Frequent anti-V-region immune response to mouse B72.3 monoclonal antibody

Phage display-derived human antibodies in clinical development and therapy

Over the last 3 decades, monoclonal antibodies have become the most important class of therapeutic biologicals on the market. Development of therapeutic antibodies was accelerated by recombinant DNA technologies, which allowed the humanization of murine monoclonal antibodies to make them more similar to those of the human body and suitable for a broad range of chronic diseases like cancer and autoimmune diseases. In the early 1990s in vitro antibody selection technologies were developed that enabled the discovery of “fully” human antibodies with potentially superior clinical efficacy and lowest immunogenicity.

Antibody phage display is the first and most widely used of the in vitro selection technologies. It has proven to be a robust, versatile platform technology for the discovery of human antibodies and a powerful engineering tool to improve antibody properties. As of the beginning of 2016, 6 human antibodies discovered or further developed by phage display were approved for therapy. In 2002, adalimumab (Humira®) became the first phage display-derived antibody granted a marketing approval. Humira® was also the first approved human antibody, and it is currently the best-selling antibody drug on the market. Numerous phage display-derived antibodies are currently under advanced clinical investigation, and, despite the availability of other technologies such as human antibody-producing transgenic mice, phage display has not lost its importance for the discovery and engineering of therapeutic antibodies.

Here, we provide a comprehensive overview about phage display-derived antibodies that are approved for therapy or in clinical development. A selection of these antibodies is described in more detail to demonstrate different aspects of the phage display technology and its development over the last 25 years.

Lack of Efficacy of Two Consecutive Treatments of Radioimmunotherapy With131I-cG250 in Patients With Metastasized Clear Cell Renal Cell Carcinoma

Purpose

A previous activity dose-escalation study using131I-labeled chimeric monoclonal antibody cG250 in patients with progressive metastatic renal cell carcinoma (RCC) resulted in occasional therapeutic responses. The present study was designed to determine the safety and therapeutic efficacy of two sequential high-dose treatments with131I-cG250.

Patients and Methods

Patients (n = 29) with progressive metastatic RCC received a low dose of131I-cG250 for assessment of preferential targeting of metastatic lesions, followed by the first radioimmunotherapy (RIT) with 2220 MBq/m2131I-cG250 (n = 27) 1 week later. If no grade 4 hematologic toxicity was observed, a second low-dose131I-cG250 (n = 20) was given 3 months later. When blood clearance was not accelerated, a second RIT of131I-cG250 was administered at an activity-dose of 1110 MBq/m2(n = 3) or 1665 MBq/m2(n = 16). Patients were monitored weekly for toxicity, and tumor size was evaluated by computed tomography once every 3 months intervals.

Results

The maximum-tolerated dose (MTD) of the second RIT was 1,665 MBq/m2because of dose-limiting hematological toxicity. Based on an intention-to-treat analysis, after two RIT treatments, the disease stabilized in five of 29 patients, whereas it remained progressive in 14 of 29 patients. Two patients received no RIT, and eight of 29 received only one131I-cG250 RIT because of grade 4 hematologic toxicity, formation of human antichimeric antibodies, or disease progression.

Conclusion

In patients with progressive end-stage RCC, the MTD of the second treatment was 75% of the MTD of the first RIT. In the majority of patients, two cycles of131I-cG250 could be safely administered without severe toxicity. No objective responses were observed, but occasionally two RIT doses resulted in stabilization of previously progressive disease.

Randomised trial of basiliximab versus placebo for control of acute cellular rejection in renal allograft recipients. CHIB 201 International Study Group

BACKGROUND

Currently available immunosuppressive regimens for cadaver-kidney recipients are far from ideal because acute-rejection episodes occur in about 30% to 50% of these patients. In the phase III study described here we assessed the ability of basiliximab, a chimeric interleukin (IL)-2 receptor monoclonal antibody, to prevent acute-rejection episodes in renal allograft recipients.

METHODS

380 adult recipients of a primary cadaveric kidney transplant were randomly allocated, in this double-blind trial, to receive a 20 mg infusion of basiliximab on day 0 (day of surgery) and on day 4, to provide IL-2-receptor suppression for 4-6 weeks (n=193), or to receive placebo (n=187). Both groups received baseline dual immunosuppressive therapy with cyclosporin and steroids throughout the study. The primary outcome measure was incidence of acute-rejection episodes during the 6 months after transplantation. Safety and tolerability were monitored over the 12 months of the study.

FINDINGS

376 patients were eligible for intention-to-treat analysis (basiliximab, n=190; placebo, n=186). No significant differences in patient characteristics were apparent. The incidence of biopsy-confirmed acute rejection 6 months after transplantation was 51 (29.8%) of 171 in the basiliximab group compared with 73 (44.0%) of 166 in the placebo group (32% reduction; 14.2% difference [95% Kaplan-Meier CIs 3% to 24%], p=0.012). The incidence of steroid-resistant first rejection episodes that required antibody therapy was significantly lower in the basiliximab group (10% vs 23.1%, 13.1% difference [5.4% to 20.8%], p<0.001). At weeks 2 and 4 post-transplantation, the mean daily dose of steroids was significantly higher in the placebo group (p<0.001 with one-way analysis of variance). The incidence of graft loss at 12 months post-transplantation was 23 (12.1%) of 190 in the basiliximab group and 25 (13.4%) of 186 in the placebo group (1.3% difference [-5% to 9%], p=0.591). The incidence of infection and other adverse events was similar in the two treatment groups. The acute tolerability of basiliximab was excellent, with no evidence of cytokine-release syndrome. 14 deaths (basiliximab n=9; placebo n=5; -2.0% difference [-6% to 2%], p=0.293) occurred during the 12-month study and a further three deaths (basiliximab n=1; placebo n=2) occurred within the 380-day cut-off period. One post-transplantation lymphoproliferative disorder was recorded in each group.

INTERPRETATION

Prophylaxis with 40 mg basiliximab reduces the incidence of acute rejection episodes significantly, with no clinically relevant safety or tolerability concerns.

Granulocyte/macrophage-colony-stimulating factor augments the induction of antibodies, especially anti-idiotypic antibodies, to therapeutic monoclonal antibodies

A group of 86 patients with advanced colorectal carcinoma were treated with the mouse (m) (IgG2A) or chimeric (c) monoclonal antibody (mAb) 17-1A. Prior to therapy, no patient had detectable levels of antibodies to mAb17-1A. All mmAb17-1A-treated patients (n = 76) developed antibodies against both idiotypic and isotypic determinants. Addition of granulocyte/macrophage-colony-stimulating factor (GM-CSF) to mmAb17-1A significantly enhanced the induction of anti-idiotypic (ab2) as well as anti-isotypic antibodies. Of the mmAb17-1A-treated patients, 16 developed type I allergic reactions. These patients had significantly higher concentrations of anti-(mouse Ig) antibodies than patients without type I reactions. Of these 16 patients, 5 had received mmAb17-1A alone; they constituted 9% of this group (5/56). The remaining 11 patients had been given mmAb17-1A together with GM-CSF, and represented 55% of this treatment group (11/20). The difference was statistically significant (P < 0.001). Of 10 patients, 9 (90%) treated with cmAb17-1A and GM-CSF developed ab2. The ab2 concentration in this patient group was significantly lower compared to those treated with mmAb-17A. Anti-(mouse Ig) antibodies caused clinical symptoms requiring therapeutic intervention in fewer than 10% of the patients treated with mmAb17-1A alone. With the addition of GM-CSF, the antibody concentration as well as the frequency of allergic side-effects calling for medical action increased significantly. Significantly more patients with a high ab2 concentration (at least 15 micrograms/ml) 1 month after completion of mAb therapy responded to mAb treatment as compared to those with a low ab2 concentration (P < 0.05). Moreover, patients with a high ab2 concentration (at least 15 micrograms/ml) had a median survival time of 15 months while those with a lower concentration survived for a median time of 9 months (P = 0.01).

Antiidiotypic antibodies in ovarian cancer patients treated with the monoclonal antibody B72.3

Immunotherapy with monoclonal antibodies has become a hopeful approach to the adjuvant therapy of cancer patients. Recently, formation of antiidiotypic antibodies (Ab2) has been demonstrated in ovarian cancer patients after immunization with F(ab')2 fragments of the monoclonal antibody OC 125 (MAb OC 125). Preliminary results suggested that patients with high Ab2 serum concentrations had better survival rates compared to those where low or no Ab2 serum levels were detected. Beginning in 1992, 23 patients with advanced ovarian adenocarcinomas have been treated with repeated intravenous applications of the MAb B72.3, which is directed against the ovarian carcinoma associated antigen TAG-72. Five of them had been pretreated with several F(ab')2 MAb OC 125 infusions. Blood sample analysis revealed a remarkable antiidiotypic antibody (Ab2) response in 14 patients, with five patients developing high serum levels > 1000 U/ml. Ab2 serum concentrations increased with increasing number of Mab B72.3 applications. In terms of serum levels, corresponding antiidiotypic antibody responses in patients who received both the F(ab')2 MAb OC 125 and the MAb B72.3 differed considerably. We conclude that the use of MAb B72.3 may be an additional beneficial approach to the immunological therapy of ovarian cancer. Subsequent MAb B72.3 application after failure of the F(ab')2 MAb OC 125 may induce appreciable Ab2 serum concentrations and vice versa.

Minor human antibody response to a mouse and chimeric monoclonal antibody after a single i.v. infusion in ovarian carcinoma patients: a comparison of five assays

The human anti-(mouse Ig) antibody (HAMA) response was measured in serum of 52 patients suspected of having ovarian carcinoma who had received an i.v. injection of either the murine monoclonal antibody (mAb) OV-TL 3 F(ab')2 (n = 28, 1 mg) or the chimeric mouse/human mAb MOv18 (cMOv18; n = 24, 3 mg). Serum samples were taken before injection and 2-3 and 6-14 weeks after administration. A double-antigen or bridging assay was developed to detect responses against both murine as well as chimeric antibodies. In addition, an indirect enzyme-linked immunosorbent assay (ELISA) as well as three commercially available assays were used to study antibody response against the murine antibody OV-TL 3. With both the double-antigen (bridging) assay and the indirect ELISA 1 of the 28 patients (4%) injected with murine OV-TL 3 F(ab')2 showed a HAMA reaction 6 weeks after injection, which was demonstrated to be a mixed anti-isotypic and anti-idiotypic response. None of the 24 patients injected with the chimeric MOv18 showed an anti-chimeric antibody response. The various commercially available assays demonstrated conflicting results. The double-antigen- or bridging assay is a reliable method to detect anti-murine and anti-chimeric antibodies. The assay can be easily adapted for use with human antibodies. The immunogenicity of OV-TL 3 F(ab')2 and cMOv18 in patients is low, making both antibodies candidates for immunotherapy.

Clinical pharmacology and tissue disposition studies of 131I-labeled anticolorectal carcinoma human monoclonal antibody LiCO 16.88

Antibody LiCO 16.88 is a human IgM recognizing a 30- to 45-kDa intracytoplasmic antigen present in human adenocarcinoma cells. An 8-mg sample of antibody labeled with 5 mCi 131I was co-administered i.v. with 120 mg (three patients), 240 mg (three patients) or 480 mg (four patients) unlabeled antibody as a 4-h infusion. The plasma half-life was 24 +/- 1.2 h and the immediate apparent volume of distribution was 5.2 +/- 0.2 l at the 28-mg dose level. The plasma half-lives and the cumulative urinary excretion of radiolabel did not seem to vary significantly with increasing doses of unlabeled antibody. However, both the volume of distribution and the clearance rate from plasma increased significantly with increasing antibody dose. Uptake of antibody into tumor tissues obtained during laparotomy 8-9 days after administration varied between 0.00002% ID/g and 0.00127% ID/g. In five of seven patients, the tumor content of antibody was higher than that in adjacent normal tissue. Tumor-to-normal tissue ratios ranged from 0.8 to 10 (mean = 3.8 +/- 1.0). In general, the higher radioactivity(cpm)/g tumor was confirmed by both immunoperoxidase and autoradiography. Antibody 16.88 localizes in tumors after administration and may be considered for use in radioimmunotherapy trials.

Generation and characterization of a mouse/human chimeric antibody directed against extracellular matrix protein tenascin

The murine anti-tenascin monoclonal antibody 81C6, following iodination, has been shown to be an efficient localizing and therapeutic agent in both subcutaneous and intracranial human glioma xenograft models in athymic mice and rats. Similarly, effective monoclonal antibody 81C6 localization has been demonstrated in glioma patients, and Phase I trials with the intact murine IgG2b kappa molecule are currently in progress. In order to maximize the potential for repeated administration by minimizing murine Fc-mediated immunogenicity and reducing Fc-mediated immune effects, we created murine 81C6 variable region/human IgG2 chimeric monoclonal antibodies by the molecular cloning of the variable region genes of mouse 81C6 and their genetic linkage to human constant region exons. The resulting chimeric constructs were introduced into SP2/0 cells, and stable transfectomas were selected by G418 and mycophenolic acid resistance. The resistant clones were screened for anti-tenascin activity on tenascin-coated plates by enzyme-linked immunosorbent assay. The N-terminal amino acid sequence of both heavy and light chains of the purified chimeric 81C6 antibody matched exactly with that of the native mouse 81C6 as well as with that deduced from the nucleotide sequence. The production level of chimeric 81C6 (13.9 mg/ml) from ascites in the highest expressing transfectoma was much higher than that of native mouse 81C6 (2.5 mg/ml). The chimeric antibody showed the same specificity and equivalent affinity for human intact tenascin or tenascin-expressing cells as the native mouse 81C6 antibody. Direct comparison of radioiodinated chimeric and radioiodinated mouse 81C6 biodistribution in subcutaneous and intracranial xenograft-bearing mice showed higher tumor-to-normal tissue ratios for chimeric 81C6 as compared with native mouse 81C6. The improved localizing and clearance characteristics of chimeric 81C6 in xenograft model systems suggests that chimeric 81C6 would be an improved reagent for intracompartmental therapy of tenascin-expressing tumors in the human central nervous system.

Mouse/human chimeric Me1-14 antibody: genomic cloning of the variable region genes, linkage to human constant region genes, expression, and characterization

Murine monoclonal antibody Me1-14, which recognizes an epitope on chondroitin proteoglycan sulfate expressed in malignant glioma and melanoma, has been used for radioimmunolocalization and therapy both in animal models and in patients. Here, we report the generation, characterization, and in vivo biodistribution of mouse/human chimeric Me1-14. Rearranged immunoglobulin genes from the Me1-14 hybridoma were identified by Southern blot analysis. Putative rearranged light- and heavy-chain genes were cloned from Lambda-ZapII Me1-14 genomic libraries and sequenced for nucleotide analysis. One of the putative heavy-chain Eco RI fragments (3.5 kb) had all the features of an intact variable region, including a functional leader sequence, in-frame V-D and D-J junctions, and cysteines 22 and 92. The deduced amino acid sequence from the heavy-chain variable region gene showed considerable homology with the invariant protein sequence of the mouse heavy-chain subgroup IIIB. Like the heavy-chain gene, one of the putative rearranged kappa-chain Hind III fragments (4 kb) had all of the characteristics of the functional variable region, and the deduced amino acid sequence showed homology to the invariant sequence of kappa-chain group V. The variable region genes for heavy- and light-chains were linked to human constant region exons in the expression vectors at the unique sites and cotransfected into mouse SP2/0 cells. The production level of chimeric Me1-14 from ascites in the highest expressing transfectoma was 1.8 mg/ml. The chimeric Me1-14 antibody exhibited the same specificity and similar affinity as that of parent Me1-14. Direct comparison of radioiodinated chimeric and murine Me1-14 in paired-label biodistribution analysis in subcutaneous xenograft-bearing mice showed higher tumor-to-normal organ ratios for chimeric Me1-14 IgG2, suggesting that this chimeric Me1-14 may be potentially useful in vivo for diagnostic and therapeutic purposes in patients.

Construction and initial characterization of a mouse-human chimeric anti-TNF antibody

Tumor necrosis factor-alpha (TNF) has been implicated in the pathogenesis of a variety of human diseases including septic shock, cachexia, graft-versus-host disease and several autoimmune diseases. Monoclonal antibodies directed against TNF provide an attractive mode of therapeutic intervention in these diseases. We have generated a murine monoclonal antibody (A2) with high affinity and specificity for recombinant and natural human TNF. To increase its therapeutic usefulness, we used genetic engineering techniques to replace the murine constant regions with human counterparts while retaining the murine antigen binding regions. The resulting mouse-human chimeric antibody should have reduced immunogenicity and improved pharmacokinetics in humans. Molecular analysis of light chain genomic clones derived from the murine hybridoma suggests that two different alleles of the same variable region gene have rearranged independently and coexist in the same hybridoma cell. The chimeric A2 antibody (cA2) exhibits better binding and neutralizing characteristics than the murine A2 which was shown to contain a mixture of two kappa light chains. The properties of cA2 suggest that it will have advantages over existing murine anti-TNF antibodies for clinical use.

Use of a chimeric monoclonal anti-CD4 antibody in patients with refractory rheumatoid arthritis

OBJECTIVES

To evaluate the safety, immunogenicity, and biologic effects of chimeric monoclonal anti-CD4 (cM-T412) in patients with refractory rheumatoid arthritis (RA), and to obtain preliminary data on the clinical response to this treatment.

METHODS

Twenty-five patients with active refractory RA were treated with incremental doses (10 to 700 mg) of cM-T412 in an open-label, escalating-dose phase I trial.

RESULTS

Infusion with cM-T412 was followed by an immediate, rapid decline in CD4+ T cells. The level of circulating CD4+ T cells remained depressed in most patients even at 6 months posttreatment. Following antibody infusion, proliferative responses of peripheral blood lymphocytes to mitogens and antigens were determined; mitogen and antigen responses were decreased compared with pretreatment responses. Mitogen responses tended to return to baseline values more rapidly than did responses to antigen. Adverse events included fever (19 patients), which was associated with myalgias, malaise, and asymptomatic hypotension; these symptoms were self-limited and appeared to correlate with transient elevations in interleukin-6. No significant human antibody response to the cM-T412 variable region was detected; only 2 patients developed transiently low levels of antibodies reactive with cM-T412. Significant clinical improvement, defined as > or = 50% decrease in tender joint counts compared with baseline, was noted in 43% of patients at 5 weeks and 33% at 6 months following cM-T412 infusion.

CONCLUSIONS

Treatment of refractory RA with cM-T412 appears to be safe and is associated with sustained decreases in circulating CD4+ T cell counts and depressed in vitro T cell responses. No significant human antichimeric antibody response was detected. Nonblinded assessment of clinical end points suggests that treatment with cM-T412 may have beneficial effects in these patients with refractory RA. A double-blind clinical trial is warranted to determine its clinical efficacy in treating RA.

Engineering antibodies for therapy

Success in the generation of an antibody-based therapeutic requires careful consideration of the binding site, to achieve specificity and high affinity; of the effector, to produce the desired therapeutic effect; of the means of attachment of the effector to the binding site; production of the end product; and the response made by the patient to the administered compound. Each of these areas is receiving attention by antibody-engineering techniques. The number of potentially useful monoclonal antibodies developed over the last 10 years, and currently in clinical trials or preregistration, is now being increased by these engineered newcomers. It will be interesting to see over the next few years how many of these antibodies, and of which kind, emerge as products.