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

描述（由申请人提供）：利妥昔单抗是一种针对CD 20的嵌合单克隆抗体，在滤泡性淋巴瘤（FL）患者中显示出显著的治疗活性，但其确切的作用机制尚未完全确定。尽管通过补体依赖性细胞溶解、抗体依赖性细胞毒性或直接诱导细胞凋亡杀死CD 20 + FL细胞可能有助于其有效性，但这些机制不太可能是唯一的作用机制，因为：（a）对利妥昔单抗的临床和分子应答可能在最后一剂利妥昔单抗后持续数月;（B）对利妥昔单抗的第二次应答的中位持续时间长于第一次应答的中位持续时间，不能仅通过上述机制解释的临床发现。预期利妥昔单抗诱导的FL细胞死亡导致肿瘤抗原的释放，例如来源于FL相关免疫球蛋白（IG）的重链（VH）和轻链（VL）可变区的抗原，以及在促炎环境中尚未确定的肿瘤抗原。我们假设利妥昔单抗诱导的淋巴瘤相关抗原的释放将引起细胞介导的淋巴瘤特异性免疫应答。我们将通过使用Elispot、Fluorispot、Lysispot和细胞内细胞因子流式细胞术测定在利妥昔单抗治疗前后监测新诊断的FL患者外周血和肿瘤浸润淋巴瘤特异性效应和/或记忆CD 4+和CD 8 + T细胞的存在来检验这一假设。我们还将测试该假设的两个推论，即利妥昔单抗引发活性淋巴瘤特异性细胞应答将：（a）导致淋巴瘤特异性CD 4+和CD 8 + T细胞的效应子功能增加;和（B）提供产生淋巴瘤特异性体液应答所需的必要T细胞帮助。利妥昔单抗产生淋巴瘤特异性免疫应答的证明以及应答的靶抗原的知识将对我们如何最佳地治疗FL患者具有深远的影响。例如，它将表明将利妥昔单抗与预期增强淋巴瘤特异性T细胞应答的激发的药剂（例如GM-CSF、CpG寡核苷酸、和抗CTLA-4单克隆抗体，将具有潜在的临床益处。此外，本研究的结果应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新的治疗策略，旨在提高单克隆抗体治疗癌症的有效性。滤泡性淋巴瘤（FL）是一种惰性，但基本上是不治之症，然而新的治疗方法，包括利妥昔单抗治疗，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，它是一种靶向淋巴瘤细胞上另一种蛋白质的蛋白质，导致淋巴瘤细胞死亡，然而利妥昔单抗破坏淋巴瘤细胞的确切机制尚未明确定义。我们的小组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诱导淋巴瘤细胞死亡，以根除疾病，因为更好地了解利妥昔单抗如何在淋巴瘤患者中发挥作用将使我们能够开发新的治疗方法，我们预计这将导致这种疾病患者的获益增加。

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.