EGFR Inhibitors in Colorectal Cancer John L. Marshall, MD Lombardi Comprehensive Cancer Center

EGF TGF  Ligand Binding Phosphorylation and Activation Dimerization HeterodimerHomodimer ATP High affinity binding Ligand Binding and Dimerization Results in TK Activation Source: With permission from Amgen Inc.

P13K FKHR Akt mTOR PTEN MEK 1/2 MAPK BAD GSK-3 SOS Grb-2 Shc Grb-2 SOS Ras Raf Jun FOS Myc p27 Cyclin D-1 Ligand Signal Adapters and Enzymes Signal Cascade EGFr dimer MAPK = mitogen-activated protein kinase P13k = phosphatidylinositol 3-kinase Transcription Factors EGFR Activation and Signaling Pathways Source: With permission from Amgen Inc.

Proliferation Angiogenesis Cell Survival Metastatic Spread EGFr Activation Tumor Blood Vessel Blood Vessel Spread of cancer cells EGFR Activation Mediates Several Processes Source: With permission from Amgen Inc.

NSCLC40-80 SCCHN95 Colorectal25-77 Glioblastoma40-60 Breast14-91 Prostate Ovarian35-70 Esophageal35-88 Pancreatic30-50 SCCHN = squamous cell carcinoma head and neck. Arteaga C. Semin Oncol. 2003;30(suppl 7):3-14. EGFR Expression (%)Tumor Type EGFR Expression Correlates With Poor Prognosis in Selected Solid Tumors *Responses observed in various solid tumors for gefitinib, erlotinib, and cetuximab.

Anti-EGFr Monoclonal Antibodies Mendelsohn J. J Clin Oncol. 2002;20(suppl 18):1s-13s. Tewes M, et al. Proc Am Soc Clin Oncol Abstract 378. Sridhar SS, et al. Lancet Oncol. 2003;4: Vanhoefer U, et al. J Clin Onc 2004;22(1): Monoclonal AntibodyDescriptionStatus Cetuximab (C-225) Chimeric IgG 1 Approved: Colorectal cancer Submitted: Head and Neck (H&N) cancer Phase 2: NSCLC, Others Matuzumab (EMD 72000) Humanized IgG 1 Phase 2 Trials: Recurrent ovarian cancer, NSCLC Phase I-2 Trials: Colorectal cancer Panitumumab (ABX-EGF) Fully human IgG 2 Phase 2-3 Trials: Colorectal cancer, NSCLC, Others

Properties of Cetuximab  IgG1 MAb (chimerized)  Binds specifically to EGFR and its heterodimers  Binds to EGFR with high affinity (K d = 2.0 x 10 –10 M): 1 log higher than the natural ligand  Following the recommended dose regimen (400 mg/m 2 initial dose/250 mg/m 2 weekly dose), the mean half-life was 114 hours (range hours)  Competitively inhibits ligand binding to EGFR  Stimulates receptor internalization  Blocks receptor dimerization, tyrosine kinase phosphorylation, and signal transduction Shitara K, et al. Cancer Immunol Immunother. 1993;36: LoBuglio AF, et al. Proc Natl Acad Sci U S A. 1989;86: ERBITUX Package Insert, June Data on file. ImClone Systems Incorporated and Bristol-Myers Squibb Company; 2004.

Patients with EGFR-expressing metastatic CRC progressed after receiving irinotecan-based chemotherapy RANDOMIZATION CETUXIMAB with irinotecan n = 218 Cetuximab Randomized Pivotal Trial in Metastatic Colorectal Cancer Randomized Phase II Study Design ERBITUX Package Insert, June CETUXIMAB as a single agent n = 111

Cetuximab Randomized Pivotal Trial in Metastatic Colorectal Cancer Characteristic All Patients (n = 329) Gender, % Male Female Age, y Median Range Karnofsky Performance Status, % < 80  Prior oxaliplatin treatment, %63 Patient Baseline Demographics ERBITUX Package Insert, June 2004.

Cetuximab/C225 in Colon Cancer CPT-11 + C225 C225 alone 2:1 RRTTPOS pts crossover Source: Cunningham D et al. N Engl J Med 2004;351:

The “Bond” Trials C225 Alone C225 + Bev PValue C225 + CPT-11 C225 + CPT-11 + Bev P Value PR11%23%0.0523%38%0.03 TTP 1.5 mo 5.6 mo > mo 7.9 mo >0.01 OS 6.9 mo NR- 8.6 mo NR- Sources: Cunningham D et al. N Engl J Med 2004;351: Saltz L et al. Presentation. ASCO GI Symposium Abstract 169b

Cetuximab in the first line? FOLFIRI + Cetuximab –59% PR (13/22) 36% SD (8/23) Raoul et al ECCO 2003 FOLFOX + Cetuximab –81% PR ASCO 2004 –82% CR/PR, 12.5 median PFS ASCO 2005 Sources: Raoul et al. Proc ECCO 2003;Abstract 289. Tabernero JM et al. Proc ASCO 2004;Abstract Rubio ED et al. Proc ASCO Abstract 3535

Monoclonal Antibodies as Targeted Therapy: Evolution to Fully Human Antibody 100% Mouse Protein34% Mouse Protein10% Mouse Protein100% Human Protein Mouse Fully Human Humanized Chimeric cetuximab matuzumabpanitumumab mouse human

Panitumumab Phase 2 Study: Monotherapy for CRC - Methods Eligibility requirements: –Metastatic colorectal carcinoma, ECOG 0-1 –Measurable disease –Failed prior therapy with a fluoropyrimidine +/- leucovorin, and either irinotecan, oxaliplatin or both –EGFr overexpression by immunohistochemistry Cohort A: 2+ or 3+ in > 10% of tumor cells Cohort B: 2+ or 3+ in 10% of tumor cells Hecht JR, et al. Proc Am Soc Clin Onc. 2004,abstract poster

Panitumumab Phase 2 Study: Monotherapy for CRC - Methods Dose: 2.5 mg/kg –Infused over 1 hour –No loading dose –Administered without premedication –Given weekly until disease progression or unacceptable toxicity Assessments: –Toxicity assessed weekly –Tumor assessment every 8 weeks Hecht JR, et al. Proc Am Soc Clin Onc. 2004,abstract poster

Panitumumab Phase 2 Study: Monotherapy for CRC – Toxicity (Treatment-related Adverse Events) Selected Treatment-emergent adverse events reported through cycle 2 as possibly, probably, or definitely related to panitumumab Events starting before cycle 1 or after the first infusion in cycle 3 are excluded. Hecht JR, et al. Proc Am Soc Clin Onc. 2004,abstract 3511, poster. Data on file. ToxicityAll GradeGrade 3Grade 4 Rash140 (95%)5 (3%)0 Fatigue34 (23%)3 (2%)0 Diarrhea30 (20%)1 (1%)0 Vomiting10 (7%)2 (1%)0

Panitumumab + Chemotherapy 1 st Line mCRC Phase 2 Study: Methods Multicenter, open-label, single-arm study consisting of 2 parts: – Part 1: Patients (N=19) received 1 st line panitumumab/IFL therapy: Panitumumab 2.5 mg/kg/week administered intravenously over 1 hour in 6-week courses (days 1, 8, 15, 22, 29 and 36), immediately followed by: IFL regimen: irinotecan (IR) 125 mg/m 2, leucovorin (LV) 20 mg/m 2, 5-fluorouracil (5FU) 500 mg/m 2 on days 1, 8, 15 and 22 Enrollment for Part 1 is closed – Part 2: Patients received 1 st line panitumumab/FOLFIRI therapy Part 2 is ongoing with enrollment closed (N=24); patients are continuing therapy Berlin J, et al. ESMO a265

Panitumumab + Chemotherapy 1 st Line mCRC Phase 2 Study, Part 1: Skin Toxicity Skin ToxicAll Patients (N=19) Worst Severity Mild Moderate Severe Life-Threatening 9 (47%) 7 (37%) 3 (16%) 0 ( 0%) Median (95% CI) Time to Onset, days 11.0 (7.0, 15.0) Berlin J, et al. ESMO a265

Panitumumab + Chemotherapy 1 st Line mCRC Phase 2 Study, Part 1: Efficacy All Patients (N=19) Overall Response9 (47%) Partial Response Complete Response 8 (42%) 1 ( 5%) Stable Disease6 (32%) Progressive Disease1 ( 5%) No Assessment3 (16%) Treated pts received at least 1 dose of panitumumab or 1 dose of IFL Berlin J, et al. ESMO a265

PanitumumabPD Follow-up 6.0 mg/kg Q2W + BSC BSCPD Follow-up RANDOMIZE Optional Panitumumab Crossover Study Randomization stratification ECOG score:0-1 vs. 2 ECOG score:0-1 vs. 2 Geographic region:Western EU vs. Central & Eastern EU vs. Rest of World Geographic region:Western EU vs. Central & Eastern EU vs. Rest of World Randomized Controlled Phase 3 Trial in mCRC 1:1 Source: Peeters M et al. Presentation. AACR Abstract CP-1

Study Endpoints Primary Progression-free survival (per blinded central radiology assessment of modified-RECIST criteria) Secondary Overall survival time and best overall objective response (central radiology) - co-secondary Duration of and time to response Safety Incidence of adverse events (including all, grade 3/4, treatment related events), antibody formation Source: Peeters M et al. Presentation. AACR Abstract CP-1

Metastatic colorectal adenocarcinoma (mCRC) ECOG score 0 to 2 Radiologic documentation of disease progression after fluoropyrimidine, irinotecan, and oxaliplatin – During or within 6 months following most recent chemotherapy regimen – Failure after prespecified doses of irinotecan and oxaliplatin EGFr membrane staining on ≥ 1% tumor cells (IHC, central laboratory) Adequate hematologic, renal, and hepatic function Key Eligibility Criteria Source: Peeters M et al. Presentation. AACR Abstract CP-1

Demographics and Disease Characteristics Panitumumab Plus BSC (N=231) BSC Alone (N=232) Sex – n (%) Men Women 146 (63) 85 (37) 148 (64) 84 (36) Median (range) age – years62 (27, 82)63 (27, 83) ECOG status – n (%) 0-1 ≥ (87) 30 (13) 195 (84) 37 (15) Number of metastatic sites – n (%) (70) 70 (30) 161 (70) 69 (30) Prior adjuvant chemotherapy – n (%)86 (37)78 (34) Prior chemotherapy – n (%) At least 2 lines At least 3 lines 230 (100) 84 (36) 232 (100) 88 (38) Mean (SD) % of tumor cells with EGFr membrane staining32.5 (29.3)27.5 (26.1) Intensity of EGFr staining – n (%) 3+ (strong) 2+ (moderate) 1+ (weak) 0 (none) 47 (20) 122 (53) 60 (26) 2 (1) 41 (18) 113 (49) 78 (34) 0 (0) Source: With permission. Peeters M et al. Presentation. AACR Abstract CP-1

Event-free Probability Weeks from Randomization Hazard ratio=0.54 (95% CI: 0.44, 0.66) Stratified log-rank test p < Progression-Free Survival Panitumumab BSC Patients at risk: Panitumumab BSC Primary Analysis, All Randomized Analysis Set, Central Radiology Source: With permission. Peeters M et al. Presentation. AACR Abstract CP-1

0% 10% 20% 30% 40% 50% 60% Kaplan- Meier Progression-Free Survival Rates at Prespecified Time Points 49% 30% 35% 14% 26% 9% 5% 18% 4% 1%1%1% 4% 10% Panitumumab (N=231) BSC (N=232) Wk 8 Wk 12 Wk 16 Wk 24 Wk 32 Wk 40 Wk 48 Primary Analysis, All Randomized Analysis Set, Central Radiology % Progression Free (95 % CI) Patients at risk: Panitumumab BSC Source: With permission. Peeters M et al. Presentation. AACR Abstract CP-1

% Surviving Months from Randomization Panitumumab (N=231) BSC (N=232) Hazard ratio=0.93 (95% CI 0.73, 1.19) Stratified log-rank p = Patients at risk: Panitumumab BSC Overall Survival – Interim Analysis (All Randomized Analysis Set) Note: There were 250 events Source: With permission. Peeters M et al. Presentation. AACR Abstract CP-1

Note: BSC patients censored at the time that they received their first dose of panitumumab; Included confirmed and unconfirmed responses by investigator (RECIST criteria) HR= 0.78 (95% CI: 0.61, 1.01) PanitumumabBSC Patients at risk: Panitumumab BSC Survival Probability Months from Randomization Overall Survival: Censored BSC Patients Who Subsequently Responded After Crossing Over Source: With permission. Peeters M et al. Presentation. AACR Abstract CP-1

Safety – Grade 3/4 Adverse Events Panitumumab (N = 229) BSC (N = 234) Grade 3Grade 4Grade 3Grade 4 Patients with any grade 3 or 4 event 75 (33)4 (2)41 (18)4 (2) Abdominal pain17 (7)0 (0)8 (3)3 (1) Fatigue10 (4)0 (0)7 (3)0 (0) Dyspnea9 (4)2 (1)8 (3)0 (0) Anorexia7 (3)0 (0)5 (2)0 (0) Jaundice7 (3)1 (0)3 (1)1 (0) Asthenia6 (3)1 (0)5 (2)0 (0) Vomiting5 (2)0 (0)2 (1)0 (0) Ascites3 (1)1 (0)2 (1)0 (0) Diarrhea3 (1)0 (0) Intestinal obstruction3 (1)4 (2)2 (1)0 (0) Paronychia3 (1)0 (0) Deep vein thrombosis2 (1)1 (0)0 (0) Pulmonary embolism0 (0)1 (0)0 (0) MedDRA version 8.0 preferred terms; graded per NCI CTCAE version 2.0 Source: Peeters M et al. Presentation. AACR Abstract CP-1

Grade 2-4 Grade 1 Survival Probability Months from Randomization Patients at risk: Grade 2-4 Grade Overall Survival by Worst Grade of Skin Toxicity in the Panitumumab Patients a Hazard ratio for Grade 2-4 relative to Grade 1, stratified by ECOG and geographic region Hazard ratio = 0.61 a (95% CI: 0.40, 0.95) p = Source: With permission. Peeters M et al. Presentation. AACR Abstract CP-1

Conclusions and Questions EGFR antibodies are active in colon cancer Skin rash toxicity is the biggest barrier to more widespread use Approval(s) in “last line” therapy –Role in 1 st line or adjuvant to be determined