Abstract 301: Targeting the anti-apoptotic BCL-2 family protein provides an effective and precise therapeutic strategy for NHL
Authors: Luo Qiu-Yun , Yi Han-Jie , Yan Xiang-Lei , Qiu Miaozhen , Li Bao-Xia , Zhang Lin , Pan Wen-Tao , Yuan Lu-Ping , Liu Zhen-Yi , Fang Douglas D. , Zhai Yifan , Sun Jian , Yang Da-Jun 
Published: August 2018

Background: Despite advances in the treatment of non-Hodgkin's lymphoma (NHL), refractory NHL remains a major clinical challenge. The B-cell lymphoma protein-2 (BCL-2) family is frequently overexpressed in NHL, which is associated with poor prognosis by promoting cell growth and resistance to antitumorigenic agents. In this study, by using different BCL-2 family protein inhibitors, we aim to further classify the survival dependency of NHL for anti-apoptotic BCL-2 family members and explore novel approaches to rationally develop combination therapies by completely blocking the activity of the Bcl-2 family proteins.

Methods: Cell viability was determined by CCK-8 assay. Apoptotic activity was confirmed by Annexin V-propidium iodide (PI) apoptosis detection, Western blot analysis and mitochondrial membrane potentials detection analysis. In vivo, NHL xenograft models were established to analyze the antitumor effect of the BCL-2 family protein inhibitors.

Results: We evaluated the inhibitory effect of of Bcl-2 targeted inhibitors and synergy in combination with other molecular targeted agents in NHL. While those NHL cell lines with only high levels of BCL-2 protein are sensitive to Bcl-2 selective inhibitor, the dual Bcl-2/Bcl-xL inhibitor APG-1252 and its active metabolite APG-1252-M1 potently induced mitochondria-dependent apoptosis in NHL cell lines that possess high expression of both BCL-2 and BCL-XL proteins. After the treatment of APG-1252-M1, apoptosis including caspase-3 activation, PARP cleavage, and mitochondrial membrane potentials change was observed rapidly within four hours. We further demonstrated that APG-1252-M1 showed synergistic effects with Bruton's tyrosine kinase (BTK) inhibitor ibrutinib in those sensitive cell lines by modulating STAT3 signaling pathways. However, cell lines harboring high expression of anti-apoptotic protein MCL-1 were resistant to APG-1252-M1. Furthermore, we observed that APG-1252-M1 exhibited strong synergistic effect with dual PI3K/mTOR inhibitors NVP-BEZ235 in those resistant cell lines with high levels of Mcl-2 protein.

Conclusions: Taken together, our data provide an effective and precise therapeutic strategy for NHL through determining NHL addiction to anti-apoptotic BCL-2 family proteins, and then target-guided application of BCL-2 family inhibitors as a monotherapy or in combination with other molecular targeted agents to completely block the Bcl-2 family proteins, thus to restore the apoptotic cell death.

Citation Format: Qiu-Yun Luo, Han-Jie Yi, Xiang-Lei Yan, Miaozhen Qiu, Bao-Xia Li, Lin Zhang, Wen-Tao Pan, Lu-Ping Yuan, Zhen-Yi Liu, Douglas D. Fang, Yifan Zhai, Jian Sun, Da-Jun Yang. Targeting the anti-apoptotic BCL-2 family protein provides an effective and precise therapeutic strategy for NHL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 301.