Bim Expression Research Articles

Sonrotoclax (BGB-11417) in Combination with Dexamethasone for the Treatment of Relapsed/Refractory Multiple Myeloma with t(11;14): Safety, Efficacy, and Determination of Recommended Phase 2 Dose

Background: B-cell lymphoma-2 (BCL2) family proteins represent attractive therapeutic targets as they play an important role in MM cell survival. In patients with relapsed/refractory (R/R) MM harboring t(11;14) for whom multiple prior lines of therapy failed, single-agent venetoclax, a first generation BCL2 inhibitor, demonstrated antimyeloma activity (Kumar S, et al. Blood. 2017). Dexamethasone, a long-standing mainstay of treatment for MM, increases the expression of both BCL2 and Bim. This results in a greater dependency on BCL2 for tumor survival, ultimately increasing the sensitivity to a BCL2 inhibitor. Sonrotoclax (BGB-11417) is a BH3 mimetic that binds and inhibits BCL2 with potency >10x that of venetoclax in biochemical assays. BGB-11417-105 (NCT04973605) is an ongoing phase 1b/2 trial designed to evaluate safety and efficacy of sonrotoclax as monotherapy, in combination with dexamethasone, or in combination with dexamethasone plus carfilzomib in patients with R/R MM harboring the t(11;14). Here, we report preliminary data from the sonrotoclax plus dexamethasone dose-escalation (DE) cohorts. Methods: Eligible patients have R/R MM that is t(11;14) positive by fluorescence in situ hybridization (per central assessment) who have received 1-7 prior lines of therapy for MM with previous exposure to a proteasome inhibitor and an IMiD agent. In dose escalation, patients received 80, 160, 320, or 640 mg of sonrotoclax daily with 40 mg of dexamethasone weekly until intolerability, disease progression, or death. The primary objectives in the DE cohorts were to assess the overall safety/tolerability profile as well as determine the maximum tolerated dose (MTD)/maximum assessed dose (MAD) and establish the recommended phase 2 dose (RP2D). AEs were reported per CTCAEs v5.0; safety was assessed by a safety monitoring committee (SMC) after a 21-day dose-limiting toxicity (DLT) window for each cohort and was guided by a modified toxicity probability interval method (mTPI-2). Disease responses were assessed per International Myeloma Working Group 2016 criteria. Results: As of May 26, 2023, 19 patients have been enrolled in the 80-, 160-, and 320-mg (n=3 each) and 640-mg (n=10 patients) dose-escalation cohorts. The median age was 68 years (range, 52-81 years). The median prior lines of therapy was 4 (range, 1-12) and 11 patients (58%) failed on a prior anti-CD38 antibody. The most common AEs (>20% of all patients) were insomnia (n=9; 47%), fatigue (n=6; 32%), nausea (n=5; 26%), and arthralgia (n=4; 21%); none of which were severity grade ≥3. Three patients (16%) experienced grade ≥3 treatment-emergent AEs (TEAEs). One patient (33%) in the 160-mg cohort had grade 3 increases in liver enzymes and diarrhea; one patient (10%) in the 640-mg cohort had a grade 3 decrease lymphocyte count and hypokalemia; and one patient (10%) in the 640-mg cohort had grade 3 cataracts and retinal detachment. Three patients experienced COVID-19 (grade 1-2, n=2; grade ≥3, n=1). Three patients experienced TEAEs that led to treatment discontinuation (COVID-19, cancer pain, hematuria; n=1 each). No patient, across all dose levels tested, experienced a DLTs; thus, sonrotoclax 640 mg daily was the determined to be the MAD and the RP2D in combination with dexamethasone. Four patients (21%) died while on study; however, no deaths were determined by the investigators to be associated with study treatment. One patient died from COVID-19 while receiving study therapy; three additional patients died ≥50 days after treatment discontinuation (COVID, progressive disease, and unknown causes, n=1 each). With a median treatment duration of 120 days (range, 30-526), ORR was 58%; 11 patients had a PR or better (n=6, PR; n=2, very good PR; n=2, CR; n=1, stringent CR [sCR]; Figure). The ORR for the 640-mg cohort was 70% (n=3, PR; n=2 VGPR; n=1, CR; n=1, sCR). Nine patients remained on treatment; the longest duration of response was 483 days (20 cycles) which, at data cutoff, was still ongoing. Conclusion: Sonrotoclax plus dexamethasone was generally well tolerated in patients with R/R MM harboring t(11;14) at doses up to 640 mg, and initial safety and efficacy results are promising. The SMC has recommended 640 mg in combination with dexamethasone as the RP2D. Recruitment is ongoing for the sonrotoclax in combination with dexamethasone and carfilzomib dose-finding arms and the sonrotoclax plus dexamethasone indication expansion cohort.

ERK1/2 Inhibition Overcomes Resistance to Venetoclax in AML By Inhibiting Drp1 Dependent Mitochondrial Fission

Background: Primary or secondary resistance to venetoclax is frequently associated with mutational/non-mutational activation of MAPK pathways. ERK1/2 are terminal kinases in MAPK pathway and may be an appropriate target regardless of the upstream mechanisms that activate the pathway. ERK1/2 mediated phosphorylation of Drp1 promotes mitochondrial fission and MAPK-driven tumor growth in RAS driven solid cancers (Kashatus et al., Mol Cell. 2015). However, the role of Drp1 dependent mitochondrial dynamics in therapeutic resistance in AML is unexplored. Methods: ERK1/2 was inhibited using Compound 27 (ERKi, Heightman et al., J Med Chem. 2018), an analog of ASTX029 (Munck et al., Mol Cancer Ther. 2021) in vitro and using ASTX029 in vivo. Preclinical models of venetoclax resistance and primary patient samples (n=8) were used to assess the synergy of concomitant Bcl2 and ERK1/2 inhibition (ERKi). In addition, a comprehensive analysis of alteration of signaling pathways, apoptotic signatures and DNA damage responses in response to ERKi+/-venetoclax were analyzed by mass cytometry based proteomic analysis (CyTOF) and immunoblotting. The potential clinical relevance of ERK1/2 inhibition to overcome venetoclax resistance was confirmed in a PDX model of AML (established from an AML patient who relapsed after venetoclax/decitabine treatment). Mitochondrial images were acquired using super-resolution imaging with OMX-Blaze followed by quantification with Imaris. Results : We previously reported the synergy of ERK1/2 inhibition using Compound 27 with venetoclax at inducing apoptosis in RAS mutated and/or venetoclax resistant AML cells including venetoclax resistant isogenic lines (Sharma et al., Blood 140; Supplement 1, 2022). Venetoclax+ERKi depleted leukemia progenitor cells in primary AML samples (CI:0.03-0.23) and impaired clonogenic growth of NRAS mutant PDX cells. In a PDX mouse model of post venetoclax/decitabine-relapsed AML, ASTX029+venetoclax treatment improved survival compared to vehicle (median survival 76.5 days vs. 50 days, p=0.0006) and venetoclax alone (median survival 76.5 days vs. 51.5 days, p=0.0065) (Figure 1) with corresponding reduction in leukemia burden in bone marrow (p<0.0001) and spleen (p<0.0001). CyTOF analysis using PDX bone marrow showed decreased expression of Mcl-1 and pMcl-1-T163 and an increased expression of BIM in response to ERKi+/-venetoclax (Figure 1). To maintain stemness in AML, mitochondrial ROS mitigation and Drp1-mediated mitochondrial fission are crucial (Schimmer et al., Cell Stem Cell. 2018). The inhibition of ERK1/2 resulted in decreased pDrp1-Ser616, along with an increase in mitochondrial length (p<0.001) suggesting impaired mitochondrial fission. This was accompanied by a decrease in mitochondrial membrane potential (p<0.0001) and an increase in mitochondrial ROS (p<0.0001). Overexpression (OE) of a phospho-mimetic i.e. Drp1-Ser616Glu-Ser637Ala led to shorter mitochondrial length (Figure 2), suggesting enhanced fission, a distinct metabolic phenotype with decreased ROS production and decreased mitochondrial depolarization with venetoclax+/- ERKi. Finally, Drp1 phospho-mimetic OE reversed apoptosis induction by venetoclax +/- ERKi (Figure 2) as compared to the wild-type and phospho-null (Ser616Ala) Drp1 (p<0.001) expressing cells, supporting the role of mitochondrial fission in resistance to venetoclax. Conclusion: The increased mitochondrial fission driven by ERK1/2 mediated phosphorylation of Drp1 contributes to venetoclax resistance in AML and inhibiting ERK1/2/Drp1 axis overcomes resistance to venetoclax by inhibiting mitochondrial fission (Figure 2). These data provide a strong rationale for the combination of ERK1/2 and Bcl-2 inhibitors in the treatment of AML.

The novel small molecule BH3 mimetic nobiletin synergizes with vorinostat to induce apoptosis and autophagy in small cell lung cancer

Small cell lung cancer (SCLC) is a highly lethal subtype of lung cancer with few therapeutic options; therefore, the identification of new targets and drugs with potent combination therapy is desirable. We previously screened BH3 mimetics from a natural product library, and in this study, we validated nobiletin as a BH3 mimetic. Specifically, we observed its combination potential and mechanism with vorinostat in SCLC in vitro and in vivo. The results showed that combination treatment with nobiletin and vorinostat reduced the proliferation of SCLC H82 cells and increased the levels of apoptotic proteins such as cleaved caspase-9 and cleaved PARP. The combination treatment increased LC3-II expression and induced autophagic cell death. In addition, this treatment significantly inhibited H82 cell xenograft SCLC tumor growth in nude mice. The combination treatment with nobiletin and vorinostat efficiently increased autophagy by inhibiting the PI3K-AKT-mTOR pathway and promoting dissociation of the BCL-2 and Beclin 1 complex, increasing the level of isolated Beclin 1 to stimulate autophagy. Molecular docking and surface plasmon resonance analysis showed that nobiletin stably bound to the BCL-2, BCL-XL and MCL-1 proteins with high affinity in a concentration-dependent manner. These results suggest that nobiletin is a BH3-only protein mimetic. Furthermore, the combination of nobiletin with vorinostat increased histone H3K9 and H3K27 acetylation levels in SCLC mouse tumor tissue and enhanced the expression of the BH3-only proteins BIM and BID. We conclude that nobiletin is a novel natural BH3 mimetic that can cooperate with vorinostat to induce apoptosis and autophagy in SCLC.

Oridonin Synergistically Enhances the Pro-Apoptotic Effect of Venetoclax on Acute Myeloid Leukemia Cells by Inhibiting AKT Signaling.

Acute myeloid leukemia (AML) is a recurrence-prone hematologic malignancy. The advent of molecularly targeted therapies provides new opportunities to enhance the effectiveness of AML treatments. Venetoclax, a selective inhibitor of the anti-apoptotic protein Bcl-2, has shown promising results; however, resistance often arises due to elevated expression of the Mcl-1 protein, among other factors. Overcoming this resistance to improve therapeutic outcomes is a pressing issue that requires further investigation. Studies have demonstrated that oridonin, by inhibiting AKT signaling that regulates Mcl-1 expression, can effectively suppress tumor cell growth. This study aims to investigate whether oridonin can synergistically enhance the anti-leukemic effects of venetoclax and explore the underlying mechanisms behind this effect. In vitro experiments were performed to evaluate the effects of the combination of oridonin and venetoclax on AML cell proliferation, apoptosis, cell cycle distribution, and mitochondrial membrane potential. Transcriptome sequencing was used to elucidate the molecular mechanisms underlying the synergistic induction of AML cell apoptosis by the combination therapy. Western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR) techniques were used to validate the findings. Additionally, an AML mouse model was established to observe the synergistic anti-AML effects of venetoclax combined with oridonin in vivo. Both venetoclax and oridonin individually exhibited inhibitory effects on AML cell proliferation, resulted in cell cycle arrest, and induced cell apoptosis. Moreover, combination of the two drugs resulted in a synergistic effect. We also observed that oridonin inhibited AKT phosphorylation, upregulated the expression of Bim and Bax proteins, facilitated Mcl-1 degradation, and enhanced the apoptotic effects of venetoclax in AML cells. Finally, in vivo experiments demonstrated that the combination of oridonin and venetoclax effectively inhibited the growth of AML xenograft tumors in mice and prolonged the survival time of tumor-bearing mice. Oridonin and venetoclax synergistically promote AML cell apoptosis by inhibiting AKT signaling.

Glioma Stem Cells Are Sensitized to BCL-2 Family Inhibition by Compromising Histone Deacetylases.

Glioblastoma (GBM) remains an incurable disease with an extremely high five-year recurrence rate. We studied apoptosis in glioma stem cells (GSCs) in response to HDAC inhibition (HDACi) combined with MEK1/2 inhibition (MEKi) or BCL-2 family inhibitors. MEKi effectively combined with HDACi to suppress growth, induce cell cycle defects, and apoptosis, as well as to rescue the expression of the pro-apoptotic BH3-only proteins BIM and BMF. A RNAseq analysis of GSCs revealed that HDACi repressed the pro-survival BCL-2 family genes MCL1 and BCL-XL. We therefore replaced MEKi with BCL-2 family inhibitors and observed enhanced apoptosis. Conversely, a ligand for the cancer stem cell receptor CD44 led to reductions in BMF, BIM, and apoptosis. Our data strongly support further testing of HDACi in combination with MEKi or BCL-2 family inhibitors in glioma.

Anticancer Effects in HT-29 Cells and Anti-Inflammatory Effects on Mouse Splenocytes of Broccoli Cultivated with Deep Sea Water Minerals in Organic Farming

In this study, broccoli grown with deep sea water minerals (DSWMs) confirmed anticancer effects in HT-29 colorectal cancer cells and anti-inflammatory effects in C57BL/6 mouse splenocytes. Natural dream cultured broccoli (NB) grown with DSWMs had elevated sodium (Na) and calcium (Ca) levels and enhanced the expression of p53 and p21, both of which are associated with cell cycle arrest in HT-29 colorectal cancer cells. It also decreased the expression of Bax, Bad, Bim, Bak, caspase-9, and caspase-3. In lipopolysaccharide (LPS)-treated C57BL/6 mouse splenocytes, NB produced little nitric oxide (NO). ELISA research indicated that NB decreased IL-1β, IL-6, TNF-α, IFN-γ, and IL-12 expression while increasing NK cell activity. As a result, broccoli cultivated with deep water minerals has better anticancer and anti-inflammatory properties than conventional and organic farming.

Targeting Oncogenic Mutant p53 and BCL-2 for Small Cell Lung Cancer Treatment.

Through a unique genomics and drug screening platform with ~800 solid tumor cell lines, we have found a subset of SCLC cell lines are hypersensitive to venetoclax, an FDA-approved inhibitor of BCL-2. SCLC-A (ASCL1 positive) and SCLC-P (POU2F3 positive), which make up almost 80% of SCLC, frequently express high levels of BCL-2. We found that a subset of SCLC-A and SCLC-P showed high BCL-2 expression but were venetoclax-resistant. In addition, most of these SCLC cell lines have TP53 missense mutations, which make a single amino acid change. These mutants not only lose wild-type (WT) p53 tumor suppressor functions, but also acquire novel cancer-promoting activities (oncogenic, gain-of-function). A recent study with oncogenic mutant (Onc)-p53 knock-in mouse models of SCLC suggests gain-of-function activity can attenuate chemotherapeutic efficacy. Based on these observations, we hypothesize that Onc-p53 confers venetoclax resistance and that simultaneous inhibition of BCL-2 and Onc-p53 induces synergistic anticancer activity in a subset of SCLC-A and SCLC-P. We show here that (1) down-regulation of Onc-p53 increases the expression of a BH3-only pro-apoptotic BIM and sensitizes to venetoclax in SCLC-P cells; (2) targeting Onc-p53 by the HSP90 inhibitor, ganetespib, increases BIM expression and sensitizes to venetoclax in SCLC-P and SCLC-A cells. Although there are currently many combination studies for venetoclax proposed, the concept of simultaneous targeting of BCL-2 and Onc-p53 by the combination of venetoclax and HSP90 inhibitors would be a promising approach for SCLC treatment.

Epinodosin suppresses the proliferation, invasion, and migration of esophageal squamous cell carcinoma by mediating miRNA-143-3p/Bcl-2 axis.

Epinodosin has shown antibacterial and antitumor biological characteristics in the documents. We found that Epinodosin has an effective inhibitory effect on esophageal squamous cell carcinoma (ESCC). However, the potential roles and mechanisms of Epinodosin in ESCC remain unclear. We performed many experiments to clarify the effect and mechanism of Epinodosin on ESCC. In this study, cell viability, invasion, migration, and apoptosis were determined by 3-(4,5-dimethyl-2-thiazolyl)-2,-diphenytetrazoliumromide (MTT), Transwell, and flow cytometry. The differentially expressed miRNAs were screened through RNA transcriptome sequencing. The expression levels of miRNA-143-3p and some proteins were measured by real-time polymerase chain reaction (PCR) and Western blot. The anticancer effects of Epinodosin in vivo were determined by a nude mouse model. Epinodosin suppressed cell proliferation/invasion/migration and induced ESCC cell apoptosis. Epinodosin remarkably affected the protein expression of mitogen-activated protein kinase (MAPK) signaling pathway. The animal experiments demonstrated that Epinodosin could attenuate the growth of ESCC tumors in nude mice. The expression of p53, Bim, and Bax was upregulated, while that of Bcl-2 was downregulated in tumor tissues. In conclusion, Epinodosin suppresses cell viability/invasion/migration, while induces ESCC cell apoptosis by mediating miRNA-143-3p and Bcl-2, and can markedly attenuate the growth of ESCC tumors in nude mice.

PE_PGRS45 (Rv2615c) protein of Mycobacterium tuberculosis perturbs mitochondria of macrophages.

The PE_PGRS proteins have coevolved with the antigenic ESX-V secretory system and are abundant in pathogenic Mycobacterium. Only a few PE_PGRS proteins have been characterized, and research suggests their role in organelle targeting, cell death pathways, calcium (Ca2+ ) homeostasis and disease pathogenesis. ThePE_PGRS45 (Rv2615c) protein was predicted to contain mitochondria targeting sequences by in silico evaluation. Therefore, we investigated the targeting of the Rv2615c protein to host mitochondria and its effect on mitochondrial functions. In vitro experiments showed the Rv2615c protein colocalized with the mitochondria and led to morphological mitochondrial perturbations. Recombinant Rv2615c was observed to cause increased levels of intracellular reactive oxygen species and the adenosine diphosphate-to-adenosine triphosphate ratio. The Rv2615c protein also induced mitochondrial membrane depolarization and the generation of mitochondrial superoxide. We observed the release of cytochrome C into the cytoplasm and increased expression of proapoptotic genes Bax and Bim with no significant change in anti-apoptotic Bcl2 in Rv2615c-stimulated THP1 macrophages. Ca2+ is a key signaling molecule in tuberculosis pathogenesis, modulating host cellresponses. As reported for other PE_PGRS proteins, Rv2615c also has Ca2+ -binding motifs and thus can modulate calcium homeostasis in the host. We also observed a high level of Ca2+ influx in THP1 macrophages stimulated with Rv2615c. Based on these findings, we suggest that Rv2615c may be an effector protein that could contribute to disease pathogenesis by targeting host mitochondria.

Efficacy of retreatment with polatuzumab vedotin in combination with rituximab in polatuzumab vedotin-resistant DLBCL models

Polatuzumab vedotin (Pola) was approved for first-line and relapsed/refractory (r/r) diffuse large B-cell lymphoma (DLBCL) in many countries. This means that retreatment with Pola for r/r DLBCL could be considered after first-line Pola treatment; however, there is currently no evidence on the effectiveness of Pola-retreatment. To address this, we established two Pola-resistant cells from DLBCL cells (SU-DHL-4 and STR-428) and evaluated the combination efficacy of Pola plus rituximab (Rit), the key component of DLBCL therapy. MDR1 overexpression and decreased Bim expression were suggested to be the resistant mechanisms to Pola in Pola-resistant SU-DHL-4 and Pola-resistant STR-428, respectively. In these cells, Pola significantly increased Rit-induced CDC sensitivity either with increased MAC formation or reduced Mcl-1 expression. Additionally, treatment with Pola + Rit significantly enhanced antitumor activity in Pola-resistant STR-428 xenograft mouse models. Based on these results, Pola + Rit retreatment could have preserved efficacy because of the effect of Pola on sensitizing cells to Rit.

Triggering of Endoplasmic Reticulum Stress by Tannic Acid Inhibits the Proliferation and Migration of Colorectal Cancer Cells.

Due to the pivotal role of endoplasmic reticulum (ER) stress in cancers, interfering with its function can cause the accumulation of unfolded proteins, which ultimately leads to the activation of the unfolded protein response (UPR) signaling pathway and apoptosis. Therefore, the use of plant compounds such as tannic acid with UPR-inducing properties can be proposed as a possible treatment method for cancer. In this study, we investigated the effect of tannic acid on cell migration, colony formation, growth, and UPR-induced apoptosis in the SW48 colorectal cancer cell line. The MTT assay was performed to investigate the cytotoxic effect of tannic acid. We performed the qPCR method to elucidate the effect of tannic acid on the expression of Bim, MMP-9, Bcl-xL, cyclin D1, CHOP, and ATF4 genes. We also used the colony formation and migration experiments to investigate the effect of this compound on the colony formation and migration ability of tumor cells. Finally, we used Hoechst staining to measure cell apoptosis. Tannic acid inhibited the cell survival, clonogenic, and migration of colon cancer cells. This compound increased the expression of ER stress-mediated UPR genes, ATF4 and CHOP. Moreover; tannic acid increased the expression of pro-apoptotic proteins like Bim, while at the same time causing a sharp decline in the expression of anti-apoptotic protein Bcl-xL. A decline in MMP-9 expression confirmed the anti-metastatic role of this compound. Taken together, tannic acid can induce apoptosis via ER stress-mediated UPR pathway, and has a suppressive effect on cell viability, growth, migration, colony formation, and metastasis, suggesting it may be a potential drug in colorectal cancer treatment.

Integrating Network Pharmacology and Experimental Validation to Explore the Effects and Mechanisms of Qinghao Biejia Decoction and Its Active Compound Artemisinin B Against Non-Small-Cell Lung Cancer.

To explore the pharmacological effects and mechanisms of Qinghao Biejia decoction (QBD) against non-small-cell lung cancer (NSCLC) based on network pharmacology and to verify the anticancer effect of artemisinin B (ART B), the active ingredient of QBD, on H1299 cells. Ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) was applied to explore the chemoprofile of QBD. A zebrafish xenograft model was used to determine the anti-cancer efficacy of QBD. Cell counting kit-8 assay, terminal deoxyribonucleotide transferase-mediated-dUTP nick-end labeling assay; immunofluorescence, and flow cytometry were used to evaluate the in vitro anti-proliferative and pro-apoptotic effects of QBD and ART B on H1299 cells. Subsequently, the related targets and action mechanisms of both QBD and ART B predicted by network pharmacological analyses were experimentally validated by real-time PCR and Western blot assays on H1299 cells. UPLC-QTOF-MS/MS identified a total of 69 compounds (such as ART B, mangiferin, and artemisinic acid) in QBD. The in vivo data showed that QBD significantly inhibited the growth of H1299 cells in xenograft larval zebrafish from 125 to 500 μg/mL. The in vitro data showed that QBD induced apoptosis of H1299 cells, accompanied by down-regulating the expression of BCL-2 and up-regulating the expression of BIM, PUMA, BAX, c-PARP, γ-H2A.X, c-CASP3, and c-CASP8. Alike QBD, ART B exerted similar anti-proliferative and pro-apoptotic effects on H1299 cells. Moreover, ART B inhibited expressions of BCL2L1, AKT1, AKT2, MMP-2, and EGFR, and up-regulated ALB expression. Mechanistically, ART B promoted apoptosis of H1299 cells by inhibiting PI3K/Akt signaling pathway. This study revealed the anti-NSCLC efficacy of QBD. ART B, the effective component of QBD, plays an anti-NSCLC role by down-regulating the PI3K-Akt signaling pathway. It suggests that QBD and ART B are promising drug candidates for NSCLC treatment.

Glutaredoxin-1 promotes lymphangioleiomyomatosis progression through inhibiting Bim-mediated apoptosis via COX2/PGE2/ERK pathway.

Lymphangioleiomyomatosis (LAM) is a female-predominant interstitial lung disease, characterized by progressive cyst formation and respiratory failure. Clinical treatment with the mTORC1 inhibitor rapamycin could relieve partially the respiratory symptoms, but not curative. It is urgent to illustrate the fundamental mechanisms of TSC2 deficiency to the development of LAM, especially mTORC1-independent mechanisms. Glutaredoxin-1 (Glrx), an essential glutathione (GSH)-dependent thiol-oxidoreductase, maintains redox homeostasis and participates in various processes via controlling protein GSH adducts. Redox signalling through protein GSH adducts in LAM remains largely elusive. Here, we demonstrate the underlying mechanism of Glrx in the pathogenesis of LAM. 1. Abnormal Glrx expression in various kinds of human malignancies was identified by the GEPIA tumour database, and the expression of Glrx in LAM-derived cells was detected by real-time quantitative reverse transcription (RT-qPCR) and immunoblot. 2. Stable Glrx knockdown cell line was established to evaluate cellular impact. 3. Cell viability was determined by CCK8 assay. 4. Apoptotic cell number and intracellular reactive oxygen species (ROS) level were quantified by flow cytometry. 5. Cox2 expression and PGE2 production were detected to clarify the mechanism of Bim expression modulated by Glrx. 6. S-glutathionylated p65 was enriched and detected by immunoprecipitation and the direct regulation of Glrx on p65 was determined. 7. The xenograft animal model was established and photon flux was analyzed using IVIS Spectrum. In LAM, TSC2 negatively regulated abnormal Glrx expression and activation in a mTORC1-independent manner. Knockdown of Glrx increased the expression of Bim and the accumulation of ROS, together with elevated S-glutathionylated proteins, contributing to the induction of apoptotic cell death and inhibited cell proliferation. Knockdown of Glrx in TSC2-deficient LAM cells increased GSH adducts on nuclear factor-kappa B p65, which contributed to a decrease in the expression of Cox2 and the biosynthesis of PGE2. Inhibition of PGE2 metabolism attenuated phosphorylation of ERK, which led to the accumulation of Bim, due to the imbalance of its phosphorylation and proteasome degradation. In xenograft tumour models, knockdown of Glrx in TSC2-deficient LAM cells inhibited tumour growth and increased tumour cell apoptosis. Collectively, we provide a novel redox-dependent mechanism in the pathogenesis of LAM and propose that Glrx may be a beneficial strategy for the treatment of LAM or other TSC-related diseases.

Aged black garlic extract inhibits the growth of estrogen receptor-positive breast cancer cells by downregulating MCL-1 expression through the ROS-JNK pathway.

The black garlic is produced from the raw garlic by Milliard reaction at high temperature (~60-90°C) and humidity (~70-90%). In this process, the pungent odor and gastrointestinal irritation effects of the raw garlic are reduced. At the same time, unstable compounds such as allicin are converted into stable organosulfur compounds with antioxidant activity. Previous studies have confirmed that black garlic extract has anti-tumor effects and could inhibit the proliferation of various tumor cells, including breast cancer cells MCF-7. However, the mechanisms of the anti-tumor effects remain unclear. In this study, we found that the black garlic extract could inhibit the proliferation, invasion, and metastasis of estrogen receptor-positive breast cancer cells, promote their apoptosis, and inhibit their epithelial-mesenchymal transition. Mechanistically, the black garlic extract reduced the expression of the anti-apoptotic protein MCL-1, which was achieved by modulating the ROS-JNK signaling pathway. In addition, the black garlic extract also decreased the expression of BCL-2 and increased the expression of BAX and BIM. We also found that the black garlic extract, in combination with venetoclax, a BCL-2 inhibitor, synergistically kills the estrogen receptor-positive breast cancer cells. These results suggested that black garlic extract has great therapeutic value and prospects for estrogen receptor-positive breast cancer treatment.

Combination Therapy With MDM2 and MEK Inhibitors Is Effective in Patient-Derived Models of Lung Adenocarcinoma With Concurrent Oncogenic Drivers and MDM2 Amplification

IntroductionAlthough targeted therapies have revolutionized the therapeutic landscape of lung adenocarcinomas (LUADs), disease progression on single-agent targeted therapy against known oncogenic drivers is common, and therapeutic options after disease progression are limited. In patients with MDM2 amplification (MDM2amp) and a concurrent oncogenic driver alteration, we hypothesized that targeting of the tumor-suppressor pathway (by means of restoration of p53 using MDM2 inhibition) and simultaneous targeting of co-occurring MAPK oncogenic pathway might represent a more durably effective therapeutic strategy. MethodsWe evaluated genomic next-generation sequencing data using the Memorial Sloan Kettering Cancer Center-Integrated Mutation Profiling of Actionable Cancer Targets platform to nominate potential targets for combination therapy in LUAD. We investigated the small molecule MDM2 inhibitor milademetan in cell lines and patient-derived xenografts of LUAD with a known driver alteration and MDM2amp. ResultsOf 10,587 patient samples from 7121 patients with LUAD profiled by next-generation sequencing, 6% (410 of 7121) harbored MDM2amp. MDM2amp was significantly enriched among tumors with driver alterations in METex14 (36%, p < 0.001), EGFR (8%, p < 0.001), RET (12%, p < 0.01), and ALK (10%, p < 0.01). The combination of milademetan and the MEK inhibitor trametinib was synergistic in growth inhibition of ECLC5-GLx (TRIM33-RET/MDM2amp), LUAD12c (METex14/KRASG12S/MDM2amp), SW1573 (KRASG12C, TP53 wild type), and A549 (KRASG12S) cells and in increasing expression of proapoptotic proteins PUMA and BIM. Treatment of ECLC5-GLx and LUAD12c with single-agent milademetan increased ERK phosphorylation, consistent with previous data on ERK activation with MDM2 inhibition. This ERK activation was effectively suppressed by concomitant administration of trametinib. In contrast, ERK phosphorylation induced by milademetan was not suppressed by concurrent RET inhibition using selpercatinib (in ECLC5-GLx) or MET inhibition using capmatinib (in LUAD12c). In vivo, combination milademetan and trametinib was more effective than either agent alone in ECLC5-GLx, LX-285 (EGFRex19del/MDM2amp), L13BS1 (METex14/MDM2amp), and A549 (KRASG12S, TP53 wild type). ConclusionsCombined MDM2/MEK inhibition was found to have efficacy across multiple patient-derived LUAD models harboring MDM2amp and concurrent oncogenic drivers. This combination, potentially applicable to LUADs with a wide variety of oncogenic driver mutations and kinase fusions activating the MAPK pathway, has evident clinical implications and will be investigated as part of a planned phase 1/2 clinical trial.

20P Spatial analysis of residual tumor tissue provides new clues for post-neoadjuvant treatment approaches in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a very heterogeneous disease with high metastatic recurrence risk. We showed (PMID 34535679) that TNBCs relapsing rapidly (RR) after NACT (in ≤ 12 months) are highly proliferative, immune-cold, often with large residual cancer burden (RCB) and fatal outcome. No specific biomarkers or therapeutic targets are known for this clinical category. In this study we performed spatial molecular analysis of the RR and the RCB3 TNBCs, with the aim to help improving treatment of the TNBC patients with the poorest prognosis. We analyzed residual tumor tissue samples of TNBC patients treated by standard NACT from 01/01/2009 to 31/12/2021. The cases were classified into RR, standardly-relapsing (SR, 1-5 years post-NACT) and without recurrences (NR). The amount of tumor-infiltrating lymphocytes (TILs) was determined by optical microscopy (H&E). Tissue protein expression was spatially resolved by GeoMx® Digital Spatial Profiler (NanoString Technology). Sixteen, 17 and 47 RR, SR and NR cases were analyzed, respectively. GeoMx analysis included 216 Region-of-Interest (ROIs) of tumor microenvironment (TME) and 207 of tumor cells (TC), with balanced (∼50/50) numbers of peripheral (P) and central (C) ROIs. Tumors and ROIs were classified into TIL-rich (LR) and TIL-poor (LP) using cut-off of 10% TILs. The RR TNBCs showed higher Ki67, cleaved caspase 9, granzyme B (GZMB), FoxP3 and fibronectin (FBNCT) in TME-P-LR ROIs but higher GADPH, TIM-3, PD-L1 and IDO in TME-P-LP ROIs. Compared to TNBC-SR, the RR had higher GZMB and CD34 in TME-P-LR ROIs. In TME-C-LR ROIs of the RRs, CD8 expression was low, as well as the one of CD45, CD3 and CD8 in TME-C-LP. The RCB3 category contained 9, 8 and 10 RR, SR and NR cases, respectively. Although most RCB3 cases were TIL-poor, the NR cases showed significantly higher expression of CD3, CD8, GZMA, CD4, CD56, CD95, LAG3, HLA-DR, BIM and BCL6 than the RR cases. By this study we revealed several potential therapeutic targets (fibronectin, IDO, TIM-3, CD34 /angiogenesis) in the RR TNBCs. Interestingly, we also showed that some RCB3 cases have immune-activated TME and good prognosis. Spatial tissue analysis was crucial for these discoveries.

Abstract A08: Targeting HSP90 epichaperome in TP53 mutant AML

Abstract The Bcl-2 inhibitor venetoclax (VEN)/hypomethylation agent (HMA) combination achieves high response rates, has improved outcomes for many patients with AML and is now considered standard of care for patients who are older or unfit to receive intensive chemotherapy. However, the median overall survival is only 14.7 months on this regimen and only 2.5 months post relapse. Molecular analysis demonstrates that mutations in TP53 and oncogenic kinases are key determinants of lower response rates and early relapse. Preclinical studies also show that increased kinase signaling in AML stem/progenitor cells in TP53 mutant AML. The heat shock protein 90 (HSP90) chaperone, a key regulator of proteostasis, is responsible for the correct folding of kinases and transcription factors. HSP90-associated-epichaperomes, formed in malignant cells, are complexes consisting of HSP90, co-chaperones, and associated proteins that support the maturation, activity, and stability of many cancer-associated kinases and transcription factors including mutated TP53. Hence, HSP90 epichaperome inhibition has the potential of targeting TP53 mutant AML. In contrast to other HSP90 ATP inhibitors, PU-H71 (zelavespib) is a competitive inhibitor specific for the ATP binding site of HSP90 epichaperomes. We here investigate the therapeutic potentials of targeting HSP90 epitherachorme with PU-H71 in TP53 mutated AML. Western blot analysis found increased HSP90 and several signaling proteins in TP53 knockout and mutant Molm13 cells generated by CRISPR/cas-9 or by exposing to idasanutlin, compared to the isogeneic wild-type controls. Using a fluorochrome-labelled PU-H71 and flow cytometry, we demonstrate the presence of HSP90 epichaperomes in AML cells and AML stem/progenitor cells with TP53 mutations, but not in normal bone marrow and bone marrow stem/progenitor cells. PU-H71 effectively kills AML cells and AML stem/progenitor cells with various TP53 mutations, and prolongs survival in TP53-mutant AML xenograft mice with minimal effects on normal CD34+ bone marrow cells and hematopoiesis. PU-H71 increased Bim expression and enhanced VEN activity in AML cells and AML stem/progenitor cells with TP53 mutations. Importantly, in a mixture of TP53 wild-type/R248W Molm13 cells (1000:1), nutlin3a selectively killed TP53 wild-type but enriched TP53 mutant Molm13 cells; VEN treatment favored the outgrowth of TP53-mutant cells, while PU-H71 effectively killed TP53 wild-type and mutant cells. Furthermore, PU-H71 exhibited anti-leukemia activity against both TP53 WT and mutant AML cells, which was further enhanced by VEN in vivo in a xenograft model of mixed TP53 WT and mutated Molm13 cells (10:1). Our data support that the HSP90 epichaperome is essential for the growth and survival of AML and AML stem/progenitor cells harboring mutant TP53. Inhibition of HSP90 by PU-H71 targets AML cells/stem/progenitor cells enhances VEN activity and prevents outgrowth of VEN-resistant TP53 mutant AML cells. This concept warrants clinical evaluations. Citation Format: Bing Carter, Po Yee Mak, Wenjing Tao, Lauren B Ostermann, Yuki Nishida, Steffen Boettcher, Michael Andreeff. Targeting HSP90 epichaperome in TP53 mutant AML [abstract]. In: Proceedings of the AACR Special Conference: Acute Myeloid Leukemia and Myelodysplastic Syndrome; 2023 Jan 23-25; Austin, TX. Philadelphia (PA): AACR; Blood Cancer Discov 2023;4(3_Suppl):Abstract nr A08.

Danlou Tablet Protects Against Cardiac Remodeling and Dysfunction after Myocardial Ischemia/Reperfusion Injury through Activating AKT/FoxO3a Pathway.

Myocardial ischemia/reperfusion injury (I/RI) and ventricular remodeling are the critical pathological basis of heart failure. Danlou tablet (Dan) is a kind of Chinese patent medicine used in angina pectoris treatment in China. However, it remains unclear whether and how Dan could protect against cardiac remodeling after myocardial I/RI. In this study, both preventive and therapeutic administration of Dan attenuated ventricular remodeling and cardiac dysfunction at 3weeks after myocardial I/RI. Dan inhibited Bax/Bcl2 ratio and Caspase3 cleavage in heart tissues and also inhibited apoptosis of human AC16 cells and neonatal rat cardiomyocytes stressed by oxygen and glucose deprivation/reperfusion. Mechanistically, Dan inhibited myocardial apoptosis through phosphorylating AKT and FoxO3a, thereby inhibiting downstream BIM and PUMA expressions. Collectively, these results demonstrate that Dan treatment is effective to protect against cardiac remodeling and dysfunction after myocardial I/RI and provide theoretical basis for its cardioprotection and clinical application in treating ischemic cardiac diseases.

Abstract 6127: MDM2 inhibition in combination with MEK inhibition in pre-clinical models of lung adenocarcinomas with MDM2 amplification

Abstract The eventual development of resistance to single-agent targeted therapies in lung adenocarcinomas (LUAD) is inevitable, and new strategies are needed. We hypothesize that combination therapies aimed at a known driver and a distinct targetable alteration could prolong time on oral targeted therapy. In an analysis of 7636 patients with LUAD who underwent MSK-IMPACT large panel NGS testing, 5.5% (416/7636) harbored MDM2 amplification (MDM2amp), a known mechanism of TP53 inactivation. MDM2amp was over-represented among tumors with alterations in METex14 (34.4%, p&amp;lt;0.001), EGFR (10%, p&amp;lt;0.001), RET (11%, p&amp;lt;0.05), and ALK (9.9%, p&amp;lt;0.002). The small molecule MDM2 inhibitor milademetan (mila) caused growth inhibition as a single-agent in MDM2amp patient-derived cell lines with concurrent kinase alterations including ECLC5-GLx (MDM2amp/TRIM33::RET/TP53 wildtype (WT)) and LUAD12c (MDM2amp/METex14/KRASG12S/TP53 WT). Mila also caused growth inhibition in a cell line with KRASG12C and WT TP53 without MDM2amp (SW1573 (KRASG12C/TP53WT)), but not in cell lines with TP53 mutations (LUAD-002AS1 (KIF5B::RET/TP53P128fs, H1792 (KRASG12C/TP53 splice site mut)). Treatment of ECLC5-GLx and LUAD12c with mila resulted in restoration of ERK phosphorylation, confirming a previous report of ERK activation upon MDM2 inhibition. At 48 hours, ERK phosphorylation was suppressed by concurrent mila and MEK inhibition using trametinib (tram). In contrast, ERK phosphorylation was not suppressed by concurrent mila and KIF5B::RET inhibition using selpercatinib (in ECLC5-GLx) or MET inhibition using capmatinib (in LUAD12c). The combination of mila+tram was synergistic in slowing growth of ECLC5-GLx, LUAD12c, and SW1573 cells, and increased expression of pro-apoptotic proteins PUMA and BIM, beyond that achieved by either agent alone. In ECLC5-GLx, mila+tram also caused increased apoptotic cells measured by Annexin-V compared to either agent alone (combination p&amp;lt;0.01 compared to mila, p&amp;lt;0.001 compared to tram). In vivo, combination mila+tram was more effective than mila or tram alone in ECLC5-GLx (p&amp;lt;0.0001 and p&amp;lt;0.0001, respectively), LX-285 (EGFRex19del/MDM2amp) (p&amp;lt;0.0001 and p&amp;lt;0.0001, respectively), and L-13BS1 (model resistant to capmatinib) (METex14/MDM2amp) (p&amp;lt;0.05 and p&amp;lt;0.0001, respectively). These results suggest that combined MDM2/MEK inhibition is effective in patient-derived LUAD models harboring MDM2amp. This combination, potentially applicable to LUADs with a wide variety of oncogenic driver mutations and kinase fusions will be investigated as part of a phase 1/2 clinical trial. Citation Format: Arielle Elkrief, Vladimir Markov, Álvaro Quintanal-Villalonga, Rebecca Caeser, Pawel Sobczuk, Emily Cheng, Alexander Drilon, Gregory J. Riely, William W. Lockwood, Elisa de Stanchina, Charles M. Rudin, Igor Odintsov, Romel Somwar. MDM2 inhibition in combination with MEK inhibition in pre-clinical models of lung adenocarcinomas with MDM2 amplification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6127.

Abstract 1465: A SNAI2/CDKN1A pathway protects rhabdomyosarcoma tumors from radiation

Abstract Rhabdomyosarcoma (RMS) is tumor of the muscle and is the most common soft tissue cancer in children and teens, with approximately 400 to 500 new cases every year in the United States. There are two main subtypes of rhabdomyosarcoma: 1) Alveolar rhabdomyosarcoma (fusion-positive RMS FP-RMS), is classified primarily by the presence of the fusion between PAX3/PAX7 and FOXO1 proteins. 2) Embryonal rhabdomyosarcoma (fusion-negative FN-RMS) is the more common subtype. The survival rate for patients with RMS is 70%, but at relapse it is less than 30%. The standard of care for this disease includes radiation, chemotherapy and surgery. To better understand how RMS tumors survive therapy, we sought to define the role of SNAI2 in the response to radiation treatment. We identified SNAI2 as a critical oncogene that protects RMS tumors from radiation induced apoptosis by repressing pro-apoptotic BIM expression (Cancer Research 2021). SNAI2 additionally prevents FN-RMS tumors and cells from undergoing myogenic differentiation (Nature Comm. 2021). We also showed that MEK maintained SNAI2 post translationally in RAS mutant FN-RMS tumors and combining MEK inhibitor with radiation led to complete tumor regression and delayed event free survival in xenograft and PDX models. However, rare tumor cells grow back after a 2-4 weeks delay (Molecular Cancer Therapeutics, 2022). Hence, we hypothesized that there are additional genes or pathways in cells lacking SNAI2 that are co-opted to drive relapse disease. We have identified that CDKN1A or p21 expression is robustly increased in SNAI2 null cells. CDKN1A is thought to be a tumor suppressor in RMS and other cancers. However, our preliminary data indicate that CDKN1A is an oncogene and in RMS patients, high expression in tumors is associated with poor outcome. We found that p21 expression in combination with SNAI2 can predict resistance to radiation across RMS cell lines. We next developed control RD, Rh30 and Rh18 cells either CDKN1A or both CDKN1A and SNAI2 ablated using CRISPR/Cas9 reagents with control cells expressing control gRNAs. Ablation of CDKN1A while not effecting proliferation led to a significant increase in apoptosis post-radiation and this effect was increased in SNAI2/CDKN1A double knockout cells. Further, in colony forming assays we find that double ablated cells form significantly fewer colonies than control and single knockout cells. Rather unexpectedly, loss of CDKN1A, SNAI2, or CDKN1A/SNAI2 led to a G2/M cell cycle block, indicating that the cell cycle effects of p21 might not be responsible for the phenotypes observed. Ongoing xenograft experiments will determine if the effect we observe in vitro will also translate in vivo. Additionally, we are performing experiments to test how SNAI2 modulates CDKN1A expression. In summary, our study identifies CDKN1A as an oncogene that protects SNAI2 deficient cells from ionizing radiation, thus enabling the survival or rare relapse driving tumor cells. Citation Format: Paulomi S. Modi, Long Wang, Prethish Sreenivas, Myron Ignatius. A SNAI2/CDKN1A pathway protects rhabdomyosarcoma tumors from radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1465.