Activity In Mantle Cell Lymphoma Research Articles

Blockage of BCL-XL overcomes venetoclax resistance across BCL2+ lymphoid malignancies irrespective of BIM status

AbstractVenetoclax (VEN), a B-cell lymphoma 2 (BCL2) inhibitor, has a promising single-agent activity in mantle cell lymphoma (MCL), acute lymphoblastic leukemia (ALL), and large BCLs, but remissions were generally short, which call for rational drug combinations. Using a panel of 21 lymphoma and leukemia cell lines and 28 primary samples, we demonstrated strong synergy between VEN and A1155463, a BCL-XL inhibitor. Immunoprecipitation experiments and studies on clones with knockout of expression or transgenic expression of BCL-XL confirmed its key role in mediating inherent and acquired VEN resistance. Of note, the VEN and A1155463 combination was synthetically lethal even in the cell lines with lack of expression of the proapoptotic BCL2L11/BIM and in the derived clones with genetic knockout of BCL2L11/BIM. This is clinically important because BCL2L11/BIM deletion, downregulation, or sequestration results in VEN resistance. Immunoprecipitation experiments further suggested that the proapoptotic effector BAX belongs to principal mediators of the VEN and A1155463 mode of action in the BIM-deficient cells. Lastly, the efficacy of the new proapoptotic combination was confirmed in vivo on a panel of 9 patient–derived lymphoma xenografts models including MCL (n = 3), B-ALL (n = 2), T-ALL (n = 1), and diffuse large BCL (n = 3). Because continuous inhibition of BCL-XL causes thrombocytopenia, we proposed and tested an interrupted 4 days on/3 days off treatment regimen, which retained the desired antitumor synergy with manageable platelet toxicity. The proposed VEN and A1155463 combination represents an innovative chemotherapy-free regimen with significant preclinical activity across diverse BCL2+ hematologic malignancies irrespective of the BCL2L11/BIM status.

SOX11 is a novel binding partner and endogenous inhibitor of SAMHD1 ara-CTPase activity in mantle cell lymphoma

AbstractSterile alpha motif and histidine-aspartate (HD) domain–containing protein 1 (SAMHD1) is a deoxynucleoside triphosphate triphosphohydrolase with ara-CTPase activity that confers cytarabine (ara-C) resistance in several hematological malignancies. Targeting SAMHD1’s ara-CTPase activity has recently been demonstrated to enhance ara-C efficacy in acute myeloid leukemia. Here, we identify the transcription factor SRY-related HMG-box containing protein 11 (SOX11) as a novel direct binding partner and first known endogenous inhibitor of SAMHD1. SOX11 is aberrantly expressed not only in mantle cell lymphoma (MCL), but also in some Burkitt lymphomas. Coimmunoprecipitation of SOX11 followed by mass spectrometry in MCL cell lines identified SAMHD1 as the top SOX11 interaction partner, which was validated by proximity ligation assay. In vitro, SAMHD1 bound to the HMG box of SOX11 with low-micromolar affinity. In situ crosslinking studies further indicated that SOX11-SAMHD1 binding resulted in a reduced tetramerization of SAMHD1. Functionally, expression of SOX11 inhibited SAMHD1 ara-CTPase activity in a dose-dependent manner resulting in ara-C sensitization in cell lines and in a SOX11-inducible mouse model of MCL. In SOX11-negative MCL, SOX11-mediated ara-CTPase inhibition could be mimicked by adding the recently identified SAMHD1 inhibitor hydroxyurea. Taken together, our results identify SOX11 as a novel SAMHD1 interaction partner and its first known endogenous inhibitor with potentially important implications for clinical therapy stratification.

SOX11 is a novel binding partner and endogenous inhibitor of SAMHD1 ara-CTPase activity in mantle cell lymphoma.

The sterile alpha motif and histidine-aspartate (HD) domain containing protein 1 (SAMHD1) is a deoxynucleoside triphosphate triphosphohydrolase with ara-CTPase activity that confers cytarabine (ara-C) resistance in several haematological malignancies. Targeting SAMHD1's ara-CTPase activity has recently been demonstrated to enhance ara-C efficacy in acute myeloid leukemia. Here, we identify the transcription factor SRY-related HMG-box containing protein 11 (SOX11) as a novel direct binding partner and first known endogenous inhibitor of SAMHD1. SOX11 is aberrantly expressed not only in mantle cell lymphoma (MCL), but also in some Burkitt lymphomas. Co-immunoprecipitation of SOX11 followed by mass spectrometry in MCL cell lines identified SAMHD1 as the top SOX11 interaction partner which was validated by proximity ligation assay. In vitro, SAMHD1 bound to the HMG box of SOX11 with low-micromolar affinity. In situ crosslinking studies further indicated that SOX11-SAMHD1 binding resulted in a reduced tetramerization of SAMHD1. Functionally, expression of SOX11 inhibited SAMHD1 ara-CTPase activity in a dose-dependent manner resulting in ara-C sensitization in cell lines and in a SOX11-inducible mouse model of MCL. In SOX11-negative MCL, SOX11-mediated ara-CTPase inhibition could be mimicked by adding the recently identified SAMHD1 inhibitor hydroxyurea. Taken together, our results identify SOX11 as a novel SAMHD1 interaction partner and its first known endogenous inhibitor with potentially important implications for clinical therapy stratification.

Dual Targeting of ROR1 and BTK Augments the Anti-Lymphoma Activity in Mantle Cell Lymphoma

Background Mantle cell lymphoma (MCL) is a rare and aggressive subtype of non-Hodgkin lymphoma. Development of BTK inhibitors (BTKis) and CAR-T cells revolutionized the treatment paradigm for the patients with MCL. However, this aggressive B-cell lymphoma frequently relapses leading to poor survival. Therefore, novel therapies are in urgent need to overcome the therapeutic resistance. ROR1 is normally expressed during embryonic development but is usually absent or expressed at low levels in adult tissues. However, re-expression of ROR1 was found in various types of cancer, especially in cancer stem/tumor-initiating cells. ROR1 persistently activates oncogenic signaling pathways in the BCR/BTK-independent manner. Accordingly, we hypothesize that dual targeting of ROR1 and BTK may augment the therapeutic efficacy, and thus combination of monoclonal antibody zilovertamab (cirmtuzumab) targeting ROR1, and BTKis will overcome the therapeutic resistance and effectively kill the relapsed/refractory MCL cells. Methods A panel of MCL cell lines and primary patient samples were used in this study. ROR1 expression levels in MCL cell lines and primary MCL samples were determined by flow cytometry and western blotting. For establishment of patient-derived organoid (PDO), the patient samples or MCL cell from PDX tumors were resuspended in culture medium containing cytokine cocktails. The cell aggregates within 50% Matrigel were gently transferred into multiple-well plates as needed. The established PDOs were applied for drug sensitivity assays. In addition, a patient-derived xenograft (PDX) mouse model was also used for evaluating single agent and combination efficacy of BTKis and zilovertamab (Zilo). Cell viability assays were performed using CellTiter routine or 3D cell viability assay kit (Promega). Results We hypothesize dual targeting of both BTK and ROR1 signaling pathways will augment cytotoxic effect on the MCL cells including major proliferative and minor ROR1 +CD117 + population, whose survival is not dependent on BTK, in tumor mass. To test the hypothesis, we first analyzed the ROR1 expression in MCL cell lines, primary and PDX MCL cells using flow cytometry and immunoblotting analysis. Our results indicated that in comparison with normal PBMC, ROR1 expression were detected in all examined MCL cell lines including JeKo-1, Mino, Z-138, Granta519, JVM2, SP49, Maver-1 and Rec-1. To test whether p53 status relates to sensitivity of MCL cells to BTKi and Zilo, we examined cytotoxic effect of combination of BTKi and Zilo on MCL cell lines (1) harboring mutated TP53 (T P53 Mut): JeKo-1, JeKo-R, Mino, and Mino-R and (2) harboring wild-type TP53 ( TP53 WT): Z-138 and Maver-1, and PDO as well as PDX tumors derived from biopsies bearing either TP53 WT or TP53 Mut. Treatment with single BTKi at 2-10 µM (Ibrutinib, zanubrutinib, acalabrutinib or pirtobrutinib) significantly induced cytotoxicity in the TP53 MutMCL cells, and the cell death was remarkedly increased when BTKi was combined with Zilo at 25-50 µg/ml. In contrast, in MCL cell lines with TP53 WT, BTKi-Zilo combination did not significantly result in increase of cytotoxic effect compared to single agents. These results suggest that the genetic status of TP53 is important for the augmented cytotoxic effect of BTKi-Zilo combination on MCL cells. To further evaluate potentiated effect of BTKi-Zilo combination, we performed ex vivo viability assay using PDO platform. Typically, PDOs were treated with either single agent or combined regimens. Consistent with the data in MCL cell lines, BTKi-Zilo combination resulted in potentiated cytotoxic activity in the PDO models derived from naïve and relapsed patients harboring TP53 Mut. Furthermore, BTKi-Zilo combination displayed synergistic effect in a PDX model derived from a patient harboring TP53 Mut. Conclusion Dual targeting of BTK and ROR1 signaling pathways augmented efficacy selectively in preclinical MCL models with TP53 Mut. These data provide insights to develop tailored therapeutics to improve patient outcome for patients with TP53 mutation.

Novel 1,3,4-trisubstituted pyrazolopyrimidine derivatives show potent antiproliferative activity in mantle cell lymphoma

Background: Pyrazolopyrimidine scaffold is an important pharmacophore in drug discovery. This pharmacophore has been reported to produce numerous biological activities, of which anticancer is an important one. The development of novel pyrazolopyrimidine derivatives is of great importance for antitumor drug research. Objective: Compound 6, a pyrazolopyrimidine derivative reported by our group, showed weak antiproliferative activity with IC50 values of over 30 μM against mantle cell lymphoma (MCL) cell lines. In this study, we will further perform the structural optimization of compound 6 to screen highly active pyrazolopyrimidine derivatives. Methods: A novel series of 1,3,4-trisubstituted pyrazolopyrimidine derivatives were synthesized and their structures were elucidated by 1H-NMR, 13C-NMR, and HRMS. The antiproliferative activities of target compounds against MCL cell lines (Mino, Jeko-1, and Z138) were evaluated by the CellTiter-Glo luminescent cell viability assay. The effect of representative compounds to induce apoptosis was evaluated by Annexin V/Propidium Iodide (PI)-binding assay. Mitochondrial membrane potential and reactive oxygen species (ROS) levels in 15c-treated Z138 cells were tested by JC-1 and DCFH-DA probes, respectively. Results: Most compounds demonstrated improved antiproliferative activity against MCL cell lines compared to the lead compound 6, especially 15c, 15f, 15g, 15j, and 15o, with IC50 values at low micromolar levels. In addition, compound 15c could induce apoptosis in a dose-dependent manner in Z138 cells through reduction of mitochondrial membrane potential and enhancing reactive oxygen species production. Conclusion: The results showed that 1,3,4-trisubstituted pyrazolopyrimidine derivatives could be valuable lead compounds for the further development of anti-lymphoma agents.

P53 directly downregulates the expression of CDC20 to exert anti-tumor activity in mantle cell lymphoma

BackgroundCell cycle dysregulation characterized by cyclin D1 overexpression is common in mantle cell lymphoma (MCL), while mitotic disorder was less studied. Cell division cycle 20 homologue (CDC20), an essential mitotic regulator, was highly expressed in various tumors. Another common abnormality in MCL is p53 inactivation. Little was known about the role of CDC20 in MCL tumorigenesis and the regulatory relationship between p53 and CDC20 in MCL.MethodsCDC20 expression was detected in MCL patients and MCL cell lines harboring mutant p53 (Jeko and Mino cells) and wild-type p53 (Z138 and JVM2 cells). Z138 and JVM2 cells were treated with CDC20 inhibitor apcin, p53 agonist nutlin-3a, or in combination, and then cell proliferation, cell apoptosis, cell cycle, cell migration and invasion were determined by CCK-8, flow cytometry and Transwell assays. The regulatory mechanism between p53 and CDC20 was revealed by dual-luciferase reporter gene assay and CUT&Tag technology. The anti-tumor effect, safety and tolerability of nutlin-3a and apcin were investigated in vivo in the Z138-driven xenograft tumor model.ResultsCDC20 was overexpressed in MCL patients and cell lines compared with their respective controls. The typical immunohistochemical marker of MCL patients, cyclin D1, was positively correlated with CDC20 expression. CDC20 high expression indicated unfavorable clinicopathological features and poor prognosis in MCL patients. In Z138 and JVM2 cells, either apcin or nutlin-3a treatment could inhibit cell proliferation, migration and invasion, and induce cell apoptosis and cell cycle arrest. GEO analysis, RT-qPCR and WB results showed that p53 expression was negatively correlated with CDC20 expression in MCL patients, Z138 and JVM2 cells, while this relationship was not observed in p53-mutant cells. Dual-luciferase reporter gene assay and CUT&Tag assay revealed mechanistically that CDC20 was transcriptionally repressed by p53 through directly binding p53 to CDC20 promoter from − 492 to + 101 bp. Moreover, combined treatment of nutlin-3a and apcin showed better anti-tumor effect than single treatment in Z138 and JVM2 cells. Administration of nutlin-3a/apcin alone or in combination confirmed their efficacy and safety in tumor-bearing mice.ConclusionsOur study validates the essential role of p53 and CDC20 in MCL tumorigenesis, and provides a new insight for MCL therapeutics through dual-targeting p53 and CDC20.

314 (PB094) - Loss of RHOA impairs lenalidomide antitumor activity in mantle cell lymphoma

Background: Mantle cell lymphoma (MCL) is a rare, aggressive and incurable subtype of B-cell non-Hodgkin lymphoma (NHL) with a median overall survival of 5–7 years. Lenalidomide is an immunomodulatory agent, with clinical activity in relapsed or refractory (R/R) MCL patients. Among other effects, lenalidomide is known to enhance the formation of immunological synapses between MCL and lytic T/natural killer (NK) cells. The small GTPase Ras homolog family member A (RHOA) acts as a molecular switch controlling a wide variety of cellular processes such as cytoskeleton organization, cell proliferation, differentiation and migration.

Design and synthesis of novel pyrazolopyrimidine-based derivatives as reversible BTK inhibitors with potent antiproliferative activity in mantle cell lymphoma

Development of Bruton’s tyrosine kinase (BTK) inhibitors is of great value and significance in the treatment of B-cell malignancies and autoimmune diseases. Herein, a novel class of pyrazolopyrimidine-based BTK inhibitors were designed and evaluated in mantle cell lymphoma (MCL) cell lines. We demonstrated that target compounds had made great progress in improvement of antiproliferative activity compared to lead compound. Compounds 13c, 13g, 13h, 13l, 13n and 13o demonstrated effectively antiproliferative activity in MCL cells lines with single-digit micromolar potency. Furthermore, compound 13l specifically disturbed mitochondrial membrane potential and increased reactive oxygen species level in Z138 cells in a dose-dependent manner. 13l induced cell apoptosis through the caspase 3- mediated apoptotic pathway in Z138 cells. Overall, this study provides valuable lead compounds for developing antitumor agents. Graphical abstract

P53 Directly Downregulates the Expression of CDC20 to Exert Anti-Tumor Activity in Mantle Cell Lymphoma

p53 Directly Downregulates the Expression of CDC20 to Exert Anti-Tumor Activity in Mantle Cell Lymphoma

Cirmtuzumab, an Anti-ROR1 Antibody, in Combination with Ibrutinib: Clinical Activity in Mantle Cell Lymphoma (MCL) or Chronic Lymphocytic Leukemia (CLL) from a Phase 1/2 Study

Cirmtuzumab, an Anti-ROR1 Antibody, in Combination with Ibrutinib: Clinical Activity in Mantle Cell Lymphoma (MCL) or Chronic Lymphocytic Leukemia (CLL) from a Phase 1/2 Study

Inhibition of cyclin-dependent kinase 9 synergistically enhances venetoclax activity in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is an aggressive and largely incurable subtype of non‐Hodgkin's lymphoma. Venetoclax has demonstrated efficacy in MCL patients with relapsed or refractory disease, however response is variable and less durable than CLL. This may be the result of co‐expression of other anti‐apoptotic proteins such as MCL‐1, which is associated with both intrinsic and acquired resistance to venetoclax in B‐cell malignancies. One strategy for neutralizing MCL‐1 and other short‐lived survival factors is to inhibit CDK9, which plays a key role in transcription. Here, we report the response of MCL cell lines and primary patient samples to the combination of venetoclax and novel CDK9 inhibitors. Primary samples represented de novo patients and relapsed disease, including relapse after ibrutinib failure. Despite the diverse responses to each single agent, possibly due to variable expression of the BCL‐2 family members, venetoclax plus CDK9 inhibitors synergistically induced apoptosis in MCL cells. The synergistic effect was also confirmed via venetoclax plus a direct MCL‐1 inhibitor. Murine xenograft studies demonstrated potent in vivo efficacy of venetoclax plus CDK9 inhibitor that was superior to each agent alone. Together, this study supports clinical investigation of this combination in MCL, including in patients who have progressed on ibrutinib.

Zanubrutinib monotherapy for patients with relapsed or refractory non-germinal center diffuse large B-cell lymphoma: Results from a phase II, single-arm, multicenter, study.

e20051 Background: The non-germinal center (non-GCB) subtype of diffuse large B-cell lymphoma (DLBCL) is associated with poor clinical outcomes. Inhibitors of Bruton’s tyrosine kinase (BTK) have established therapeutic activity in mantle cell lymphoma, chronic lymphocytic leukemia, and Waldenstrom macroglobulinemia and have shown modest activity in DLBCL. Zanubrutinib, a potent and selective BTK inhibitor, was evaluated in a phase 2 study in patients with relapsed or refractory (R/R) non-GCB DLBCL. Methods: The BGB-3111-207 study (NCT03145064) is a multicenter, single arm, phase 2 study in patients with R/R non-GCB DLBCL who were ineligible for intensive chemotherapy and bone marrow transplantation. Subjects received zanubrutinib 160 mg by mouth twice daily until disease progression or unacceptable toxicity. The primary endpoint was the overall response rate (ORR) using the Lugano criteria. Secondary endpoints included progression free survival (PFS) and duration of response (DOR). Overall survival (OS) was the exploratory endpoint. Results: Forty-one patients were enrolled at 11 sites in China between June 2017 and May 2018. Patients were 61% male, with a median age of 62 years. The median number of prior therapies was 2. International Prognostic Index risk was high-intermediate or high for 48.8% of patients, and 56.1% of patients had extranodal disease at study entry. As of the data cutoff date of May 24, 2019, four patients were continuing treatment and 37 patients had discontinued. With a median follow-up time of 6.8 months, the ORR was 29.3% and the complete response rate was 17.1%. The median DOR was 4.5 months, the median PFS was 2.8 months, and the median OS was 8.4 months. Adverse events (AEs) leading to treatment discontinuation were reported in four patients. Grade 3 or higher AEs were reported in 48.8% of patients. Major hemorrhage, atrial fibrillation and/or flutter, second primary malignancy, and tumor lysis syndrome were not observed. Conclusions: In this study zanubrutinib demonstrated modest antitumor activity in non-GCB DLBCL, similar to other BTK inhibitors. The safety profile was tolerable and consistent with previous reports of zanubrutinib treatment. Future studies of zanubrutinib in R/R non-GCB DLBCL will focus on the development of mechanism-based treatment combinations and biomarker-driven patient selection. Clinical trial information: NCT03145064 .

Drug Repurposing Screen Identifies Novel Classes of Drugs with Anticancer Activity in Mantle Cell Lymphoma.

Mantle Cell Lymphoma (MCL) is typically an aggressive and rare disease with poor prognosis, therefore new effective therapeutics are urgently needed. Drug repurposing for cancer treatment is becoming increasingly more attractive as an alternative approach to discover clinically approved drugs that demonstrate antineoplastic effect. The objective of this study was to screen an approved drug library and identify candidate compounds with an antineoplastic effect in MCL cells using High-Throughput Screening (HTS) technique. Using the HTS technique, nearly 3,800 clinically approved drugs and drug candidates were screened in Jeko and Mino MCL cell lines. We also demonstrated the selectivity window of the candidate compounds in six normal cell lines. Further validations were performed in caspase-3/7 apoptosis assay and three-dimensional (3D) multicellular aggregates model using Z138 cell line. We identified 98 compounds showing >50% inhibition in either MCL cell line screened, they were distributed across eight unique therapeutic categories and have different mechanisms of action (MOA). We selected alisertib, carfilzomib, pracinostat and YM155 for further validation based on their antiproliferative activity in two MCL cell lines, selectivity to normal cell lines, and drug developing stages in terms of clinical research. Alisertib and carfilzomib showed antiproliferative effect on MCL cell with EC50 = 6 nM and >100-fold selectivity to normal cell lines, especially for alisertib which demonstrated >1000-fold selectivity to 5 out of 6 normal cell lines. Pracinostat and YM155 had potency of 11 and 12 nM in MCL cell with >20-fold selectivity to normal cell lines. All four compounds had been tested in caspase-dependent apoptosis assay. We further validated and demonstrated their anti-MCL effect on cell proliferation and (3D) multicellular aggregates model using Z138 cell line. This is the first study to examine such a large library of clinically approved compounds for the identification of novel drug candidates for MCL treatment, the results could be rapidly translated into clinical practice in patients with MCL.

CC-122 Exhibits Greater Preclinical Activity in Mantle Cell Lymphoma Than Lenalidomide through a Combination of Direct Cell-Autonomous and Increased Antibody Dependent Cell-Mediated Cytotoxicity

Introduction: CC-122 and lenalidomide (len) bind the E3 ubiquitin ligase CUL4-RBX1-DDB1-CRBN (CRL4CRBN) resulting in degradation of the transcription factor Aiolos, leading to direct anti-lymphoma activity and T and NK cell activation. CC-122 degrades Aiolos at a faster rate and to a greater extent compared to len. Len is currently indicated for the treatment of relapsed/refractory (R/R) mantle cell lymphoma (MCL) in the United States and European Union. CC-122 is in development for DLBCL, FL and CLL in combination with the anti-CD20 monoclonal antibodies, rituximab (Rtx) and obinutuzumab (GA101). We compared the ability of len and CC-122 to effect cell autonomous activity and enhance antibody dependent cell-mediated cytotoxicity (ADCC) in pre-clinical models of MCL.Methods: Proliferation was measured by 3H labeling. Apoptosis was measured by Annexin V/ToPro-3 flow cytometry. ADCC was measured by a 4 hour co-incubation of Rtx or GA101 labeled cells with stimulated PBMC treated with DMSO, len or CC-122 for 3 days followed by apoptosis assay. Inducible shRNA targeting luciferase or Aiolos were activated with 10 ng/ml doxycycline for 7 days followed by apoptosis assay.Results: Lenalidomide treatment (10μΜ) for 5 days resulted in a 31% and 49% decrease in proliferation of two of the six MCL cell lines investigated, whereas CC-122 treatment (1.25μΜ) decreased proliferation in four MCL cell lines by 37-81%. There was no increase in Annexin V and ToPro-3 staining in MCL cells treated with len (0.1-10μΜ) for 7 days. By contrast, CC-122 treatment (0.1-10μΜ) reduced viability in four of six cell lines examined by 32-95%. Examination of the biochemical activity of each drug in Mino and Rec-1 cells demonstrated CC-122 (0.1-10μΜ) induced rapid Aiolos degradation at 6 hours (33-88% and 38-85%, respectively) compared to 10μΜ len (27% and 25%, respectively). In Jeko-1 cells, two distinct doxycycline inducible shRNA targeting Aiolos led to 56-97% decreased Aiolos protein expression. Furthermore, shRNA targeting Aiolos led to a 2- to 3-fold increase in apoptosis relative to shLuciferase. In ADCC assays of Z138 and Granta-519 coated with Rtx (1μg/ml) or GA101 (1μg/ml), CC-122 (10-100nM) was more potent than len (0.1-1μΜ). CC-122 treatment of PBMC increased Rtx labeled Z138 and Granta-519 apoptosis (39-59% and 36-48%, respectively) compared to len (24-35% and 33-40%, respectively), versus vehicle controls (13% and 13%, respectively). Additionally, CC-122 treatment increased GA101 mediated ADCC of Z138 and Granta-519 (60-76% and 59-67%, respectively) compared to len (49-61% and 55-63%, respectively), versus vehicle controls (35% and 41%, respectively).Conclusions: CC-122 treatment of MCL cells resulted in considerable cell autonomous activity in in vitro proliferation and viability assays compared to len. Specific targeting of Aiolos, a substrate which is rapidly degraded by CC-122, through inducible shRNA results in increased levels of apoptosis compared to shLuciferase controls. Additionally, the combination of CC-122 with either Rtx or GA101 in in vitro co-culture ADCC assays resulted in greater apoptosis than len combined with either antibody. The combination of both enhanced cell-autonomous activity and α-CD20 mediated ADCC provide a rational combination strategy for CC-122 development in R/R MCL. DisclosuresHagner:Celgene Corporation: Employment, Equity Ownership. Chiu:Celgene Corporation: Employment, Equity Ownership. Waldman:Celgene Corporation: Employment, Equity Ownership. Klippel:Celgene Corporation: Employment, Equity Ownership. Pourdehnad:Celgene Corporation: Employment, Equity Ownership. Gandhi:Celgene Corporation: Employment, Equity Ownership. Thakurta:Celgene: Employment, Equity Ownership.

The Pan Class-I PI3K Inhibitor Copanlisib Has Preclinical Activity in Mantle Cell Lymphoma, Marginal Zone Lymphoma and Chronic Lymphocytic Leukemia As Single Agent and in Combination with Other Targeted and Conventional Agents

Introduction. Copanlisib is a pan class-I PI3K inhibitor (i) with preferred activity towards PI3Kα and PI3Kδ that is currently in clinical development as single agent and in combination for patients with non-Hodgkin lymphomas. Here, we performed a screening of copanlisib as single agent and in combination with 15 other anti-cancer agents on a panel of 17 lymphoma cell lines derived from mantle cell lymphoma (MCL), marginal zone lymphoma (MZL) and chronic lymphocytic leukemia (CLL).Methods. Cell lines derived from MCL (Jeko1, Rec1, JVM2, Granta519, Maver1, Mino1, SP-49, SP-53, UPN1, Z138), MZL (Karpas1718, VL51, SSK41, ESKOL, HAIR-M, HC-1) and CLL (MEC1) were exposed to increasing doses of copanlisib alone and in combination with increasing doses of other compounds using the fixed ratio set-up. Tested compounds were approved as well as experimental inhibitors of key regulatory pathways: e.g. anti-CD20 monoclonal antibody rituximab, BTK-i ibrutinib, CDK-i roniciclib, DNA damage agent bendamustine, HDAC-i panobinostat, HDAC1/2-i romidepsin, immunomodulatory lenalidomide, JAK1/2-i ruxolitinib, MALT-i MI2, proteasome-i bortezomib. Synergy was assessed with Chou-Talalay combination index (CI): synergism (<0.9), additive (0.9-1.1), antagonism/no benefit (> 1.1). Gene expression profiling (GEP) was done using the Illumina-HumanHT-12 Expression-BeadChips and GSEA (FDR<0.25).Results. Copanlisib showed anti-tumor activity in the vast majority of cell lines with a median IC50 of 22nM (95%C.I.; 15-98) across all the cell lines, 36nM (6-175) in MZL, 22nM (95%C.I., 3-103) in MCL, 23nM in the CLL MEC1. Among all cell lines, the most active other compounds were bortezomib (IC50 5nM; 95%C.I., 5-7), romidepsin (34nM, 2-94), roniciclib (23nM, 18-29), panobinostat (161nM, 11-1263), MI2 (490nM; 224-1000) with remaining having median IC50s >500nM. Among these the only showing higher activity in one histotype was panobinostat, more active in MCL than MZL (IC50 17 vs 557nM, P 0.04). As pattern of activity across the cell lines, copanlisib was positively correlated with ibrutinib (R 0.58, P 0.001) and negatively with ruxolitinib (R -0.55, P 0.021).When copanlisib-containing combinations were tested in the 17 cell lines, different ones frequently appeared synergistic or additive: for example copanlisib plus MI2, 88% (15); plus ibrutinib, 82% (14); plus AKT-i or panobinostat, 76% (13); plus lenalidomide or BET-i, 71% (12); plus rituximab, 65% (11); plus romidepsin, 59% (10); plus roniciclib, 53% (9); plus bortezomib, 47% (8); plus bendamustine, 35% (6); plus ruxolitinib, 12% (2). For combinations with the most promising effect, baseline GEP identified gene-sets associated with different sensitivity to these combinations. High expression of genes involved in interferon signaling, oxidative phosphorylation, fatty acid metabolism, apoptosis, PI3K/AKT/mTOR and IL6/JAK/STAT signaling and low expression of genes involved in cell cycle were associated with synergism to copanlisib combinations with several compounds. Interestingly, largely the opposite was observed for the combination with others, with better synergy in cells with high expression of E2F/MYC targets and genes involved in cell cycle and low expression of transcripts involved in interferon PI3K/AKT/mTOR and IL6/JAK/STAT signaling.Conclusion. Copanlisib was active in cell lines derived from MCL, MZL and CLL. Combinations of copanlisib with a variety of additional anti-cancer compounds were synergistic and/or additive when combined in different cell lines. The combinations of the synergy profiles in the cell lines tested and the specific GEP features might predict lymphomas that could benefit from these regimens. DisclosuresJourdan:Bayer Pharma AG: Employment. Berthold:Bayer Pharma AG: Employment. Rossi:Gilead: Honoraria, Research Funding; Abbvie: Honoraria; Janseen: Honoraria. Lange:Bayer Pharma AG: Employment. Politz:Bayer Pharma AG: Employment.

Postibrutinib outcomes in patients with mantle cell lymphoma

AbstractDespite unprecedented clinical activity in mantle cell lymphoma (MCL), primary and acquired resistance to ibrutinib is common. The outcomes and ideal management of patients who experience ibrutinib failure are unclear. We performed a retrospective cohort study of all patients with MCL who experienced disease progression while receiving ibrutinib across 15 international sites. Medical records were evaluated for clinical characteristics, pathological and radiological data, and therapies used pre- and postibrutinib. A total of 114 subjects met eligibility criteria. The median number of prior therapies was 3 (range, 0-10). The Mantle Cell Lymphoma International Prognostic Index (MIPI) scores at the start of ibrutinib were low, intermediate, and high in 46%, 31%, and 23% of patients, respectively. Of patients with available data prior to ibrutinib and postibrutinib, 34 of 47 and 11 of 12 had a Ki67 >30%. The median time on ibrutinib was 4.7 months (range 0.7-43.6). The median overall survival (OS) following cessation of ibrutinib was 2.9 months (95% confidence interval [CI], 1.6-4.9). Of the 104 patients with data available, 73 underwent subsequent treatment an average of 0.3 months after stopping ibrutinib with a median OS of 5.8 months (95% CI, 3.7-10.4). Multivariate Cox regression analysis of MIPI before postibrutinib treatment, and subsequent treatment with bendamustine, cytarabine, or lenalidomide failed to reveal any association with OS. Poor clinical outcomes were noted in the majority of patients with primary or secondary ibrutinib resistance. We could not identify treatments that clearly improved outcomes. Future trials should focus on understanding the mechanisms of ibrutinib resistance and on treatment after ibrutinib.

Palbociclib (PD0332991)-a Selective and Potent Cyclin-Dependent Kinase Inhibitor: A Review of Pharmacodynamics and Clinical Development.

Palbociclib (PD0332991) is a newly developed drug that received breakthrough designation and recent US Food and Drug Administration approval in combination with endocrine therapy in the treatment of hormone receptor positive, ERBB2-negative (formerly HER2 or HER2/neu) breast cancer in the first-line metastatic setting. Herein we describe the preclinical and translational data and early- and late-phase clinical trials in which palbociclib has been investigated in a broad array of tumor types. We discuss the pharmacodynamics, pharmacokinetics, toxic effects, and clinical response rates. On March 1, 2015, we conducted a review of the literature describing the development of palbociclib. We used the PubMed search terms "PD0332991," "palbociclib," and "CDK4/6 inhibitor" to find all published articles of interest, without limitation as to publication date. Palbociclib is a potent and specific oral cyclin-dependent kinase (CDK) 4/6 inhibitor that has strong preclinical data to support its activity in retinoblastoma protein-expressing tumors. Phase 1 trials have demonstrated safety, and phase 2 trials have shown single-agent activity in mantle-cell lymphoma, breast cancer, liposarcoma, and teratoma with reversible neutropenia as the main toxic effect. Addition of palbociclib to endocrine therapy improves progression-free survival in endocrine therapy-naïve and endocrine therapy-resistant metastatic settings. Palbociclib is well tolerated and has therapeutic potential for multiple cancers, including breast cancer, where its efficacy has been demonstrated alone and in combination with endocrine therapy. Additional combinations of palbociclib with endocrine therapy, chemotherapy, and targeted therapy have potential in various tumors, and phase 3 trials are under way.

The Addition of the BTK Inhibitor Ibrutinib to Anti-CD19 Chimeric Antigen Receptor T Cells (CART19) Improves Engraftment and Antitumor Responses Against Mantle Cell Lymphoma

Introduction: The bruton tyrosine kinase (BTK) inhibitor ibrutinib demonstrates considerable activity in mantle cell lymphoma (MCL). However, approximately 30% of patients do not respond to this treatment and the therapy invariably leads to drug resistance with a median response of 17.5 months. Infusion of autologous T cells transduced with chimeric antigen receptors (CAR) against the B-cell specific CD19 antigen (CART19) leads to dramatic clinical responses in the majority of patients with acute lymphoblastic leukemia and the activity in B cell lymphoma is currently being evaluated in clinical trials. Bulky disease, as sometimes seen in MCL, may impair T cell infiltration. The features of ibrutinib that make it an interesting addition to CART19 include its efficacy in reducing tumor masses and its ability to mobilize neoplastic B cells into the peripheral blood, thereby potentially exposing them to the killing activity of CART19. Therefore, we sought to investigate the combination of the two novel targeted therapies, ibrutinib and CART19 in MCL.Results: In vitro studies with established MCL cell lines and with a novel cell line (MCL-RL) showed a range of responses to ibrutinib with an IC50 ranging from 10 nM to 10 µM; MCL-RL was the most sensitive cell line evaluated with an IC50 of 10nM, similar to primary MCL. Both ibrutinib-sensitive and ibrutinib-resistant cell lines strongly activated CART19 in an antigen-specific manner as detected by CD107a degranulation, cytokine production and CFSE proliferation assays. Importantly, in vitro assays with MCL cell lines co-cultured with increasing doses of CART19 (E:T= 2:1, 1:1, 0.5:1, 0.25:1) combined with increasing concentrations of ibrutinib (0, 10, 100, 1000 nM) demonstrated strong additive tumor killing (Figure 1). Notably, supra-therapeutic doses of Ibrutinib (>/=1 uM) impaired cytokine production and T cell proliferation in vitro. In order to test this combination in vivo we established a novel MCL model, injecting i.v. luciferase-positive MCL-RL cells into NSG mice. This resulted in 100% MCL engraftment in liver and spleen, with eventual dissemination into lymph nodes and bone marrow. Treatment with three different doses of CART19 (0.5, 1 and 2 million cells/mouse) led to a dose dependent anti-tumor effect. A similar dose response to CART19 was also observed in the ibrutinib-resistant Jeko-1 cell line. We also treated MCL-RL xenografts with different doses (0, 25 and 125 mg/Kg/day) of ibrutinib, with a median overall survival respectively of 70, 81 and 100 days (p<0.001). Importantly, a direct in vivo comparison of the highest ibrutinib dose (125 mg/kg) and CART19 showed a significantly improved tumor control for mice treated with CART19. However, treatment with either CART19 or ibrutinib as single agents invariably led to late relapse. Therefore we sought to treat MCL-RL xenografts with the combination of CART19 and ibrutinib and compare it to the single agent activity. The combination resulted in significant improvement in tumor control compared to mice treated with the single agents with 80% of mice achieving long-term disease-free survival ( p=0.007 at day 110, representative mice shown in Figure 2A). Intriguingly, we found that mice treated with ibrutinib had higher numbers of circulating CART19 cells (Figure 2B).Conclusions: Combining CART19 with ibrutinib represents a rational way to incorporate two of the most recent therapies in MCL. Our findings pave the way to a two-pronged therapeutic strategy in patients with MCL and other types of B-cell lymphoma. [Display omitted] [Display omitted] DisclosuresRuella:Novartis: Patents & Royalties, Research Funding. Kenderian:Novartis: Patents & Royalties, Research Funding. Maus:Novartis: Consultancy, Patents & Royalties, Research Funding. Milone:Novartis: Patents & Royalties, Research Funding. Lacey:Novartis: Patents & Royalties, Research Funding. Mato:Genentech: Consultancy; Pronai Pharmaceuticals: Research Funding; Celgene Corporation: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Gilead: Consultancy, Research Funding; TG Therapeutics: Research Funding; AbbVie: Consultancy, Research Funding; Janssen: Consultancy. Schuster:Genentech: Consultancy; Pharmacyclics: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Hoffman-LaRoche: Research Funding; Janssen: Research Funding; Gilead: Research Funding; Nordic Nanovector: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding. Kalos:Novartis: Patents & Royalties, Research Funding. June:Novartis: Research Funding; University of Pennsylvania: Patents & Royalties: financial interests due to intellectual property and patents in the field of cell and gene therapy. Conflicts of interest are managed in accordance with University of Pennsylvania policy and oversight. Gill:Novartis: Patents & Royalties, Research Funding. Wasik:Janseen and Novartis: Research Funding.

Ublituximab (TG-1101), a Novel Glycoengineered Anti-CD20 Monoclonal Antibody, in Combination with Ibrutinib Is Highly Active in Patients with Relapsed and/or Refractory Mantle Cell Lymphoma; Results of a Phase II Trial

Introduction: Ublituximab (UTX) is a novel, chimeric monoclonal antibody (mAb) which targets a unique epitope on the CD20 antigen and has been glycoengineered to enhance affinity for all variants of FcγRIIIa receptors, demonstrating greater ADCC than rituximab and ofatumumab. In patients (pts) with rel/ref CLL, the combination of UTX with ibrutinib was well-tolerated and highly active demonstrating an 88% ORR (95% ORR in high-risk CLL) with responses attained rapidly (median time to iwCLL response of 8 weeks). Ibrutinib has demonstrated single agent activity in Mantle Cell Lymphoma (MCL), achieving a 68% ORR (21% CR) in a single arm trial in relapsed or refractory patients (Wang et al, NEJM 2013). Herein we report on the first combination of ibrutinib with a glycoengineered anti-CD20 mAb, UTX, in patients with Mantle Cell Lymphoma (MCL).Methods: Eligible patients had rel/ref MCL with an ECOG PS < 3. Prior ibrutinib treatment was permitted. UTX (900 mg) was administered on Days 1, 8, and 15 in Cycle 1 followed by Day 1 of Cycles 2 - 6. Ibrutinib was started on Day 1 and continued daily at 560 mg. Following Cycle 6, patients came off study but could remain on ibrutinib. Primary endpoints were safety and ORR with an emphasis on early activity with response assessments by CT scan scheduled prior to cycles 3 and 6 only (criteria per Cheson 2007).Results: 15 patients were enrolled: 13 M/2 F, median age 71 yr (range 55-80), ECOG 0/1: 9/6, median prior Tx = 3 (range 1-8), 53% with ≥ 2 prior anti-CD20 therapies, 40% prior bortezomib. Gr 3/4 AE's occurring in at least 5% of patients and at least possibly related to UTX and/or ibrutinib included: neutropenia (13%), fatigue (7%), rash (7%) and atrial fibrillation (7%). Ibrutinib was dose reduced due to an AE in 1 patient (rash) and discontinued in 1 patient due to atrial fibrillation. No UTX dose reductions occurred. All 15 pts are evaluable for response with best response to treatment as follows: 87% (13/15) ORR with 33% (5/15) Complete Response. Three of the CR's occurred at week 8. Of the two patients not achieving an objective response, one patient was stable at first scan and came off treatment prior to second efficacy assessment (ibrutinib related A-Fib) and one patient progressed at first assessment. Responses generally improved from first to second assessment with median tumor reduction of 64% by week 8 and 82% by week 20.Conclusions: Ublituximab, a glycoengineered anti-CD20 mAb, in combination with ibrutinib is both well-tolerated and highly active in pts with rel/ref MCL. Response rate, depth of response, and time to response compare favorably to historical data with ibrutinib alone. A randomized phase 3 trial with ibrutinib +/- ublituximab is currently ongoing in high-risk CLL pts and future studies using this combination in MCL are being evaluated. DisclosuresKolibaba:Janssen: Research Funding; Novartis: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; Gilead: Consultancy, Honoraria, Research Funding; TG Therapeutics: Research Funding; GSK: Research Funding; Genentech: Research Funding; Cell Therapeutics: Research Funding; Celgene: Research Funding; Amgen: Research Funding; Amgen: Research Funding; Acerta: Research Funding. Burke:Gilead: Consultancy; Millenium/Takeda: Consultancy; Seattle Genetics, Inc.: Research Funding; Incyte: Consultancy; Janssen: Consultancy; TG Therapeutics: Other: Travel expenses. Farber:TG Therapeutics, Inc.: Research Funding. Fanning:Celgene and Millennium/Takeda: Speakers Bureau. Schreeder:TG Therapeutics, Inc: Research Funding. Boccia:Incyte Corporation: Honoraria. Sportelli:TG Therapeutics, Inc.: Employment, Equity Ownership. Miskin:TG Therapeutics, Inc.: Employment, Equity Ownership. Weiss:TG Therapeutics, Inc.: Employment, Equity Ownership. Sharman:Roche: Research Funding; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Research Funding; Calistoga: Honoraria; Janssen: Research Funding; TG Therapeutics, Inc.: Research Funding; Celgene Corporation: Consultancy, Research Funding.

Lenalidomide Exhibits Activity in Mantle Cell Lymphoma through Increased NK Cell Mediated Cytotoxicity

Introduction: Lenalidomide (Len) is indicated for the treatment of relapsed/refractory (R/R) Mantle Cell Lymphoma (MCL) in the United States and Switzerland. Len binds to the cullin 4 ring E3 ubiquitin ligase complex resulting in ubiquitination and subsequent proteasomal degradation of lymphoid transcription factors Aiolos and Ikaros leading to stimulation of immune cells, such as T-cells. Clinical trial CC-5013-MCL-002 (NCT00875667) is a randomized open-label phase II study in R/R MCL patients in which Len was given orally at 25 mg/day on days 1-21 of each 28-day cycle until progression (N=170). The control arm consisted of investigator choice of single-agent rituximab, gemcitabine, fludarabine, chlorambucil, or cytarabine (N=84). We explored the immune effects of Len treatment in MCL patients enrolled in CC-5013-MCL-002 and further investigated our findings in in vitro MCL co-culture models. Methods: Peripheral blood samples for exploratory analysis were collected at Cycle 1 Day 1 (C1D1, pre-treatment), Cycle 1 Day 4 (C1D4), Cycle 2 Day 15 (C2D15) and at treatment discontinuation. Flow cytometric profiling of T, B and natural killer (NK) cell subsets was performed and differences were analyzed for correlation with clinical outcomes (response rate and progression free survival [PFS]). Cell dependent cytotoxicity was measured in 1) anti-CD3 stimulated peripheral blood mononuclear cells (PBMC) treated with vehicle or 1-10000 nM Len for 3 days and incubated with target tumor cells for an additional 4 hours followed by an apoptosis assay as measured by Annexin V/ToPro-3 flow cytometry and 2) negatively selected CD56+ NK cells stimulated with IL-2 and treated with Len (1 nM to 10 μM) for 18 hrs and incubated with target tumor cells for an additional 4 hours followed by apoptosis assay. Results: At baseline, no significant differences were observed in the absolute levels of immune subsets when comparing non-responders (NR) and responders (R) in either Len (NR=11, R=23) or control (NR=4, R=5) arms. However, in the Len arm, significantly elevated (adj. p The mechanism whereby NK cell modulation contributes to clinical benefit demonstrated by Len in patients was further explored in in vitro co-culture systems with MCL cell lines. Len treated PBMC co-cultured with Jeko-1, Granta-519, and Mino MCL cell lines resulted in 38-47.5% more apoptosis compared to DMSO (p≤0.001). We examined the effect of Len on Aiolos and Ikaros protein expression in CD56+ NK and CD3+ T cells within anti-CD3 antibody stimulated PBMCs treated with DMSO or various concentrations of Len (1 nM to 10 μM) for 72 hours. Degradation of both Aiolos (40%) and Ikaros (95%) was observed after drug treatment in CD56+ NK cells. Aiolos and Ikaros levels were also monitored in CD3+ T cells and showed decreased levels after Len treatment, consistent with previous reports (Gandhi, 2014; Kronke, 2014). Furthermore, purified CD56+ NK cell mediated cytotoxicity produced a similar pro-apoptotic effect as the PBMC assay in all MCL cell lines versus DMSO (p≤0.01). Supernatants from co-cultures of NK cells with MCL cell lines showed significantly elevated granzyme B levels as compared to DMSO controls (p≤0.0001), suggesting that the apoptotic effects observed are induced by granzyme B. Conclusions: Lenalidomide is an immune modulating agent and NK cell modulation in particular may play a role in its clinical activity in MCL. A significant increase in proportions of NK cell subsets (vs total lymphocytes) at C1D4 versus baseline was observed and is a potential response indicator of favorable clinical outcome in R/R MCL patients treated with Len. In vitro, Len enhances cell mediated cytotoxicity of MCL cell lines in two co-culture model systems. Understanding NK cell mediated mechanism(s) has potential to enhance guiding patient selection strategies and rational combination therapies of lenalidomide in MCL. Disclosures Hagner:Celgene: Employment, Equity Ownership. Chiu:Celgene: Employment, Equity Ownership. Ortiz-Estevez:Celgene: Employment, Equity Ownership. Biyukov:Celgene: Employment, Equity Ownership. Brachman:Celgene: Employment, Equity Ownership. Trneny:Celgene: Consultancy, Honoraria, Other: Travel, accommodations, expenses, Research Funding. Morschhauser:Genentech Inc./Roche: Other: Advisory boards. Stilgenbauer:AbbVie, Amgen, Boehringer-Ingelheim, Celgene, Genentech, Genzyme, Gilead, GSK, Janssen, Mundipharma, Novartis, Pharmacyclics, Roche: Consultancy, Honoraria, Research Funding. Milpied:Celgene: Honoraria, Research Funding. Musto:Sandoz: Consultancy; Celgene: Honoraria; Roche: Honoraria; Sanofi: Consultancy; Genzyme: Consultancy; Novartis: Honoraria; Janssen: Honoraria; Mundipharma: Honoraria. Martinelli:AMGEN: Consultancy; Ariad: Consultancy; Pfizer: Consultancy; ROCHE: Consultancy; BMS: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; MSD: Consultancy. Heise:Celgene: Employment, Equity Ownership. Daniel:Celgene: Employment, Equity Ownership. Chopra:Celgene: Employment, Equity Ownership. Carmichael:Celgene: Employment, Equity Ownership. Trotter:Celgene Corporation: Employment. Gandhi:Celgene: Employment, Equity Ownership. Thakurta:Celgene Corporation: Employment, Equity Ownership.