RESUMO
Rituximab, a monoclonal antibody targeting CD20 on B cells, is currently used to treat many subtypes of B cell lymphomas. However, treatment is not curative and response rates are variable. Recombinant interleukin-21 (rIL-21) is a cytokine that enhances immune effector function and affects both primary and transformed B cell differentiation. We hypothesized that the combination of rIL-21 plus rituximab would be a more efficacious treatment for B cell malignancies than rituximab alone. We cultured human and cynomolgus monkey NK cells with rIL-21 and found that their activity was increased and proteins associated with antibody dependent cytotoxicity were up-regulated. Studies in cynomolgus monkeys modeled the effects of rIL-21 on rituximab activity against CD20 B cells. In these studies, rIL-21 activated innate immune effectors, increased ADCC and mobilized B cells into peripheral blood. When rIL-21 was combined with rituximab, deeper and more durable B cell depletion was observed. In another series of experiments, IL-21 was shown to have direct antiproliferative activity against a subset of human lymphoma cell lines, and combination of murine IL-21 with rituximab yielded significant survival benefits over either agent alone in xenogeneic mouse tumor models of disseminated lymphoma. Therefore, our results do suggest that the therapeutic efficacy of rituximab may be improved when used in combination with rIL-21.
Assuntos
Anticorpos Monoclonais Murinos/farmacologia , Antineoplásicos/farmacologia , Linfócitos B/citologia , Linfócitos B/efeitos dos fármacos , Interleucinas/farmacologia , Linfoma de Células B/tratamento farmacológico , Linfoma de Células B/imunologia , Animais , Anticorpos Monoclonais Murinos/uso terapêutico , Citotoxicidade Celular Dependente de Anticorpos/efeitos dos fármacos , Antineoplásicos/uso terapêutico , Linfócitos B/imunologia , Linhagem Celular Tumoral , Modelos Animais de Doenças , Sinergismo Farmacológico , Feminino , Humanos , Imunidade Inata/efeitos dos fármacos , Linfoma de Células B/patologia , Macaca fascicularis , Masculino , Camundongos , Rituximab , Análise de SobrevidaRESUMO
CD4(+) CD25(+) regulatory T cells are expanded in solid and hematological malignancies including chronic lymphocytic leukemia (CLL). Several cytokines and co-stimulatory molecules are required for generation, survival and maintenance of their suppressive effect. We and others have shown direct cytotoxic effect of the novel common gamma chain cytokine interleukin (IL)-21 on primary B cells from CLL patients. Since members of this family of cytokines are known to exhibit their effects on diverse immune cells, we have examined the effects of IL-21 on CLL patient derived regulatory T cell (Treg) induction, expansion and the inhibitory effect on natural killer cells in vitro. We demonstrate here the expression of IL-21 receptor in CD4(+)CD25(High) regulatory cells from CLL patients. In contrast to IL-2, the IL-21 cytokine failed to mediate expansion of regulatory T cells or induced expression of Foxp3 in CD4(+)CD25(Intermediate) or CD4(+)CD25(Dim/-) T cells in whole blood derived from CLL patients. Interestingly, in contrast to their differential effects on expansion of the CD4(+)CD25(+)Foxp3(+)T cells, IL-2 and IL-21 exhibited a redundant role in Treg mediated suppression of NK cell mediated antibody dependent cytotoxicity function. Given the infusion related toxicities and pro-survival effect of IL-2 in CLL, these studies provide a rationale to explore IL-21 as an alternate gamma chain cytokine in CLL therapy.
Assuntos
Interleucina-2/farmacologia , Interleucinas/farmacologia , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Leucemia Linfocítica Crônica de Células B/imunologia , Linfócitos T Reguladores/efeitos dos fármacos , Citotoxicidade Celular Dependente de Anticorpos/efeitos dos fármacos , Antígenos CD4/biossíntese , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Separação Celular , Citometria de Fluxo , Fatores de Transcrição Forkhead/biossíntese , Humanos , Subunidade alfa de Receptor de Interleucina-2/biossíntese , Células Matadoras Naturais/metabolismo , Células Matadoras Naturais/patologia , Leucemia Linfocítica Crônica de Células B/patologia , Receptores de Interleucina-21/imunologia , Receptores de Interleucina-21/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Linfócitos T Reguladores/patologiaRESUMO
Interleukin-21 (IL-21) is a recently identified gamma-chain receptor cytokine family member that promotes B-cell apoptosis as well as activation of innate immune system. Based on this, we hypothesized that IL-21 might enhance the apoptosis induced by fludarabine and rituximab and also play a role in augmenting immune-mediated clearance of the chronic lymphocytic leukemia (CLL) cells. Our studies demonstrate that the majority of CLL patients have surface IL-21 receptor-alpha, and its expression correlates with apoptosis, tyrosine phosphorylation of STAT1, and up-regulation of the proapoptotic BH3 domain protein BIM. IL-21-induced BIM up-regulation is critical for apoptosis because inhibition of BIM expression using small interfering RNA prevented IL-21-induced apoptosis. IL-21 treatment of CLL cells but not normal T cells with fludarabine or rituximab additively enhanced the direct cytotoxic effect of these therapies. In addition to its proapoptotic effect, IL-21 promoted STAT1 and STAT5 phosphorylation in natural killer cells with concurrent enhanced antibody-dependent cellular cytotoxicity against rituximab-coated CLL cells in vitro. These data provide justification for combination studies of IL-21 with fludarabine and rituximab in CLL and suggest that BIM up-regulation might serve as relevant pharmacodynamic end point to measure biologic effect of this cytokine in vivo.
Assuntos
Citotoxicidade Celular Dependente de Anticorpos , Proteínas Reguladoras de Apoptose/genética , Apoptose , Citotoxicidade Imunológica , Interleucinas/fisiologia , Proteínas de Membrana/genética , Proteínas Proto-Oncogênicas/genética , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais Murinos , Proteína 11 Semelhante a Bcl-2 , Humanos , Rituximab , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT5/metabolismo , Regulação para Cima/genética , Vidarabina/análogos & derivados , Vidarabina/farmacologiaRESUMO
Multiple myeloma (MM) is a progressive disease that is thought to result from multiple genetic insults to the precursor plasma cell that ultimately affords the tumor cell with proliferative potential despite its differentiated phenotype and resistance to undergoing apoptosis. Altered expression of antiapoptotic factors as well as growth factors have been described in a significant number of patients. However, the key regulatory elements that control myeloma development and progression remain largely undefined. Because of the knowledge that B-lymphocyte stimulator (BLyS), a tumor necrosis factor (TNF) family member shown to be critical for maintenance of normal B-cell development and homeostasis, promotes the survival of malignant B cells, we began a coordinated study of BLyS and its receptors in MM. All MM cells studied expressed one or more of 3 known receptors (B-cell maturation antigen [BCMA], transmembrane activator and CAML interactor [TACI], and B-cell activating factor receptor [BAFF-R]) for BLyS; however, the pattern of expression was variable. Additionally, we provide evidence that BLyS can modulate the proliferative capacity and survival of MM cells. Finally, we provide evidence that BLyS is expressed by MM cells and is present in the bone marrow of patients with MM. Expression of BCMA, TACI, and BAFF-R by MM taken together with the ability of BLyS to support MM cell growth and survival has exciting implications because they may be potential therapeutic targets.