Don L. Siegel

NY-ESO-1-specific TCR-engineered T cells mediate sustained antigen-specific antitumor effects in myeloma

Despite recent therapeutic advances, multiple myeloma (MM) remains largely incurable. Here we report results of a phase I/II trial to evaluate the safety and activity of autologous T cells engineered to express an affinity-enhanced T cell receptor (TCR) recognizing a naturally processed peptide shared by the cancer-testis antigens NY-ESO-1 and LAGE-1. Twenty patients with antigen-positive MM received an average 2.4 × 109 engineered T cells 2 d after autologous stem cell transplant. Infusions were well tolerated without clinically apparent cytokine-release syndrome, despite high IL-6 levels. Engineered T cells expanded, persisted, trafficked to marrow and exhibited a cytotoxic phenotype. Persistence of engineered T cells in blood was inversely associated with NY-ESO-1 levels in the marrow. Disease progression was associated with loss of T cell persistence or antigen escape, in accordance with the expected mechanism of action of the transferred T cells. Encouraging clinical responses were observed in 16 of 20 patients (80%) with advanced disease, with a median progression-free survival of 19.1 months. NY-ESO-1–LAGE-1 TCR–engineered T cells were safe, trafficked to marrow and showed extended persistence that correlated with clinical activity against antigen-positive myeloma.

Genetic and functional characterization of human pemphigus vulgaris monoclonal autoantibodies isolated by phage display

Pemphigus is a life-threatening blistering disorder of the skin and mucous membranes caused by pathogenic autoantibodies to desmosomal adhesion proteins desmoglein 3 (Dsg3) and Dsg1. Mechanisms of antibody pathogenicity are difficult to characterize using polyclonal patient sera. Using antibody phage display, we have isolated repertoires of human anti-Dsg mAbs as single-chain variable-region fragments (scFvs) from a patient with active mucocutaneous pemphigus vulgaris. ScFv mAbs demonstrated binding to Dsg3 or Dsg1 alone, or both Dsg3 and Dsg1. Inhibition ELISA showed that the epitopes defined by these scFvs are blocked by autoantibodies from multiple pemphigus patients. Injection of scFvs into neonatal mice identified 2 pathogenic scFvs that caused blisters histologically similar to those observed in pemphigus patients. Similarly, these 2 scFvs, but not others, induced cell sheet dissociation of cultured human keratinocytes, indicating that both pathogenic and nonpathogenic antibodies were isolated. Genetic analysis of these mAbs showed restricted patterns of heavy and light chain gene usage, which were distinct for scFvs with different desmoglein-binding specificities. Detailed characterization of these pemphigus mAbs should lead to a better understanding of the immunopathogenesis of disease and to more specifically targeted therapeutic approaches.

Isolation of cell surface-specific human monoclonal antibodies using phage display and magnetically-activated cell sorting: applications in immunohematology.

A method is described for the isolation of filamentous phage-displayed human monoclonal antibodies directed at unpurifiable cell surface-expressed molecules. To optimize the capture of antigen-specific phage and minimize the binding of irrelevant phage antibodies, a simultaneous positive and negative selection strategy is employed. Cells bearing the antigen of interest are pre-coated with magnetic beads and diluted into an excess of unmodified antigen-negative cells. Following incubation of the cell admixture with a Fab/phage library, the antigen-positive cell population is retrieved using magnetically-activated cell sorting and antigen-specific Fab/phage are eluted and propagated in bacterial culture. Utilizing this protocol with magnetically-labeled Rh(D)-positive and excess unlabeled Rh(D)-negative human red blood cells and a Fab/phage library constructed from human peripheral blood lymphocytes, dozens of unique clinically-useful gamma 1 kappa and gamma 1 lambda anti-Rh(D) antibodies were isolated from a single alloimmunized individual. This cell-surface selection method is readily adaptable for use in other systems, such as for the identification of putative tumor-specific antigens and provides a rapid (< 1 month), high-yield approach for isolating self-replicative antibody reagents directed at novel or conformationally-dependent cell-surface epitopes.

Second auto-SCT is safe and effective salvage therapy for relapsed multiple myeloma.

Therapeutic options for patients with multiple myeloma whose disease has relapsed after a prior auto-SCT include novel biologic therapies, traditional chemotherapy or a second transplant, with no clear standard of care. Few published studies address the safety and efficacy of a second auto-SCT for relapsed disease. We reviewed the Abramson Cancer Center experience with salvage auto-SCT for relapsed multiple myeloma. Forty-one patients had received a salvage auto-SCT at our institution; the median time between transplants was 37 months (range 3–91). The overall response rate in assessable patients was 55%, and treatment-related mortality was 7%. With a median follow-up time of 15 months, the median PFS was 8.5 months and the median overall survival (OS) was 20.7 months. In a multivariate analysis of OS, independent prognostic factors were ⩾5 prior lines of therapy and time to progression after initial auto-SCT of ⩽12 months. We conclude that in well-selected patients, salvage auto-SCT is safe and effective for relapsed myeloma.

Prognostic value of FDG-PET scan imaging in lymphoma patients undergoing autologous stem cell transplantation

We conducted a retrospective analysis of 50 lymphoma patients (Hodgkins disease and non-Hodgkins lymphoma) who had an 18F-fluoro-deoxyglucose positron emission tomography (FDG-PET) scan after at least two cycles of salvage chemotherapy and before autologous stem cell transplantation (ASCT) at our institution. The patients were categorized into FDG-PET negative (N=32) and positive (N=18) groups. The median follow-up after ASCT was 19 months (range: 3–59). In the FDG-PET-negative group, the median progression-free survival (PFS) was 19 months (range: 2–59) with 15 (54%) patients without progression at 12 months after ASCT. The median overall survival (OS) for this group was not reached. In the FDG-PET-positive group, the median PFS was 5 months (range: 1–19) with only one (7%) patient without progression at 12 months after ASCT. The median OS was 19 months (range: 1–34). In the FDG-PET-negative group, chemotherapy-resistant patients by CT-based criteria had a comparable outcome to those with chemotherapy-sensitive disease. A positive FDG-PET scan after salvage chemotherapy and prior ASCT indicates an extremely poor chance of durable response after ASCT.

A model system for detection and isolation of a tumor cell surface antigen using antibody phage display

To establish a screening procedure for tumor cell-surface reactive Fabs, we used a model antigen/antibody system including the epidermal growth factor receptor (EGF-R) and the anti-EGF-R monoclonal antibody 425. The 425 Fab was displayed on the surface of M13 filamentous phage. In a screening assay for 425 phage binding to tumor cell surfaces, biotinylated 425-phage bound specifically to EGF-R-positive A431 epidermoid carcinoma cells and not to K562 non-expressor erythroleukemia cells. With a model library, the sensitivity of phage enrichment by phage binding to cell surfaces was one 425-phage in 20,000 unrelated phages after 4 rounds of panning on A431 cells. In a phage tissue screening assay, 425-phage, but not unrelated phage, bound specifically to melanoma cells expressing EGF-R. Epitope and idiotope specificity of 425-phage was demonstrated in phage competition assays, using as targets A431 cells and anti-idiotypic antibodies to monoclonal antibody 425, respectively. Finally, the EGF-R protein was directly isolated from A431 cell extracts, using biotinylated 425-phage. The data obtained with the 425 model library system demonstrate the usefulness of antibody phage display for the rapid identification and isolation of tumor or other disease-related cell surface antigens.

On the mechanism of staphylococcal protein A immunomodulation

From the Rheumatic Diseases Core Center, Department of Medicine, University of California at San Diego, La Jolla, California; and the Division of Transfusion Medicine, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania. Address reprint requests to: Don L. Siegel, PhD, MD, Division of Transfusion Medicine, Department of Pathology & Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104; e-mail: siegeld@mail.med.upenn.edu. Received for publication August 13, 2004; revision received August 31, 2004, and accepted August 31, 2004. TRANSFUSION 2005;45:274-280. C O M M E N T A R Y

Phage antibody display libraries: a powerful antibody discovery platform for immunotherapy

Abstract Phage display technology (PDT), a combinatorial screening approach, provides a molecular diversity tool for creating libraries of peptides/proteins and discovery of new recombinant therapeutics. Expression of proteins such as monoclonal antibodies (mAbs) on the surface of filamentous phage can permit the selection of high affinity and specificity therapeutic mAbs against virtually any target antigen. Using a number of diverse selection platforms (e.g. solid phase, solution phase, whole cell and in vivo biopannings), phage antibody libraries (PALs) from the start point provides great potential for the isolation of functional mAb fragments with diagnostic and/or therapeutic purposes. Given the pivotal role of PDT in the discovery of novel therapeutic/diagnostic mAbs, in the current review, we provide an overview on PALs and discuss their impact in the advancement of engineered mAbs.

Homologous regions of autoantibody heavy chain complementarity-determining region 3 (H-CDR3) in patients with pemphigus cause pathogenicity

Pemphigus is a life-threatening autoimmune disease in which antibodies specific for desmogleins (Dsgs) cause loss of keratinocyte cell adhesion and blisters. In order to understand how antibodies cause pathogenicity and whether there are commonalities among antibodies in different patients that could ultimately be used to target specific therapy against these antibodies, we characterized Dsg-specific mAbs cloned by phage display from 3 patients with pemphigus vulgaris and 2 with pemphigus foliaceus. Variable heavy chain gene usage was restricted, but similar genes were used for both pathogenic and nonpathogenic mAbs. However, the heavy chain complementarity-determining region 3 (H-CDR3) of most pathogenic, but not nonpathogenic, mAbs shared an amino acid consensus sequence. Randomization of the H-CDR3 and site-directed mutagenesis indicated that changes in this sequence could block pathogenicity but not necessarily binding. In addition, for 2 antibodies with longer H-CDR3s, a tryptophan was critical for pathogenicity but not binding, a result that is consistent with blocking the tryptophan acceptor site that is thought to be necessary for Dsg-mediated adhesion. These studies indicate that H-CDR3 is critical for pathogenicity of a human autoantibody, that a small region (even 1 amino acid) can mediate pathogenicity, and that pathogenicity can be uncoupled from binding in these antibodies.

Mechanisms of action of therapeutics in idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) is a common immune disorder caused by platelet-reactive autoantibodies. Antibody-coated platelets are cleared more rapidly from the circulation, often in the spleen, than they can be replaced by compensatory stimulation of platelet production in the bone marrow. In some patients, platelet production is depressed as well. ITP in adults does not generally remit spontaneously, and most patients require treatment to prevent bleeding at one time or another. Therapy with corticosteroids, danazol, intravenous immune globulin, anti-D antibody, and several other agents inhibits clearance of the antibody-coated platelets but is rarely curative. Most patients will sustain a hemostatic response after splenectomy, although relapses may occur at any time. Patients may be more responsive to these same modalities after splenectomy, but treatment with an immunosuppressant that inhibits T- and B-cell function and cooperation, including azathioprine, cyclophosphamide, cyclosporine, mycophenolate mofetil, or anti-CD20, may be required. Antiviral therapy is useful in patients with HIV or hepatitis C infection, but no consensus has been reached as to the efficacy of antibiotics to eradicate Helicobacter pylori. Promising results have been seen in several patients treated with a modified thrombopoietin. It may be possible to design therapeutics that exploit the apparent restricted immunoglobulin gene usage by antiplatelet antibodies, perhaps in the form of engineered anti-idiotypic antibodies or other compounds that specifically target autoantibody-producing B cells. Rationale therapy awaits a more thorough understanding of autoantibody production.