Genome wide expression profiling of human peripheral blood mononuclear cells stimulated with BAY 50-4798, a novel T cell selective interleukin-2 analog.

BAY 50-4798, a novel, engineered form of interleukin (IL)-2, is a selective agonist for the high-affinity IL-2 receptor and induces the proliferation of activated human T cells with potency similar to recombinant IL-2 (rIL-2), but has reduced proliferative activity on natural killer cells and is associated with a diminished secondary cytokine cascade. In the current study, the transcriptional profiles of human peripheral blood mononuclear cells (PBMCs) stimulated in vitro with BAY 50-4798 and rIL-2 were compared using Affymetrix microarray technology in combination with Ingenuity Pathway Analysis (IPA) to determine whether there are quantitative or qualitative differences in the molecular networks activated by these IL-2 analogs. A total of 299 genes were differentially expressed in response to the two IL-2 analogs, with an increase in the number of differences over time. Consistent with the fact that BAY 50-4798 interacts with fewer forms of the IL-2 receptor than rIL-2 to activate fewer cell types, 169 genes were expressed at lower levels in PBMCs cultured with BAY 50-4798 compared with IL-2. These genes were mainly categorized as cytokines and chemokines, and were used to build multiple molecular interaction networks, the most significant of which centered around a subunit of NF-kappaB, which is known to play a pivotal role in inflammation, and was associated with cell death. Of the genes induced in response to BAY 50-4798, only 25% were expressed at lower levels than those induced by rIL-2. Moreover, despite its more selective receptor targeting compared with rIL-2, BAY 50-4798 caused higher levels of expression of 130 genes, which predominantly fell into categories associated with metabolism and transcription. We interpret these results as consistent with the expected transcriptional profile of a mutein engineered and demonstrated to have diminished inflammatory effects yet fully retain selected features of IL-2 activity. In addition to demonstrating that the responses to BAY 50-4798 are characterized by differential expression of genes known to be induced by IL-2, we report for the first time the induction of a significant number of genes not previously reported in the context of IL-2 biology.

Reduced secondary cytokine induction by BAY 50-4798, a high-affinity receptor-specific interleukin-2 analog.

Recombinant interleukin-2 (IL-2) (aldesleukin, Proleukin, Chiron, Emeryville, CA) is approved for treatment of cancer patients and under investigation in HIV-infected individuals. However, treatment with aldesleukin is associated with toxicity, which may be due to its elicitation of inflammatory mediators from cells that express the intermediate-affinity IL-2 receptor. BAY 50-4798, a novel IL-2 analog, is a selective agonist for the high-affinity receptor. It induces the proliferation of activated T cells with a potency similar to that of aldesleukin but has reduced activity on cells expressing the intermediate-affinity receptor. In the current study, we compared cytokine responses elicited in peripheral blood mononuclear cell (PBMC) cultures stimulated with BAY 50-4798 or aldesleukin. BAY 50-4798 induced approximately 5-fold lower mean levels of endogenous IL-2 than aldesleukin, and at least 50% lower levels of proinflammatory cytokines, such as tumor necrosis fctor-alpha (TNF-alpha), IL-1beta, IL-6, and interferon-gamma (IFN-gamma). Furthermore, statistically significant reductions in the levels of IL-5, IL-8, IL-10, IL-13, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were observed in response to BAY 50-4798. These findings increase our understanding of the biologic action of BAY 50-4798 and suggest a mechanism by which it may exhibit better safety than aldesleukin in humans.