The tactics of modern-day regulatory trials.

Fractures are an important public health problem affecting patients of all ages. Although most fractures heal quickly, some heal poorly and some do not heal at all. To achieve an optimal healing outcome, the standard of care for most fractures consists of reduction followed by immobilization, with a myriad of options regarding the approach to fracture-healing. Currently, biopharmaceutical companies are sponsoring research with regard to products that aim to enhance or accelerate fracture-healing; however, as there are no approved and marketed systemic therapies for fracture-healing, the development and commercialization process for such products will require close collaboration between industry, academia, and regulators to determine how to bring these products to market in the most efficient manner. The following manuscript provides a brief overview of the regulatory process in the United States for systemic therapies in fracture-healing and discusses key issues that may arise in connection with the regulatory approval of these novel investigational treatments.

Potent activity of soluble B7RP-1-Fc in therapy of murine tumors in syngeneic hosts.

We have characterized a receptor:ligand pair, ICOS:B7RP-1, that is structurally and functionally related to CD28:B7.1/2. We reported previously that B7RP-1 costimulates T cell proliferation and immune responses (Yoshinaga et al., Nature 1999;402:827-32; Guo et al., J Immunol 2001;166:5578-84; Yoshinaga et al., Int Immunol 2000;12:1439-47). We report that B7RP-1-Fc causes rejection or growth inhibition of Meth A, SA-1 and EMT6 tumors in syngeneic mice. Established Meth A tumors were rejected effectively with a single dose of B7RP-1-Fc, however, the treatment was less effective on larger tumors. Mice that rejected Meth A tumors previously by Day 30, also rejected a subsequent Meth A challenge on Day 60, without additional B7RP-1-Fc treatment, indicating a long-lived memory response. Tumor cells believed to be less immunogenic, such as P815 and EL-4 cells, were less responsive to this treatment. The EL-4 responsiveness to the B7RP-1-Fc treatment was enhanced, however, by pre-treatment of the mice with cyclophosphamide. As expected, T cells appeared to be targeted by B7RP-1-Fc treatment. Thus, the administration of soluble B7RP-1-Fc may have therapeutic value in generating or enhancing anti-tumor activity in a clinical setting.