Targeting the proteasome to overcome therapy resistance in B-NHL

描述（由申请人提供）：拟议研究的长期目标是确定治疗复发性或难治性B细胞非霍奇金淋巴瘤（B-NHL）的新型有效治疗方法。尽管最近在B-NHL治疗设计方面取得了进展（即纳入利妥昔单抗），但超过一半的既往治疗患者随后在复发时表现出治疗耐药性疾病。拟议研究的具体目的是寻求了解硼替佐米（Velcade”）的作用机制，硼替佐米是一种蛋白酶体抑制剂，最近在治疗耐药性B细胞恶性肿瘤方面显示出了前景。硼替佐米的确切作用机制在很大程度上尚未确定，但在许多情况下可能涉及通过细胞凋亡诱导细胞死亡。初步数据表明，硼替佐米可有效杀死几种化疗耐药的侵袭性B-NHL细胞系，以及患者淋巴瘤标本。有趣的是，硼替佐米证明了参与几种分子途径以促进细胞死亡的能力。在第一个具体目标中，将研究细胞凋亡和Bcl-2蛋白家族在调节治疗耐药B-NHL的硼替唑米介导的细胞死亡中的作用。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感兴趣，因为靶向细胞死亡的非凋亡机制才刚刚开始被认为是治疗。最后，在目标3中，我们将应用从实验室研究中获得的知识，进一步描述硼替佐米的治疗效果，并验证其在原发性淋巴瘤样本中的作用机制。每种难治性/耐药性淋巴瘤将通过DNA微阵列进行分类（合作者：L.施陶德德，NIH）鉴定为具有活化的B细胞（ABC）、生发中心B细胞（GCB）或其它基因型。这将允许直接比较具有不良预后（ABC）的DLBCL与具有一般较好结果（GCB）的DLBCL之间的每种独特蛋白酶体的活性，包括离体和（用硼替佐米）临床。最近完成的NCI Velcade-EPOCH II期临床试验的初步数据（PI：W。Wilson，NCI;合作研究者：M. Czuczman，RPCI）在复发性/难治性B细胞NHL患者中的研究表明，硼替佐米主要在“预后不良”ABC亚组中增加EPOCH的抗肿瘤活性，其次是其下调NF：B活性并导致淋巴瘤细胞中促凋亡潜力增加的能力。总体而言，拟定研究旨在揭示硼替佐米在克服耐药性B-NHL背景下的详细作用机制，同时为复发性/难治性DLBCL患者开发有效、毒性较小的新型免疫化疗挽救方案（即VDR）。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，我们将其纳入我们的实验设计。我们的研究结果将被用于未来B细胞淋巴瘤的循证蛋白酶体相关疗法的开发。公共卫生相关性：尽管在癌症治疗方面取得了显著进展，但治疗难治性疾病和治疗抗性的发展仍然是主要的临床问题和死亡原因。这对于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）。拟议的研究与这一问题直接相关，因为该研究的目标是确定治疗难治性B细胞淋巴瘤的新方法，并精确定义这些药物如何杀死对传统疗法有抵抗力的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.