731ES13PR06393-01

Citocinas y proteínas de control inmune (CTLA y PD). Biología

y mecanismo de acciónRafael Sirera Pérez

Hospital General Universitario.Valencia

• The treatment of cancer by harnessing immune responses has long been pursued.

• To turn on the immune system against cancers have led to anecdotal successes:

– Tumor vaccines.

– Immune-stimulating cytokines such as interferons and interleukins.

– Intratumor injections of bacterial products to induce local inflammation and recruit an antitumor immune response.

– Ex vivo:

• Dendritic cells.

• Adoptive transfer: LAK ACT.

Cancer immunology

Theranosticstherapeutics

and diagnostics

Targeted

PersonalizedTaylored

Customized

Immunological cancer Rx

Inmunologic Reagents Approved by the Food and Drug Administration for Cancer Therapy

But, sometimes we loseWHY

• Boost immunity.

• Vaccination.

A fight between immune cells and cancer

• Failure to activate specific T cells:– Inadequate antigen processing/presentation.– Insufficient T-cell repertoire.– Available T cells below activation threshold set point.

• Ineffective T-cell differentiation into effector cells.

• Lack of homing of primed T cells to tumor sites.

• Immunosuppression in tumor microenvironment:– CTLA-4 on T cells (inhibitory receptor).– PD-1 on T cells (binds PD-L1 on tumor cells).– T-cell anergy (deficient B7 costimulation).– CD4+CD25+FoxP3+ Tregs (extrinsic suppression).– Indoleamine-2,3-dioxygenase (IDO tryptophan catabolism).

• Unbalance of cytokines.

Tumor escape of immunesurveyance

Gajewski, et al. 2007; Zou. 2005.

Theoretical reasons for failure of immune system to prevent cancer

outgrowth

APC = antigen presenting cell.

T cell

CD4

TCR/CD3complex

CD28

APC MHC class II

B7.1 or

B7.2

Immune “checkpoints”.

Autoimmunity.

Anergy.

CD80/CD86

Avoid autoimmunity, not react against environmental antigens.Ends reactivity and permit homeostasis.

The two signal for T cell priming

Janeway, et al. 1996; Topalian, et al.

The third signal for T cell priming by APC

The balance between positive and negative signals determines the

nature of the functional response

Leibson PJ. Curr Opinion Immunol. 2004.

The CD28/B7 costimulatory molecule families

CD28 and B7 protein family sequence alignments Grant EP. Semm Immunol.Chambers CA. Trends Immunol.

Signal transduction

No signal transduction

The fourth signal for T cell priming. Inhibitory costimulation

Induction of the B7-H1/PD-1 pathway may represent an adaptive immune resistance mechanism exerted by tumor cells in response to endogenous antitumor activity and may explain how melanomas escape immune destruction despite endogenous antitumor immune responses.

Induction of the B7-H1/PD-1 pathway may represent an adaptive immune resistance mechanism exerted by tumor cells in response to endogenous antitumor activity and may explain how melanomas escape immune destruction despite endogenous antitumor immune responses.

Induced expression of PD-L1 (B7-H1) on melanoma cells by

infiltrating T cells

• Heterogeneous group of membrane proteins that transmit inhibitory signals into the cell upon binding to their respective ligands:

– The CD28 family.

• PD-1, CTLA-4 and BTLA.

– The killer cell lectin-like (KLR) family.

• KLRG1.

– The T cell immunoglobulin.

• 2B4, LAG3 and CD160.

– Mucin domain (TIM) family.

• TIM-3.

Redundancy of inhibitory receptors (iRs)

• The receptors: – PD-1 (Programmed cell Death 1), – CTLA-4 (Cytotoxic T-Lymphocyte Antigen 4) and – Galectins,– CD69, – AhR (Aryl hydrocarbon Receptor).

• Or the intracellular: – Enzyme IDO (indoleamine 2,3-dioxygen-ase).– SOCS.– GADD45 (Growth Arrest and DNA Damage-inducible 45).

Immunoregulatory molecules are master regulators of inflammation

during the immune response

Ribas A. NEJM. 2012.

Blockade of CTLA-4 signaling in tumor immunotherapy, ipilimumab

Rudd CE, Immunol Rev. 2009.

CD28 and CTLA-4 coreceptor expression and signal transduction

CTLA-4 and PD-1 target distinct signaling molecules

Programmed death ligand 2 in cancer-induced immune suppression

• PD-L1 is expressed on many different cells.

• PD-L2 is expressed exclusively on DCs and monocytes.

• PD-1/PD-L1 interactions have been shown to play a substantial role in regulating autoreactive T cells.

• PD-L2 has been shown to be critically involved in regulating immune responses to environmental antigens.

Ligand-ligand interaction.

CD80 signal transduction.

CD80 expressed in DCs & T.

Topalian SL. Curr Opininio Immunol. 2012.

Anti-PD-1 and anti-B7-H1/PD-L1antibodies (mAbs) might behave differently owing to their ability to block distinct sets

of inhibitory interactionsPD-L1 = B7-H1 = CD274PD-L2 = B7-DC = CD273

• T-cell stimulatory cytokines has been a goal of translational immunologists since the discovery of IL-2 in the 1980s.

• In contrast to the successes obtained in murine models in which cytokine administration can lead to the complete eradication of bulky disease, the results of human clinical trials have been more modest: High-dose IL-2 therapy leads to significant tumor shrinkage in about 15% of patients with stage IV melanoma or renal cell cancer.

• The immune system is populated with inhibitory mechanisms that act to brake the specific immune response:

– Deactivators of cytokine signal transduction (e.g., suppressor of cytokine signaling proteins).

– Cell-to-cell inter-actions involving the binding of ligands on antigen-present-ing cells to t-cell inhibitory receptors (PD-1 and CTLA-4).

– Distinct cellular compartments that have potent immune-suppressive properties (regulatory T cells and mye-loid-derived suppressor cells; refs. 3–6).

Cytokines

• As IL-2, IL-15 stimulates cytotoxic activity of lymphocytes but unlike IL-2, it does not activate regulatory T lymphocytes.

• Do not leakage syndrome.

Carsom WE. CCR. 2010.

IL-15 vs. IL-2

Anti-TGF-βinhibiting immunosuppressive cytokines

T cell targets for immunoregulatory antibody therapy

Antibodies targeting immune costimulatory or coinhibitory molecules

• ANTAGONISTIC ANTIBODIES TO IMMUNE CO-INHIBITORY MOLECULES

• AGONISTIC ANTIBODIES

CD40 Activation of CD40 by ligand binding promotes B-cell and T-cell activation and stimulates apoptosis and growth of tumor cell

4-1BB (CD137)

an inducible costimulatory receptor expressed on various activated immune cells such as T cells. CD137 delivers anti-apoptotic signals, prevents T-cell death and can enhance antigen-specific T-cell activity

OX-40 (CD134)

a co-stimulatory receptor, transiently expressed on activated CD4 and CD8 T cells. CD134 regulates T-cell function and survival. enhances cytokine production and augments proliferation of both CD4 and CD8 T cells

• Mechanisms of tumor cells:– Antigen loss.

– Production and release of immunosuppressive factors.

– Antiapoptotic molecules.

• Factors in the tumor microenvironment:– Regulatory T cells (Tregs).

– Tolerogenic DCs.

– Tumor associated macrophages (M2).

– Myeloid-derived suppressor cells.

– Cancer-associated fibroblasts.

That’s not all, folks!!The other two main stumbling blocks for

anticancer therapy

• Improved understanding of the interaction between the tumor and the host immune system will result in advances in clinical care.

– An extensive and redundant types of inhibitory:

• Receptors.

• Proteins secreted or in cytoplasm.

• Cells.

• The cellular and molecular circuitries underlying the induction of adaptive immunity by mAbs remain poorly understood:

– relate to the Fc receptor:

• some cancer cell types express functional Fc receptors (buffering).

• the genes coding for human Fc receptors are very heterogeneous and all of them present multiple polymorphisms.

Challenges and future directions I

Challenges and future directions I

• Selection of patients may be expected to be the best candidates for therapy. Predictive markers.

• Monitoring of immunological parameters of patients undergoing therapy.

• We need immunologic biomarkers of prognosis.

• Future efforts should include the rational combination of checkpoint inhibitors with targeted therapies, other immune agents or chemotherapy.

LAB. ONCOLOGÍA MOLECULARCarlos CampsEloisa JantusAna BlascoElena SanmartínSandra GallachMarta UsóLuz García

Data ManagersVicente CastellanosBelén VázquezMarta AguilóEva Marqués

SERVICIO ONCOLOGÍA MÉDICACarlos CampsAlfonso BerrocalAna BlascoMa. José SafontCristina CaballeroMa. José GodesVega Iranzo Cristina HernandoNieves Martínez

ANATOMÍA PATOLÓGICAMiguel Martorell

CIRUGÍA TORÁCICARicardo GuijarroAntonio ArnauSantiago Figueroa

Rafael Sirera

Biotechnology students

Acknowledgment

1. Estamos de acuerdo en la necesidad de conocer mejor como se destruyen las células tumorales y qué nuevos infiltrados inmunológicos se dan tras las terapias inmunes antitumorales. Nos lleva a establecer nuevos criterios objetivos de respuesta al tratamiento más allá de RECIST.

2. Creemos adecuado poder seleccionar a los pacientes para poder administrar los fármacos a los mejores candidatos, los únicos capaces de responder a esta targeted therapy. ¿Cambiará eso las tasas de respuesta y supervivencias?

3. ¿Por dónde buscar los marcadores de respuesta predictivos para las terapias inmunológicas?

4. ¿Serán necesarias las combinaciones de diversos tratamientos targeted de índole inmunológica? ¿Asociados a la quimioterapia?

Debate