Alvocidib Potentiates the Activity of Venetoclax in Preclinical Models of Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1652-1652
Author(s):  
Clifford J. Whatcott ◽  
James M Bogenberger ◽  
Wontak Kim ◽  
Hillary Haws ◽  
Nanna Hansen ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Cell Viability ◽  
Cell Lines ◽  
Research Funding ◽  
Single Agent ◽  
Employment Equity ◽  
Fold Reduction ◽  
Remission Rates ◽  
Equity Ownership

Abstract Introduction Venetoclax (ABT-199) is an approved BCL-2 inhibitor for the treatment of patients with chronic lymphocytic leukemia (CLL). Multiple clinical trials are underway to explore its efficacy in additional indications. While venetoclax demonstrated high remission rates in combination with azacitidine in early stage clinical trials, the question of durability of responses and primary and acquired resistance remain, especially given the modest activity and rapid development of resistance as a single agent. One reported mechanism of intrinsic resistance is high expression of other BCL-2 family proteins, including MCL-1. We and others have demonstrated that the CDK9 inhibitor, alvocidib, can mediate transcriptional repression of anti-apoptotic MCL-1. It has also been shown that alvocidib can increase pro-apoptotic BIM, a dual activator and sensitizer BH3-only protein that can directly induce apoptosis and simultaneously inactivate anti-apoptotic BCL-2 family proteins such as MCL-1 and BCL-2, thus having the same effect on mitochondria-associated apoptosis as MCL-1 down-regulation, with the potential to directly induce apoptosis. An alvocidib-containing cytotoxic chemotherapy regimen demonstrated favorable remission rates in high-risk AML patients over standard therapy in a randomized Phase 2 trial indicating its potential role and safety in AML. We hypothesized that alvocidib and venetoclax would synergize against AML cells by shifting the overall balance of pro- and anti-apoptotic BCL-2 proteins in favor of apoptosis and thus represent a novel active treatment regimen in AML. Aims This study seeks to examine the efficacy of a treatment regimen containing alvocidib and venetoclax in multiple preclinical studies, including in vivo models of AML. Methods Cell viability assays interrogating alvocidib and venetoclax activity in cell lines were performed using CellTiter-Glo according to manufacturer's protocol. mRNA/miRNA expression changes were assessed using standard RT-PCR technique. Protein expression changes were assessed using standard western immunoblotting technique. To assess the efficacy of an alvocidib and venetoclax combination on tumor growth in an in vivo model, the OCI-AML3 xenograft mouse model and ex vivo studies with AML patient samples were performed. Results Herein we demonstrate that alvocidib inhibits both mRNA and protein expression of MCL-1 in a time and concentration-dependent fashion in 3 out of 4 AML cell lines analyzed, while in cells where alvocidib did not reduce MCL-1 protein levels (i.e. MOLM-13) a dose-dependent decrease in miR17-92, and concomitant increase in BIM protein was observed after 24 hours of alvocidib treatment. The alvocidib-venetoclax combination resulted in very strong synergistic reductions of cell viability (with combination indices [CI] of 0.4 to 0.7), both in venetoclax-sensitive and resistant cells. The venetoclax-sensitive lines, MV4-11 and MOLM-13, exhibited 5- to 10-fold reduction of venetoclax EC50 values in the low nM range when combined with only 80 nM alvocidib. Importantly, venetoclax-resistant lines, OCI-AML3 and THP-1, exhibited at least 20-fold reduction of venetoclax EC50 values from near 1 µM to 10-50 nM, when combined with 80 nM alvocidib.In the venetoclax-resistant OCI-AML3 xenograft model, single agent alvocidib and venetoclax achieved tumor growth inhibition (TGI) of 9.7 and 31.5%, respectively, while the combination achieved 87.9% TGI at the same dose levels of individual drugs. Conclusions Taken together, our data suggest that the combination of alvocidib with venetoclax is highly synergistic in vitro and in vivo, in both venetoclax-sensitive and -resistant AML across a heterogeneous genomic background. The particularly high level of synergy achieved in venetoclax-resistant cell lines highlights the central importance of both BCL-2 and MCL-1-mediated cell survival in AML. Importantly, the addition of alvocidib to venetoclax treatment reduced IC50s to clinically achievable concentrations. Therefore, we conclude that an alvocidib/venetoclax combination may be a novel approach for the treatment of AML and warrants further pre-clinical and clinical validation. Disclosures Whatcott: Tolero Pharmaceuticals: Employment. Kim:Tolero Pharmaceuticals: Employment. Haws:Tolero Pharmaceuticals: Employment. Mesa:Celgene: Research Funding; Galena: Consultancy; Promedior: Research Funding; Ariad: Consultancy; Novartis: Consultancy; CTI: Research Funding; Incyte: Research Funding; Gilead: Research Funding. Peterson:Tolero Pharmaceuticals: Employment. Siddiqui-Jain:Tolero Pharmaceuticals: Employment. Weitman:Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties. Warner:Tolero Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties.

Coltuximab Ravtansine (SAR3419) Demonstrates Enhanced Activity in Combination with Bendamustine, Gemcitabine and Novel Targeted Agents Such As PI3K Inhibitors in Pre-Clinical Models of Relapsed and/or Refractory Non-Hodgkins Lymphoma (NHL)

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5125-5125
Author(s):  
Callum M Sloss ◽  
Katie O'Callaghan ◽  
Jutta Deckert ◽  
Jenny Tsui ◽  
Leanne Lanieri ◽  
...  
Keyword(s):  
Cell Lines ◽  
Single Agent ◽  
Targeted Agents ◽  
Employment Equity ◽  
Pi3k Inhibitors ◽  
Xenograft Models ◽  
Equity Ownership ◽  
Chemotherapy Agents

Abstract Introduction: Relapsed/refractory B-cell NHL remains an area of significant medical need. CD19 is broadly expressed on B-cell malignancies making it an ideal target for antibody-drug conjugate (ADC) based therapy. Coltuximab ravtansine is a CD19-targeting ADC consisting of a CD19-targeting antibody conjugated to the maytansinoid anti-mitotic DM4. In preclinical studies, coltuximab ravtansine has shown potent, targeted activity against NHL cell lines and xenograft models. In early clinical trials, it has been well tolerated and has shown promising signs of efficacy as both a single agent and in combination with rituximab. In the STARLYTE Phase 2 trial coltuximab ravtansine monotherapy resulted in an ORR of 44% in R/R-DLBCL that included an ORR of 21% in hard-to-treat primary refractory patients (NCT01472887). Here we describe studies aimed at the identification of combination partners for coltuximab ravtansine to further optimize clinical benefit to R/R-NHL patients. We are employing a dual approach where we investigate combination of coltuximab ravtansine with multiple, novel targeted therapy partners whilst in parallel also investigating the combination of coltuximab ravtansine with chemotherapies commonly used in the late stage R/R-NHL setting. Methods: Coltuximab ravtansine and the DM4 payload were evaluated in a high throughput screen both as single agents and in combination with a selection of novel, emerging targeted agents across a panel of twenty NHL cell lines. The combinations were evaluated in a dose-response matrix and a statistical method was used to identify combination synergies significantly superseding baseline additivity values. The in vivo efficacy of coltuximab ravtansine was additionally assessed in combination with various clinically relevant chemotherapy agents in subcutaneous xenograft models of NHL. Results: Coltuximab ravtansine and DM4 both showed potent single agent activity against the entire panel of NHL cell lines with median GI50's of 770pM and 100pM, respectively. We observed a significant correlation in the cell line sensitivity of the two compounds suggesting that sensitivity to coltuximab ravtansine is driven, at least in part, by inherent sensitivity of cells to the cytotoxic effects of the DM4 payload. In vitro combination studies for coltuximab ravtansine were performed to identify targets or pathways that result in the most prominent combination effects across the cell line panel. Analysis of the in vitro combination dose-matrix revealed particularly strong synergy between coltuximab ravtansine and various inhibitors of the PI3K/AKT/mTOR axis. Studies to examine the synergism between coltuximab ravtansine and PI3K inhibitors in in vivo models of NHL are ongoing. In order to further determine the utility of coltuximab ravtansine as part of a potential combination regimen for the treatment of R/R-NHL, we assessed the combination of coltuximab ravtansine with the chemotherapy agents bendamustine and gemcitabine in vivo. As gemcitabine is typically used in combination we assessed the efficacy of a coltuximab ravtansine with rituximab and gemcitabine in vivo. In both cases the combination with coltuximab ravtansine was significantly more efficacious than the standard-of-care alone arms. Conclusions: Coltuximab ravtansine demonstrates synergistic activity in combination with multiple PI3K pathway inhibitors across a large panel of NHL cell lines. Additionally, we have shown that combination of coltuximab ravtansine with clinically relevant late stage treatments such as bendamustine and rituximab + gemcitabine is more efficacious than the chemotherapy regimens alone. These results support the continued development of coltuximab ravtansine in R/R-NHL in combination with chemotherapy regimens and suggest that a combination of coltuximab ravtansine with PI3K inhibitors may also be of interest in the clinical setting. Disclosures Sloss: ImmunoGen, Inc.: Employment, Equity Ownership. O'Callaghan:ImmunoGen, Inc.: Employment, Equity Ownership. Deckert:ImmunoGen, Inc.: Employment, Equity Ownership. Tsui:ImmunoGen, Inc.: Employment, Equity Ownership. Lanieri:ImmunoGen, Inc.: Employment, Equity Ownership. Romanelli:ImmunoGen, Inc.: Employment, Equity Ownership.

scholarly journals Targeting Wnt/β-Catenin and BCL-2, Two Critical Survival Factors, Synergistically Induces Apoptosis in AML Via Rac1-Mediated MCL-1 Inhibition

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1442-1442
Author(s):  
Xiangmeng Wang ◽  
Po Yee Mak ◽  
Wencai Ma ◽  
Xiaoping Su ◽  
Hong Mu ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Single Agent ◽  
Advisory Committees ◽  
Equity Ownership ◽  
Critical Survival

Abstract Wnt/β-catenin signaling regulates self-renewal and proliferation of AML cells and is critical in AML initiation and progression. Overexpression of β-catenin is associated with poor prognosis. We previously reported that inhibition of Wnt/β-catenin signaling by C-82, a selective inhibitor of β-catenin/CBP, exerts anti-leukemia activity and synergistically potentiates FLT3 inhibitors in FLT3-mutated AML cells and stem/progenitor cells in vitro and in vivo (Jiang X et al., Clin Cancer Res, 2018, 24:2417). BCL-2 is a critical survival factor for AML cells and stem/progenitor cells and ABT-199 (Venetoclax), a selective BCL-2 inhibitor, has shown clinical activity in various hematological malignancies. However, when used alone, its efficacy in AML is limited. We and others have reported that ABT-199 can induce drug resistance by upregulating MCL-1, another key survival protein for AML stem/progenitor cells (Pan R et al., Cancer Cell 2017, 32:748; Lin KH et al, Sci Rep. 2016, 6:27696). We performed RNA Microarrays in OCI-AML3 cells treated with C-82, ABT-199, or the combination and found that both C-82 and the combination downregulated multiple genes, including Rac1. It was recently reported that inhibition of Rac1 by the pharmacological Rac1 inhibitor ZINC69391 decreased MCL-1 expression in AML cell line HL-60 cells (Cabrera M et al, Oncotarget. 2017, 8:98509). We therefore hypothesized that inhibiting β-catenin by C-82 may potentiate BCL-2 inhibitor ABT-199 via downregulating Rac1/MCL-1. To investigate the effects of simultaneously targeting β-catenin and BCL-2, we treated AML cell lines and primary patient samples with C-82 and ABT-199 and found that inhibition of Wnt/β-catenin signaling significantly enhanced the potency of ABT-199 in AML cell lines, even when AML cells were co-cultured with mesenchymal stromal cells (MSCs). The combination of C-82 and ABT-199 also synergistically killed primary AML cells (P<0.001 vs control, C-82, and ABT-199) in 10 out of 11 samples (CI=0.394±0.063, n=10). This synergy was also shown when AML cells were co-cultured with MSCs (P<0.001 vs control, C-82, and ABT-199) in all 11 samples (CI=0.390±0.065, n=11). Importantly, the combination also synergistically killed CD34+ AML stem/progenitor cells cultured alone or co-cultured with MSCs. To examine the effect of C-82 and ABT-199 combination in vivo, we generated a patient-derived xenograft (PDX) model from an AML patient who had mutations in NPM1, FLT3 (FLT3-ITD), TET2, DNMT3A, and WT1 genes and a complex karyotype. The combination synergistically killed the PDX cells in vitro even under MSC co-culture conditions. After PDX cells had engrafted in NSG (NOD-SCID IL2Rgnull) mice, the mice were randomized into 4 groups (n=10/group) and treated with vehicle, C-82 (80 mg/kg, daily i.p injection), ABT-199 (100 mg/kg, daily oral gavage), or the combination for 30 days. Results showed that all treatments decreased circulating blasts (P=0.009 for C-82, P<0.0001 for ABT-199 and the combination) and that the combination was more effective than each single agent (P<0.001 vs C-82 or ABT-199) at 2 weeks of therapy. The combination also significantly decreased the leukemia burden in mouse spleens compared with controls (P=0.0046) and single agent treated groups (P=0.032 or P=0.020 vs C-82 or ABT-199, respectively) at the end of the treatment. However, the combination did not prolong survival time, likely in part due to toxicity. Dose modifications are ongoing. These results suggest that targeting Wnt/β-catenin and BCL-2, both essential for AML cell and stem cell survival, has synergistic activity via Rac1-mediated MCL-1 inhibition and could be developed into a novel combinatorial therapy for AML. Disclosures Andreeff: SentiBio: Equity Ownership; Oncolyze: Equity Ownership; Oncoceutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy; Amgen: Consultancy, Research Funding; Eutropics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Patents & Royalties: MDM2 inhibitor activity patent, Research Funding; Aptose: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Reata: Equity Ownership; Astra Zeneca: Research Funding; Celgene: Consultancy; United Therapeutics: Patents & Royalties: GD2 inhibition in breast cancer . Carter:novartis: Research Funding; AstraZeneca: Research Funding.

scholarly journals ASLAN003, a Novel and Potent Dihydroorotate Dehydrogenase (DHODH) Inhibitor, Induces Differentiation of Acute Myeloid Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4047-4047 ◽  
Author(s):  
Jianbiao Zhou ◽  
Jessie Yiying Quah ◽  
Jing Yuan Chooi ◽  
Sabrina Hui-Min Toh ◽  
Yvonne Ng ◽  
...  
Keyword(s):  
Cell Growth ◽  
Cell Lines ◽  
Research Funding ◽  
Tissue Bank ◽  
Dihydroorotate Dehydrogenase ◽  
Employment Equity ◽  
Healthy Control ◽  
Equity Ownership ◽  
Nbt Reduction

Abstract Background: Differentiation therapies achieve remarkable success in acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia (AML). However, clinical benefits of differentiation therapies are negligible in non-APL AML, which accounts for the majority of AML cases. Dihydroorotate dehydrogenase (DHODH) regulates the fourth step of the de novo pyrimidine synthesis pathway. DHODH is a key therapeutic target for auto-immune diseases and cancer, particularly differentiation of AML. ASLAN003 is a novel, potent small molecule DHODH inhibitor being developed in AML by ASLAN Pharmaceuticals. Methods: We investigated activity of ASLAN003 in AML cell lines and primary bone marrow (BM) cells (NUS Leukemia Tissue Bank) from patients with AML (N = 14) or myelodysplastic syndromes (MDS) (N = 6) and healthy control (N = 1). We performed CTG assay, FACS analysis of cell viability and myeloid markers, wright-giemsa staining, NBT reduction assay, and qRT-PCR analysis of key lineage transcription factors to evaluate the effects of ASLAN003 on cell growth, differentiation, apoptosis, and gene expression changes in vitro. Two AML cell lines and 1 leukemic patient derived xenograft (PDX) line (NUS Leukemia Tissue Bank) were studied in NSG xenograft mice. Mice were administrated with vehicle control or ASLAN003 50 mg/kg by oral gavage once daily. Results: ASLAN003 inhibited leukemic cell growth of THP-1, MOLM-14 and KG-1 with IC50 of 152, 582 and 382 nM, respectively, at 48 h. Treatment of these leukemia cells with ASLAN003 for 96 h consistently resulted in remarkable increase of CD11b (p < 0.001) and displayed morphologic changes of terminal differentiation and positivity for NBT reduction. ASLAN003 was active in differentiation with an EC50 of 28, 85, and 56 nM, in these 3 lines, respectively. ASLAN003 induced approximately 2-fold higher CD11b+ cells than Brequinar (BRQ), another DHODH inhibitor. Addition of uridine rescued differentiation and improved cell viability in ASLAN003 treated-cells, implying on-target specificity of ASLAN003. Mechanistically, ASLAN003 induced differentiation through induction of myeloid lineage transcription factor Runx1, Pu.1, Gif1 and repression of HoxA9, Gata1. The response of primary BM cells to ASLAN003 was classified into 3 categories: sensitive if any of myeloid markers CD11b, CD14, CD13 or CD33 increased ≥ 15%; moderate: ≥ 5%, but < 15%; resistant: < 5%. Among AML samples, we observed 6 (43%) sensitive cases, 6 (43%) moderate cases and 2 (14%) resistant cases. Three (50%) MDS samples displayed sensitive response and 3 cases (50%) showed moderate response. The healthy control sample was resistant to ASLAN003. Importantly, ASLAN003 promoted differentiation and cell death of myeloid cells in one relapsed AML case. Morphologic analysis and NBT assay demonstrated the features of neutrophil differentiation in selected ASLAN003-treated primary AML blasts. For in vivo experiments, significantly prolonged survival was seen in ASLAN003-treated groups when compared to vehicle control group in both MOLM-14 (p = 0.031) and THP-1 (p < 0.001) xenograft models. ASLAN003 substantially reduced disseminated tumors and leukemic infiltration into liver in xenografted mice. The human CD45+ cells were significantly reduced in BM, peripheral blood, spleen and liver, with significantly increased differentiation of AML cells (CD11b and CD14 positive cells) in BM of treated mice in both models (p < 0.01). We also evaluated the therapeutic efficacy of ASLAN003 in one PDX line, AML-14. At the end of experiments (day 77 post treatment), all PDX mice were alive in both control and ASLAN003 group. The leukemic burden was significantly lower in ASLAN003-treated PDXs than in vehicle-treated PDXs (p = 0.04). Overall, these data demonstrate potent in vivo efficacy of ASLAN003 in inducing myeloid differentiation of blast cells and the drug appears highly tolerable even after prolonged administration. Conclusion: ASLAN003 is a novel, highly potent DHODH inhibitor that induces terminal differentiation, inhibits cell growth and promotes cell death of AML blasts, including relapsed AML blasts. ASLAN003 prolongs survival and shows therapeutic effects in mice bearing different AML cell lines and reduces leukemic burden in an AML PDX model. Currently, ASLAN003 efficacy is being evaluated in a Phase IIa clinical trial in patients with AML (NCT03451084; Ting, ASH abstract 2018). Disclosures Seet: ASLAN Pharmaceuticals: Employment, Equity Ownership. Ooi:ASLAN Pharmaceuticals: Employment, Equity Ownership. Lindmark:ASLAN Pharmaceuticals: Employment, Equity Ownership. McHale:ASLAN Pharmaceuticals: Employment, Equity Ownership. Chng:Amgen: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Aslan: Research Funding; Merck: Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Celgene: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding.

Expression of Bcl-2 Pro-Survival Family Proteins Predicts Pharmacological Responses to ABT-199, a Novel and Selective Bcl-2 Antagonist, in Multiple Myeloma Models

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 5028-5028 ◽  
Author(s):  
Deepak Sampath ◽  
Elizabeth Punnoose ◽  
Erwin R. Boghaert ◽  
Lisa Belmont ◽  
Jun Chen ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Death ◽  
Cell Lines ◽  
Single Agent ◽  
Employment Equity ◽  
Bone Marrow Biopsies ◽  
Xenograft Models ◽  
Equity Ownership

Abstract Abstract 5028 Multiple myeloma (MM) is a hematological malignancy of the bone marrow caused by the dysregulated proliferation of monoclonal antibody producing plasma cells. A hallmark feature of cancer is the ability to evade cell death signals induced by stress response cues. The Bcl-2 family of proteins regulates the intrinsic apoptosis pathways and consists of pro-apoptotic (Bax, Bak, Bad, Bim, Noxa, Puma) and pro-survival (Bcl-2, Bcl-xL, Mcl-1); the balance of which dictates the life or death status of MM tumor cells. Thus, there is a strong rationale to target members of the Bcl-2 proteins for the treatment of MM. ABT-199 is a potent BH3-only mimetic that selectively antagonizes Bcl-2 and is currently in phase I clinical trials for the treatment of hematological malignancies. Therefore, we evaluated the efficacy of ABT-199 as a single agent and in combination with standard of care drugs such as Velcade (bortezomib) in preclinical models of MM. A panel of 21 human MM cell lines was evaluated in vitro for to sensitivity to ABT-199. ABT-199 potently inhibited cell viability in a sub-set of MM cell lines (7/21) with EC50 values less than 1 μM. Expression of Bcl-2, Bcl-xL, Mcl-1, Bim and other Bcl-2 family proteins were evaluated by protein and mRNA. Cell line modeling identified thresholds for expression of Bcl-2, Bcl-xL and Mcl-1 that best predicted sensitivity and resistance to ABT-199 and the dual Bcl-2/Bcl-xL antagonist, navitoclax. Consistent with the target inhibition profile of these drugs, we found that MM lines that were Bcl-2high/Bcl-xLlow/Mcl-1low are the most sensitive to ABT-199 treatment. Whereas cell lines that are Bcl-xLhigh remain sensitive to navitoclax but not ABT-199. MM cell lines that are Mcl-1high are less sensitive to both ABT-199 and navitoclax, suggesting that Mcl-1 is a resistance factor to both drugs. Utilizing a novel Mesoscale Discovery based immunoassay we determined that levels of Bcl-2/Bim complexes also correlated with sensitivity of ABT-199 in the MM cell lines tested. In addition, the t(11;14) status in these cell lines associated with sensitivity to ABT-199. The clinical relevance of the Bcl-2 pro-survival expression pattern in MM cell lines, was determined by a collection of bone marrow biopsies and aspirates (n=27) from MM patients by immunohistochemistry for prevalence of Bcl-2 and Bcl-xL. Similar to our in vitro observations, the majority (75%) of the MM bone marrow biopsies and aspirates had high Bcl-2 levels whereas 50% had high Bcl-xL expression. Therefore, a subset of patient samples (33%) were identified with a favorable biomarker profile (Bcl-2high/Bcl-xLlow) that may predict ABT-199 single agent activity. ABT-199 synergized with bortezomib in decreasing cell viability in the majority of MM cell lines tested in vitro based on the Bliss model of independence analyses (Bliss score range = 10 to 40). However the window of combination activity was reduced due to high degree of sensitivity to bortezomib alone. Therefore, the combination efficacy of ABT-199 and bortezomib was further evaluated in vivo in MM xenograft models that expressed high levels of Bcl-2 protein (OPM-2, KMS-11, RPMI-8226, H929 and MM. 1s). Bortezomib treatment alone at a maximum tolerated dose resulted in tumor regressions or stasis in all xenograft models tested. ABT-199 at a maximum tolerated dose was moderately efficacious (defined by tumor growth delay) as a single agent in xenograft models that expressed high protein levels of Bcl-2 but relatively lower levels of Bcl-xL. However, the combination of ABT-199 with bortezomib significantly increased the overall response rate and durability of anti-tumor activity when compared to bortezomib, resulting in increased cell death in vivo. Treatment with bortezomib increased levels of the pro-apoptotic BH3-only protein, Noxa, in MM xenograft models that expressed high levels of Mcl-1. Given that the induction of Noxa by bortezomib results in neutralization of Mcl-1 pro-survival activity in MM models [Gomez-Bougie et al; Cancer Res. 67:5418–24 (2007)], greater efficacy may be achieved when Bcl-2 is antagonized by ABT-199 thereby inhibiting pro-survival activity occurring through either Bcl-2 or Mcl-1 and increasing cell death. Thus, our preclinical data support the clinical evaluation of ABT-199 in combination with bortezomib in MM patients in which relative expression of the Bcl-2 pro-survival proteins may serve as predictive biomarkers of drug activity. Disclosures: Sampath: Genentech: Employment, Equity Ownership. Punnoose:Genentech: Employment, Equity Ownership. Boghaert:Abbott Pharmaceuticals: Employment, Equity Ownership. Belmont:Genentech: Employment, Equity Ownership. Chen:Abbott Pharmaceuticals: Employment, Equity Ownership. Peale:Genentech: Employment, Equity Ownership. Tan:Genentech: Employment, Equity Ownership. Darbonne:Genentech: Employment, Equity Ownership. Yue:Genentech: Employment, Equity Ownership. Oeh:Genentech: Employment, Equity Ownership. Lee:Genentech: Employment, Equity Ownership. Fairbrother:Genentech: Employment, Equity Ownership. Souers:Abbott Pharmaceuticals: Employment, Equity Ownership. Elmore:Abbott Pharmaceuticals: Employment, Equity Ownership. Leverson:Abbott Pharmaceuticals: Employment, Equity Ownership.

scholarly journals CC-92480, a Novel Cereblon E3 Ligase Modulator, Is Synergistic with Dexamethasone, Bortezomib, and Daratumumab in Multiple Myeloma

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1815-1815
Author(s):  
Lilly Wong ◽  
Rama Krishna Narla ◽  
Jim Leisten ◽  
Daniel Bauer ◽  
Matthew Groza ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Synergistic Effect ◽  
Cell Viability ◽  
Cell Lines ◽  
E3 Ligase ◽  
Proteasome Activity ◽  
Employment Equity ◽  
Equity Ownership

Introduction: CC-92480 is a novel cereblon E3 ligase modulator (CELMoD) with enhanced autonomous cell-killing and immunomodulatory activity against multiple myeloma (MM) cells. CC-92480 is currently in phase 1 development in a late-line myeloma patient population (NCT03374085). Here, we sought to characterize the antitumor activity of CC-92480 in combination with dexamethasone (DEX), bortezomib (BORT), or daratumumab (DARA) in MM cell lines in vitro and xenograft mouse models in vivo. Methods: CC-92480 activity in combination with DEX was evaluated in MM cell lines. Apoptosis was measured by quantification of caspase-3 activation. The effect of BORT on CC-92480-induced Ikaros and Aiolos degradation was determined by concurrent treatment of MM cells with BORT and CC-92480. β5-site proteasome activity was also determined in the same experiment. The in vitro activity of CC-92480 in combination with BORT was characterized using washout experiments to more faithfully model the short in vivo exposure but more prolonged, gradually diminishing proteasome inhibitory activity of BORT. Apoptosis and cell viability of CC-92480 with BORT were analyzed by flow cytometry. The effect of CC-92480 on CD38 expression was also evaluated across a panel of MM cell lines. The effect of CC-92480 in combination with DARA was characterized with antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) assays. CC-92480 in combination with DEX or BORT was tested in a lenalidomide-resistant (H929-1051) xenograft mouse model. Female SCID mice were inoculated with H929-1051 cells in the right hind leg. For the DEX combination, groups of tumor-bearing mice (n = 9-10) were dosed with vehicle, DEX, or CC-92480 once daily (QD), or CC-92480 in combination with DEX throughout the study, starting when the tumor volumes reached approximately 115 mm3. For combination with BORT, mice (n = 9-10/group) were dosed with vehicle, CC-92480, or BORT, or the CC-92480 and BORT combination starting when the tumor volumes reached approximately 500 mm3. CC-92480 was administered orally QD for 3 days and BORT as a single intravenous dose. Tumor volumes were measured twice a week for the duration of the studies. Results: CC-92480 synergized with DEX in reducing cell viability and potentiated DEX-induced apoptosis in a concentration-dependent manner in MM cell lines. Of note, the combination showed activity at concentrations of both DEX and CC-92480 that had minimal activity as single agents. In the xenograft model with H929-1051 cells, the combination of CC-92480 and DEX significantly inhibited tumor growth (−84%) when compared with either agent alone (−34% and −20% for CC-92480 and DEX, respectively) and was classified as a synergistic effect using the fractional product method. Although proteasome activity is required for CC-92480-induced degradation of Ikaros and Aiolos, CC-92480 nevertheless maintained its ability to efficiently degrade Ikaros and Aiolos in the presence of doses of BORT that cause clinically relevant levels of proteasome inhibition. The in vitro combination of CC-92480 with BORT resulted in greater cytotoxic activity on MM cells than either single agent alone. The in vivo efficacy of CC-92480 and BORT, administered concurrently, showed a strongly synergistic effect with a near complete or complete tumor regression in every animal, and 6 of 9 animals remained tumor-free through an observation period extending 157 days after the control group was terminated. Anti-CD38 therapies, including DARA and isatuxumab, target CD38-expressing MM cells for killing by immune cells through cytotoxic and phagocytic mechanisms. In a panel of MM cell lines, CC-92480 treatment caused increased cell surface expression of CD38 (2-3 times that of control). Pretreatment of MM cells with CC-92480 resulted in increased DARA-mediated ADCC and ADCP compared with DMSO-treated controls. Conclusions: The strong preclinical synergy in MM cell killing exhibited by CC-92480 in combination with DEX, BORT, and with an anti-CD38 antibody (DARA), highlights its potential to bring clinical benefit to patients with MM in combination with these agents and supports the rationale for testing these combinations in clinical studies. Disclosures Wong: Celgene Corporation: Employment, Equity Ownership. Narla:Celgene Corporation: Employment, Equity Ownership. Leisten:Celgene Corporation: Employment. Bauer:Celgene Corporation: Employment, Equity Ownership. Groza:Celgene Corporation: Employment, Equity Ownership. Gaffney:Celgene: Employment. Havens:Celgene: Equity Ownership; Pfizer: Employment, Equity Ownership. Choi:AnaptysBio Inc: Employment, Equity Ownership; Celgene Corporation: Equity Ownership, Other: Formerly Employed. Lopez-Girona:Celgene Corporation: Employment. Hansen:Celgene Corporation: Employment. Cathers:Celgene Corporation: Equity Ownership; Global Blood Therapeutics (GBT): Employment. Carmichael:Celgene plc: Employment, Equity Ownership. Pierce:Celgene Corporation: Employment, Equity Ownership.

Hodgkin's Lymphoma Cell Lines Have up-Regulated IL-3 Receptor α (IL-3Rα) Expression and Are Sensitive to SL-401, An IL-3Rα Targeted Drug,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3737-3737 ◽  
Author(s):  
Catherine S. Diefenbach ◽  
Rachel Sabado ◽  
Christopher L. Brooks ◽  
Jairo Baquero-Buitrago ◽  
Crystal Cruz ◽  
...  
Keyword(s):  
Cell Viability ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Lymphocytic Leukemia ◽  
High Expression ◽  
Cell Transplant ◽  
Second Line ◽  
Employment Equity ◽  
Equity Ownership

Abstract Abstract 3737 Background: Hodgkin lymphoma (HL) is among the most curable lymphomas, however 20%-30% of patients relapse after initial chemotherapy, or have primary refractory disease. While 30–50% of these patients may be cured with second line chemotherapy and autologous stem cell transplant, patients who do not obtain a complete response (CR) prior to transplantation, or who relapse after second line therapy have few effective therapeutic options. Novel treatment strategies for these patients are needed. It has been previously shown that in patients with classical HL the malignant Hodgkin Reed-Sternberg cells (HRS) express a high level of the Interleukin-3 receptor (IL-3R). Therefore, we hypothesized that SL-401, a novel biologic conjugate consisting of IL-3 linked to diphtheria toxin, which targets IL-3R, may be an effective approach for selectively targeting and killing HRS cells. Methods: We first assessed the expression of the IL-3R α-chain (CD123) on two nodular sclerosing (HDLM-2 and L-428) and two mixed cellularity (KM:H2 and L-1236) HL cell lines by flow cytometry. Cells were washed with PBS and stained with CD123 PE (BD Pharmingen) as well as other antibodies, including CD15 FITC (BD Pharmingen), for 20 minutes at 4°C and again washed with PBS. Stained cells were acquired using the LSR II (BD) and data were analyzed using Flow Jo (Tree Star). We then tested the sensitivity of these cell lines to SL-401 using a CellTiter Glo in vitro cytotoxicity assay. A CD123 positive eyrthroleukemic cell line (TF-1/H-ras) with known sensitivity to SL-401 was used as a positive control. The cell lines were cultured in the presence or absence of SL-401 for 48 h and assessed for cell viability at concentrations ranging from 3×10−7 to 1.3 μg/ml. Results: We found high expression of CD123 on HDLM-2 and L-428 HL lines (99% and 89%, respectively) and low-to-moderate expression of the receptor on the L1236 and KM-H2 lines (19.5% and 1%, respectively). Based on CD123 expression, we assessed the sensitivity of these cell lines to SL-401. The L428 and HDLM2 cell lines, which exhibited a high expression of CD123, showed sensitivity to SL-401 relative to control starting at approximately 0.3 ng/ml. Cell viability was reduced to 64.8 ± 5% for L-428 and 68.2 ± 8% for HDLM2 when incubated at the highest concentration of drug (1 μg/ml (L428) and 0.7 μg/ml (HDLM2)). The low CD123 expressing cell lines L1236 and KM:H2 were less sensitive to SL-401 and did not exhibit a significant reduction in cell viability even at the highest concentration of SL-401 tested (1.3 ug/ml; 100 ± 2% and 88.4 ± 6%, respectively). Other lymphoid malignant cell lines with CD123 expression reported in the literature were also tested. Interestingly, the T Acute Lymphocytic Leukemia (T-ALL) cell lines DND41 and P12 showed marked sensitivity to SL-401, with a reduction in cell viability to 55.9 ± 4% and 47.9 ± 6%, respectively, in the presence of 1.3 μg/ml of drug. Conclusion: These results suggest that CD123 expression may vary as a function of HL histology, and that sensitivity to SL-401 may correlate with CD123 expression. Based on these results, SL-401, which is currently being evaluated in clinical trials of patients with acute myeloid leukemia, myelodysplastic syndrome, and chronic myeloid leukemia, may be a potential treatment strategy in refractory HL, and warrants further exploration in T-ALL. Exploration of CD123 expression in primary and relapsed/refractory patients with lymphoid malignancies as well as in vivo studies with SL-401 in this setting is currently underway. Disclosures: Brooks: Stemline Therapeutics, Inc: Employment, equity options. Cirrito:Stemline Therapeutics Inc.: Employment, Equity Ownership, Patents & Royalties. Bergstein:Stemline Therapeutics Inc.: Employment, Equity Ownership, Patents & Royalties. O'Connor:Merck: Research Funding; Spectrum: Research Funding; Novartis: Research Funding; Celgene: Consultancy, Research Funding.

scholarly journals Single Agent and Combinatorial Efficacy of First-in-Class Small Molecule ONC201 in Acute Leukemia and Multiple Myeloma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2759-2759 ◽  
Author(s):  
Varun V Prabhu ◽  
Amriti Lulla ◽  
Christina L Kline ◽  
Peter J Van den Heuvel ◽  
Mala K. Talekar ◽  
...  
Keyword(s):  
Western Blot ◽  
Cell Viability ◽  
Cell Lines ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Single Agent ◽  
Employment Equity ◽  
Equity Ownership ◽  
Dose Dependent Decrease ◽  
Dose Dependent

Abstract ONC201 is the founding member of the imipridone class of anti-cancer small molecules that possess a unique core chemical structure. ONC201 is currently being evaluated in several Phase I/II clinical trials for advanced cancers. In the current study, we evaluated the single agent and combinatorial efficacy of ONC201 in preclinical models of acute leukemia and multiple myeloma (MM). In acute leukemia, we evaluated ONC201 anti-cancer effects in acute myeloid leukemia (AML) (Kasumi-1, HL60) and acute lymphoblastic leukemia (ALL) (Reh, Jurkat and MOLT-4) cell lines. We observed a time- and dose-dependent decrease in cell viability for every cell line in the panel (EC50 1-5 µM). Vincristine-resistant cells HL60/VCR were also sensitive to single agent ONC201 with EC50 values on par with corresponding vincristine-sensitive parental cells. Dose- and time-dependent induction of apoptosis was noted in Western blot analysis of caspase-3 cleavage in AML cell lines treated with 2.5 µM or 5 µM of ONC201 for 48 hr. Western Blot analysis further demonstrated inhibition of Akt and Foxo3a phosphorylation in Kasumi-1 cells, in line with the previously reported late-stage signaling effects of ONC201 in solid tumor cells (Allen et al, 2013). Sub-G1 analysis indicated that ONC201 induces apoptosis in ALL cells and a pan-caspase inhibitor reduced ONC201-mediated apoptosis. Western blot analysis revealed ONC201-mediated apoptosis involves PARP cleavage and caspase-9 activation in ALL cells. Anti-apoptotic Bcl-2 family members Bcl-2 and Bcl-xl were downregulated while the pro-apoptotic Bcl-2 family member Bim is upregulated in response to ONC201 treatment in ALL cells. ONC201 also downregulates the inhibitor of apoptosis (IAP) family proteins cIAP1 and cIAP2 in ALL cells. We observed inhibition of Akt phosphorylation upon ONC201 treatment of ALL cells. Fresh AML patient cells were also found to be sensitive to ONC201 in cell viability and caspase 3/7 activity assays at 5µM. We observed that independent clones of cancer cells with acquired resistance to ONC201 were more sensitive to cytarabine compared to parental ONC201-sensitive cancer cells. In addition, ONC201 demonstrated synergistic reduction in cell viability in combination with cytarabine in AML cell lines. Determination of combination indices (CI) revealed synergy at several concentrations (CI 0.336-0.75 in CMK cells). Also, ONC201 combined additively with midostaurin in CMK cells and vincristine in HL60/VCR cells. Thus, ONC201 is a promising combinatorial partner for AML therapies based on these preclinical sensitization results. In accordance with ONC201-mediated activation of the integrated stress response that B cells are highly sensitive to (Kline et al and Ishizawa et al, 2016), MM was identified as one of the most ONC201-sensitive tumor types in the Genomics of Drug Sensitivity in Cancer collection of cell lines. Three human MM cell lines were used for validation (KMS18, MM.1S and RPMI-8226), which revealed a time- and dose-dependent decrease in cell viability (EC50 1-2.5 µM). Bortezomib-resistant cells MM.1S 33X were sensitive to ONC201 as a single agent with EC50 values comparable to bortezomib-sensitive parental cells. We observed an average of 10-fold induction of ONC201-mediated apoptosis using Sub-G1 analyses in MM cells at 5 µM, 48 hrs post-treatment. Rescue of ONC201-mediated apoptosis was demonstrated using the pan-caspase inhibitor (Z-VAD-FMK). In addition, Western blot analysis in MM cells indicated a dose-dependent decrease in the anti-apoptotic protein XIAP which is a key mediator of apoptosis inhibition and is reported to be highly up-regulated in MM cells. Furthermore, ONC201 demonstrated synergistic reduction in cell viability at various concentrations in combination with either ixazomib or dexamethasone, which are used in the clinical treatment of MM, in RPMI8226 cells (CI 0.228-0.75). Also, ONC201 combined additively with bortezomib in RPMI8226 and MM.1S 33X cells. In summary, these preclinical studies support the ongoing ONC201 single agent trials in acute leukemias and MM. Our findings suggest that ONC201 may be an important therapeutic option for patients with hematological malignancies who have developed resistance to approved therapies. Additionally, our results point to specific standard-of-care therapies that may be combined with ONC201 to exert durable responses without adding to the burden of toxicity. Disclosures Prabhu: Oncoceutics: Employment. Tarapore:Oncoceutics: Employment, Equity Ownership. Oster:Oncoceutics: Employment, Equity Ownership. Allen:Oncoceutics: Employment, Equity Ownership. El-Deiry:Oncoceutics: Equity Ownership.

scholarly journals Preliminary Results from a Phase I Dose Escalation Trial of Ruxolitinib and the PI3Kδ Inhibitor TGR-1202 in Myelofibrosis

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1125-1125 ◽  
Author(s):  
Tamara K Moyo ◽  
Andrew Sochacki ◽  
Gregory D Ayers ◽  
Michael T. Byrne ◽  
Stephen A. Strickland ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Single Agent ◽  
Symptom Assessment ◽  
Akt Signaling ◽  
Employment Equity ◽  
Advisory Committees ◽  
Equity Ownership ◽  
Grade 3

Abstract Background: Therapies for myelofibrosis (MF) are limited and most are palliative. The JAK1/2 inhibitor ruxolitinib reduces spleen size and MF-related symptoms and improves survival, but can be limited by dose-dependent anemia and thrombocytopenia. Moreover, nearly half of ruxolitinib responders relapse within 5 years. PI3Kd is highly expressed in MF patient samples, independent of ruxolitinib pre-exposure. In JAK2-mutated cell lines, inhibition of PI3K/AKT signaling reduced proliferation and clonogenic potential. The once daily, next generation PI3Kd inhibitor TGR-1202 inhibited PI3K/AKT signaling and led to apoptosis in leukemia and lymphoma cell lines and was well-tolerated in clinical studies, with a toxicity profile distinct from that of ruxolitinib and other PI3Kd inhibitors. We hypothesized that adding TGR-1202 to ruxolitinib could resensitize or augment the response of MF patients with lost or suboptimal response to single-agent ruxolitinib. Objective: To assess safety of TGR-1202 in combination with ruxolitinib in MF patients Secondary Objectives: Hematologic response, symptom assessment Methods: MF patients who had sub-optimal responses to ruxolitinib continued their highest tolerated dose of ruxolitinib without change for ≥ 8 weeks, and were assigned to escalating doses of TGR-1202 in a standard 3+3 algorithm. Adverse events (AEs) were graded by NCI-CTCAE v4.03. Efficacy was assessed according to IWG-MRT consensus response criteria. Symptoms were assessed by the MPN symptom assessment form total symptom score (TSS). All patients received Pneumocystis pneumonia prophylaxis after cycle 1. Results: Eleven MF patients were enrolled and received 400 mg (n=3), 800 mg (n=6), or 600 mg TGR-1202 (n=2) daily. Nine were evaluable for response. Median age was 66y, 73% were male. All had ECOG PS 0-1. Five patients had mutations in JAK2, 4 in CALR, and 3 in MPL; these were mutually exclusive with exception of 1 patient with CALR and MPL mutations (Table 1). Median number of cycles of TGR-1202 + ruxolitinib treatment was 5 (1-13). Grade 2 anemia was the most common AE (Table 2). Two patients had asymptomatic Grade 3 elevations in amylase and lipase that persisted after drug was held, meeting criteria for dose limiting toxicities (DLTs) in 2 separate cohorts (TGR-1202 800mg+ruxolitinib 15mg BID and TGR-1202 800mg+ruxolitinib 10mg BID). Both patients had peak plasma TGR-1202 concentrations 1.5-2x higher than the other patients receiving 800mg TGR-1202, although steady-state levels were equivalent. The maximum tolerated dose (MTD) of TGR-1202 in combination with ruxolitinib was not established. Two patients went off-study due to AEs, and 3 due to progressive disease. One of 9 evaluable patients achieved complete remission and 7 had stable disease. Seven of the 9 evaluable patients had improvement in hematologic parameters and 8 had reduced MF symptoms with a median 33% decrease in TSS (Fig. 1). Conclusions: TGR-1202 + ruxolitinib was well-tolerated. Pharmacokinetic data were consistent with single-agent TGR-1202 (unpublished data), indicating that ruxolitinib does not alter absorption or metabolism of TGR-1202. Grade 3 elevations in amylase and lipase were considered DLTs, per protocol. Although the clinical significance of these asymptomatic laboratory findings is not clear, the protocol was amended to further assay these labs and to exclude concomitant medications with the potential to increase amylase/lipase. Importantly, no grade ≥3 hepatotoxicity, colitis, or thrombocytopenia was seen and no MTD was found. Although only one patient achieved CR, 89% demonstrated clinical benefit with the addition of TGR-1202 to ruxolitinib, supporting further exploration of this combination. Disclosures Strickland: Alexion Pharmaceuticals: Consultancy; Ambit: Consultancy; Baxalta: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sunesis Pharmaceuticals: Consultancy, Research Funding; Abbvie: Research Funding; Astellas Pharma: Research Funding; Celator: Research Funding; Cyclacel: Research Funding; GlaxoSmithKline: Research Funding; Karyopharm Therapeutica: Research Funding; Sanofi: Research Funding. Miskin:TG Therapeutics, Inc: Employment, Equity Ownership. Cavers:TG Therapeutics: Employment, Equity Ownership. Sportelli:TG Therapeutics, Inc.: Employment, Equity Ownership. Michaelis:Pfizer: Equity Ownership; Cellgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte Corporation: Consultancy, Honoraria. Mesa:CTI: Research Funding; Promedior: Research Funding; Celgene: Research Funding; Gilead: Research Funding; Incyte: Research Funding; Galena: Consultancy; Ariad: Consultancy; Novartis: Consultancy. Savona:Amgen Inc.: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Research Funding; Ariad: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Sunesis: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees.

scholarly journals SM09419, a Novel, Small-Molecule CDC-like Kinase (CLK) Inhibitor, Demonstrates Strong Inhibition of the Wnt Signaling Pathway and Antitumor Effects in FMS-like Tyrosine Kinase 3 (FLT3)-Mutant Acute Myeloid Leukemia Models

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1377-1377 ◽  
Author(s):  
Heekyung Chung ◽  
Emily Creger ◽  
Lauren Sitts ◽  
Kevin Chiu ◽  
Chi-Ching Mak ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Cell Lines ◽  
Tumor Regression ◽  
Single Agent ◽  
Wnt Signaling Pathway ◽  
Antitumor Effects ◽  
Employment Equity ◽  
Equity Ownership

Acute myeloid leukemia (AML) with the FLT3 internal tandem duplication (FLT3-ITD) mutation accounts for ~25% of all AMLs, carries a poor prognosis, and is prone to relapse despite targeted therapy. FLT3 mutations are associated with aberrant activation of the Wnt signaling pathway, which itself is implicated in AML initiation/progression and is required for the self-renewal and survival of leukemic stem cells. CLKs regulate the activity of serine/arginine-rich splicing factors (SRSFs) that modulate spliceosome assembly, mRNA splicing, and gene expression. SM09419 is a novel, oral, small-molecule pan-CLK inhibitor that potently inhibits the Wnt pathway. These studies examined the antitumor activity of SM09419 as a single agent and in combination with targeted and standard therapies in preclinical models of FLT3-ITD AML. In MV-4-11 and MOLM-13 AML cells carrying the FLT3-ITD mutation, SM09419 dose-dependently inhibited SRSF6 phosphorylation and potently suppressed expression of Wnt pathway-related genes (CCND1, MYC, TCF7, DVL2). The effect on cell proliferation was tested in 8 AML cell lines with varying mutation profiles as well as 26 different leukapheresis-derived primary human AML cells. Proliferation was strongly impaired by SM09419 across all tested cell lines (average EC50=0.2 + 0.048 µM]); MV-4-11 and MOLM-13 cells had EC50 of 0.049 and 0.144 µM, respectively. SM09419 also potently inhibited proliferation in all primary AML cells (average EC50=0.048 + 0.0097 µM) regardless of FLT3 mutation status, cytogenetics, or AML diagnosis (de novo or relapsed/refractory). SM09419 also induced apoptosis in MV-4-11 and MOLM-13 cells, increasing caspase 3/7 activation and PARP cleavage while reducing survivin and MCL-1 expression relative to vehicle. In vivo antitumor effects and tolerability of oral SM09419 (QD) alone or combined with either midostaurin (FLT3 inhibitor) or venetoclax (BCL2 inhibitor) and/or azacitidine were assessed in FLT3-ITD xenograft models (n=5-6/group). In MOLM-13 xenografts, SM09419 (12.5 and 25 mg/kg) induced strong tumor growth inhibition (TGI) vs. vehicle at Day 14 (TGI 52% [p&lt;0.05] and 74% [p&lt;0.001], respectively). Midostaurin (50 mg/kg) induced significant TGI vs. vehicle (50%, p&lt;0.05), which was increased when administered in combination with 12.5 mg/kg SM09419 (81%, p&lt;0.001). In MV-4-11 xenografts, single-agent SM09419 (6.25, 12.5, and 25 mg/kg) induced significant TGI vs. vehicle (56% [p&lt;0.05], 94%, and 95% [p&lt;0.001], respectively) at Day 26 with tumor regression in all mice dosed at 12.5 mg/kg and 25 mg/kg. In a subsequent experiment, midostaurin (50 mg/kg) alone and combined with 6.25 mg/kg SM09419 for 23 days induced tumor regression in MV-4-11 xenografts (100% TGI vs. vehicle, p&lt;0.0001). After treatment discontinuation, tumor regression was maintained in all mice (6/6) treated with the combination for 26 days, whereas tumor regrowth was immediately observed in midostaurin-treated mice. In another MV-4-11 xenograft study, the combination of 6.25mg/kg SM09419 with azacitidine (0.8 mg/kg QD) and/or venetoclax (25 mg/kg QD) induced significant TGI (95-98% vs. vehicle, p&lt;0.001) with tumor regression at Day 26. Azacitidine + venetoclax induced 79% TGI (p&lt;0.001), but no tumor regression was observed. The triple combination induced tumor regression in all mice and complete regressions in 4/6 mice (67%); it had a greater effect on slowing tumor regrowth after treatment discontinuation vs. a single agent or doublet. SM09419 alone or in combination was well tolerated in these xenograft models based on body weight measurements. In summary, SM09419 potently inhibited SRSF6 phosphorylation and Wnt signaling pathway activity and induced apoptosis in FLT3-ITD cell lines. It also inhibited proliferation in cell lines and primary AML cells regardless of FLT3 status. The strong in vivo antitumor effects observed as combination treatment suggest that SM09419 combined with standard therapies may provide a clinical benefit by slowing or preventing relapse in AML with a marker of poor prognosis such as FLT3-ITD. A Phase 1 study assessing safety, tolerability, and pharmacokinetics of SM09419 in subjects with advanced hematologic malignancies is being initiated. Disclosures Chung: Samumed, LLC: Employment, Equity Ownership. Creger:Samumed, LLC: Employment, Equity Ownership. Sitts:Samumed, LLC: Employment, Equity Ownership. Chiu:Samumed, LLC: Employment, Equity Ownership. Mak:Samumed, LLC: Employment, Equity Ownership. KC:Samumed, LLC: Employment, Equity Ownership. Tam:Samumed, LLC: Employment, Equity Ownership. Bucci:Samumed, LLC: Employment, Equity Ownership. Stewart:Samumed, LLC: Employment, Equity Ownership. Phalen:Samumed, LLC: Employment, Equity Ownership. Cha:Samumed, LLC: Employment, Equity Ownership.

GSK-3 Spatial Regulation Has an Essential Role in Lenalidomide Activity and Represents a Biomarker of Clinical Response in CLL

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1793-1793 ◽  
Author(s):  
Suzanne Trudel ◽  
Sam Scanga ◽  
Fabrizio G Mastronardi ◽  
Ellen Nong Wei ◽  
Frank Mercurio ◽  
...  
Keyword(s):  
Research Funding ◽  
Single Agent ◽  
Objective Response ◽  
Predictive Biomarker ◽  
Membrane Localization ◽  
Employment Equity ◽  
Myeloma Cells ◽  
Spatial Regulation ◽  
Equity Ownership

Abstract Abstract 1793 Thalidomide (THAL) and IMID® immunomodulary drugs lenalidomide (LEN) and (POM) have proven beneficial in the treatment of a variety of hematological malignancies. Pre-clinical studies demonstrate multiple direct and indirect anti-tumor activities including anti-angiogeneic, proapoptotic, anti-proliferative and immunomodulatory effects. Recent studies have identified cerebron (CRBN) as a potential direct physical target of THAL and IMiD compounds and CRBN expression is reportedly required for IMiD compound activity. However, the precise link between CRBN and IMiD compound mechanism of action (MOA) have not been clearly defined. We applied Drosophila as a drug discovery platform to assess the MOA of THAL and IMiD compounds in vivo. THAL or POM fed Drosophila demonstrate morphological phenotypes that replicate wingless (wg) mutants indicating that drugs are inhibitors of Wg/Wnt signaling. In this model system, THAL and IMiD compounds disrupt membrane localization of GSK-3 indicating that the bioactivity of IMiD compounds is achieved through spatial regulation and potentiation of Sgg/GSK-3 in Drosophila. Using epistasis analysis we show that Drosophila expressing genetic mutants lacking GSK-3 activity and myeloma cells in which GSK-3a and GSK-3b have been knocked down by siRNA fail to respond to POM. In both Drosophila and myeloma cells therefore it appears that GSK-3 activity is required for biological responses. To test the clinical validity of GSK-3 as a biomarker, we obtained patient tumor samples from a Phase II clinical trial of single agent LEN for previously untreated CLL (Chen CI et al., J Clin Oncol, 2011; 29:1175). Twenty five patients were enrolled onto this study and received LEN at a starting dose of 2.5 mg days 1–21 of a 28 day cycle with monthly escalation to a target dose of 10 mg. The primary clinical endpoint for the trial was objective response to lenalidomide (complete response (CR) and partial response (PR)) evaluated as defined in the revised 1996 NCI Working Group guidelines. Peripheral blood samples for correlative studies were collected on days 1 (pre-dosing) and 8 of cycles 1 and 2. CRBN expression was evaluated by gene expression profiling and Western blot and found to be uniformly expressed in all 19 evaluable day 1 patient samples regardless of LEN response. Thus CRBN expression does not appear to be a useful predictive biomarker of response in this population of previously untreated patients. However, GSK-3 localization was correlated with response. Paired analysis of CD19 selected CLL cells comparing day 1 vs day 8 revealed focal membrane localization of GSK-3 on day 1 and subcellular redistribution on day 8 in 11 out of 12 evaluable responders (PR or better). By contrast, in the CLL cells from all 6 evaluable non-responders, GSK-3 expression appeared diffusely distributed before and after treatment. In preliminary studies using confocal immunofluorescence microscopy we determined that CRBN and GSK-3 co-localize in day 1 CLL samples of responders but not in those of non-responders. In summary, our results indicate that THAL and the IMiD compounds target GSK-3 function by spatial regulation and identify GSK-3 localization as a potential clinical biomarker of IMiD response. Disclosures: Trudel: Celgene: Honoraria; GlaxoSmithKline: Research Funding; Janssen: Honoraria. Mercurio:Celgene: Equity Ownership, Research Funding. Lopez-Girona:Celgene Corp: Employment, Equity Ownership. Gaidarova:Celgene Corp: Employment, Equity Ownership. Webb:Celgene: Employment, Equity Ownership. Chen:Johnson & Johnson: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; GlaxoSmithKline: Research Funding; Lundbeck: Consultancy. Stewart:Millenium: Consultancy, Honoraria, Research Funding; Onyx: Consultancy; Celgene: Consultancy. Manoukian:Celgene: Research Funding.

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