Mouse immune thrombocytopenia is associated with Th1 bias and expression of activating Fcγ receptors

Recombinant Costimulatory Fusion Proteins as Functional Immunomodulators Enhance Antitumor Activity in Murine B16F10 Melanoma

Blocking inhibitory signaling and engaging stimulatory signaling have emerged as important therapeutic modalities for cancer immunotherapy. This study aimed to investigate immunomodulatory features of three recombinant costimulatory ligand proteins in a mouse model, which are extracellular domains of OX40-ligand (OX40L), 4-1BB-ligand (4-1BBL), or two domains in tandem, fused with the transmembrane domain of diphtheria toxin (DTT), named DTT-COS1, DTT-COS2, and DTT-COS12, respectively. In vitro study showed that DTT-COS1 and DTT-COS12 had immunological activity increasing the ratio of CD8/CD4 T cells. Treatments with DTT-COS1 and DTT-COS12 dramatically generated immune protection against the B16F10 tumor challenge in both prophylactic and therapeutic efficacy. Furthermore, regarding tumor microenvironment (TME) immunomodulation, DTT-COS1 treatment increased the proportion of CD4+ effector T cells (Teff) and decreased the expression of a suppressive cytokine. Meanwhile, DTT-COS12 reduced regulatory T cells (Treg) and improved the level of stimulatory cytokines. In addition, endogenous antibodies against OX40L/4-1BBL were generated, which may help with antitumor responses. Unexpectedly, DTT-COS2 lacked antitumor effects in vitro and in vivo. Importantly, serum analysis of liver-function associated factors and pro-inflammatory cytokines demonstrated that treatments were safe formulations in mice without signs of systemic toxicity. Remarkably, DTT-COS1 and DTT-COS12 are functional immunomodulators for mouse B16F10 melanoma, creating practical preclinical value in cancer immunotherapy.

Spotlight on romiplostim in the treatment of children with chronic immune thrombocytopenia: design, development, and potential place in therapy

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia. In approximately one-third of cases, the duration of thrombocytopenia will extend beyond 12 months consistent with a diagnosis of chronic ITP. Minor bleeding manifestations are common in chronic ITP while severe or life-threatening bleeding complications are uncommon. Moreover, spontaneous resolution occurs in the majority of children with chronic ITP necessitating treatment in only those children with ongoing bleeding manifestations or impairment in health-related quality of life (HRQOL). The characterization of thrombopoietin (TPO) and remarkable advancements in our understanding of the pathophysiology of ITP has led to the development of a new class of agents, the TPO-receptor agonists that have documented efficacy in the amelioration of thrombocytopenia and bleeding manifestations in chronic ITP. Romiplostim is a second-generation TPO-receptor agonist that has undergone limited evaluation in the treatment of chronic ITP in children. Evolving data suggest that romiplostim may be a safe and effective agent in the treatment of chronic ITP in children. Additional data are needed to confirm its ability to increase platelet counts, decrease bleeding manifestation, and improve the HRQOL of children and caregivers impacted by chronic ITP.