Targeting the proteasome to overcome therapy resistance in B-NHL

描述(由申请人提供)：拟议研究的一个长期目标是确定治疗复发或难治性B细胞性非霍奇金淋巴瘤(B-NHL)的新的有效治疗方法。尽管最近在治疗B-NHL的设计中取得了进展(即纳入了利妥昔单抗)，但超过一半以前接受过治疗的患者在复发时随后表现出耐药疾病。这项拟议研究的具体目的是试图了解Bortezomib(VELCADE)的作用机制(S)，这是一种蛋白酶体抑制剂，最近在治疗耐药B细胞恶性肿瘤方面显示出良好的前景。Bortezomib的确切作用机制(S)在很大程度上仍不清楚，但在许多情况下可能涉及通过凋亡诱导细胞死亡。初步数据表明，Bortezomib在杀死几种耐化疗的侵袭性B-NHL细胞株以及患者淋巴瘤标本方面是有效的。有趣的是，Bortezomib展示了参与多个分子途径促进细胞死亡的能力。在第一个特定目标中，我们将研究细胞凋亡和Bcl2蛋白家族在调节Bortezomib介导的耐药B-NHL细胞死亡中的作用。在第二个目标中，将探索两种额外的细胞死亡模式--自噬和坏死--的潜在作用。从这一目标获得的结果预计将特别令人感兴趣，因为针对细胞死亡的非凋亡机制才刚刚开始被考虑用于治疗。最后，在目标3中，我们将应用从实验室研究中获得的知识来进一步描述Bortezomib的治疗效果，并在原发淋巴瘤样本中验证其作用机制(S)。根据DNA微阵列(合作者：L.Staudt，NIH)，每个难治性/耐药淋巴瘤将被分类为具有激活的B细胞(ABC)、生发中心B细胞(GCB)或其他基因。这将允许在预后较差的DLBCL(ABC)和预后一般较好的DLBCL(GCB)之间，直接比较每个独特的蛋白酶体的活性，包括体外和临床(使用Bortezomib)。最近完成的第二阶段NCI VELCADE-EPOCH临床试验(PI：W.Wilson，NCI；联合研究员：M.Chuuczman，RPCI)在复发性/难治性B细胞NHL患者中的初步数据表明，Bortezomib主要在“预后不良”ABC亚组中增加了EPOCH的抗肿瘤活性，其次是它能够下调NF：B活性，并导致淋巴瘤细胞中促凋亡潜力的增加。总之，拟议的研究旨在揭示Bortezomib在克服耐药B-NHL方面的详细作用机制(S)，同时开发一种有效、毒性较低的新型免疫化疗挽救方案(即VDR)用于复发/难治性DLBCL患者。为了加强我们最初的提交，我们已经确定了三种具有独特作用机制的下一代蛋白酶体抑制剂，我们将把它们包括在我们的实验设计中。我们的研究结果将被用于未来基于证据的蛋白酶体抑制剂相关治疗B细胞淋巴瘤的开发中。公共卫生相关性：尽管在癌症治疗方面取得了显著进展，但难治性疾病和治疗耐药性的发展仍然是一个主要的临床问题和死亡原因。许多类型的癌症都是如此，包括B细胞非霍奇金淋巴瘤(B-NHL)。这项拟议的研究与这一问题直接相关，因为该研究的目标是寻找治疗难治性B细胞淋巴瘤的新方法，并准确定义这些药物如何杀死对传统疗法具有耐药性的B-NHL。

DESCRIPTION (provided by applicant): A long-range goal of the proposed research is to identify novel and effective therapeutic approaches for the treatment of relapsed or refractory B cell non-Hodgkin's lymphoma (B-NHL). Despite recent advances (i.e. incorporation of rituximab) in the design of treatment for B-NHL, greater than half of previously treated patients subsequently demonstrate therapy-resistant disease at the time of relapse. The specific aims of the proposed research seek to understand the mechanism(s)-of-action of bortezomib (Velcade"), a proteasome inhibitor that has shown recent promise in the treatment of therapy-resistant B cell malignancies. The precise mechanism(s)-of-action of bortezomib remains largely undefined, but in many cases likely involves the induction of cell death via apoptosis. Preliminary data indicate that bortezomib is effective at killing several chemotherapy-resistant aggressive B-NHL cell lines, as well as in patient lymphoma specimens. Interestingly, bortezomib demonstrates the capacity to engage several molecular pathways to promote cell death. In the first specific aim, a role for apoptosis and the Bcl-2 family of proteins in regulating bortezomib-mediated cell death of therapy resistant B-NHL will be investigated. In the second aim, a potential role for two additional modes of cell death, autophagy and necrosis, will be explored. The results obtained from this aim are expected to be of particular interest, as targeting non-apoptotic mechanisms of cell death are just beginning to be considered therapeutically. Finally, in aim 3, we will apply the knowledge gained from the laboratory studies to further delineate bortezomib's therapeutic efficacy and validate its mechanism(s)-of-action in primary lymphoma samples. Each refractory/resistant lymphoma will be categorized by DNA microarray (Collaborator: L. Staudt, NIH) as having an activated B cell (ABC), a germinal center B cell (GCB), or other genotype. This will allow direct comparison of each unique proteasome's activity, both ex vivo and (with bortezomib) clinically, between DLBCLs with poor prognosis (ABC) versus those with generally better outcomes (GCB). Preliminary data from a recently completed Phase II NCI Velcade-EPOCH clinical trial (PI: W. Wilson, NCI; Co-investigator: M. Czuczman, RPCI) in patients with relapsed/refractory B-cell NHL indicates that bortezomib increased EPOCH's anti-tumor activity primarily in the "poor prognosis" ABC subgroup secondary to its ability to down- modulate NF:B activity and lead to an increased pro-apoptotic potential in lymphoma cells. Collectively, the proposed studies are designed to reveal detailed mechanism(s)-of-action of bortezomib in the context of overcoming therapy-resistant B-NHL, and concurrently developing an effective, less toxic, novel immunochemotherapeutic salvage regimen (i.e. VDR) for patients with relapsed/refractory DLBCL. To strengthen our original submission, we have identified three next-generation proteasome inhibitors with unique mechanisms-of-action which we will include into our experimental design. Our research findings will be utilized in the development of future evidence-based proteasome inhibitor-associated therapies for B-cell lymphomas. PUBLIC HEALTH RELEVANCE: Despite remarkable advances in the treatment of cancer, therapy-refractory disease and development of therapy resistance remains a major clinical problem and cause of mortality. This is true for many types of cancer, including B-cell non-Hodgkin lymphoma (B-NHL). The proposed research is directly relevant to this problem, as the goals of the study are to identify novel ways to treat therapy-refractory B-cell lymphoma, and to precisely define how these agents kill B-NHL that are resistant to conventional therapies.