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 Tumorbinding 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) S U R V I V A L TIME From Slamon et al., N Engl J Med 344:783-92, 2001
Cetuximab (Erbitux) Plus Chemotherapy in Patients with Advanced Non-small-cell Lung Cancer S U R V I V A L TIME Kaplan-Meier estimates of overall survival time in the intention-to-treat population Robert Pirker et al, Lancet, Volume 373, Issue 9674, 2009, 1525 1531
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
Cytotoxic T cells can Recognize and Kill Tumor Cells T cell Cytotoxins Cancer T cell (green) identifies and binds to a cancer cell (blue), then releases packets of cytotoxic enzymes (red) to kill the cancer cell. T cell Cytotoxins Side view, from the interface between the T cell and cancer cell. The T cell can kill the cancer cell by releasing cytotoxins onto its surface. Source: Cambridge University
Another Early Approach: Using Dendritic Cells (DCs) to Stimulate T cell Mediated Antitumor Immunity
CD11c+ DCs are Present in Blood and Most Tissues A Blood DC Skin Langerhans cells B C Heart DC D Kidney DC Murine Tracheal DC Rat Tracheal DC Human Bronchiole DC E F G
Dendritic Cell (DC) Based Immunotherapy Circa 1992 Rationale: DCs are powerful antigen (Ag)-presenting cells Goal: Induce anti-tumor immunity using autologous DCs 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 Leukapheresis DC Generation Tumor Ag Ag loading/activation Immune & Clinical Monitoring Vaccination Ag-Loaded DCs
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
DC Vaccination for the Treatment of Metastatic Prostate 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 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; Braf V600E /Pten lox/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 hostrestricted 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.
Mass Cytometry and New Informatics Tools Enable Detailed Analysis of the Immune System Flow Cytometry Mass Cytometry 138 143 148 153 158 163 168 173 178 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 Day 3 Day 8 Adapted from Spitzer, et al., Cell 168:487 502, 2017
Immune Cell Proliferation is Sustained in the Secondary Lymphoid Organs and Blood throughout an Effective Immune Response Day 3 Day 8 Adapted from Spitzer, et al., Cell 168:487 502, 2017
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-CA209971 NIH Grant # R01-CA196657 DoD Award # W81XWH-15-1-0037