The glycosylation of anti-rhIFN-α2b recombinant antibodies influences the antigen-neutralizing activity

OBJECTIVES

The influence of glycosylation on the antigen-neutralizing ability of two potential biotherapeutic anti-human IFN-α2b antibodies composed by murine and humanized single-chain Fv fused to human Fcγ1 (chimeric and humanized scFv-Fc, respectively) was studied.

RESULTS

Chimeric antibodies produced in CHO-K1 and HEK293 mammalian cells showed no differences in the antigen-antibody affinity but demonstrated differences in the in vitro neutralization of IFN-α2b activity. On the other hand, the humanized antibodies produced in the same cell types showed differences in both the antigen-antibody affinity and the antigen-neutralizing ability. These differences are due to the scFv domain, as evidenced by its expression in CHO-K1 and HEK293 cells. In order to determine if the Fc glycosylation influences the antigen binding ability, both parameters were analyzed on chimeric and humanized deglycosylated scFv-Fc. Surprisingly, no differences in the antigen-antibody affinity were observed, but differences in the antigen-neutralizing ability of both chimeric and humanized antibodies, and their respectively deglycosylated glycoforms were found.

CONCLUSIONS

Fc glycosylation influences the antigen neutralization ability of two anti-rhIFN-α2b recombinant antibodies. Although affinity is the widely accepted parameter to analyze antibody antigen binding, it does not appear to be sufficient to describe the behavior of recombinant antibodies in vitro. This work contributes with a high impact knowledge to develop therapeutic recombinant antibodies where glycosylation and producer cell lines must be taken into account for their influence on the antigen binding capacity and not only for their impact on the effector properties as it has been historically considered for antibodies.

Glycosylation and antiproliferative activity of hyperglycosylated IFN-α2 potentiate HEK293 cells as biofactories

Both CHO and HEK cells are interesting hosts for the production of biotherapeutics due to their ability to introduce post-translational modifications such as glycosylation. Even though oligosaccharide structures attached to proteins are conserved among eukaryotes, many differences have been found between therapeutic glycoproteins expressed in hamster and human derived cells. In this work, a hyperglycosylated IFN-α2b mutein (IFN4N) was produced in CHO and HEK cell lines and an extensive characterization of their properties was performed. IFN4N_CHO exhibited a higher average molecular mass and more acidic isoforms compared to IFN4N_HEK. In agreement with these results, a 2-times higher sialic acid content was found for IFN4N_CHO in comparison with the HEK-derived protein. This result was in agreement with monosaccharide quantification and glycan's analysis using WAX chromatography and HILIC coupled to mass spectrometry; all methods supported the existence of highly sialylated and also branched structures for IFN4N_CHO glycans, in contrast with smaller and truncated structures among IFN4N_HEK glycans. Unexpectedly, those remarkable differences in the glycosylation pattern had not a considerable impact on the clearance rate of both molecules in rats. In fact, although IFN4N_HEK reached maximum plasma concentration 3-times faster than IFN4N_CHO, their elimination profile did not differ significantly. Also, despite the in vitro antiviral specific biological activity of both proteins was the same, IFN4N_HEK was more efficient as an antiproliferative agent in different tumor-derived cell lines. Accordingly, IFN4N_HEK showed a higher in vivo antitumor activity in animal models. Our results show the importance of an appropriate host selection to set up a bioprocess and potentiate the use of HEK293 cells for the production of a new hyperglycosylated protein-based pharmaceutical.

Establishment of a design space for biopharmaceutical purification processes using DoE

Recent trends in the pharmaceutical sector are changing the way protein purification processes are designed and executed, moving from operating the process in a fixed point to allowing a permissible region in the operating space known as design space. This trend is driving product development to design quality into the manufacturing process (Quality by Design) and not to rely exclusively on testing quality in the product. A typical purification step has numerous operating parameters that can impact its performance. Therefore, optimization and robustness analysis in purification processes can be time-consuming since they are mainly grounded on experimental work. A valuable approach consists in the combination of an adequate risk analysis technique for selecting the relevant factors influencing process performance and the design of experiment methodology. The latter allows for many process variables which can be studied at the same time; thus, the number of tests will be reduced in comparison with the conventional approach based on trial and error. These multivariate studies permit a detailed exploration in the experimental range and lay the foundation of Quality by Design principles application. This article outlines a recommended sequence of activities toward the establishment of an expanded design space for a purification process.

Novel chemometric strategy based on the application of artificial neural networks to crossed mixture design for the improvement of recombinant protein production in continuous culture

The optimal blends of six compounds that should be present in culture media used in recombinant protein production were determined by means of artificial neural networks (ANN) coupled with crossed mixture experimental design. This combination constitutes a novel approach to develop a medium for cultivating genetically engineered mammalian cells. The compounds were collected in two mixtures of three elements each, and the experimental space was determined by a crossed mixture design. Empirical data from 51 experimental units were used in a multiresponse analysis to train artificial neural networks which satisfy different requirements, in order to define two new culture media (Medium 1 and Medium 2) to be used in a continuous biopharmaceutical production process. These media were tested in a bioreactor to produce a recombinant protein in CHO cells. Remarkably, for both predicted media all responses satisfied the predefined goals pursued during the analysis, except in the case of the specific growth rate (mu) observed for Medium 1. ANN analysis proved to be a suitable methodology to be used when dealing with complex experimental designs, as frequently occurs in the optimization of production processes in the biotechnology area. The present work is a new example of the use of ANN for the resolution of a complex, real life system, successfully employed in the context of a biopharmaceutical production process.

Temperature Reduction in Cultures of hGM-CSF-expressing CHO Cells: Effect on Productivity and Product Quality

We have demonstrated that temperature reduction from 37 to 33 degrees C in the culture of a CHO cell line producing recombinant human granulocyte macrophage colony stimulating factor (CHO-K1-hGM-CSF) leads to a reduced growth rate, increased cell viability, improved cellular productivity, and decreased cell metabolism. In the present study, CHO-K1-hGM-CSF cells were cultured in a biphasic mode: first, a 37 degrees C growth phase for achieving a high cell number, followed by a production phase where the culture temperature was shifted to 33 degrees C. The maximum cell density was not affected after temperature reduction while cell viability remained above 80% for a further 3.7 days in the culture kept at the lower temperature, when compared to the control culture maintained at 37 degrees C. Furthermore, the total rhGM-CSF production increased 6 times in the culture shifted to 33 degrees C. Because the quality and hence the in vivo efficacy of a recombinant protein might be affected by numerous factors, we have analyzed the N- and O-glycosylation of the protein produced under both cell culture conditions using high-pH anion-exchange chromatography and complementary mass spectrometry techniques. The product quality data obtained from the purified protein preparations indicated that decreasing temperature had no significant effect on the rhGM-CSF glycosylation profiles, including the degree of terminal sialylation. Moreover, both preparations exhibited the same specific in vitro biological activity. These results revealed that the employed strategy had a positive effect on the cell specific productivity of CHO-K1-hGM-CSF cells without affecting product quality, representing a novel procedure for the rhGM-CSF production process.

Rational selection of an antibody probe to detect the heterogeneous collection of CHO-derived rhGM-CSF glycoforms

Six anti-E. coli rhGM-CSF monoclonal antibodies were generated using hybridoma technology. One of these showed identical affinity for the CHO and E. coli-derived cytokine (dissociation constants of 0.14 +/- 0.01 nM and 0.13 +/- 0.01 nM, respectively), mapping an epitope that is not hindered by carbohydrates. The antibody was used to develop a simple, specific and sensitive competitive ELISA to quantify the entire set of rhGM-CSF glycoforms (detection limit of 780 pg/ml) and it was successful as an affinity ligand to purify them. Therefore, this particular antibody is a useful, reliable and reagent for most immunochemical purposes with the aim of detecting, quantifying and purifying the highly heterogeneous collection of the CHO-derived rhGM-CSF isoforms.

N- and O-linked carbohydrates and glycosylation site occupancy in recombinant human granulocyte-macrophage colony-stimulating factor secreted by a Chinese hamster ovary cell line

GM-CSF is one of several naturally occurring glycoproteins that regulate leukocyte production, migration and function. It has been produced in different cell types, with different properties that depend on the production process used. The purpose of this work was to characterize the recombinant human GM-CSF from an engineered Chinese hamster ovary cell line grown in suspension and as adherent culture for the identification of the glycosylation sites and the definition of the glycosidic moiety, including the degree of site occupancy. Both preparations exhibited size heterogeneity in SDS/PAGE with multiple bands containing glycoprotein forms with either two or one N-glycosylation sites occupied. Minor low molecular mass forms completely lacked N-linked oligosaccharides but contained 1-3 O-linked glycans. Twelve differently charged isoforms were detected in isoelectric focusing gels. At least 16 glycoforms, differing in the number of Hex-HexNAc units (Deltam 365 Da), were detected in MALDI-TOF MS spectra of the desialylated GM-CSFs. MALDI-TOF MS and HPAEC-PAD analysis indicated the presence of predominantly tri- and tetraantennary N-linked oligosaccharide chains with and without N-acetyllactosamine repeat units and some 10% of biantennary oligosaccharides, all containing more than 90% proximal alpha1-6-linked fucose. The oligosaccharide patterns of both GM-CSF preparations were found to be very similar. More than 90% of terminal galactose residues of the N-glycans were found alpha2-3 sialylated with NeuNAc (93%) or NeuNGc (7%). Site specific glycosylation was analysed by electrospray ionization MS and it was found that in the mono glycosylated GM-CSF form more than 90% of the Asn37 were occupied by N-glycans. O-glycosylation at the N-terminus of the polypeptide was detected at Ser7 and Ser9 or Thr10, in the predominantly doubly O-glycosylated glycoprotein form. In the triply modified GM-CSF molecules, Ser5 was additionally O-glycosylated. The major difference between both preparations was found in the MALDI spectra of the desialylated glycoproteins, revealing a higher proportion of forms with a single N-glycosylation site occupied in the preparation derived from suspension culture. ESI-MS and MALDI-MS analysis of endoproteolytically cleaved peptides as well as MALDI-TOF MS of the intact glycoprotein demonstrated the N- and C-termini integrity of the GM-CSF preparations.

The role of pneumatic compression in the treatment of postmastectomy lymphedema. A randomized phase III study

BACKGROUND

Pneumatic compression is a frequently prescribed physical therapy for patients affected by postmastectomy lymphedema but, despite its wide use, its efficacy has not been demonstrated in phase III studies. We performed a randomized study comparing pneumatic compression versus no treatment in patients with postmastectomy lymphedema.

PATIENTS AND METHODS

Patients with monolateral postmastectomy lymphedema were randomized to receive two cycles of intermittent pneumatic compression (PC group), i.e., five two-hour sessions per week for two weeks, to be repeated after a five-week interval, or to no treatment (control group). The patients in both groups were instructed as to the prophylactic hygienic care of the limb. Lymphedema was assessed by the sum of differences in circumference measurements between affected and normal limbs ('delta'). Response was defined as a > or = 25% reduction in delta value.

RESULTS

Eighty patients entered the study. No statistically significant differences in response rates between the two groups were observed: 20% in the control group (95% CI: 9%-36%), 25% in the PC group (95% CI: 13%-41%, P = 0.59). The absolute mean decrease in delta value was 1.9 +/- 3.7 cm in the PC group and 0.5 +/- 3.3 cm in the control group.

CONCLUSIONS

We demonstrated that intermittent pneumatic compression has a limited clinical role in the treatment of postmastectomy lymphedema. Efforts to prevent this complication should be undertaken.

Colorectal, lung, and breast cancer care during the three years following the diagnosis: a population-based study

AIMS

We evaluated a number of basic parameters of care during hospitalization that contribute to the total cost of therapy during the 3 years after the first diagnosis of cancer.

METHODS

The study examined a sample of cases of cancer of the colon-rectum (164 cases), lung (160 cases) and breast (144 cases) diagnosed in 1987, taken from the data base of the Tuscany Cancer Registry. All the information collected by the Registry was examined and the sample was further validated by reviewing original clinical records. The agreement between the two sources was very high, confirming the adequacy of the Registry as a source of information. The parameters evaluated for each patient were the number of cytohistologic examinations, surgery, hospital admissions and days spent in hospital during the 3 follow-up years.

RESULTS

The average number of admittances in 3 years was 1.93 for colorectal, 3.39 for lung and 2.15 for breast cancer. The mean number of days spent in hospital in the 3 follow-up years was 39.9 for colorectal, 50.1 for lung and 21.1 for breast cancer. The parameters differed among subjects still alive, those deceased and those in various stages of the illness.

CONCLUSIONS

The costs of the time spent in hospital, based on the number of days during the first 3 years of the illness, were higher in cases of lung cancer than of the other sites, and more so for patients diagnosed in an advanced phase of the disease.

[Sulodexide in the prevention of post-mastectomy lymphedema]

Post-mastectomy lymphedema of the upper limb, that can be noticed by 10 to 20 percent of patients with breast cancer, is usually related to some risk factors: use of radiotherapy on the axilla, obesity, venous outflow obstruction, delayed wound healing or infection. The most important contributing factor to postsurgical edema is the development of lymphangitis in the upper limb. Although literature contains numerous accounts on the use of pharmacological agents for the treatment of postmastectomy lymphedema, the results are not satisfactory in term of clinical response and side effects. In the present study we investigate tolerability and feasibility of the use of suledexide in patients, submitted to mastectomy for breast cancer, with an initial lymphedema of the limb omolateral to surgery or other risk factors for the development of a clinical remarkable lymphedema. Our results show that sulodexide is a very satisfactory therapy in term of lack of side effects and good compliance.

Combined management in the treatment of epidoxorubicin extravasation. A case report

Inadvertent extravasation during intravenous antitumor therapy is not an unusual complication and can cause damage ranging from minor erythema to severe local necrosis. The appropriate management of these iatrogenic accidents as a part of supportive care in oncology has been addressed by several experimental studies, but there has been little clinical study and no conclusive evidence on the best therapeutic strategies to adopt. The case reported here of a patient suffering from severe soft-tissue injury caused by extravasation of epidoxorubicin demonstrates the usefulness of a combined management (medical, surgical and rehabilitative) in the appropriate care of extravasation.

Treatment of metastatic colorectal carcinoma with lymphoblastoid interferon and 5-fluorouracil: data of a phase II study

Many clinical trials have tested the combination of 5-fluorouracil and recombinant alpha-interferons in metastatic colorectal carcinoma. The efficacy of 5-fluorouracil and lymphoblastoid interferon was evaluated in a phase II study in which 31 patients with advanced colorectal carcinoma were enrolled. 5-Fluorouracil was administered at the dose of 600 mg/sqm bolus weekly and lymphoblastoid interferon was given intramuscularly at 3 million units every two days. All patients were evaluable for toxicity. Thirty patients were available for response: no complete response was recorded, three patients reached a partial response (10%), three a minor response (10%) and 18 progressed (59.4%). Overall median survival was 8 months. No grade IV toxicity was observed: in 2 patients grade III occurred and in 8 patients grade III fever and fatigue attributable to interferon developed. It appears that this combination does not yield better results than 5-fluorouracil alone.

An analysis of prognostic factors in response to conservative treatment of postmastectomy lymphedema

Postmastectomy lymphedema of the upper limb is usually managed conservatively. Patients are often advised to use elastic bandages or sleeves during the day: elastic compression is, in fact, generally considered the mainstay of lymphedema therapy by authors who advocate the addition of cyclical instrumental or physical treatments, such as pneumatic compression or manual lymphatic drainage. The results of elastic compression, however, have never been extensively analyzed. In the present study, we describe the patterns of response during six months of use of a standard elastic sleeve in a series of 120 patients with postmastectomy lymphedema. Univariate and multivariate analyses were performed to identify possible prognostic factors for a better or worse response. Overall, limb measurements were reduced by 14.7 percent, with weight gain after surgical treatment resulting as the only significant independent negative factor: patients who did not increase weight after mastectomy achieved nearly a 25 percent reduction of lymphedema. These results should be considered during the selection of patients for protocols of lymphedema treatment and the analysis of results.

Conservative treatment of postmastectomy lymphedema: a controlled, randomized trial

A controlled, randomized trial was carried out to evaluate the effectiveness of a new conservative treatment for postmastectomy lymphedema. Seventy-four patients were randomized to wear only an elastic sleeve for six months (group A) or to receive additionally an induction treatment with electrically stimulated lymphatic drainage (group B). The evaluation of results was focused not only on the mean variations in limb measurements in the two groups, but also on the frequency of clinically significant reductions of lymphedema (i.e., at least 25% compared to the initial values). A mean reduction of limb girth of about 17% was obtained in both groups, without significant differences between the two treatments. An 'objective response', however, was not achieved by the majority of patients. On the other hand, compliance to therapy was good and a significant result could be obtained simply and economically also in the group of patients treated only with the elastic sleeve.

[Convergence and divergence between morphology and karyology in related species of the genus Vicia]

Karyological polymorphism is generally the rule in related species of genus Vicia, as has been frequently shown in many entities of its comprehensive species; therefore a correspondence of phenotypic and karyotypic characters is rather rare. Two cases are described here, in which both external morphological and internal karyological features, are correlated. These data have been obtained through biometric and karyotypic studies, carried out both on the perennials V. onobrychioides and V. altissima, and on the annuals V. villosa ssp. varia and V. benghalensis. In both perennials the chromosomes were rather long, the nucleolar constriction was on the longest couple of chromosomes, and even the satellite was of the same type; in both annuals the chromosomes were short, the nucleolar constriction was on the shortest couple of chromosomes, and the satellite was large in comparison to the arm to which it was connected. These similarities of the karyotypes are important because they may make easier a possible experimental cross-breed of the abovementioned entities.

Irrigation for colostomized cancer patients: a rational approach

Management of a colostomy by irrigation is simple and effective. Five hundred and nine patients having a colostomy for rectal cancer during the last 10 years were assessed by our Rehabilitation Department as potential candidates for irrigation. Fifty-two patients were considered unsuitable and 40 refused to learn the technique. The remaining 417 (82%) patients adopted the irrigation method. Of these, 97% achieved full continence of periods of 24 to 48 h. There was no case of colonic perforation. The median duration of irrigation was 230 days; 31.6% had been irrigating from 1 to 5 years and 10.3% for more than 5 years. There was a reduction of more than 50%/24 h in the number of appliances used by patients. Irrigation is a simple, safe and cost-effective means of managing a colostomy. With careful selection of patients, irrigation should be recommended as a routine part of rehabilitation.

Colostomy irrigation in the elderly. Effective recovery regardless of age

One hundred forty elderly cancer outpatients with colostomy in the authors' rehabilitation department were included in an analysis of the feasibility, effectiveness, and safety of periodic irrigation of remaining colon with lukewarm tap water with the aim of regaining full continence. Sixteen patients did not have a sufficiently long remaining bowel (cecostomy, transverse colostomy) and 17 were considered unsuitable to learn the technique because of advanced neoplastic disease with poor life expectancy, intercurrent disease, or stomal problems. One hundred seven patients were proposed to perform the irrigation: 17 refused to do so with the remaining 90 able to learn the method without problems. Nearly all patients achieved full continence for at least 24 hours. Three patients refused to continue, and nine interrupted for minor complications. The median duration of irrigation in the whole group is 257 days (range, 1 to 2669 days): 32 patients have been irrigating from one to five years, and 9 patients for more than 5 years. Based on these results, we recommend irrigation as standard rehabilitative treatment for elderly patients.