Biology of Cancer Principles of Systemic Therapy

Immortality Invasion Loss of adherence Autocrine Somatic and genetic differences Implications for therapeutic approaches

Objectives Biology of malignancy Definition of Terms Principles of Systemic Therapy TNM Staging Classification Common Chemotherapy Agents Targeted Therapies Summary

Biology of Malignancy Round 1

Tumor Biology Principles of Cellular Growth Ability to produce exact replica –essential component of life Lack of fidelity in cellular reproduction –creates genetic instability Cancer is a disease: –abnormal regulation of cellular growth –reproduction Control of the cell cycle progression –how processes are altered in malignant cells

Cell Cycle-Mechanism Replication and division: –Functional phases precise copying of the DNA (S phase) regulation/ and segregation of chromosomes (M phase) –Preparatory phases: G1 ( preparation for S phase) G2 ( preparation for mitosis) Cells not actively dividing: –terminal differentiation –G0 (no cycling state) Events occur in orderly fashion Kinetics important in chemotherapy mechanisms

Cell Cycle Extra-cellular Signals Complex regulation and division not in a vacuum Cell integrate signals into control mechanisms: –Nutrient status –Cell to cell contact –Extra cellular peptides Growth factors cause cells in Go phase through cell cycle Continued growth factor exposure Cytokines: –soluble mediators of cell to cell communication –interleukins, interferon, CSF –bind to receptors on surface of cells –cascade of biochemical signals activation/suppressing of genes

Cell Cycle Check Points Events of cell cycle highly ordered: – different extra cellular/intracellular events Dependency controlled by: –regulation of gene products –mutations in checkpoints genes –progression through cell cycle Mutations result in altered responses: –environmental or therapeutic DNA damaging agents increased decreased cell death –increased mutation rate or –genetic instability

What Goes Wrong Potential mechanisms: –Cellular hypoxia (outgrow blood supply) –Decreased availability of nutrients –Alternation in cytokine/hormonal milieu –Accumulation in toxic metabolites –Inhibition of cell-cell contact

Life-cycle 1cm 3 - >1g tumor (10 9 ) cells –1 cm the limit of clinical detection –30 doublings occurred prior to clinical detection Only 10 more doublings (3 logs) –1kg of tumor –terminal disease Pre-clinical phase 75% of “life of tumor”

Cellular Proliferation of Tumors Heterogeneous as a result of: –variability in blood supply/nutrients –differing degrees of differentiation within clones –constant generation of new sub clones Increased volume as a result: –increased lifespan –Increased number –decreased death

Principles of Metastases Principle cause of death Mainly routes of dissemination: –via blood steam –lymphatic Are flow and organ specific Establishment of metastases is inefficient: –subpopulation/clone have the abilities to metastases –generally most malignant/aggressive

Steps in Metastatic Cascade Escape Travel through the blood/lymphatic system Arrest/attachment Establishment of clone

Metastases Escape May be biologically facilitated by: –ability to commit vascular invasion –cell necrosis –molecules of the cell surface –protease (enzyme) secretion by tumor

Travel Blood supply (angiogenesis) must be adequate Adequate lymphatic drainage Special circulatory circumstances

Principles of Cytotoxicity Relationship between dose and cytotoxicity: –exponentional –drug dose –number of cells at risk/at exposure Principles of therapy: –multiple courses of therapy –each treatment kills same proportion (not number) of cells –small decrease in drug dose results in large increase in cell survival –e.g.: 3 log killed to log regrowth between cycles

Gompertzian Growth Curve Log Kill Time Standard of Care ↓ Dose Delayed Schedule

Summary-Biology Cell Cycle kinetics: –highly ordered –critical for both normal as well as aberrant growth Relationship between dose & cell survival: –generally exponential –drug dosing –number of cells at risk for exposure Resistance result of the selection pressure: –instability of tumor –size of tumor Metastases: –flow and organ specific –escape/travel/arrest/establishment

Definition of Terminology Round 2

Principles of Systemic Therapy Definition of Terms Neoadjuvant: –prior to definitive surgery –advanced/locally advanced disease –organ preservation Adjuvant: –post surgical/pathological staging –statistical possibility of micrometastatic disease –efficacy of therapy in tumor site Metastatic: –Curable (testes) –Incurable (prostate, lung)

Continued Induction Chemotherapy: –setting of biopsy proven metastatic disease –may be curable (testes) –incurable (renal) Direct Instillation: –site directed installation or perfusion –primary target/organ (bladder) –sanctuary sites (brain)

Principles of Systemic Therapy Round 3

Principles of Combination Systemic Therapy Objectives: –biochemical interactions between drugs –maximum cell kill as tolerated by host –broader range of coverage of resistant cell lines –slows development of resistant cell lines Optimum dose and schedule

Gompertzian Growth Curve Log Kill Time

Mechanisms of Resistance Drug exposure/Selection pressure –chemotherapeutic agents selects for resistant cells –Goldie-Coldman hypothesis Resistance within a tumor a function of: –inherent genetic instability of a tumor –size of tumor ( # cells) Tumor sanctuaries

Toxicity of Chemotherapy

Meta-Analysis: CHF Anthracycline Dose Epirubicin (n=9144) Estimated probability of developing CHF 0.20 Doxorubicin (n=3941) Cumulative dose (mg/m 2 )

Functional Impairments Caused by Cancer Therapy

Summary Goal of therapy: –stage dependent –tumor type specific –incorporating host factors Selection of therapy: –single versus combination chemotherapy –combined versus single modality of therapy Toxicity of therapy: –overlapping/non-overlapping

Staging Principles TNM Classification Round 4

Staging Principles Stage I –Organ confinement Stage II –Organ plus regional lymph nodes Stage III –Locally advanced Stage IV –Metastatic

Common Chemotherapeutic Agents Round 5 Drug Classification

Alkylating Agents Mechanism of Action: –disrupts DNA Indications: –tumors with low growth potentials –low grade lymphomas –number of sites where they can interact –dose important Agents include: –Metchlorethamine (MOPP) –Cyclophosphamide (CHOP/CMF/FAC/AC) –Chlorambucil (CLL/low grade lymphoma) Toxicity: –myelosuppression

Anti-tumor Metabolites Mechanism of action: –topoisomerase inhibitor (breaking coiling strands) –free radical formation Indications: –Breast cancer –Hodgkin's Disease Agents: –Adriamycin, Epirubicin, Mitozantrone (FAC) –Bleomycin (ABVD) Toxicity: –myelosuppression –pulmonary fibrosis –Left ventricular dysfunction

Anti-tumor Metabolites-2 Mechanism of action: –substitutes a metabolite into the DNA/RNA Indications: –Colon cancer (5FU-FA) –Breast cancer (CMF) Agents: –5FU –Methotrexate –Capecitabine –Gemcitabine Toxicity: –mucositis –myelosuppression

Vinca Alkaloids Mechanisms: –inhibits microtubule formation during M phase Indications: –Lung cancer (vinorelbine) –Lymphomas (vincristine) Agents: –Vincristine (CHOP) –Vinblastine –Vinorelbine (Cisplatin/Vinorelbine) Toxicity: –myelosuppression –neuropathy

Antimicrotubule Mechanism of Action Inhibition of Polymerization: Inhibition of Depolymerization: MicrotubuleTubulin   docetaxel paclitaxel vinblastine vinorelbine Vinca alkaloids

Other Agents-Cisplatin Mechanism: –Interferes with DNA replication without affecting normal RNA and protein synthesis Indications: –Lung Cancer (Cisplatin/vinorelbine) –Ovarian Cancer (Cisplatin/taxol) Analogues: –Carboplatin –Oxaloplatin Toxicity: –myelosuppression –neuropathy

Cisplatinum ® Mechanism of action Pt – Herceptin ® + Herceptin ®  DNA repair, reversal of resistance PtPt Pt PtPt PtPt PtPt DNA repair/platinum resistance PtPt

Taxanes Mechanism: –Interfere with structure and function of the microtubules Indication: –Breast –Lung –Ovarian Analogues: –Taxol (TAC) –Taxotere Toxicity: –myelosuppression –neuropathy

Summary Common Agents Agents may be: –cell cycle dependent or independent –oral or intravenous –bolus or continuous infusion Specific toxicities: –nonoverlapping/overlapping –facilitate combination chemotherapy

Targeted Therapies Round 6 Receptors HER-2 proteins Antiangiogenesis

Treatment Options for Women with HER2 Positive Breast Cancer “The Herceptin Story”

HER-2 Terminology  H uman E pidermal Growth Factor R eceptor- 2  HER2/neu-2  oncogene encoding production  HER2 receptor  Also known  neu (rat gene)  c-erbB-2

erb-b1 EGFR HER1 neu Erb-b2 HER2 Erb-b3 HER3 Erb-b4 HER4 TGF  EGF HRG (NRG1) Epi  -cel HB- EGF Amp Epi HB-GF NRG1 NRG2 NRG3 NRG4 Tyrosine kinase domain Ligand binding domain Transmembrane The EGFR/HER Family

Targets HER2 protein High affinity (K d = 0.1 nM) High specificity  95% human, 5% murine  Decreases potential for immunogenicity HER2 epitopes recognized by hyper variable murine antibody fragment Human IgG-1 Trastuzumab: Humanized Anti-HER2 Antibody

Transmembrane Structure of HER2 Receptor Extracellular domain (632 amino acids) Ligand-binding site Intracellular domain (580 amino acids) Tyrosine kinase activity Transmembrane domain (22 amino acids) Cytoplasm Plasma membrane

HER2 Receptor Transmembrane Signal Transduction Pathway Signal transduction to nucleus Nucleus Binding site Tyrosine kinase activity Cytoplasm Plasma membrane Growth factor Gene activation CELL DIVISION

Role of HER2 in Breast Cancer  A HER2-positive status:  predictor of poor prognosis  multivariate analysis HER2 was a strong independent predictor: relapse (p=0.001) overall survival (p=0.02)  The HER2 receptor provides:  Extracellular target specific anticancer treatment  Herceptin Slamon DJ et al. Science 1987;235:177–82

Indicators of Increased HER2 Production 1 =  gene copy number 2 =  mRNA transcription 3 =  cell surface receptor protein expression 4 =  release of receptor extracellular domain A = HER2 DNA B = HER2 mRNA C = HER2 receptor protein NormalAmplification/overexpression Nucleus Cytoplasm Cytoplasmic membrane C B A

Disease-Free Survival 87% 85% 67% 75% NEvents AC  T AC  TH % HR=0.48, 2P=3x AC  TH AC  T Years From RandomizationB31/N9831

Angiogenesis This concept first put forward by Folkman VEGF one of the most important mediators Endothelial cell specific mitogen Interacts with VEGFR-1 and VEGFR-2 Essential for normal embryonic vasculogenesis

Vascular Endothelial Growth Factor (VEGF) Transformed cell lines secrete VEGF VEGF mRNA : –high levels in many human tumours Increased microvessel density –poor prognostic factor VEGF felt to be: –major tumour angiogenesis factor in epithelial cancers

VEGF VEGFR - 2 Cell membrane Tyrosine Kinase Signal Transduction

VEGF VEGFR - 2 Cell membrane Tyrosine Kinase Signal Transduction X X (1) X (2) X (3)

Inhibiting Angiogenesis Deplete VEGF Block VEGF receptor: –Extracellular = monoclonal antibodies –Intracellular = tyrosine kinase inhibitor Target immature endothelial cells

VEGF VEGFR - 2 Cell membrane Tyrosine Kinase Signal Transduction X (1)

Bevacizumab (Avastin) Humanized monoclonal antibody against VEGF: –Direct anti-angiogenic effect –Decreases vascular permeability Given via IV every two weeks Rare serious adverse effects: –Hypertension –Bleeding/Thrombosis Established benefit in CRC –Studies in renal, prostate and breast

Colorectal Cancer

Cetuximab (Erbitux) Monoclonal antibody targeting EGFR Blocks binding of ligand to the EGFR Leads to receptor internalization ADCC, complement activation Activity in: – colorectal cancer and SCCHN In vitro synergistic with radiation and chemo

VEGF VEGFR - 2 Cell membrane Tyrosine Kinase Signal Transduction X (2)

Inherited RCC –Von Hippel-Lindau syndrome –Germ line mutation of chromosome 3p Non-inherited RCC: –VHL gene tumor suppressor gene inactivation –Expression of oxygen-regulated transcription factor (HIFa) –Induction of hypoxia-inducible genes including vascular endothelial growth factor (VEGF) VEGF overexpression promotes tumor angiogenesis Biology of RCC

Mechanism of Action in RCC RCC pathogenesis and progression ↑ VEGF↑ PDGF Vascular permeability Cell survival, proliferation, migration Vascular formation, maturation Loss of VHL Protein Function VEGFRPDGFR VEGF PDGF Vascular Endothelial Cell Pericyte/Fibroblast/ Vascular Smooth Muscle Pericyte/Fibroblast/ Vascular Smooth Muscle

Mechanism of Action in RCC Inhibition of RCC pathogenesis and progression ↑ VEGF↑ PDGF Vascular permeability Cell survival, proliferation, migration Vascular formation, maturation Loss of VHL Protein Function VEGFRPDGFR VEGF PDGF Vascular Endothelial Cell Pericyte/Fibroblast/ Vascular Smooth Muscle Pericyte/Fibroblast/ Vascular Smooth Muscle Sunitinib Sorafenib Sunitinib Sorafenib

Lung Cancer Gefitinib & Erlotinib In initial phase I (safety) trials of gefitinib –patients with NSCLC responded This led to phase II trials: –Gefitinib (Iressa) –Erlotinib (Tarceva) Response rates: –10 – 15 % as single-agent –Females, non-smokers, adenocarcinoma –? More likely to respond if get a rash?

VEGF VEGFR - 2 Cell membrane Tyrosine Kinase Signal Transduction X (3)

Inhibition of Growth Signals Prototype drug is Imatinib: –Gleavec –Binds to the tyrosine kinase domain of the bcr-abl fusion protein in CML Leads to extremely high rates –complete responses –cytogenetic responses Also inhibits the TK of KIT, PDGFR

GIST GIST: –Rare –chemoresistant sarcoma Often has gain-of-function mutations in KIT –Leads to constitutive activation –Driving force in oncogenesis of this tumor Imatinib leads to prolonged: –durable remissions in the majority of pts –Must express express KIT

Putting it all Together …welcome to my world!! Knockout

Principles of Oncology Stage and cell type Additional Factors: –patient characteristics: age co-morbid conditions psychological profile –treatment related factors: treatment intent/curative vs palliative toxicity profile of therapy

Principles of Combination Systemic Therapy Objectives: –biochemical interactions between drugs –maximum cell kill as tolerated by host –broader range of coverage of resistant cell lines –slows development of resistant cell lines Optimum dose and schedule Optimum combination of therapeutic drugs

Summary Goal of therapy: –stage dependent –tumor type specific –incorporating host factors Selection of therapy: –single versus combination chemotherapy –combined versus single modality of therapy Toxicity of therapy: –overlapping/non-overlapping