonal antibodies (mAbs), because ADAs can impact the pharmacokinetics, efficacy, and safety of mAbs. It is therefore important to detect the generated ADAs in patients. For the appropriate detection of ADAs, methods that detect various types of ADAs (e.g., low- and high-affinity ADAs) are needed, but since there are no adequate reference preparations of ADAs relevant to human ADAs in most cases, it is difficult to determine whether or not the developed methods have enough analytical performance. Here, we developed human-rat chimeric ADA panels against the anti-TNF-α therapeutic antibodies infliximab and adalimumab. The developed ADA panels consist of 7 (for infliximab) and 11 (for adalimumab) ADAs with various binding characters, and most of the ADAs are neutralizing antibodies. Using these ADA panels, we compared the detectability of model methods, i.e., binding assays using SPR, BLI, and ECL, and a cell-based assay to detect neutralization activity. Since we obtained ADAs showing low and high responses with the various methods, the ADA panels we developed were shown to be useful for the development of ADA assays.

Comparative nonclinical assessments of the biosimilar PF-06410293 and originator adalimumab.

Adalimumab, a recombinant fully human monoclonal antibody targeting tumor necrosis factor (TNF), is approved in the United States and Europe to treat various inflammatory and autoimmune indications. Biosimilars are approved biologics highly similar, but not identical, to approved biotherapeutics. To support clinical development of PF-06410293, an adalimumab biosimilar, nonclinical studies evaluated the structural, functional, toxicologic, and toxicokinetic similarity to originator adalimumab sourced from the United States (adalimumab-US) and European Union (adalimumab-EU). Structural similarity was assessed by peptide mapping. Biologic activity was measured via inhibition of TNF-induced apoptosis and Fc-based functionality assessments. In vivo nonclinical similarity was evaluated in a toxicity study in cynomolgus monkeys administered subcutaneous PF-06410293 or adalimumab-EU (0 or 157 mg/kg/week). Peptide mapping demonstrated PF-06410293, adalimumab-US, and adalimumab-EU had identical amino acid sequences. Comparative functional and binding assessments were similar. Effects of PF-06410293 and adalimumab-EU were similar and limited to pharmacologically mediated decreased cellularity of lymphoid follicles and germinal centers in spleen. Toxicokinetics were similar; maximum plasma concentration and area-under-the-concentration-time curve ratio of PF-06410293:adalimumab-EU ranged from 1.0 to 1.2. These studies supported PF-06410293 entry into clinical development. Many regulatory agencies now only request nonclinical in vivo testing if there is residual uncertainty regarding biosimilarity after in vitro analytical studies.

Impact of pain associated with the subcutaneous administration of adalimumab.

BACKGROUND: There is limited information regarding the impact of patients' perception of injection pain on adherence to treatments, specifically in inflammatory bowel disease (IBD) patients. Therefore, we aimed to determine the impact of the pain associated with the subcutaneous administration of adalimumab in patients with IBD treated with the old formulation and the new low-volume/citrate-free formulation. METHODS: A specifically-designed questionnaire was completed by 76 patients with IBD, who started treatment with adalimumab before the availability of the low-volume/citrate-free formulation and were switched to this new formulation. Intensity of pain was measured by using visual analog scales (VAS). RESULTS: A total of 62 patients (82%) experienced injection-related pain with the initial formulation. The perception of pain was associated with a decreased adherence to the treatment (37%), an increase in pre-administration anxiety (25%) or, as a consequence, the patient required someone else to carry out the injection (21%). Younger age was the only factor associated with pain perception. After switching to the new formulation, perception of pain persisted only in 2 patients (3%). Among those who felt pain with the initial formulation, pre-administration anxiety disappeared in 44%; 32% and 42% stated that the new formulation eased adherence and self-administration. CONCLUSIONS: The perception of pain related to the subcutaneous administration of therapy negatively impacts on treatment adherence in IBD patients. Improved formulations for subcutaneous administration of drugs can positively impact patients' convenience and adherence.

Phage display derived therapeutic antibodies have enriched aliphatic content: Insights for developability issues.

Phage display is one of the most widely used technology for antibody discovery and engineering. Number of therapeutic antibodies derived from phage display increases rapidly due to its ease of use and ability to control antibody sequence information. Although there are numerous antibody candidates as promising therapeutics, most of them fail at later stages of development due to undesired biophysical properties. Antibody candidates with poor properties should be prevented or improved in early development phases to minimize enormous loss of time and resources. In this study, we showed that phage display derived therapeutic antibodies show higher self-interaction and polyspecificity compared to non-phage display derived ones. To identify molecular determinants behind this, physicochemical properties of CDR regions of 137 therapeutic antibodies were analyzed. We found multiple significant differences in both heavy and light chain CDR regions. Most profoundly, aliphatic content of HCDR3, HCDR2, and LCDR3 regions were enriched in phage display derived antibodies compared to non-phage display derived ones. Physicochemical determinants documented here seem to play important roles in polyspecific and aggregation-prone natures of antibodies which should be avoided in early development phases.

Unambiguous Identification of Pyroglutamate in Full-Length Biopharmaceutical Monoclonal Antibodies by NMR Spectroscopy.

Biotherapeutic proteins are an indispensable class of pharmaceuticals that present a high degree of structural complexity and are prone to chemical modifications during production, processing, and storage, which have to be tightly controlled. Pyroglutamate (pGlu), a cyclization product of N-terminal Gln or Glu residues, is a widespread post-translational modification in proteins, including monoclonal antibodies (mAbs). The unambiguous identification and quantification of this modification in proteins is challenging, since the mass difference of -17 Da or -18 Da, when formed from Gln or Glu, respectively, is not unique. Moreover, deamidation and dehydration occur not only during cyclization to pGlu, but also during other reactions leading to different types of modifications, like succinimide or isopeptide bond moieties due to cross-linking between Asn or Gln and Lys side chains. Here we report the unambiguous identification and quantification of pGlu in intact mAbs with natural isotope distribution by NMR spectroscopy. The assignment of all 1H, 13C and 15N random coil chemical shifts of pGlu in short reference peptides led to the identification of unique chemical shift pairs that are distinct from the random coil chemical shifts of the natural amino-acid residues. These characteristic correlations are suited for the detection of pGlu in denatured proteins. We achieved complete denaturation of mAbs using a straightforward protocol, and could detect and quantify pGlu, in agreement with available mass spectrometric data. The application to the mAbs rituximab and adalimumab illustrates the potential of our approach for the characterization of biotherapeutics containing isotopes at natural abundance.

Evaluation of the pattern and kinetics of degradation of adalimumab using a stability-indicating orthogonal testing protocol.

Forced degradation studies are crucial for the evaluation of the stability and biosimilarity. Here, adalimumab was subjected to oxidation, pH, temperature, agitation and repeated freeze-thaw in order to generate all possible degradation products. An orthogonal stability-indicating testing protocol comprising SE-HPLC, RP-HPLC, TapeStation gel electrophoresis, dynamic light scattering (DLS), and functional receptor binding assay was developed and validated. The assay protocol was used for the assessment of the pattern and kinetics of aggregation/degradation of adalimumab. SE-HPLC and DLS were used to show the formation of aggregates/fragments of adalimumab under nondenaturing conditions. TapeStation electrophoresis was performed under denaturing conditions to reveal the nature of aggregates. Results of the receptor binding assay agreed to those of SE-HPLC and DLS which indicated that it can be used as an activity-indicating assay for adalimumab. RP-HPLC demonstrated excellent selectivity for adalimumab in the presence of its oxidized forms. The kinetics of degradation was studied in each case and the results showed that it followed the first-order reaction kinetics. Correlation between the results supported the quality assessment of the tested product in industrial and clinical settings. This orthogonal protocol is a useful tool in stability assessment of monoclonal antibodies and a key criterion for the biosimilarity assessment.

Development and Qualification of a Scale-Down Mammalian Cell Culture Model and Application in Design Space Development by Definitive Screening Design.

Scale-down models are indispensable and crucial tools for process understanding and continuous process improvement in product life-cycle management. In this study, a scale-down model representing commercial-scale cell culture process of adalimumab biosimilar HS016 was first developed based on constant power per volume (P/V) principle and then qualified by multivariate data analysis (MVDA) and equivalence test method. The trajectories of the bench-scale process lie in the middle of the control range of large-scale process, built by multivariate evolution model based on nutrients, metabolites, and process performance datasets. This indicates that the small-scale process performance is comparable with that of the full-scale process. The final product titer, integrated viable cell density (iVCD), viability, aggregates, acid peak content, total afucosylation level, and high mannose content recognized as key process attributes (KPAs) or critical quality attributes (CQAs) were equivalent across the scales upon comparison using equivalence test method. The qualified scale-down model was then used for process characterization using a definitive screening design (DSD) where five independent variables including pH, shifted temperature, inoculation seeding density, viable cell density (VCD) at first feeding, VCD at temperature shift were evaluated. Three quadratic polynomial models for final product titer, aggregation, and high mannose were then established using the DSD results. The design space was finally developed using a probability-based Monte Carlo simulation method and was verified with the operation setpoint and worst-case condition. The case study presented in this report shows a feasible roadmap for cell culture process characterization.

A novel engineered interchain disulfide bond in the constant region enhances the thermostability of adalimumab Fab.

We constructed a system for expressing the Fab of the therapeutic human monoclonal antibody adalimumab at a yield of 20 mg/L in the methylotrophic yeast Pichia pastoris. To examine the contribution of interchain disulfide bonds to conformational stability, we prepared adalimumab Fab from which the interchain disulfide bond at the C-terminal region at both the CH1 and CL domains was deleted by substitution of Cys with Ala (FabΔSS). DSC measurements showed that the Tm values of FabΔSS were approximately 5 °C lower than those of wild-type Fab, suggesting that the interchain disulfide bond contributes to conformational thermostability. Using computer simulations, we designed a novel interchain disulfide bond outside the C-terminal region to increase the stability of FabΔSS. The resulting Fab (mutSS FabΔSS) had the mutations H:V177C and L:Q160C in FabΔSS, confirming the formation of the disulfide bond between CH1 and CL. The thermostability of mutSS FabΔSS was approximately 5 °C higher than that of FabΔSS. Therefore, the introduction of the designed interchain disulfide bond enhanced the thermostability of FabΔSS and mitigated the destabilization caused by partial reduction of the interchain disulfide bond at the C-terminal region, which occurs in site-specific modification such as PEGylation.

Introduction of a glycosylation site in the constant region decreases the aggregation of adalimumab Fab.

The production of therapeutic monoclonal antibodies is costly; therefore, antigen-binding fragments (Fabs) can be used instead. However, their tendency toward aggregation can reduce the half-life in the plasma and the therapeutic effectiveness. To examine the effect of glycosylation on the properties of the Fab of a therapeutic antibody, an N-glycosylation site was introduced at position 178 of the H-chain constant region of adalimumab Fab through site-directed mutagenesis of L178 N (H:L178 N Fab), and then H:L178 N Fab was expressed in Pichia pastoris. SDS-PAGE analysis with treatment of N-glycosidase F or periodic acid-Schiff reagent showed that H:L178 N Fab contained a relatively low glycan level. Moreover, the H:L178 N mutation did not decrease the binding activity and thermal stability of Fab, and H:L178 N Fab was more resistant to protease digestion than wild-type Fab. The aggregation of Fab induced by pH-shift stress was measured by monitoring the optical density at 350 nm. Although the wild-type Fab showed a large increase in optical density with an increase of protein concentration, no such increase of turbidity during aggregation was found in H:L178 N Fab. These results demonstrated that glycosylation at position 178 of the H-chain constant region of adalimumab Fab can prevent protein aggregation, and therefore serve as a potentially effective platform for drug development.

The Impact of Inadequate Temperature Storage Conditions on Aggregate and Particle Formation in Drugs Containing Tumor Necrosis Factor-Alpha Inhibitors.

PURPOSE: To measure aggregate and particle formation in tumor necrosis factor-alpha (TNF-α) inhibitors etanercept, adalimumab and certolizumab pegol product samples after exposure to freezing temperature conditions similar to storage conditions previously observed in patients' homes. METHODS: TNF-α inhibitors in their original primary and secondary packaging were exposed to 32 freeze-thaw cycles (-10°C for 120min/5°C for 60 min) or continuous low storage temperature (-20°C for 96 h) before thawing at 2-8°C. Non-stressed products were used as controls. The products were analyzed by high pressure size exclusion chromatography (HP-SEC), dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), micro-flow imaging (MFI) and second derivative ultraviolet (UV) spectroscopy. RESULTS: Ten out of twenty-one stressed product samples (47.6%) showed increased particle numbers in the submicron and micron size range when compared to controls. For each product, DLS, MFI and NTA detected an increase in particle level in at least one stressed syringe (both continuous freezing and freeze-thaw), whereas HP-SEC and UV spectroscopy showed no differences between stressed and non-stressed products. CONCLUSION: TNF-α inhibitors are relatively resistant to freezing temperatures similar to storage conditions previously observed in patients' homes. However, almost half of the stressed product samples showed formation of particles in the submicron and micron size range.

Antibodies from combinatorial libraries use functional receptor pleiotropism to regulate cell fates.

To date, most antibodies from combinatorial libraries have been selected purely on the basis of binding. However, new methods now allow selection on the basis of function in animal cells. These selected agonist antibodies have given new insights into the important problem of signal transduction. Remarkably, when some antibodies bind to a given receptor they induce a cell fate that is different than that induced by the natural agonist to the same receptor. The fact that receptors can be functionally pleiotropic may yield new insights into the important problem of signal transduction.