Characterization and impact of non-canonical WNT signaling on outcomes of urothelial carcinoma

BACKGROUND

Non-canonical WNT family (WNT5A pathway) signaling via WNT5A through ROR1 and its partner, ROR2, or Frizzled2 (FZD2) is linked to processes driving tumorigenesis and therapy resistance. We utilized a large dataset of urothelial carcinoma (UC) tumors to characterize non-canonical WNT signaling through WNT5A, ROR1, ROR2, or FZD2 expression.

METHODS

NextGen Sequencing of DNA (592 genes or WES)/RNA (WTS) was performed for 4125 UC tumors submitted to Caris Life Sciences. High and low expression of WNT5A, ROR1, ROR2, and FZD2 was defined as ≥ top and

RESULTS

WNT5A pathway gene expression varied significantly between primary versus metastatic sites: WNT5A (25.2 vs. 16.8 TPM), FZD2 (3.2 vs. 4.05), ROR1 (1.7 vs. 2.1), and ROR2 (2.4 vs. 2.6) p < 0.05 for all. Comparison of high- and low-expression subgroups revealed variation in the prevalence of TP53, FGFR3, and RB1 pathogenic mutations, as well as increasing T cell-inflamed scores as expression of the target gene increased. High gene expression for ROR2 (HR 1.31, 95% CI 1.15-1.50, p < 0.001) and FZD2 (HR 1.16, 95% CI 1.02-1.32, p = 0.024) was associated with worse OS.

CONCLUSION

Distinct genomic and immune landscapes for the four investigated WNT5A pathway components were observed in patients with UC. External validation studies are needed.

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Key Words

• FZD2
• Non‐canonical
• ROR
• Urothelial carcinoma
• WNT signaling
• WNT5A

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MESH Headings

• Humans
• Wnt Proteins/genetics
• Wnt Proteins/metabolism
• Carcinoma, Transitional Cell
• Urinary Bladder Neoplasms
• Wnt Signaling Pathway/genetics
• Receptor Tyrosine Kinase-like Orphan Receptors/genetics
• Wnt-5a Protein/genetics
• Wnt-5a Protein/metabolism

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Affiliation(s)

Margaret Meagher Department of UrologyUC San Diego School of MedicineLa JollaCaliforniaUSA
Harris Krause Caris Life SciencesPhoenixArizonaUSA
Andrew Elliott Caris Life SciencesPhoenixArizonaUSA
Alex Farrell Caris Life SciencesPhoenixArizonaUSA
Emmanuel S. Antonarakis Division of Hematology, Oncology, and TransplantationUniversity of MinnesotaMinnesotaUSA
Bruno Bastos Miami Cancer InstituteMiamiFloridaUSA Karmanos Cancer Institute, Department of OncologyWayne State University School of MedicineDetroitMichiganUSA
Elisabeth I. Heath Department of MedicineUC San Diego School of MedicineLa JollaCaliforniaUSA
Christina Jamieson Department of UrologyUC San Diego School of MedicineLa JollaCaliforniaUSA
Tyler F. Stewart Department of UrologyUC San Diego School of MedicineLa JollaCaliforniaUSA
Aditya Bagrodia Department of UrologyUC San Diego School of MedicineLa JollaCaliforniaUSA
Chadi Nabhan Caris Life SciencesPhoenixArizonaUSA
Matt Oberley Caris Life SciencesPhoenixArizonaUSA
Rana R. McKay Department of UrologyUC San Diego School of MedicineLa JollaCaliforniaUSA Barbara Ann Karmanos Cancer InstituteDetroitUSA
Amirali Salmasi Department of UrologyUC San Diego School of MedicineLa JollaCaliforniaUSA

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A Phase 2, Double-blind, Randomized Controlled Trial of PROSTVAC in Prostate Cancer Patients on Active Surveillance

BACKGROUND

There is an unmet clinical need for interventions to prevent disease progression in patients with localized prostate cancer on active surveillance (AS).

OBJECTIVE

To determine the immunologic response to the PROSTVAC vaccine and the clinical indicators of disease progression in patients with localized prostate cancer on AS.

DESIGN, SETTING, AND PARTICIPANTS

This was a phase 2, double-blind, randomized controlled trial in 154 men with low- or intermediate-risk prostate cancer on AS.

INTERVENTION

Participants were randomized (2:1) to receive seven doses of subcutaneous PROSTVAC, a vaccinia/fowlpox viral vector-based immunotherapy containing a prostate-specific antigen (PSA) transgene and three T-cell co-stimulatory molecules, or an empty fowlpox vector (EV) over 140 d.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was the change from baseline in CD4 and CD8 T-cell infiltration in biopsy tumor tissue. Key secondary outcomes were safety and changes in prostate biopsy tumor pathology, peripheral antigen-specific T cells, and serum PSA. Continuous variables were compared using nonparametric tests. Categorical variables were compared using Fisher's exact test.

RESULTS AND LIMITATIONS

The PROSTVAC/EV vaccination was well tolerated. All except one participant completed the vaccination series. Changes in CD4 or CD8 density in biopsy tumor tissue did not differ between the PROSTVAC and EV arms. The proportions of patients with Gleason upgrading to grade group 3 after treatment was similar between the arms. There were no differences in postvaccination peripheral T-cell responses or the PSA change from baseline to 6-mo post-treatment follow-up between the groups.

CONCLUSIONS

In this first-of-kind trial of immunotherapy in patients on AS for prostate cancer, PROSTVAC did not elicit more favorable prostate tissue or peripheral T-cell responses than the EV. There was no difference between the arms in clinicopathologic effects. Despite the null findings, this is the first study reporting the feasibility and acceptability of an immunotherapy intervention in the AS setting.

PATIENT SUMMARY

We looked at responses after an experimental prostate cancer vaccine in patients with prostate cancer on active surveillance (AS). Participants who received the vaccine did not show more favorable outcomes than those receiving the control. Despite these findings, this is the first report showing the feasibility and acceptability of immunotherapy for prostate cancer in patients on AS.

A Phase I Study of Combination Olaparib and Radium-223 in Men with Metastatic Castration-Resistant Prostate Cancer (mCRPC) with Bone Metastases (COMRADE)

Given that radium-223 is a radiopharmaceutical that induces DNA damage, and olaparib is a PARP inhibitor that interferes with DNA repair mechanisms, we hypothesized their synergy in metastatic castration-resistant prostate cancer (mCRPC). We sought to demonstrate the safety and efficacy of olaparib + radium-223. We conducted a multicenter phase I 3+3 dose escalation study of olaparib with fixed dose radium-223 in patients with mCRPC with bone metastases. The primary objective was to establish the RP2D of olaparib, with secondary objectives of safety, PSA response, alkaline phosphatase response, radiographic progression-free survival (rPFS), overall survival, and efficacy by homologous recombination repair (HRR) gene status. Twelve patients were enrolled; all patients received a prior androgen receptor signaling inhibitor (ARSI; 100%) and 3 patients (25%) prior docetaxel. Dose-limiting toxicities (DLT) included cytopenias, fatigue, and nausea. No DLTs were seen in the observation period however delayed toxicities guided the RP2D. The RP2D of olaparib was 200 mg orally twice daily with radium-223. The most common treatment-related adverse events were fatigue (92%) and anemia (58%). The rPFS at 6 months was 58% (95% confidence interval, 27%-80%). Nine patients were evaluable for HRR gene status; 1 had a BRCA2 alteration (rPFS 11.8 months) and 1 had a CDK12 alteration (rPFS 3.1 months). Olaparib can be safely combined with radium-223 at the RP2D 200 mg orally twice daily with fixed dose radium-223. Early clinical benefit was observed and will be investigated in a phase II study.

Characterization and impact of Wnt5A signaling on outcomes of urothelial carcinoma

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Background: Active Wnt signaling via WNT5A through ROR1 and its partner, ROR2, or WNT5A/frizzled 2 (FZD2) is linked to processes driving tumorigenesis, disease progression and therapy resistance. The role of this pathway in the pathogenesis of urothelial carcinoma (UC) is not fully elucidated. In adult tissue, ROR1 is largely absent, which makes it ideal for targeted therapies, with several ROR1 targeting agents in early clinical development. We utilized a large dataset of molecularly characterized UC tumors to investigate the significance of Wnt5a/ ROR1, ROR2 or FZD2 transcriptional expression. Methods: NextGen Sequencing of DNA (592 genes or WES)/RNA (WTS) was performed for 4743 UC tumors submitted to Caris Life Sciences (Phoenix, AZ). PD-L1 expression (SP142; Positive (+): ³2+, ³%5) was tested by IHC. Gene expression profiles were analyzed for a transcriptional signature predictive of response to immunotherapy (T cell-inflamed; Bao, 2020). WNT5a, ROR1, ROR2, and FZD2-high and -low expression were defined as ³ top and < bottom quartile of transcripts per million (TPM), respectively. Mann-Whitney U and X2/Fisher-Exact tests were applied where appropriate, with P-values adjusted for multiple comparisons ( q < .05). Real-world overall survival (OS) information was obtained from insurance claims data and Kaplan Meier estimates were calculated for molecularly defined cohorts. Results: We observed similar expression of these WNT5A signaling pathway genes between upper (N=795) and lower tract UC (N=3,204): WNT5A (22.7 v. 22.2 median TMP (mTPM), q = .18), FZD2 (3.4 v 3.5, q = .93), ROR1 (2.0 v. 1.7, q = .05), and ROR2 (2.1 v 2.5, q < .01). WNT family gene expression varied significantly between primary (N=2,756) and metastatic sites (N=1,361): WTN5A (25.2 v 16.8 mTPM), FZD2 (3.2 v 4.05), ROR1 (1.7 v 2.1), and ROR2 (2.4 v 2.6) for primary vs. metastatic sites respectively ( q < .05 for all). Comparison of high- and low-expression subgroups revealed variation in the prevalence of TP53, FGFR3 and RB1 mutations, as well as PDL1+ staining and T cell-inflamed scores (Table). High gene expression for ROR2 (HR 0.66, 95% CI 0.56-0.78, p < .001) and FZD2 (HR 0.75, 95% CI 0.63-0.89, p < .001) was associated with worse OS compared to low gene expression. No significant difference in OS was observed for WNT5A (HR 0.97, 95% CI 0.82-1.15, p < .76) and ROR1 (HR 0.86, 95% CI 0.72-1.01, p < .068). Conclusions: Distinct genomic and immune landscapes for the four investigated WNT pathway components were observed and should be leveraged to identify combination therapies that complement the current pipeline of WNT pathway-targeting drugs. [Table: see text]

Immunotherapy to prevent progression on active surveillance study (IPASS): A phase II, randomized, double-blind, controlled trial of PROSTVAC in prostate cancer patients who are candidates for active surveillance

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Background: Immunotherapy could potentially prevent disease progression for early-stage prostate cancer. In this randomized Phase 2 clinical trial, we evaluated the clinical effects of PROSTVAC, a vaccinia/fowlpox viral vector-based immunotherapy that contains PSA and three T-cell costimulatory molecules, in patients with localized prostate cancer. Methods:154 patients with clinically localized, low- or favorable intermediate-risk prostate cancer active surveillance were randomized (2:1) to receive 7 doses of subcutaneous PROSTVAC or placebo (empty fowlpox vector) over 140 days. Post-intervention prostate biopsy was performed 7-14 days after the last dose. Participants were followed for 6 months post-treatment. The primary outcome was change from baseline to post-vaccination in CD4 and CD8 T cell infiltration in biopsy tumor tissue. Secondary outcomes included changes in prostate biopsy Gleason grade (Grade Group) and serum PSA. Results: There were no differences in CD4 and CD8 densities (count of cells/mm2) in post-treatment biopsy tumor tissue between groups ( p = 0.63 and p = 0.75, respectively). Compared to placebo, patients who received PROSTVAC were less likely to demonstrate upgrading at follow-up biopsy, but this difference did not attain significance (22% vs. 40%, p= 0.08). There was no difference in the change of PSA from baseline to 6 months post-treatment between arms ( p= 0.30). Conclusions: In this first-of-kind trial of immunotherapy for localized prostate cancer, PROSTVAC was well tolerated but did not elicit significant prostate tissue T-cell responses compared to placebo. The favorable post-treatment biopsy grade findings in PROSTVAC patients merit further evaluation and longer-term clinical follow-up. Clinical trial information: NCT02326805.

Clonal Expansion of Stem/Progenitor Cells in Cancer, Fibrotic Diseases, and Atherosclerosis, and CD47 Protection of Pathogenic Cells

We proposed and demonstrated that myelogenous leukemia has a preleukemic phase. In the premalignant phase, normal hematopoietic stem cells (HSCs) gradually accumulate mutations leading to HSC clonal expansion, resulting in the emergence of leukemic stem cells (LSCs). Here, we show that preleukemic HSCs are the basis of clonal hematopoiesis, as well as late-onset blood diseases (chronic-phase chronic myeloid leukemia, myeloproliferative neoplasms, and myelodysplastic disease). The clones at some point each trigger surface expression of "eat me" signals for macrophages, and in the clones and their LSC progeny, this is countered by upregulation of "don't eat me" signals for macrophages such as CD47,opening the possibility of CD47-based therapies. We include evidence that similar processes result in fibroblast expansion in a variety of fibrotic diseases, and arterial smooth muscle clonal expansion is a basis of atherosclerosis, including upregulation of both "eat me" and "don't eat me" molecules on the pathogenic cells.

Activation of NF-κB and p300/CBP potentiates cancer chemoimmunotherapy through induction of MHC-I antigen presentation

Many cancers evade immune rejection by suppressing major histocompatibility class I (MHC-I) antigen processing and presentation (AgPP). Such cancers do not respond to immune checkpoint inhibitor therapies (ICIT) such as PD-1/PD-L1 [PD-(L)1] blockade. Certain chemotherapeutic drugs augment tumor control by PD-(L)1 inhibitors through potentiation of T-cell priming but whether and how chemotherapy enhances MHC-I-dependent cancer cell recognition by cytotoxic T cells (CTLs) is not entirely clear. We now show that the lysine acetyl transferases p300/CREB binding protein (CBP) control MHC-I AgPPM expression and neoantigen amounts in human cancers. Moreover, we found that two distinct DNA damaging drugs, the platinoid oxaliplatin and the topoisomerase inhibitor mitoxantrone, strongly up-regulate MHC-I AgPP in a manner dependent on activation of nuclear factor kappa B (NF-κB), p300/CBP, and other transcription factors, but independently of autocrine IFNγ signaling. Accordingly, NF-κB and p300 ablations prevent chemotherapy-induced MHC-I AgPP and abrogate rejection of low MHC-I-expressing tumors by reinvigorated CD8+ CTLs. Drugs like oxaliplatin and mitoxantrone may be used to overcome resistance to PD-(L)1 inhibitors in tumors that had "epigenetically down-regulated," but had not permanently lost MHC-I AgPP activity.

Characterization of Wnt signaling pathway (WSP) aberrations in advanced prostate cancer

203

Background: Aberrations in Wnt signaling pathway (WSP) are implicated in disease progression and resistance of multiple malignancies including prostate cancer (PCa). We sought to characterize the clinical phenotype and molecular genotype of PCa patients with WSP alterations. Methods: Eligible patients included those with PCa having undergone clinical-grade next generation DNA sequencing of tumor derived from prostate or metastasis tissue. We identified patients with somatic activating mutations in CTNNB1 and RSPO2, or inactivating mutations in APC, RNF43, or ZNRF3. Patient and disease characteristics were collected. Clinical and outcome parameters were associated with WSP mutation status using STATA(V. 13.1, College Station, Texas). Results: A total of 169 patients were identified of whom 29 (18.1%) had a WSP activating mutation. Median age of the overall cohort was 64.85 (IQR 56.77, 70.36). 115 (68.0%) patients had Gleason 8-10 disease, 34 (20.1%) presented with de novo metastatic disease, 85 (50.3%) developed CRPC and 23 (13.6%) developed visceral metastases. Clinical characteristics were similar between biomarker groups. There was no association with the presence of a Wnt activating mutation and RB1, p53, pTEN, or BRCA1/2 alteration. Median time to CRPC was 39.42 (IQR 14.50 – 87.52) and 24.39 (IQR 14.99 – 46.03) months for no-WSP and WSP-aberrant respectively. Median 5-year OS was 83.7% (95% CI 73.0-90.4%) and 79.6% (95% CI 52.9 – 92.2%) months for no-WSP and WSP-aberrant respectively. Table evaluates biomarker status with time to CRPC development and overall survival (OS). Conclusions: We observe that somatic WSP activating mutations are present in 18.1% of patients with mPCa, consist with prior reports. Understanding the clinical significance of WSP alterations is critical to inform treatment strategies in patients with advanced disease.[Table: see text]

Hypoxia-induced PIM kinase and laminin-activated integrin α6 mediate resistance to PI3K inhibitors in bone-metastatic CRPC

Bone-metastatic castration-resistant prostate cancer (CRPC) is lethal due to inherent resistance to androgen deprivation therapy, chemotherapy, and targeted therapies. Despite the fact that a majority of CRPC patients (approximately 70%) harbor a constitutively active PI3K survival pathway, targeting the PI3K/mTOR pathway has failed to increase overall survival in clinical trials. Here, we identified two separate and independent survival pathways induced by the bone tumor microenvironment that are hyperactivated in CRPC and confer resistance to PI3K inhibitors. The first pathway involves integrin α6β1-mediated adhesion to laminin and the second involves hypoxia-induced expression of PIM kinases. In vitro and in vivo models demonstrate that these pathways transduce parallel but independent signals that promote survival by reducing oxidative stress and preventing cell death. We further demonstrate that both pathways drive resistance to PI3K inhibitors in PTEN-negative tumors. These results provide preclinical evidence that combined inhibition of integrin α6β1 and PIM kinase in CRPC is required to overcome tumor microenvironment-mediated resistance to PI3K inhibitors in PTEN-negative tumors within the hypoxic and laminin-rich bone microenvironment.

Protein Kinase N1 control of androgen-responsive serum response factor action provides rationale for novel prostate cancer treatment strategy

Sustained reliance on androgen receptor (AR) after failure of AR-targeting androgen deprivation therapy (ADT) prevents effective treatment of castration-recurrent (CR) prostate cancer (CaP). Interfering with the molecular machinery by which AR drives CaP progression may be an alternative therapeutic strategy but its feasibility remains to be tested. Here, we explore targeting the mechanism by which AR, via RhoA, conveys androgen-responsiveness to serum response factor (SRF), which controls aggressive CaP behavior and is maintained in CR-CaP. Following a siRNA screen and candidate gene approach, RNA-Seq studies confirmed that the RhoA effector Protein Kinase N1 (PKN1) transduces androgen-responsiveness to SRF. Androgen treatment induced SRF-PKN1 interaction, and PKN1 knockdown or overexpression severely impaired or stimulated, respectively, androgen regulation of SRF target genes. PKN1 overexpression occurred during clinical CR-CaP progression, and hastened CaP growth and shortened CR-CaP survival in orthotopic CaP xenografts. PKN1's effects on SRF relied on its kinase domain. The multikinase inhibitor lestaurtinib inhibited PKN1 action and preferentially affected androgen regulation of SRF over direct AR target genes. In a CR-CaP patient-derived xenograft, expression of SRF target genes was maintained while AR target gene expression declined and proliferative gene expression increased. PKN1 inhibition decreased viability of CaP cells before and after ADT. In patient-derived CaP explants, lestaurtinib increased AR target gene expression but did not significantly alter SRF target gene or proliferative gene expression. These results provide proof-of-principle for selective forms of ADT that preferentially target different fractions of AR's transcriptional output to inhibit CaP growth.

A Randomized, Double-blind, Phase II Trial of PSA-TRICOM (PROSTVAC) in Patients with Localized Prostate Cancer: The Immunotherapy to Prevent Progression on Active Surveillance Study

The Immunotherapy to Prevent Progression on Active Surveillance Study is the first trial of immunotherapy for localized prostate cancer. We randomized active surveillance patients to PSA-TRICOM (PROSTVAC) or placebo for 5mo. Final results will be available in 2019.

Abstract B23: Novel epidermal growth factor receptor inhibitors cross the blood-brain barrier and inhibit the growth of metastatic non-small cell lung cancer

Deaths from solid tumors are often not due to the primary lesion but to metastatic disease at distal sites such as the lung, liver, and brain. Patients with non-small cell lung cancer (NSCLC) experience brain metastases, a poor prognostic marker, at an incidence rate of 30-50%. A significant proportion of the metastatic tumors express activating mutations of the EGFR, including exon 19 deletions as well as point mutations within the enzyme active site (L858R), which confer increased sensitivity to EGFR inhibitors. However, current small-molecule therapeutics poorly inhibit the growth of NSCLC brain metastases due to difficulty crossing the blood-brain barrier and harmful off-target effects. Thus, NSCLC patients with brain metastases have access to very few emerging treatment options.

We have synthesized a novel class of compounds that irreversibly inhibit the epidermal growth factor receptor (EGFR) in the nanomolar range in vitro, and demonstrate a high degree of selectivity for EGFR mutants found frequently in NSCLC, in particular exon 19 deletions and L858R mutations, while sparing wild-type (WT) EGFR. Two compounds, LL-001 and LL-019, from Capella Therapeutics, Inc., inhibited L858R EGFR-mediated autophosphorylation and phosphorylation of downstream targets Akt and ERK MAP kinase at a concentration of approximately 100nM and blocked the kinase activity of an EGFR mutant, T790M, which confers resistance to first-generation EGFR inhibitors. In contrast, these compounds only weakly inhibited WT EGFR and failed to inhibit either the insulin receptor or insulin-like receptor-I, suggesting that these inhibitors would produce minimal off-target side effects in treated patients. Both compounds induced full remission of subcutaneous tumors with the human NSCLC cell line H1975 (T790M/L858R+). Most notably, pharmacokinetic studies showed that these compounds, when administered at a concentration of 150mg/kg in mice, showed no signs of toxicity and were found in the brain at concentrations ranging from 12-171 times higher than the GI50 for inhibition of EGFR+ NSCLC cell line proliferation in vitro.

To determine whether these compounds could treat NSCLC brain metastases, we developed intracranial and intracardiac injection orthotopic xenograft models of brain metastatic NSCLC. LL-001 and LL-019 could induce remission of brain tumors in mice injected intracranially with the human NSCLC cell line HCC827-luciferase, which expresses an exon 19 deletion mutant of EGFR. Likewise, both compounds inhibited the growth of the human NSCLC cell line PC9M in an intracardiac model of brain metastatic NSCLC, and greatly extended the survival of mice compared to those receiving vehicle alone. Our results indicate that LL-001 and LL-019 can cross the blood-brain barrier at levels sufficient to inhibit the growth of brain metastatic lung cancer, with minimal deleterious off-target effects. These compounds show promise for the treatment of critically underserved NSCLC patients with brain metastases.

Citation Format: Michelle Muldong, Christina Jamieson, Yun Oliver Long, Ida Deichaite, David W. Anderson, Alan Lewis, Nicholas A. Cacalano. Novel epidermal growth factor receptor inhibitors cross the blood-brain barrier and inhibit the growth of metastatic non-small cell lung cancer [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr B23.

Crohn's disease: First diagnosis in pregnancy and management

This case addresses the difficulty in the initial diagnosis of severe Crohn's disease in pregnancy as well as the challenges of instituting remission therapy towards the end of second trimester. The patient's course was complicated by recurrent hospital admissions and intolerance to diet requiring temporary nasogastric feeding. Medical management included the use of biological agents during pregnancy, which allowed for better symptomatic control. She sustained no further complications and underwent a successful vaginal delivery of a healthy baby at 37 weeks' gestation.

A phase I, open-label, dose-escalation, multicenter study of the JAK2 inhibitor NS-018 in patients with myelofibrosis

NS-018 is a Janus-activated kinase 2 (JAK2)-selective inhibitor, targeting the JAK–signal transducer and activator of transcription (STAT) pathway that is deregulated in myelofibrosis. In this phase I, dose-escalation portion of a phase I/II study, patients with myelofibrosis received oral NS-018 in continuous 28-day cycles. The primary study objective was to evaluate safety, tolerability and clinically active dose of NS-018. Forty-eight patients were treated; 23 (48%) had previously received a JAK inhibitor (JAKi). The most common drug-related adverse events were thrombocytopenia (27%)/anemia (15%) for hematologic events, and dizziness (23%)/nausea (19%) for non-hematologic events. Once daily NS-018 at 300 mg was chosen as the phase II study dose based on improved tolerability compared with higher doses. A ⩾50% reduction in palpable spleen size was achieved in 56% of patients (47% of patients with prior JAKi treatment), and improvements were observed in myelofibrosis-associated symptoms. Bone marrow fibrosis grade (local assessment) improved from baseline in 11/30 evaluable patients (37%) after 3 cycles of NS-018. JAK2 allele burden was largely unchanged. Changes in cytokine/protein levels were noted after 4 weeks of treatment. NS-018 reached peak plasma concentration in 1–2 h and did not accumulate with multiple dosing. NS-018 will be assessed in patients with previous JAKi exposure in the phase II portion.

A phase 2 randomized dose-ranging study of the JAK2-selective inhibitor fedratinib (SAR302503) in patients with myelofibrosis

In this phase 2 open-label randomized study, 31 patients with intermediate-2 or high-risk myelofibrosis received fedratinib 300, 400 or 500 mg once daily in consecutive 4-week cycles. Mean spleen volume reductions at 12 weeks (primary end point) were 30.3% (300 mg), 33.1% (400 mg) and 43.3% (500 mg). Spleen response rates (patients achieving ⩾35% spleen reduction) at 12/24 weeks were 30%/30% (300 mg), 50%/60% (400 mg) and 64%/55% (500 mg), respectively. By 4 weeks, improvements in myelofibrosis (MF)-associated symptoms were observed. At 48 weeks, 68% of patients remained on fedratinib and 16% had discontinued because of adverse events (AEs). Common grade 3/4 AEs were anemia (58%), fatigue (13%), diarrhea (13%), vomiting (10%) and nausea (6%). Serious AEs included one case of reversible hepatic failure and one case of Wernicke's encephalopathy (after analysis cutoff). Fedratinib treatment led to reduced STAT3 phosphorylation but no meaningful change in JAK2V617F allele burden. Significant modulation (P<0.05, adjusted for multiple comparisons) of 28 cytokines was observed, many of which correlated with spleen reduction. These data confirm the clinical activity of fedratinib in MF. After the analysis cutoff date, additional reports of Wernicke's encephalopathy in other fedratinib trials led to discontinuation of the sponsored clinical development program.

Immunosuppressive plasma cells impede T-cell-dependent immunogenic chemotherapy

Cancer-associated genetic alterations induce expression of tumour antigens that can activate CD8(+) cytotoxic T cells (CTLs), but the microenvironment of established tumours promotes immune tolerance through poorly understood mechanisms. Recently developed therapeutics that overcome tolerogenic mechanisms activate tumour-directed CTLs and are effective in some human cancers. Immune mechanisms also affect treatment outcome, and certain chemotherapeutic drugs stimulate cancer-specific immune responses by inducing immunogenic cell death and other effector mechanisms. Our previous studies revealed that B cells recruited by the chemokine CXCL13 into prostate cancer tumours promote the progression of castrate-resistant prostate cancer by producing lymphotoxin, which activates an IκB kinase α (IKKα)-BMI1 module in prostate cancer stem cells. Because castrate-resistant prostate cancer is refractory to most therapies, we examined B cell involvement in the acquisition of chemotherapy resistance. Here we focus on oxaliplatin, an immunogenic chemotherapeutic agent that is effective in aggressive prostate cancer. We show that mouse B cells modulate the response to low-dose oxaliplatin, which promotes tumour-directed CTL activation by inducing immunogenic cell death. Three different mouse prostate cancer models were refractory to oxaliplatin unless genetically or pharmacologically depleted of B cells. The crucial immunosuppressive B cells are plasmocytes that express IgA, interleukin (IL)-10 and programmed death ligand 1 (PD-L1), the appearance of which depends on TGFβ receptor signalling. Elimination of these cells, which also infiltrate human-therapy-resistant prostate cancer, allows CTL-dependent eradication of oxaliplatin-treated tumours.

Abstract A10: Suppressor of cytokine signaling (SOCS)-3 and the C-X-C chemokines CXCL1 and CXCL2 promote tumor aggressiveness and radiation resistance in pancreatic cancer

Despite recent advances in our understanding of pancreatic ductal adenocarcinoma (PDA), it remains a poorly understood, devastating disease that is largely resistant to all standard treatment modalities. Much effort has been made to identify novel tumor suppressor genes, biomarkers of metastatic behavior, and targets for molecular therapeutics that can improve prognosis and quality of life for PDA patients. Despite the finding that the pro-inflammatory C-X-C family chemokines CXCL1 and CXCL2 are expressed in a significant fraction of human PDA tissues and are known to promote metastasis in bladder and breast cancer, very little is known of its regulation and its role in the progression of PDA. Our laboratory has identified a mechanism by which CXCL1 and CXCL2 expression is regulated in human PDA. CXCL1/2 expression is repressed by the Signal Transducer and Activator of Transcription (STAT)-3 and conversely, the Suppressor of Cytokine Signaling (SOCS)-3, a STAT3 inhibitor, promotes CXCL1/2 gene activation and pro-inflammatory signaling in murine embryonic fibroblasts (MEFs) and human PDA cell lines. Ectopic expression of SOCS3 in the ASPC1 PDA cell line induces CXCL1 and CXCL2 expression and drives resistance to radiation and gemcitibine treatment. Treatment with neutralizing antibodies against CXCL1 or its receptor, CXCR2, sensitizes these cells to ionizing radiation. Further, using an orthotopic xenograft model of human PDA in immunodeficient mice, we demonstrated the in vivo relevance of this pathway. We found that mice injected with human SOCS3-positive human PDA cells have a shorter survival time and develop more aggressive disease compared to mice injected with control cells. We also have shown increased numbers of CD11b-positive granulocytes in the tumor microenvironment of SOCS3+ PDA tumors. We hypothesize that SOCS3 and CXCL1and CXCL2 promote human PDA pathogenesis by two mechanisms: (i) autocrine activation of the CXCR2 receptor expressed on human pancreatic cancer cells and (ii) pro-inflammatory recruitment of neutrophils to the tumor microenvironment.

Citation Format: Sisi Jiang, Giovanni Coppola, Evangeline Mose, Andrew Lowy, Christina Jamieson, Nicholas Cacalano. Suppressor of cytokine signaling (SOCS)-3 and the C-X-C chemokines CXCL1 and CXCL2 promote tumor aggressiveness and radiation resistance in pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr A10.

Abstract A43: Novel prostate cancer patient-derived xenograft models of bone metastatic castrate-resistant prostate cancer

Prostate cancer metastasis to bone occurs in 50-90% of men with advanced disease for which there is no cure. Bone metastasis leads to debilitating fractures and severe bone pain. It is associated with disease progression, therapy resistance, poor prognosis, and rapid decline. Androgen ablation therapy is standard of care for advanced prostate cancer, however, the role of androgens in bone metastatic prostate cancer is not understood. The effects of anti-androgens as seen on bone scans can also be inconsistent with the biochemical PSA response. There are few pre-clinical models to understand the interaction between the bone microenvironment and prostate cancer. It is essential to understand the unique interaction of prostate cancer with the bone environment and to develop novel therapies that target these pathways. Here we report the development of novel patient-derived intra-femoral xenograft models of prostate bone metastatic cancer.

METHODS: Surgical prostate cancer bone metastasis specimens were transplanted by direct injection into the femurs of Rag2-/-γc-/- mice or sub-cutaneously into the right flank. Patient-derived xenograft (PDX) tumors that grew out were analyzed for prostate cancer biomarker expression using quantitative RT-PCR and immunohistochemistry. Bone lesion formation was measured using micro-computed tomography (μCT).

RESULTS: Prostate cancer surgical bone metastasis specimens have been collected from which we have established new serially transplantable, prostate cancer bone metastasis xenograft models – PCSD1, PCSD4 and PCSD5. PCSD1 (Prostate Cancer San Diego 1) was molecularly characterized as advanced, luminal epithelial-type prostate cancer. PCSD1 intra-femoral xenografts formed mixed osteoblastic/osteolytic lesions that closely mimicked those of the patient. Treatment with the anti-androgen, bicalutamide, did not inhibit intra-femoral PCSD1 xenograft growth although there was a decrease in PSA as seen in some patients treated with anti-androgen who had discordant PSA and bone scan tests.

CONCLUSION: PCSD1, PCSD4 and PCSD5 are new patient-derived prostate cancer bone metastasis-derived xenograft models. PCSD1 xenograft model closely recapitulates the mixed osteolytic/osteoblastic bone metastatic lesions seen in patients, and we are using it to develop novel therapies for inhibiting prostate cancer growth in the bone-niche.

Citation Format: Christina Jamieson, Christina Wu, Amy Strasner, Jason R. Woo, Michelle Muldong, Young B. Jeong, Michael A. Liss, Omer Raheem, Tomonori Yamaguchi, Heather Leu, Deborah Marshall, Sheldon Morris, Nicholas A. Cacalano, Koichi Masuda, Catriona H.M. Jamieson, Anna A. Kulidjian, Christopher J. Kane. Novel prostate cancer patient-derived xenograft models of bone metastatic castrate-resistant prostate cancer. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr A43.

Abstract 4208: Suppressor of Cytokine Signaling (SOCS)-3 and the C-X-C chemokines CXCL1 and CXCL2 promote tumor aggessiveness and radiation resistance in pancreatic cancer

Despite recent advances in our understanding of pancreatic ductal adenocarcinoma (PDA), it remains a poorly understood, devastating disease that is largely resistant to all standard treatment modalities. Much effort has been made to identify novel tumor suppressor genes, biomarkers of metastatic behavior, and targets for molecular therapeutics that can improve prognosis and quality of life for PDA patients. Despite the finding that the pro-inflammatory C-X-C family chemokines CXCL1 and CXCL2 are expressed in a significant fraction of human PDA tissues and are known to promote metastasis in bladder and breast cancer, very little is known of its regulation and its role in the progression of PDA. Our laboratory has identified a mechanism by which CXCL1 expression is regulated in human PDA. CXCL1/2 expression is repressed by the Signal Transducer and Activator of Transcription (STAT)-3 and conversely, the Suppressor of Cytokine Signaling (SOCS)-3, a STAT3 inhibitor, promotes CXCL1/2 gene activation and pro-inflammatory signaling in murine embryonic fibroblasts (MEFs) and human PDA cell lines. Ectopic expression of SOCS3 in the ASPC1 PDA cell line induces CXCL1 and CXCL2 expression and drives resistance to radiation and gemcitibine treatment. Further, using an orthotopic xenograft model of human PDA in immunodeficient mice, we demonstrated the in vivo relevance of this pathway. We found that mice injected with human SOCS3-positive human PDA cells have a survival time compared and develop more aggressive disease compared to mice injected with control cells. We hypothesize that CXCL1and CXCL2 promote human PDA pathogenesis by two mechanisms: (i) autocrine activation of the CXCR2 receptor expressed on human pancreatic cancer cells and (ii) pro-inflammatory recruitment of neutrophils to the tumor microenvironment.

Citation Format: Sisi Jiang, Evangeline Mose, Giovanni Coppola, Andrew Lowy, Christina Jamieson, Nicholas A. Cacalano. Suppressor of Cytokine Signaling (SOCS)-3 and the C-X-C chemokines CXCL1 and CXCL2 promote tumor aggessiveness and radiation resistance in pancreatic cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4208. doi:10.1158/1538-7445.AM2014-4208

Inhibition of the phosphatidylinositol 3-kinase-Akt pathway enhances gamma-2 herpesvirus lytic replication and facilitates reactivation from latency

Cellular signalling pathways are critical in regulating the balance between latency and lytic replication of herpesviruses. Here, we investigated the effect of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway on replication of two gamma-2 herpesviruses, murine gammaherpesvirus-68 (MHV-68) and human herpesvirus-8/Kaposi's sarcoma-associated herpesvirus (HHV-8/KSHV). We found that de novo infection of MHV-68 induced PI3K-dependent Akt activation and the lytic replication of MHV-68 was enhanced by inhibiting the PI3K-Akt pathway with both chemical inhibitors and RNA interference technology. Inhibiting the activity of Akt using Akt inhibitor VIII also facilitated the reactivation of KSHV from latency. Both lytic replication and latency depend on the activity of viral transactivator RTA and we further show that the activity of RTA is increased by reducing Akt1 expression. The data suggest that the PI3K-Akt pathway suppresses the activity of RTA and thereby contributes to the maintenance of viral latency and promotes tumorigenesis.

Chronic myeloproliferative diseases with and without the Ph chromosome: some unresolved issues

Ph-positive chronic myeloid leukemia (CML) and Ph-negative chronic myeloproliferative diseases (MPDs), characterized in many cases by the presence of the JAK2(V617F) mutation, have many features in common and yet also show fundamental differences. In this review, we pose five discrete and related questions relevant to both categories of hematological malignancy, namely: What are the mechanisms that underlie disease progression from a relatively benign or chronic phase? By what therapeutic methods might one target residual leukemia stem cells in CML? Is JAK2(V617F) the original molecular event in MPD? What epigenetic events must have a role in dictating disease phenotype in MPDs? And finally, Will the benefits conferred by current or future JAK2(V617F) inhibitors equal or even surpass the clinical success that has resulted from the use of tyrosine kinase inhibitors in CML? These and others questions must be addressed and in some cases should be answered in the foreseeable future.

TG101348, a potent, highly selective JAK2 inhibitor, inhibits colony formation in stem cells from polycythemia vera patients and prevents JAK2V617F-mediated splenomegaly and death in a mouse model

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Background: The molecular pathogenesis of the myeloproliferative disorders (MPDs) polycythemia vera, essential thrombocythemia, and myelofibrosis with myeloid metaplasia has been strongly linked to an activating mutation of JAK2 (Janus Associated Kinase 2). A G-T transversion event in exon 14 that translates into a substitution of phenylalanine for valine at amino acid residue 617 leads to constitutive activation of JAK2V617F in a majority of these MPD cases. Methods: In order to address this unmet clinical need we designed, synthesized and performed preclinical evaluations on a series of structurally novel compounds optimized for JAK2 inhibition. Results: TG101348, a compound which potently inhibits JAK2V617F enzymatically and in human cells, was selected as a clinical development candidate from this medicinal chemistry campaign. TG101348 displays remarkable kinase specificity as shown by 83X selectivity versus JAK3 and potent inhibition of <2% of the kinases evaluated in a commercial, phylogenetically diverse panel of 212 kinases. TG101348 potently inhibits erythroid colony formation in patient-derived cells from polycythemia patients at doses 2–3X lower than in normal control patients. Consistent with this observation TG101348 inhibits JAK2-driven STAT5 phosphorylation, cell proliferation and cell survival in JAK2V617F-expressing cell lines. In vivo, TG101348 exhibits promising pharmacokinetic profiles in species ranging from mouse to monkey including oral availabilities >20%, and half-lives consistent with once or twice daily dosing. TG101348 reduces the number of circulating mutant JAK2 cells, inhibited splenomegaly and improved survival without significantly impacting normal hematocrit in an aggressive JAK2-driven circulating cell model of disease in rodents. Conclusion: TG101348 has considerable potential for the treatment of JAK2- driven myeloproliferative disorders based on its promising preclinical potency, selectivity and pharmaceutical properties.

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Solid-phase development of a L-hydroxybenzotriazole linker for heterocycle synthesis using analytical constructs

The development of a 1-hydroxybenzotriazole linker for the synthesis of heterocyclic derivatives is described, utilizing analytical construct methodology to facilitate the analysis of resin samples. A UV-chromophore-containing analytical construct enabled the accurate determination of resin loading and the automated monitoring of key reactions using only small quantities of resin. The syntheses of an array of isoxazole derivatives are reported.

Development and application of a carbonyl-(13)C-enriched backbone amide linker for solid-phase reaction monitoring

The synthesis and application of a carbonyl-(13)C backbone amide linker are described. The labeled unit is conveniently mixed with commercial resins, providing a rapid means of monitoring chemistry performed with this linker on solid support using conventional (13)C NMR methods.

Capecitabine (Xeloda) improves medical resource use compared with 5-fluorouracil plus leucovorin in a phase III trial conducted in patients with advanced colorectal carcinoma

Standard therapy for advanced or metastatic colorectal cancer consists of 5-fluorouracil plus leucovorin (5-FU/LV) administered intravenously (i.v.). Capecitabine (Xeloda), an oral fluoropyrimidine carbamate which is preferentially activated by thymidine phosphorylase in tumour cells, mimics continuous 5-FU and is a recently developed alternative to i.v. 5-FU/LV. The choice of oral rather than intravenous treatment may affect medical resource use because the two regimens do not require the same intensity of medical intervention for drug administration, and have different toxicity profiles. Here we examine medical resource use in the first-line treatment of colorectal cancer patients with capecitabine compared with those receiving the Mayo Clinic regimen of 5-FU/LV. In a prospective, randomised phase III clinical trial, 602 patients with advanced or metastatic colorectal cancer recruited from 59 centres worldwide were randomised to treatment with either capecitabine or the Mayo regimen of 5-FU/LV. In addition to clinical efficacy and safety endpoints, data were collected on hospital visits required for drug administration, hospital admissions, and drugs and unscheduled consultations with physicians required for the treatment of adverse events. Capecitabine treatment in comparison to 5-FU/LV in advanced colorectal carcinoma resulted in superior response rates (26.6% versus 17.9%, P=0.013) and improved safety including less stomatitis and myelosuppression. Capecitabine patients required substantially fewer hospital visits for drug administration than 5-FU/LV patients. Medical resource use analysis showed that patients treated with capecitabine spent fewer days in hospital for the management of treatment related adverse events than did patients treated with 5-FU/LV. In addition, capecitabine reduced the requirement for expensive drugs, in particular antimicrobials fluconazole and 5-HT3-antagonists to manage adverse events. As anticipated with an oral home-based therapy patients receiving capecitabine needed more frequent unscheduled home, day care, office and telephone consultations with physicians. In the light of clinical results from the phase III trial demonstrating increased efficacy in terms of response rate, equivalent time to progression (TTP) and survival (OS), and a superior safety profile, the results from this medical resource assessment indicate that capecitabine treatment of colorectal cancer patients results in a substantial resource use saving relative to the Mayo Clinic regimen of 5-FU/LV. This benefit is derived principally from the avoidance of hospital visits for i.v. drug administration, less expensive drug therapy for the treatment of toxic side-effects, and fewer treatment-related hospitalisations required during the course of therapy for adverse drug reactions in comparison to patients treated with 5-FU/LV.

Ambulatory blood pressure in heart failure

Ambulatory blood-pressure monitoring (ABPM) is accepted in the evaluation and management of hypertension. The use of ABPM in heart failure has received considerably less attention. Many patients with advanced heart failure experience disabling fatigue, orthostatic dizziness and symptoms of coronary and cerebrovascular insufficiency that may relate to periods of hypotension. These may be exacerbated by vasodilator drug therapy and may be difficult to evaluate by casual clinic recordings. ABPM in heart failure may help in the following: (i) evaluating time-dependent pharmacodynamic drug effects, such as peak and end-of-dose phenomena, tolerance and rebound; (ii) titrating ACE inhibitors and other drugs to highest-tolerated doses; and (iii) correlating circadian blood-pressure profiles with symptoms, quality of life, severity of heart failure, progression of ventricular and renal dysfunction, risks of stroke and myocardial infarction, and life expectancy. Devices for ABPM have been beset by problems of inaccuracy and unreliability. Standards for their manufacture and sale (including bench tests of accuracy against sphygmomanometry and intra-arterial recordings, and field tests of reliability) have been devised independently by several agencies, including the British Hypertension Society (BHS) and US Association for the Advancement of Medical Instrumentation (AAMI). A joint BHS/AAMI set of guidelines is in preparation. These guidelines emphasize the suitability of ABPM devices for hypertensive patients and those under general anesthesia, and may not be applicable to ambulant individuals with heart failure and blood pressures at or below the lower end of the evaluated ranges. Prospective studies of the accuracy and reliability of ABPM devices, their clinical utility and research potential should be undertaken in patients with heart failure before their informal and uncontrolled use in this population becomes widespread.

Inhibition of the ubiquitin-proteasome system in Alzheimer's disease

Alzheimer's disease is the most common cause of dementia in the elderly. Although several genetic defects have been identified in patients with a family history of this disease, the majority of cases involve individuals with no known genetic predisposition. A mutant form of ubiquitin, termed Ub(+1), has been selectively observed in the brains of Alzheimer's patients, including those with nonfamilial Alzheimer's disease, but it has been unclear why Ub(+1) expression should be deleterious. Here we show that Ub(+1) is an efficient substrate for polyubiquitination in vitro and in transfected human cells. The resulting polyubiquitin chains are refractory to disassembly by deubiquitinating enzymes and potently inhibit the degradation of a polyubiquitinated substrate by purified 26S proteasomes. Thus, expression of Ub(+1) in aging brain could result in dominant inhibition of the Ub-proteasome system, leading to neuropathologic consequences.

A new model for recognizing and rewarding the educational accomplishments of surgery faculty

Faculty members' educational endeavors have generally not received adequate recognition. The Association for Surgical Education in 1993 established a task force to determine the magnitude of this problem and to create a model to address the challenges and opportunities identified. To obtain baseline information, the task force reviewed information from national sources and the literature on recognizing and rewarding faculty members for educational accomplishments. The group also developed and mailed to surgery departments at all U.S. and Canadian medical schools a questionnaire asking about the educational endeavors of the surgery faculty and their recognition for such activities. The response rate after two mailings was only 56%, but the responses reaffirmed the inadequacy of systems for rewarding and recognizing surgeon-teachers and surgeon-educators, and confirmed that the distinction between the roles of teacher and educator was rarely made. The task force created a four-tier hierarchical model based on the designations teacher, master teacher, educator, and master educator as a framework to offer appropriate recognition and rewards to the faculty, and endorsed a broad definition of educational scholarship. Criteria for various levels of achievement, ways to demonstrate and document educational contributions, appropriate support and recognition, and suggested faculty ranks were defined for these levels. The task force recommended that each surgery department have within its faculty ranks a cadre of trained teachers, a few master teachers, and at least one educator. Departments with a major commitment to education should consider supporting a master educator to serve as a resource not only for the department but also for the department's medical school and other medical schools. Although this model was created for surgery departments, it is generalizable to other disciplines.