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Purpose: Checkpoint kinase 1 (Chk1) plays a critical role in the activation of mitotic spindle checkpoint and DNA damage checkpoint. We examined the preclinical use of the Chk1 inhibitor PF-00477736 as a docetaxel-sensitizing agent. Specifically, we investigated the correlation between PF-00477736–mediated modulation of biomarkers and the sensitization of docetaxel efficacy.Experimental Design:In vitro and in vivo studies using COLO205 and other cell lines were done to assess PF-00477736–induced enhancement of docetaxel efficacy and effects on associated biomarkers.Results: PF-00477736 significantly enhanced the docetaxel-induced efficacy in tumor cells and xenografts. Docetaxel induced dose- and time-dependent increase in the levels of phosphorylated Chk1 (Ser345), phosphorylated histone H3 (Ser10), and γH2AX foci and promoted the cytoplasmic localization of phosphorylated Cdc25C (Ser216). PF-00477736 cotreatment suppressed docetaxel-induced changes in phosphorylated histone H3 and cytoplasmic phosphorylated Cdc25C (Ser216) levels and concurrently sensitized the docetaxel-induced apoptosis. Docetaxel alone or in combination with PF-00477736 induced significant antiproliferative activity in xenografts, shown via [18F]FLT-PET imaging. However, changes in [18F]FLT uptake did not reflect the potentiation of docetaxel efficacy. In contrast, bioluminescence imaging showed that PF-00477736 sensitized docetaxel-induced suppression of tumor survival.Conclusions: Docetaxel triggers mitotic spindle checkpoint activation at low concentrations and activates both the DNA damage checkpoint and the spindle checkpoint at high concentrations. In combination with docetaxel, PF-00477736 abrogates the mitotic checkpoint, as well as the DNA damage checkpoint, and results in sensitization to docetaxel. Chk1 inhibitor PF-00477736 offers a therapeutic potential for the enhancement of taxane therapy.

Supplementary Data from PF-00477736 Mediates Checkpoint Kinase 1 Signaling Pathway and Potentiates Docetaxel-Induced Efficacy in Xenografts

The chemokine receptor CXCR4 is highly expressed and associated with poor prognosis in multiple malignancies. Upon engagement by its ligand, CXCL12, CXCR4 triggers intracellular signaling pathways that control trafficking of cells to tissues where the ligand is expressed, such as the bone marrow (BM). In hematologic cancers, CXCR4-driven homing of malignant cells to the BM protective niche is a key mechanism driving disease and therapy resistance. We developed a humanized CXCR4 immunoglobulin G1 (IgG1) antibody (Ab), PF-06747143, which binds to CXCR4 and inhibits CXCL12-mediated signaling pathways, as well as cell migration. In in vivo preclinical studies, PF-06747143 monotherapy rapidly and transiently mobilized cells from the BM into the peripheral blood. In addition, PF-06747143 effectively induced tumor cell death via its Fc constant region-mediated effector function. This Fc-mediated cell killing mechanism not only enhanced antitumor efficacy, but also played a role in reducing the duration of cell mobilization, when compared with an IgG4 version of the Ab, which does not have Fc-effector function. PF-06747143 treatment showed strong antitumor effect in multiple hematologic tumor models including non-Hodgkin lymphoma (NHL), acute myeloid leukemia (AML), and multiple myeloma (MM). Importantly, PF-06747143 synergized with standard-of-care agents in a chemoresistant AML patient-derived xenograft model and in an MM model. These findings suggest that PF-06747143 is a potential best-in-class anti-CXCR4 antagonist for the treatment of hematologic malignancies, including in the resistant setting. PF-06747143 is currently in phase 1 clinical trial evaluation (registered at www.clinicaltrials.gov as #NCT02954653).

312 Background: Sitra is a spectrum-selective receptor tyrosine kinase inhibitor (TKI) that targets TAM receptors (TYRO3, AXL, MERTK), VEGFR2, c-Kit, and MET. These receptors regulate several immune suppressive cell types in the tumor microenvironment, including M2-polarized macrophages, MDSCs, and T regulatory cells, which are implicated in resistance to checkpoint inhibitors. ccRCC is characterized by upregulation of VEGF and overexpression of MET and AXL. Sitra may combine effectively with immune checkpoint inhibition to augment antitumor activity in ccRCC. About 39% of patients with accRCC who receive surgery with curative intent relapse representing an unmet need in this setting. Together these data support the evaluation of neoadjuvant sitra with nivo in accRCC. Methods: This phase II study (NCT03680521) evaluated sitra and nivo in pts with locally- advanced ccRCC who were candidates for curative nephrectomy. Single-agent sitra (120 mg) was administered daily (QD) for 2 weeks, with nivo (240 mg intravenously Q2W) added to sitra for 4-6 weeks. A plan for potential dose de-escalation was implemented using a modified toxicity probability interval method with a maximum toxicity of 20% at the tolerated dose. Pts underwent pathology/tissue evaluation at 3 timepoints: biopsy prior to treatment, biopsy prior to the addition of nivo, and nephrectomy specimen evaluation at time of nephrectomy. The primary endpoint was objective response (RECIST 1.1); secondary endpoints included safety, PK, and correlative immune effects (selected protein and gene expression and immune cell populations). Results: A total of 20 pts were evaluated for safety (95% had T3 or higher stage tumors, 65% with baseline hypertension). Dose-limiting toxicities (DLTs) led to a dose de-escalation, resulting in 7 pts treated at 120 mg QD sitra and 13 pts treated at 80 mg QD. DLTs included grade 3 (Gr3) hypertension (n=6); deep vein thrombosis and pulmonary embolism (Gr3) were observed in 1 additional pt. Median duration of sitra treatment was 6.3 weeks at the 80 mg dose and 7.1 weeks at the 120 mg dose. With a median follow-up of 9.4 months after initiation of systemic therapy, no pts have relapsed. In 17 pts evaluable for efficacy, the investigator-assessed confirmed ORR was 11.8%, including 2 PRs (33.3% ORR in pts who received 120 mg sitra). No pts experienced progressive disease while on therapy. Median DFS was not reached. There was 1 delayed surgery due to nivo-related thyroiditis that resolved. Reported TRAEs: Gr1/Gr2 in 55% of pts (dysphonia 50%, fatigue 45%, diarrhea 40%, hypertension 30%, increased ALT 30%), Gr3 in 45% of pts (hypertension 30%). There were no Gr4/Gr5 TRAEs. Correlative blood and tissue analyses will be presented. Conclusions: The combination of sitra and nivo is clinically active with a manageable safety profile as a neoadjuvant therapy for accRCC. Clinical trial information: NCT03680521 .

10052 Background: Mocetinostat is a class I/IV HDAC inhibitor with HDAC1/2/3/11 activity. Preclinical murine data suggest that HDAC inhibition has immune activity and may augment the clinical benefit of checkpoint inhibition. Several trials are assessing the effects of adding HDAC inhibition to PD-1 blockade. Methods: Patients with therapy-naive metastatic melanoma were treated in a pilot phase Ib trial with nivolumab at 3 mg/kg/ipilimumab at 1 mg/kg every three weeks four times and a starting dose of mocetinostat at 70 mg orally three times a week in a 12-week induction cycle followed by 12-week maintenance cycles of nivolumab 240 mg every 2 weeks and mocetinostat at the same dose and schedule as induction. Endpoints were toxicity, definition of a recommended phase 2 dose and preliminary assessment of response as well as correlative marker determination. Peripheral blood mononuclear blood cells from patients were tested in vitro at varying concentrations of mocetinostat, and its impact on T, regulatory T and myeloid-derived suppressor cell phenotypes were assessed by flow cytometry, as well as cytokine production by Luminex. Results: In the mocetinostat, nivolumab and ipilimumab phase I trial, 10 patients were treated, including 5 males and 5 females with a median age of 59. There were 2 complete and 5 partial responses confirmed; 6 of 7 are maintained at a median of 16 months of follow up. Three patients had progressive disease. Seven patients had grade 3-4 immune related adverse events; in 3 they were multiple. No patients died. In vitro, mocetinostat at doses from 125 to 500 nM increased relative percentage of CD4/CD8 central memory T cells, and decreased IL-6 levels while increasing interferon-gamma production (p = 0.005). Percentages of regulatory T and monocytic myeloid-derived suppressor cells were decreased by mocetinostat (p = 0.005), which also down-modulated regulatory T cell function by reducing FOXP3, HELIOS and GARP (p = 0.001). Conclusions: In vitro, mocetinostat promoted accumulation of central memory CD8 and CD4 T cells from melanoma patients, and decreased percentages and suppressive activity of T regulatory cells and myeloid-derived suppressor cells. In a pilot clinical trial, mocetinostat combined with nivolumab and ipilimumab in treatment-naïve metastatic melanoma patients exhibited a response rate of 70% with long duration of response but all ten patients treated had at least one grade 3 or 4 immune-related toxicity. De-escalation of the mocetinostat dose to 50 mg three times a week was felt to be indicated due to the toxicity of the triple regimen. Clinical trial information: NCT03565406.

Background The CXCR4-CXCL12 axis plays an important role in the chronic lymphocytic leukemia (CLL)-microenvironment interaction. Overexpression of CXCR4 has been reported in different hematological malignancies including CLL. Binding of the pro-survival chemokine CXCL12 with its cognate receptor CXCR4 induces cell migration. CXCL12/CXCR4 signaling axis promotes cell survival and proliferation and may contribute to the tropism of leukemia cells towards lymphoid tissues and bone marrow. Therefore, we hypothesized that targeting CXCR4 with an IgG1 antibody, PF-06747143, may constitute an effective therapeutic approach for CLL. Methods Patient-derived primary CLL-B cells were assessed for cytotoxicity in an in vitro model of CLL microenvironment. PF-06747143 was analyzed for cell death induction and for its potential to interfere with the chemokine CXCL12-induced mechanisms, including migration and F-actin polymerization. PF-06747143 in vivo efficacy was determined in a CLL murine xenograft tumor model. Results PF-06747143, a novel-humanized IgG1 CXCR4 antagonist antibody, induced cell death of patient-derived primary CLL-B cells, in presence or absence of stromal cells. Moreover, cell death induction by the antibody was independent of CLL high-risk prognostic markers. The cell death mechanism was dependent on CXCR4 expression, required antibody bivalency, involved reactive oxygen species production, and did not require caspase activation, all characteristics reminiscent of programmed cell death (PCD). PF-06747143 also induced potent B-CLL cytotoxicity via Fc-driven antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity activity (CDC). PF-06747143 had significant combinatorial effect with standard of care (SOC) agents in B-CLL treatment, including rituximab, fludarabine (F-ara-A), ibrutinib, and bendamustine. In a CLL xenograft model, PF-06747143 decreased tumor burden and improved survival as a monotherapy, and in combination with bendamustine. Conclusions We show evidence that PF-06747143 has biological activity in CLL primary cells, supporting a rationale for evaluation of PF-06747143 for the treatment of CLL patients. Electronic supplementary material The online version of this article (doi:10.1186/s13045-017-0435-x) contains supplementary material, which is available to authorized users.

Purpose: Checkpoint kinase 1 (Chk1) plays a critical role in the activation of mitotic spindle checkpoint and DNA damage checkpoint. We examined the preclinical use of the Chk1 inhibitor PF-00477736 as a docetaxel-sensitizing agent. Specifically, we investigated the correlation between PF-00477736–mediated modulation of biomarkers and the sensitization of docetaxel efficacy. Experimental Design: In vitro and in vivo studies using COLO205 and other cell lines were done to assess PF-00477736–induced enhancement of docetaxel efficacy and effects on associated biomarkers. Results: PF-00477736 significantly enhanced the docetaxel-induced efficacy in tumor cells and xenografts. Docetaxel induced dose- and time-dependent increase in the levels of phosphorylated Chk1 (Ser345), phosphorylated histone H3 (Ser10), and γH2AX foci and promoted the cytoplasmic localization of phosphorylated Cdc25C (Ser216). PF-00477736 cotreatment suppressed docetaxel-induced changes in phosphorylated histone H3 and cytoplasmic phosphorylated Cdc25C (Ser216) levels and concurrently sensitized the docetaxel-induced apoptosis. Docetaxel alone or in combination with PF-00477736 induced significant antiproliferative activity in xenografts, shown via [18F]FLT-PET imaging. However, changes in [18F]FLT uptake did not reflect the potentiation of docetaxel efficacy. In contrast, bioluminescence imaging showed that PF-00477736 sensitized docetaxel-induced suppression of tumor survival. Conclusions: Docetaxel triggers mitotic spindle checkpoint activation at low concentrations and activates both the DNA damage checkpoint and the spindle checkpoint at high concentrations. In combination with docetaxel, PF-00477736 abrogates the mitotic checkpoint, as well as the DNA damage checkpoint, and results in sensitization to docetaxel. Chk1 inhibitor PF-00477736 offers a therapeutic potential for the enhancement of taxane therapy.

This study was aimed at finding a correlation between the experienced off-flavor in packed foods and the presence of specific degradation products in LDPE packaging films. The possibility to trap degradation products by chemical reactions with scavengers, i.e., a zeolite additive or antioxidants, was investigated This would prevent degradation products from migrating to the polymer film surface and further into food in contact with the film. It was found that off-flavor noted in water packed in LDPE films depended on extrusion temperature and exposure time for the melt to oxygen, that is, the parameters that influence the contents of oxidation products that are able to migrate from the polymer film. It was also found that adsorption of oxidative degradation products in a zeolite additive or protection of LDPE by using antioxidants could prevent off-flavor in the packed product (water). However, the antioxidant should be selected with regard to extrusion temperature because thermal instability in the additive might jeopardize the intended effect. Multifunctional antioxidants seem to provide improved protection, the most effective one evaluated in this work being Irganox E201, i.e., vitamin E. Concentrations of oxidized degradation products are well correlated to the perceived off-flavor in the packed water. The highest correlation between off-flavor and oxidized components was found for ketones in the range of C, to C, and aldehydes in the range of C-6 to C-9. (C) 2004 Wiley Periodicals, lnc.

The chemokine receptor CXCR4 triggers signaling pathways that control cell migration to tissues where its ligand, CXCL12, is highly expressed, including the bone marrow (BM). In hematologic cancers, CXCR4 expression is associated with poor prognosis. CXCR4-driven homing of malignant cells to the BM protective niche is a key mechanism of chemotherapy resistance. PF-06747143 is a novel humanized IgG1 therapeutic antibody that binds to CXCR4 and inhibits CXCL12-driven pathways. Human IgG1 antibodies can induce strong cytotoxicity mediated by the antibody Fc-region, including antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-driven cytotoxicity, while human IgG4 antibodies show minimal or no Fc-driven cytotoxicity. Here we generated an IgG4 version of PF-06747143 (m15-IgG4), which has similar binding to CXCR4 as the IgG1 antibody. We then characterized the role of Fc-driven cytotoxic function, comparing both antibodies in efficacy and safety studies. In an ADCC assay, PF-06747143 showed strong cytotoxicity of non-Hodgkin’s lymphoma (NHL) and acute myeloid leukemia (AML), while m15-IgG4 had no significant cytotoxicity. In a NHL mouse tumor model, the IgG1 CXCR4 antibody resulted in superior tumor growth inhibition, with 50% of mice exhibiting complete tumor regressions, compared to the m15-IgG4 antibody, which had limited activity, with no tumor regressions (p 4 days. Since both antibodies had comparable exposures, the different mobilization duration is likely due to the ability of the IgG1 CXCR4 antibody to reduce the number of mobilized cells via Fc-driven cytotoxic function. Finally, CXCR4 has been shown to play a key role in chemotherapy resistance. In a chemo-resistant PDX AML mouse model, in which the standard of care agents daunorubicin and cytarabine had limited activity, resulting in 30% of tumor cells remaining in the BM post-treatment, we show that combination of PF-06747143 with these chemo agents led to synergistic activity, with tumor burden reduced to 0.3% tumor cells in the BM. In conclusion, PF-06747143 attributes offer potential efficacy- and safety-related advantages over other CXCR4 antagonists currently in development, which do not have Fc-driven cytotoxic activity. PF-06747143 is now being evaluated in a Phase 1 clinical trial in relapsed and refractory AML (NCTID 02954653). Citation Format: Flavia Pernasetti, Shu-Hui Liu, Gu Yin, Bernadette Pascual, Zhengming Yan, Max Hallin, Rolla Yafawi, Cathy Zhang, Connie Fang, Wenlian Wang, Justine Lam, Mary E. Spilker, Eileen Blasi, Brett Simmons, Nanni Huser, Wei-Hsien Ho, Kevin Lindquist, Thomas-Toan Tran, Jyothirmayee Kudaravalli, Jing-Tyan Ma, Gretchen Jimenez, Ishita Barman, Colleen Brown, Sherman-Michael Chin, Maria Costa, David Shelton, Tod Smeal, Valeria R. Fantin. Fc-effector function activity of the CXCR4 IgG1 antibody PF-06747143: a novel clinical candidate for the treatment of hematologic malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2649. doi:10.1158/1538-7445.AM2017-2649

Purpose: Axitinib (AG-013736) is a potent and selective inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinases 1 to 3 that is in clinical development for the treatment of solid tumors. We provide a comprehensive description of its in vitro characteristics and activities, in vivo antiangiogenesis, and antitumor efficacy and translational pharmacology data.Experimental Design: The potency, kinase selectivity, pharmacologic activity, and antitumor efficacy of axitinib were assessed in various nonclinical models.Results: Axitinib inhibits cellular autophosphorylation of VEGF receptors (VEGFR) with picomolar IC50 values. Counterscreening across multiple kinase and protein panels shows it is selective for VEGFRs. Axitinib blocks VEGF-mediated endothelial cell survival, tube formation, and downstream signaling through endothelial nitric oxide synthase, Akt and extracellular signal-regulated kinase. Following twice daily oral administration, axitinib produces consistent and dose-dependent antitumor efficacy that is associated with blocking VEGFR-2 phosphorylation, vascular permeability, angiogenesis, and concomitant induction of tumor cell apoptosis. Axitinib in combination with chemotherapeutic or targeted agents enhances antitumor efficacy in many tumor models compared with single agent alone. Dose scheduling studies in a human pancreatic tumor xenograft model show that simultaneous administration of axitinib and gemcitabine without prolonged dose interruption or truncation of axitinib produces the greatest antitumor efficacy. The efficacious drug concentrations predicted in nonclinical studies are consistent with the range achieved in the clinic. Although axitinib inhibits platelet-derived growth factor receptors and KIT with nanomolar in vitro potencies, based on pharmacokinetic/pharmacodynamic analysis, axitinib acts primarily as a VEGFR tyrosine kinase inhibitor at the current clinical exposure.Conclusions: The selectivity, potency for VEGFRs, and robust nonclinical activity may afford broad opportunities for axitinib to improve cancer therapy.

CXCR4 is a chemokine receptor that belongs to the G-coupled protein receptor (GPCR) family. It is over-expressed in various cancers, including solid tumors and hematological malignancies, and correlates with poor prognosis. CXCR4 expressing cells actively respond to CXCL12 (SDF-1), a chemokine constitutively secreted by stromal cells in bone marrow. Activation of CXCR4 induces cell trafficking and homing to the marrow microenvironment, where CXCL12 retains these cells in close contact with marrow stromal cells that provide growth signals, promote self-renewal, and contribute to drug resistance, leading to poor prognosis and relapse. Here we describe the generation of a highly potent and selective anti-CXCR4 humanized IgG1 antagonist Ab (PF-06747143) that binds to human CXCR4 with high affinity and blocks SDF-1-induced Calcium flux and cAMP signaling. We have also characterized the ability of PF-06747143 to induce cell death through three different mechanisms: a) mobilization of cells from CXCL12-rich niches, making them more sensitive to chemotherapy b) direct cell-death through a mechanism dependent on the antibody’s bivalency; c) ADCC- and CDC-dependent cell death through the Fc-region in IgG1 backbone, when in the presence of effector cells or serum proteins. Weekly administration of PF-06747143 at 10 mg/kg, as a monotherapy, significantly improved survival, induced sustained regression and reduced bone marrow tumor burden in various patient population relevant murine disseminated tumor models of Acute Myeloid Leukemia (MV4-11, PDXs), Non Hodgkin Lymphoma (Raji and Ramos), Chronic Lymphocytic Leukemia (JVM-13) and Multiple Myeloma (OPM-2). The CXCR4 IgG1 antibody was also shown to be similar or more efficacious than approved standards of care agents currently employed for treatment of hematological malignancies. The safety and PK/PD profile of PF-06747143 were evaluated in a Non-Human Primate (NHP) exploratory toxicology study. Results from this study indicate that the CXCR4 IgG1 Ab was well tolerated in a two-week exploratory study at pharmacologically relevant doses. Upon treatment with PF-06747143, egression of white blood cells (WBC) from bone marrow (leukocytosis) was noted, which is consistent with target (CXCR4) modulation. Following the peak of leukocytosis between 1-6 hours post antibody administration, the number of circulating WBCs rapidly decreased back to baseline levels at 24 hrs. These results are likely explained by the direct cell killing through the effector function of this IgG1 CXCR4 antibody. Altogether, the promising preclinical efficacy and safety data support clinical evaluation of PF-06747143 in hematological malignacies. Disclosures Pernasetti: Pfizer: Employment. Liu:Pfizer: Employment. Hallin:Pfizer: Employment. Gu:Pfizer: Employment. Ho:Pfizer: Employment. Zhang:Pfizer: Employment. Pascual:Pfizer: Employment. Simmons:Pfizer: Employment. Yan:Pfizer: Employment. Huser:Pfizer: Employment. Wang:Pfizer: Employment. Lam:Pfizer: Employment. Spilker:Pfizer: Employment. Blasi:Pfizer: Employment. Tran:Pfizer: Employment. Kudaravalli:Pfizer: Employment. Ma:Pfizer: Employment. Chin:Pfizer: Employment. Shelton:Pfizer: Employment. Smeal:Pfizer: Employment. Fantin:Pfizer: Employment.