Selected Tumor Types Research Articles

The future of radiotherapy in small animals – should the fractions be coarse or fine?

Radiation therapy has been used to treat animal cancers for more than 100 years. Clinical experiences and experimental results have been widely published and provide a basis for the recognition of radiation therapy as an integral component of multimodal cancer management in veterinary oncology. As the expectations of pet owners and the demand for treatment of companion animals with cancer have increased, veterinary oncology itself has undergone dramatic advances in the past several decades both in terms of improved diagnostics and treatments, including increased accessibility of radiation therapy. Synchronous with development of the specialism of veterinary radiation oncology, confusion and controversy have arisen with regard to distinguishing between different types of radiotherapy and methods of treatment delivery. Importantly, the confusion extends beyond semantics, and includes opinionated debate about defining which forms of therapy (if any at all) are optimal for a given patient. This exemplifies how, despite marks of maturity including age and a robust publication history, the field of veterinary radiation oncology is in some ways still in its infancy. The purpose of this article is to review the evidence base for daily (fine) fractionation versus weekly (coarse) hypofractionation in veterinary oncology, using selected tumour types as examples.

Abstract 182: Superior targeting of tumor-stromal interactions and endothelial migration with a bispecific antibody to α5 and αv integrins

Abstract Introduction: The integrin α5β1 has been implicated in the adhesive and migratory response of prostate cancer cells induced by fibronectin fragments secreted by human bone-marrow derived mesenchymal stromal cells (hBM-MSCs) [Joshi, Cell Adh and Migr 2016). Genetic inactivation of integrin α5 in PC-3 cells downregulated the bcl-2 family of proteins and induced programmed cell death (Ren, Mol Cell Res 2017) - linking hBM-MSCs to a putative bone marrow niche survival program for prostate cancer cells. We hypothesized that the fibronectin-binding integrins α5β1 and integrin αv collaborate in broader tumor-stromal interactions and sought to examine the impact of combinatorial inactivation of these integrins. Methods: Monospecific antibodies to α5 (or its obligate α5β1 heterodimer) and to integrin alpha v (or the αvβ3 heterodimer) were utilized to assess the efficacy of a combinatorial neutralization approach over either single agent in α5/αv co-expressing cells from diverse tumor types including prostate, breast, glioma, cervix and uterine cancer. Assays included adhesion, migration, cell survival and the induction of endothelial migration in co-culture with stromal cells. To address the hypothesis that a bispecific integrin targeting antibody would be superior to a combinatorial approach with monospecific integrin antibodies, a bispecific antibody prototype that simultaneously targets the α5β1 and αv integrins [Bsα5β1/αvAb] was constructed and deployed in comparative assays. Results: Combined α5 and av neutralization with dual monospecific antibodies was superior to individual single agents in blocking adhesion, migration and the induction of endothelial chemotaxis across diverse tumor types that co-expressed α5 and αv integrins. However, a significant superiority of the Bsα5β1/αvAb was noted over the combinatorial approach with monospecific antibodies in these assays. In addition, a significant reduction in cell survival was noted in selected tumor types with the Bsα5β1/αvAb. Strikingly, the Bsα5β1/αvAb was significantly more potent than bevacizumab in the inhibition of endothelial migration induced by tumor-stromal cell interactions Conclusions: Combinatorial α5 and av integrin targeting in tumor cells that co-express α5 and av integrins effectively abrogates tumor-stromal interactions and the resultant endothelial migratory response. A Bsα5β1/αvAb demonstrates a significant improvement over combinatorial monospecific antibodies likely through diverse mechanisms including cross-priming. Targeting tumor, stromal and endothelial cells simultaneously with a Bsα5β1/αvAb approach represents a potentially effective therapeutic strategy for targeting diverse mechanisms of progressive disease in the tumor microenvironment. Citation Format: Raghav Joshi, Wenying Ren, Paul Mathew. Superior targeting of tumor-stromal interactions and endothelial migration with a bispecific antibody to α5 and αv integrins [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 182.

Abstract CT126: A phase I first time in human study to evaluate the safety, pharmacokinetics, and immunogenicity of MEDI5083 alone and in combination with durvalumab in selected advanced solid tumors

Abstract Background CD40 is a member of the TNFR superfamily that is broadly expressed by immune, vascular, epithelial, and tumor cells. Interaction between CD40 and its ligand CD40L plays an important role in innate and adaptive immunity. APCs such as dendritic cells can be primed by CD4+ T cells by interaction between CD40 and CD40L. Several studies have confirmed that CD40 is broadly expressed on multiple solid tumor types. Thus, further evaluation of investigational agents and combination immunotherapies targeting the CD40 pathway is warranted across multiple cancer indications. MEDI5083 is a homodimeric fusion protein consisting of 3 scCD40L domains and an IgG4P Fc domain. MEDI5083 agonizes CD40 on APCs and bridges the innate and adaptive immune systems by promoting potent antitumor T cell mediated immune responses. Durvalumab is a selective, high-affinity, engineered human IgG1 mAb that blocks PD-L1 binding to PD-1 and CD80, allowing T cells to recognize and kill tumor cells. In clinical studies durvalumab has shown a manageable and consistent tolerability profile across multiple tumor types. The combination of MEDI5083 and durvalumab has the potential to activate the adaptive immune system through potentially complementary mechanisms, leading to enhanced targeting of tumor cells. Methods This Phase 1 first in human study evaluates the safety, pharmacokinetics, and immunogenicity of MEDI5083 alone and in combination with durvalumab in select advanced solid tumors. The primary objective is to evaluate the safety and tolerability, describe dose-limiting toxicity, and determine the maximum tolerated dose or the highest protocol-defined dose for MEDI5083 when administered as monotherapy and when administered concurrently in combination with durvalumab. Key secondary objectives include describing PK, systemic pharmacodynamics, immunogenicity and preliminary clinical activity of MEDI5083 administered alone or concurrently with durvalumab. This is a 3-part study; Part 1 is dose escalation of MEDI5083 monotherapy followed by either durvalumab monotherapy or potential reinduction with MEDI5083. Part 2 is dose escalation of MEDI5083 with concurrent durvalumab therapy, followed by durvalumab monotherapy restricted to selected tumor types. Part 3 is MEDI5083 with concurrent durvalumab, followed by durvalumab monotherapy in tumor specific expansion cohorts. Recruitment is ongoing (NCT03089645). Citation Format: Ben Tran, Johanna Bendell, Martin Gutierrez, Jie Yang, Natasha Angra, Victoria L. Chiou, Mark Voskoboynik. A phase I first time in human study to evaluate the safety, pharmacokinetics, and immunogenicity of MEDI5083 alone and in combination with durvalumab in selected advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT126.

Defining Survivorship Trajectories Across Patients With Solid Tumors

Survivorship involves a multidisciplinary approach to surveillance and management of comorbidities and secondary cancers, overseen by oncologists, surgeons, and primary care physicians. Optimal timing and coordination of care, however, is unclear and often based on arbitrary 5-year cutoffs. To determine high- and low-risk periods for all tumor types that could define when survivorship care might best be overseen by oncologists and when to transition to primary care physicians. In this pan-cancer, longitudinal, observational study, excess mortality hazard, calculated as an annualized mortality risk above a baseline population, was plotted over time. The time this hazard took to stabilize defined a high-risk period. The percent morality elevation above age- and sex-matched controls in the latter low-risk period was reported as a mortality gap. The US population-based Surveillance, Epidemiology, and End Results database defined the cancer population, and the US Census life tables defined controls. Incident cases of patients with cancer were separated into tumor types based on International Classification of Diseases for Oncology definitions. Population-level data on incident cancer cases was compared with the general US population. Overall mortality and cause of death were reported on observed cancer cases. A total of 2 317 185 patients (median age, 63 years; 49.8% female) with 66 primary tumor types were evaluated. High-risk surveillance period durations ranged from less than 1 year (breast, prostate, lip, ocular, and parathyroid cancers) up to 19 years (unspecified gastrointestinal cancers). The annualized mortality gap, representing the excess mortality in the stable period, ranged from a median 0.26% to 9.33% excess annual mortality (thyroid and hypopharyngeal cancer populations, respectively). Cluster analysis produced 6 risk cluster groups: group 1, with median survival of 16.2 (5th to 95th percentile range [PR], 10.7-40.2) years and median high-risk period of 2.5 (PR, 0-5.0) years; group 2, 8.3 (PR, 5.1-23.3) and 2.5 (PR, 4.0-8.0) years; group 3, 2.8 (PR, 1.4-3.7) and 7.0 (PR, 6.0-11.1) years; group 4, 1.6 (PR, 1.5-1.8) and 6.0 (PR, 5.1-11.4) years; group 5, 0.8 (PR, 0.5-1.2) and 0.8 (PR, 0.5-1.2) years; and group 6, 0.5 (PR, 0.4-0.8) and 12.0 (PR, 9.3-12.9) years, respectively. Subanalyses of selected tumor types in these groups revealed that stratifying on stage and histologic type can change the risk cluster and guidance for care. These findings indicate that a standardized 5-year surveillance period is inadequate for some cancers while excessive for others. High-risk cancers require the most resources with the longest high-risk period, highest persistent baseline mortality risk, and longest period of primary cancer mortality, all arguing for longer follow-up with an oncologist in these cancers.

PanCancer insights from The Cancer Genome Atlas: the pathologist's perspective.

The Cancer Genome Atlas (TCGA) represents one of several international consortia dedicated to performing comprehensive genomic and epigenomic analyses of selected tumour types to advance our understanding of disease and provide an open-access resource for worldwide cancer research. Thirty-three tumour types (selected by histology or tissue of origin, to include both common and rare diseases), comprising >11 000 specimens, were subjected to DNA sequencing, copy number and methylation analysis, and transcriptomic, proteomic and histological evaluation. Each cancer type was analysed individually to identify tissue-specific alterations, and make correlations across different molecular platforms. The final dataset was then normalized and combined for the PanCancer Initiative, which seeks to identify commonalities across different cancer types or cells of origin/lineage, or within anatomically or morphologically related groups. An important resource generated along with the rich molecular studies is an extensive digital pathology slide archive, composed of frozen section tissue directly related to the tissues analysed as part of TCGA, and representative formalin-fixed paraffin-embedded, haematoxylin and eosin (H&E)-stained diagnostic slides. These H&E image resources have primarily been used to verify diagnoses and histological subtypes with some limited extraction of standard pathological variables such as mitotic activity, grade, and lymphocytic infiltrates. Largely overlooked is the richness of these scanned images for more sophisticated feature extraction approaches coupled with machine learning, and ultimately correlation with molecular features and clinical endpoints. Here, we document initial attempts to exploit TCGA imaging archives, and describe some of the tools, and the rapidly evolving image analysis/feature extraction landscape. Our hope is to inform, and ultimately inspire and challenge, the pathology and cancer research communities to exploit these imaging resources so that the full potential of this integral platform of TCGA can be used to complement and enhance the insightful integrated analyses from the genomic and epigenomic platforms. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

IL10 Release upon PD-1 Blockade Sustains Immunosuppression in Ovarian Cancer.

Ligation of programmed cell death-1 (PD-1) in the tumor microenvironment is known to inhibit effective adaptive antitumor immunity. Blockade of PD-1 in humans has resulted in impressive, durable regression responses in select tumor types. However, durable responses have been elusive in ovarian cancer patients. PD-1 was recently shown to be expressed on and thereby impair the functions of tumor-infiltrating murine and human myeloid dendritic cells (TIDC) in ovarian cancer. In the present work, we characterize the regulation of PD-1 expression and the effects of PD-1 blockade on TIDC. Treatment of TIDC and bone marrow-derived dendritic cells (DC) with IL10 led to increased PD-1 expression. Both groups of DCs also responded to PD-1 blockade by increasing production of IL10. Similarly, treatment of ovarian tumor-bearing mice with PD-1 blocking antibody resulted in an increase in IL10 levels in both serum and ascites. While PD-1 blockade or IL10 neutralization as monotherapies were inefficient, combination of these two led to improved survival and delayed tumor growth; this was accompanied by augmented antitumor T- and B-cell responses and decreased infiltration of immunosuppressive MDSC. Taken together, our findings implicate compensatory release of IL10 as one of the adaptive resistance mechanisms that undermine the efficacy of anti-PD-1 (or anti-PD-L1) monotherapies and prompt further studies aimed at identifying such resistance mechanisms. Cancer Res; 77(23); 6667-78. ©2017 AACR.

Abstract 3664: CDX-1402, a dendritic cell targeted fusion protein designed to elicit immunity to mesothelin and HER2 expressing tumors

Abstract The use of mAbs to target antigens to the endocytic receptor Dec205 on dendritic cells (DC) is an effective means to elicit helper and cytolytic T cell responses in the presence of appropriate adjuvants to activate DC. We have translated this concept to clinical studies using a fully human Dec205-specific mAb genetically altered to include the entire NY-ESO-1 cancer antigen (CDX-1401), which when combined with TLR agonists results in effective stimulation of both cellular and humoral NY-ESO-1-specific responses in cancer patients (Dhodapkar MV et al., Sci. Transl. Med. 6:232-251, 2014). Building on this concept, we developed a new fusion protein in which the Dec205 mAb is engineered to carry two tumor-related antigens in tandem [ECDs of mesothelin (MSLN) and HER2]. HER2 and MSLN are broadly expressed in selected tumor types and provide an expanded opportunity for this immunotherapy approach. We previously generated an anti-mouse DC-targeted HER2 vaccine (αDec205-HER2) and a MSLN vaccine (αDec205-MSLN) and demonstrated in mouse studies that they were potent in eliciting strong and broad CD4 T cell immunity, cross priming of CD8 T cells and humoral responses specific for HER2 or MSLN antigens, respectively. In this work we tested the impact of expressing two tumor antigens in the same construct on the immune responses to each antigen. Mice of various genetic backgrounds were immunized with equimolar amount of αDec205-HER2 (6.8 μg), αDec205-MSLN (5 μg) or αDec205-MSLN-HER2 (8.3 μg) in combination with poly IC-LC plus anti-CD40 or anti-CD27 as adjuvant. Similar levels of CD4 and CD8 T cell responses upon single or dual antigen vaccination were observed in the assessment of intracellular cytokines and IFNγ-ELISPOT after ex vivo stimulation with peptide pools derived from either HER2 or MSLN. High titers of anti-HER2 and anti-MSLN IgG, including IgG1 and IgG2a, were elicited upon αDec205-MSLN-HER2 vaccination. Both humoral and cellular responses were boosted by multiple dosing of the vaccine. Based on these data we developed CDX-1402 using our anti-human Dec205 mAb genetically fused to MSLN and HER2. CDX-1402 was shown to effectively deliver these antigens to human DC in vitro for activation of antigen-specific T cells. In vitro stimulation of healthy volunteer circulating T cells with autologous DC treated with CDX-1402 plus TLR agonist resulted in T cell cultures that produced IFNγ only when presented with CDX-1402-treated DCs or DC loaded with a select panel of HLA-I/II synthetic peptides derived from either MSLN or HER2 but not with control peptides. We also observed that T cells sensitized to CDX-1402 recognize cancer cell lines that express the vaccine antigen and HLA. Altogether, the data lend support for the use of CDX-1402 as a novel immunotherapeutic for treatment of multiple cancer types expressing MSLN and/or HER2. Citation Format: Li-Zhen He, Jenifer Widger, James Testa, Laura Mills-Chen, Biwei Zhao, Jeff Weidlick, Crystal Sisson, Anna Wasiuk, Laura Vitale, Joel Goldstein, Henry Marsh, Tibor Keler, Venky Ramakrishna. CDX-1402, a dendritic cell targeted fusion protein designed to elicit immunity to mesothelin and HER2 expressing tumors [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 3664. doi:10.1158/1538-7445.AM2017-3664

Abstract CT038: A phase I, open-label, dose-escalation study to investigate the safety, pharmacokinetics, pharmacodynamics, and clinical activity of GSK3326595 in subjects with solid tumors and non-Hodgkin's lymphoma

Abstract Background Protein arginine methyltransferase 5 (PRMT5) is the primary enzyme responsible for symmetric arginine dimethylation of multiple proteins that impact cell proliferation. Its substrates include histones and proteins involved in signal transduction, gene transcription, DNA repair, and mRNA splicing. PRMT5 overexpression occurs in a number of different cancers, and higher expression is correlated with poor prognosis. Additional published data implicates PRMT5 in tumorigenesis, and as such it represents a novel target for therapeutic intervention in oncology. GSK3326595 is a potent, specific, and reversible inhibitor of PRMT5 that inhibits proliferation and induces cell death in a broad range of solid and hematologic tumor cell lines. It also exhibits potent antitumor activity in vivo in animal models. Methods Study 204653 is a Phase I, two-part, open-label, dose escalation/expansion study assessing the safety and tolerability of GSK3326595 in adult subjects with relapsed/refractory solid tumors and non-Hodgkin’s lymphoma. Dose escalation is being performed in subjects with solid tumors of any histology. An accelerated dose titration is employed with one subject per dose level until the occurrence of a ≥ Grade 2 non-disease related toxicity. Thereafter, subjects are enrolled in cohorts of approximately 3, and a modified toxicity probability interval (mTPI) method is used to guide dose escalation decisions. Dose escalation continues until the maximum tolerated dose (MTD) is identified. All data, including safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and clinical activity, will be used to identify a recommended Phase 2 dose (RP2D). In Part 1, approximately 42 subjects are to be enrolled (30 subjects in dose escalation and an additional 12 subjects at or about the MTD to collect additional data, including PD and metabolites); no hypothesis will be tested, and all analysis will be descriptive and exploratory. In Part 2, the clinical activity of GSK3326595 will be evaluated in expansion cohorts of subjects with select tumor types. Based on preclinical data, enrollment is initially limited to subjects with triple-negative breast cancer (TNBC), metastatic bladder cancer (mBC), glioblastoma multiforme (GBM), and non-Hodgkin’s lymphoma (NHL); additional cohorts may be added based on emerging preclinical and clinical data. Two cohorts of NHL are scheduled, allocated by TP53 wild type versus mutant status. Up to 138 subjects may be enrolled in Part 2, and cohorts may be closed early for futility. As of 17 January 2017, recruitment is ongoing across four centers (USA, Canada, Netherlands, and France), and four subjects have been enrolled into the dose-escalation cohorts. ClinicalTrials.gov identifier: NCT02783300 Study is funded by GlaxoSmithKline Citation Format: Drew Rasco, Anthony Tolcher, Lillian L. Siu, Kimberley Heinhuis, Sophie Postel-Vinay, Olena Barbash, Jacqueline L. Egger, Shelby Gorman, Thierry Horner, Arindam Dhar, Brandon E. Kremer. A phase I, open-label, dose-escalation study to investigate the safety, pharmacokinetics, pharmacodynamics, and clinical activity of GSK3326595 in subjects with solid tumors and non-Hodgkin's lymphoma [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 CT038. doi:10.1158/1538-7445.AM2017-CT038

Molecular Aspects of Thyroid Tumors with Emphasis on MicroRNA and Their Clinical Implications

Central to neoplastic transformation and tumor progression is alteration of the signaling pathways that control cell proliferation and apoptosis. The key mechanisms for this neoplastic process are genetic changes (mutations of cancer-related genes) and recently identified epigenetic changes that involve DNA methylation, chromatin remodeling (which has a profound effect on the control of gene expression), and noncoding, regulatory RNA (notably, microRNA - miRNA). MiRNAs control expression of their target gene post-transcriptionally. These molecular factors have potential as diagnostic, prognostic, and predictive molecular markers. Epithelial tumors of the thyroid gland are a histogenetically, morphologically, and pathobiologically heterogeneous group of neoplasms and require new, molecular approaches in clinical practice. This review aims to present contemporary scientific knowledge of this molecular (genetic and epigenetic) field of sporadic thyroid tumors of follicular cell origin and their potential clinical implications. The fundamental mutations (BRAFV600E, RET/PTC, RAS, and PAX8-PPARG) in selected tumor types are described comprehensively. Special attention is paid to miRNAs, including their biogenesis, function, and expression profiles in the most common thyroid tumors - follicular adenoma, follicular carcinoma, and papillary carcinoma. Thyroid cancer medicine has recently entered a new, molecular era. Comprehensive knowledge of all molecular aspects may improve diagnostics and management of thyroid neoplasms through the introduction of novel, progressive treatment strategies for this cancer. Further research on signaling pathway-related targets, standardization of methods, and evaluation of results are required.Key words: thyroid tumors - cancerogenesis - genetics - epigenetics - microRNA The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 19. 10. 2016Accepted: 2. 11. 2016.

A phase Ib dose escalation study of combined inhibition of IDO1 (GDC-0919) and PD-L1 (atezolizumab) in patients (pts) with locally advanced or metastatic solid tumors.

105 Background: GDC-0919, a small molecule inhibitor of indoleamine-2,3-dioxygenase 1 (IDO1), reduces tryptophan catabolism and kynurenine production within the tumor microenvironment that may promote normal effector T cell activity and an immunogenic state. IDO1 inhibition may complement targeting of PD-L1 with atezolizumab. Methods: A Phase Ib, open-label, study assessed safety, pharmacokinetics (PK), pharmacodynamics (PD), and anti-tumor activity (RECIST v1.1) of GDC-0919 and atezolizumab in pts with locally advanced or metastatic solid tumors. Pts were given escalating doses of GDC-0919 (50-1000 mg orally twice daily, for 21 days) and atezolizumab (1200 mg IV, every 3 weeks) using a standard 3+3 design. Results: As of 14Dec2016, 52 pts were treated in 6 cohorts of GDC-0919 plus atezolizumab. The median number of prior systemic therapies was 3 (range 1-9); 2 pts received prior immunotherapy. Pts received a median of 4 cycles of GDC-0919 and atezolizumab (range 1-17). No MTD was identified. Across all dose levels, 1 DLT was observed (Grade [G] 3 sepsis syndrome at GDC-0919 200 mg); no G4/5 AEs were attributed to study treatment. G3+ AEs, regardless of causality were reported in 34 (65%) pts. Related G3 AEs were reported in 7 (13%) pts, included nausea, rash, sepsis syndrome, fatigue, and pneumonitis. Two pts (4%) had AEs leading to treatment discontinuation, related in 1/2 (G3 pneumonitis). Combination PK was consistent with single agent observations and supports BID dosing of GDC-0919. Peripheral PD showed dose-dependent decreases in plasma kynurenine, consistent with systemic modulation of IDO1. Preliminary efficacy data from 45 pts with ≥ 1 on-treatment tumor assessments included 4 patients (9%) with partial response and 11 (24%) pts with stable disease. Conclusions: The combination of GDC-0919 and atezolizumab was generally well-tolerated and demonstrated peripheral IDO1 modulation and preliminary efficacy in a heterogeneous patient population during dose escalation. The study is currently enrolling pts with select tumor types in expansion cohorts to assess tumor PD and combination efficacy. Clinical trial information: NCT02471846.

Phase 1 trial of CA-170, a novel oral small molecule dual inhibitor of immune checkpoints PD-1 and VISTA, in patients (pts) with advanced solid tumor or lymphomas.

TPS3099 Background: Programmed-death 1 (PD-1) and V-domain Ig suppressor of T-cell activation (VISTA) are independent immune checkpoints that negatively regulate T-cell function and are implicated in various malignancies. Preclinical studies have demonstrated that dual blockade of these pathways is synergistic. CA-170 is a first-in-class oral small molecule that directly targets both PD-1/PD-L1 and VISTA pathways and has shown anti-tumor activity in multiple preclinical models. Methods: The dose escalation phase has a target enrollment of 50 pts with advanced solid tumors or lymphomas onto escalating doses; the first four single-pt cohorts are accelerated titration but then switch to 3+3 design. The dose expansion phase has a target enrollment of 250 pts with select tumor types known to be responsive to anti-PD-1/L1 inhibitors and/or known to express PD-L1 or VISTA. Key eligibility criteria include: age ≥ 18 years, ECOG ≤1, adequate organ function, and ineligible for/did not respond to standard therapy including anti-PD-1/L1 inhibitors, where available. Primary objectives of this first-in-human study: safety, maximum tolerated dose, and recommended phase 2 dose. Secondary objectives: pharmacokinetics (PK) and anti-tumor activity. Exploratory endpoints: biomarkers and pharmacodynamic (PD) effects, which include changes in immune cell and peripheral cytokine populations in tumor (IHC/mRNA) and blood (flow cytometry/mRNA). Oral CA-170 is administered once daily in 21-day cycles. Response will be evaluated every other cycle per RECIST (v1.1) and Immune-related Response Criteria or by Cheson criteria (2007). Patients who discontinue treatment for reasons other than progressive disease will be followed for progression-free survival. Serial plasma, blood, and tumor samples will be collected for PK and PD evaluation. Clinical trial identifier: Clinical trial information: NCT02812875.

Epacadostat plus nivolumab in patients with advanced solid tumors: Preliminary phase I/II results of ECHO-204.

3003 Background: ECHO-204 is an ongoing, open-label, phase 1/2 (P1/2) study of epacadostat (E; potent and selective oral inhibitor of the immunosuppressive enzyme indoleamine 2,3-dioxygenase 1) plus PD-1 inhibitor nivolumab (N) in patients (pts) with advanced cancers (NSCLC, MEL, OVC, CRC, SCCHN, B-cell NHL [including DLBCL], GBM). Preliminary P1/2 safety and tolerability outcomes for the overall study population and P2 response for select tumor types (SCCHN, MEL, OVC, CRC) are reported. Methods: In P1 dose escalation, pts received E (25, 50, 100, 300 mg BID) + N (3 mg/kg Q2W); in P2 cohort expansion, pts received E (100 or 300 mg BID) + N (240 mg Q2W). Safety/tolerability was assessed in pts receiving ≥1 E + N dose. Response was assessed in RECIST v1.1 evaluable pts; for recently enrolled pt subgroups, only preliminary DCR (CR+PR+SD) is presented. Results: As of 29OCT2016,241 pts (P1, n = 36; P2, n = 205) were enrolled. No DLT was observed in P1. Most common TRAEs (≥15%) in pts treated with E 100 mg (n = 70) and E 300 mg (n = 135) were rash (33% and 22%, respectively), fatigue (26% and 31%), and nausea (24% and 19%). Rash was the most common grade ≥3 TRAE in E 100 mg and E 300 mg subgroups (10% and 12%). TRAEs led to discontinuation in 7% (E 100 mg) and 13% (E 300 mg) of pts. There were no TR-deaths. For the 23 recently enrolled, efficacy-evaluable SCCHN pts treated with E 300 mg, preliminary DCR was 70% (n = 16). Of 30 MEL pts, 8 were treated with E 100 mg and 22 were more recently enrolled and treated with E 300 mg. ORR (CR+PR) and DCR in MEL pts treated with E 100 mg were 75% (n = 6; all PR) and 100% (n = 8; 2 SD), respectively. Preliminary DCR in MEL pts treated with E 300 mg was 64% (n = 14). Of 29 OVC pts, 18 were treated with E 100 mg and 11 with E 300 mg.ORR and DCR for OVC pts treated with E 100 mg were 11% (n = 2; 2 PR) and 28% (n = 5; 3 SD); for 11 OVC pts treated with E 300 mg, ORR and DCR were 18% (n = 2; 2 PR) and 36% (n = 4; 2 SD).For 25 CRC pts (all E 100 mg), ORR and DCR were 4% (n = 1; PR) and 24% (n = 6; 5 SD).Safety/efficacy evaluations are ongoing for all cohorts. Conclusions: E + N was generally well tolerated up to the maximum E 300-mg dose. P2 ORR/DCR outcomes are promising, particularly in SCCHN and MEL pts. Updated data will be presented at the meeting. Clinical trial information: NCT02327078.

Mesenchymal stromal cells producing TNFα lack inhibitory effect against A375 experimental lung metastases.

Cell-based anticancer therapy using mesenchymal stromal cells (MSCs) engineered to express therapeutic genes has apotential to target the cancer cells in vivo. Metastatic dissemination of melanoma remains aserious problem in the treatment. In our previous work we used MSCs overexpressing gene for tumor necrosis factor α(TNFα; MSCs/TNFα), and we achieved inhibition of melanoma xenograft growth when engineered MCSs/TNFα were coinjected with tumor cells subcutaneously. The TNFα as apleiotropic cytokine induces apoptosis of tumor cells, creates "tumor resistant" microenvironment, enhances immune response and can have tumor destructive capacity in selected tumor types, especially in tumors of mesodermal origin.In this study we investigated the possibility of intravenously administered MCSs/TNFα to inhibit metastatic spread of A375 melanoma cells in the lungs. We confirmed elevated expression of TNFα transgene in the lung tissue 20 days after MCSs/TNFα intravenous infusion. We also documented that constitutive expression of TNFα transgene is able to neutralize the supportive effect of MSCs on melanoma cells growth. Metastatic spread of A375 melanoma cells in the lung was inhibited approximately to 50% after MCSs/TNFα i.v. administration in comparison to control group with parental MSCs supporting tumor growth. In conclusion, engineered MCSs/TNFα administered intravenously did not demonstrate significant antitumor effect against experimental melanoma lung metastases in this model settings.

Advancing Treatment of Pituitary Adenomas through Targeted Molecular Therapies: The Acromegaly and Cushing Disease Paradigms

The current treatment of pituitary adenomas requires a balance of conservative management, surgical resection, and in select tumor types, molecular therapy. Acromegaly treatment is an evolving field where our understanding of molecular targets and drug therapies has improved treatment options for patients with excess growth hormone levels. We highlight the use of molecular therapies in this disease process and advances in this field, which may represent a paradigm shift for the future of pituitary adenoma treatment.

Abstract 1249: PRN1371, an irreversible, covalent inhibitor of FGFR1, 2, 3 and 4 is highly efficacious in preclinical tumor models

Abstract Introduction: Multiple human cancers harbor alterations in FGFRs that drive tumor growth, including mutations, translocations and amplifications. We developed a covalent, irreversible, highly selective FGFR1, 2, 3 and 4 inhibitor, PRN1371, by targeting a cysteine residue within the kinase domain. This approach enables highly selective and sustained inhibition of FGFR which extends well beyond circulating drug concentrations. PRN1371 is currently in a phase 1 clinical trial for the treatment of solid tumors. Materials and Methods: FGFR1-4 enzymatic activities were measured using the Caliper microfluidics Labchip system. Inhibition of proliferation was assessed over 3 days using Cell-Titer-Glo. SNU16 and RT4 xenograft tumor models were used to investigate pharmacodynamics and efficacy. For tumor inoculation, cancer cells were implanted into the rear flank of immunocompromised mice. Once tumor volume reached a mean average of 175mm3, mice were randomized and treated with FGFR inhibitor. Results: PRN1371 is a novel investigative drug that is a potent ATP competitive, highly selective inhibitor of the FGFR family of protein kinases. PRN1371 binds irreversibly to FGFR1, 2, 3 and 4, leading to long duration of target inhibition. The IC50 values for FGFR1, 2, 3 and 4 are 0.7, 1.3, 4.1 and 19.2 nM, respectively. The IC50 values are 55.0, 12.0, 1.2 and 2.3 nM for FGFR3-V555M, FGFR2-N549H, FGFR3-G697C and FGFR3-K650E, respectively. PRN1371 exhibited no significant activity against 247 other protein kinases. PRN1371 demonstrates potent inhibition of cell proliferation in multiple tumor cell lines driven by dysregulated FGFR signaling. In RT4, RT112, SNU16, AN3-CA, LI7, JHH7, and OPM2 cells, EC50's are 4.0, 4.1, 2.6, 43.3, 33.1, 231 and 14.0 nM, respectively. PRN1371 is rapidly and well-absorbed. Bioavailability is dose and species-dependent. PRN1371 demonstrates potent tumor growth inhibition and regression in FGFR3-fusion expressing RT4 and FGFR2-amplified SNU16 xenograft models, when dosed either continuously, or intermittently, and is generally well-tolerated. PRN1371 is also shown to have significant anti-tumor activity against a panel of PDX tumor xenografts of various lineages harboring different FGFR pathway alterations. The phase 1 clinical trial will evaluate ascending doses of PRN1371 in a conventional “three plus three” design. Expansion cohorts of selected tumor types will then be investigated at the recommended dose level. Conclusion: PRN1371 is a potent, highly selective, irreversible inhibitor exhibiting sustained inhibition of FGFR 1, 2, 3 and 4. A Phase 1 clinical trial of PRN1371 for the treatment of solid tumors is currently ongoing. Citation Format: Eleni Venetsanakos, Michael Bradshaw, David M. Goldstein, Kwan Leung, Dane Karr, Yan Xing, Jacob LaStant, Philip Nunn, Jin Shu, Abha Bommireddi, Steven G. Gourlay, Jens Oliver Funk, Ken A. Brameld. PRN1371, an irreversible, covalent inhibitor of FGFR1, 2, 3 and 4 is highly efficacious in preclinical tumor models. [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 1249.

Abstract P6-01-05: Radiological evaluation of neo-adjuvant endocrine therapy in hormone-receptor positive early breast cancer

Abstract Recently, there is increased attention to neo-adjuvant endocrine therapy in breast cancer. Especially for selected tumour types and fragile elderly patients this might be a promising alternative to chemotherapy. Monitoring treatment effect during neo-adjuvant endocrine therapy is crucial to allow a timely switch to chemotherapy in case of a non-successful treatment. Most trials evaluating neo-adjuvant endocrine therapy use palpation as primary outcome and multiple radiological modalities as secondary outcomes. The aim of this study was to determine which evaluation corresponds best to pathological resection size after 6 months of neo-adjuvant endocrine therapy. This analysis was conducted in the TEAM-IIA trial in which 102 patients with early breast cancer (>2 cm and >50% ER expression) were treated with neo-adjuvant exemestane. In total, 83 patients were treated for 6 months and 19 for 3 months. Therapy response evaluation was performed using repeated palpation (mostly by the same clinician), mammography, ultrasound and MRI. Only measurements within 2 months before surgery were considered. After surgery, the size of the remaining tumour was reported and used as reference. In total, 93 resection size measurements were available. From the 93 patients for whom resection size was available, 69 patients were evaluated by palpation, 53 by ultrasound, 42 by mammography and 29 by MRI. Overall, palpation showed to be the most reliable predictor for resection size (correlation of 49%), followed by mammography (31%), ultrasound (14%) and MRI (1%). Mammography showed the smallest mean absolute error (MAE, 8.7 mm), followed by ultrasound (9.2 mm), palpation (11.4 mm) and MRI (12.3 mm). The low correlation of MRI with resection size was mostly due to a relative high number of radiological complete remissions (14%, n=4), of which only one was a true pathological complete response (pCR), while the other tumours were up to 80 mm at resection. Although of less influence on the correlation to resection size, false complete remissions were observed in all other modalities. Time to surgery was an important factor for all modalities. After correcting for non-predictive radiological complete responses and limiting the measurements to one month before surgery, all correlations increased significantly (mammography=72%, palpation=70%, ultrasound=58%, MRI=50%) with a concomitant decrease in mean absolute error. The low correlation of MRI with resection size was mostly due to non-visible measurements, interpreted as radiological complete remissions of which only one in four was a true pathological complete response (pCR) while the other tumours were 25, 65, and 80 mm at resection. This is the first study to report on the reliability of radiological evaluation during neo-adjuvant endocrine therapy. In this study, mammography was the most reliable radiological method, with stronger correlation and small mean absolute error. Non- visible observations in neo-adjuvant endocrine therapy did not always reflect pCR. Hence, in the neo-adjuvant endocrine therapy setting, radiological complete responses should be interpreted carefully, especially in MRI, and use of other modalities or improved image processing methods may be considered. Citation Format: Blok EJ, Charehbili A, Kroep JR, Seynaeve CM, van de Velde CJH, Kuppen PJK. Radiological evaluation of neo-adjuvant endocrine therapy in hormone-receptor positive early breast cancer. [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 P6-01-05.

TCGASpliceSeq a compendium of alternative mRNA splicing in cancer.

TCGA's RNASeq data represent one of the largest collections of cancer transcriptomes ever assembled. RNASeq technology, combined with computational tools like our SpliceSeq package, provides a comprehensive, detailed view of alternative mRNA splicing. Aberrant splicing patterns in cancers have been implicated in such processes as carcinogenesis, de-differentiation and metastasis. TCGA SpliceSeq (http://bioinformatics.mdanderson.org/TCGASpliceSeq) is a web-based resource that provides a quick, user-friendly, highly visual interface for exploring the alternative splicing patterns of TCGA tumors. Percent Spliced In (PSI) values for splice events on samples from 33 different tumor types, including available adjacent normal samples, have been loaded into TCGA SpliceSeq. Investigators can interrogate genes of interest, search for the genes that show the strongest variation between or among selected tumor types, or explore splicing pattern changes between tumor and adjacent normal samples. The interface presents intuitive graphical representations of splicing patterns, read counts and various statistical summaries, including percent spliced in. Splicing data can also be downloaded for inclusion in integrative analyses. TCGA SpliceSeq is freely available for academic, government or commercial use.

Abstract 3400A: Development and application of an immunohistochemistry-based clinical assay for evaluating Folate Receptor Alpha (FRα) expression in a phase I clinical trial of IMGN853

Abstract A biomarker-based patient selection strategy, coupled with the co-development of a companion diagnostic, is key to the successful development of molecularly targeted cancer therapeutics. IMGN853 is a Folate Receptor Alpha (FRα)-targeting antibody-drug conjugate (ADC) consisting of an anti-FRα antibody linked to DM4, a highly cytotoxic maytansinoid, via a cleavable disulfide linker. FRα is a glycosyl-phosphatidylinositol-linked membrane protein commonly over-expressed in several solid tumor types including epithelial ovarian cancer (EOC), endometrial cancer and lung adenocarcinoma, with limited expression in normal tissues. Previously reported preclinical data demonstrated regression or significant inhibition of tumor growth by the conjugate in tumor models with clinically relevant levels of FRα expression. IMGN853 is currently in a phase I clinical trial for safety and tolerability in patients with FRα-positive solid tumors. Preliminary evidence of clinical activity has been observed in patients receiving IMGN853 treatment. Immunohistochemistry (IHC) is one of the most widely adopted techniques in clinical labs for semi-quantitative determination of protein expression in different cellular compartments. We have developed an IHC assay to support the FRα-expression based patient selection strategy in the clinical development of IMGN853. To this end, a novel murine monoclonal antibody with high specificity for human FRα was generated. This antibody, 353-2.1, is compatible with formalin fixed and paraffin embedded (FFPE) tissue samples and can recognize the same pool of FRα molecules as IMGN853, making it an ideal candidate for a companion diagnostic for IMGN853. The antibody was used to develop and optimize an assay that covers a broad dynamic range of FRα expression, allowing discrimination among high, moderate and low levels of expression. Data from tissue microarrays that cover a broad range of normal and tumor tissue types, as well as additional prevalence data in selected tumor types, were used to validate this assay. They also demonstrate that the FRα-expression data generated using this assay are consistent with previous findings. This clinical FRα IHC assay has been successfully used to measure FRα expression in more than 100 patient tumor samples submitted for testing in the ongoing IMGN853 phase I trial. A summary of FRα staining pattern and expression level data from these patients will be presented, as well as the prevalence in each tumor type. Citation Format: Jianhua Zhao, Alyssa LaBelle, Olga Ab, Krista Acosta, Al Yates, Yinghui Zhou, Angela Romanelli. Development and application of an immunohistochemistry-based clinical assay for evaluating Folate Receptor Alpha (FRα) expression in a phase I clinical trial of IMGN853. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3400A. doi:10.1158/1538-7445.AM2015-3400A

Alka-372-001: First-in-human, phase I study of entrectinib – an oral pan-trk, ROS1, and ALK inhibitor – in patients with advanced solid tumors with relevant molecular alterations.

2517 Background: Entrectinib (formerly RXDX-101) is a potent and selective oral small molecule inhibitor of the TrkA/B/C, ROS1, and ALK kinases. Schedule A (fasted, 4d on/3d off for 3wks, 1 wk rest) demonstrated significant antitumor activity (ASCO 2014). This abstract reports completion of Sch A and two other ongoing dosing schedules (B and C). Methods: Pts with advanced solid tumors with molecular alterations in TrkA, ROS1 or ALK were treated in Sch B (QD) or Sch C (4d on/3d off), both in fed state. Results: 31 pts were treated in Sch A (N=19), B (N=6), or C (N=6). In Sch A, doses > 800 mg/m2 did not increase exposure significantly. Thus, accrual in Sch A was closed. Various dose levels (mg/m2) were explored in Sch B [200 (n=3); 400 (n=3)] and Sch C [400 (n=3); 800 (n=3)]. 7 pts had objective responses: 6 PR, 1CR (see Table). We are the first to report clinical activity of a Trk inhibitor in a pt with NTRK1+ (encoding TrkA) CRC. Of 7 ROS1-rearranged evaluable/measurable NSCLC pts, 4 have had an objective response (ORR: 57%), with a median duration of 6+ months. Moreover, in ROS1 pts treated at ≥ 400 mg/m2, the ORR was 80% (4 of 5 pts). Entrectinib is well tolerated. The majority of pts reported G1/ G2 AEs. 13 pts reported ≥ G3 AEs. Asthenia and muscle weakness were possibly related ≥ grade 3 AEs (both reversible). No DLTs have been reported to date. In Sch A, entrectinib was readily absorbed and exposures increased dose-proportionally up to 800 mg/m2. In fed state, entrectinib exposures were approx. 2x compared to fasted state. Conclusions: In this trial with entrectinib administered in 3 different dosing schedules, significant antitumor response was observed in pts with relevant molecular alterations, notably ROS1-rearranged NSCLC at doses ≥ 400 mg/m2/day and the only NTRK1 rearranged pt treated to date. Accrual in Sch B and C continues until RP2D is achieved, followed by dedicated studies in selected tumor types. Clinical trial information: NCT02097810.Objective responses. Tumor type (alteration) Sch/Dose (mg/m2) Best Response Duration of Response (cycles) NSCLC (ALK) A/800 PR 10 NSCLC (ROS1) A/1200 PR 14+ C/400 PR 7+ C/400 CR 5+ B/400 PR 3+ CRC (NTRK1) A/1600 PR 3 Neuroblastoma (ALK) A/800 PR 9

Beyond DNA repair: DNA-PK function in cancer.

The DNA-dependent protein kinase (DNA-PK) is a pivotal component of the DNA repair machinery that governs the response to DNA damage, serving to maintain genome integrity. However, the DNA-PK kinase component was initially isolated with transcriptional complexes, and recent findings have illuminated the impact of DNA-PK-mediated transcriptional regulation on tumor progression and therapeutic response. DNA-PK expression has also been correlated with poor outcome in selected tumor types, further underscoring the importance of understanding its role in disease. Herein, the molecular and cellular consequences of DNA-PK are considered, with an eye toward discerning the rationale for therapeutic targeting of DNA-PK. Although DNA-PK is classically considered a component of damage response, recent findings illuminate damage-independent functions of DNA-PK that affect multiple tumor-associated pathways and provide a rationale for the development of novel therapeutic strategies.