Russell Pachynski

CD137 stimulation enhances the antilymphoma activity of anti-CD20 antibodies

Antibody-dependent cell-mediated cytotoxicity (ADCC), which is largely mediated by natural killer (NK) cells, is thought to play an important role in the efficacy of rituximab, an anti-CD20 monoclonal antibody (mAb) used to treat patients with B-cell lymphomas. CD137 is a costimulatory molecule expressed on a variety of immune cells after activation, including NK cells. In the present study, we show that an anti-CD137 agonistic mAb enhances the antilymphoma activity of rituximab by enhancing ADCC. Human NK cells up-regulate CD137 after encountering rituximab-coated tumor B cells, and subsequent stimulation of these NK cells with anti-CD137 mAb enhances rituximab-dependent cytotoxicity against the lymphoma cells. In a syngeneic murine lymphoma model and in a xenotransplanted human lymphoma model, sequential administration of anti-CD20 mAb followed by anti-CD137 mAb had potent antilymphoma activity in vivo. These results support a novel, sequential antibody approach against B-cell malignancies by targeting first the tumor and then the host immune system.

Redirecting migration of T cells to chemokine secreted from tumors by genetic modification with CXCR2.

T-cell-based immunotherapies provide a promising means of cancer treatment although durable antitumor responses are infrequent. A potential reason for these shortcomings may lie in the observed lack of trafficking of specific T cells to tumor. Our increasing knowledge of the process of trafficking involving adhesion molecules and chemokines affords us the opportunity to intervene and correct deficiencies in this process. Chemokines can be expressed by a range of tumors and may serve as suitable targets for directing specific T cells toward tumor. We initially sought to identify which chemokines were produced by a range of human tumor cell lines, and which chemokines and chemokine receptors were expressed by cultured T cells. We identified two chemokines: Growth-Regulated Oncogene-alpha (Gro-alpha; CXCL1) and Regulated on Activation Normal T Cell-Expressed and Secreted (RANTES; CCL5), to be secreted by several human tumor cell lines. Expression was also detected in fine-needle aspirates of melanoma from patients. In addition, we determined the expression of several chemokine receptors on cultured human T cells including CCR1, CCR2, CCR4, CCR5, CXCR3, and CXCR4. Cultured, activated human T cells expressed the chemokines lymphotactin (XCL1), RANTES, macrophage inflammatory protein-1 alpha (MIP-1 alpha; CCL3) and MIP-1 beta (CCL4), but no appreciable Gro-alpha. In a strategy to direct T cells toward chemokines expressed by tumors we chose Gro-alpha as the target chemokine because it was produced by tumor and not by T cells themselves. However, T cells did not express the receptor for Gro-alpha, CXCR2, and therefore, T cells were transduced with a retroviral vector encoding CXCR2. Calcium ion mobilization, an important first step in chemokine receptor signaling, was subsequently demonstrated in transduced T cells in response to Gro-alpha. In addition, Gro-alpha was chemotactic for T cells expressing CXCR2 in vitro toward both recombinant protein and tumor-derived chemokine. Interestingly we demonstrate, for the first time, that Gro-alpha was able to induce interferon-gamma (IFN-gamma) secretion from transduced T cells, thereby extending our knowledge of other potential functions of CXCR2. This study demonstrates the feasibility of redirecting the migration properties of T cells toward chemokines secreted by tumors.

Plasmacytoid dendritic cells transport peripheral antigens to the thymus to promote central tolerance.

Central tolerance can be mediated by peripheral dendritic cells (DCs) that transport innocuous antigens (Ags) to the thymus for presentation to developing T cells, but the responsible DC subsets remained poorly defined. Immature plasmacytoid DCs (pDCs) express CCR9, a chemokine receptor involved in migration of T cell precursors to the thymus. We show here that CCR9 mediated efficient thymic entry of endogenous or i.v. transfused pDCs. pDCs activated by Toll-like receptor (TLR) ligands downregulated CCR9 and lost their ability to home to the thymus. Moreover, endogenous pDCs took up subcutaneously injected fluorescent Ag and, in the absence of TLR signals, transported Ag to the thymus in a CCR9-dependent fashion. Injected, Ag-loaded pDCs effectively deleted Ag-specific thymocytes, and this thymic clonal deletion required CCR9-mediated homing and was prevented by infectious signals. Thus, peripheral pDCs can contribute to immune tolerance through CCR9-dependent transport of peripheral Ags and subsequent deletion of Ag-reactive thymocytes.

Extranodal dissemination of non-Hodgkin lymphoma requires CD47 and is inhibited by anti-CD47 antibody therapy.

Non-Hodgkin lymphoma (NHL) presents as both localized and disseminated disease with spread to secondary sites carrying a worse prognosis. Although pathways driving NHL dissemination have been identified, there are few therapies capable of inhibiting them. Here, we report a novel role for the immunomodulatory protein CD47 in NHL dissemination, and we demonstrate that therapeutic targeting of CD47 can prevent such spread. We developed 2 in vivo lymphoma metastasis models using Raji cells, a human NHL cell line, and primary cells from a lymphoma patient. CD47 expression was required for Raji cell dissemination to the liver in mouse xenotransplants. Targeting of CD47 with a blocking antibody inhibited Raji cell dissemination to major organs, including the central nervous system, and inhibited hematogenous dissemination of primary lymphoma cells. We hypothesized that anti-CD47 antibody-mediated elimination of circulating tumor cells occurred through phagocytosis, a previously described mechanism for blocking anti-CD47 antibodies. As predicted, inhibition of dissemination by anti-CD47 antibodies was dependent on blockade of phagocyte SIRPα and required macrophage effector cells. These results demonstrate that CD47 is required for NHL dissemination, which can be therapeutically targeted with a blocking anti-CD47 antibody. Ultimately, these findings are potentially applicable to the dissemination and metastasis of other solid tumors.

The chemoattractant chemerin suppresses melanoma by recruiting natural killer cell antitumor defenses

Chemerin recruits NK cells to suppress melanoma growth.

Role of Antigen Spread and Distinctive Characteristics of Immunotherapy in Cancer Treatment

Immunotherapy is an important breakthrough in cancer. US Food and Drug Administration-approved immunotherapies for cancer treatment (including, but not limited to, sipuleucel-T, ipilimumab, nivolumab, pembrolizumab, and atezolizumab) substantially improve overall survival across multiple malignancies. One mechanism of action of these treatments is to induce an immune response against antigen-bearing tumor cells; the resultant cell death releases secondary (nontargeted) tumor antigens. Secondary antigens prime subsequent immune responses (antigen spread). Immunotherapy-induced antigen spread has been shown in clinical studies. For example, in metastatic castration-resistant prostate cancer patients, sipuleucel-T induced early immune responses to the immunizing antigen (PA2024) and/or the target antigen (prostatic acid phosphatase). Thereafter, most patients developed increased antibody responses to numerous secondary proteins, several of which are expressed in prostate cancer with functional relevance in cancer. The ipilimumab-induced antibody profile in melanoma patients shows that antigen spread also occurs with immune checkpoint blockade. In contrast to chemotherapy, immunotherapy often does not result in short-term changes in conventional disease progression end points (eg, progression-free survival, tumor size), which may be explained, in part, by the time taken for antigen spread to occur. Thus, immune-related response criteria need to be identified to better monitor the effectiveness of immunotherapy. As immunotherapy antitumor effects take time to evolve, immunotherapy in patients with less advanced cancer may have greater clinical benefit vs those with more advanced disease. This concept is supported by prostate cancer clinical studies with sipuleucel-T, PSA-TRICOM, and ipilimumab. We discuss antigen spread with cancer immunotherapy and its implications for clinical outcomes.

Abstract CT116: BMS-986205, an optimized indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor, is well tolerated with potent pharmacodynamic (PD) activity, alone and in combination with nivolumab (nivo) in advanced cancers in a phase 1/2a trial

Background: IDO1 is highly expressed in multiple cancers and may be an immunosuppressive mechanism for tumor escape via its production of metabolites that inhibit T-cell function. Nivo, a mAb that targets PD-1, causes IDO1 upregulation, supporting a rationale for combining it with an IDO1 inhibitor. Our preclinical program aimed to identify a best in class IDO1 inhibitor with favorable pharmacokinetic (PK) characteristics (Hunt J, et al. AACR 2017 [abst 6774]). Here we present BMS-986205, a selective IDO1 inhibitor validated in a novel phase 1/2a trial alone and in combination with nivo. Methods: During dose escalation, patients (pts) with advanced cancers were treated in escalating cohorts with BMS-986205 (25-200 mg as of Jan 5, 2017) orally once daily (QD) for 2 wk, followed by BMS-986205 + nivo 240 mg IV every 2 wk. Objectives included safety (primary), PK, and PD. Preclinical analyses included measurement of enzyme inhibition in HEK293 cells overexpressing human IDO1 or tryptophan 2,3-dioxygenase (TDO) and IFNγ-stimulated HeLa cells. Results: In support of clinical testing, BMS-986205 was evaluated preclinically. In vitro characteristics included potent inhibition of kynurenine (kyn) production in IDO1-HEK293 cells (IC50 = 1.1 nM) but not in TDO-HEK293 cells, sustained inhibition in IDO1 cell-based assays after washout, and single-digit nM potency in human tolerogenic MLR assays. Based on preclinical data, a 150 mg QD human dose was projected to maximally inhibit IDO1. In the ongoing clinical study, 42 pts have been treated. All treatment-related adverse events were grade 1/2 except three grade 3 toxicities (autoimmune hepatitis [dose limiting; BMS-986205 100 mg/nivo 240 mg], rash, and asymptomatic hypophosphatemia). Day 14 individual trough concentrations began exceeding the human whole blood IC50 starting with 25 mg QD, and the IC90 starting with 50 mg QD; all pts treated at 200 mg QD exceeded the IC90. Serum kyn was substantially reduced at all doses (> 45% mean reduction at each dose), with > 60% mean reduction at the 100 and 200 mg QD doses. Importantly, intratumoral kyn was reduced up to 90% in evaluable paired pre- and on-treatment samples. Conclusions: BMS-986205 is an optimized, once-daily, selective and potent oral IDO1 inhibitor at clinically relevant concentrations. It is well tolerated up to at least 200 mg in combination with nivo in this novel trial. Evidence of substantial serum kyn reduction was observed at doses as low as 25 mg QD; inhibition at 100 and 200 mg QD appears greater than that reported for other in-class compounds. In addition, we have presented the first evidence of intratumoral kyn reduction by an IDO1 inhibitor. These data suggest the potential of BMS-986205 as an IDO1 inhibitor with superior PD properties and support further evaluation in combination with nivo. Citation Format: Lillian L. Siu, Karen Gelmon, Quincy Chu, Russell Pachynski, Olatunji Alese, Paul Basciano, Justine Walker, Priyam Mitra, Li Zhu, Penny Phillips, John Hunt, Jayesh Desai. BMS-986205, an optimized indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor, is well tolerated with potent pharmacodynamic (PD) activity, alone and in combination with nivolumab (nivo) in advanced cancers in a phase 1/2a trial [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 CT116. doi:10.1158/1538-7445.AM2017-CT116

Phase II Study of Pazopanib and Paclitaxel in Patients With Refractory Urothelial Cancer

INTRODUCTION Currently, no standard treatments are available for relapsed or refractory urothelial carcinoma (UC). Paclitaxel has demonstrated efficacy in the treatment of UC when used alone or combined with other cytotoxic therapies. We designed a phase II trial combining paclitaxel with pazopanib, a commonly used antiangiogenic agent with significant antitumor activity in various solid tumors. PATIENTS AND METHODS We enrolled 32 patients with refractory UC who had demonstrated disease progression after 2 previous chemotherapeutic regimens. The patients received paclitaxel 80 mg/m2 on days 1, 8, and 15 of a 28-day cycle and oral pazopanib 800 mg daily. The primary endpoint was the overall response rate (ORR). The secondary endpoints included progression-free survival, overall survival, and a safety assessment of the combination. RESULTS Of the 28 evaluable patients, a complete response was observed in 3 patients and a partial response in 12, with an ORR of 54% (95% confidence interval, 33.9-72.5). The median progression-free and overall survival was 6.2 and 10 months, respectively. The most frequent side effects noted (all grades) were fatigue (63%), diarrhea (44%), and nausea and vomiting (41%). Hematologic toxicities were common and included (all grades) anemia (69%), neutropenia (38%), and thrombocytopenia (47%). Growth factor support was required for 44% of the patients. CONCLUSION The combination of paclitaxel and pazopanib resulted in a promising ORR of 54% in patients with advanced pretreated UC. This represents a greater response rate and median survival than found with other existing second-line regimens for UC and is worthy of further study.

Contemporary Management of the Newly Diagnosed Prostate Cancer Patient with Metastatic Disease at Presentation

Purpose of ReviewAndrogen deprivation therapy (ADT) has been the standard-of-care (SOC) for metastatic hormone-sensitive prostate cancer (mHSPC) since the middle of the twentieth century. Recently, several practice-changing trials have added new therapy options for these patients. Here we review these studies and discuss guidelines on treatment decision-making.Recent FindingsA trio of studies (GETUG-AFU15, STAMPEDE, CHAARTED) combining docetaxel chemotherapy with ADT all showed clinical benefit of the addition. More recently, the LATITUDE and STAMPEDE-Abiraterone studies established yet another new option for up-front treatment of newly diagnosed metastatic prostate cancer, showing significantly prolonged overall survival (OS) and progression-free survival (PFS) compared to ADT alone in men with high-risk mHSPC.SummaryWith the recent demonstration that adding either docetaxel or abiraterone plus prednisone to ADT significantly improves survival in mHSPC, physicians are confronted by a growing body of clinical data and treatment regimens. Men with high-volume and/or high-risk metastatic disease should not be treated with ADT alone without strong consideration of docetaxel or abiraterone. The choice of a first-line therapy should be made based on risk stratification, patients’ comorbidities, toxicities, quality-of-life (QOL) considerations, and cost.

MP87-17 PROSTATE MRI REPRESENTS LEUKOCYTE DENSITY AND NOT THE PRESENCE OF CANCER ON BIOPSY

INTRODUCTION AND OBJECTIVES: Despite the role of interferon-g (IFNg) in tumor immune surveillance; studies have implicated the dark side of IFNg based on its pro-tumorigenic activity. IFNg can induce transcriptional activation of IFN-stimulated genes (ISGs) via JAK-STAT signaling pathway. The most highly induced ISGs are interferon-induced tetratricopeptide repeat (IFIT) family members. By studying a differential regulation on a unique tumor suppressor miR-363 from its polycistronic miR-106a-363 cluster, we unveiled a new microRNA (miRNA) turnover machinery composed of IFIT5, which is first described as a viral RNA binding protein. Up to date, the impact of IFIT5 on cancer metastasis is unclear. METHODS: Luciferase reporter gene assay was for examining the IFNg-induced IFIT5 gene activation. Transwell migration assay was for demonstrating the function of IFIT5 with cancer metastasis. Sitedirected mutagenesis, in vitro transcription, RNA pull down and in vitro RNA degradation assay were for determining the specificity of miRNA species regulated by IFIT5-mediated turnover machinery. RESULTS: IFIT5 gene promoter activity and protein level were significantly elevated by IFNg. IFIT5 complex represents unique posttranscriptional machinery for turnover of a specific population of tumor suppressor miRNAs. We examined several IFIT5-regulated miRNA candidates, and found IFNg can suppress miR-101, miR-335, miR-203, and miR-128, and phenocopied the miRNA expression profile of IFIT5overexpressing cells. Seed regions of miR-101 and miR-128 have sequence-matched target sites at ZEB1 mRNA 30UTR, and indeed can suppress ZEB1. Meanwhile, IFIT5 is elevated in higher grade prostatic tumors, and positively correlated with ZEB1, ZEB2 and Slug in prostate cancer. Knockdown of IFIT5 lead to suppression of ZEB1 and Slug, along with decreased migration mobility in cancer cells. On the contrary, IFNg treatment enhanced cell migration, and this effect is diminished by the loss of IFIT5. We also modified the 50end structure of precursor miR101 and miR-128, and examined its regulation by IFIT5-mediated miRNA turnover machinery. Both pre-miR-101 and pre-miR-128 with mutated blunt end are resistant to degradation in an IFIT5-expressing PC3 cell and show greater impact on suppressing cell migration, compared to the mutant precursor with single stranded overhang. CONCLUSIONS: We demonstrated that IFNg potentiate prostate cancer metastasis via IFIT5-mediated miRNA turnover machinery, which regulates specific tumor suppressor miRNAs that target critical EMT factors including ZEB1 and Slug.