Expression of Multispecific Antibodies.

Bi- and multispecific antibody formats allow the development of new therapeutic strategies to address previously unmet medical needs. However, due to the increased complexity (e.g., the interface design and the presence of multiple binders), such molecules are generally more challenging to express and purify compared to standard monoclonal antibodies (mAbs). We describe here an optimized methodology to express and purify basic bispecific antibodies using the BEAT® interface. This interface allows to generate antibodies with very high levels of heterodimer product (reported titers exceed 10 g/L) and comes with a built-in purification strategy allowing removal of residual levels of undesired product-related impurities (e.g., homodimers and half molecules).

Development of a 10 g/L process for a difficult-to-express multispecific antibody format using a holistic process development approach.

Ichnos has developed a multi-specific antibody platform based on the BEAT® (Bispecific engagement by antibodies based on the T-cell receptor) interface. The increased complexity of the bi- and multi-specific formats generated with this platform makes these molecules difficult-to-express proteins compared to standard monoclonal antibodies (mAbs). This report describes how expression limitations of a bi-specific bi-paratopic BEAT antibody were improved in a holistic approach. An initial investigation allowed identification of a misbalance in the subunits composing the BEAT antibody as the potential root cause. This misbalance was then addressed by a signal peptide optimization, and the overall expression level was increased by the combination of two vector design elements on a single gene vector. Further improvements were made in the selection of cell populations and an upstream (USP) platform process was applied in combination with a cell culture temperature shift. This allowed titer levels of up to 6 g/L to be reached with these difficult-to-express proteins. Furthermore, a high-density seeding process was developed that allowed titers of around 11 g/L for the BEAT antibody, increasing the initial titer by a factor of 10. The approach was successfully applied to a tri-specific antibody with titer levels reaching 10 g/L. In summary, a platform process for difficult-to-express proteins was developed using molecular biology tools, cell line development, upstream process optimization and process intensification.

Viral inactivation for pH-sensitive antibody formats such as multi-specific antibodies.

Recently developed multi-specific antibody formats enable new therapeutic concepts. Conveniently, formats with an Fc domain allow purification in well-established mAb platform processes. However, due to the structural complexity of the formats, the assembled molecules may be sensitive to extreme pH commonly used for viral inactivation. An alternative to low pH incubation for virus inactivation is the use of a mixture of tri-n-butyl phosphate (TnBP, solvent) and Polysorbate 80 (PS80, detergent). While TnBP is toxic, this combination has a long history of use in the manufacturing of human plasma-derived products that are sensitive to low or high pH incubation. Data are provided demonstrating that the solvent/detergent (S/D) treatment using TnBP and PS80 can be successfully used for pH-sensitive, multi-specific antibody formats in the clarified cell culture fluid (CCCF). A different placement of the S/D within the purification process, namely during the capture by Protein A (PA), has been evaluated. This alternative placement allows effective viral inactivation by S/D while preserving the viral reduction and viral inactivation achieved through the PA step itself, enabling the cumulation of these effects. Furthermore, the process alternative simplifies the liquid handling by reducing the added volumes of the required S/D liquids, thus reducing the amount of toxic TnBP to a minimum. Data are shown demonstrating a complete removal of TnBP and PS80 in the process.

Efficacy and Safety of Hylan G-F 20 Versus Intra-Articular Corticosteroids in People with Knee Osteoarthritis: A Systematic Review and Network Meta-Analysis.

BACKGROUND: Direct injection of corticosteroids into the joint is a standard treatment for knee osteoarthritis (OA). However, the treatment is somewhat controversial with regard to the benefit of both single and repeated injections; evidence that they are beneficial comes from small studies that show only modest improvements. The aim of this study was to estimate the short- and long-term clinical efficacy and safety of hylan G-F 20 versus intra-articular corticosteroids (IACS) for the treatment of pain in knee OA using Bayesian network meta-analysis. METHODS: Based on a pre-specified protocol, MEDLINE, Embase, and CENTRAL were searched from inception to June 2018 to identify randomized controlled trials. The Cochrane Collaboration's tool for assessing risk of bias in randomized trials was used to assess the included studies. Hylan G-F 20 and IACS were compared using Bayesian network meta-analysis. Efficacy was evaluated at 1, 3, and 6 months, and at the final follow-up for safety outcomes. A pain hierarchy was used to select 1 pain outcome per study. RESULTS: Forty-two trials were included for analysis. The network meta-analysis of pain showed that hylan G-F 20 may be equivalent to IACS in the short-term, but by 6 months the benefit relative to IACS was statistically significant, standardized mean difference (95% credible interval): -0.13 (-0.26, -0.01). There were no statistical differences in adverse events. CONCLUSIONS: Hylan G-F 20 may perform better in relieving pain at 6 months post-injection compared to IACS. Both agents were relatively well tolerated, with no clear differences in safety.

High molecular weight Intraarticular hyaluronic acid for the treatment of knee osteoarthritis: a network meta-analysis.

BACKGROUND: The 2013 American Academy of Orthopaedic Surgeons (AAOS) guidelines made strong recommendations against intraarticular hyaluronic acid (IAHA) for patients with knee osteoarthritis (OA), as evidence supporting improvements in pain did not meet the minimal clinically important improvement (MCII) threshold. However, there may be important distinctions based on IAHA molecular weight (MW). Hence our objective was to evaluate the efficacy of IAHAs in knee OA based on molecular weight. METHODS: Randomized controlled trials were searched within MEDLINE, Embase, and CENTRAL and selected based on AAOS criteria. A pain measure hierarchy and longest follow-up were used to select one effect size from each trial. Mean differences between interventions were converted to standardized mean differences (SMDs) and incorporated into a random-effects Bayesian network meta-analysis. High MW (HMW) was defined as ≥6000 kDa, and low MW (LMW) as < 750 kDa. RESULTS: HMW IAHA was associated with a statistically significant and possibly clinically significant improvement in pain (SMD - 0.57 (95% credible interval [Crl]: - 1.04, - 0.11), exceeding the - 0.50 MCII threshold. LMW IAHA had a lesser, non-significant improvement (- 0.23, 95% Crl: - 0.67, 0.20). Back-transforming SMDs to the WOMAC pain scale indicated a 14.65 (95% CI: 13.93, 15.62) point improvement over IA placebo, substantially better than the 8.3 AAOS MCII threshold. CONCLUSIONS: Unlike LMW IAHA, HMW IAHA exceeded the MCII threshold for pain relief, suggesting that improvements can be subjectively perceived by the treated patient. Amalgamation of LMW and HMW may have blurred the benefits of IAHA in the past, leading to negative recommendations. Differentiation according to MW offers refined insight for treatment with IAHA.

Comparative efficacy and safety of current therapies for early rheumatoid arthritis: a systematic literature review and network meta-analysis.

OBJECTIVES: This systematic literature review (SLR) and network meta-analysis (NMA) was aimed at comparing the relative efficacy and safety of abatacept (ABA) with other currently recommended therapies for patients with early RA. METHODS: An SLR (January 1998 to June 2018) was conducted including MEDLINE®, Embase, and CENTRAL databases, and grey literature. Population was adults with active RA for ≤2 years treated with biologic DMARDs as monotherapy or in combination with conventional DMARDs. A Bayesian NMA was performed using randomised controlled trials (RCTs) and comparisons for ACR50, DAS28 remission, withdrawal due to adverse events and total withdrawal where reported. RESULTS: Ninety publications pertaining to 69 studies (43 RCTs and 26 observational studies) were identified. Twenty-eight RCTs were eligible to be included in the NMA. ABA as monotherapy was similar to the combination of ABA+methotrexate (MTX) for ACR50 (RR: 0.82 [95% CI 0.51-1.35]), and DAS28 remission (RR: 0.69 [95% CI 0.37-1.3]), as well as for withdrawal due to AEs (RR: 2.35 [95% CI 0.69-7.38]) and all-cause withdrawal (RR: 1.73 [95% CI 0.905-3.35]). ABA as monotherapy and ABA+MTX were both comparable to all other therapies for the main efficacy and safety outcomes. Observational study data reported was congruous with the RCT analysis. CONCLUSIONS: The results of this NMA show similar efficacy and safety between ABA (as monotherapy or in combination with MTX) and other biologics in early RA. Further comparison of different treatment options for early RA is warranted as growing research provides evidence for the application of new novel therapies for RA.

Bilingual approach to online cancer genetics education for Deaf American Sign Language users produces greater knowledge and confidence than English text only: A randomized study.

INTRODUCTION: Deaf American Sign Language-users (ASL) have limited access to cancer genetics information they can readily understand, increasing risk for health disparities. We compared effectiveness of online cancer genetics information presented using a bilingual approach (ASL with English closed captioning) and a monolingual approach (English text). HYPOTHESIS: Bilingual modality would increase cancer genetics knowledge and confidence to create a family tree; education would interact with modality. METHODS: We used a parallel 2:1 randomized pre-post study design stratified on education. 150 Deaf ASL-users ≥18 years old with computer and internet access participated online; 100 (70 high, 30 low education) and 50 (35 high, 15 low education) were randomized to the bilingual and monolingual modalities. Modalities provide virtually identical content on creating a family tree, using the family tree to identify inherited cancer risk factors, understanding how cancer predisposition can be inherited, and the role of genetic counseling and testing for prevention or treatment. 25 true/false items assessed knowledge; a Likert scale item assessed confidence. Data were collected within 2 weeks before and after viewing the information. RESULTS: Significant interaction of language modality, education, and change in knowledge scores was observed (p = .01). High education group increased knowledge regardless of modality (Bilingual: p < .001; d = .56; Monolingual: p < .001; d = 1.08). Low education group increased knowledge with bilingual (p < .001; d = .85), but not monolingual (p = .79; d = .08) modality. Bilingual modality yielded greater confidence creating a family tree (p = .03). CONCLUSIONS: Bilingual approach provides a better opportunity for lower educated Deaf ASL-users to access cancer genetics information than a monolingual approach.

The concerted impact of domestication and transposon insertions on methylation patterns between dogs and grey wolves.

The process of domestication can exert intense trait-targeted selection on genes and regulatory regions. Specifically, rapid shifts in the structure and sequence of genomic regulatory elements could provide an explanation for the extensive, and sometimes extreme, variation in phenotypic traits observed in domesticated species. Here, we explored methylation differences from >24 000 cytosines distributed across the genomes of the domesticated dog (Canis familiaris) and the grey wolf (Canis lupus). PCA and model-based cluster analyses identified two primary groups, domestic vs. wild canids. A scan for significantly differentially methylated sites (DMSs) revealed species-specific patterns at 68 sites after correcting for cell heterogeneity, with weak yet significant hypermethylation typical of purebred dogs when compared to wolves (59% and 58%, P < 0.05, respectively). Additionally, methylation patterns at eight genes significantly deviated from neutrality, with similar trends of hypermethylation in purebred dogs. The majority (>66%) of differentially methylated regions contained or were associated with repetitive elements, indicative of a genotype-mediated trend. However, DMSs were also often linked to functionally relevant genes (e.g. neurotransmitters). Finally, we utilized known genealogical relationships among Yellowstone wolves to survey transmission stability of methylation marks, from which we found a substantial fraction that demonstrated high heritability (both H(2) and h(2 ) > 0.99). These analyses provide a unique epigenetic insight into the molecular consequences of recent selection and radiation of our most ancient domesticated companion, the dog. These findings suggest selection has acted on methylation patterns, providing a new genomic perspective on phenotypic diversification in domesticated species.

A novel membrane sensor controls the localization and ArfGEF activity of bacterial RalF.

The intracellular bacterial pathogen Legionella pneumophila (Lp) evades destruction in macrophages by camouflaging in a specialized organelle, the Legionella-containing vacuole (LCV), where it replicates. The LCV maturates by incorporating ER vesicles, which are diverted by effectors that Lp injects to take control of host cell membrane transport processes. One of these effectors, RalF, recruits the trafficking small GTPase Arf1 to the LCV. LpRalF has a Sec7 domain related to host ArfGEFs, followed by a capping domain that intimately associates with the Sec7 domain to inhibit GEF activity. How RalF is activated to function as a LCV-specific ArfGEF is unknown. We combined the reconstitution of Arf activation on artificial membranes with cellular expression and Lp infection assays, to analyze how auto-inhibition is relieved for LpRalF to function in vivo. We find that membranes activate LpRalF by about 1000 fold, and identify the membrane-binding region as the region that inhibits the Sec7 active site. It is enriched in aromatic and positively charged residues, which establish a membrane sensor to control the GEF activity in accordance with specific lipid environments. A similar mechanism of activation is found in RalF from Rickettsia prowazekii (Rp), with a different aromatic/charged residues ratio that results in divergent membrane preferences. The membrane sensor is the primary determinant of the localization of LpRalF on the LCV, and drives the timing of Arf activation during infection. Finally, we identify a conserved motif in the capping domain, remote from the membrane sensor, which is critical for RalF activity presumably by organizing its active conformation. These data demonstrate that RalF proteins are regulated by a membrane sensor that functions as a binary switch to derepress ArfGEF activity when RalF encounters a favorable lipid environment, thus establishing a regulatory paradigm to ensure that Arf GTPases are efficiently activated at specific membrane locations.

Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2.

The mechanisms whereby guanine nucleotide exchange factors (GEFs) coordinate their subcellular targeting to their activation of small GTPases remain poorly understood. Here we analyzed how membranes control the efficiency of human BRAG2, an ArfGEF involved in receptor endocytosis, Wnt signaling, and tumor invasion. The crystal structure of an Arf1-BRAG2 complex that mimics a membrane-bound intermediate revealed an atypical PH domain that is constitutively anchored to the catalytic Sec7 domain and interacts with Arf. Combined with the quantitative analysis of BRAG2 exchange activity reconstituted on membranes, we find that this PH domain potentiates nucleotide exchange by about 2,000-fold by cumulative conformational and membrane-targeting contributions. Furthermore, it restricts BRAG2 activity to negatively charged membranes without phosphoinositide specificity, using a positively charged surface peripheral to but excluding the canonical lipid-binding pocket. This suggests a model of BRAG2 regulation along the early endosomal pathway that expands the repertoire of GEF regulatory mechanisms. Notably, it departs from the auto-inhibitory and feedback loop paradigm emerging from studies of SOS and cytohesins. It also uncovers a novel mechanism of unspecific lipid-sensing by PH domains that may allow sustained binding to maturating membranes.