Efficacy Of Entinostat Research Articles

A phase I/II study to evaluate the safety, pharmacodynamics, and efficacy of entinostat in combination with atezolizumab and bevacizumab in patients with renal cell carcinoma.

4526 Background: Immunosuppressive factors such as regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) limit the efficacy of immunotherapies. We have previously reported that histone deacetylase (HDAC) inhibitors have antitumor effects in combination with PD-1 inhibition by inhibiting the function of Tregs and MDSCs in preclinical models. We hypothesized that HDAC inhibition may enhance or resensitize patients (pts) with renal cell carcinoma (RCC) to immunotherapy. Thus, we conducted a Phase I/II clinical study with the HDAC inhibitor entinostat in combination with the immune check point inhibitor atezolizumab and the VEGF inhibitor bevacizumab in RCC pts, either treatment naïve or previously treated with immune checkpoint inhibitors. Methods: The primary objective was to evaluate the safety, tolerability, and efficacy of this combination strategy in a Phase I/II clinical trial. This clinical study was composed of a Dose Finding Phase (Phase I) and a two-stage Phase (Phase II) portion. Due to unforeseen circumstances, enrollment was halted during Stage I of the Phase II portion. In the Phase I dose finding cohorts, according to the 3+3 standard design, pts received oral entinostat at 1 mg (dose level or dl1), 3 mg (dl 2), or 5 mg (dl 3) every 7 days, continuously, with atezolizumab at a dose of 1,200 mg/kg mg IV every three weeks in combination with bevacizumab at a dose of 15 mg/kg IV every 3 weeks. Phase II patients were split into two distinct cohorts: Cohort A (no prior treatments with PD-1 or PD-L1 inhibitors) and Cohort B (at least one prior treatment with a PD-1 or PD-L1 inhibitor for metastatic disease). Pts treated at dl3 were included in the Phase II efficacy analyses. Results: 31 pts (18 and 13 pts during Phase I and II, respectively) were enrolled. Phase I was completed with the following DLTs: hypertension (3) in dl1, encephalopathy and hyponatremia (dl2), pneumonitis and pruritis (dl3). Dl3 was established as the recommended phase II dose. The most common treatment-related toxicities were thrombocytopenia, hypophosphatemia, proteinuria, diarrhea, fatigue, and neutropenia. A total of 21 grade≥3 events were observed. Nine pts achieved a partial response in Cohort A and one patient in Cohort B with an ORR 60% (CI 32.3-83.7) and 33.3% (28.2-56.4), respectively. According to Simon’s optimal two-stage design, the ORR met the Stage I primary objective. The median PFS was 13.7 months (CI 8.7-21.3) in Cohort A and 9.8 months (CI 1.3-NE) in Cohort B. We have collected blood samples to conduct several correlative studies on peripheral blood mononuclear cells. Conclusions: The preliminary results from this study suggest that the combination of entinostat and atezolizumab plus bevacizumab is relatively well tolerated and may be active in pts with ccRCC. Clinical trial information: NCT03024437 .

A phase II study to evaluate the safety, pharmacodynamics and efficacy of entinostat in combination with nivolumab plus ipilimumab in patients with renal cell carcinoma previously treated with nivolumab plus ipilimumab or nivolumab alone.

668 Background: Immunosuppressive factors such as regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) limit the efficacy of immunotherapies. We have previously reported that histone deacetylase (HDAC) inhibitors have antitumor effects in combination with PD-1 inhibition by inhibiting the function of Tregs and MDSCs in preclinical models. We hypothesized that HDAC inhibition may resensitize patients (pts) with renal cell carcinoma (RCC) to immunotherapy. Thus, we opened a Phase II clinical study with the HDAC inhibitor entinostat and the immune check point inhibitors nivolumab (nivo) and ipilimumab (ipi) in clear cell RCC pts previously treated with nivo + ipi or nivo alone. Methods: The primary objective was to evaluate the safety, tolerability, and efficacy of this combination strategy in a dose de-escalation, two stage, phase II clinical trial with a safety lead-in. Due to a funder decision, enrollment was halted after completion of accrual to the safety lead in group. Pts received oral entinostat at a dose of 5 mg (dose level 1) or 3 mg (dose level 2) every 7 days, continuously, with nivo at a dose of 3 mg/kg mg IV every three weeks in combination with ipi at a dose of 1 mg/kg every 3 weeks X 4 doses. Then, nivo 480 mg was continued every 4 weeks. Results: A total of 12 pts with prior nivo+ipi or nivo treatments was enrolled. Dose level 1 (5 pts enrolled) was completed with the following DLTs: thrombocytopenia, nausea and vomiting, pneumonitis. Seven pts were enrolled on dose level 2 which was established as the recommended phase II dose. The most common treatment-related toxicities were fatigue, hypophosphatemia, neutropenia and thrombocytopenia. All were transient. Most of the pts had 2 or more prior treatments. Four pts achieved a partial response, with 3 out 4 pts previously treated with nivo alone (ORR 33%; 95% CI 9.9-65.1). The median PFS was 11.1 months (CI 1.3-26.4). We collected blood samples to conduct several correlative studies including flow cytometry and gene expression analysis on peripheral blood mononuclear cells. Conclusions: The preliminary results from this study suggest that the combination of entinostat and nivo+ ipi is relatively well tolerated and may be active in pts with RCC. Clinical trial information: NCT03552380 .

Abstract 239: Assessment of immunotherapeutic efficacy of entinostat by using the 3d-explore ex vivo platform utilizing tumoroids of fresh patient tumor samples with intact tumor microenvironment

Abstract Background: Entinostat, a selective histone deacetylase 1/3 inhibitor has been shown to promote a robust anti-tumor response and increased neoantigen expression and antigen-specific T cell activation in preclinical tumor models. Entinostat plays a role in neutralizing myeloid derived suppressor cells (MDSC) to improve anti-tumor immune response. Entinostat is currently being tested in later-stage clinical trials in various types of cancer. Using a novel 3D ex-vivo platform with fresh patient tumor samples we assessed the therapeutic efficacy of Entinostat with intact stromal components and tumor immune microenvironment. Methods: All tumor samples were obtained with patient consent and relevant IRB approval. Unpropagated 3D tumoroids with intact TME measuring 150 µm in size were prepared from fresh tumor samples from renal cell carcinoma (RCC) patients using a proprietary technology developed at Nilogen Oncosystems. Tumoroids prepared from each patient’s tumor sample were pooled to represent the tumor heterogeneity and treated ex vivo with Entinostat for 48h to detect treatment-mediated changes in tumor immune cell composition including lymphoid and myeloid markers and their activation status. Results: Tumoroids treated with Entinostat increased NK, NKT, CD4 and CD8+T cells compared to untreated control. Ex vivo treatment with Entinostat led to an increase in CD69 and Granzyme B expression in tumor resident CD4+ T cells. Immune checkpoint receptors, 41BB and PD-1 expression was increased in CD8+T cells followed by Entinostat treatment. Decreased monocytic MDSC was seen in Entinostat treated tumoroids compared to untreated control and this was associated with decreased GM-CSF, IL-4, IL-6 cytokine levels and increased IFN-γ and IL-2, quantified by multiplex cytokine assay. Interestingly, the tumor cell killing study revealed a higher percentage of death in early stage MDSC (eMDSC) indicating a direct effect of Entinostat on MDSC survival. Conclusions: These results demonstrate that Entinostat treatment leads to a broad range of immune cell activation and MDSC inhibition in RCC. These data provide a mechanistic rationale utilizing our 3D tumoroid platform for discovery of potential biomarkers of drug sensitivity and to identify novel immunotherapeutic approaches. Clinical applications of 3D-EXplore may help to identify RCC patients who may likely benefit from Entinostat treatment. Citation Format: Krithika Nandakumar Kodumudi, Brittany Bunch, Jared Ehrhart, Matt Weitzman, Olivia MacIntosh, Kelly Sussman, Soner Altiok. Assessment of immunotherapeutic efficacy of entinostat by using the 3d-explore ex vivo platform utilizing tumoroids of fresh patient tumor samples with intact tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 239.

Phase I study of entinostat in combination with enzalutamide for treatment of patients with castration-resistant prostate cancer.

96 Background: Entinostat (SNDX-275, MS-275) is an oral histone deacetylase (HDAC) inhibitor with selectivity towards class I and IV HDACs. Entinostat inhibits prostate cancer (PCa) growth and suppresses Treg cell function in vitro and in vivo. The primary objective of this study was to determine the safe dose of Entinostat in combination with Enzalutamide in prostate cancer patients (PCa). Methods: Phase I, 2 cohorts "3+3", dose-escalation study to explore the safety and preliminary efficacy of Entinostat in combination with Enzalutamide in castration-resistant PCa (CRPC). The planned dose level of Entinostat was 3 and 5 mg orally per week. CRPC Patients progressed on Enzalutamide or eligible for Enzalutamide, able to tolerate 160 mg daily dose (in the initial run-in phase if Enzalutamide naïve), ECOG 0-1, and acceptable organ functions were enrolled in the study. The safety profile of the combination therapy, PSA, pharmacokinetics of Enzalutamide post-Entinostat administration, and peripheral T cell subtype (including Treg), mononuclear cell (PBMC) histone 3 acetylation were analyzed. Results: Total 6 mCRPC patients were enrolled. There was no dose limiting toxicity related to Entinostat in these patients. No obvious increased fatigue related to Entinostat. Toxicities possibly or probably related to Entinostat or the combination therapy included G3 anemia 1/6 (17%), G2 WBC decrease 1/6 (17%), All other toxicities were grade 1 only (Nausea 2/6, anorexia 1/6, emesis 1/6, constipation 1/6, headache 1/6, platelet count decrease 1/6, hypokalemia 1/6, hypoalbuminemia 1/6, hypermagnesemia 1/6). The median duration of treatment with Entinostat was 18 weeks. For patients already progressed on Enzalutamide there was no PSA response after Entinostat was added. Entinostat did not affect the steady plasma concentration of Enzalutamide. Increased PBMC H3 acetylation was observed (up to 3.6 fold from baseline) in the tested samples. No evident T cell subtype, including Treg, changes from these sample analysis. Phase II part of the trial was terminated because of sponsor withdrawal. Conclusions: Entinostat at the selected dose levels in combination with standard dose of enzalutamide showed promising safety profile in this small phase I study. Clinical trial information: NCT03829930.

Abstract 1379: Entinostat induces PARPi sensitivity across multiple ovarian cancer models

Abstract Introduction: Ovarian cancer is a rare, but fatal disease and a leading cause of gynecologic cancer death, in the United States. Poly ADP ribose polymerase inhibitors (PARPi) are promising drugs, most effective in patients with tumors deficient in homologous recombination (HR) genes, mainly BRCA1/2. Our group has published that histone deacetylase inhibitors (HDACi) sensitized HR proficient BRCA wild-type ovarian cancer cells to PARPi, however the mechanism still remains elusive and the efficacy needed to be tested across multiple models. We recently tested Entinostat with and without Olaparib in three different ovarian cancer models, including human/mouse established cell lines, PDX derived primary cell lines and immune-competent/immune-compromised xenograft as well as PDX-derived preclinical mouse models. Objective: To delineate the efficacy of Entinostat to sensitize ovarian tumors to Olaparib across multiple models and determine the underlying mechanism. Methods: HR proficient BRCA wild-type ID8/SKOV3 and PDX derived primary cell lines were treated with Entinostat and Olaparib, alone or in combination and analyzed for cell proliferation. DNA damage was studied using Comet assay. Expression of cell proliferation, DNA damage and repair protein were studied using Western blot analysis and immunofluorescence. Further, ID8-treated immune-competent mouse models, SKOV3-treated immune-compromised mouse model and HGSOC patient derived PDX mouse model generated in our lab were treated with vehicle, Entinostat, Olaparib, or the combination. The mice were monitored for toxicity and body weight measured twice weekly, till tissue harvest or survival. Results: Cell proliferation was significantly decreased (p&lt0.05) in Entinostat-Olaparib combination treated groups in all cell lines tested. Comet assay showed significantly longer comet tail length in combination treated cells compared to control (p&lt0.05). Western blot and Immunofluorescence showed that combination treatment significantly decreased BRCA1, PCNA, RAD51 and increased cleaved PARP, ΓH2AX (p&lt0.05). Further, SKOV3- xenograft mouse model showed decreased tumor burden ((p&lt0.07), ID8-xenograft mouse tumors showed decreased Ki67 (p&lt0.05) and HGSOC derived PDX model showed longer survival when treated with Entinostat-Olaparib combination therapy. Conclusion: Entinostat in combination with Olaparib decreased cell proliferation, increased DNA damage, induced HR deficiency in vitro, reduced tumor burden, decreased Ki67 in xenograft mouse model, and improved survival of HGSOC derived PDX mice, thereby potentially sensitizing homologous recombination proficient ovarian cancer to PARPi across multiple models. Citation Format: Vijayalaxmi G. Gupta, Shariska Petersen, Jeff Hirst, Katherine Roby, Harsh Pathak, Meghan Kusch, Andrew Wilson, Andrew Godwin, Dineo Khabele. Entinostat induces PARPi sensitivity across multiple ovarian cancer models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1379.

Abstract P3-11-06: A phase 1 study of KHK2375 (entinostat) as monotherapy and in combination with exemestane in Japanese patients with hormone receptor-positive, HER2-negative, advanced or recurrent breast cancer

Abstract Background: Patients (pts) with hormone receptor-positive (HR+) and non-life threatening advanced or metastatic breast cancer (BC) are usually treated with sequential endocrine therapies. Endocrine therapies are continued until tumor cells acquire resistance to them, following which pts are switched to cytotoxic chemotherapy. Entinostat (ENT) is an oral inhibitor of class I histone deacetylases (HDACs) and is expected to be used for endocrine therapy-resistant pts. The efficacy of ENT in combination with an aromatase inhibitor (AI) for HR+ BC was demonstrated in a previous randomized phase 2 study. Because of the lack of data on safety and pharmacokinetics (PK) in Japanese HR+ BC pts, we performed this dose escalation phase 1 study to investigate the safety of ENT monotherapy and combination therapy with exemestane (EXE) in postmenopausal women with advanced or recurrent HR+ BC. Secondary objectives were to assess PK and efficacy. Methods: This study was based on a 3+3 dose escalation design. Postmenopausal women with advanced or recurrent HR+ HER2- BC previously treated with nonsteroidal AIs and with ECOG PS 0-1 were enrolled. The dose limiting toxicities (DLT) of ENT monotherapy (3 mg/qw, 5 mg/qw, or 10 mg/q2w) in Cohort 1-3 and those of ENT (5 mg/qw or 3 mg/qw) in combination with EXE 25 mg/qd in Cohort 4-5 were assessed for 7 and 28 days, respectively. Pts continued ENT (3 mg or 5 mg) in combination with EXE even after the DLT observation period until disease progression or discontinuation for other reasons. Adverse events (AEs) were graded per NCI-CTCAE version 4.03. Tumor response was evaluated by RECIST version 1.1 every 8 weeks. ENT concentration was measured intensively. Samples of peripheral blood mononuclear cells (PBMC) were collected to measure protein lysine hyperacetylation and for immune subset analysis. Optional tumor biopsies for biomarker assessment were collected before and during treatment. Results: Twelve pts were enrolled and three each were assigned to Cohort 1-4 between Nov 2015 and Sept 2016. Neither DLT nor grade 3-5 AE occurred. As no DLT occurred in Cohort 4, Cohort 5 was omitted as originally planned. The drug-related AEs observed in ≥2 pts during the DLT observation period were grade 1-2 hypophosphatemia (1 pt each in Cohort 2, 3, and 4), grade 1 nausea (1 pt in Cohort 3 and 2 pts in Cohort 4), and grade 1-2 platelet count decreased (2 pts in Cohort 4). AUC0-168 increased in a dose proportional manner. As of May 2017, 4 pts continue to receive study treatment, including one treated for more than 18 months. Biomarker data including protein lysine hyperacetylation and immune subset in PBMC and results of paired biopsy samples will be reported. Conclusions: This study showed the tolerability of the combination therapy of ENT 5 mg with EXE 25 mg in Japanese pts. There were no new safety concerns as compared to those reported previously. Following this result, a randomized phase 2 study for Japanese pts is planned. Clinical trial information : NCT02623751. Citation Format: Shimomura A, Masuda N, Tamura K, Yasojima H, Sawaki M, Nishimura Y, Saji S, Iwata H. A phase 1 study of KHK2375 (entinostat) as monotherapy and in combination with exemestane in Japanese patients with hormone receptor-positive, HER2-negative, advanced or recurrent breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-11-06.

Abstract P5-03-05: Genomic analysis and efficacy of entinostat in basal-like and HER2-overexpressing models

Abstract Background. The histone deacetylase inhibitor Entinostat has been under development for patients with metastatic estrogen receptor-positive breast cancer, and its use in Basal-like and HER2-overexpressing breast cancer has been limited. Here we provide results of a study using cell-lines and genetically engineered mouse (GEM) models of breast cancer to examine the effects of Entinostat and combination therapies on multiple in vitro and in vivo models. Methods. Breast cancer cell lines SKBR3, BT474 and MCF-7 were treated with or without Entinostat at their IC50 doses and their gene expression profiles determined. Two breast cancer GEM models (MMTV-neu and C3-Tag) were used to test the efficacy of Entinostat alone, or in combination with cyclophosphamide, or a murine version of an anti-mouse PD1 immune checkpoint inhibitor. Results: Entinostat was an effective in vitro drug with IC50 ranging from 700 to 1500 nM. Supervised analysis of gene expression data coming from treated cell lines showed induction of multiple major histocompatibility complex (MHC) class I/II genes on 6p21. In addition, several MHC genes were also upregulated in C3-Tag treated by Entinostat; because of these findings, the GEM models are currently being treated with the combination of Entinostat and the anti-mouse PD-1 inhibitor. In vivo, GEM tumors treated only with Entinostat were observed to have high objective response rates of 88% and 33% in MMTV-Neu and C3-Tag, respectively. The combination with cyclophosphamide provided significant improvements in the C3-Tag mice over either agent alone, with 11 of 17 mice achieving a CR or PR, and an extension of overall survival (98 days vs 33 days); Entinostat (42d, p=0.002) and Cytoxan (47d, p=0.001). Conclusions. Entinostat showed anti-tumor activity in vitro and in vivo, and was synergistic with cyclophosphamide in the Basal-like C3-Tag mouse model. The upregulation of MHC genes induced by Entinostat at RNA level suggested the interaction with immune response, which is currently under study and will be presented. Citation Format: Tanioka M, Usary J, Darr DB, Harrell CJ, Perou CM. Genomic analysis and efficacy of entinostat in basal-like and HER2-overexpressing models. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-03-05.

Abstract 5439: Characterization of the class 1 histone deacetylase inhibitor entinostat in EGFRi acquired resistance models and in combination with cetuximab in NSCLC

Abstract Background: Entinostat is a novel oral benzamide HDACi characterized by its selectivity for class 1 HDACs as well as a unique pharmacokinetic (PK) and pharmacodynamic (PD) profile. Previous results have demonstrated the ability of entinostat to synergize in vitro and in vivo with the small molecule EGFR inhibitors, gefitinib and erlotinib as well as EGFR directed antibody, cetuximab to inhibit growth of EGFRi resistant NSCLC cells. The mechanism for the combined efficacy may involve a) targeting of EGFR gene and protein expression b) down-regulation of EGFR-mediated signal transduction pathway c) alteration of the tumor phenotype to re-sensitize cancer cells to EGFRi. Methods: The growth inhibitory effect of the combination of erlotinib and entinostat in H1975 and H1933 cells was determined using a 5-day 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In vivo efficacy of entinostat was tested in athymic nude mice bearing NSCLC xenografts, A549 and H460. Combined treatment of entinostat with cetuximab was studied in H460 xenografts Results: We have extended our previous work examining the effect of entinostat on EGFRi resistance through testing of entinostat combined with erlotinib in cell line models of acquired resistance and evaluating the combination of entinostat with cetuximab in vivo in a xenograft model. Our results demonstrate that the combination of entinostat and erlotinib has enhanced activity in H1975 NSCLC cells which harbor the EGFRi T790M mutation. In addition the combination is more effective in H1933 NSCLC cells which have a met amplification. To further characterize the potential mechanism of action by which entinostat sensitizes NSCLC cells to EGFRi we have also tested entinostat in vivo in A549 and H460 xenograft models. Entinostat exhibits a dose response inhibition of tumor growth in both models and analysis of molecular markers is ongoing. In our previous experiments examining impact of entinostat on EGFRi resistance we reported on the combined efficacy of entinostat and cetuximab in the A549 NSCLC xenograft model. We have followed up on those initial findings through testing in a second xenograft model (H460) and will report those results. Conclusions: Entinostat enhances the effect of EGFR inhibitors in models of acquired EGFR resistance. The results from these experiments support the rationale of combining HDACi and EGFRi (small molecules as well as antibodies) in clinical studies in NSCLC. Ongoing clinical trials testing these hypothesis include ENCORE-401, a randomized, placebo controlled phase 2 study of erlotinib +/− entinostat in NSCLC patients and a pilot study, ENCORE-403 which was initiated to test the effect of entinostat on resistance to the EGFRi erlotinib in NSCLC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5439.