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Proteins are the building blocks of all living organisms enabling us to function and survive. There are more than 100,000 different proteins in the human body performing a variety of vital tasks. Examples of essential proteins are antibodies defending our body against foreign invaders and hemoglobulin responsible for importing oxygen to our cells and exporting carbon dioxide out from our cells. Consequently, mutations leading to dysfunctional proteins is the cause of many known diseases. Fortunately, the advancement of modern medicine has enabled proteins also to be employed as therapeutics to treat and cure various conditions. For instance, human insulin is recombinantly produced in the bacterium E. coli and is used as a biopharmaceutical to treat patients with Diabetes. The increased knowledge about diseases, their cause, and what cellular pathway to target has led to the discovery of many novel and complex biologics. Hence, the manufacturing of biopharmaceuticals is a rapidly emerging field that enables the production of complex molecules that are target-specific, effective, and highly active in the human body. Mammalian cell lines are often the preferred cell factories for manufacturing biologics since they generate proteins with human-like post-translational modifications, which are often essential features to obtain functional, safe, and effective therapeutics. Unfortunately, these life-saving biologics are costly, making them affordable for a fraction of patients worldwide. Therefore, one of the goals of the biotech industry is to make accessible biologics for everyone who needs it regardless of financial background. One way to achieve this goal is to engineer mammalian cell factories to improve the quantity and quality of biopharmaceuticals while reducing the production cost. The results presented in this thesis are the outcome of five different studies aiming to improve and balance the expression levels of recombinant proteins in mammalian cell lines. In th, Proteiner är livets byggstenar och därav nödvändiga för vår överlevnad. Det finns mer än 100,000 olika proteiner i människokroppen som utför åtskilliga och livsviktiga funktioner. Två exempel på viktiga och allmänkända proteiner är antikroppar, kroppens soldater som förvarar oss mot främmande mikroorganismer och hemoglobin som transporterar syre till kroppens olika organ och för bort den giftiga koldioxiden från cellerna. Följaktligen är mutationer som leder till dysfunktionella proteiner den främsta orsaken till majoriteten av kända sjukdomar. Lyckligtvis har den stora framgången inom forskning och medicin möjliggjort användandet av proteiner som läkemedel för behandling av olika sjukdomar. Till exempel är insulin som ett protein och används som läkemedel för diabetiker och som produceras rekombinant i bakterien E. coli. Den ökade kunskapen om sjukdomar, hur de uppkommit och vilka cellulära mekanismer som är viktiga för deras utveckling, har lett till upptäckten av flera nya och komplexa biologiska läkemedel. Detta har lett till att tillverkningen av bioläkemedel har blivit ett snabbt växande område som möjliggör produktion av komplexa molekyler som är målspecifika, effektiva och mycket aktiva i människokroppen. Däggdjurscellinjer är ofta det mest förekommande typen av cellfabriker för tillverkning av biologiska läkemedel då de är kapabla att generera proteiner med modifieringar som liknar det humana och som ofta är väsentliga för att erhålla funktionella, säkra och effektiva läkemedel. Tyvärr är dessa livräddande biologiska läkemedel mycket dyra, vilket gör dem tillgängliga för endast en bråkdel av patienter över hela världen. Därför är ett av målen för bioteknikindustrin att göra biologiska läkemedel tillgängliga för alla som behöver det oavsett ekonomisk bakgrund. Ett sätt att uppnå detta mål är att framställa effektivare däggdjurscellfabriker för att förbättra mängden och, QC 2021-11-19

Non-immunoglobulin scaffolds represent a proven group of small affinity proteins that can be engineered in vitro to similar affinity and potency as monoclonal antibodies. Several novel candidate biotherapeutics that exploit the potential advantages scaffold proteins hold over larger and more complex antibodies have been developed over the past decade. The ease of using small and robust binding proteins as flexible and modular building blocks has led to the development of a wide range of innovative approaches to combine them in various bi- and multispecific formats. This progress is expected to aid the ongoing challenge of identifying niche applications where clear differentiation from antibody-based molecules will be key to success. Given the many engineering options that are available for non-immunoglobulin scaffold proteins, they have potential to not only complement but probably also surpass antibodies in certain applications., QC 20190403

Angiogenesis denotes the formation of new blood vessels from pre-existing vasculature. Progression of diseases such as cancer and several ophthalmological disorders may be promoted by excess angiogenesis. Novel therapeutics to inhibit angiogenesis and diagnostic tools for monitoring angiogenesis during therapy, hold great potential for improving treatment of such diseases. We have previously generated so-called biparatopic Affibody constructs with high affinity for the vascular endothelial growth factor receptor-2 (VEGFR2), which recognize two non-overlapping epitopes in the ligand-binding site on the receptor. Affibody molecules have previously been demonstrated suitable for imaging purposes. Their small size also makes them attractive for applications where an alternative route of administration is beneficial, such as topical delivery using eye drops. In this study, we show that decreasing linker length between the two Affibody domains resulted in even slower dissociation from the receptor. The new variants of the biparatopic Affibody bound to VEGFR2-expressing cells, blocked VEGFA binding, and inhibited VEGFA-induced signaling of VEGFR2 over expressing cells. Moreover, the biparatopic Affibody inhibited sprout formation of endothelial cells in an in vitro angiogenesis assay with similar potency as the bivalent monoclonal antibody ramucirumab. This study demonstrates that the biparatopic Affibody constructs show promise for future therapeutic as well as in vivo imaging applications., QC 20160428

Emerging strategies in cancer biotherapy include the generation and application of bispecific antibodies, targeting two tumor-associated antigens for improved tumor selectivity and potency. Here, an alternative format for bispecific molecules was designed and investigated, in which two Affibody molecules were linked by an albumin-binding domain (ABD). Affibody molecules are small (6 kDa) affinity proteins and this new format allows for engineering of molecules with similar function as full-length bispecific antibodies, but in a dramatically smaller size (around eight-fold smaller). The ABD was intended to function both as a tag for affinity purification as well as for in vivo half-life extension in future preclinical and clinical investigations. Affinity-purified bispecific Affibody molecules, targeting HER2 and HER3, showed simultaneous binding to the three target proteins (HER2, HER3, and albumin) when investigated in biosensor assays. Moreover, simultaneous interactions with the receptors and albumin were demonstrated using flow cytometry on cancer cells. The bispecific Affibody molecules were also able to block ligand-induced phosphorylation of the HER receptors, indicating an anti-proliferative effect. We believe that this compact and flexible format has great potential for developing new potent bispecific affinity proteins in the future, as it combines the benefits of a small size (e.g. improved tissue penetration and reduced cost of goods) with a long circulatory half-life., QC 20141013

The albumin-binding domain is a small, three-helical protein domain found in various surface proteins expressed by gram-positive bacteria. Albumin binding is important in bacterial pathogenesis and several homologous domains have been identified. Such albumin-binding regions have been used for protein purification or immobilization. Moreover, improvement of the pharmacokinetics, through the non-covalent association to albumin, by fusing such domains to therapeutic proteins has been shown to be successful. Domains derived from streptococcal protein G and protein PAB from Finegoldia magna, which share a common origin and therefore represent an interesting evolutionary system, have been thoroughly studied structurally and functionally. Their albumin-binding sites have been mapped and these domains form the basis for a wide range of protein engineering approaches. By substitution-mutagenesis they have been engineered to achieve a broader specificity, an increased stability or an improved binding affinity, respectively. Furthermore, novel binding sites have been incorporated either by replacing the original albumin-binding surface, or by complementing it with a novel interaction interface. Combinatorial protein libraries, where several residues have been randomized simultaneously, have generated a large number of new variants with desired binding characteristics. The albuminbinding domain has also been utilized to explore the relationship between three-dimensional structure and amino acid sequence. Proteins with latent structural information built into their sequence, where a single amino acid substitution shifts the equilibrium in favor of a different fold with a new function, have been designed. Altogether, these examples illustrate the versatility of the albumin-binding domain as a scaffold for protein engineering., QC 20140911

Affinity proteins based on small scaffolds are currently emerging as alternatives to antibodies for therapy. Similarly to antibodies, they can be engineered to have high affinity for specific proteins. A potential problem with small proteins and peptides is their short in vivo circulation time, which might limit the therapeutic efficacy. To circumvent this issue, we have engineered bispecificity into an albumin-binding domain (ABD) derived from streptococcal Protein G. The inherent albumin binding was preserved while the opposite side of the molecule was randomized for selection of high-affinity binders. Here we present novel ABD variants with the ability to bind to the epidermal growth factor receptor 3 (ErbB3). Isolated candidates were shown to have an extraordinary thermal stability and affinity for ErbB3 in the nanomolar range. Importantly, they were also shown to retain their affinity to albumin, hence demonstrating that the intended strategy to engineer bispecific single-domain proteins against a tumor-associated receptor was successful. Moreover, competition assays revealed that the new binders could block the natural ligand Neuregulin-1 from binding to ErbB3, indicating a potential anti-proliferative effect. These new binders thus represent promising candidates for further development into ErbB3-signaling inhibitors, where the albumin interaction could result in prolonged in vivo half-life., QC 20131018

Aggregation of therapeutic bispecific antibodies negatively affects the yield, shelf-life, efficacy and safety of the product. Pairs of stable Chinese hamster ovary cell lines produced two difficult- to-express bispecific antibodies with different levels of aggregated product (10-75% aggregate) in a miniaturized bioreactor system. Here, we analyse the cellular response and link to product aggregation by comparative transcriptome analysis of these CHO cells, to define biological causes and infer strategies to improve yield and quality. Differential expression- and gene set analysis revealed upregulated proteosomal degradation, unfolded protein response and autophagy processes to be correlated with reduction of protein aggregation. Fourteen candidate genes with potential to reduce aggregation were co-expressed in the stable clones for validation. Of these, HSP90B1, DDIT3, AK1S1, and ATG16L1, were found to significantly lower aggregation in the stable producers and two (HSP90B1 and DNAJC3) increased trastuzumab titres by 50% each during transient expression. We suggest our approach to be of general use for defining aggregation bottlenecks in CHO.

Aggregation of therapeutic bispecific antibodies negatively affects the yield, shelf-life, efficacy and safety of the product. Pairs of stable Chinese hamster ovary cell lines produced two difficult- to-express bispecific antibodies with different levels of aggregated product (10-75% aggregate) in a miniaturized bioreactor system. Here, we analyse the cellular response and link to product aggregation by comparative transcriptome analysis of these CHO cells, to define biological causes and infer strategies to improve yield and quality. Differential expression- and gene set analysis revealed upregulated proteosomal degradation, unfolded protein response and autophagy processes to be correlated with reduction of protein aggregation. Fourteen candidate genes with potential to reduce aggregation were co-expressed in the stable clones for validation. Of these, HSP90B1, DDIT3, AK1S1, and ATG16L1, were found to significantly lower aggregation in the stable producers and two (HSP90B1 and DNAJC3) increased trastuzumab titres by 50% each during transient expression. We suggest our approach to be of general use for defining aggregation bottlenecks in CHO.

Aggregation of therapeutic bispecific antibodies negatively affects the yield, shelf-life, efficacy and safety of the product. Pairs of stable Chinese hamster ovary cell lines produced two difficult- to-express bispecific antibodies with different levels of aggregated product (10-75% aggregate) in a miniaturized bioreactor system. Here, we analyse the cellular response and link to product aggregation by comparative transcriptome analysis of these CHO cells, to define biological causes and infer strategies to improve yield and quality. Differential expression- and gene set analysis revealed upregulated proteosomal degradation, unfolded protein response and autophagy processes to be correlated with reduction of protein aggregation. Fourteen candidate genes with potential to reduce aggregation were co-expressed in the stable clones for validation. Of these, HSP90B1, DDIT3, AK1S1, and ATG16L1, were found to significantly lower aggregation in the stable producers and two (HSP90B1 and DNAJC3) increased trastuzumab titres by 50% each during transient expression. We suggest our approach to be of general use for defining aggregation bottlenecks in CHO.

Aggregation of therapeutic bispecific antibodies negatively affects the yield, shelf-life, efficacy and safety of the product. Pairs of stable Chinese hamster ovary cell lines produced two difficult- to-express bispecific antibodies with different levels of aggregated product (10-75% aggregate) in a miniaturized bioreactor system. Here, we analyse the cellular response and link to product aggregation by comparative transcriptome analysis of these CHO cells, to define biological causes and infer strategies to improve yield and quality. Differential expression- and gene set analysis revealed upregulated proteosomal degradation, unfolded protein response and autophagy processes to be correlated with reduction of protein aggregation. Fourteen candidate genes with potential to reduce aggregation were co-expressed in the stable clones for validation. Of these, HSP90B1, DDIT3, AK1S1, and ATG16L1, were found to significantly lower aggregation in the stable producers and two (HSP90B1 and DNAJC3) increased trastuzumab titres by 50% each during transient expression. We suggest our approach to be of general use for defining aggregation bottlenecks in CHO.

Aggregation of therapeutic bispecific antibodies negatively affects the yield, shelf-life, efficacy and safety of the product. Pairs of stable Chinese hamster ovary cell lines produced two difficult- to-express bispecific antibodies with different levels of aggregated product (10-75% aggregate) in a miniaturized bioreactor system. Here, we analyse the cellular response and link to product aggregation by comparative transcriptome analysis of these CHO cells, to define biological causes and infer strategies to improve yield and quality. Differential expression- and gene set analysis revealed upregulated proteosomal degradation, unfolded protein response and autophagy processes to be correlated with reduction of protein aggregation. Fourteen candidate genes with potential to reduce aggregation were co-expressed in the stable clones for validation. Of these, HSP90B1, DDIT3, AK1S1, and ATG16L1, were found to significantly lower aggregation in the stable producers and two (HSP90B1 and DNAJC3) increased trastuzumab titres by 50% each during transient expression. We suggest our approach to be of general use for defining aggregation bottlenecks in CHO.