FRONTIERS IN TUMOR MARKERS

Robert C. Bast, Jr., M.D.

U.T. M.D. Anderson Cancer Center

October 16, 2006

FRONTIERS IN TUMOR MARKERS:

CA 125 FOR ACCELERATING DRUG EVALUATION IN OVARIAN CANCER

THE CHALLENGE OF TARGETED DRUG DEVELOPMENT

• More than 400 New Drugs are Being Developed for Clinical Trials

• Many Targeted Drugs will be Effective Only in Combination

• Less than 4% of Cancer Patients Enter Clinical Trials

• Less than Half of Ovarian Cancer Patients meet RECIST Criteria

• Many Targeted Drugs will be Cytostatic

O’Brien et al. Tumor Biology 2001

CA 125 TO ACCELERATE PHASE II CLINICAL TRIALS

• Surrogate Marker for Response in Phase II Trials

- A 50% and 75% Decrease in CA125 has correlated with Response Rates in 19 Phase II Trials of 14 Different Cytotoxic Drugs with >1000 Patients (Rustin, et al)

- Use of CA125 could Double Accrual

- Discontinue Trials with Poor Response

- Expand Accrual to achieve RECIST Criteria

Selection of Active Drugs in Phase II Trials for Ovarian Cancer According to

CA 125 Response Rates

Paclitaxel Platinum based

Docetaxel Rhizoxin

Etoposide Tallimustine

Fosquidone Tomudex

Gemcitabine Topotecan

Isotretinoin/Calcitriol Oxaliplatin

Altretamine

CA 125 TO ACCELERATE PHASE III CLINICAL TRIALS

• CA 125 as an Endpoint for Time to Progression in Phase III Trials - Rise >2-fold above Normal or above Nadir- 84-94% Sensitive and >98% Specific- 80% precede or coincide with RECIST

• Combine with RECIST Criteria- RECIST takes Precedence- CA125 must be at the Same Time Points in

Both Arms- Shorten Duration of Trials

Comparison of CA-125 and Standard Definitions of Progression in the Intergroup Trial of Cisplatin and Paclitaxel Versus Cisplatin and Cyclophosphamide

(Rustin et al 2006)

Standard

Definitions

CA 125

Definitions

Combined

CA 125 TO EVALUATE NOVEL CYTOSTATIC DRUGS

• Monitor Response to New Cytostatic Drugs

- Many Targeted Therapies are Cytostatic and Stabilize Disease

- Effective Drugs could arrest A Rising CA 125 in Recurrent Disease

- Measure the Decreased Slope or Use Doubling of CA125 as Progression

RANDOMIZED

Regimen IThalidomide200 mg PO daily qhs with weekly doseEscalation to a maximum dose of 400 mg daily*

Regimen IITamoxifen20 mg PO BID to a maximum dose of 40 mg

Until disease progression or adverse effects

prohibit further

therapy for one year

A RANDOMIZED STUDY OF TAMOXIFEN VERSUS THALIDOMIDE (NSC#66847) IN PATIENTS WITH BIOCHEMICAL RECURRENCE ONLY OF EPITHELIAL OVARIAN

CANCER, CANCER OF THE FALLOPIAN TUBE, AND PRIMARY PERITONEAL CARCINOMA AFTER FIRST LINE CHEMOTHERAPY

-Epithelial ovarian, fallopian tube or peritoneal carcinoma-Complete clinical regression following front-line chemotherapy-Biochemical recurrence based on rising CA125

FRONTIERS IN TUMOR MARKERS:

PREDICTION OF REPONSE TO THERAPY

BIOMARKERS TO PREDICT RESPONSE TO INDIVIDUAL DRUGS IN OVARIAN CANCER

• Platinum Compounds- 70% Response Rate- Very High Negative Predictive Value (>95%) Required to Forego Treatment

• Taxanes- 50% Response Rate- Additive Not Synergistic- 50% Don’t Benefit

• Difficult to Study These Drugs as Individual Agents

• Multiple Drugs are Also Active for Salvage

BIOMARKERS TO PREDICT RESPONSE TO INDIVIDUAL DRUGS IN OVARIAN CANCER

• Clonogenic Assays

• Biomarkers for Platinum Resistance- p53- ERCC1- Lack of Transporters- XIAP

• Biomarkers for Taxane Resistance- MDR1- Tubulin Mutations- HER-2- Survivin

BIOMARKERS TO PREDICT RESPONSE TO INDIVIDUAL DRUGS IN OVARIAN CANCER

• Future Directions

- Expression Array Analysis

- Changes in Proteomic Profiles

- Circulating Tumor Cells

- New Therapies with Specific Targets

- Molecular Imaging

REVERSE PHASE PROTEIN LYSATE ARRAYS TO IDENTIFY ACTIVATED SIGNALING PATHWAYS

FRONTIERS IN TUMOR MARKERS:

EARLY DETECTION OF OVARIAN CANCER

RATIONALE FOR OVARIAN CANCER SCREENING

• Ovarian Cancer Limited to the Ovaries (Stage I) can be Cured in 90% of Patients with Currently Available Therapy

• Disease that has Spread from the Pelvis (Stage III-IV) can be Cured in only 20% or Less

• Only 25% of Ovarian Cancers are Currently Diagnosed in Stage I

• Detection of Preclinical Disease at an Earlier Stage Might Improve Survival

MINIMAL REQUIREMENTS FOR OVARIAN CANCER SCREENING

• Postmenopausal Prevalence: 40/100,000

• High Sensitivity: 75%

• Very High Specificity: 99.6%

• Positive Predictive Value: 10%

APPROACHES TO SCREENING FOR EPITHELIAL OVARIAN CANCER

• Ultrasonography

• Serum/Plasma/Urine Markers

• Two Stage Strategies

CA 125 FOR EARLY DETECTION OF OVARIAN CANCER

• Elevated 10-60 Months Prior to Diagnosis

• Detects 50 - 60% of Stage I Disease

• Specificity of a Single Determination is 99%, but This is Still Inadequate

• Combination with Ultrasonography can increase Specificity

CA 125 FOR EARLY DETECTION OF OVARIAN CANCER

• In the PLCO Trial, CA125 alone had a PPV of 3.7%, TVS had a PPV of 1%, both together had a PPV of 23.5%, but 60% of Invasive Cancers would not be Detected

• Specificity can be Improved by Combining CA 125 with Ultrasound Sequentially

• Specificity and Sensitivity can be Improved by Sequential Monitoring Over Time

Analysis of Changes in CA 125 Over time

• Rising CA 125 Values are Associated with Ovarian Cancer

• Stable CA 125 Values, Even when Elevated, are Associated with Benign Conditions

• A Computer Algorithm has been Developed that Estimates Risk of Ovarian Cancer based on Change Point Analysis During Sequential Monitoring Over Time

Analysis of Changes in CA 125 Over Time: 6,532 Women >50 Years Screened Producing a Specificity

of 99.8% and a Positive Predictive Value of 19% (Menon, JCO, 2005)

RANDOMIZED TRIAL OF SCREENING WITH THE CA125 ALGORITHM AND ULTRASOUND OR WITH ULTRASOUND ALONE (UKCTOCS)

• Two Hundred Thousand Postmenopausal Women will be Randomized to Three Groups– Control (100,000)– Annual TVS (50,000)– CA125 Algorithm Prompting TVS (50,000)

• Women will be Screened and Followed for 7 Years

INCREASING THE SENSITIVITY OF TWO STAGE SCREENING STRATEGIES FOR

OVARIAN CANCER

• CA125 Levels are >35 U/ml in 50-60% of Patients with Stage I Ovarian Cancer

• Using an Algorithm that Detects Disease when CA125 <35 U/ml, Sensitivity Could Exceed 60%

• In 20% of Ovarian Cancers CA125 Cannot Be Detected in Tissue Sections

• Greater Sensitivity Might be Achieved with Multiple Markers, Provided that Specificity is not Compromised

OTHER ANTIGENIC MARKERS FOR EPITHELIAL OVARIAN CANCER

• CEA

• CA 19-9

• CA 15-3

• TAG 72

• HMFG-2

• Galactosyltransferase

• Placental alkaline phosphatase

• Tissue peptide antigen

• NB/70K

• erbB-2 (HER-2-neu)• CASA• LASA• CYFRA 21-1• TAT1• IL-2 receptor• Cathepsin 1• Urinary gonadotropin

peptide• Matrix metalloproteinases• OVX1• M-CSF

APPROACHES TO IDENTIFYING NOVEL MARKERS FOR EPITHELIAL OVARIAN CANCER

• Murine Monoclonal Antibodies– Mesothelin

• Lipid Analysis - LPA

• Expression Array Analysis– HE4– Kallikreins– Prostasin– Osteopontin– VEGF– IL-8

• Proteomics

A COMBINATION OF SERUM SOLUBLE MESOTHELIN RELATED PROTEIN (SMRP) AND CA125 IS SUPERIOR TO

EITHER ALONE FOR DISTINGUISHING OVARIAN CANCER CASES FROM HEALTHY CONTROLS

Soluble Mesothelin Related Protein (SMRP)

• Serum SMRP complements CA 125 in detecting Ovarian Cancer

• When corrected for GFR, Urine SMRP detects 39% of Stage I Ovarian Cancers

• Bcl-2 is also elevated in Urine from >80% of ovarian cancer patients (Kruk et al 2005)

HE4 IS A BIOMARKER BOTH FOR OVARIAN AND ENDOMETRIAL CANCER

• HE4 is as Sensitive as CA 125 for detecting Ovarian Cancer, but has better Specificity for distinguishing Malignant and Benign Pelvic Masses

• HE4 is Twice as Sensitive as CA 125 for Endometrial Cancer detecting 36% of All Stages and 17% of Stage I Cancers

PROTEOMIC ANALYSIS OF OVARIAN CANCER

2000 2250 2500 2750

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Normal

Ovarian Cancer

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2000 2250 2500 2750

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2000 2250 2500 2750

Normal

Ovarian Cancer

Application of Proteomics to Early Detection of Ovarian Cancer

• Identify a Distinctive Pattern of Peptide Expression in Serum or Urine

• Identify Specific Peptides and Develop Individual Assays that can be analyzed in Combination

USE OF PROTEOMIC PATTERNS TO IDENTIFY OVARIAN CANCER

• SELDI and MALDI-TOF have been used to analyze the Pattern of Peptides in Sera from Healthy Women and Ovarian Cancer Patients (Petricoin, et al)

• Very High Sensitivity and Specificity have been reported (Fishman, et al)

• Over the last 4 Years, the Computer Algorithm has Evolved

•In Published Studies, Relatively Few Early Stage Patients have been Reported

•Others have had difficulty in confirming the Analysis and have identified Problems with the Methods Used

STUDY DESIGN AND PATIENT FLOW FOR SAMPLES FROM FIVE ACADEMIC MEDICAL CENTERS

Identification of Biomarkers from the Proteomic Profile

• Seven Biomarkers have been Identified that Distinguish Benign from Malignant Pelvic Masses(Zhang, et al)

• Of these, Downregulation of Three Biomarkers Consistently Distinguishes Ovarian Cancer Patients from Healthy Individuals

- Apolipoprotein A1

- Truncated Transthyretin

- CTAPIII

LuminexLuminex Assay Assay

Multiplex Assay of Multiple Antigens and Antibodies (Gorelik, 2005)

• Lokshin and Colleagues at Pittsburgh Cancer Center have adapted Multiple Assays to a Luminex LabMAP Format

• In Published Studies, CA125, G-CSF, IL-6, EGF and VEGF produced 86% Sensitivity and 93% Specificity for Early Stage Disease

• Recently, they have analyzed some 40 biomarkers with increased Sensitivity and Specificity

FRONTIERS IN TUMOR MARKERS • CA 125 could facilitate and accelerate Drug Evaluation by

serving as a Surrogate Endpoint for Response in Phase II Clinical Trials and for Recurrence in Phase III Trials in Ovarian Cancer

• New Technologies are providing Multiple Candidates for Predictive Markers of Response to Taxanes and Platinum Compounds

• Changes in a Panel of Serum Markers may provide a First Step of a Two Phase Strategy for Early Detection of Ovarian Cancer

• HE4 may provide an Effective Marker for Endometrial Cancer