Rituximab Elicitation of Tumor Specific T-cell Responses in Lymphoma Patients

描述(申请人提供)：利妥昔单抗是一种针对CD20的嵌合单抗，已在滤泡性淋巴瘤(FL)患者中显示出显著的治疗活性，但其确切作用机制尚未完全确定。虽然对CD20+FL细胞的杀伤作用，无论是通过补体依赖的细胞溶解，抗体依赖的细胞毒作用，还是直接诱导细胞凋亡，都可能有助于其疗效，但这些机制不太可能是唯一的作用机制，因为：(A)在最后一剂利妥昔单抗治疗后，临床和分子反应可能会持续数月；(B)利妥昔单抗第二次反应的中位数持续时间长于第一次反应，这些临床结果不能仅用上述机制来解释。利妥昔单抗诱导的FL细胞死亡预计会导致肿瘤抗原的释放，例如来自FL相关免疫球蛋白(Ig)重链(VH)和轻链(VL)可变区的抗原，以及尚未确定的肿瘤抗原，在促炎环境中。我们假设，利妥昔单抗诱导的淋巴瘤相关抗原的释放将激发细胞介导的淋巴瘤特异性免疫反应。我们将通过使用Elispot、Fluorispot、Lysipot和细胞内细胞因子流式细胞术检测新诊断的FL患者在利妥昔单抗治疗前后外周血和肿瘤侵袭性淋巴瘤特异性效应和/或记忆性CD4+和CD8+T细胞的存在来验证这一假设。我们还将检验这一假设的两个推论，即利妥昔单抗可引发活跃的淋巴瘤特异性细胞反应；(A)导致淋巴瘤特异性CD4+和CD8+T细胞的效应功能增强；以及(B)提供产生淋巴瘤特异性体液反应所需的必要T细胞帮助。Rituximab产生淋巴瘤特异性免疫反应的证明，以及对该反应的靶抗原的了解，将对我们如何以最佳方式治疗FL患者产生深远的影响。例如，它建议将利妥昔单抗与有望增强淋巴瘤特异性T细胞反应的药物，如GM-CSF、CpG寡核苷酸和抗CTLA-4单抗相结合，将具有潜在的临床益处。此外，这项研究的结果应该适用于其他恶性肿瘤的抗体治疗，因此，我们预计这些研究将导致设计新的治疗策略，以提高单抗治疗癌症的总体效果。滤泡性淋巴瘤(FL)是一种无痛但基本上无法治愈的疾病，然而，包括利妥昔单抗治疗在内的新疗法为患有这种疾病的患者提供了新的希望。利妥昔单抗是一种抗体，是一种针对淋巴瘤细胞上的另一种蛋白质，导致淋巴瘤细胞死亡的蛋白质，然而利妥昔单抗摧毁淋巴瘤细胞的确切机制(S)尚不清楚。我们的团队正在确定利妥昔单抗是否通过刺激患者自身的免疫系统来根除疾病而诱导淋巴瘤细胞死亡，因为更好地了解利妥昔单抗在淋巴瘤患者中的作用将使我们能够开发新的治疗方法，我们预计这将增加这种疾病患者的收益。

DESCRIPTION (provided by applicant): Rituximab, a chimeric monoclonal antibody directed against CD20, has shown significant therapeutic activity in patients with follicular lymphoma (FL), yet it's exact mechanism of action has not been completely defined. Although killing of the CD20+ FL cells, either through complement dependent cytolysis, antibody dependent cellular cytotoxicity or direct induction of apoptosis may contribute to its effectiveness, these mechanisms are unlikely to be the only mechanisms of action as; (a) the clinical and molecular responses to Rituximab may continue for months after the last dose of Rituximab and; (b) the median duration of the second response to Rituximab is longer than that of the first response, clinical findings that cannot be explained solely by the mechanisms described above. Rituximab induced FL cell death is expected to result in the release of tumor antigens, for example antigens derived from the variable regions of the heavy (VH) and light chains (VL) of the FL associated immunoglobulin (Ig), and also as yet undefined tumor antigens, in a pro-inflammatory environment. We hypothesize that the Rituximab induced release of lymphoma-associated antigens will provoke a cell-mediated lymphoma specific immune response. We will test this hypothesis by monitoring newly diagnosed FL patients for the presence of both peripheral blood and tumor infitrating lymphoma specific effector and/or memory CD4+ and CD8+ T-cells, before and after Rituximab treatment using Elispot, Fluorispot, Lysispot and intracellular cytokine flow cytometric assays. We will also test two corollaries of this hypothesis, being that a Rituximab elicited active lymphoma specific cellular response would; (a) result in an increase in the effector functions of both the lymphoma-specific CD4+ and CD8+ T cells; and (b) provide the necessary T- cell help required to generate lymphoma-specific humoral responses. The demonstration that Rituximab generates a lymphoma specific immune response, as well as the knowledge of the target antigens of the response would have profound implications as to how we optimally treat patients with FL. For example, it would suggest that combining Rituximab with agents which would be anticipated to augment the elicitation of a lymphoma specific T-cell response, such as GM-CSF, CpG oligonucleotides, and anti-CTLA-4 monoclonal antibodies, would be of potential clinical benefit. In addition, the results of this study should be applicable to antibody therapy of other malignancies, and as such, we anticipate that these studies will lead to novel treatment strategies designed to enhance the effectiveness of monoclonal antibody therapy for cancer in general. Follicular lymphoma (FL) is an indolent, but essentially incurable disease, however new treatments, including Rituximab therapy, are offering new hope for patients suffering with this disease. Rituximab is an antibody, which is a protein that targets another protein on the lymphoma cell, resulting in lymphoma cell death, however the exact mechanism(s) by which Rituximab destroys lymphoma cells is not yet clearly defined. Our group is determining whether Rituximab induces lymphoma cell death by stimulating the patient's own immune system to eradicate the disease, as a better understanding of how Rituximab works in patients with lymphoma will allow us to develop new approaches to treatment that we anticipate will lead to increased benefit for patients with this disease.