Immunosuppressive PLGA TGF-ß1 Microparticles Induce Polyclonal and Antigen-Specific Regulatory T Cells for Local Immunomodulation of Allogeneic Islet Transplants.

Allogeneic islet transplantation is a promising cell-based therapy for Type 1 Diabetes (T1D). The long-term efficacy of this approach, however, is impaired by allorejection. Current clinical practice relies on long-term systemic immunosuppression, leading to severe adverse events. To avoid these detrimental effects, poly(lactic-co-glycolic acid) (PLGA) microparticles (MPs) were engineered for the localized and controlled release of immunomodulatory TGF-ß1. The in vitro co-incubation of TGF-ß1 releasing PLGA MPs with naïve CD4+ T cells resulted in the efficient generation of both polyclonal and antigen-specific induced regulatory T cells (iTregs) with robust immunosuppressive function. The co-transplantation of TGF-ß1 releasing PLGA MPs and Balb/c mouse islets within the extrahepatic epididymal fat pad (EFP) of diabetic C57BL/6J mice resulted in the prompt engraftment of the allogenic implants, supporting the compatibility of PLGA MPs and local TGF-ß1 release. The presence of the TGF-ß1-PLGA MPs, however, did not confer significant graft protection when compared to untreated controls, despite measurement of preserved insulin expression, reduced intra-islet CD3+ cells invasion, and elevated CD3+Foxp3+ T cells at the peri-transplantation site in long-term functioning grafts. Examination of the broader impacts of TGF-ß1/PLGA MPs on the host immune system implicated a localized nature of the immunomodulation with no observed systemic impacts. In summary, this approach establishes the feasibility of a local and modular microparticle delivery system for the immunomodulation of an extrahepatic implant site. This approach can be easily adapted to deliver larger doses or other agents, as well as multi-drug approaches, within the local graft microenvironment to prevent transplant rejection.

Phase II dose-finding study of balugrastim in breast cancer patients receiving myelosuppressive chemotherapy.

Balugrastim is a once-per-cycle, fixed-dose recombinant protein comprising human serum albumin and granulocyte colony-stimulating factor under development for prevention of severe neutropenia in cancer patients receiving myelosuppressive chemotherapy. This phase II, multicenter, active-controlled, dose-finding pilot study evaluated balugrastim safety and efficacy versus pegfilgrastim in breast cancer patients scheduled to receive myelosuppressive chemotherapy and investigated two doses with similar efficacy to pegfilgrastim for a subsequent phase III study. Patients received four cycles of doxorubicin/docetaxel chemotherapy and with each successive cycle were randomized sequentially to escalating doses of balugrastim [30 (n = 11), 40 (n = 21), or 50 mg (n = 20)] or a fixed dose of pegfilgrastim [6 mg (n = 26)] post-chemotherapy. Balugrastim doses were escalated as planned. The incidence of adverse events was similar among the balugrastim groups and between all balugrastim doses and pegfilgrastim. The most frequently reported adverse events were neutropenia, alopecia, and nausea. During cycle 1, severe neutropenia (absolute neutrophil count of <0.5 × 10(9)/L) occurred in 40, 67, and 50 % and febrile neutropenia occurred in 20.0, 9.5, and 10.0 % of patients receiving balugrastim 30, 40, and 50 mg, respectively; in patients receiving pegfilgrastim, 48 % experienced severe neutropenia and 8 % experienced febrile neutropenia. Duration of severe neutropenia (DSN) for each treatment group was 0.9, 1.6, 1.1, and 0.9 days, respectively. In the remaining three chemotherapy cycles, DSN was ≤1 day across all treatment groups. Balugrastim 50 mg was comparable to pegfilgrastim in terms of safety and overall efficacy in breast cancer patients receiving myelosuppressive chemotherapy.

The remarkable flexibility of the human antibody repertoire; isolation of over one thousand different antibodies to a single protein, BLyS.

It is well established that the humoral immune response can generate antibodies to many different antigens. The antibody diversity required to achieve this is believed to be substantial. However, the extent to which the immune repertoire can generate structural diversity against a single target antigen has never been addressed. Here, we have used phage display to demonstrate the extraordinary capacity of the human antibody repertoire. Over 1000 antibodies, all different in amino acid sequence, were generated to a single protein, B-lymphocyte stimulator (BLyS protein). This is a highly diverse panel of antibodies as exemplified by the extensive heavy and light chain germline usage: 42/49 functional heavy chain germlines and 19/33 V(lambda) and 13/35 V(kappa) light chain germlines were all represented in the panel of antibodies. Moreover, a high level of sequence diversity was observed in the V(H) CDR3 domains of these antibodies, with 568 different amino acid sequences identified. Thus we have demonstrated that specific recognition of a single antigen can be achieved from many different VDJ combinations, illustrating the remarkable problem-solving ability of the human immune repertoire. When studied in a biochemical assay, around 500 (40%) of these antibodies inhibited the binding of BLyS to its receptors on B-cell lines. The most potent antibodies inhibited BLyS binding with sub-nanomolar IC(50) values and with sub-nanomolar affinities. Such antibodies provide excellent choices as candidates for the treatment of BLyS-associated autoimmune diseases.