Genetic polymorphisms, toxicity, & response rate in African Americans (AA) with metastatic colorectal cancer compared to Caucasians (C) treated with IFL, FOLFOX or IROX in Intergroup N9741 R. M. Goldberg, H. L. McLeod, D. J. Sargent, R. F. Morton, E. M. Green, C. Fuchs, R. K. Ramanathan, S. K. Williamson, B. P. Findlay, H. C. Pitot, S. R. Alberts

Relative Survival for Colorectal Carcinoma by Race/Ethnicity, SEER Years after Diagnosis Survival (%) White, non-Hispanic Black/African American Asian/Pacific Islander Hispanic

Potential Explanations: Societal Socioeconomic Issues Socioeconomic Issues Hypothesis: AA have less access to medical care Hypothesis: AA have less access to medical care Corollary: AA are diagnosed at later stage Corollary: AA are diagnosed at later stage Hypothesis: AA often are of lower socioeconomic status Hypothesis: AA often are of lower socioeconomic status Corollary: AA have poorer access to ideal care Corollary: AA have poorer access to ideal care

Potential Explanations: Biological Tumor Biology Tumor Biology Hypothesis: AA have more aggressive disease Hypothesis: AA have more aggressive disease Corollary: AA have a worse outcome regardless of access Corollary: AA have a worse outcome regardless of access Host Biology Host Biology Hypothesis: AA respond differently to chemotherapy Hypothesis: AA respond differently to chemotherapy Corollary: AA should have different treatment algorithms and may benefit from the use of different drugs or different drug doses Corollary: AA should have different treatment algorithms and may benefit from the use of different drugs or different drug doses

Specific Aims Compare AA to C patients enrolled in N9741 Compare AA to C patients enrolled in N9741 RR, TTP, and OS RR, TTP, and OS Chemotherapy toxicities Chemotherapy toxicities Prevalence of polymorphisms in key genes coding for enzymes involved in drug metabolism Prevalence of polymorphisms in key genes coding for enzymes involved in drug metabolism Correlate clinical endpoints & polymorphisms Correlate clinical endpoints & polymorphisms

1412 stage IV patients 486 with pharmacogenetic data 1412 stage IV patients 486 with pharmacogenetic data IFL: Irinotecan + 5-FU/LVIFL: 5-FU/LV IROX: Irinotecan + oxaliplatin FOLFOX: Oxaliplatin + 5-FU/LV RANDOMIRANDOMIZATZATIONIONRANDOMIRANDOMIZATZATIONION N9741: Schema

Number of Patients by Race: Self Reported AACCTotal All 117 (8%) IFL 40 (10%) FOLFOX4 50 (8%) IROX 27 (7%)

Response Rate: Overall and By Arm AACP-Value All31%41%0.015 IFL28%34%0.44 FOLFOX434%49%0.047 IROX26%38%0.22

Median TTP: Overall and By Arm AACP-Value* All 7.3 mo 8.2 mo 0.56 IFL 5.5 mo 6.9 mo 0.13 FOLFOX mo 9.3 mo 0.98 IROX 6.7 mo 7.3 mo 0.62 *Log-rank test p-value

Median OS: Overall and By Arm AACP-Value* All 16.3 mo 17.9 mo 0.44 IFL 12 mo 15.2 mo FOLFOX mo 19.6 mo 0.47 IROX 22 mo 16.7 mo *Log-rank test p-value

Median OS: 95% Confidence Intervals AACP-Value All 16.3 mo mo IFL 12 mo mo FOLFOX mo mo IROX 22 mo mo

Toxicity : All Arms Combined AA n=42 C n=472 P-value Any grade > 3 34%48%0.004 G4 Neutropenia 9%8%0.93 G4 Diarrhea 5%17%<0.001 Paresthesias9%8%0.73 Vomiting6%4%0.43

IFL Toxicity AA n=42 C n=472 P-value Any grade > 3 28%45%0.035 G4 Neutropenia 10%5%0.24 G4 Diarrhea 8%23%0.024 Paresthesias3%2%0.68 Vomiting3%11%0.87

FOLFOX Toxicity AA n=50 C n=590 P-value Any grade > 3 36%46%0.16 G4 Neutropenia 8%12%0.38 G4 Diarrhea 2%10%0.06 Paresthesias1614%0.71 Vomiting4%2%0.42

IROX Toxicity AA n=27 C n=335 P-value Any grade > 3 41%55%0.16 G4 Neutropenia 7%5%0.55 G4 Diarrhea 7%22%0.07 Paresthesias7%6%0.82 Vomiting15%10%0.41

Irinotecan Pathway CPT-11 cell membrane CPT-11 SN-38 TOP1 Cell Death APC SN-38G ABCB1 CYP3A4 CYP3A5 CES1 CES2 UGT1A1 CES1 CES2 ABCC2 ABCG2 ABCC1 ADPRT TDP1 CDC45L XRCC1 NFKB1 NPC ABCB1

Controls Irinotecan and SN- 38 Efflux from Cells AAC p value abcb1_3435< C/C C/C51%18% Other Other49%82% abcg20.02 G/T or T/T G/T or T/T3%22% G/G G/G97%78% abcc2_30.05 A/A A/A5%22% Other Other95%78%

CYP3A: Prevents Activation to SN-38 AACP-value CYP3A4 < A/A G/G T/C A/A G/G T/C89%7% A/A & T/T A/A & T/T11%93% CYP3A5< C/C & T/T C/C & T/T86%11% C/C C/C14%89%

Polymorphisms in UGT1A1 do not predict diarrhea or overall toxicity AACP-value UGT1A /6 6/617%47% 6/7 6/763%44% 7/7 7/721%9% UGT1a T/T T/T12%8% Other Other88%92%

Oxaliplatin Detoxify GSTP1 GSTM1 SOD1 MPO NQO1 POLH POLB Translesional replication Damage recognition HMG1 Excision repair Cell Death ERCC2 ERCC1 XRCC1 cell membrane Oxaliplatin ATP7A SLC31A1 ABCG2 ABCC2 Oxaliplatin Oxaliplatin Pathway

ERCC Genes Repair Oxaliplatin Adducts AACP-value Ercc1_n A/A A/A5%22% Other Other95%78% Ercc2_d A/A A/A4%22% A/B A/B29%50% B/B B/B70%28%

GST Genes Detoxify Oxaliplatin AACP-value Gstp1_I T/T T/T26%44% C/T C/T53%45% C/C C/C21%11% GSTM1_ Absent Absent3%51% Present Present97%49%

Conclusions: Among the Patients in This Trial AA have a significantly lower RR AA have a significantly lower RR No differences in TTP were observed No differences in TTP were observed Differences in OS were inconsistent between AA and C Differences in OS were inconsistent between AA and C AA have significantly less severe toxicity, mainly less severe diarrhea AA have significantly less severe toxicity, mainly less severe diarrhea AA and C have significantly different frequencies of polymorphisms in candidate genes coding for key enzymes involved in drug activation, metabolism, and disposition AA and C have significantly different frequencies of polymorphisms in candidate genes coding for key enzymes involved in drug activation, metabolism, and disposition

Implications FOLFOX remains the preferred regimen in AA & C FOLFOX remains the preferred regimen in AA & C Dose escalation may be possible in some AAs Dose escalation may be possible in some AAs Caution: Correlation of polymorphisms with response and toxicity may not be causal Caution: Correlation of polymorphisms with response and toxicity may not be causal More research in bigger populations is indicated More research in bigger populations is indicated FOCUS (2135 pts) and CALGB/SWOG (2380 pts) have/are collecting germline DNA for pharmacogenetics FOCUS (2135 pts) and CALGB/SWOG (2380 pts) have/are collecting germline DNA for pharmacogenetics

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