Identification of NRAS isoform 2 overexpression as a mechanism facilitating BRAF inhibitor resistance in malignant melanoma

Activating mutations in BRAF are found in 50% of melanomas and although treatment with BRAF inhibitors (BRAFi) is effective, resistance often develops. We now show that recently discovered NRAS isoform 2 is up-regulated in the setting of BRAF inhibitor resistance in melanoma, in both cell lines and patient tumor tissues. When isoform 2 was overexpressed in BRAF mutant melanoma cell lines, melanoma cell proliferation and in vivo tumor growth were significantly increased in the presence of BRAFi treatment. shRNA-mediated knockdown of isoform 2 in BRAFi resistant cells restored sensitivity to BRAFi compared with controls. Signaling analysis indicated decreased mitogen-activated protein kinase (MAPK) pathway signaling and increased phosphoinositol-3-kinase (PI3K) pathway signaling in isoform 2 overexpressing cells compared with isoform 1 overexpressing cells. Immunoprecipitation of isoform 2 validated a binding affinity of this isoform to both PI3K and BRAF/RAF1. The addition of an AKT inhibitor to BRAFi treatment resulted in a partial restoration of BRAFi sensitivity in cells expressing high levels of isoform 2. NRAS isoform 2 may contribute to resistance to BRAFi by facilitating PI3K pathway activation.

MICA-Expressing Monocytes Enhance Natural Killer Cell Fc Receptor-Mediated Antitumor Functions

Natural killer (NK) cells are large granular lymphocytes that promote the antitumor response via communication with other cell types in the tumor microenvironment. Previously, we have shown that NK cells secrete a profile of immune stimulatory factors (e.g., IFNγ, MIP-1α, and TNFα) in response to dual stimulation with the combination of antibody (Ab)-coated tumor cells and cytokines, such as IL12. We now demonstrate that this response is enhanced in the presence of autologous monocytes. Monocyte enhancement of NK cell activity was dependent on cell-to-cell contact as determined by a Transwell assay. It was hypothesized that NK cell effector functions against Ab-coated tumor cells were enhanced via binding of MICA on monocytes to NK cell NKG2D receptors. Strategies to block MICA-NKG2D interactions resulted in reductions in IFNγ production. Depletion of monocytes in vivo resulted in decreased IFNγ production by murine NK cells upon exposure to Ab-coated tumor cells. In mice receiving trastuzumab and IL12 therapy, monocyte depletion resulted in significantly greater tumor growth in comparison to mock-depleted controls (P < 0.05). These data suggest that NK cell-monocyte interactions enhance NK cell antitumor activity in the setting of monoclonal Ab therapy for cancer. Cancer Immunol Res; 5(9); 778-89. ©2017 AACR.

Novel rodent model of breast cancer survival with persistent anxiety-like behavior and inflammation

Breast cancer survivors are an expanding population that is troubled by lasting mental health problems, including depression and anxiety. These issues reduce quality-of-life throughout survivorhood. Research indicates that tumor biology, cancer treatments, and stress contribute to these mood disturbances. Although the mechanisms underlying these various causes remain under investigation, neuroinflammation is a leading hypothesis. To date, rodent models of recurrence-free tumor survival for understanding mechanisms by which these behavioral issues persist after cancer are lacking. Here, we test the extent to which potential behavioral symptoms persist after mammary tumor removal in mice (i.e., establishment of a cancer survivor model), while also empirically testing the causal role of tumors in the development of neuroinflammatory-mediated affective-like behaviors. Complete surgical resection of a non-metastatic orthotopic, syngeneic mammary tumor reversed tumor-induced increases of circulating cytokines (IL-6, CXCL1, IL-10) and myeloid-derived cells and modulated neuroinflammatory gene expression (Cd11b, Cxcl1). Multiple anxiety-like behaviors and some central and peripheral immune markers persisted or progressed three weeks after tumor resection. Together, these data indicate that persistent behavioral changes into cancer survivorhood may be due, in part, to changes in immunity that remain even after successful tumor removal. This novel survivor paradigm represents an improvement in modeling prevalent cancer survivorship issues and studying the basic mechanisms by which cancer/cancer treatments influence the brain and behavior.

Circulating myeloid-derived suppressor cells increase in patients undergoing neo-adjuvant chemotherapy for breast cancer

This study sought to evaluate whether myeloid-derived suppressor cells (MDSC) could be affected by chemotherapy and correlate with pathologic complete response (pCR) in breast cancer patients receiving neo-adjuvant chemotherapy. Peripheral blood levels of granulocytic (G-MDSC) and monocytic (M-MDSC) MDSC were measured by flow cytometry prior to cycle 1 and 2 of doxorubicin and cyclophosphamide and 1st and last administration of paclitaxel or paclitaxel/anti-HER2 therapy. Of 24 patients, 11, 6 and 7 patients were triple negative, HER2+ and hormone receptor+, respectively. 45.8% had pCR. Mean M-MDSC% were <1. Mean G-MDSC% and 95% confidence intervals were 0.88 (0.23-1.54), 5.07 (2.45-7.69), 9.32 (4.02-14.61) and 1.97 (0.53-3.41) at draws 1-4. The increase in G-MDSC by draw 3 was significant (p < 0.0001) in all breast cancer types. G-MDSC levels at the last draw were numerically lower in patients with pCR (1.15; 95% CI 0.14-2.16) versus patients with no pCR (2.71; 95% CI 0-5.47). There was no significant rise in G-MDSC from draw 1 to 3 in African American patients, and at draw 3 G-MDSC levels were significantly lower in African Americans versus Caucasians (p < 0.05). It was concluded that G-MDSC% increased during doxorubicin and cyclophosphamide therapy, but did not significantly differ between patients based on pathologic complete response.

Safety and Activity of Varlilumab, a Novel and First-in-Class Agonist Anti-CD27 Antibody, in Patients With Advanced Solid Tumors

Purpose

CD27, a costimulatory molecule on T cells, induces intracellular signals that mediate cellular activation, proliferation, effector function, and cell survival upon binding to its ligand, CD70. Varlilumab is a novel, first-in-class, agonist CD27 antibody that stimulates the CD27 pathway, which results in T-cell activation and antitumor activity in tumor models. This first-in-human, dose-escalation and expansion study evaluated the safety, pharmacology, and activity of varlilumab in patients with advanced solid tumors.

Methods

In a 3 + 3 dose-escalation design (n = 25), patients received a single dose of varlilumab (0.1, 0.3, 1.0, 3.0, or 10 mg/kg intravenously) with a 28-day observation, followed by up to five multidose cycles (one dose per week for 4 weeks), depending on tumor response. Expansion cohorts were initiated at 3.0 mg/kg in patients with melanoma (n = 16) and renal cell carcinoma (RCC; n = 15). Primary objectives were to assess the safety and the maximum tolerated and optimal biologic doses of varlilumab. Secondary objectives were to evaluate the pharmacokinetics, pharmacodynamics, and clinical antitumor activity of varlilumab.

Results

Exposure to varlilumab was linear and dose proportional across dose groups. Only one patient experienced a dose-limiting toxicity—grade 3 transient asymptomatic hyponatremia at the 1.0-mg/kg dose level. Treatment-related adverse events were generally grade 1 or 2 in severity. Evidence of biologic activity consistent with CD27 stimulation—chemokine induction, T-cell stimulation, regulatory T cell depletion—was observed at all dose levels. A patient with metastatic RCC experienced a partial response (78% shrinkage, progression-free survival > 2.3 years). Eight patients experienced stable disease > 3 months, including a patient with metastatic RCC with progression-free survival of > 3.9 years.

Conclusion

Dose escalation of varlilumab to 10 mg/kg was well tolerated without identification of a maximum tolerated dose. Varlilumab was biologically and clinically active.

Soy isoflavones and their metabolites modulate cytokine-induced NK cell function

Soybeans and foods derived from them are a rich source of phytochemicals that have been linked with beneficial effects on obesity, cancer, and inflammation. It is postulated that these immunomodulatory properties in particular, may contribute to their health promoting effects. However, the impact of soy bioactives on the functional properties of immune cell subsets is not fully understood. Upon ingestion, the profile of bioactive compounds derived from soy becomes increasingly complex. For example, soy isoflavones (genistein and daidzein) can be differentially metabolized by distinct populations of gut microbiota which promote their metabolism into compounds as O-desmethylangolensin (O-DMA) and equol. We hypothesized that soy phytochemicals alter natural killer (NK) cell signaling and function. Soy isoflavones and their metabolites did not alter the viability of healthy donor PBMC, even at high (25μM) concentrations. However, pre-treatment of PBMC with genistein (p=0.0009) and equol (p=0.002) decreased IL-12/18 induced IFN-γ production compared to controls. Genistein (p=0.002) and equol (p=0.0006) also decreased IL-12/18-induced IFN-γ production by human NK cells but did not alter cytotoxicity. Furthermore, in vivo studies revealed that C57BL/6 mice fed a soy-enriched diet produced less IFN-γ in plasma following administration of IL-12/IL-18 as compared to control-fed animals (p&lt;0.0001). This study provides insight into how dietary soy modulates NK cell functions and suggest the use of soy may interact with during chemopreventive or immune based therapies that act via NK cells.

Immunotherapy of head and neck cancer: Emerging clinical trials from a National Cancer Institute Head and Neck Cancer Steering Committee Planning Meeting

Recent advances have permitted successful therapeutic targeting of the immune system in head and neck squamous cell carcinoma (HNSCC). These new immunotherapeutic targets and agents are being rapidly adopted by the oncologic community and hold considerable promise. The National Cancer Institute sponsored a Clinical Trials Planning Meeting to address the issue of how to further investigate the use of immunotherapy in patients with HNSCC. The goals of the meeting were to consider phase 2 or 3 trial designs primarily in 3 different patient populations: those with previously untreated, human papillomavirus-initiated oropharyngeal cancers; those with previously untreated, human papillomavirus-negative HNSCC; and those with recurrent/metastatic HNSCC. In addition, a separate committee was formed to develop integrative biomarkers for the clinical trials. The meeting started with an overview of key immune components and principles related to HNSCC, including immunosurveillance and immune escape. Four clinical trial concepts were developed at the meeting integrating different immunotherapies with existing standards of care. These designs were presented for implementation by the head and neck committees of the National Cancer Institute-funded National Clinical Trials Network. This article summarizes the proceedings of this Clinical Trials Planning Meeting, the purpose of which was to facilitate the rigorous development and design of randomized phase 2 and 3 immunotherapeutic trials in patients with HNSCC. Although reviews usually are published immediately after the meeting is held, this report is unique because there are now tangible clinical trial designs that have been funded and put into practice and the studies are being activated to accrual. Cancer 2017;123:1259-1271. © 2016 American Cancer Society.

Skin cancer screening: recommendations for data-driven screening guidelines and a review of the US Preventive Services Task Force controversy

Melanoma is usually apparent on the skin and readily detected by trained medical providers using a routine total body skin examination, yet this malignancy is responsible for the majority of skin cancer-related deaths. Currently, there is no national consensus on skin cancer screening in the USA, but dermatologists and primary care providers are routinely confronted with making the decision about when to recommend total body skin examinations and at what interval. The objectives of this paper are: to propose rational, risk-based, data-driven guidelines commensurate with the US Preventive Services Task Force screening guidelines for other disorders; to compare our proposed guidelines to recommendations made by other national and international organizations; and to review the US Preventive Services Task Force's 2016 Draft Recommendation Statement on skin cancer screening.

Plasma MicroRNA Levels Following Resection of Metastatic Melanoma

Melanoma remains the leading cause of skin cancer–related deaths. Surgical resection and adjuvant therapies can result in disease-free intervals for stage III and stage IV disease; however, recurrence is common. Understanding microRNA (miR) dynamics following surgical resection of melanomas is critical to accurately interpret miR changes suggestive of melanoma recurrence. Plasma of 6 patients with stage III (n = 2) and stage IV (n = 4) melanoma was evaluated using the NanoString platform to determine pre- and postsurgical miR expression profiles, enabling analysis of more than 800 miRs simultaneously in 12 samples. Principal component analysis detected underlying patterns of miR expression between pre- vs postsurgical patients. Group A contained 3 of 4 patients with stage IV disease (pre- and postsurgical samples) and 2 patients with stage III disease (postsurgical samples only). The corresponding preoperative samples to both individuals with stage III disease were contained in group B along with 1 individual with stage IV disease (pre- and postsurgical samples). Group A was distinguished from group B by statistically significant analysis of variance changes in miR expression (P < .0001). This analysis revealed that group A vs group B had downregulation of let-7b-5p, miR-520f, miR-720, miR-4454, miR-21-5p, miR-22-3p, miR-151a-3p, miR-378e, and miR-1283 and upregulation of miR-126-3p, miR-223-3p, miR-451a, let-7a-5p, let-7g-5p, miR-15b-5p, miR-16-5p, miR-20a-5p, miR-20b-5p, miR-23a-3p, miR-26a-5p, miR-106a-5p, miR-17-5p, miR-130a-3p, miR-142-3p, miR-150-5p, miR-191-5p, miR-199a-3p, miR-199b-3p, and miR-1976. Changes in miR expression were not readily evident in individuals with distant metastatic disease (stage IV) as these individuals may have prolonged inflammatory responses. Thus, inflammatory-driven miRs coinciding with tumor-derived miRs can blunt anticipated changes in expression profiles following surgical resection.

Phase III Randomized Study of 4 Weeks of High-Dose Interferon-α-2b in Stage T2bNO, T3a-bNO, T4a-bNO, and T1-4N1a-2a (microscopic) Melanoma: A Trial of the Eastern Cooperative Oncology Group-American College of Radiology Imaging Network Cancer Research Group (E1697)

Purpose To test the efficacy of 4 weeks of intravenous (IV) induction with high-dose interferon (IFN) as part of the Eastern Cooperative Oncology Group regimen compared with observation (OBS) in patients with surgically resected intermediate-risk melanoma. Patients and Methods In this intergroup international trial, eligible patients had surgically resected cutaneous melanoma in the following categories: (1) T2bN0, (2) T3a-bN0, (3) T4a-bN0, and (4) T1-4N1a-2a (microscopic). Patients were randomly assigned to receive IFN α-2b at 20 MU/m²/d IV for 5 days (Monday to Friday) every week for 4 weeks (IFN) or OBS. Stratification factors were pathologic lymph node status, lymph node staging procedure, Breslow depth, ulceration of the primary lesion, and disease stage. The primary end point was relapse-free survival. Secondary end points included overall survival, toxicity, and quality of life. Results A total of 1,150 patients were randomly assigned. At a median follow-up of 7 years, the 5-year relapse-free survival rate was 0.70 (95% CI, 0.66 to 0.74) for OBS and 0.70, (95% CI, 0.66 to 0.74) for IFN ( P = .964). The 5-year overall survival rate was 0.83 (95% CI, 0.79 to 0.86) for OBS and 0.83 (95% CI, 0.80 to 0.86) for IFN ( P = .558). Treatment-related grade 3 and higher toxicity was 4.6% versus 57.9% for OBS and IFN, respectively ( P < .001). Quality of life was worse for the treated group. Conclusion Four weeks of IV induction as part of the Eastern Cooperative Oncology Group high-dose IFN regimen is not better than OBS alone for patients with intermediate-risk melanoma as defined in this trial.

Inflammatory Cytokines and Comorbidity Development in Breast Cancer Survivors Versus Noncancer Controls: Evidence for Accelerated Aging?

Purpose The sequelae of cancer treatment may increase systemic inflammation and create a phenotype at increased risk of functional decline and comorbidities, leading to premature mortality. Little is known about how this trajectory compares with natural aging among peers of the same age without cancer. This longitudinal study investigated proinflammatory cytokines and comorbidity development over time among breast cancer survivors and a noncancer control group. Methods Women (N = 315; 209 with breast cancer and 106 in the control group) were recruited at the time of their work-up for breast cancer; they completed the baseline questionnaire, interview, and blood draw (lipopolysaccharide-stimulated production of interleukin [IL] -6, tumor necrosis factor-α, and IL-1β). Measures were repeated 6 and 18 months after primary cancer treatment (cancer survivors) or within a comparable time frame (control group). Results There were no baseline differences in comorbidities or cytokines between survivors and the control group. Over time, breast cancer survivors had significantly higher tumor necrosis factor-α and IL-6 compared with the control group. Survivors treated with surgery, radiation, and chemotherapy accumulated a significantly greater burden of comorbid conditions and suffered greater pain associated with inflammation over time after cancer treatment than did the control group. Conclusion Survivors who had multimodal treatment had higher cytokines and comorbidities, suggestive of accelerated aging. Comorbidities were related to inflammation in this sample, which could increase the likelihood of premature mortality. Given that many comorbidities take years to develop, future research with extended follow-up beyond 18 months is necessary to examine the evidence of accelerated aging in cancer survivors and to determine the responsible mechanisms.

Interferon-γ Promotes Antibody-mediated Fratricide of Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is characterized by the proliferation of immature myeloid lineage blasts. Due to its heterogeneity and to the high rate of acquired drug resistance and relapse, new treatment strategies are needed. Here, we demonstrate that IFNγ promotes AML blasts to act as effector cells within the context of antibody therapy. Treatment with IFNγ drove AML blasts toward a more differentiated state, wherein they showed increased expression of the M1-related markers HLA-DR and CD86, as well as of FcγRI, which mediates effector responses to therapeutic antibodies. Importantly, IFNγ was able to up-regulate CD38, the target of the therapeutic antibody daratumumab. Because the antigen (CD38) and effector receptor (FcγRI) were both simultaneously up-regulated on the AML blasts, we tested whether IFNγ treatment of the AML cell lines THP-1 and MV4-11 could stimulate them to target one another after the addition of daratumumab. Results showed that IFNγ significantly increased daratumumab-mediated cytotoxicity, as measured both by ⁵¹Cr release and lactate dehydrogenase release assays. We also found that the combination of IFNγ and activation of FcγR led to the release of granzyme B by AML cells. Finally, using a murine NSG model of subcutaneous AML, we found that treatment with IFNγ plus daratumumab significantly attenuated tumor growth. Taken together, these studies show a novel mechanism of daratumumab-mediated killing and a possible new therapeutic strategy for AML.

MicroRNA profiling of patient plasma for clinical trials using bioinformatics and biostatistical approaches

Background

MicroRNAs (miRNAs) are short noncoding RNAs that function to repress translation of mRNA transcripts and contribute to the development of cancer. We hypothesized that miRNA array-based technologies work best for miRNA profiling of patient-derived plasma samples when the techniques and patient populations are precisely defined.

Methods

Plasma samples were obtained from five sources: melanoma clinical trial of interferon and bortezomib (12), purchased normal donor plasma samples (four), gastrointestinal tumor bank (nine), melanoma tumor bank (ten), or aged-matched normal donors (eight) for the tumor bank samples. Plasma samples were purified for miRNAs and quantified using NanoString^® arrays or by the company Exiqon. Standard biostatistical array approaches were utilized for data analysis and compared to a rank-based analytical approach.

Results

With the prospectively collected samples, fewer plasma samples demonstrated visible hemolysis due to increased attention to eliminating factors, such as increased pressure during phlebotomy, small gauge needles, and multiple punctures. Cancer patients enrolled in a melanoma clinical study exhibited the clearest pattern of miRNA expression as compared to normal donors in both the rank-based analytical method and standard biostatistical array approaches. For the patients from the tumor banks, fewer miRNAs (<5) were found to be differentially expressed and the false positive rate was relatively high.

Conclusion

In order to obtain consistent results for NanoString miRNA arrays, it is imperative that patient cohorts have similar clinical characteristics with a uniform sample preparation procedure. A clinical workflow has been optimized to collect patient samples to study plasma miRNAs.

NCCN Oncology Research Program's Investigator Steering Committee and NCCN Best Practices Committee Molecular Profiling Surveys

BACKGROUND

With advances such as next-generation sequencing (NGS) increasing understanding of the basis of cancer and its response to treatment, NCCN believes it is important to understand how molecular profiling/diagnostic testing is being performed and used at NCCN Member Institutions and their community affiliates.

METHODS

The NCCN Oncology Research Program's Investigator Steering Committee and the NCCN Best Practices Committee gathered baseline information on the use of cancer-related molecular testing at NCCN Member Institutions and community members of the NCCN Affiliate Research Consortium through 2 separate surveys distributed in December 2013 and September 2014, respectively.

RESULTS

A total of 24 NCCN Member Institutions and 8 affiliate sites provided quantitative and qualitative data. In the context of these surveys, "molecular profiling/diagnostics" was defined as a panel of at least 10 genes examined as a diagnostic DNA test in a Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory.

CONCLUSIONS

Results indicated that molecular profiling/diagnostics are used at 100% of survey respondents' institutions to make patient care decisions. However, challenges relating to reimbursement, lack of data regarding actionable targets and targeted therapies, and access to drugs on or off clinical trials were cited as barriers to integration of molecular profiling into patient care. Frameworks for using molecular diagnostic results based on levels of evidence, alongside continued research into the predictive value of biomarkers and targeted therapies, are recommended to advance understanding of the role of genomic biomarkers. Greater evidence and consensus regarding the clinical and cost-effectiveness of molecular profiling may lead to broader insurance coverage and increased integration into patient care.

Folate-conjugated immunoglobulin targets melanoma tumor cells for NK cell effector functions

The folate receptor (FR) is overexpressed on the vascular side of cancerous cells including those of the breast, ovaries, testes, and cervix. We hypothesized that a folate-conjugated immunoglobulin (F-IgG) would bind to the FR that is overexpressed on melanoma tumor cells to target these cells for lysis by natural killer (NK) cells. Folate receptor expression was confirmed in the Mel-39 (human melanoma) cell line by flow cytometry and immunoblot analysis using KB (human oral epithelial) and F01 (human melanoma) as a positive and a negative control, respectively. FR-positive and FR-negative cell lines were treated with F-IgG or control immunoglobulin G in the presence or absence of cytokines to determine NK cell ability to lyse FR-positive cell lines. NK cell activation was significantly upregulated and lysis of Mel 39 tumor cells increased following treatment with F-IgG compared with control immunoglobulin G at all effector : target (E : T) ratios (P<0.01). This trend further increased by NK cell stimulation with the activating cytokine interleukin-12. NK cell production of cytokines such as interferon-gamma, macrophage inflammatory protein 1α, and regulated on activation normal T-cell expressed and secreted (RANTES) was also significantly increased in response to costimulation with interleukin-12 stimulation and F-IgG-coated Mel 39 target cells compared with controls (P<0.01). In contrast, F-IgG did not bind to the FR-negative cell line F01 and had no significant effect on NK cell lysis or cytokine production. This research indicates the potential use of F-IgG for its ability to induce an immune response from NK cells against FR-positive melanoma tumor cells, which can be further increased by the addition of cytokines.

A Phase I Trial to Evaluate Antibody-Dependent Cellular Cytotoxicity of Cetuximab and Lenalidomide in Advanced Colorectal and Head and Neck Cancer

mAbs can induce antibody-dependent cellular cytotoxicity (ADCC) via the innate immune system's ability to recognize mAb-coated cancer cells and activate immune effector cells. Lenalidomide is an immunomodulatory agent with the capacity to stimulate immune cell cytokine production and ADCC activity. This phase I trial evaluated the combination of cetuximab with lenalidomide for the treatment of advanced colorectal and head and neck squamous cell cancers (HNSCC). This trial included patients with advanced colorectal cancer or HNSCC. Treatment consisted of cetuximab 500 mg/m(2) i.v. every two weeks with lenalidomide given orally days 1-21 on a 28-day cycle. Three dose levels of lenalidomide were evaluated (15, 20, 25 mg). Correlative studies included measurement of ADCC, FcγRIIIA polymorphism genotyping, measurement of serum cytokine levels, and flow cytometric analysis of immune cell subtypes. Twenty-two patients were enrolled (19 colorectal cancer, 3 HNSCC). Fatigue was the only dose-limiting toxicity. One partial response was observed and 8 patients had stable disease at least 12 weeks. The recommended phase II dose is cetuximab 500 mg/m(2) with lenalidomide 25 mg daily, days 1-21. Correlative studies demonstrated a dose-dependent increase in natural killer cytotoxic activity with increasing doses of lenalidomide. Cetuximab and lenalidomide were well tolerated. There was a lenalidomide dose-dependent increase in ADCC with higher activity in patients enrolled in cohort 3 than those enrolled in cohorts 1/2. Although response was not a primary endpoint, there was evidence of antitumor activity for the combination therapy. Further investigation of lenalidomide as an immunomodulator in solid tumors is warranted. Mol Cancer Ther; 15(9); 2244-50. ©2016 AACR.

IL-21 Enhances Natural Killer Cell Response to Cetuximab-Coated Pancreatic Tumor Cells

PURPOSE

Alternative strategies to EGFR blockage by mAbs is necessary to improve the efficacy of therapy in patients with locally advanced or metastatic pancreatic cancer. One such strategy includes the use of NK cells to clear cetuximab-coated tumor cells, as need for novel therapeutic approaches to enhance the efficacy of cetuximab is evident. We show that IL-21 enhances NK cell-mediated effector functions against cetuximab-coated pancreatic tumor cells irrespective of KRAS mutation status.

EXPERIMENTAL DESIGN

NK cells from normal donors or donors with pancreatic cancer were used to assess ADCC, IFN-γ release, and T-cell chemotaxis toward human pancreatic cancer cell lines. The in vivo efficacy of IL-21 in combination with cetuximab was evaluated in a subcutaneous and intraperitoneal model of pancreatic cancer.

RESULTS

NK cell lysis of cetuximab-coated wild-type and mutant kras pancreatic cancer cell lines were significantly higher following NK cell IL-21 treatment. In response to cetuximab-coated pancreatic tumor cells, IL-21-treated NK cells secreted significantly higher levels of IFN-γ and chemokines, increased chemotaxis of T cells, and enhanced NK cell signal transduction via activation of ERK and STAT1. Treatment of mice bearing subcutaneous or intraperitoneal EGFR-positive pancreatic tumor xenografts with mIL-21 and cetuximab led to significant inhibition of tumor growth, a result further enhanced by the addition of gemcitabine.

CONCLUSIONS

These results suggest that cetuximab treatment in combination with IL-21 adjuvant therapy in patients with EGFR-positive pancreatic cancer results in significant NK cell activation, irrespective of KRAS mutation status, and may be a potential therapeutic strategy. Clin Cancer Res; 23(2); 489-502. ©2016 AACR.

Abstract 3093: 3D structural report of NRAS isoform 5

The protein NRAS is part of the NRAS-BRAF-MEK-ERK signaling cascade. Recently, 5 NRAS isoforms were discovered by our group, and it was observed that isoform 5 overexpression in vitro resulted in a more aggressive cell phenotype. NRAS isoform 5 increases phosphorylation of downstream targets (AKT, MEK, and ERK). The structural report is unavailable for NRAS isoform 5. In addition, it was found in the current study that the NRAS isoform 5 does not have GTPase activity due to lack the canonical GTP binding region. Given the importance of this pathway in driving melanoma progression, we studied the structural details of this novel NRAS isoform 5 by two biophysical techniques, NMR and CD spectroscopy.

The circular dichroism spectra of NRAS isoform 5 that was C-acetylated and N-amidated was measured using 11%, 14%, 21%, 45%, 56% and 85% trifluoroethanol (TFE) in a phosphate buffer. The secondary structural elements were induced at ∼14-15% TFE. There were no qualitative differences in the CD spectra between 56% and 85% TFE. Therefore 56% deuterated TFE was utilized in the NMR structural studies.

Two dimensional (2D) homonuclear and heteronuclear experiments were acquired at 25°C with Bruker Avance III HD 600 and 800 MHz NMR spectrometers (Campus Chemical Instrument Center NMR facility), each equipped with a triple resonance z axis gradient TXI cryoprobe for amino acid chemical shift assignments and structural determination of NRAS isoform 5. The NMR chemical shifts for the protons were assigned using traditional 2D TOCSY, COSY, and NOESY experiments. The 2D proton-carbon HSQC was utilized to facilitate the assignment of the alpha and side chain aliphatic protons. In the absence of TFE, there were no observable NOEs that could represent ordered secondary structures. Other than intra residue and short range sequential NOEs (i-j ≤ 2), only a weak medium range NOE was observed from the aromatic protons of Tyr 4 to the gamma proton of Val 7/8.

The secondary structure of NRAS isoform 5 was determined via the same NMR techniques in 56% TFE. The secondary structure was defined by 69 sequential NOEs and 39 medium range NOEs. NOEs characteristic of helical structure were observed in the NOESY spectra. For example, NOEs were measured from H(alpha, i) to H(beta, i+3) for residues Tyr 4, Lys 5, and Leu 6. The tertiary fold was determined by 10 key long-range NOEs. The flexible C terminal is brought in close proximity to the N-terminal helix by 4 NOEs between Val 8/9 and Val 14, and 5 NOEs between Tyr 4 and Try 20 to form a helix-turn-coil structure in presence of TFE. In addition, the proton chemical shifts for the aromatic proton chemical shifts for the tyrosine aromatic ring became distinct.

NRAS isoform 5 is highly flexible in aqueous solution, but forms a helix-turn-coil structure in the presence of trifluoroethanol as determined by NMR and CD spectroscopy. This data may be utilized as a starting point to understand the biophysical interactions of this novel NRAS isoform.

Citation Format: Joseph Markowitz, Tapas K. Mal, Chunhua Yuan, Nicholas B. Courtney, Mitra Patel, Andrew R. Stiff, James Blachly, Christopher Walker, Ann-Kathrin Eisfeld, Albert de la Chapelle, William E. Carson. 3D structural report of NRAS isoform 5. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3093.

Abstract 553: Ibrutinib, a BTK inhibitor, impairs the generation and function of myeloid derived suppressor cells

Myeloid derived suppressor cells (MDSC) interfere with anti tumor immune responses. MDSC have also been shown to antagonize the effectiveness of immune based therapies including immune checkpoint blockade. As a result, MDSC have received attention as potential targets for immune based combination therapies. There has been limited success in the identification of clinically active agents with the ability to inhibit the function or generation of MDSC. Ibrutinib is an orally available irreversible inhibitor of Bruton's tyrosine kinase (BTK) that is FDA approved for the treatment of B cell malignancies. In addition to B cells, cells of the myeloid lineage including monocytes and macrophages express BTK, and treatment with ibrutinib has been shown to alter their function and differentiation. As a result, it was hypothesized that ibrutinib would interfere with the function or generation of MDSC in the setting of cancer. MDSC isolated from the spleens of multiple murine tumor models (EMT6, 4T1, and C26) as well as MDSC from patients with metastatic melanoma expressed BTK. Treatment with ibrutinib at doses ranging from 0.1-5 μM inhibited the phosphorylation of BTK in both murine and human MDSC. Ibrutinib treatment of murine and human MDSC resulted in a significant reduction in nitric oxide (NO) production (p&lt; 0.05), but had only modest effects on MDSC levels of IDO and arginase. Ibrutinib was also able to inhibit murine MDSC migration in response to EMT6 cell line conditioned media and the chemokine CXCL12 (p&lt; 0.05). In addition, ibrutinib inhibited human MDSC migration in response to GM CSF (p&lt; 0.05). Ibrutinib reduced the expression of the myeloid adhesion molecules CD11a (p&lt; 0.05) and CD49D (p&lt; 0.01) by MDSC, which could explain the reduction in migration. Importantly, ibrutinib significantly reduced the ability of MDSC to suppress CD8+ T cell proliferation compared to DMSO (21.98% vs. 12.49% proliferation, p&lt; 0.05). Daily treatment with ibrutinib effectively inhibited the in vitro generation of human MDSC from monocytes by promoting HLA DR expression (p&lt; 0.05). Using the EMT6 mammary carcinoma model in vivo, ibrutinib treatment resulted in a significant reduction of MDSC in both the spleen and tumor (p&lt; 0.05). Ibrutinib also reduced the frequency of splenic MDSC in wild type B16F10 tumor bearing mice, but not in BTK mutant XID mice. In addition, both murine and human MDSC did not express significant levels of alternative ibrutinib targets including ITK, Bmx, and Blk. These results suggest that inhibition of BTK is the primary driver behind the observed effects of ibrutinib on MDSC function and generation. Finally, the combination of ibrutinib and anti PDL1 therapy was significantly more effective than either agent alone (p&lt; 0.01 and p&lt; 0.05) producing complete tumor regression in 50% of EMT6 tumor being mice. The results support further investigation of ibrutinib in combination with immune based therapies for solid tumors.

Citation Format: Andrew R. Stiff, Prashant Trikha, Robert Wesolowski, Kari Kendra, Sarvani Uppati, David Abood, Elizabeth McMichael, Megan Duggan, Amanda Campbell, Natarajan Muthusamy, Susheela Tridandapani, Michael Caliguiri, John C. Byrd, William E. Carson. Ibrutinib, a BTK inhibitor, impairs the generation and function of myeloid derived suppressor cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 553.

Abstract 195: Defining the role of PAK7 variants in melanoma

Melanoma mortality is directly linked to its profoundly metastatic nature and inherent resistance to conventional chemotherapy. For this reason, increased understanding of the molecular mechanisms driving melanoma progression is of utmost importance. The p21-activated serine/threonine kinases (PAKs) are frequently mutated or overexpressed in cancer and have recently been implicated in tumor metastasis, proliferation, and apoptotic resistance. This observation has inspired drug discovery efforts to limit PAK activity; yet, mechanistic understanding of how PAKs (especially Type II PAKs) contribute to tumor initiation and progression is still evolving. PAK7, a type II PAK, is mutated in 16-18% of all melanomas. Melanoma-associated PAK7 mutations occur throughout the gene and have unknown biochemical and physiological consequences. The objective of this study was to determine how tumor-associated PAK7 variants mechanistically contribute to melanoma initiation and progression. First, we characterized PAK7 protein expression in a panel of 39 melanoma cell lines and primary melanocyte cultures. PAK7 levels were similar in both tumorigenic and non-tumorigenic cells and failed to correlate with the status of common melanoma driver mutations (e.g. NRASQ61, BRAFV600). In an array of 101 human tumor biopsies, PAK7 expression did not significantly change with advancing melanoma stage; however, PAK7 levels were higher in regional lymph node biopsies when compared to primary skin lesions. Since mutation is the predominant mechanism affecting PAK7 in melanoma, we investigated the biochemical and physiological consequences of common PAK7 variants. 11 distinct PAK7 mutations were stably expressed at low levels in VMM39 (melanoma) and NCI-H441 (lung) cells. Using these clones, changes in the phosphorylation of downstream PAK7 targets associated with cellular migration (p120), proliferation (CRAF), and apoptotic resistance (BAD, MDM2) were examined. In addition, we defined phenotypic alterations in cellular morphology, proliferation, migration, and apoptotic resistance associated with the expression of each mutant. These data allowed us to classify PAK7 variants of unknown significance into groups associated with specific cellular outcomes. To our knowledge, this is the first study to functionally characterize a wide variety of melanoma-associated PAK7 mutations and represents a critical first step in understanding how this kinase contributes to tumor initiation and progression.

Citation Format: Kyle M. LaPak, Michael A. Gross, Denny C. Vroom, Greg B. Lesinski, William E. Carson. Defining the role of PAK7 variants in melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 195.

Trajectories of Stress, Depressive Symptoms, and Immunity in Cancer Survivors: Diagnosis to 5 Years

PURPOSE

Five-year disease endpoint trajectories are available for every cancer site. In contrast, there are few longitudinal, biobehavioral studies of survivors extending beyond the first or second year following diagnosis. This gap is addressed with stress, depressive symptom, and immunity data from breast cancer patients followed continuously for 5 years.

EXPERIMENTAL DESIGN

Women (N = 113) diagnosed and surgically treated for breast cancer and awaiting adjuvant therapy completed self-report measures of stress and depressive symptoms and provided blood for immune assays [natural killer cell cytotoxicity (NKCC) and T-cell blastogenesis]. Assessments (N = 12) were repeated every 4 to 6 months for 5 years.

RESULTS

Multiphase linear mixed models show phases of change and identified specific time points of change. Cancer stress shows two distinct phases of decline, with the change point being 12 months. In contrast, a steep decline in depressive symptoms occurs by 7 months, with stable, low levels thereafter. NKCC shows a steady upward trajectory through 18 months and upper limit stability thereafter, whereas there was no reliable trajectory for T-cell blastogenesis.

CONCLUSIONS

For the first time, trajectories and specific time points of change in biobehavioral data for breast cancer survivors are provided, traced through 5 years. Following diagnosis, the breast survivor experience is one of a co-occurrence of change (recovery) in psychologic and innate immunity markers from diagnosis to18 months, and a pattern of stability (depression, NKCC) or continued improvement (stress) through year 5. These data provide new directions for survivorship care and detail of the biobehavioral trajectory. Clin Cancer Res; 23(1); 52-61. ©2016 AACR.

A Critical Role for CD200R Signaling in Limiting the Growth and Metastasis of CD200+ Melanoma

CD200 is a cell surface glycoprotein that functions through engaging CD200R on cells of the myeloid lineage and inhibits their functions. Expression of CD200 was implicated in a variety of human cancer cells, including melanoma cells; however, its roles in tumor growth and immunity are not clearly understood. In this study, we used CD200R-deficient mice and the B16 tumor model to evaluate this issue. We found that CD200R-deficient mice exhibited accelerated growth of CD200(+), but not CD200(-), B16 tumors. Strikingly, CD200R-deficient mice receiving CD200(+) B16 cells i.v. exhibited massive tumor growth in multiple organs, including liver, lung, kidney, and peritoneal cavity, whereas the growth of the same tumors in wild-type mice was limited. CD200(+) tumors grown in CD200R-deficient mice contained higher numbers of CD11b(+)Ly6C(+) myeloid cells, exhibited increased expression of VEGF and HIF1α genes with increased angiogenesis, and showed significantly reduced infiltration of CD4(+) and CD8(+) T cells, presumably as the result of reduced expression of T cell chemokines, such as CXCL9 and CXCL16. The liver from CD200R-deficient mice, under metastatic growth of CD200(+) tumors, contained significantly increased numbers of CD11b(+)Gr1(-) myeloid cells and Foxp3(+) regulatory T cells and reduced numbers of NK cells. Liver T cells also had a reduced capacity to produce IFN-γ or TNF-α. Taken together, we revealed a critical role for CD200R signaling in limiting the growth and metastasis of CD200(+) tumors. Thus, targeting CD200R signaling may potentially interfere with the metastatic growth of CD200(+) tumors, like melanoma.

Global microRNA profiling for diagnostic appraisal of melanocytic Spitz tumors

BACKGROUND

Melanoma skin cancer remains the leading cause of skin cancer-related deaths. Spitz lesions represent a subset of melanocytic skin lesions characterized by epithelioid or spindled melanocytes organized in nests. These lesions occupy a spectrum ranging from benign Spitz and atypical Spitz lesions all the way to malignant Spitz tumors. Appropriate management is reliant on accurate diagnostic classification, yet this effort remains challenging using current light microscopic techniques. The discovery of novel biomarkers such as microRNAs (miR) may ultimately be a useful diagnostic adjunct for the evaluation of Spitz lesions. miR expression profiles have been suggested for non-Spitz melanomas but have yet to be ascribed to Spitz lesions. We hypothesized that distinct miR expression profiles would be associated with different lesions along the Spitz spectrum.

MATERIALS AND METHODS

RNAs extracted from paraffin-embedded, formalin-fixed tissues of 11 resected skin lesions including benign nevi (n = 2), benign Spitz lesions (n = 3), atypical Spitz lesions (n = 3), and malignant Spitz tumors (n = 3) were analyzed by the NanoString platform for simultaneous evaluation of over 800 miRs in each patient sample.

RESULTS

Benign Spitz lesions had increased expression of miR-21-5p and miR-363-3p compared with those of benign nevi. Malignant Spitz lesions exhibited overexpression of miR-21-5p, miR-155-5p, and miR-1283 relative to both benign nevi and benign Spitz tumors. Notably, atypical Spitz tumors had increased expression of miR-451a and decreased expression of miR-155-5p expression relative to malignant Spitz lesions. Conversely, atypical Spitz lesions had increased expression of miR-21-5p, miR-34a-5p, miR-451a, miR-1283, and miR-1260a relative to benign Spitz tumors.

CONCLUSIONS

Overall, distinct miR profiles are suggested among Spitz lesions of varying malignant potential with some similarities to non-Spitz melanoma tumors. This work demonstrates the feasibility of this analytic method and forms the basis for further validation studies.

NKp80 Defines a Critical Step during Human Natural Killer Cell Development

Human natural killer (NK) cells develop in secondary lymphoid tissues (SLTs) through distinct stages. We identified two SLT lineage (Lin)(-)CD34(-)CD117(+/-)CD94(+)CD16(-) "stage 4" subsets according to expression of the C-type lectin-like surface-activating receptor, NKp80: NKp80(-) (stage "4a") and NKp80(+) (stage "4b"). Whereas stage 4b cells expressed more of the transcription factors T-BET and EOMES, produced interferon-gamma, and were cytotoxic, stage 4a cells expressed more of the transcription factors RORγt and AHR and produced interleukin-22, similar to SLT Lin(-)CD34(-)CD117(+)CD94(-)CD16(-) "stage 3" cells, whose phenotype overlaps with that of group 3 innate lymphoid cells (ILC3s). Co-culture with dendritic cells or transplantation into immunodeficient mice produced mature NK cells from stage 3 and stage 4a populations. These data identify NKp80 as a marker of NK cell maturity in SLTs and support a model of human NK cell development through a stage 4a intermediate with ILC3-associated features.