Radiation Therapy as an Immunomodulator Yvonne Mowery, MD, PhD February 20, 2017 Tumor/Immune System Balance Kalbasi, JCI 2013
UNC-Duke-NC State-Wake Forest Spring 2017 2 RT Can Shift Balance Toward Elimination Kalbasi, JCI 2013 Radiation-Induced Immune Stimulation Exposure of new tumor antigens MHC-I expression chemokines à recruit cytotoxic T-cells TCR repertoire diversity death receptors à cytotoxic T-cell activity Abscopal effect Sharabi, Lancet Onc 2015
UNC-Duke-NC State-Wake Forest Spring 2017 3 Overview of Antitumor Immune Response Makkouk, Canc Res 2015 Immune Synapse Peptide-MHC T cell receptor Antiinflammatory Proinflammatory Grass, Curr Prob Canc 2016
Tumor-Immune Cell Interaction Ma, J Heme Onc 2016 CTLA-4 and PD-1 Immune Checkpoints Topalian, Nature Reviews 2016
RT Synergy with CTLA-4 and PD-1 Checkpoint Blockade in vivo RT = 20 Gy x 1 C4 = anti-ctla-4 Ab P1 = anti-pd-l1 Ab Proportion survival Proportion survival Days Syngeneic melanoma cell line (B16-F10) Twyman Saint-Victor, Nature 2016 CD8+ T-cells and Tregs with RT + Immune Checkpoint Blockade Treg CD8 Twyman Saint-Victor, Nature 2016
CD8+ T-cells Reinvigorated after RT and Immune Checkpoint Blockade Reinvigorated = GzmB + Ki67 + Exhausted = GzmB - Ki67 - Twyman Saint-Victor, Nature 2016 RT Increases T Cell Receptor Diversity Tumor Infiltrating Lymphocytes Broader TCR repertoire associated with clinical benefit to anti-ctla-4 TCR Twyman Saint-Victor, Nature 2016 Postow, J Immuno Cancer 2015
Optimal RT Timing Varies for Different Immunomodulatory Targets Young, PLOS One 2016 RT and Ipilimumab Timing in Metastatic Melanoma Ipi before RT Ipi after RT Qin, IJROBP 2016
Potential Impact of RT Fractionation on Immunologic Effect 9H10 = anti-ctla-4 Ab Primary Tumor Secondary Tumor TSA cell line (murine poorly immunogenic mammary carcinoma) Abscopal effect with fractionated RT only (8 Gy x 3 or 6 Gy x 5) No Abscopal effect with 20 Gy x 1 Dewan, Clin Canc Res 2009 Tumor-Specific Memory Response with RT + anti- CD40 agonist Murine lymphoma model (10 Gy) Tumor rechallenge for surviving mice from above (> 60 days after initial tumor) Dovedi, Cancer Imm Res 2016
Dendritic Cells and CD8+ T cells Required for Tumor Control by RT + anti-cd40 agonist Dendritic Cell Depletion (DT) abrogates response to RT + anti-cd40 CD8 T-cell depletion abrogates response to RT + anti-cd40 Dovedi, Cancer Imm Res 2016 RT Modifies the Tumor Microenvironment DAMP = dangerassociated molecular pattern Deloch, Frontiers Onc 2016
RT-Induced Immunogenic Cell Death Immunogenic cell death DAMP release/cell surface expression Calreticulin (CRT) ATP High-mobility group box 1 (HMGB1) Type I IFN Maturation of APCs Promotes Phagocytic Uptake Activation of Effector Immune Cells Cytoxic T Cell-Mediated Tumor Cell Lysis Grass, CurrProb Canc2016 RT-Induced Calreticulin à Increased Sensitivity to Cytotoxic T Lymphocyte (CTL) Lysis Non-Cancer Stem Cells Cancer Stem Cells CTL Lysis Assay CBP = Calreticulin Binding Protein LCMV = lymphocytic choriomeningitis virus peptide (negative control) Gameiro, IJROBP 2016
Radiation Induces T Cell Priming Without RT à Tolerance RT à Cross-Presentation à Immunity Spiotto, Sci. Imm. 2016 RT Activates Pro-Inflammatory Pathways Spiotto, Sci Imm 2016
RT Increases IFNb Production by Immune & Tumor Cells Tumor response to RT abrogated by IFN receptor knock-out Burnette, Canc Res 2011 RT Increases T cell Infiltration & Effector Response Spiotto et al, Sci Imm 2016
RT Effects on Tumor Microenvironment Promoting T cell Recruitment Vascular normalization secretion of chemokines à recruit CD8+ T cells Upregulation of MHC-I, Fas, ICAM-, natural-killer group 2 member D (NKG2D-L) on tumor cells à improved tumor cell killing Negative effect: PD-L1 on tumor cells Demaria, JAMA Onc 2015 Increased CD8+ T cells after RT and Synergy with anti-pd-1 Ab Sharabi, Cancer Imm Res 2015
Increased Immune Cell Infiltrate after RT Hematopoietic Cells Dendritic Cells Myeloid cell marker Dendritic Cell marker B16F1 tumors or tumors treated with 25 Gy local RT Burnette, Canc Res 2011 Tumor-Infiltrating Dendritic Cells (TIDC) from Irradiated Tumor Stimulate T Cell Proliferation T cell Proliferation Effect abrogated in IFN receptor knockout mice (KO) SIY = exogenous tumorassociated antigen Burnette, Canc Res 2011
UNC-Duke-NC State-Wake Forest Spring 2017 15 RT-Induced Abscopal Response Whiteside, Clin Canc Res 2016 Abscopal Response after RT + Ipilimumab SBRT (2-3 fractions) à 3-5 days à ipilimumab Twyman-Saint Victor, Nature 2015
UNC-Duke-NC State-Wake Forest Spring 2017 16 Abscopal Response after RT + Ipilimumab RT dose < 3 Gy associated with better response (81% vs. 52% favorable, p = 0.014) Chandra, Oncoimmunology 2015 Out-of-Field DNA Damage after RT g-h2ax foci in hair follicles outside of RT field Corresponding changes in plasma levels of certain cytokines: MDC/CCL22: secreted by macrophages and dendritic cells MIP-1a/CCL3: attract macrophages, monocytes, neutrophils Siva, Clin Can Res 2016
RT-Induced Complement Activation Involved in Tumor Control Green = C3 cleavage products Regal, Ann Tran Med 2016 Summary of Immune-Related Anti-Tumor Effects of RT Bernstein, Nature Reviews 2016
RT and Immunotherapy in T cell Negative Tumors Demaria, JAMA Onc 2015 RT and Immunotherapy in T cell Poor Tumors Demaria, JAMA Onc 2015
UNC-Duke-NC State-Wake Forest Spring 2017 19 Ongoing studies investigating RT combined with tumor vaccines, CAR T cells, immune checkpoint blockade, immune costimulatory agonists Whiteside, Clin Canc Res 2016 RT Induces Pro- & Anti-Immune Signals Immunosuppressive aspects of RT can counterbalance immunemediated tumor control Demaria, JAMA Onc 2015
UNC-Duke-NC State-Wake Forest Spring 2017 20 RT Fractionation: Pro-Inflammatory Effects Deloch, Frontiers Onc 2016 RT Fractionation: Anti-Inflammatory Effects RT-induced lymphocyte death Increased Tregs Release of immunosuppressive cytokines Upregulation of immune checkpoint molecules (e.g. PD-L1) Deloch, Frontiers Onc 2016
Summary RT à pro-inflammatory tumor microenvironment Immune cell infiltration Immunogenic cell death à DAMPs à APC activation Cross-presentation of tumor antigens Complement pathway activation Reinvigorates exhausted T cells and TCR diversity RT can also have anti-inflammatory effects Importance of dose and timing with combined therapy RT à out-of-field tumor effects (Abscopal effect) Particularly combined with other therapies