Current and Future Perspectives on Irinotecan Pharmacogenomics ACPS Clinical Pharmacology Subcommittee 3 November 2004 Luis A. Parodi, PhD - Director and Site Head, Clinical Pharmacogenomics Mark E. Morrison, MD, PhD - Medical Director, Team Leader, Camptosar Akintunde Bello, PhD – Associate Director, Clinical Sciences

Presentation Overview Commitment to safety Application of pharmacogenomics at Pfizer Review & analysis of published data Ongoing studies Collaboration with FDA

Pharmacogenomics at Pfizer Discovery Development DISEASE TARGET SELECTING PHARMACO- GENOMICS GENETICS VARIABILITY RESPONDERS Improving Early Decision Making Predicting Efficacy and Safety Choosing the Best Targets Better Understanding of Our Targets .

Chronology of Pharmacogenomics Activities Related to Irinotecan Ca. 1996-7 - Provided irinotecan clinical supplies to NCI in support of early irinotecan pharmacogenomics (PGx) research at University of Chicago 2000 to present - Supported and sponsored several irinotecan clinical trials with PGx 2001 to present - Provided grant support to NCCTG for PGx in N9741 Ph-3 mCRC trial 2002 - Collaboration with Epidauros AG in PGx of drug transporters and metabolizing enzymes 2004 - Initiating irinotecan neoadjuvant study with PGx component

Irinotecan Disposition & Metabolism NPC & APC Inactive Metabolites CYP3A4/5 Carboxylesterases (CE1 & CE2) Other UGT Isoforms? UGT1A1 Irinotecan SN-38 SN-38G Parent Drug Active Metabolite Inactive Metabolite GI Absorption BCRP Biliary Excretion MDR1 (PGP)? MRP2? C-MOAT? SN-38 SN-38G Glucuronidase (Bacterial) GI Lumen

Key Publications Correlating UGT1A1 7/7 Genotype and Safety Author*, Year N Tumor Type Irinotecan Dose (mg/m2), Schedule, & Combo Innocenti, 2004 66 Lung 29%, GE 21%, CRC 15%, other 35% 350 q-3-wk, single agent Rouits, 2004 75 CRC 100% 85 wkly + FU/LV 180 biwkly + FU/LV Marcuello, 2004 95 350 q-3-wk, single agent 350 q-3-wk + raltitrexed 80 wkly + FU Ando, 2000 118 SCLC 18%, NSCLC 55%, CRC 18%, other 9% Various Font, 2003 51 NSCLC 100% 70 wkly + docetaxel *Full citations given in Background Document.

Severe Neutropenia Risk: 7/7 vs 6/6 + 6/7 Genotypes Unadjusted Odds Ratio Author n/N (%) Est. Odds Ratio 95% CI 7/7 6/6 + 6/7 Innocenti 3/6 (50%) 3/53 (6%) 16.7 2.3 - 120.6 Rouits 4/7 (57%) 10/66 (15%) 7.5 1.4 - 38.5 Marcuelloa 4/10 (40%) 18/85 (21%) 2.5 0.6 - 9.7 Andob 22/111 (20%) 5.4 1.1 - 25.9 aGr 3+ neutropenia. bGr 4 leukopenia and/or Gr 3+ diarrhea.

Severe Neutropenia Risk: 7/7 vs 6/6 + 6/7 Genotypes Summary No adjustments for known risk factors There seems to be a statistically significant association in 3 of 4 studies between 7/7 and severe neutropenia Potential causes for interstudy variation include: Small sample sizes Different schedules/dose intensity Other known risk factors (bilirubin, age, performance status, pelvic radiation) Difference in population and cancer types treated

Severe (Gr 3+) Diarrhea Risk: 7/7 vs 6/6 + 6/7 Genotypes Unadjusted Odds Ratio n/N (%) Est. Odds Ratio 95% CI 7/7 6/6 + 6/7 Innocenti 1/6 (17%) 2/53 (4%) 5.1 0.4 - 66.6 Rouits 2/7 (29%) 11/66 (17%) 8.4 0.3 - 11.7 Marcuelloa 7/10 (70%) 22/85 (26%) 6.7 1.6 - 28.1 Andob 4/7 (57%) 22/111 (20%) 5.4 1.1 - 25.9 Font 1/7 (14%) 11/40 (27%) 0.4 0.05 - 4.1 aGr 3+ diarrhea; bGr 4 leukopenia and/or Gr 3+ diarrhea. Association between 7/7 and severe diarrhea 2 of 5 studies show statistical significance

Summary of published data Comprehensive review of published literature Evaluate the frequencies of severe neutropenia & diarrhea and genotypes Conclusion: Significant association of the UGT1A1 7/7 genotype and the risk of developing Grade 4 neutropenia The association with severe diarrhea not as consistent between studies Translation of association data to a predictive performance requires assessing multiple parameters Sensitivity, specificity, and positive & negative predictive values.

Severe Neutropenia: Translating Associations into a Predictive Test Assumption: Genotyping assay is 100% accurate for detection of UGT1A1*28 allele Clinical Sensitivity Clinical Specificity PPV* NPV* Innocenti 0.5 0.94 Rouits 0.29 0.95 0.57 0.85 Marcuello 0.18 0.92 0.4 0.79 Ando 0.15 0.97 0.8 Overall 0.22 0.83 * PPV, positive predictive value; NPV, negative predictive value. Balancing neutropenia and efficacy in 7/7 positive patients: Neutropenia is generally manageable Dose reduction may be unnecessary for 50%, with unknown consequences

Ongoing Activities Ongoing Pfizer sponsored and supported trials aim to: Better quantify the association between the UGT1A1*28 variant (as well as other genetic factors) and severe neutropenia & diarrhea Discussions are in progress with FDA on revising the Camptosar label to include pharmacogenomics information

Pfizer-Supported and -Sponsored Trials with a Pharmacogenomic Component* (Nov 2004) Protocol Study Pop’n Regimens n***/N NCCTG N9741 1st-line CRC IFL, FOLFOX, IROX 520/795 SWOG 0124 Extensive SCLC cis + irino, cis + etop n/620 NCCTG N0147 Stage 3 Adj CRC FOLFOX  cetux, FOLFIRI  cetux, FOLFOX FOLFIRI  cetux n/4800 PFE BICC-C†** FOLFIRI + bev  celecox, IFL + bev  celecox, (irino + cape  celecox) >250/1200 PETACC-3† Stg 2-3 Adj CRC FU/LV, FU/LV/irino >700/3278 * Multiple genes tested. ** BICC-C amended to add bev and close irino + cape + celecox arm. *** Number of patients on whom genomic analyses were/will be performed. † Pfizer-sponsored trial.

What do we hope to learn from these studies? Better define magnitude and strength of the association between UGT1A1*28 and safety Identify other potential covariates of severe neutropenia & diarrhea Provide information & guidance to health care practitioners to aid in their treatment decisions