Reprogramming Tumor Associated Dendritic Cells for Immunotherapy Edgar Engleman, M.D. Professor of Pathology and Medicine Stanford University
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