Reprogramming Tumor Associated Dendritic Cells for ...€¦ · tumor cells to DCs via their Fc receptors. •Once activated, the DCs ingest, process and present multiple tumor antigens

Reprogramming Tumor Associated Dendritic Cells for Immunotherapy

Edgar Engleman, M.D.

Professor of Pathology and Medicine

Stanford University

Disclosures:

• Founder of Dendreon, a biotechnology company that developed autologous dendritic cell (DC) cancer immunotherapy (Sipuleucel-T/Provenge)

• Founder of Bolt Biotherapeutics, a biotechnology company developing therapeutic agents that reprogram tumor associated myeloid cells

An Early Approach: Immunotherapy with Tumor-binding mAbs

• mAbs recognizing tumor associated antigens or molecules that support their growth

• Each mAb recognizes only a single molecular target

• Can work by initiating tumor cell killing or inhibiting growth promoting signals

• Standard treatment for several types of tumors, e.g., breast cancer (anti-Her2), colorectal and head and neck cancers (anti-EGFR), GBM/colorectal/ovarian/lung (anti-VEGF-A), B cell lymphoma (anti-CD20)

Survival of Breast Cancer Patients Who Receive Chemotherapy Alone vs. Chemotherapy plus Trastuzumab (Herceptin)

From Slamon et al., N Engl J Med 344:783-92, 2001

SURVIVAL

TIME

Kaplan-Meier estimates of overall survival time in the intention-to-treat population

Cetuximab (Erbitux) Plus Chemotherapy in Patients

with Advanced Non-small-cell Lung Cancer

Robert Pirker et al, Lancet, Volume 373, Issue 9674, 2009, 1525–1531

SURVIVAL

TIME

Tumor-binding mAbs: Advantages and Challenges

• Advantages

- Cost effective manufacturing

- Widely applicable (“one size fits all”)

- Generally safe and well tolerated

• Challenges

- Limited efficacy as monotherapy

- mAb-drug conjugates and bispecific

mAbs are more potent

T cell (green) identifies and binds to a cancer cell (blue), then releases packets of cytotoxic enzymes (red) to kill the cancer cell.

Source: Cambridge University

T cellCytotoxinsCancer

Side view, from the interface between the T cell and cancer cell. The T cell can kill the cancer cell by releasing cytotoxinsonto its surface.

T cellCytotoxins

Cytotoxic T cells can Recognize and Kill Tumor Cells

Another Early Approach:

Using Dendritic Cells (DCs) to

Stimulate T cell Mediated Anti-

tumor Immunity

DC

Skin

Langerhans cells A B

GFE

Heart DC Kidney DC

Murine Tracheal DC Rat Tracheal DC Human Bronchiole DC

Blood DC

CD11c+ DCs are Present in Blood and Most Tissues

Dendritic Cell (DC) Based ImmunotherapyCirca 1992

• Rationale: DCs are powerful antigen (Ag)-presentingcells

• Goal: Induce anti-tumor immunity using autologousDCs loaded with tumor Ag

• Methods

• Generate DCs in vitro from circulating precursors

• Load DCs with Ag and induce their maturation

• Return Ag-loaded DCs to patients

Preparation and Administration of DC Vaccine

Ag-Loaded DCsVaccination

Leukapheresis DC Generation

Tumor Ag

Immune & Clinical Monitoring

Ag loading/activation

Stanford University Clinical Trials with Ag Pulsed DCs

• Non-Hodgkin’s Lymphoma

• Multiple Myeloma

• Prostate Cancer

• HIV Infection

• Colorectal Cancer

Complete Tumor Clearance in a Patient with Metastatic Colon Cancer

From: Small EJ et al. Placebo-controlled phase III trial of immunologic therapy with Sipuleucel-T

(APC8015) in patients with metastatic, asymptomatic hormone refractory prostate cancer. J Clin

Oncol 24:3089-94, 2006

DC Vaccination for the Treatment of

Metastatic Prostate Cancer

DC Vaccines: Advantages and Challenges

• Advantages

- Well tolerated

• Challenges

- High cost and complexity (“personalized”)

- Modest efficacy as monotherapy

Reprogramming Tumor DCs with a Combination of Tumor-binding

Antibodies + DC Stimuli

Loading and Activating Tumor-associated DCs In Situ: Summary of Published Findings*

• Tumor-binding antibodies can initiate a multistep process

that results in potent anti-tumor immunity by “bridging”

tumor cells to DCs via their Fc receptors.

• Once activated, the DCs ingest, process and present

multiple tumor antigens to T cells, which proliferate and kill

the tumor cells throughout the host.

• This approach eradicates pancreatic, lung, breast and

melanoma tumors in mice.

*from Carmi et al., Nature 521:99-104, 2015

Injection of Lewis Lung Tumor with alloIgG + CD40L/TNF Induces Complete Tumor

Regression

Eradication of Primary Breast CA and Lung Metastases

Carmi et al Nature 521:99-104, 2015

AlloIgG+TNF/CD40L Induces Complete Responses in Tyr:CreER; BrafV600E/Ptenlox/lox Melanoma

Carmi et al Nature 521:99-104, 2015

Mechanism of Action: Tumor-binding IgG Combined with DC Stimuli

Delivery Activation Eradication

1. Delivery: Anti-tumor antibody binds tumor cells and facilitates their delivery to DCs.

2. Activation: Activated DCs ingest tumor cells and present multiple host-restricted tumor Ags to T cells.These tumor Ags bear no relationship to the antibody-bound Ag(s).

3. Eradication: Tumor-specific T cells multiply and kill tumor cells throughout the body.

Tumor-binding IgG + DC Stimuli: Advantages and Challenges

• Advantages High potency against diverse tumors (in mice)

Induce immunity against many tumor antigens, including host-restricted antigens

Active against tumors that are resistant to checkpoint blockade

• Challenges

How to deliver multi-component therapy to the TME

Create tumor-targeted antibodies that retain DC loading and

adjuvant functions

Identifying the Determinants of Effective Immunotherapy

• Is efficacy dependent solely on the immune response and immune cell content in the tumor, or is a system-wide response required?

• What types of immune cells are required for efficacy?

• What are the causes of resistance?

• To investigate these questions we developed a method that enables organism-wide analysis of the immune system.

Flow Cytometry

Mass Cytometry and New Informatics Tools Enable Detailed Analysis of the Immune System

138 143 148 153 158 163 168 173 178

MassCytometry

Replacing light with mass enables significantly more multiplexing and provides a powerful new experimental tool for “systems immunology”.

Analysis of 40-100 proteins per cell in billions of cells requires new informatics tools in order to reveal differences between individuals and tissues, or changes in an individual over time.

Identifying the Factors Associated with Effective Cancer Immunotherapy

Spitzer et al., Cell 168:487–502, 2017

Blockade of Systemic Immunity Prevents Effective Therapy

Spitzer et al., Cell 168:487–502, 2017

Immune Cell Proliferation is Not Maintained in the Tumor Microenvironment During Tumor Rejection

Adapted from Spitzer, et al., Cell 168:487–502, 2017

Day 3 Day 8

Immune Cell Proliferation is Sustained in the Secondary Lymphoid Organs and Blood throughout an Effective

Immune Response

Adapted from Spitzer, et al., Cell 168:487–502, 2017

Day 3 Day 8

Systemic Activation of a CD4+ T cell Subset Mediates Anti-tumor Immunity

Hallmarks of Effective Immunotherapy

➢Effective immunotherapy generates a coordinated

systemic anti-tumor immune response that

involves sites (blood, bone marrow and lymphoid

organs) both near and far from the tumor.

➢This systemic immune response persists long after

immune cell activation in the tumor has ceased and

is required for efficacy.

➢CD4 T cells play a key role in efficacy.

Spitzer et al., Cell 168:487–502, 2017

Summary and Conclusions

• The most effective immunotherapies rely on tumor-attacking T cells,

generated as part of a coordinated system-wide immune response

that relies on many cell types and the molecules they produce.

• In the future, immunotherapy will be comprised of combinations of

products that engage different components of the immune response.

• Delivering immunomodulatory agents to the TME is one such

combinatorial approach.

• The analytical tools (mass spectroscopy, algorithms) described here

can be used to reveal the effects of any disease or intervention on the

immune system.

NIH Grant # U54-CA209971NIH Grant # R01-CA196657DoD Award # W81XWH-15-1-0037