PolySialic Acid Nanoparticles Actuate Complement-Factor-H-Mediated Inhibition of the Alternative Complement Pathway: A Safer Potential Therapy for Age-Related Macular Degeneration

The alternative pathway of the complement system is implicated in the etiology of age-related macular degeneration (AMD). Complement depletion with pegcetacoplan and avacincaptad pegol are FDA-approved treatments for geographic atrophy in AMD that, while effective, have clinically observed risks of choroidal neovascular (CNV) conversion, optic neuritis, and retinal vasculitis, leaving room for other equally efficacious but safer therapeutics, including Poly Sialic acid (PSA) nanoparticle (PolySia-NP)-actuated complement factor H (CFH) alternative pathway inhibition. Our previous paper demonstrated that PolySia-NP inhibits pro-inflammatory polarization and cytokine release. Here, we extend these findings by investigating the therapeutic potential of PolySia-NP to attenuate the alternative complement pathway. First, we show that PolySia-NP binds CFH and enhances affinity to C3b. Next, we demonstrate that PolySia-NP treatment of human serum suppresses alternative pathway hemolytic activity and C3b deposition. Further, we show that treating human macrophages with PolySia-NP is non-toxic and reduces markers of complement activity. Finally, we describe PolySia-NP-treatment-induced decreases in neovascularization and inflammatory response in a laser-induced CNV mouse model of neovascular AMD. In conclusion, PolySia-NP suppresses alternative pathway complement activity in human serum, human macrophage, and mouse CNV without increasing neovascularization.

Human IgG Fc-engineering for enhanced plasma half-life, mucosal distribution and killing of cancer cells and bacteria

Monoclonal IgG antibodies constitute the fastest growing class of therapeutics. Thus, there is an intense interest to design more potent antibody formats, where long plasma half-life is a commercially competitive differentiator affecting dosing, frequency of administration and thereby potentially patient compliance. Here, we report on an Fc-engineered variant with three amino acid substitutions Q311R/M428E/N434W (REW), that enhances plasma half-life and mucosal distribution, as well as allows for needle-free delivery across respiratory epithelial barriers in human FcRn transgenic mice. In addition, the Fc-engineered variant improves on-target complement-mediated killing of cancer cells as well as both gram-positive and gram-negative bacteria. Hence, this versatile Fc technology should be broadly applicable in antibody design aiming for long-acting prophylactic or therapeutic interventions.

Mechanisms by which Factor H protects Trypanosoma cruzi from the alternative pathway of complement

Chagas disease, a chronic disabling disease caused by the protozoan Trypanosoma cruzi, has no standardized treatment or preventative vaccine. The infective trypomastigote form of T. cruzi is highly resistant to killing by the complement immune system. Factor H (FH), a negative regulator of the alternative pathway (AP) of complement on cell surfaces and in blood, contains 20 short consensus repeat domains. The four N-terminal domains of FH inactivate the AP, while the other domains interact with C3b/d and glycan markers on cell surfaces. Various pathogens bind FH to inactivate the AP. T. cruzi uses its trans-sialidase enzyme to transfer host sialic acids to its own surface, which could be one of the approaches it uses to bind FH. Previous studies have shown that FH binds to complement-opsonized T. cruzi and parasite desialylation increases complement-mediated lysis of trypomastigotes. However, the molecular basis of FH binding to T. cruzi remain unknown. Only trypomastigotes, but not epimastigotes (non-infective, complement susceptible) bound FH directly, independent of C3 deposition, in a dose-dependent manner. Domain mapping experiments using 3-5 FH domain fragments showed that domains 5-8 competitively inhibited FH binding to the trypomastigotes by ~35% but did not decrease survival in complement. FH-Fc or mutant FH-Fc fusion proteins (3-11 contiguous FH domains fused to the IgG Fc) also did not kill trypomastigotes. FH-related protein-5, whose domains bear significant sequence identity to all known polyanion-binding FH domains (6-7, 10-14, 19-20), fully inhibited FH binding to trypomastigotes and reduced trypomastigote survival to < 24% in the presence of serum. In conclusion, we have elucidated the role of FH in complement resistance of trypomastigotes.

Preclinical efficacy of a cell division protein candidate gonococcal vaccine identified by artificial intelligence

A safe and effective vaccine is urgently needed to combat the global threat of multidrug-resistant (MDR) Neisseria gonorrhoeae. We screened 26 gonococcal proteins discovered by an artificial intelligence-driven platform called Efficacy Discriminative Educated Network (EDEN) trained to identify novel, protective vaccine antigens against pathogenic bacteria for efficacy in the mouse vaginal colonization model of gonorrhea. Combinations of two to three antigens adjuvanted with GLA-SE (induces TH1 responses) yielded 11 groups that were used to vaccinate mice. An inverse correlation was noted between the complement-dependent bactericidal activity of antisera from each of the 11 groups and the burden of gonococcal colonization. The combination of NGO1549 (FtsN; cell divisome protein) and NGO0265 (predicted cell division protein) most substantially reduced the burden of colonization by MDR strain WHO X. The EDEN prediction score for each group of antigens correlated positively with reductions in overall bacterial burden, providing evidence for its predictive potential. FtsN and NGO0265 administered either individually, in combination, or as a chimeric protein significantly attenuated gonococcal vaginal colonization by all three test strains. IgG in antisera from mice immunized with the chimeric NGO0265-FtsN protein supported the complement-dependent killing of all 50 (100%) gonococcal isolates tested. The efficacy of the chimeric NGO0265-FtsN vaccine required the membrane attack complex (C5b-9) of complement, evidenced by loss of efficacy in complement C9-/- mice. In conclusion, a chimeric molecule comprising NGO0265 and FtsN adjuvanted with GLA-SE elicits IgG with broad anti-gonococcal bactericidal activity, attenuates gonococcal colonization in a complement-dependent manner, and represents a promising gonococcal vaccine candidate.IMPORTANCEVaccines to curb the global spread of multidrug-resistant gonorrhea are urgently needed. Here, 26 vaccine candidates identified by an artificial intelligence-driven platform (Efficacy Discriminative Educated Network[EDEN]) were screened for efficacy in the mouse vaginal colonization model. Complement-dependent bactericidal activity of antisera and the EDEN protective scores both correlated positively with the reduction in overall bacterial colonization burden. NGO1549 (FtsN) and NGO0265, both involved in cell division, displayed the best activity and were selected for further development. Both antigens, when fused to create a chimeric protein, elicited bactericidal antibodies against a wide array of gonococcal isolates and significantly attenuated the duration and burden of gonococcal colonization of mouse vaginas. Protection was abrogated in mice that lacked complement C9, the last step in the formation of the membrane attack complex pore, suggesting complement-dependent bactericidal activity as a mechanistic correlate of protection of the vaccine. FtsN and NGO0265 represent promising vaccine candidates against gonorrhea.

Alternative pathway amplification and infections

The alternative pathway (AP) is the phylogenetically oldest arm of the complement system and may have evolved to mark pathogens for elimination by phagocytes. Studies using purified AP proteins or AP-specific serum showed that C3b amplification on bacteria commenced following a lag phase of about 5 min and was highly dependent on the concentration of complement. Most pathogens have evolved several elegant mechanisms to evade complement, including expressing proteases that degrade AP proteins and secreting proteins that block function of C3 convertases. In an example of convergent evolution, many microbes recruit the AP inhibitor factor H (FH) using molecular mechanisms that mimic FH interactions with host cells. In most instances, the AP serves to amplify C3b deposited on microbes by the classical pathway (CP). The role of properdin on microbes appears to be restricted to stabilization of C3 convertases; scant evidence exists for its role as an initiator of the AP on pathogens in the context of serum. Therapeutic complement inhibition carries with it an increased risk of infection. Antibody (Ab)-dependent AP activation may be critical for complement activation by vaccine-elicited Ab when the CP is blocked, and its molecular mechanism is discussed.

An optimized Factor H-Fc fusion protein against multidrug-resistant Neisseria gonorrhoeae

Novel therapeutics against the global threat of multidrug-resistant Neisseria gonorrhoeae are urgently needed. Gonococci evade killing by complement by binding factor H (FH), a key inhibitor of the alternative pathway. FH comprises 20 short consensus repeat (SCR) domains organized as a single chain. Gonococci bind FH through domains 6 and 7, and C-terminal domains 18 through 20. Previously, we showed that a chimeric protein comprising (from the N- to C-terminus) FH domains 18-20 (containing a point mutation in domain 19 to prevent lysis of host cells) fused to human IgG1 Fc (called FH*/Fc1) killed gonococci in a complement-dependent manner and reduced the duration and bacterial burden in the mouse vaginal colonization model of gonorrhea. Considering the N. gonorrhoeae-binding FH domains 18-20 are C-terminal in native FH, we reasoned that positioning Fc N-terminal to FH* (Fc1/FH*) would improve binding and bactericidal activity. Although both molecules bound gonococci similarly, Fc1/FH* displayed a 5-fold lower IC50 (the concentration required for 50% killing in complement-dependent bactericidal assays) than FH*/Fc1. To further increase complement activation, we replaced human IgG1 Fc in Fc1/FH* with Fc from human IgG3, the most potent complement-activating IgG subclass, to obtain Fc3/FH*. Bactericidal activity was further increased ~2.3-fold in Fc3/FH* compared to Fc1/FH*. Fc3/FH* killed (defined by <50% survival) 45/45 (100%) diverse PorB1B-expessing gonococci, but only 2/15 PorB1A-expressing isolates, in a complement-dependent manner. Decreased Fc3/FH* binding accounted for the limited activity against PorB1A strains. Fc3/FH* was efficacious against all four tested PorB1B gonococcal strains in the mouse vaginal colonization model when administered at a dose of 5 µg intravaginally, daily. Furthermore, Fc3/FH* retained bactericidal activity when reconstituted following lyophilization or spray-drying, suggesting feasibility for formulation into intravaginal rings. In conclusion, Fc3/FH* represents a promising prophylactic immunotherapeutic against multidrug-resistant gonococci.

Mechanisms by which Factor H protects Trypanosoma cruzi from the alternative pathway of complement

Chagas disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi (T. cruzi). Complement (C) is a critical arm of the immune system. Various pathogens, including T. cruzi, hijack host regulators such as Factor H (FH) to inactivate C. FH regulates the alternative pathway (AP) of C in blood and on cell surfaces. FH contains 20 short consensus repeat (SCR) domains and binds to C activation products (i.e., C3b/C3d) or polyanionic host cell markers (e.g., sialic acid, glycosaminoglycans) on cell surfaces, and uses its 4 N-terminal SCRs to inactivate the AP. T. cruzi potentially binds FH by transferring host sialic acids onto its surface using its trans-sialidase enzyme. This study asked whether FH binds directly to T. cruzi in the absence of C3b and defines the FH domains involved. Only C-resistant infective trypomastigotes, but not C-sensitive noninfective epimastigotes, bound FH directly in a dose-dependent manner. Although SCR 19–20 was hypothesized as important for this interaction given it is the only known sialic acid-binding region, domain mapping indicated SCR 5–8 competitively inhibited FH binding by &gt;35% with lower contributions of other regions. FH related protein-5 (FHR-5), whose SCRs bear sequence homology to all known polyanion-binding regions (6–7, 10–14, 19–20), fully competitively inhibited FH binding to trypomastigotes. In addition, competitive survival experiments with serum and FHR-5 led to &gt;80% killing when the AP or all C pathways were active. This is the first study to show consequences of completely inhibiting FH protection on T. cruzi and to suggest multiple FH domains are involved in the interaction. These data may be harnessed for developing therapeutics and vaccine candidates against T. cruzi.

This work was supported by The University of Toledo Biomedical Research Innovation Program (VF), and The American Association of Immunologists Careers in Immunology Fellowship Program (VF and SSM). 

Development of Complement Factor H-Based Immunotherapeutic Molecules in Tobacco Plants Against Multidrug-Resistant Neisseria gonorrhoeae

Novel therapeutics against the global threat of multidrug-resistant Neisseria gonorrhoeae are urgently needed. Gonococci possess several mechanisms to evade killing by human complement, including binding of factor H (FH), a key inhibitor of the alternative pathway. FH comprises 20 short consensus repeat (SCR) domains organized in a head-to-tail manner as a single chain. N. gonorrhoeae binds two regions in FH; domains 6 and 7 and domains 18 through 20. We designed a novel anti-infective immunotherapeutic molecule that fuses domains 18-20 of FH containing a D-to-G mutation in domain 19 at position 1119 (called FH*) with human IgG1 Fc. FH*/Fc retained binding to gonococci but did not lyse human erythrocytes. Expression of FH*/Fc in tobacco plants was undertaken as an alternative, economical production platform. FH*/Fc was expressed in high yields in tobacco plants (300-600 mg/kg biomass). The activities of plant- and CHO-cell produced FH*/Fc against gonococci were similar in vitro and in the mouse vaginal colonization model of gonorrhea. The addition of flexible linkers [e.g., (GGGGS)2 or (GGGGS)3] between FH* and Fc improved the bactericidal efficacy of FH*/Fc 2.7-fold. The linkers also improved PMN-mediated opsonophagocytosis about 11-fold. FH*/Fc with linker also effectively reduced the duration and burden of colonization of two gonococcal strains tested in mice. FH*/Fc lost efficacy: i) in C6-/- mice (no terminal complement) and ii) when Fc was mutated to abrogate complement activation, suggesting that an intact complement was necessary for FH*/Fc function in vivo. In summary, plant-produced FH*/Fc represent promising prophylactic or adjunctive immunotherapeutics against multidrug-resistant gonococci.

C4BP-IgM protein as a therapeutic approach to treat Neisseria gonorrhoeae infections

Gonorrhea is a sexually transmitted infection with 87 million new cases per year globally. Increasing antibiotic resistance has severely limited treatment options. A mechanism that Neisseria gonorrhoeae uses to evade complement attack is binding of the complement inhibitor C4b-binding protein (C4BP). We screened 107 porin B1a (PorB1a) and 83 PorB1b clinical isolates randomly selected from a Swedish strain collection over the last 10 years and noted that 96/107 (89.7%) PorB1a and 16/83 (19.3%) PorB1b bound C4BP; C4BP binding substantially correlated with the ability to evade complement-dependent killing (r = 0.78). We designed 2 chimeric proteins that fused C4BP domains to the backbone of IgG or IgM (C4BP-IgG; C4BP-IgM) with the aim of enhancing complement activation and killing of gonococci. Both proteins bound gonococci (KD C4BP-IgM = 2.4 nM; KD C4BP-IgG 980.7 nM), but only hexameric C4BP-IgM efficiently outcompeted heptameric C4BP from the bacterial surface, resulting in enhanced complement deposition and bacterial killing. Furthermore, C4BP-IgM substantially attenuated the duration and burden of colonization of 2 C4BP-binding gonococcal isolates but not a non-C4BP-binding strain in a mouse vaginal colonization model using human factor H/C4BP-transgenic mice. Our preclinical data present C4BP-IgM as an adjunct to conventional antimicrobials for the treatment of gonorrhea.

Complement alone drives efficacy of a chimeric antigonococcal monoclonal antibody

Multidrug-resistant Neisseria gonorrhoeae is a global health problem. Monoclonal antibody (mAb) 2C7 recognizes a gonococcal lipooligosaccharide epitope that is expressed by >95% of clinical isolates and hastens gonococcal vaginal clearance in mice. Chimeric mAb 2C7 (human immunoglobulin G1 [IgG1]) with an E430G Fc modification that enhances Fc:Fc interactions and hexamerization following surface-target binding and increases complement activation (HexaBody technology) showed significantly greater C1q engagement and C4 and C3 deposition compared to mAb 2C7 with wild-type Fc. Greater complement activation by 2C7-E430G Fc translated to increased bactericidal activity in vitro and, consequently, enhanced efficacy in mice, compared with “Fc-unmodified” chimeric 2C7. Gonococci bind the complement inhibitors factor H (FH) and C4b-binding protein (C4BP) in a human-specific manner, which dampens antibody (Ab)-mediated complement-dependent killing. The variant 2C7-E430G Fc overcame the barrier posed by these inhibitors in human FH/C4BP transgenic mice, for which a single 1 μg intravenous dose cleared established infection. Chlamydia frequently coexists with and exacerbates gonorrhea; 2C7-E430G Fc also proved effective against gonorrhea in gonorrhea/chlamydia-coinfected mice. Complement activation alone was necessary and sufficient for 2C7 function, evidenced by the fact that (1) “complement-inactive” Fc modifications that engaged Fc gamma receptor (FcγR) rendered 2C7 ineffective, nonetheless; (2) 2C7 was nonfunctional in C1q^−/− mice, when C5 function was blocked, or in C9^−/− mice; and (3) 2C7 remained effective in neutrophil-depleted mice and in mice treated with PMX205, a C5a receptor (C5aR1) inhibitor. We highlight the importance of complement activation for antigonococcal Ab function in the genital tract. Elucidating the correlates of protection against gonorrhea will inform the development of Ab-based gonococcal vaccines and immunotherapeutics.

A chimeric antibody that contains a "complement-enhancing" mutation in Fc (so-called HexaBody technology) shows increased bactericidal activity compared to antibody bearing wild-type Fc and may represent a promising immunotherapeutic approach against multidrug-resistant gonorrhea.

Targeting Lipooligosaccharide (LOS) for a Gonococcal Vaccine

The increasing incidence of gonorrhea worldwide and the global spread of multidrug-resistant strains of Neisseria gonorrhoeae, constitute a public health emergency. With dwindling antibiotic treatment options, there is an urgent need to develop safe and effective vaccines. Gonococcal lipooligosaccharides (LOSs) are potential vaccine candidates because they are densely represented on the bacterial surface and are readily accessible as targets of adaptive immunity. Less well-understood is whether LOSs evoke protective immune responses. Although gonococcal LOS-derived oligosaccharides (OSs) are major immune targets, often they undergo phase variation, a feature that seemingly makes LOS less desirable as a vaccine candidate. However, the identification of a gonococcal LOS-derived OS epitope, called 2C7, that is: (i) a broadly expressed gonococcal antigenic target in human infection; (ii) a virulence determinant, that is maintained by the gonococcus and (iii) a critical requirement for gonococcal colonization in the experimental setting, circumvents its limitation as a potential vaccine candidate imposed by phase variation. Difficulties in purifying structurally intact OSs from LOSs led to "conversion" of the 2C7 epitope into a peptide mimic that elicited cross-reactive IgG anti-OS antibodies that also possess complement-dependent bactericidal activity against gonococci. Mice immunized with the 2C7 peptide mimic clear vaginal colonization more rapidly and reduce gonococcal burdens. 2C7 vaccine satisfies criteria that are desirable in a gonococcal vaccine candidate: broad representation of the antigenic target, service as a virulence determinant that is also critical for organism survival in vivo and elicitation of broadly cross-reactive IgG bactericidal antibodies when used as an immunogen.

Candida albicans Factor H Binding Molecule Hgt1p - A Low Glucose-Induced Transmembrane Protein Is Trafficked to the Cell Wall and Impairs Phagocytosis and Killing by Human Neutrophils

Complement is a tightly controlled arm of the innate immune system, facilitating phagocytosis and killing of invading pathogens. Factor H (FH) is the main fluid-phase inhibitor of the alternative pathway. Many pathogens can hijack FH from the host and protect themselves from complement-dependent killing. Candida albicans is a clinically important opportunistic yeast, expressing different FH binding molecules on its cell surface, which allow complement evasion. One such FH binding molecule is the transmembrane protein "High affinity glucose transporter 1" (Hgt1p), involved in glucose metabolism. This study demonstrated that Hgt1p transcription and expression is induced and highest at the low, but physiological glucose concentration of 0.1%. Thus, this concentration was used throughout the study. We also demonstrated the transport of Hgt1p to the fungal cell wall surface by vesicle trafficking and its release by exosomes containing Hgt1p integrated in the vesicular membrane. We corroborated Hgt1p as FH binding molecule. A polyclonal anti-Hgt1p antibody was created which interfered with the binding of FH, present in normal human serum to the fungal cell wall. A chimeric molecule consisting of FH domains 6 and 7 fused to human IgG1 Fc (FH6.7/Fc) even more comprehensively blocked FH binding, likely because FH6.7/Fc diverted FH away from fungal FH ligands other than Hgt1p. Reduced FH binding to the yeast was associated with a concomitant increase in C3b/iC3b deposition and resulted in significantly increased in vitro phagocytosis and killing by human neutrophils. In conclusion, Hgt1p also exhibits non-canonical functions such as binding FH after its export to the cell wall. Blocking Hgt1p-FH interactions may represent a tool to enhance complement activation on the fungal surface to promote phagocytosis and killing of C. albicans.

Biology of the Gonococcus: Disease and Pathogenesis

Neisseria gonorrhoeae infection is a major public health problem worldwide. The increasing incidence of gonorrhea coupled with global spread of multidrug-resistant isolates of gonococci has ushered in an era of potentially untreatable infection. Gonococcal disease elicits limited immunity, and individuals are susceptible to repeated infections. In this chapter, we describe gonococcal disease and epidemiology and the structure and function of major surface components involved in pathogenesis. We also discuss the mechanisms that gonococci use to evade host immune responses and the immune responses following immunization with selected bacterial components that may overcome evasion. Understanding the biology of the gonococcus may aid in preventing the spread of gonorrhea and also facilitate the development of gonococcal vaccines and treatments.

Human Factor H Domains 6 and 7 Fused to IgG1 Fc Are Immunotherapeutic against Neisseria gonorrhoeae

Novel therapeutics against multidrug-resistant Neisseria gonorrhoeae are urgently needed. Gonococcal lipooligosaccharide often expresses lacto-N-neotetraose (LNnT), which becomes sialylated in vivo, enhancing factor H (FH) binding and contributing to the organism's ability to resist killing by complement. We previously showed that FH domains 18-20 (with a D-to-G mutation at position 1119 in domain 19) fused to Fc (FHD1119G/Fc) displayed complement-dependent bactericidal activity in vitro and attenuated gonococcal vaginal colonization of mice. Gonococcal lipooligosaccharide phase variation can result in loss of LNnT expression. Loss of sialylated LNnT, although associated with a considerable fitness cost, could decrease efficacy of FHD1119G/Fc. Similar to N. meningitidis, gonococci also bind FH domains 6 and 7 through Neisserial surface protein A (NspA). In this study, we show that a fusion protein comprising FH domains 6 and 7 fused to human IgG1 Fc (FH6,7/Fc) bound to 15 wild-type antimicrobial resistant isolates of N. gonorrhoeae and to each of six lgtA gonococcal deletion mutants. FH6,7/Fc mediated complement-dependent killing of 8 of the 15 wild-type gonococcal isolates and effectively reduced the duration and burden of vaginal colonization of three gonococcal strains tested in wild-type mice, including two strains that resisted complement-dependent killing but on which FH6,7/Fc enhanced C3 deposition. FH/Fc lost efficacy when Fc was mutated to abrogate C1q binding and in C1q-/- mice, highlighting the requirement of the classical pathway for its activity. Targeting gonococci with FH6,7/Fc provides an additional immunotherapeutic approach against multidrug-resistant gonorrhea.

Human IgG Increases Virulence of Streptococcus pyogenes through Complement Evasion

Streptococcus pyogenes is an exclusively human pathogen that can provoke mild skin and throat infections but can also cause fatal septicemia. This gram-positive bacterium has developed several strategies to evade the human immune system, enabling S. pyogenes to survive in the host. These strategies include recruiting several human plasma proteins, such as the complement inhibitor, C4b-binding protein (C4BP), and human (hu)-IgG through its Fc region to the bacterial surface to evade immune recognition. We identified a novel virulence mechanism whereby IgG-enhanced binding of C4BP to five of 12 tested S. pyogenes strains expressed diverse M proteins that are important surface-expressed virulence factors. Importantly, all strains that bound C4BP in the absence of IgG bound more C4BP when IgG was present. Further studies with an M1 strain that additionally expressed protein H, also a member of the M protein family, revealed that binding of hu-IgG Fc to protein H increased the affinity of protein H for C4BP. Increased C4BP binding accentuated complement downregulation, resulting in diminished bacterial killing. Accordingly, mortality from S. pyogenes infection in hu-C4BP transgenic mice was increased when hu-IgG or its Fc portion alone was administered concomitantly. Electron microscopy analysis of human tissue samples with necrotizing fasciitis confirmed increased C4BP binding to S. pyogenes when IgG was present. Our findings provide evidence of a paradoxical function of hu-IgG bound through Fc to diverse S. pyogenes isolates that increases their virulence and may counteract the beneficial effects of IgG opsonization.

Factor H-IgG Chimeric Proteins as a Therapeutic Approach against the Gram-Positive Bacterial Pathogen Streptococcus pyogenes

Bacteria can cause life-threatening infections, such as pneumonia, meningitis, or sepsis. Antibiotic therapy is a mainstay of treatment, although antimicrobial resistance has drastically increased over the years. Unfortunately, safe and effective vaccines against most pathogens have not yet been approved, and thus developing alternative treatments is important. We analyzed the efficiency of factor H (FH)6-7/Fc, a novel antibacterial immunotherapeutic protein against the Gram-positive bacterium Streptococcus pyogenes This protein is composed of two domains of complement inhibitor human FH (FH complement control protein modules 6 and 7) that bind to S. pyogenes, linked to the Fc region of IgG (FH6-7/Fc). FH6-7/Fc has previously been shown to enhance complement-dependent killing of, and facilitate bacterial clearance in, animal models of the Gram-negative pathogens Haemophilus influenzae and Neisseria meningitidis We hypothesized that activation of complement by FH6-7/Fc on the surface of Gram-positive bacteria such as S. pyogenes will enable professional phagocytes to eliminate the pathogen. We found that FH6-7/Fc alleviated S. pyogenes-induced sepsis in a transgenic mouse model expressing human FH (S. pyogenes binds FH in a human-specific manner). Furthermore, FH6-7/Fc, which binds to protein H and selected M proteins, displaced FH from the bacterial surface, enhanced alternative pathway activation, and reduced bacterial blood burden by opsonophagocytosis in a C3-dependent manner in an ex vivo human whole-blood model. In conclusion, FH-Fc chimeric proteins could serve as adjunctive treatments against multidrug-resistant bacterial infections.

Gonococcal lipooligosaccharide sialylation: virulence factor and target for novel immunotherapeutics

Gonorrhea has become resistant to most conventional antimicrobials used in clinical practice. The global spread of multidrug-resistant isolates of Neisseria gonorrhoeae could lead to an era of untreatable gonorrhea. New therapeutic modalities with novel mechanisms of action that do not lend themselves to the development of resistance are urgently needed. Gonococcal lipooligosaccharide (LOS) sialylation is critical for complement resistance and for establishing infection in humans and experimental mouse models. Here we describe two immunotherapeutic approaches that target LOS sialic acid: (i) a fusion protein that comprises the region in the complement inhibitor factor H (FH) that binds to sialylated gonococci and IgG Fc (FH/Fc fusion protein) and (ii) analogs of sialic acid that are incorporated into LOS but fail to protect the bacterium against killing. Both molecules showed efficacy in the mouse vaginal colonization model of gonorrhea and may represent promising immunotherapeutic approaches to target multidrug-resistant isolates. Disabling key gonococcal virulence mechanisms is an effective therapeutic strategy because the reduction of virulence is likely to be accompanied by a loss of fitness, rapid elimination by host immunity and consequently, decreased transmission.

Utilizing complement evasion strategies to design complement-based antibacterial immunotherapeutics: Lessons from the pathogenic Neisseriae

Novel therapies are urgently needed to combat the global threat of multidrug-resistant pathogens. Complement forms an important arm of innate defenses against infections. In physiological conditions, complement activation is tightly controlled by soluble and membrane-associated complement inhibitors, but must be selectively activated on invading pathogens to facilitate microbial clearance. Many pathogens, including Neisseria gonorrhoeae and N. meningitidis, express glycans, including N-acetylneuraminic acid (Neu5Ac), that mimic host structures to evade host immunity. Neu5Ac is a negatively charged 9-cabon sugar that inhibits complement, in part by enhancing binding of the complement inhibitor factor H (FH) through C-terminal domains (19 and 20) on FH. Other microbes also bind FH, in most instances through FH domains 6 and 7 or 18-20. Here we describe two strategies to target complement activation on Neisseriae. First, microbial binding domains of FH were fused to IgG Fc to create FH18-20/Fc (binds gonococci) and FH6,7/Fc (binds meningococci). A point mutation in FH domain 19 eliminated hemolysis caused by unmodified FH18-20, but retained binding to gonococci. FH18-20/Fc and FH6,7/Fc mediated complement-dependent killing in vitro and showed efficacy in animal models of gonorrhea and meningococcal bacteremia, respectively. The second strategy utilized CMP-nonulosonate (CMP-NulO) analogs of sialic acid that were incorporated into LOS and prevented complement inhibition by physiologic CMP-Neu5Ac and resulted in attenuated gonococcal infection in mice. While studies to establish the safety of these agents are needed, enhancing complement activation on microbes may represent a promising strategy to treat antimicrobial resistant organisms.

Defining the Binding Region in Factor H to Develop a Therapeutic Factor H-Fc Fusion Protein against Non-Typeable Haemophilus influenzae

Non-typeable Haemophilus influenzae (NTHi) cause a range of illnesses including otitis media, sinusitis, and exacerbation of chronic obstructive pulmonary disease, infections that contribute to the problem of antibiotic resistance and are themselves often intractable to standard antibiotic treatment regimens. We investigated a strategy to exploit binding of the complement inhibitor Factor H (FH) to NTHi as a functional target for an immunotherapeutic containing the NTHi binding domain of FH fused to the Fc domain of IgG1. Chimeric proteins containing the regions that most FH-binding bacteria use to engage human FH, domains 6 and 7 (FH6,7/Fc) and/or 18 through 20 (FH18-20/Fc), were evaluated for binding to NTHi. FH6,7/Fc bound strongly to each of seven NTHi clinical isolates tested and efficiently promoted complement-mediated killing by normal human serum. FH18-20/Fc bound weakly to three of the strains but did not promote complement dependent killing. Outer-membrane protein P5 has been implicated in FH binding by NTHi, and FH6,7/Fc binding was greatly diminished in five of seven P5 deficient isogenic mutant strains tested, implicating an alternative FH binding protein in some strains. Binding of FH18-20/Fc was decreased in the P5 mutant of one strain. A murine model was used to evaluate potential therapeutic application of FH6,7/Fc. FH6,7/Fc efficiently promoted binding of C3 to NTHi exposed to mouse serum, and intranasal delivery of FH6,7/Fc resulted in significantly enhanced clearance of NTHi from the lung. Moreover, a P5 deficient mutant was attenuated for survival in the lung model, suggesting that escape mutants lacking P5 would be less likely to replace strains susceptible to FH6,7/Fc. These results provide evidence for the potential utility of FH6,7/Fc as a therapeutic against NTHi lung infection. FH binding is a common property of many respiratory tract pathogens and FH/Fc chimeras may represent promising alternative or adjunctive therapeutics against such infections, which are often polymicrobial.

A Novel Factor H-Fc Chimeric Immunotherapeutic Molecule against Neisseria gonorrhoeae

Neisseria gonorrhoeae, the causative agent of the sexually transmitted infection gonorrhea, has developed resistance to almost every conventional antibiotic. There is an urgent need to develop novel therapies against gonorrhea. Many pathogens, including N. gonorrhoeae, bind the complement inhibitor factor H (FH) to evade complement-dependent killing. Sialylation of gonococcal lipooligosaccharide, as occurs in vivo, augments binding of human FH through its domains 18-20 (FH18-20). We explored the use of fusing FH18-20 with IgG Fc (FH18-20/Fc) to create a novel anti-infective immunotherapeutic. FH18-20 also binds to select host glycosaminoglycans to limit unwanted complement activation on host cells. To identify mutation(s) in FH18-20 that eliminated complement activation on host cells, yet maintained binding to N. gonorrhoeae, we created four mutations in domains 19 or 20 described in atypical hemolytic uremic syndrome that prevented binding of mutated fH to human erythrocytes. One of the mutant proteins (D to G at position 1119 in domain 19; FHD1119G/Fc) facilitated complement-dependent killing of gonococci similar to unmodified FH18-20/Fc but, unlike FH18-20/Fc, did not lyse human erythrocytes. FHD1119G/Fc bound to all (100%) of 15 sialylated clinical N. gonorrhoeae isolates tested (including three contemporary ceftriaxone-resistant strains), mediated complement-dependent killing of 10 of 15 (67%) strains, and enhanced C3 deposition (≥10-fold above baseline levels) on each of the five isolates not directly killed by complement. FHD1119G/Fc facilitated opsonophagocytic killing of a serum-resistant strain by human polymorphonuclear neutrophils. FHD1119G/Fc administered intravaginally significantly reduced the duration and burden of gonococcal infection in the mouse vaginal colonization model. FHD1119G/Fc represents a novel immunotherapeutic against multidrug-resistant N. gonorrhoeae.

The effect of human factor H on immunogenicity of meningococcal native outer membrane vesicle vaccines with over-expressed factor H binding protein

The binding of human complement inhibitors to vaccine antigens in vivo could diminish their immunogenicity. A meningococcal ligand for the complement down-regulator, factor H (fH), is fH-binding protein (fHbp), which is specific for human fH. Vaccines containing recombinant fHbp or native outer membrane vesicles (NOMV) from mutant strains with over-expressed fHbp are in clinical development. In a previous study in transgenic mice, the presence of human fH impaired the immunogenicity of a recombinant fHbp vaccine. In the present study, we prepared two NOMV vaccines from mutant group B strains with over-expressed wild-type fHbp or an R41S mutant fHbp with no detectable fH binding. In wild-type mice in which mouse fH did not bind to fHbp in either vaccine, the NOMV vaccine with wild-type fHbp elicited 2-fold higher serum IgG anti-fHbp titers (P = 0.001) and 4-fold higher complement-mediated bactericidal titers against a PorA-heterologous strain than the NOMV with the mutant fHbp (P = 0.003). By adsorption, the bactericidal antibodies were shown to be directed at fHbp. In transgenic mice in which human fH bound to the wild-type fHbp but not to the R41S fHbp, the NOMV vaccine with the mutant fHbp elicited 5-fold higher serum IgG anti-fHbp titers (P = 0.002), and 19-fold higher bactericidal titers than the NOMV vaccine with wild-type fHbp (P = 0.001). Thus, in mice that differed only by the presence of human fH, the respective results with the two vaccines were opposite. The enhanced bactericidal activity elicited by the mutant fHbp vaccine in the presence of human fH far outweighed the loss of immunogenicity of the mutant protein in wild-type animals. Engineering fHbp not to bind to its cognate complement inhibitor, therefore, may increase vaccine immunogenicity in humans.

Vaccines containing factor H-binding protein (fHbp) are being developed for protection against bacterial meningitis and sepsis caused by meningococci. The antigen was identified from genomic sequences and only later found to bind a human complement protein, factor H (fH), but not fH from non-human species. In previous studies, native outer membrane vesicle (NOMV) vaccines from mutants with over-expressed fHbp elicited broadly protective serum antibodies in mice whose fH did not bind to fHbp in the vaccine. In this study, the authors immunized transgenic mice and showed that the presence of human fH decreased serum bactericidal antibody responses to a NOMV vaccine with fHbp that bound human fH. In contrast, a NOMV vaccine containing fHbp with a single amino acid substitution that eliminated fH binding elicited nearly twenty-fold higher protective antibody responses. Thus, a simple change in a vaccine antigen to eliminate binding to a host protein can increase immunogenicity.

Molecular characterization of the interaction between sialylated Neisseria gonorrhoeae and factor H

Human factor H (HufH), a key inhibitor of the alternative pathway of complement, binds to Neisseria gonorrhoeae and constitutes an important mechanism of human-specific complement evasion. The C-terminal domain 20 of HufH contains the binding site for sialylated gonococci. We exploited differences in amino acid sequences between human and non-binding chimpanzee fH domain 20 to create cross-species mutations to define amino acids important for binding to sialylated gonococci. We used fH/Fc fusion constructs that contained contiguous fH domains 18-20 fused to Fc fragments of murine IgG2a. The Fc region was used both as a tag for detection of each fusion molecule on the bacterial surface and as an indicator for complement-dependent killing. Arg-1203 was critical for binding to both porin (Por) B.1A and PorB.1B strains. Modeling of the R1203N human-to-chimpanzee mutation using the crystal structure of HufH19-20 as a template showed a loss of positive charge that protrudes at the C terminus of domain 20. We tested the functional importance of Arg-1203 by incubating sialylated gonococci with normal human serum, in the presence of wild-type HufH18-20/Fc or its R1203A mutant. Gonococci bound and were killed by wild-type HufH18-20/Fc but not by the R1203A mutant. A recombinant fH/Fc molecule that contained chimpanzee domain 20, humanized only at amino acid 1203 (N1203R) also bound to sialylated gonococci and restored killing. These findings provide further insights into the species specificity of gonococcal infections and proof-of-concept of a novel therapeutic approach against gonorrhea, a disease rapidly becoming resistant to conventional antibiotics.

A meningococcal factor H binding protein mutant that eliminates factor H binding enhances protective antibody responses to vaccination

Certain pathogens recruit host complement inhibitors such as factor H (fH) to evade the immune system. Microbial complement inhibitor-binding molecules can be promising vaccine targets by eliciting Abs that neutralize this microbial defense mechanism. One such Ag, meningococcal factor H-binding protein (fHbp), was used in clinical trials before the protein was discovered to bind fH. The potential effect of fH binding on vaccine immunogenicity had not been assessed in experimental animals because fHbp binds human fH specifically. In this study, we developed a human fH transgenic mouse model. Transgenic mice immunized with fHbp vaccine had 4- to 8-fold lower serum bactericidal Ab responses than those of control mice whose native fH did not bind the vaccine. In contrast, Ab responses were unimpaired in transgenic mice immunized with a control meningococcal group C polysaccharide-protein conjugate vaccine. In transgenic mice, immunization with an fH nonbinding mutant of fHbp elicited Abs with higher bactericidal activity than that of fHbp vaccination itself. Abs elicited by the mutant fHbp more effectively blocked fH binding to wild-type fHbp than Abs elicited by fHbp that bound fH. Thus, a mutant fHbp vaccine that does not bind fH but that retains immunogenicity is predicted to be superior in humans to an fHbp vaccine that binds human fH. In the case of mutant fHbp vaccination, the resultant Ab responses may be directed more at epitopes in or near the fH binding site, which result in greater complement-mediated serum bactericidal activity; these epitopes may be obscured when human fH is bound to the wild-type fHbp vaccine.

International Myeloma Working Group molecular classification of multiple myeloma: spotlight review

Myeloma is a malignant proliferation of monoclonal plasma cells. Although morphologically similar, several subtypes of the disease have been identified at the genetic and molecular level. These genetic subtypes are associated with unique clinicopathological features and dissimilar outcome. At the top hierarchical level, myeloma can be divided into hyperdiploid and non-hyperdiploid subtypes. The latter is mainly composed of cases harboring IgH translocations, generally associated with more aggressive clinical features and shorter survival. The three main IgH translocations in myeloma are the t(11;14)(q13;q32), t(4;14)(p16;q32) and t(14;16)(q32;q23). Trisomies and a more indolent form of the disease characterize hyperdiploid myeloma. A number of genetic progression factors have been identified including deletions of chromosomes 13 and 17 and abnormalities of chromosome 1 (1p deletion and 1q amplification). Other key drivers of cell survival and proliferation have also been identified such as nuclear factor- B-activating mutations and other deregulation factors for the cyclin-dependent pathways regulators. Further understanding of the biological subtypes of the disease has come from the application of novel techniques such as gene expression profiling and array-based comparative genomic hybridization. The combination of data arising from these studies and that previously elucidated through other mechanisms allows for most myeloma cases to be classified under one of several genetic subtypes. This paper proposes a framework for the classification of myeloma subtypes and provides recommendations for genetic testing. This group proposes that genetic testing needs to be incorporated into daily clinical practice and also as an essential component of all ongoing and future clinical trials.

Genetic polymorphisms of EPHX1, Gsk3beta, TNFSF8 and myeloma cell DKK-1 expression linked to bone disease in myeloma

Bone disease in myeloma occurs as a result of complex interactions between myeloma cells and the bone marrow microenvironment. A custom-built DNA single nucleotide polymorphism (SNP) chip containing 3404 SNPs was used to test genomic DNA from myeloma patients classified by the extent of bone disease. Correlations identified with a Total Therapy 2 (TT2) (Arkansas) data set were validated with Eastern Cooperative Oncology Group (ECOG) and Southwest Oncology Group (SWOG) data sets. Univariate correlates with bone disease included: EPHX1, IGF1R, IL-4 and Gsk3beta. SNP signatures were linked to the number of bone lesions, log(2) DKK-1 myeloma cell expression levels and patient survival. Using stepwise multivariate regression analysis, the following SNPs: EPHX1 (P=0.0026); log(2) DKK-1 expression (P=0.0046); serum lactic dehydrogenase (LDH) (P=0.0074); Gsk3beta (P=0.02) and TNFSF8 (P=0.04) were linked to bone disease. This assessment of genetic polymorphisms identifies SNPs with both potential biological relevance and utility in prognostic models of myeloma bone disease.

Role of T-cell immunity to embryonal stem (ES) cell antigen SOX2 in the progression of myeloma

8522

Background: Clinical outcome in patients (pts) with asymptomatic plasma-proliferative disorders, monoclonal gammopathy of undetermined significance (MGUS) and asymptomatic myeloma (AMM), is highly variable. There is a need to identify specific tumor or host related features that predict the risk of disease progression. In prior studies, we have shown that patients with MGUS commonly mount a T cell immune response against SOX2, an antigen critical for pluripotency of ES cells. Methods: Patients with MGUS/AMM were enrolled in a prospective observational clinical protocol (SWOG S0120). All patients underwent detailed staging evaluation at registration and were observed without therapy. The presence of T cell immunity to SOX2 in freshly isolated blood / marrow mononuclear cells was analyzed using an overlapping peptide library at study entry. Results: Anti-SOX2 T cell responses were detected in 39/109 (36%) pts tested. Progression to symptomatic MM was observed in only 2 of 39 patients with anti-SOX2 immunity compared to 17 of 59 pts lacking these responses, resulting in 2-yr progression-free survival 96 v 63% (p=0.003). Responses to viral antigens and polyclonal mitogens as controls were preserved in patients lacking SOX2 immunity indicating that the absence of immunity to SOX2 was not due to global immune-suppression. Immunity to SOX2 correlated with features of lower risk including serum-M component < 1.5 g/dL (p=0.008), marrow plasmacytosis < 10% (p<0.001) and normal serum free light chain ratio (p=0.01). Conclusions: These data demonstrate in the context of a prospective trial that T cell immunity to stem cell genes strongly correlates with a reduced risk of progression to clinical myeloma. These data point to SOX2 as a potential target for the prevention of disease progression in MGUS/AMM.

No significant financial relationships to disclose.

Gene expression profiling (GEP)-defined risk and molecular subgroups assessed at baseline and at relapse: Collective impact on post-relapse survival of multiple myeloma (MM) treated with total therapies 2 and 3

8589

Background: GEP-defined risk has evolved as the most robust predictor of overall and event-free survival (OS, EFS) in MM with TT2 and TT3 protocols, distinguishing 85% with low-risk (LR) and 15% with high-risk (HR). Upon relapse, the original risk designation may change typically in the direction LR to HR. Here we examine, among patients with available GEP data at baseline (BL) and relapse (REL), the contributions of both observations on post-relapse survival (PRS). Methods: Paired REL-BL GEP data were available in 77 patients, while information on metaphase cytogenetic abnormalities (CA) was obtained in 76 patients at both time-points. Results: PRS was significantly affected by both BL and REL HR status so that, among the 52 patients with LR at BL, HR status at REL conferred significantly poorer outcome compared to those with LR at REL (p=0.0005) with 30-mo estimates of 71% v 13%; likewise, among the 25 patients with HR at baseline, HR present also at relapse further diminished PRS (p=0.09) with 30-mo estimates in both settings of less than 20%. Similar considerations for CA status revealed, among the 29 patients without CA at BL, marked attrition of PRS with CA v no CA at REL with 30-mo estimates of 29% v 81% (p=0.04); for the 47 patients with CA at BL, CA also at REL further diminished the poor PRS from 46% to 22% (p=0.06). When all standard BL and REL prognostic factors were examined in a multivariate model, GEP-derived HR contributed to poor PRS both when present at BL (HR=2.79, p=0.005) and at REL (HR=2.77, p=0.002), in addition to CA at BL (HR=2.44, p=0.018). Conclusions: In estimating PRS in TT protocols, genetic characteristics at BL (HR, CA) have enduring adverse consequences aggravated further by HR status at REL. Therefore, in HR/CA BL settings, aiming at REL prevention appears as the best overall treatment strategy.

[Table: see text]

Bone marrow microenvironment (ME) associated genes identified prior to all altered 48 hours after bortexomib test-dose application and prognosis of multiple myeloma (MM) treated with total therapy 3 (TT3)

8520

Background: Total Therapy 3 (TT3) incorporated bortezomib (BOR) to co-target ME that plays an important role in MM progression and drug resistance. Consenting patients received a BOR test dose of 1mg/m2 to determine whether ME alterations induced 48hr post-BOR could clarify the drug's in-vivo mechanism of action in the context of achieving MM control. Methods: Bone marrow biopsies were obtained at baseline (BL) prior to and 48hr after BOR (PB) in 70 of 303 patients receiving TT3a (training set) and in 45 of 177 patients enrolled in TT3b (test set). Among 608 ME genes distinguishing BL and PB training samples, 58 were identified as being significantly linked to short event-free survival (EFS). A summary score was computed based on the percent change of these 58 genes (PB-ME-S). Additionally, 20 ME genes were selected whose BL expression predicted OS, arriving at a BL score (BL-ME-S). Results: Applying the PB-ME-S score, 3-yr OS and EFS estimates were 96% and 96% among the 49 patients with low PB-ME-S and 50% and 38% in the 21 with high PB-ME-S (both p<0.0001). Follow-up is too short to validate the PB-ME-S model in the test set of 45 patients in TT3b. The BL-ME-S distinguished OS and EFS in the training set of 70 patients, with 3-yr OS and EFS estimates of 92% and 91% among the 50 patients with low and 54% and 45% in the 20 patients with high BL-ME-S (both P<0.0001). These data were validated in 113 patients with only BL-ME data: 3-yr OS and EFS were 90% and 85% among the 89 patients with low as opposed to 70% and 55% among the 14 patients with high BL-ME-S (p=0.001, p=0.002). TT3 survival was independently significantly affected by PB-ME-S (OS: HR=12.74, p=0.002; EFS: HR=14.32, p<0.001) and BL-ME-S (EFS: HR=3.10, p=0.045), whereas the univariately significant role of BL-PC-S for both endpoints could not be confirmed on multivariate analysis. Conclusions: To our knowledge, this is the first report documenting a validated prognostic role of ME for cancer survival. Key genes shared by both PB-ME-S and BL-ME-S models are involved in endothelial and mesenchymal stem-cell signaling, the details of which will be reported at the meeting.

[Table: see text]

Prognostic implications of comprehensive imaging with PET-CT, MRI, and X-rays and their biological and molecular correlates in multiple myeloma (MM) treated with total therapy 3 (TT3)

8532

Background: PET and MRI can reveal intramedullary focal lesions (FL) before osteolysis is detected on metastatic bone survey (MBS). Diagnostic merits, biological/molecular correlates, and outcome implications of the imaging techniques were prospectively and serially evaluated in 269 of 303 newly-diagnosed patients receiving TT3. Methods: Examined were FL number identified by PET (FDG-FL), CT portion of PET (CT-FL), MRI (MRI-FL), and MBS (MBS-FL); additionally, max-SUV of FL (SUV-FL), diffusely-involved bone marrow (SUV-DI), and extramedullary disease (EMD) on PET-CT. Results were compared, laboratory correlates examined (eg: gene expression profiling [GEP]-derived risk, molecular subgroups), and outcome implications determined. Results: Comparing anatomic sites, PET detected the highest mean FL followed by MRI and MBS (p<0.0001). Univariately significant implications on overall and event-free survival (OS, EFS) of FDG-FL, MBS-FL, and EMD may be explained by their link to other prognostic variables. Applying tertile frequency distributions of all imaging parameters, significant associations were seen for B2M with MBS-FL, FDG-FL, SUV-DI; CRP with MRI-FL, FDG-FL, CT-FL; GEP-defined high-risk with MRI-FL, FDG-FL, MBS-FL, SUV-FL; GEP low bone (LB) disease with MRI-FL, FDG-FL, SUV-FL; GEP Proliferation (PR) subgroup with MRI-FL, FDG-FL, MBS-FL, CT-FL. Yet on multivariate analysis, OS was independently adversely affected by both SUV-FL (>11) (p=0.001) and MRI >23 (p=0.043) in addition to cytogenetic abnormalities (CA) (p=0.005), B2M (>5.5mg/L) (p=0.005), and LDH ((ULN) (p=0.017). Even with GEP-defined high-risk (p=0.008), SUV-FL (>11) (p=0.009) retained independent significance in addition to CA (P<0.001) and CRP (>8mg/L) (p=0.020). Conclusions: This first prospective comprehensive imaging approach to MM showed that high SUV-FL had significant survival implications even after adjusting for powerful prognostic variables, especially GEP-defined risk. Multifaceted correlations of imaging variables also with molecular features of MM underscore the key role of bone (“soil”) for MM (“seed”) development and progression.

[Table: see text]

Gene expression profiling (GEP) of cd 138-purified plasma cells (pc) in previously treated multiple myeloma (PTMM): Validating prognostic models developed in newly diagnosed MM (NDMM)

8598

Background: We have previously reported on the strong discriminatory power in NDMM of GEP-derived 70-gene risk in CD138-purified plasma-cells developed in 351 patients enrolled in TT2 and validated in 441 patients enrolled in two TT3 trials and in PTMM treated with single agent high-dose dexamethasone or bortezomib. Here we report on the overall survival outcomes in 137 patients with PTMM. Methods: Treatment regimens included further autotransplantation and novel agent combinations. The purpose of the investigation was to determine whether PTMM OS was also governed by GEP features, such as high-risk (HR) score, proliferation score (PS), proliferation (PR) molecular subgroup, gain/amplification of chromosome 1q (amp1q) and deletion of the short arm (del1p) and TP53 deletion. Results: Compared with NDMM, PTMM was characterized by greater proportions with HR (32% v 16%, p<0.001), PS (20% v 10%, p=0.002) and PR (24% v 11%, p < 0.001); no difference was observed for TP53 deletion (21% v 30%, p=0.11); amp1q/del1p was more common in PTMM (17% v 9%, p=0.01). OS was 60% at 8yr in NDMM compared to a median of only 2.4yr in PTMM. According to HR, 4-yr OS estimates were 80% for LR v 37% for HR in NDMM (p<0.0001) and 52% for LR v 24% for HR in PTMM (p<0.01). On multivariate analysis of both standard prognostic factors and GEP HR, OS in PTMM was adversely affected by HR status (HR=2.00, p=0.047) and albumin <3.5g/dL (HR=2.66, P=0.013), accounting for a cumulative R2 value of 20%. Conclusions: GEP-derived high-risk features are more prevalent in PTMM relative to NDMM in terms of HR, PS, PR and amp1q/del1p status. As in NDMM, HR status confers poor OS in PTMM. Consistent with serial sampling where LR to HR transformation routinely occurs, these data support the concept that HR in PTMM is derived from clonal evolution. Treatment strategies that presume the existence of underlying HR cells even in LR disease, should be pursued.

[Table: see text]

Benefit of thalidomide (THAL) in total therapy 2 (TT2) of multiple myeloma (MM) exhibiting both cytogenetic abnormalities (CA) and low-risk (LR) by gene expression profiling (GEP)

8590

Background: We recently reported an update of TT2 and observed an unexpected preferential benefit from THAL for OS in the subgroup of patients with CA (Blood, 2008). We now re-examined these results with further follow-up of 81 months in the context of GEP-defined risk. Methods: OS and EFS were examined in the 668 patients enrolled in TT2 according to treatment arm, CA status and by GEP risk status. Results: Median overall and event-free survival (OS, EFS) are 9yr and 5yr, with a significant benefit from THAL v the control arm (p=0.04, p=0.0004). We confirmed the ongoing unique survival benefit of THAL in the CA group with 6-yr OS estimates of 53% v 35% (p<0.001), while patients not exhibiting CA had similar OS of 70% and 68%. EFS was superior with THAL regardless of CA status, 56% v 45% without CA (p=0.02) and 38% v 20% with CA (p=0.008). With respect to GEP, THAL benefited the LR group with 6-yr OS/EFS rates of 73%/56% v 63%/36% without THAL (p=0.10/p=0.002); the corresponding data for high-risk (HR) patients showed OS/EFS with THAL of 35%/19% v 15%/10% without THAL (p=0.36/p=0.43). When examined in the context of both GEP and CA, THAL only benefited the 33 patients with both CA and LR with 6-yr OS of 72% v 37% among the 47 without THAL (p=0.003). For the remaining subgroups (CA/HR; no CA/LR, no CA/HR), the addition of THAL did not impact OS. Conclusions: The unique benefit of THAL to the CA/LR subgroup may be linked to its greater efficacy in proliferative MM (enabling CA detection) that can only be sustained in the LR (lacking amplification of 1q21?) but not in the HR subset. The concomitant examinations of MM genetics by both GEP and cytogenetics enabled the discovery of this subgroup-specific treatment benefit. Data on TT3 with the addition of bortezomib will be presented in the context of the CA/GEP-risk scenario.

[Table: see text]

Functional comparison of the binding of factor H short consensus repeat 6 (SCR 6) to factor H binding protein from Neisseria meningitidis and the binding of factor H SCR 18 to 20 to Neisseria gonorrhoeae porin

Both Neisseria meningitidis and Neisseria gonorrhoeae recruit the alternative pathway complement inhibitory protein factor H (fH) to their surfaces to evade complement-dependent killing. Meningococci bind fH via fH binding protein (fHbp), a surface-exposed lipoprotein that is subdivided into three variant families based on one classification scheme. Chimeric proteins that comprise contiguous domains of fH fused to murine Fc were used to localize the binding site for all three fHbp variants on fH to short consensus repeat 6 (SCR 6). As expected, fH-like protein 1 (FHL-1), which contains fH SCR 6, also bound to fHbp-expressing meningococci. Using site-directed mutagenesis, we identified histidine 337 and histidine 371 in SCR 6 as important for binding to fHbp. These findings may provide the molecular basis for recent observations that demonstrated human-specific fH binding to meningococci. Differences in the interactions of fHbp variants with SCR 6 were evident. Gonococci bind fH via their porin (Por) molecules (PorB.1A or PorB.1B); sialylation of lipooligosaccharide enhances fH binding. Both sialylated PorB.1B- and (unsialylated) PorB.1A-bearing gonococci bind fH through SCR 18 to 20; PorB.1A can also bind SCR 6, but only weakly, as evidenced by a low level of binding of FHL-1 relative to that of fH. Using isogenic strains expressing either meningococcal fHbp or gonococcal PorB.1B, we discovered that strains expressing gonococcal PorB.1B in the presence of sialylated lipooligosaccharide bound more fH, more effectively limited C3 deposition, and were more serum resistant than their isogenic counterparts expressing fHbp. Differences in fH binding to these two related pathogens may be important for modulating their individual responses to host immune attack.

VTD combination therapy with bortezomib-thalidomide-dexamethasone is highly effective in advanced and refractory multiple myeloma

Bortezomib (V) was combined with thalidomide (T) and dexamethasone (D) in a phase I/II trial to determine dose-limiting toxicities (DLT's) and clinical activity of the VTD regimen in 85 patients with advanced and refractory myeloma. The starting dose of V was 1.0 mg/m(2) (days 1, 4, 8, 11, every 21 day) with T added from cycle 2 at 50 mg/day, with 50 mg increments per 10 patient cohorts, to a maximum dose of 200 mg. In the absence of DLT's, the same reiteration of T dose increases was applied with a higher dose of V=1.3 mg/m(2). D was added with cycle 4 in the absence of partial response (PR). Ninety-two percent had prior autotransplants, 74% had prior T and 76% abnormal cytogenetics. MTD was reached at V=1.3 mg/m(2) and T=150 mg. Minor response (MR) was recorded in 79%, and 63% achieved PR including 22% who qualified for near-complete remission. At 4 years, 6% remain event-free and 23% alive. Both OS and EFS were significantly longer in the absence of prior T exposure and when at least MR status was attained. The MMSET/FGFR3 molecular subtype was prognostically favorable, a finding since reported for a VTD-incorporating tandem transplant trial (Total Therapy 3) for untreated patients with myeloma (BJH 2008).

High CR and near-CR rate with bortezomib incorporated into up-front therapy of multiple myeloma with tandem transplants

7519

Background: Tandem autotransplants have increased complete response (CR) rates and extended event-free survival (EFS) and overall survival (OS) in multiple myeloma (MM). Because of its remarkable efficacy in end-stage disease and to further increase CR and thereby improving EFS and OS, bortezomib (Velcade, V) was incorporated into Total Therapy 3 (TT3), both with DT-PACE combination chemotherapy (dex, thalidomide, cis-platin, adriamycin, cyclophosphamide, etoposide) as induction prior to and consolidation after transplant. Methods: TT3 has accrued 247 of a target population of 300 patients; median follow-up is 16 months. Twenty-seven percent of patients were 65 yr and older; cytogenetic abnormalities (CA) were present in 31% and inter-phase FISH-based deletion 13 in 42%. Results: Median times to 1st and 2nd transplants were 3 mo and 5 mo, with projected completion rates of 95% and 82%. The cumulative frequency of CR plus near-CR was 50% at 6 mo, 75% at 12 mo, reaching 80% at 18 mo. Blood stem cells were readily procured, yielding ≥20 million CD34 cells/kg in > 95%. At 12 mo, 91% are alive and 89% event-free. Relapse has occurred in 29 patients, whose distinguishing features included age ≥ 65 yr (48% vs 24%, p = .005), abnormal cytogenetics (CA, 48% vs. 29%, p = .03) and LDH > ULN (48% vs 23%, p = .004). Among 21 deaths, baseline features were: creatinine >4 mg/dL in 4; age ≥ 65 yr in 11; PS > 3 in 5 and PS > 2 in 4; CRP > 10 mg/L in 9 patients. Conclusions: Introducing V in TT3 as part of combination chemotherapy is safe, permits robust stem cell collection and induces remarkably high CR plus near-CR rates. High-risk MM features such as CA and LDH, defined in Total Therapies 1 and 2, also appeared detrimental with TT3.

[Table: see text]

Gene expression fingerprint of uterine serous papillary carcinoma: identification of novel molecular markers for uterine serous cancer diagnosis and therapy

Uterine serous papillary cancer (USPC) represents a rare but highly aggressive variant of endometrial cancer, the most common gynecologic tumour in women. We used oligonucleotide microarrays that interrogate the expression of some 10 000 known genes to profile 10 highly purified primary USPC cultures and five normal endometrial cells (NEC). We report that unsupervised analysis of mRNA fingerprints readily distinguished USPC from normal endometrial epithelial cells and identified 139 and 390 genes that exhibited >5-fold upregulation and downregulation, respectively, in primary USPC when compared to NEC. Many of the genes upregulated in USPC were found to represent adhesion molecules, secreted proteins and oncogenes, such as L1 cell adhesion molecule, claudin-3 and claudin-4, kallikrein 6 (protease M) and kallikrein 10 (NES1), interleukin-6 and c-erbB2. Downregulated genes in USPC included SEMACAP3, ras homolog gene family, member I (ARHI), and differentially downregulated in ovarian carcinoma gene 1. Quantitative RT-PCR was used to validate differences in gene expression between USPC and NEC for several of these genes. Owing to its potential as a novel therapeutic marker, expression of the high-affinity epithelial receptor for Clostridium perfringens enterotoxin (CPE) claudin-4 was further validated through immunohistochemical analysis of formalin-fixed paraffin-embedded specimens from which the primary USPC cultures were obtained, as well as an independent set of archival USPC specimens. Finally, the sensitivity of primary USPC to the administration of scalar doses of CPE in vitro was also demonstrated. Our results highlight the novel molecular features of USPC and provide a foundation for the development of new type-specific therapies against this highly aggressive variant of endometrial cancer.

Cure of myeloma: hype or reality?

High-dose treatment (HDT) with autologous stem cell transplant(s) (ASCT) improved survival, when compared to standard treatment, in multiple myeloma patients. Although the superiority of HDT is clearly recognized by the medical community, what is less appreciated is the disproportionate benefit enjoyed (as a result of this approach) by various patient subgroups. As the clinical heterogeneity of myeloma can be currently traced to its underlying genetic features, prognostically different patient groups can be identified largely based on the presence of adverse cytogenetic abnormalities and high serum levels of lactate dehydrogenase at baseline (high-risk features). While HDT applied to high-risk patients leads to modest survival gains, the same treatment, as the backbone of a comprehensive approach, can be curative in a minority of low-risk patients. A third group of low-risk patients will enjoy rather prolonged (10-year) survival, interrupted, however, by responsive relapses. In a manner analogous to follicular lymphoma, this latter group may transform to a more aggressive disease, characterized by the new acquisition of adverse cytogenetic abnormalities. Improving the complete response rate in these patients, by integrating newer therapeutic agents, may increase their cure rate. Currently non-myeloablative, allogeneic transplants (and possibly proteasome inhibitors) are the most promising approaches for high-risk patients.

Discrimination between uterine serous papillary carcinomas and ovarian serous papillary tumours by gene expression profiling

High-grade ovarian serous papillary cancer (OSPC) and uterine serous papillary carcinoma (USPC) represent two histologically similar malignancies characterised by markedly different biological behavior and response to chemotherapy. Understanding the molecular basis of these differences may significantly refine differential diagnosis and management, and may lead to the development of novel, more specific and more effective treatment modalities for OSPC and USPC. We used an oligonucleotide microarray with probe sets complementary to >10 000 human genes to determine whether patterns of gene expression may differentiate OSPC from USPC. Hierarchical cluster analysis of gene expression in OSPC and USPC identified 116 genes that exhibited >two-fold differences (P<0.05) and that readily distinguished OSPC from USPC. Plasminogen activator inhibitor (PAI-2) was the most highly overexpressed gene in OSPC when compared to USPC, while c-erbB2 was the most strikingly overexpressed gene in USPC when compared to OSPC. Overexpression of the c-erbB2 gene and its expression product (i.e., HER-2/neu receptor) was validated by quantitative RT-PCR as well as by flow cytometry on primary USPC and OSPC, respectively. Immunohistochemical staining of serous tumour samples from which primary OSPC and USPC cultures were derived as well as from an independent set of 20 clinical tissue samples (i.e., 10 OSPC and 10 USPC) further confirmed HER-2/neu as a novel molecular diagnostic and therapeutic marker for USPC. Gene expression fingerprints have the potential to predict the anatomical site of tumour origin and readily identify the biologically more aggressive USPC from OSPC. A therapeutic strategy targeting HER-2/neu may be beneficial in patients harbouring chemotherapy-resistant USPC.