First-in-human study of the safety, tolerability, pharmacokinetics, and pharmacodynamics of ALPN-101, a dual CD28/ICOS antagonist, in healthy adult subjects

ALPN-101 (ICOSL vIgD-Fc) is an Fc fusion protein of a human inducible T cell costimulatory ligand (ICOSL) variant immunoglobulin domain (vIgD) designed to inhibit the cluster of differentiation 28 (CD28) and inducible T cell costimulator (ICOS) pathways simultaneously. A first-in-human study evaluated the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of ALPN-101 in healthy adult subjects. ALPN-101 was generally well-tolerated with no evidence of cytokine release, clinically significant immunogenicity, or severe adverse events following single subcutaneous (SC) doses up to 3 mg/kg or single intravenous (IV) doses up to 10 mg/kg or up to 4 weekly IV doses of up to 1 mg/kg. ALPN-101 exhibited a dose-dependent increase in exposure with an estimated terminal half-life of 4.3-8.6 days and SC bioavailability of 60.6% at 3 mg/kg. Minimal to modest accumulation in exposure was observed with repeated IV dosing. ALPN-101 resulted in a dose-dependent increase in maximum target saturation and duration of high-level target saturation. Consistent with its mechanism of action, ALPN-101 inhibited cytokine production in whole blood stimulated by Staphylococcus aureus enterotoxin B ex vivo, as well as antibody responses to keyhole limpet hemocyanin immunization, reflecting immunomodulatory effects upon T cell and T-dependent B cell responses, respectively. In conclusion, ALPN-101 was well-tolerated in healthy subjects with dose-dependent PK and PD consistent with the known biology of the CD28 and ICOS costimulatory pathways. Further clinical development of ALPN-101 in inflammatory and/or autoimmune diseases is therefore warranted.

M281, an Anti-FcRn Antibody: Pharmacodynamics, Pharmacokinetics, and Safety Across the Full Range of IgG Reduction in a First-in-Human Study

M281 is a fully human, anti-neonatal Fc receptor (FcRn) antibody that inhibits FcRn-mediated immunoglobulin G (IgG) recycling to decrease pathogenic IgG while preserving IgG production. A randomized, double-blind, placebo-controlled, first-in-human study with 50 normal healthy volunteers was designed to probe safety and the physiological maximum for reduction of IgG. Intravenous infusion of single ascending doses up to 60 mg/kg induced dose-dependent serum IgG reductions, which were similar across all IgG subclasses. Multiple weekly doses of 15 or 30 mg/kg achieved mean IgG reductions of ≈85% from baseline and maintained IgG reductions ≥75% from baseline for up to 24 days. M281 was well tolerated, with no serious or severe adverse events (AEs), few moderate AEs, and a low incidence of infection-related AEs similar to placebo treatment. The tolerability and consistency of M281 pharmacokinetics and pharmacodynamics support further evaluation of M281 in diseases mediated by pathogenic IgG.

Efficacy and safety of abatacept in lupus nephritis: a twelve-month, randomized, double-blind study

OBJECTIVE

To compare the efficacy and safety of intravenous (IV) abatacept, a selective T cell costimulation modulator, versus placebo for the treatment of active class III or IV lupus nephritis, when used on a background of mycophenolate mofetil and glucocorticoids.

METHODS

This was a 12-month, randomized, phase II/III, multicenter, international, double-blind study. A total of 298 patients were treated in 1 of 3 IV treatment arms: placebo, abatacept at the standard weight-tiered dose (approximating 10 mg/kg), or abatacept at 30 mg/kg for 3 months, followed by the standard weight-tiered dose (abatacept 30/10). The primary end point, time to confirmed complete response, was a composite measure that required maintenance of glomerular filtration rate, minimal proteinuria, and inactive urinary sediment over the 52-week treatment period.

RESULTS

There were no differences among treatment arms in the time to confirmed complete response or in the proportion of subjects with confirmed complete response following 52 weeks of treatment. Treatment with abatacept was associated with greater improvements from baseline in anti-double-stranded DNA antibody, C3, and C4 levels. Among 122 patients with nephrotic-range proteinuria, treatment with abatacept resulted in an ∼20-30% greater reduction in mean urinary protein-to-creatinine ratio compared with placebo. Abatacept was well tolerated; rates of deaths, serious adverse events, and serious infections were similar across treatment arms. Gastroenteritis and herpes zoster occurred more frequently with abatacept treatment.

CONCLUSION

Although the primary end point was not met, abatacept showed evidence of biologic activity and was well tolerated in patients with active class III or IV lupus nephritis.

Peginterferon Lambda-1a, a New Therapeutic for Hepatitis C Infection, from Bench to Clinic

Chronic infection with hepatitis C virus (HCV) is estimated to affect approximately 3% of the world's population and cause 350,000 deaths each year. For a number of years, the standard of care has been combination therapy with recombinant alfa interferons-originally as native proteins but more recently as polyethyleneglycol-modified derivatives-and ribavirin, with the recent addition of an NS3 protease inhibitor for HCV genotype 1. However, therapeutic alfa interferons are associated with a significant burden of treatment-limiting adverse events, including musculoskeletal and influenza-like symptoms, hematologic cytopenias, autoimmune disease, fatigue, and other neurologic events. In 2003, a team at ZymoGenetics (now a fully owned subsidiary of Bristol-Myers Squibb) and a second, independent group simultaneously identified a new class of interferons-the type III lambda interferons-with near-identical activity to the type I alfa interferons in hepatocytes but with an unrelated and less ubiquitous receptor. Subsequent evaluation of the type III interferon system demonstrated antiviral activity against HCV in vitro with limited activity in peripheral blood mononuclear cells and other nonhepatocyte cell types, supporting its development as a potentially better-tolerated therapy for viral hepatitis. Peginterferon lambda-1a (Lambda) is an investigational type III therapeutic agent originally developed at ZymoGenetics that is currently in Phase 3 studies for the treatment of HCV. In this review, we describe the selection of the Lambda molecule and its preclinical and early clinical development, and how the resulting data have helped to establish the differentiated safety profile for Lambda-with fewer influenza-like and musculoskeletal symptoms and less hematologic toxicity than the alfa interferons-that was seen in later studies.

Comparison of alternative primary outcome measures for use in lupus nephritis clinical trials

OBJECTIVE

Clinical trials of therapies for lupus nephritis have used many different primary outcome measures, ranging from complete response to time to end-stage renal disease. The objective of this study was to compare several possible outcome measures, using data from a large, multicenter trial of abatacept in lupus nephritis, to gain insight into which outcome measure, if any, was best able to discern differences among treatment groups.

METHODS

Study patients received either abatacept or placebo, on a background of mycophenolate mofetil and glucocorticoids. Using data from this trial, the following primary outcome measures at 24 and 52 weeks were compared: complete response rate, major clinical response rate, total response rate (complete plus partial response), improvement in proteinuria, improvement in estimated glomerular filtration rate, and frequency of treatment failure. Time to complete response was also evaluated.

RESULTS

Complete response rate, major clinical response rate, and time to complete response were the measures that best discriminated between the abatacept groups and placebo, and the sensitivities of these 3 measures were comparable. For these measures, sample sizes of 50 patients would have been sufficient to demonstrate a statistically significant difference between treatment and control at 52 weeks. Each of the other measures also discriminated between treatment and control, but much larger group sizes would have been required to determine statistical significance.

CONCLUSION

The choice of primary outcome measure can substantially influence the ability to detect therapeutic benefit in lupus nephritis trials. This study suggests that complete response rate, major clinical response rate at 52 weeks, and time to complete response may be the most sensitive outcome measures for detecting differences among therapeutic regimens.

Abatacept for lupus nephritis: alternative definitions of complete response support conflicting conclusions

OBJECTIVE

Recent clinical trials in lupus nephritis have all used different criteria to assess complete response. The objective of this analysis was to compare several previously proposed criteria, using the same data set from a large trial of abatacept in lupus nephritis (IM101075). In so doing, we sought to determine which criteria are most sensitive to differences among treatment groups and to further examine the potential of abatacept in lupus nephritis.

METHODS

Patients in the IM101075 trial received abatacept at 1 of 2 different dose regimens or placebo, both on a background of mycophenolate mofetil and corticosteroids. Using data from this trial, we assessed rates of complete response at 12 months according to 5 sets of criteria, from 1) the trial protocol, 2) the Aspreva Lupus Management Study (ALMS) trial of mycophenolate mofetil, 3) the Lupus Nephritis Assessment with Rituximab (LUNAR) trial of rituximab, 4) an ongoing National Institutes of Health trial of abatacept (Abatacept and Cyclophosphamide Combination: Efficacy and Safety Study [ACCESS]), and 5) published recommendations of the American College of Rheumatology.

RESULTS

According to the complete response definition from the IM101075 study protocol, there was no difference among treatment groups in the IM101075 study. In contrast, according to the ALMS, LUNAR, and ACCESS criteria, rates of complete response among patients in the IM101075 study were higher in both treatment groups relative to control. The largest differences were obtained with use of the LUNAR criteria (complete response rate of 6% in the control group, compared to 22% and 24% in the 2 abatacept groups).

CONCLUSION

The choice of definition of complete response can determine whether a lupus nephritis trial is interpreted as a success or a failure. The results of this analysis provide an evidence-based rationale for choosing among alternative definitions and offer a strong rationale for conducting further studies of abatacept in lupus nephritis.

Rofecoxib

Rofecoxib (Vioxx, Merck & Co., Inc.) is a new orally-effective non-steroidal anti-inflammatory drug (NSAID) approved for treatment of acute pain, fever, primary dysmenorrhea and pain and inflammation in osteoarthritis (OA). It is also being evaluated for treatment of rheumatoid arthritis and adenomatous polyps of the colon. Rofecoxib is a specific inhibitor of cyclooxygenase-2 (COX-2), thereby inhibiting prostanoid synthesis in cells that express COX-2, including inflammatory cells. As cells in the gastrointestinal (GI) tract principally express COX-1, a different isoform of cyclooxygenase, it is predicted that rofecoxib will have less GI toxicity than other less selective NSAIDs. In clinical trials, rofecoxib was found to be as effective as other NSAIDs for management of pain and inflammation. In trials that compare rofecoxib with ibuprofen, diclofenac and indomethacin, less GI toxicity has been observed, as assayed by a decrease in lesions visible on endoscopy, by GI blood loss and, in a meta-analysis, by frequency of serious adverse GI events. The presence of COX-2 in cells other than inflammatory cells results in side effects common among NSAIDs, including peripheral oedema and hypertension. These side effects are dose-dependent. Rofecoxib, together with other branded NSAIDs, are relatively expensive, which has led to concern regarding costs versus benefits. There is also concern regarding potential risks associated with the use of rofecoxib by populations that would otherwise not tolerate NSAIDs.

Pharmacology and pharmacokinetics of methotrexate in rheumatic disease. Practical issues in treatment and design

Methotrexate (MTX) is among the most effective drugs for treatment of rheumatoid arthritis and has been proven valuable in the treatment of multiple other disorders of immune regulation. MTX has been administered at a wide range of doses and dose intervals, in conjunction with multiple other drugs, and in patients with a broad range of concomitant disorders. To design a safe and effective MTX treatment plan for an individual patient, the provider must have knowledge of the pharmacology and drug interactions of this effective but potentially dangerous medication. The first section of the article reviews MTX structure, pharmacology pharmacokinetics, and mechanisms of action in rheumatic disease. The second section examines factors that can be used to increase MTX efficacy and decrease toxicity.

An unbiased analysis of V(H)-D-J(H) sequences from B-1a, B-1b, and conventional B cells

Previous studies conclude that the repertoire of B-1a (CD5+ B) cells is highly restricted. Studies here, which use FACS sorting and single-cell PCR methodology to develop an unbiased representation of the IgH repertoires of B-1a, B-1b, and conventional B cells from the peritoneal cavity, demonstrate that the B-1a cell repertoire is more diverse than previously thought. Furthermore, adult B-1a cells have significantly fewer noncoded nucleotide (N) insertions than conventional B cells. However, B-1a cells are not defined by the absence of these regions, since such insertions are present in two-thirds of B-1a cell transcripts. All three B cell populations use a wide spectrum of V(H), D, and J(H) elements and display considerable diversity in complementarity-determining region 3 (CDR3). However, characteristic differences in the repertoires of all three B cell populations also exist, suggesting different selective and/or developmental forces act to shape each repertoire.

An unbiased analysis of V(H)-D-J(H) sequences from B-1a, B-1b, and conventional B cells

Previous studies conclude that the repertoire of B-1a (CD5+ B) cells is highly restricted. Studies here, which use FACS sorting and single-cell PCR methodology to develop an unbiased representation of the IgH repertoires of B-1a, B-1b, and conventional B cells from the peritoneal cavity, demonstrate that the B-1a cell repertoire is more diverse than previously thought. Furthermore, adult B-1a cells have significantly fewer noncoded nucleotide (N) insertions than conventional B cells. However, B-1a cells are not defined by the absence of these regions, since such insertions are present in two-thirds of B-1a cell transcripts. All three B cell populations use a wide spectrum of V(H), D, and J(H) elements and display considerable diversity in complementarity-determining region 3 (CDR3). However, characteristic differences in the repertoires of all three B cell populations also exist, suggesting different selective and/or developmental forces act to shape each repertoire.

The structural basis of germline-encoded VH3 immunoglobulin binding to staphylococcal protein A

The ability of human VH3 immunoglobulins (Ig) to bind to staphylococcal protein A (SPA) via their Fab region is analogous to the binding of bacterial superantigens to T cell receptors. The present report establishes the structural basis for the interaction of SPA and VH3 Ig. We have studied a panel of 27 human monoclonal IgM that were derived from fetal B lymphocytes. As such, these IgM were expected to be encoded by unmutated germline genes. Binding to SPA in ELISA occurred with 15 of 15 VH3 IgM, but none of 12 IgM from the VH1, VH4, VH5, or VH6 families. The VH sequences of the 27 IgM were derived from 20 distinct VH elements, including 11 from the VH3 family. Use of D, JH, and CL genes was similar among VH3 and non-VH3 IgM. A comparison of the corresponding VH protein sequences, and those of previously studied IgM, identified a probable site for SPA binding that includes VH3 residues in framework region 3 (FR3), and perhaps FR1 and 3' complementary determining region 2. The results thus demonstrate that among human IgM, specificity for SPA is encoded by at least 11 different VH3 germline genes. Furthermore, like the T cell superantigens, SPA likely binds to residues in the VH framework region, outside the classical antigen-binding site of the hypervariable loops.

Emerging human B cell repertoire. Influence of developmental stage and interindividual variation

In B cell precursors developing in fetal lymphopoietic tissue, the selection of VH, DH, and JH gene segments for initial H chain gene assembly is biased. The present study was designed to determine whether these biases persist in fully developed human fetal B cells and to examine specificities encoded by the favored elements. B cells were prepared from two sites representing different stages of development, i.e., fetal liver as a source of cells newly generated in that lymphopoietic environment and fetal spleen as a source of more mature cells, potentially subject to selective environmental factors. The expressed repertoires were sampled by two methods. EBV transformation so binding and structure could be examined simultaneously and generation of cDNA from individual, sorted, unstimulated B cells. We found that mature B cells in liver and secondary lymphoid tissue exhibit the same degree of bias in VH use we previously reported in lymphopoietic tissue of the same gestational age. However, the pattern of DH and JH use more nearly resembled that of the adult, suggesting that some constraints imposed by the rearrangement process are normalized rapidly. Sequences recovered from EBV-transformed clones were not distinguishable from transcripts recovered from single cells by direct amplification. Among antibodies expressed by the EBV clones, binding to self-Ag was common, binding profiles varied, and, in contrast to mice, there was little relationship between specificity and VH element. Interestingly, the two individuals studied differed in the VH element most commonly used. One resembled previously studied fetal repertoires in that VH56p1 encoded about 20% of expressed antibodies, whereas the other did not express VH56p1 and used VH26 in 25% of expressed antibodies. This was found to reflect a lack of the genomic VH56p1 allele, suggesting that genetic variation at the VH locus may significantly influence the emerging human antibody repertoire.

Emerging human B cell repertoire. Influence of developmental stage and interindividual variation

In B cell precursors developing in fetal lymphopoietic tissue, the selection of VH, DH, and JH gene segments for initial H chain gene assembly is biased. The present study was designed to determine whether these biases persist in fully developed human fetal B cells and to examine specificities encoded by the favored elements. B cells were prepared from two sites representing different stages of development, i.e., fetal liver as a source of cells newly generated in that lymphopoietic environment and fetal spleen as a source of more mature cells, potentially subject to selective environmental factors. The expressed repertoires were sampled by two methods. EBV transformation so binding and structure could be examined simultaneously and generation of cDNA from individual, sorted, unstimulated B cells. We found that mature B cells in liver and secondary lymphoid tissue exhibit the same degree of bias in VH use we previously reported in lymphopoietic tissue of the same gestational age. However, the pattern of DH and JH use more nearly resembled that of the adult, suggesting that some constraints imposed by the rearrangement process are normalized rapidly. Sequences recovered from EBV-transformed clones were not distinguishable from transcripts recovered from single cells by direct amplification. Among antibodies expressed by the EBV clones, binding to self-Ag was common, binding profiles varied, and, in contrast to mice, there was little relationship between specificity and VH element. Interestingly, the two individuals studied differed in the VH element most commonly used. One resembled previously studied fetal repertoires in that VH56p1 encoded about 20% of expressed antibodies, whereas the other did not express VH56p1 and used VH26 in 25% of expressed antibodies. This was found to reflect a lack of the genomic VH56p1 allele, suggesting that genetic variation at the VH locus may significantly influence the emerging human antibody repertoire.

Sequence analysis and idiotypic relationships of BEG-2, a human fetal antibody reactive with DNA

Monoclonal antibody (mAb) BEG-2 is a dsDNA binding IgM lambda derived from a 12-week human fetus. Two binding site idiotypes (BEG-2 Id alpha and BEG-2 Id beta) have been defined with the use of polyclonal rabbit anti-idiotypic anti-serum. BEG-2 Id alpha is located on the lambda light chain and has been described previously. The BEG-2 Id beta is present on the mu heavy chain. By means of a direct binding ELISA, BEG-2 Id beta has been identified on EBV-derived mAbs from human fetal liver or spleen (5%), human cord blood (2.7%) and adult peripheral blood (1%). In addition, the Id is present on 8.5% of adult spleen-derived hybridoma antibodies and 6% of RA synovium-derived hybridoma antibodies. In all populations the presence of the Id is strongly associated with binding to DNA and other polyanions. Competition assays indicated that the Id was located at or near the antigen-binding site on these molecules. To explore the structural basis of this binding, a major part of the BEG-2 heavy chain was sequenced and found to be encoded by a member of the VH4 family joined to a variant of JH5 by a very short Diversity or N region. Of the BEG-2 Id beta positive mAbs for which the VH family has been determined, five are encoded by VH4 and two are encoded by VH6, but none is encoded by other families. Thus, the BEG-2 Id beta identifies a set of polyreactive antibodies that are common in fetal life, persist into adulthood and are encoded by VH6 and, a subset of VH4 genes.

Autoantibodies and the fetal antibody repertoire

Developing fetal B cells preferentially rearrange a restricted subset of the encoded antibody gene segments. There are striking structural similarities between elements expressed early in man and in mouse, most evident on comparison of murine VH elements from the VH7183 family to human VH elements of the VH3 family. The similarity is pronounced in two framework regions which together encode a possible binding site that is distinct from the classical antigen-combining site. By comparing all known human and murine VH gene sequences, we have demonstrated that these regions have been conserved in a family-specific manner throughout the mammalian radiation. The "non-conserved" spacer of the recombinase recognition signal is also highly conserved in a family-specific manner, suggesting a mechanism by which the expression of family-dependent features may be regulated. The evidence that such features contribute to the high incidence of self- and poly-specificity in the fetal antibody repertoire is reviewed.

Structure and evolution of mammalian VH families

Antibodies are encoded by a limited number of germline gene segments that undergo somatic diversification through rearrangement and mutation. Because these mutation processes are efficient, it is widely believed that there is little environmental selection pressure for the maintenance of specific antibody gene sequences. We have performed pairwise comparisons of known germline (as opposed to somatically generated) antibody VH elements with the hope of identifying conserved structural features common to sets of VH gene segments. These studies reveal that VH families arose prior to the mammalian radiation and have since been conserved, that this conservation appears to reflect selection at the level of protein sequence, and that the conserved regions are discretely localized on a solvent-exposed face of the heavy chain, at some distance from the antibody combining site. A family-specific region was also identified within the recombinase recognition sequences. Our results provide a context for theories that address the physiological significance of variations in VH family utilization during the development of the immune repertoire.

Early restriction of the human antibody repertoire

Diversification of the antibody repertoire in mammals results from a series of apparently random somatically propagated gene rearrangement and mutational events. Nevertheless, it is well known that the adult repertoire of antibody specificities is acquired in a developmentally programmed fashion. As previously shown, rearrangement of the gene segments encoding the heavy-chain variable regions (VH) of mouse antibodies is also developmentally ordered: the number of VH gene segments rearranged in B lymphocytes of fetal mice is small but increased progressively after birth. In this report, human fetal B-lineage cells were also shown to rearrange a highly restricted set of VH gene segments. In a sample of heavy-chain transcripts from a 130-day human fetus the most frequently expressed human VH element proved to be closely related to the VH element most frequently expressed in murine fetal B-lineage cells. These observations are important in understanding the development of immunocompetence.