THE USE OF BIOMARKERS FOR

TREATMENT DECISIONS IN

ONCOLOGY

Angelica Fasolo, MD and Cristiana Sessa, MD

Montabone Unit for New Drugs Development

Istituto Nazionale Tumori Milano, Italy

Definition of a biomarker

� “Characteristic objectively measured and evaluated as indicator of normal biological processes, pathogenic processes or pharmacologic responses to a therapeutic intervention.” (US National Institutes of Health Biomarkers Definition Working Group)

� Key component of translational research.

Biomarkers Definitions Working Group (2001) Clin Pharmacol Ther 69:89-85

Translational research in new drug development

Transfers preclinical research into clinical practice through subsequent steps:

� study of the biology of the disease

� evaluation of the biological effects of the drugs in animals

� study of the biological effects of those drugs in humans

Molecular target

Molecule or pathway with causal relationship with tumor

transformation and progression which can be identified

on tumor tissue.

Download Figure 1

Biomarkers and drug development

� Used during the subsequent steps of drug development in order to:

� define the target deregulation correlate to tumor development (proof of

target)

� verify the interaction between the drug and the target or pathway (proof

of principle)

� verify that alteration of a specific target is crucial for a specific tumor in

humans (proof of concept)

� verify that the interaction between drug and target is responsible for

biological effects (proof of activity)

� screen and optimize candidate agents

� define a range of doses

� provide rationale for combination therapies

Park JW et al. Clin Cancer Res 2004;10:3885-3896

Biomarkers classification

Three main categories (US-NCI) :

A. Prognostic biomarkers

B. Predictive biomarkers

C. Pharmacodynamic biomarkers

Kellof GJ, et al. Clin Cancer Res 2004;10:3881-3884Sawyers CL Nature 2008;452:548-552

A. Prognostic biomarkers

� Correlate with clinical outcome and allow prediction of the natural course of cancer.

� Guide the therapeutic decision.

They include:

1. Biological progression markers

2. Risk biomarkers (or screening biomarkers)

A. Prognostic biomarkers

1. Biological progression markers

� Measures of tumor activity (CEA, alphaFP, PSA, CA-125, hCG).

� Often used to monitor the effects of therapy because they could be modulated by the effect of the drug but are not implicated in neoplastic progression.

A. Prognostic biomarkers

2. Risk biomarkers (or screening biomarkers)

� Describe risk of cancer occurrence or cancer progression because they are implicated in neoplastic progression and include:

1. carcinogen exposure

2. genetic predisposition (e.g., BRCA1/2)

3. over expression of genes (e.g., PTEN, BCR-ABL, HER-2/neu, RAS, AKT)

4. pharmacogenomic parameters (genetic polymorphisms, DNA methylation,

aneuploidy)

5. environmental factors and lifestyle (e.g., HPV or HBV infection, tobacco use)

6. multifactorial risk models (e.g., Gail model, Oncotype DX, MammaPrint)

B. Predictive biomarkers

� Correlate with probability of clinical response to treatment:

� amplification of the gene HER-2 in breast cancer for treatment with anti-

HER-2

� ER/PgR expression in breast cancer for hormonotherapy

� presence of Philadelphia chromosome (BCR-ABL fusion gene) in

leukemia for anti-BCR-ABL

� mutations of EGFR in lung tumors for anti-EGFR

� mutations in KRAS in patients failing EGFR-specific therapy

� mutations of EGFR and intact PTEN after failure of anti-EGFR in

glioblastoma multiforme

C. Pharmacodynamic biomarkers

� Correlated to biological and clinical effects of the drug on the tumor.

� Measured in serum, circulating cells, saliva, urine or tissue biopsies.

They could be:

1. lower expression or activity of a molecular target (e.g., EGFR tyrosine

kinase inhibition)

2. induction of metabolism (e.g., interference with cytochrome P-450)

3. interference with cell growth processes (e.g., Ki-67, BCL-2, cytokeratins)

4. vascularization and metabolism (imaging biomarkers)

Sarker D et al. Biomarkers Med 2007;1:399-417

“Proximal” and “Distal” biomarkers

� Proximal: reflect the immediate effect of the drug on its target (e.g., decrease in a protein substrate of phosphorylation downstream the target kinase).

� Distal: reflect the effect of the drug downstream the molecular target (e.g., Ki-67 expression for reduction in proliferation).

Applications of biomarkers in drug

development

1. Target discovery and validation

2. Preclinical studies

3. Phase 0 clinical studies

4. Phase I and II clinical studies

1. Applications of biomarkers in drug

development: Target discovery and validation

� Identify targets for therapy

(e.g., HER-2, VEGF, VEGFR, BCR-ABL, ras…):

� HER-2 amplification in breast cancer for anti-HER-2 therapy

2. Applications of biomarkers in drug development preclinical studies

� Selection of animal models and lead compounds to test

� Definition of mechanisms of action in vitro and in vivo

� Prediction of the effects of drug combinations

3. Applications of biomarkers in drug development: Phase 0 clinical studies

� Conducted before phase I, in a maximum of 10 patients, with no therapeutic or diagnostic intent.

� To define pharmacodinamically effective dose during a limited exposure (usually 1 week) to the drug.

� Relevant in the go versus no-go decision-making process of going into clinics.

� Crucial for defining pharmacology, bioavailability, pharmacodynamics and metabolism of microdoses of the drug.

3. Applications of biomarkers in drug

development: Phase 0 clinical studies –an example

� Phase 0 of the oral poly(ADP-ribose)polymerase (PARP) inhibitor, ABT-888.

� To determine a dose range and time course over which ABT-888 inhibits PARP activity in tumor biopsies and PBMCs; to study thepharmacokinetics of ABT-888.

� Starting dose for phase I selected on the bases of PARP inhibition in tumor biopsies and PBMCs.

Kummar S et al. J Clin Oncol 2009;16:2705-11

PARP-1 is a key enzyme involved in the repair of single-strand DNA breaks

PAR chains

are

degraded

via PARGRepaired

DNA

PARPDNA damage

Binds directly

to SSBs

Repair enzymes

PAR

Nicotinamide

+pADPr

NAD+

Once bound to damaged DNA, PARP modifies itself producing large branched chains of PAR

Illustration courtesy of AstraZeneca

4. Applications of biomarkers in drug development: Phase I clinical studies

� Evaluate toxicity of a new compound and select optimal dose for subsequent efficacy trials, once defined the MTD.

� For cytotoxic agents greater drug exposure corresponds to a greater tumor-cell kill in preclinical models.

� For molecular targeted drugs a greater selectivity inhibits specific tumor factors with reduction of toxicity.

4. Applications of biomarkers in drug development: Phase II clinical studies

� Collection of tissue samples and performance of molecular analyses to identify mechanisms responsible of biological effects.

� Could be used as surrogate endpoints of efficacy and prediction of clinical outcome to identify active drugs for phase III trials.

Application of biomarkers in Phase I clinical studies

� PARP inhibitors and cytotoxic agents

� PARP inhibitors and DNA damaging agents

� Everolimus (RAD001)

� Antivascular agents

Application of biomarkers in Phase I clinical studies: PARP inhibitors and cytotoxic agents

� Phosphorylated histone H2AX (γH2AX) initiates DNA repair process after double-strand breaks (DSBs) caused by radiotherapy and many cytotoxics.

� γH2AX detected by immunofluorescence in vitro system; as DSBs are repaired, the number of γH2AX foci per nucleus decreases.

� Changes of γH2AX foci reflect the activation of the DSBs repair processes.

� γH2AX is a potential pharmacodynamic marker of DNA damage in studies with radiotherapy and PARP inhibitors.

Bañuelos CA et al. Clin Cancer Res 2009;1 5:3344-3353Ashworth A. J Clin Oncol 2008;26:3785–90

Application of biomarkers in Phase I clinical studies: PARP inhibitors and DNA damaging agents

1. Phase 0 study: assesses PARP inhibition in PBMCs (pharmacodynamic endpoint) to define the 50% PARP inhibitory dose (PID) of AG014699 as starting dose for phase I.

2. Phase I study: to define the dose of Temozolomide (TMZ) and AG014699 that could be safely combined.

Plummer R, et al. Clin Cancer Res 2008;23:7917-7923

Download Figure 2

Application of biomarkers in Phase I clinical

studies: Everolimus (RAD001)

� Ribosomal protein S6 Kinase 1 (S6K1) and repressor of mRNA translation eukaryotic translation initiation factor 4E-Binding Protein (4E-BP1) as pharmacodynamic biomarkers for mTOR inhibitors.

� Divergent results because of different biomarkers of the same pathway (eIF-4G, 4E-BP1, S6K1) at different sites (PBMCs, skin, and tumor) can result in different optimal biologic recommended doses (RD).

� Pharmacodynamic biomarkers alone cannot allow the selection of the RD.

O’Donnell A, et al. J Clin Oncol 2008; 26:1588-1595Tanaka C, et al. J Clin Oncol 2008; 26:1596-1602Tabernero J, et al. “J Clin Oncol 2008; 26:1603-1610 Fasolo A, Sessa C. Expert Opin Investig Drugs 2008;11:1717-34

Download Figure 3

Application of biomarkers in Phase I clinical

studies: Antivascular agents

� Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) provides parameters of tissue perfusion and permeability affected by antivascular drugs.

� DCE-MRI as biomarker of 5,6-Dimethylxanthenone-4-acetic acid (DMXAA ) biological effects in phase I.

� Recommended dose for subsequent clinical development selected according to perfusion-related parameters.

Galbraith SM, et al. J Clin Oncol 2002;18:3826-3840

Download Figure 4

Conclusions

� Biomarkers are key components of translational studies, useful in the process of drug development of molecular targeted agents.

� Still too few cases in which the sufficient knowledge of the dynamic interaction between drug and target justifies a pharmacodynamically only driven strategy.

� Biomarkers are useful in the process of dose escalation, definition of schedule and doses for subsequent phase II studies.