Ipafricept Ovarian Xenograft - AACR pathway antagonist ipafricept (FZD8-Fc, OMP-54F28) inhibits tumor growth and reduces tumor initiating cell frequency in ovarian patient-derived

Ipafricept Ovarian Xenograft - AACR pathway antagonist ipafricept (FZD8-Fc, OMP-54F28) inhibits tumor growth and reduces tumor initiating cell frequency in ovarian patient-derived

  • View
    217

  • Download
    5

Embed Size (px)

Text of Ipafricept Ovarian Xenograft - AACR pathway antagonist ipafricept (FZD8-Fc, OMP-54F28) inhibits...

  • Wnt pathway antagonist ipafricept (FZD8-Fc, OMP-54F28) inhibits tumor growth and reduces tumor initiating cell frequency in ovarian patient-derived xenograft models

    Marcus Fischer, Wan-Ching Yen, Chun Zhang, Randall Henner, Fiore Cattaruzza, Tracy Tang, Pete Yeung, Tanuka Biswas, John Lewicki, Austin Gurney, Ann M. Kapoun and Timothy Hoey

    OncoMed Pharmaceuticals Inc., Redwood City, California, 94063

    SUMMARY1. A subset of ovarian patient-derived xenograft tumors are responsive to the WNT antagonist ipafricept and combination of ipafricept with Taxol2. Responsive tumors have reduced levels of WNT target genes post-therapy3. Ipafricept reduces expression of WNT signaling molecule LEF1 and reduces the ovarian cancer stem cell frequency4. Anti-tumor activity of ipafricept is enhanced by pre-dosing ipafricept prior to Taxol5. Targeting the WNT pathway in ovarian cancer may benefit a subset of patients

    Preclinical PDX Models Have Identified Ovarian Cancers Responsive and Non-Responsive to Ipafricept

    RESULTSABSTRACTOvarian cancer is the deadliest gynecologic malignancy and the fifth leading cause of death from cancer in women in the U.S. The Wnt/-catenin pathway, which signals through the Frizzled (FZD) receptor family and several co-receptors, has long been implicated in cancer. We have developed ipafricept (FZD8-Fc, OMP-54F28), a recombinant fusion protein consist-ing of the ligand-binding domain of FZD8 and a human IgG1 Fc fragment. This fusion protein blocks Wnt signaling induced by multiple Wnt family members by binding and sequestering WNT. Using minimally passaged ovarian patient-derived xenograft tumors (PDX), we demonstrate that ipafricept is efficacious in combination with chemotherapy in ovarian cancer. Utilizing an in vivo serial transplantation assay, we quantified a reduction of the tumor initiating cell frequency by ipafricept in combination with paclitaxel. Additionally, we have discovered that pre-treatment with ipafricept several days prior to paclitaxel therapy enhances the activity of both agents when compared to delivering the drugs simultaneously. The anti-tumor effect observed is directly associated with a modulation of Wnt pathway gene sets. In responsive tumors, we discovered that a large number of WNT target genes were signifi-cantly down-regulated by ipafricept (e.g. AXIN2, LRP5/6, and FZD8). Conversely, in non-responsive tumors, these genes were either unchanged or up-regulated by the combination therapy. Histologic analysis revealed that total -catenin protein levels were reduced by ipafric-ept alone and in combination with paclitaxel in responsive tumors but were unchanged in non-responsive tumors. We are using these tumors to develop biomarkers that can be used clini-cally.Our data demonstrates the potential therapeutic benefit of targeting Wnt signaling in ovarian cancer. A Phase 1b clinical trial is currently examining ipafricept in combination with paclitaxel and carboplatin in patients with recurrent platinum-sensitive ovarian cancer.

    The Wnt/-catenin signaling pathway, which signals through the family of FZD receptors and several co-receptors, plays an important role in controlling cell differentiation, self- renewal, and maintenance of cancer stem cells.

    Antagonizing the WNT pathwat has demonstrated activity in Ovarian Cancer

    Ipafricept is a first-in-class fusion protein consisting of the extracellular ligand-binding domain of the FZD8 receptor and the Fc domain of a human IgG1 antibody. Ipafricept binds Wnt ligands and prevents them from binding to FZD receptors.

    Ipafricept (FZD8-fc, OMP-54F28) was generated at OncoMed Pharmaceuticals, Inc.

    The tumor biopsies were provided from Cooperative Human Tissue Network. Tumor xeno-grafts were initiated and propagated at OncoMed Pharmaceuticals, in NSG and NOD/SCID mice.

    For efficacy studies, treatments were initiated when tumors reached 100-200 mm3.

    For Limiting Dose Dilution (LDD) studies, single cell suspensions were depleted of H2KD/CD45 murine cells, diluted to appropriate cell doses and injected subcutaneously into NOD/SCID mice. Mice were followed up for up to three months. Cancer stem cell frequency was determined using L-Calc Version 1.1 software program (StemCell Technologies, Inc., Vancouver, Canada).

    In Vivo and Gene Expression data is illustrated as mean S.E.M.

    Responders to ipafricept + Taxol

    qRT-PCR of ipafricept + Taxol Normalized to Control Treatment Group

    FZD8extracellular

    (Wnt binding)domain

    ImmunoglobulinFc domain

    Domain Structure

    Isolate tumors post-treatment Transplant 100, 1000 cells (n=10) Grow 78 days without treatment Calculate CSC Frequency based

    on tumor take rate

    Ipafricept Reduces the Cancer Stem Cell Frequency in Ovarian Cancer

    Day

    Tum

    or V

    olum

    e, m

    m3

    0 7 14 21 28 35 42 490

    500

    1000

    1500Control mAbipafriceptTaxolipafricept +Taxol

    Combinatorial Treatment Enhanced by Antagonizing the WNT Pathway with Ipafricept Prior to Taxanes

    Serial Passage of Treated Tumor Cells

    0 28 56 84 112 140 1680

    500

    1000

    1500

    2000

    Day

    Tum

    or V

    olum

    e, m

    m3

    Control mAbTaxolipafricept day1 + Taxol day1ipafricept day1 + Taxol day3

    Serous carcinoma OMP-OV19

    Serous carcinoma OMP-OV40

    INTRODUCTION

    MATERIALS and METHODS

    Control mAb Taxolipafricept ipafricept+ Taxol

    WNT Signaling Molecule LEF1Modulated by Ipafricept in Responsive Tumors

    ipafricept responsive tumor : Serous carcinoma OMP-OV40

    ipafricept non-responsive tumor : Serous carcinoma OMP-OV63

    0.5 1 1.5 2.0 Relative Quantity

    Color Key

    * = 10% FDR

    OM

    P-O

    V63

    non-

    resp

    onde

    rO

    MP-

    OV4

    0 re

    spon

    der

    0 28 56 84 112 140 1680

    500

    1000

    1500

    2000

    Day

    Tum

    or v

    olum

    e, m

    m3

    Mouse 1Mouse 2Mouse 3Mouse 4Mouse 5Mouse 6Mouse 7Mouse 8

    Serous carcinoma OMP-OV19 ipafricept day 1 + Taxol day 3

    individual measurements

    FZD1FZD2FZD3FZD4FZD5FZD6FZD7FZD8FZD10LRP5LRP6WNT2BWNT4WNT5AWNT6WNT7BWNT11AXIN2DKK3LEF1MYC

    OMP-OV19 OMP-OV38 OMP-OV40

    Ipafricept Downregulates WNT Pathway Genes in Ovarian Tumors

    Day

    Tum

    or V

    olum

    e, m

    m3

    0 7 14 21 28 35 42 490

    500

    1000

    1500

    Study DayStudy Day

    Tum

    or V

    olum

    e, m

    m3

    0 10 20 30 400

    500

    1000

    1500

    2000

    2500

    Tum

    or V

    olum

    e, m

    m3

    0 20 40 600

    500

    1000

    1500

    Control mAbipafriceptTaxolipafricept + Taxol

    Control mAb

    Serous carconima OMP-OV40

    Serous carcinoma OMP-OV38

    Serous carcinoma OMP-OV19

    Tum

    or V

    olum

    e, m

    m3

    0 20 40 600

    200

    400

    600

    800

    1000

    0 7 14 21 28 35 42 49 56 63

    500

    1000

    1500

    Tum

    or V

    olum

    e, m

    m3

    0 7 14 21 28 35 42 49 56 63

    500

    1000

    1500

    Tum

    or V

    olum

    e, m

    m3

    Serous carcinoma OMP-OV27

    Serous carcinoma OMP-OV16

    Serous carcinoma OMP-OV63

    Non-Responders to ipafricept + Taxol

    Control mAbipafriceptTaxolipafricept + Taxol

    Control ipafricept Taxol ipafricept + Taxol0.00

    0.01

    0.02

    0.03

    0.04

    (1/142) (1/104) (1/43) (1/737)

    Frequency of Ovarian Cancer Stem Cells

    CSC

    Pro

    porti

    on o

    fH

    uman

    Ova

    rian

    Cel

    ls(+

    SE)

    Day Day

    Day

    Day

    Day