scholarly journals Daratumumab Resistant Natural Killer/T-Cell Lymphoma Exhibit an Addiction to the Exosome Biogenesis Pathway for Survival

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2256-2256
Author(s):  
Nurulhuda Mustafa ◽  
Muhamad Irfan Azaman ◽  
Wee-Joo Chng
Keyword(s):  
Protein Expression ◽  
Cell Line ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
Tumour Microenvironment ◽  
Resistant Cell ◽  
Natural Killer T Cell ◽  
Exosome Biogenesis ◽  
Killer T Cell ◽  
Resistant Cells

Abstract A phase 2 clinical trial has demonstrated that daratumumab monotherapy was safe and well tolerated in relapsed/refractory Natural Killer/T-Cell Lymphoma (NKTL). However, no patients achieved complete response, and duration of response was short. Similarly, in Multiple Myeloma (MM), while daratumumab based combinations are approved for front line treatment, responses are heterogeneous and development of treatment resistance inevitable. Therefore, elucidation of mechanisms which can overcome daratumumab resistance is essential for the optimization of therapeutic response in patients. To this end, 2 pairs of isogenic daratumumab resistant and sensitive models of NKTL were developed in vitro via sequential exposure of cell lines to increasing concentrations of daratumumab in the presence of complement serum. A 3rd model was also studied in vivo whereby long-term administration of daratumumab in mice identified a sub-group of tumors which stopped responding to treatment and began to rapidly enlarge ('Resistant') as compared to others which remained similar to or smaller ('Sensitive') than the tumour volume at the initiation of treatment. RNA sequencing was performed on these models and genes commonly upregulated or downregulated analyzed. Differential gene expression analysis highlighted an enrichment for the upregulation of genes involved in exosome biogenesis and secretion in both cell line and mouse-derived daratumumab resistant NKTL models. An additional daratumumab resistant model was developed in an MM cell line to further validate these findings and extend the study in an MM model. Immunoblotting of the 3 pairs of isogenic sensitive and resistant cell line models demonstrate that there is indeed an upregulation of proteins regulating exosomal biogenesis and secretion; Alix, TSG101 and Rab27b in the daratumumab resistant phenotype. This is associated with a concomitant increase in secreted exosomes levels in the tumour microenvironment. The size and quantification of extracellular vesicles (EV) secreted in the media were studied by nanoparticle tracking analysis. Extracellular vesicles ranged in the size of 70-150nM corroborating with the size of exosomes and nanoparticle quantification revealed a higher concentration of exosomes present in the tumour microenvironment of resistant cells as compared to sensitive cells. Subsequently, exosomes were purified via ultracentrifugation and protein expression analysis confirmed elevation of exosome markers CD63 and CD81. To study the role of exosomal-mediated mechanisms in the survival of daratumumab resistant cells, we treated isogenic models with neticonazole and ketoconazole (azoles) which have been identified as selective inhibitors of exosomal biogenesis in a drug repurposing study for advanced cancers. Interestingly, azole treatment demonstrated a selective and more effective suppression of tumour cell viability in daratumumab resistant than sensitive cell lines. Immunoblot analysis showed that azole treatment at identical concentrations resulted in a more extensive downregulation of Alix, Rab27b and CD81 protein expression in resistant than sensitive cells. Additionally, depletion of Alix and Rab27b protein expression via siRNA knockdown induced cell death confirming that daratumumab-resistant cell lines are dependent on exosomal-mediated pathways for survival. Current research is focused mainly on intrinsic or immune cell-mediated mechanisms of daratumumab resistance, but little is known regarding the effect of extrinsic components in the tumour microenvironment. We demonstrate that daratumumab resistant models exhibit a distinct upregulation of proteins mediating exosome biogenesis resulting in enhanced exosome secretion. Daratumumab resistant cells are targeted more efficaciously with exosome biogenesis inhibitors than sensitive counterparts thereby suggesting an addiction to exosome-mediated mechanisms of survival. This is further supported by gene silencing studies. In future, we aim to perform miRNA profiling of exosomes purified from the tumour microenvironment of isogenic daratumumab-resistant and sensitive cell line models as well as from bone marrow plasma of daratumumab treated patients. miRNA which are enriched in the exosomes of resistant phenotypes will be characterized, unique biomarkers of response identified and in depth mechanisms of resistance studied. Disclosures No relevant conflicts of interest to declare.

scholarly journals CD55 and CD59 Can Limit the Anti-Tumor Efficacy of Daratumumab in Natural Killer/T-Cell Lymphoma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1663-1663 ◽  
Author(s):  
Nurulhuda Mustafa ◽  
Adina Huey Fang Nee ◽  
Jing Yuan Chooi ◽  
Sabrina Hui Min Toh ◽  
Yan Ting Hee ◽  
...  
Keyword(s):  
T Cell ◽  
Natural Killer ◽  
Correlation Coefficient ◽  
Cell Lines ◽  
Research Funding ◽  
Cell Lymphoma ◽  
Resistant Cell ◽  
Natural Killer T Cell ◽  
Cd38 Expression ◽  
Killer T Cell

Abstract Complement-dependent cytotoxicity (CDC) is one of the major mechanisms mediating the anti-tumor efficacy of Daratumumab. We have previously demonstrated that a majority of Natural Killer/T- Cell Lymphoma (NKTL) patient samples express CD38 and Daratumumab is highly effective against NKTL cell lines expressing mid-high levels of CD38. In this report we show that subsequent testing in an NKTL mouse xenograft model confirms the potency of Daratumumab in vivo as evidenced by the inhibition in tumour progression and prolongation of mouse survival. When treatment was continued over a month, some tumors began to rapidly enlarge ('Resistant') while the rest remained similar or smaller ('Sensitive') than the tumour volume at the initiation of Daratumumab treatment. An mRNA analysis comparing 'Resistant' and 'Sensitive' tumors showed that while both tumours bore similar levels of CD38 expression, resistant tumours displayed an upregulation of complement inhibitory proteins (CIP), CD55 and CD59 but not CD46. This led us to hypothesize that CD59 and CD55 may play a critical role in Daratumumab-mediated CDC in NKTL. FACS analyses demonstrated that the number of membrane molecules of CD55 and CD59 appeared inversely correlated to Daratumumab-mediated CDC. A single CIP knockdown was first performed to delineate the role of each CIP. Silencing CD46 confirmed that it does not have any effect on CDC in NKTL. However, single knockdown of CD55 or CD59 was able to induce cytotoxicity in CDC-resistant cell line CD38midCD55hiCD59lo NKYS, and promote NKS1 CD38hiCD55hiCD59mid to further lysis. Both single and double knockdown of CD55 and CD59 could not enhance Daratumumab-induced CDC in CD38loCD55hiCD59hi HuT78 which recapitulates the importance of CD38 levels. Unexpectedly, the double knockdown did not sensitize CD38hiCD55hiCD59hi KMS12BM either. This led us to conjecture that it may be the ratio of CD38:CIPs which is predictive of response to Daratumumab than CD38 or CIPs alone. All-Trans Retinoic Acid (ATRA) binds the RARE element in CD38 gene leading to upregulation of mRNA and protein expression of CD38. We thus downregulated the expression of CIPs with siRNA followed by amplification of CD38 expression with ATRA in NKTL. This strategy resulted in a significant increase in the CD38:CIP ratio and induced almost a total lysis of NKS1 cells, as well as sensitised HuT78 to a massive amount of Daratumumab-mediated CDC. These experiments suggest that by increasing the CD38: CIP, ratio we can overcome resistance to Daratumumab-mediated CDC. To further statistically study this, a Spearman's rank correlation analyses was performed. The Spearman correlation coefficient shows that the number of surface molecules of CD38 positively correlates to CDC while that of CD55 displays an inverse correlation. CD46 and CD59 do not show any significant correlation. Notably, when correlating the CD38:CIP ratio instead to CDC, the CD38:CD46, CD38:CD55 and CD38:CD59 ratios always show a significant positive correlation coefficient. This suggests that the potential efficacy of Daratumumab can be predicted more accurately based on the ratio of CD38:CIP than any of the molecules alone. Detection of a low CD38:CIP ratio in patient samples could be a biomarker for potentially poorer response to Daratumumab treatment. Daratumumab-resistant NKTL cell lines are being developed in our lab and RNA sequencing comparing sensitive and resistance cells will be subsequently performed in order to gain further insights to mechanisms that may lead to resistance. Preliminary analyses on CD38 and CIP expression so far has shown that CD38 protein and mRNA expression are prominently downregulated in resistant cell lines while the level of CIPs remain similar or increased. The total outcomes of these studies will contribute valuable insights to clinical trials that currently involve Daratumumab treatment. Disclosures Zhou: Janssen R&D: Employment. Yang:Janssen R&D: Employment. Chng:Celgene: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Aslan: Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Merck: Research Funding.

scholarly journals HSP90 Inhibitor, 17-DMAG, Alone and in Combination with Lapatinib Attenuates Acquired Lapatinib-Resistance in ER-positive, HER2-Overexpressing Breast Cancer Cell Line

Cancers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2630
Author(s):  
Hye Jin Lee ◽  
Seungho Shin ◽  
Jinho Kang ◽  
Ki-Cheol Han ◽  
Yeul Hong Kim ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Proliferation ◽  
Protein Expression ◽  
Cell Line ◽  
Cell Lines ◽  
Xenograft Model ◽  
Resistant Cell ◽  
Bt474 Cell ◽  
Hsp90 Inhibitors ◽  
Her2 Breast Cancer

Lapatinib, a Human Epidermal growth factor Receptor 2 (HER2)-targeting therapy in HER2-overexpressing breast cancer, has been widely used clinically, but the prognosis is still poor because most patients acquire resistance. Therefore, we investigated mechanisms related to lapatinib resistance to evaluate new therapeutic targets that may overcome resistance. Lapatinib-resistant cell lines were established using SKBR3 and BT474 cells. We evaluated cell viability and cell signal changes, gene expression and protein changes. In the xenograft mouse model, anti-tumor effects were evaluated using drugs. Analysis of the protein interaction network in two resistant cell lines with different lapatinib resistance mechanisms showed that HSP90 protein was commonly increased. When Heat Shock Protein 90 (HSP90) inhibitors were administered alone to both resistant cell lines, cell proliferation and protein expression were effectively inhibited. However, inhibition of cell proliferation and protein expression with a combination of lapatinib and HSP90 inhibitors showed a more synergistic effect in the LR-BT474 cell line than the LR-SKBR3 cell line, and the same result was exhibited with the xenograft model. These results suggest that HSP90 inhibitors in patients with lapatinib-resistant Estrogen Receptor (ER) (+) HER2 (+) breast cancer are promising therapeutics for future clinical trials.

YM155 Exerts Potent Cytotoxic Activity Against Quiescent (G0/G1) Multiple Myeloma and Bortezomib Resistant Cells Via Inhibition of Mcl-1 and Survivin

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3023-3023
Author(s):  
Miyuki Ookura ◽  
Tatsuya Fujii ◽  
Shinji Kishi ◽  
Hiroko Shigemi ◽  
Naoko Hosono ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Protein Expression ◽  
Cytotoxic Activity ◽  
Cell Line ◽  
Cell Lines ◽  
Inhibitory Effect ◽  
Myeloma Cells ◽  
Ic50 Value ◽  
Induced Apoptosis ◽  
Resistant Cells

Abstract Multiple myeloma (MM) is a molecularly heterogeneous hematologic malignancy and remains mostly incurable despite the recent improvement of treatment strategies by several novel agents. Therefore, it is important to develop more efficacious drug against MM. YM155, a novel small molecule suppressant of survivin, shows anti-proliferative activities against various human cancer cells. YM155 was identified in a survivin gene promoter assay by high throughput screening of chemical libraries. In the present study, we investigated the cytotoxic mechanism of YM155 against human myeloma cells including bortezomib (BTZ) resistant cells (U266/BTZ). Three myeloma cell lines, U266, KMS-11 and KMS-12, were employed. YM155 inhibited the cell growth of these cell lines with the IC50 value of below 5 nM. YM155 suppressed the expression of mRNA and protein of survivin. We also found that YM155 inhibited the protein expression of Mcl-1, as an essential anti-apoptotic protein for survival of myeloma cells. In addition, we observed that YM155 markedly suppressed the phosphorylation of STAT3, which is known as transcription factor of Mcl-1. When KMS-12 cells were incubated with IL-6, phosphorylation of STAT3 and upregulation of Mcl-1 protein were observed. Treatment of KMS-12 with YM155 inhibited these events and eventually induced apoptosis in KMS-12 cells. Interestingly, inhibitory effect of YM155 on Mcl-1 protein expression was much stronger than that on survivin. RQ-PCR analysis indicated that the level of Mcl-1 mRNA was not affected after YM155 treatment. Immunoblot analysis showed that proteasome inhibitor MG-132 blocked the inhibition of Mcl-1 expression by YM155, suggesting that proteasome-mediated degradation is involved in YM155-induced Mcl-1 downregulation. MM is a low-growth-fraction disease and low proliferation of MM seems to contribute to resistance to various anticancer drugs. To determine whether YM155 shows cytotoxic effect against quiescent (G0/G1) MM cells, U266 were cultured in low-serum medium to enrich the G0/G1 population. Dual-parametric flow cytometric analysis using Hoechest33342 and the RNA specific dye pyronin Y revealed that YM155 potently induced cell death of quiescent (G0/G1) MM cells. In quiescent MM cells, inhibitory effect of YM155 on Mcl-1 protein expression was much stronger than that on survivin. We also examined whether similar effect of YM155 could be observed in primary MM cells. The majority of primary MM cells from patients was found to be in quiescent phase by cell-cycle analysis. YM155 showed similar cytotoxic activity against primary MM cells. In contrast, Ara-C, the S-phase specific anticancer drug, never killed quiescent primary MM cells. We established BTZ-resistant MM cell line (U266/BTZ). The IC50 value was 45-fold higher than its parental cell line. DNA sequencing data indicated that U266/BTZ cells possess a point mutation, G322A, in the gene encoding the proteasome beta-5 subunit. YM155 almost equally exhibited cytotoxic activity against U266/BTZ compared with parental cells. U266/BTZ displayed significantly lowered amounts of bcl-2, survivin and aurora-B kinase proteins. Interestingly, U266/BTZ overexpressed the Mcl-1 protein. Treatment with YM155 rapidly suppressed Mcl-1 protein expression and induced apoptosis. These data suggest that overexpression of Mcl-1 may contribute to bortezomib resistance and downregulation of Mcl-1 by YM155 could overcome it. In conclusion, our data indicate that YM155 may exert robust cytotoxic activity against quiescent (G0/G1) MM and bortezomib resistant cells via inhibition of Mcl-1 and survivin. Disclosures No relevant conflicts of interest to declare.

EZH2 Is Aberrantly Expressed and Plays a Pro-Proliferative Role Independent of Its Methyltransferase Activity in Natural Killer/T-Cell Lymphoma

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3498-3498
Author(s):  
Wee-Joo Chng ◽  
Junli Yan ◽  
Siok-Bian NG ◽  
Jim Tay ◽  
Baohong Lin ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Cell Lines ◽  
Nk Cell ◽  
Cell Lymphoma ◽  
Clinical Samples ◽  
Methyltransferase Activity ◽  
Natural Killer T Cell ◽  
Ezh2 Expression ◽  
Killer T Cell

Abstract Abstract 3498 Nasal-type Natural Killer/T-cell lymphoma (NKTL) is an aggressive lymphoid malignancy associated with very poor survival. A better understanding of the molecular abnormalities underlying this disease will lead to a better therapy. We recently performed whole genome gene expression studies and identify a number genes that are differentially expressed in NKTL as well as pathways which are activated in NKTL. EZH2, one of the genes identified in our study to be aberrantly over-expressed in NKTL, is a H3K27-specific histone methyltransferase and a component of the polycomb repressive complex 2 (PRC2), which plays a key role in the epigenetic maintenance of repressive chromatin mark. To the best of our knowledge, the mechanism of EZH2 overexpression in NKTL has not yet been described. In this study, we showed that EZH2 overexpression in NKTL can be attributed to a deregulated MYC-miRNA-EZH2 regulatory axis where MYC activation represses miRNAs that normally downregulate EZH2. He functionally demonstrated this relationship using NKTL cell lines while also demonstrating the correlation between MYC activation and EZH2 expression in clinical samples through the analysis of gene expression data as well as histological detection of nuclear MYC and EZH2 protein using a tissue microarray containing 35 NKTL clinical samples using immunohistochemistry. We then investigated the functional role of EZH2 in NKTL. We showed that ectopic overexpression of EZH2 in both primary NK cells and NK cell lines led to a significant growth advantage. Conversely, knock-down of EZH2 in NK cell lines resulted in growth inhibition of tumor cells. Intriguingly, ectopic EZH2 mutant deficient for histone methyltransferase activity was also able to confer growth advantage and rescue the growth inhibition upon endogenous EZH2 depletion in NKTL cells, indicating an oncogenic role of EZH2 independent of its gene silencing activity. Indeed, EZH2 expression in clinical NKTL samples is associated with higher Ki67 staining implying a role in driving NKTL proliferation. We further demonstrated that EZH2 directly binds to the gene promoter of Cyclin D1 and EZH2 promotes the transcription of Cyclin D1 independent of its enzymatic activity. Consistent with its potential oncogenic role, depletion of EZH2 using an inhibitor called DZNep also induced significant growth inhibition in NKTL cells. Taken together, our study demonstrates an unconventional role of EZH2 in promoting oncogenic growth in NKTL and provides novel insights into the oncogenic function of EZH2 in human cancers. The pro-proliferative properties of EZH2 in NKTL support the rationale for using of EZH2 inhibitors in the treatment of NKTL. However, it is important to note that in some tumor, EZH2 may be mediating its oncogenic functions through non-enzymatic mechanism. This has critical implications on the choice of specific inhibitors of its enzymatic function or compounds that can deplete EZH2 as the most appropriate therapeutic approach. Since targeting of EZH2 is an active area of drug development at present, there is great potential for the development of better treatment modalities and this is especially important for aggressive cancers, such as NKTL, for which no effective curative treatment is currently available. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Expression of Interleukin-9 in Nasal Natural Killer/T-Cell Lymphoma Cell Lines and Patients

2005 ◽  
Vol 11 (23) ◽  
pp. 8250-8257 ◽  
Author(s):  
Toshihiro Nagato ◽  
Hiroya Kobayashi ◽  
Kan Kishibe ◽  
Miki Takahara ◽  
Takeshi Ogino ◽  
...  
Keyword(s):  
T Cell ◽  
Natural Killer ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
T Cell Lymphoma ◽  
Lymphoma Cell ◽  
Natural Killer T Cell ◽  
Interleukin 9 ◽  
Killer T Cell ◽  
Natural Killer T

scholarly journals Oncogenic activation of STAT3 pathway drives PD-L1 expression in natural killer/T cell lymphoma.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. 7549-7549 ◽  
Author(s):  
Soon Thye Lim ◽  
Tammy Song ◽  
Jing Quan Lim ◽  
Yurike Laurensia ◽  
Jane Wan Lu Pang ◽  
...  
Keyword(s):  
T Cell ◽  
Natural Killer ◽  
Cell Lines ◽  
Somatic Mutations ◽  
Cell Lymphoma ◽  
T Cell Lymphoma ◽  
Natural Killer T Cell ◽  
Killer T Cell ◽  
Stat Pathway ◽  
Natural Killer T

7549 Background: Natural killer/T-cell lymphoma (NKTL) is a rare type of non-Hodgkin lymphoma that occurs more frequently in East Asia and Latin America and is associated with Epstein–Barr virus infection. Recent whole-exome sequencing studies in NKTL have reported recurrent somatic mutations in genes associated with JAK-STAT pathway, however the role of aberrant JAK-STAT signaling in tumor immune escape through PD-L1 regulation is unclear. Methods: To determine the prevalence of JAK-STAT pathway alteration in NKTL, we performed targeted sequencing of 188 genes associated with JAK-STAT pathway in 109 NKTL (22 Singapore cases, 79 China cases and 8 cell lines). Single nucleotide variants and micro-indels were called using Freebayes and candidate variants annotated using ANNOVAR. Ba/F3 model system was used to test the transformation capacity of identified variants. Cell lines were evaluated for PD-L1 expression by immunoblotting and flow cytometry. Tissue microarrays were examined for p-STAT3 and PD-L1 expression by immunohistochemistry. Results: We identified a total of 284 non-synonymous somatic mutations candidates in 114 genes, including 243 missense, 10 nonsense, 4 splice-site and 27 indel mutations. Recurrent mutations were most frequently located in STAT3 (25/109 cases, 23%) followed by TP53 (16/109 cases, 16%) and JAK3 (8/109 cases, 7%). A total of 18 STAT3 variants were identified including known hotspot mutations and novel mutations in the SH2, coiled coil and DNA-binding domains. Characterization of novel E616K mutant residing in the SH2 domain showed that E616K conferred IL3 independent growth to Ba/F3 cells, increased STAT3 phosphorylation and PD-L1 expression. Consistent with these findings, PD-L1 was over expressed in cell lines harboring STAT3 mutations. A positive correlation between PD-L1 and p-STAT3 expression was also observed in tumor tissue (R = 0.51, P = 0.02). Conclusions: We characterized a novel activating STAT3 mutant and demonstrated its ability to drive PD-L1 expression, which may promote tumor evasion from the antitumor immune response. The combination of PD-1/PD-L1 antibodies and STAT3 inhibitors might be a promising and novel therapeutic approach for NKTL in the future.

scholarly journals Expression of CD70 in nasal natural killer/T cell lymphoma cell lines and patients; its role for cell proliferation through binding to soluble CD27

2012 ◽  
Vol 160 (3) ◽  
pp. 331-342 ◽  
Author(s):  
Kazumi Yoshino ◽  
Kan Kishibe ◽  
Toshihiro Nagato ◽  
Seigo Ueda ◽  
Yuki Komabayashi ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cell ◽  
Natural Killer ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
T Cell Lymphoma ◽  
Lymphoma Cell ◽  
Natural Killer T Cell ◽  
Killer T Cell ◽  
Natural Killer T

scholarly journals Antitumor Activity of Dual BCL-2/BCL-Xl Inhibitor Pelcitoclax (APG-1252) in Natural Killer/T-Cell Lymphoma (NK/TCL)

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2062-2062
Author(s):  
Guangfeng Wang ◽  
Eric Liang ◽  
Ping Ming ◽  
Li Rui ◽  
Chunyang Tang ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Lines ◽  
Research Funding ◽  
Cell Lymphoma ◽  
T Cell Lymphoma ◽  
Publicly Traded ◽  
Antitumor Effects ◽  
Natural Killer T Cell ◽  
Tumor Tissues ◽  
Killer T Cell

Abstract Natural killer/T-cell lymphoma (NK/TCL) is one of the most common subtypes (10.4%) of peripheral T-cell lymphoma, which in turn accounts for 10% to 15% of all cases of non-Hodgkin lymphoma. NK/TCL occurs more frequently in Asia and Latin America than other regions, and although associated with Epstein-Barr virus (EBV) infection, NK/TCL has an unclear pathogenesis of genetic and molecular alterations. Asparaginase-based chemotherapy regimens are frequently used, typically with unsatisfactory outcomes. Novel targeted therapies, such as histone deacetylase (HDAC) inhibitors and programmed death-1 antibodies, are reported effective either as single agents or in combination with other agents. Studies have also shown that EBV-positive NK/TCL cell lines are B-cell lymphoma-extra large (BCL-xL) dependent. Other preclinical experiments have shown that BH3-mimetic drugs targeting BCL-xL-induced cell death in NK/TCL cell lines were effective in NK/TCL xenograft models. BCL-xL inhibitors have shown narrow therapeutic windows in clinical trials because of dose-limiting on-target thrombocytopenia. Pelcitoclax (APG-1252) is a novel dual BCL-2/BCL-xL inhibitor under clinical development for solid tumors. As a result of its unique prodrug design, APG-1252 can overcome the undesired platelet toxicity. This study evaluated the potential antitumor effect of APT-1252 in preclinical models of NK/TCL. Cell-based antiproliferation studies showed activity of APG-1252 and its more potent metabolite APG-1252-M1 toward NK/TCL cell lines that overexpressed BCL-xL. Half-maximal inhibitory concentrations (IC 50) for APG-1252 in SNK-1, SNK-6, and SNK-8 (EBV-positive NK/TCL) cell lines were 2.652 ± 2.606 µM, 1.568 ± 1.109 µM, and 0.557 ± 0.383 µM, respectively. Corresponding values for APG-1252-M1 were 0.133 ± 0.056 µM, 0.064 ± 0.014 µM, and 0.020 ± 0.008 µM, respectively. Mechanistic studies demonstrated that APG-1252 and APG-1252-M1 disrupted the complex of BCL-xL/BCL-2-associated X protein (Bax) and BCL-xL/BCL-2 homologous antagonist killer protein (Bak) in SNK-6 cells, thereby liberating these proapoptotic proteins and further activating downstream apoptosis pathways by cleaving poly-ADP ribose polymerase-1 (PARP-1) and caspase-3. In an SNK-6 xenograft model, administration of APG-1252 at 65 mg/kg and 100 mg/kg either twice or once weekly resulted in significant antitumor effects, with tumor growth rate (T/C%) values ranging from 13.7% to 30.7%. Furthermore, the combination of APG-1252 with HDAC inhibitor chidamide or DDGP (dexamethasone, cisplatin, gemcitabine, and pegaspargase) chemotherapy demonstrated synergistic effects. Pharmacokinetic assessment in mice showed that APG-1252 had a long half-life in plasma (127 hours) and tumor tissues (25.2 hours), justifying intermittent dosing schedules used in vivo. Importantly, the transformation of APG-1252 to APG-1252-M1 was 16 times higher in tumor tissues compared to plasma (22% vs. 1.3%) after administration of APG-1252, thereby suggesting that APG-1252 can reduce platelet toxicity caused by APG-1252-M1 in plasma. In conclusion, APG-1252 has promising antitumor effects in NK/TCL, either as a single agent or in combination with an HDAC inhibitor or chemotherapy. These findings provide evidence to further evaluate APG-1252 as a potential treatment for NK/TCL. Disclosures Wang: Ascentage Pharma Co., Ltd., Shanghai: Current Employment, Current equity holder in publicly-traded company. Liang: Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. Ming: Ascentage Pharma Co., Ltd., Shanghai: Current Employment, Current equity holder in publicly-traded company. Rui: Ascentage Pharma Co., Ltd., Taizhou: Current Employment, Current equity holder in publicly-traded company. Tang: Ascentage Pharma Co., Ltd., Taizhou: Current Employment, Current equity holder in publicly-traded company. LV: Ascentage Pharma Co., Ltd., Shanghai: Current Employment, Current equity holder in publicly-traded company. Ge: Ascentage Pharma Co., Ltd., Shanghai: Current Employment, Current equity holder in publicly-traded company. Zhang: Ascentage Pharma Co., Ltd., Taizhou: Current Employment, Current equity holder in publicly-traded company. Wang: Ascentage Pharma Co., Ltd., Taizhou: Current Employment, Current equity holder in publicly-traded company. Shang: Ascentage Pharma Co., Ltd., Shanghai: Current Employment, Current equity holder in publicly-traded company. Yang: Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding. Zhai: Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding; Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding.

Sign in / Sign up

Export Citation Format

Share Document