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348 Background: CapeOX is a standard regimen for treating advanced gastric cancer (AGC). However, limited data are available for its use in the elderly patients. Geriatric assessment (GA) assessment is also considered important other than the age. Therefore, we conducted a multicenter, single-arm, phase II study to evaluate the efficacy and safety of CapeOX as a first-line therapy for AGC in elderly patients. We performed GA assessments using the G8, and the MINI-COG. Methods: The inclusion criteria were: HER2-negative or unknown status, age 70 years or older, PS 0 or 1, no history of chemotherapy or radiotherapy, and an evaluable lesion based on the RECIST v1.1 guidelines. The initial treatment plan consisted of capecitabine (1,000 mg/m2, b.i.d., on days 1–14), and oxaliplatin (130 mg/m2, on day 1) every three weeks. After the initial feasibility assessment, the treatment plan was modified and consisted of capecitabine (750 mg/m2, b.i.d., on days 1–14) and oxaliplatin (100 mg/m2, on day 1) every three weeks. The primary endpoint was overall survival (OS). G8 assessments were performed before the beginning of the treatment, every three months after the start of the treatment, and at the end of the treatment. MINI-COG assessments were performed before the beginning of the treatment, and at the end of the treatment. Results: Between November 2016 and June 2020, 108 patients were enrolled, out of which 104 were evaluated. Thirty-nine patients received the initial treatment whereas sixty-five patients received the modified treatment. The primary endpoint was met. The median OS, progression-free survival (PFS), and time-to-treatment failure (TTF) were 12.9 (95% CI: 11.7–14.8), 5.8 (95% CI: 5.1–7.1), and 4.3 (95% CI: 3.9–5.7) months, respectively, for all patients. The median OS, PFS, and TTF for the initial treatment plan were 13.4 (95% CI: 9.6–16.0), 5.8 (95% CI: 4.1–7.9), and 5.3 (95% CI: 3.5–7.3) months, respectively, and for the modified treatment plan were 12.8 (95% CI: 11.3–15.3), 5.7 (95% CI: 4.4–7.0), and 4.2 (95% CI: 3.7–5.7) months, respectively. The most common grade 3/4 toxicities in the initial treatment plan patients were neutropenia (17.9%), anemia (12.8%), thrombocytopenia (12.8%), anorexia (10.3%), and nausea (10.3%) and in the modified treatment plan patients were (13.8%) and anorexia (12.3%). Mean G8 score was 11.4 before the treatment, 13.4 during the treatment and 11.6 at the end of the treatment. Mean MINI-COG score was 4.0 before the treatment, and 4.1 at the end of the treatment and the positive screen for dementia was 13.5% before the treatment and 11.4% at the end of the treatment. Conclusions: Our results show that the modified treatment plan is favorable for the elderly patients with gastric cancer based on the OS and the toxicities. Clinical trial information: 000022450 .

TPS1100 Background: Systemic chemotherapy with anti-HER2 therapy is the standard of care for HER2-positive advanced breast cancer. Patient outcomes have improved remarkably with the use of novel anti-HER2 drugs, including trastuzumab (H), pertuzumab (P), and trastuzumab emtansine (T-DM1). The combination treatment comprising H, P, and docetaxel (D) (HPD) is highly recommended as the 1st-line treatment for patients with HER2-positive advanced breast cancer. In contrast, for elderly patients over 65 years of age, this regimen seems to be intolerable mentally and physically, and impairs their quality of life. A new standard treatment with less toxicity and non-inferior efficacy for elderly patients is needed. Methods: We have planned a randomized, multicenter, open-label, phase III trial to confirm the non-inferiority of T-DM1 compared to HPD in terms of overall survival (OS) in elderly patients with HER2-positive advanced breast cancer. The eligibility criteria are as follows: 1) histologically proven metastatic breast cancer, 2) age 65-74 years with a performance status (PS) score 0-2, or 75-79 years with a PS score 0-1, 3) HER2 overexpression or amplification confirmed in primary or metastatic tissues, and 4) no anti-HER2 therapy with chemotherapy for breast cancer, excluding (neo) adjuvant therapy. Patients are randomized to receive either HPD (H 6 mg/kg, P 420 mg/body, and D 60 mg/m2) or T-DM1 3.6 mg/kg every 3 weeks. The dose up of D (75 mg/m2) after the second cycle is defined based on the data regarding safety during the first cycle. The primary endpoint is OS. The secondary endpoints are progression-free survival, response rate, adverse events, breast cancer-related death, and deterioration of activities of daily living. The trial is designed to achieve 70% power to confirm non-inferiority of T-DM1 to HPD at a one-sided alpha of 5% with a non-inferiority margin of 1.3 in terms of hazard ratio. With a median OS of 30 months in both arms, 6 years of accrual, and 5 years of follow up, the planned sample size is 330. The trial began in January 2018 and nineteen patients have been enrolled as of January 2019. Clinical trial information: UMIN000030783.

e15106 Background: Tumor mismatch repair (MMR) predicts benefit of immune checkpoint inhibitors (ICIs) in metastatic colorectal cancer (mCRC). We conducted a large-scale prospective observational trial on microsatellite instability (MSI) status in mCRC: SCRUM-Japan GI-SCREEN CRC-MSI. Methods: mCRC patients (pts) appropriate for systemic chemotherapy were eligible. Paired tumor and normal DNA extracted from FFPE samples were analyzed by the MSI Analysis System, which includes 5 mononucleotide markers. Tumors exhibiting ≥2 unstable markers were defined as MSI-H, while those with ≤1 were labelled MSI-L/MSS. Results: From 2/2016 to 3/2018, 1,711 pts were enrolled, and 1,696 samples were submitted. MSI status was determined in 1,676 pts (98.8%); 51 pts (3.0%) were MSI-H. For MSI-H vs. MSI-L/MSS pts: Median age (years) 64/64; male gender (%) 51.0 vs. 43.8, p=0.31; right-sided primary (%) 70.6 vs. 25.0, p20 mt/Mb, was observed in 27/29 (93.1%) MSI-H pts. The frequency of representative gene mutations (%) for MSI-H vs. MSI-L/MSS pts were: TP53 17.2 vs. 66.1, p

2519Background: The uptake of amino acids is essential for cancer growth. The L-type amino acid transporter 1 (LAT1) is overexpressed in various cancers, and the LAT1-mediated uptake of plasma-free...

419 Background: Uptake of amino acids is essential for cancer growth. L-type amino acid transporter-1 (LAT-1) is overexpressed in various cancers, and uptake of LAT-1 substrate amino acids is known to have a critical role in cancer growth. JPH203 is a novel, selective, LAT-1 inhibitor. A first-in-human phase I study of JPH203 was designed to determine the safety, maximum-tolerated dose (MTD) and recommended dose. This study included evaluation of the anti-tumor effect, pharmacokinetics, and pharmacodynamics of JPH203 and analyzed plasma free amino acids. Methods: JPH203 was administered intravenously for 7 days followed by 21 days’ rest at planned doses ranging from 12 to 110 mg/m2 in patients with advanced solid tumors refractory to standard therapy. Before starting this schedule, we confirmed safety of a single dose of JPH203. Dose-limiting toxicity was evaluated during the first cycle, using a 3+3 design. Results: 17 patients were enrolled from January 2015 to August 2016. One patient was discontinued after a single dose of JPH203 because of tumor progression. Dosage was escalated up to 85 mg/m2. Grade 3 liver dysfunction occurred in 1 of 6 patients at 60 mg/m2 and in the first patient at 85 mg/m2. Therefore, it was determined that MTD was 60 mg/m2. Common treatment-related adverse events were increased ALT/AST, malaise, nausea, hypertension and fever of Grade 1 or 2. Partial response was achieved in a patient with biliary tract cancer (BTC) who continued JPH203 for two years without progression. Disease control (PR+SD) was observed in 3 of 5 patients with BTC and 2 of 6 with colorectal cancer. LAT-1 substrate amino acids and branched chain amino acids including LAT-1 substrate amino acids were higher in patients with BTC than in those with other cancers. All patients with disease control had a body mass index more than the median of 20.5 kg/m2. In exploratory analysis, longer survival was achieved in patients with high inhibition of uptake of LAT-1 substrate amino acids, compared with patients with low inhibition of uptake. Conclusions: JPH203 was well tolerated, resulting in promise against BTC. This phase I study suggested that LAT-1 could be targeted in treatment for advanced BTC, because LAT-1 substrate amino acids in plasma tended to remain high. Clinical trial information: UMIN000016546.

310 Background: LEN inhibits the activity of vascular endothelial growth factor receptor, fibroblast growth factor receptor, and platelet-derived growth factor receptor–α. These targets have been shown to be expressed in patients (pts) with BTC. The objective of this study is to evaluate LEN as a potential treatment option for these pts. Methods: This is an open-label, phase 2 study conducted in Japan. Pts aged ≥ 20 years with confirmed diagnosis of unresectable BTC, measureable disease per Response Evaluation Criteria in Solid Tumors v1.1, and 1 prior gemcitabine-based doublet chemotherapy, will receive LEN 24 mg/d. The primary endpoint is objective response rate. Secondary objectives include disease control rate (DCR), safety, and pharmacokinetics. Enrollment of 25 pts is planned. The study includes an interim evaluation for futility. If there is no objective response and disease control is achieved in < 5 pts of 15‒17 pts, the study will end. Results: An interim evaluation was performed with 17 pts enrolled (data cutoff: 25 July 2016). Ten (59%) pts were aged < 65 years, 10 (59%) were male, 2 (12%) had prior surgery, and 13 (76%) received prior gemcitabine + cisplatin therapy. Efficacy results appear in the table. One pt had a partial response (PR) and 13 had stable disease (SD). The DCR was 82%. All pts experienced treatment-emergent adverse events (TEAEs). Grade ≥ 3 TEAEs occurred in 11 (65%) and serious AEs (SAEs) occurred in 7 (41%) pts. There were no fatal SAEs. TEAEs leading to LEN discontinuation, dose reduction, and dose interruption occurred in 1 (6%), 12 (71%), and 9 (53%) pts, respectively. Analysis of trough plasma concentration in 13 pts from this study showed no difference versus that observed in a previous phase 3 study of LEN in differentiated thyroid cancer. Conclusions: Because results of this interim evaluation did not meet futility criteria, the study was continued, with findings suggesting possible activity of LEN in pts with unresectable BTC who failed gemcitabine-based doublet chemotherapy. Toxicities were generally manageable with dose modifications as only 1 pt required discontinuation from LEN. Clinical trial information: NCT02579616. [Table: see text]

e17544 Background: Seeking a second opinion has become relatively common among patients with life-threatening diseases in Japan. We investigated the backgrounds and situations of patients with inop...

2544 Background: TAS-114 is a first-in-class oral deoxyuridine triphosphatase inhibitor, which acts as a modulator of the pyrimidine nucleotide metabolic pathway. We are conducting a first combinat...

4005 Background: RAINBOW, a global phase III trial, demonstrated significant improvements in overall survival (OS), progression-free survival (PFS), and objective response rate (ORR) in patients (p...

e20004 Background: Trametinib is a potent and selective allosteric MEK1/2 inhibitor. In Western countries, trametinib was investigated as monotherapy and in combination with various agents including gemcitabine in the studies with pancreatic cancer, melanoma and other types of cancer. According to these studies, the recommended dose (RD) and maximum tolerated dose (MTD) were determined as 2.0 mg QD and 3.0 mg QD respectively as monotherapy, and as 2.0 mg QD for both in combination with gemcitabine. The objectives of this study are to assess its tolerability and safety, and to evaluate the RD and the MTD in Japanese patients (pts). Methods: This open-label, dose-escalation study evaluated the tolerability/safety, pharmacokinetics (PK), and preliminary efficacy (RECIST) of trametinib alone (part 1) and in combination with gemcitabine (1000 mg/m2on Days 1, 8, and 15 of each 28-day cycle) (part 2) in Japanese pts with advanced solid tumors (NCT01324258). After confirming the tolerability and safety in part 1, part 2 was investigated. Results: (Part 1) Thirteen pts received trametinib at doses of 1.0 mg (n=4), 2.0 mg (n=6), and 3.0 mg (n=3). Various cancer types including melanoma were enrolled. One DLT (Grade 3 infectious pneumonia) was observed in part 1 in a subject at the 2.0 mg dose. The most common AE was Grade 1/2 rash (n=12). One PR (salivary gland cancer) and 3 long SDs (appendix cancer (n=1) and melanoma (n=2)) were observed. Preliminary PK results showed no obvious ethnic difference. (Part 2) Five pts with pancreatic cancer received trametinib (2.0 mg QD) in combination with gemcitabine. Although there was no DLT in the first 28 days (DLT observation period), interstitial lung disease (ILD) was observed in 3 pts after DLT observation period. Best responses were 3 PRs and 2 SDs. Conclusions: The RD (2.0 mg QD) and the MTD (3 mg QD) of trametinib that were determined in Western countries were tolerated in Japanese patients as monotherapy. In combination with gemcitabine, although trametinib was tolerated in the short term and showed promising antitumor efficacy, it is required to closely monitor patients for ILD while the combination is administered to patients. Clinical trial information: NCT01324258.

4647 Background: Lapatinib (GW572016) is a dual tyrosine kinase inhibitor of EGFR and HER2. In SWOG0413 trial, advanced or metastatic gastric cancer patients were treated with lapatinib. In this study, we investigated whether gene expressions and polymorphisms of EGF and angiogenesis pathway genes were associated with clinical outcome in the patients enrolled in SWOG0413 trial. Methods: A total of 46 patients were enrolled in SWOG0413 trial and treated with lapatinib. Blood and tissue samples were available from 42 and 37 patients, respectively. RT-PCR was performed for intratumoral gene expression levels of EGFR, HER2, VEGF, IL-8, COX2 and cyclin D1 genes. We also analyzed 8 polymorphisms in the EGF, EGFR, HER2, VEGF, IL-8, COX2 and cyclin D1 genes by PCR-RFLP. Results: Patients who have lower IL-8 [median overall survival (OS), 6 vs 3 months, p=0.03] and higher HER2 (6 vs 3 months, p=0.005) gene expression levels showed better OS. According to gene polymorphisms, patients who have A allele of IL-8 T251A polymorphism showed improved OS (A/A, 10 months vs T/A, 5 months vs T/T 3 months, p=0.04). And patients with A allele of IL-8 T251A and T allele of VEGF C936T polymorphisms showed better response rates (p [Table: see text]

4122 Background: There is increasing evidence that gender plays a significant role in the development and progression of colorectal cancer (CRC). Rates of CRC incidence are higher among males, and it has been shown that hormone replacement therapy in postmenopausal women reduces the risk of developing CRC, indicating a protective effect of female hormones. These findings indicate that physiological differences between the sexes may contribute to differential tumor development and progression. In the current study, we tested the hypothesis whether males and females would have different genomic profiles that would predict clinical outcome in 5-FU/oxal-treated mCRC. Methods: One hundred seventy-three patients were enrolled in this phase II study. One hundred fifty-two patients were evaluable for genotyping and statistical analysis. There were 74 females and 78 males, and median age was 60 (range 25–87). Twenty-four polymorphisms in 12 genes involved in cancer progression were tested by PCR. CART analysis was used to test for association of polymorphisms with overall survival (OS), time to tumor progression (TTP), and tumor response. Separate regression trees were developed for males and females. Results: Median follow-up was 18.6 months, response rate 19%, median time to tumor progression 4.2 months and median survival 10.3 months. CART analysis by gender generated significantly different regression trees for men versus women. For TTP, males carrying polymorphisms in the ER-β and SCN1A genes had improved TTP, while females carrying polymorphisms in the XPD and EGFR genes had improved TTP. For OS, male patients carrying ER-β and MTHFR polymorphisms had improved OS, while female patients carrying polymorphisms in SCN1A and PLA2 had improved OS. It is notable that analysis of males and females in combination produced a different regression tree than when separated by gender. Conclusions: Our results suggest for the first time that genomic profiling to predict clinical outcome of patients with mCRC depends on gender. Taking gender into account when examining the genetic profile of patients may help to more specifically identify those who will benefit from 5-FU/oxal chemotherapy. No significant financial relationships to disclose.

4004 Background: Despite recent advances in the treatment of metastatic colorectal cancer, tailoring adjuvant treatment of stage II and III colon cancer patients remains controversial. Identifying a reliable panel of prognostic and predictive markers for tumor recurrence is critical in selecting an individualized and tailored chemotherapy. Tumor angiogenesis plays an important role in tumor development, progression and metastasis. In this retrospective study, we tested whether a specific pattern of 40 functionally significant polymorphisms in 37 genes involved in angiogenesis and tumor microenvironment will predict the risk of tumor recurrence in stage II and III colon cancer patients treated with adjuvant chemotherapy. Methods: Between 1999 and 2006 blood specimens from 140 patients (69 females and 71 males with a median age of 59 years; range=28–86) were obtained at the University of Southern California/Norris Comprehensive Cancer Center (USC/NCCC). Sixty-three patients had stage II and 77 had stage III colon cancer. The median follow-up was 5.4 years (range=2.0–16.8). 51 of 140 patients (36.4%) developed tumor recurrence with a 5-year probability of 0.28 ± 0.06 for stage II and 0.40 ± 0.06 for stage III colon cancer patients. Genomic DNA was extracted from peripheral blood and genotypes were determined using PCR based RFLP. Results: Polymorphisms in VEGF (C936T; p=0.009, log-rank) and VEGFR2 (+4422 AC- repeat; p=0.04, log-rank and +1416 T/A; p=0.0009, log-rank) were associated with risk of tumor recurrence in stage III colon cancer patients (n=77). VEGFR2 AC-repeat polymorphisms were additionally associated with risk of recurrence in Stage II colon cancer patients (n=63, p=0.02, log-rank). Conclusion: VEGF C936T and VEGFR2 (+4422 AC-repeat and +1416 T/A) polymorphisms may help to identify Stage II and III colon cancer patients who are at increased risk for developing tumor recurrence. Angiogenesis seems to play a crucial role in tumor recurrence, thus targeting VEGF and VEGFR2 may be of clinical benefit for stage II and stage III colon cancer patients. Large prospective trials are needed to validate these preliminary data. No significant financial relationships to disclose.

2504 Background: S-1, which is an oral anticancer agent comprised of FT, CDHP and potassium oxonate, is one of the most widely prescribed agents in the treatment of gastric and colorectal cancer in Japan. CYP2A6 is involved in the bioactivation of FT to 5-FU. Dihydropyrimidine dehydrogenase which is responsible for the detoxification of 5-FU is inhibited by CDHP to increase plasma exposure of 5- FU. The dose of S-1 is determined by body surface area (BSA) of the patients. We prospectively analyzed contribution of CYP2A6 genotype, plasma level of CDHP, and BSA on the PK of FT and 5-FU. Methods: Forty Japanese patients with metastatic/ recurrent cancers who received S-1 were enrolled. Genetic polymorphisms in CYP2A6 (*4, *7 and *9) related to deficient or reduced activity were analyzed. CYP2A6 genotypes were defined as wild (*1/*1), one-reduced allele (*1/*4, *1/*7 or *1/*9) and two-reduced alleles (*4/*4, *4/*7, *4/*9, *7/*7, *7/*9 or *9/*9). On the first day of the treatment, plasma concentration of FT, 5-FU and CDHP were measured. Multivariate linear regression analysis was used identifying association or correlation between oral clearance (CL/F) for FT or area under the time-concentration curve (AUC) for 5-FU and possible factors including CYP2A6 genotype, AUC for CDHP and patient’s characteristics including BSA. Results: CL/F for FT was significantly associated with CYP2A6 genotype (ANOVA, P=0.0000787, R2=50.1%), but not with other factors. CL/F for FT in patients with one- and two-reduced allele(s) were significantly lower than that in wild patients (P=0.0126 and 0.000128, respectively; Wilcoxon test). AUC for 5-FU was significantly correlated with AUC for CDHP (ANOVA, P=0.000534, R2=39%), but not with others. AUC for CDHP was correlated with creatinine clearance (Ccr) (ANOVA, P=0.00056, R2=27.2%). Conclusions: PK of FT and 5-FU are significantly affected by CYP2A6 genotype and exposure of CDHP, respectively. In addition, AUC for CDHP, which is correlated with Ccr, is the more critical factor to regulate AUC for 5-FU than BSA. Ccr-based dosing will be more rational than the conventional BSA-based dosing in the prescription of S-1. No significant financial relationships to disclose.

4108 Background: Tissue Factor (TF), a transmembrane glycoprotein, initiates the physiologic coagulation cascade. Cumulative evidence implies that TF plays a key role in tumor angiogenesis. Elevated TF expression has been reported to be associated with poor survival in patients in solid tumor. We investigated whether a functional TF promoter polymorphism -603 A/G is a prognostic factor in patients with advanced colon cancer because the G allele had been linked to high constitutive TF gene expression in human monocytes in healthy volunteers. Methods: 318 patients with metastatic colon cancer treated at the USC/Norris Comprehensive Cancer Center or the LA County/USC Medical Center during 1992 through 2003 were included in this study. Genomic DNA was extracted from white blood cells of peripheral blood samples using the QiaAmp kit (Qiagen, Valencia, CA). The TF polymorphism was genotyped by PCR-RFLP-based approach. The association between the TF polymorphism and overall survival was examined using the log-rank and trend test. The association between TF polymorphism and baseline demographic characteristics was tested using the χ2 test or Fisher’s exact test when appropriate. Results: There were 141 females and 177 males, with a median age of 58 years (range 25–86). The cohort comprised 234 whites, 43 Asians, 15 Blacks, 24 Hispanics, and 2 Native Americans. The median survival was 13.7 months with a median follow-up of 2.3 years. Asians were less likely to bear the G allele compared to other racial groups (P < 0.001, Fisher’s exact test). Patients who carried 1 or 2 G alleles were at higher risk of poor survival compared to patients with no G alleles (A/A) (P = 0.038, trend test). The median overall survival was 14.7 vs. 11.9 months for patients with A/A vs. patients with G/G or A/G, respectively. Conclusions: This study suggests that TF may be a prognostic factor for patients with metastatic colon cancer. The finding should be validated with future prospective clinical studies. No significant financial relationships to disclose.

4129 Background: A phase II study of cetuximab (IMCL-0144) has shown response rate of 12 % in patients with EGFR expressing metastatic colorectal cancer (mCRC). Recently, we reported that polymorphisms in the EGFR pathway may be useful molecular markers to predict clinical outcome. In this larger study, we tested whether polymorphisms in genes involved in the EGFR and angiogenesis pathway will be associated with clinical outcome. Methods: We analyzed 136 tissue samples from 346 mCRC pts enrolled in the phase II study of cetuximab (IMCL-0144), 133 cases were informative. The response rate in these 133 pts was 10% with a median progression-free survival (PFS) of 1.3 months (95% CI, 1.2 to 1.5) and an overall survival time (OS) of 5.5 months (95% CI, 4.1 to 7.5). Gr3–4 toxicity was observed in 56%. Gene polymorphisms of EGFR, Cox-2, EGF, cyclin D1, fragment c γ receptor 2A (FCGR2A), FCGR3A, VEGF, IL-8 were assessed from gDNA extracted from tissue samples by using PCR-based RFLP technique. Univariate analysis (Fisher’s exact test for response; log-rank test for PFS and OS) was performed to examine associations between polymorphisms and clinical outcome. A classification and regression tree (CART) analysis was used to identify subgroups of patients who were more likely to benefit from cetuximab. Results: Pts with EGFR G497C GA, Cox-2 G-765C CC, EGF A61G GG genotype showed better PFS (p=0.02, 1.8mo. vs. 1.2mo.; p=0.03, 6.9mo. vs. 1.3mo.; p=0.04, 1.4mo. vs. 1.2mo.), respectively. We found trends in associations between Cox-2 and tumor response (p=0.09), between EGF and Gr3–4 toxixity (p=0.06). CART analyses indicated that germline polymorphisms in EGFR, EGF, Cox-2, Cyclin D1, IL-8, FCGR2A and FCGR3A genes could be used to identify patients who benefit most likely of cetuximab therapy. Conclusions: Our data suggest that the polymorphisms of EGFR, Cox-2, and EGF may be useful molecular markers to predict clinical outcome in mCRC pts treated with single-agent cetuximab. And prospective studies will need to be done to confirm these preliminary findings. [Table: see text]

4130 Background: Many factors contribute to the progression of colorectal cancer and to chemoresistance. Two factors that have recently gained attention are angiogenesis and sex hormones. Interleukin-8 and its receptors play a critical role in angiogenesis, and polymorphisms in these genes have previously been reported to predict clinical outcome and resistance to therapy in a variety of cancer types. In addition, gender and the subsequent varied levels of sex hormones between males and females may also have an impact on colorectal cancer progression. Sex hormones such as estrogen exert their effects on the cell by binding to steroid receptors such as estrogen receptor beta (ER-β). It is known that ER-β is predominantly expressed in the colon, and that differential expression of this gene is predictive of clinical outcome. Therefore, functional polymorphisms within ER-β, IL-8, and the IL-8 receptors may prove to be molecular markers for predicting clinical outcome in colorectal cancer patients. Methods: 173 patients were enrolled in this phase II study. 152 patients were evaluable for genotyping and statistical analysis. There were 74 females and 78 males, and median age was 60 (range 25–87). The dose of oxaliplatin was 130mg/m2 every 3 weeks and 5-FU was 200mg/m2/day CI for 10 weeks followed by 2 weeks rest. Polymorphisms in estrogen receptor beta, IL-8, and CXCR2 (IL-8 receptor) were tested by PCR. Results: Median follow-up was 18.6 months, response rate 19%, median time to tumor progression 4.2 months and median survival 10.3 months. IL-8 T251A polymorphism was predictive of time to tumor progression (p=0.04, log-rank test). ER-β CA repeat polymorphism was predictive of tumor response as well as time to tumor progression (p=0.015, p=0.012, respectively). ER-β A730G SNP was also predictive of time to tumor progression (p=0.03). Polymorphism in CXCR2 was predictive of tumor response (p=0.034). Conclusions: Our results suggest that polymorphisms within IL-8, CXCR2, and ER-β may affect the progression of colorectal cancer and subsequent clinical outcome. These results highlight the importance of angiogenesis and hormone levels in colorectal cancer. No significant financial relationships to disclose.

13078 Background: Pharmacogenetic testing of UGT1A1*28, a promoter variant of UGT1A1 gene, for estimating a risk of irinotecan toxicity has been introduced into clinical practice. Purpose: To elucidate clinical significance of UGT1A1*6 and UGT1A1*27, the variants in exon 1 that are found mostly in Asians. Methods: Pharmacogenetic relationships were explored between the genotyping results and ratio of area under the concentration-time curve (AUC) of SN-38 and its glucuronide (SN-38G) as a surrogate for a UGT1A1 activity (AUCSN-38/AUCSN-38G) in 36 Japanese patients who received various regimens of irinotecan chemotherapy at doses from 50 to 180 mg/m2. Results: No patients were homozygous for UGT1A1*28 and none had UGT1A1*27. One was heterozygous for UGT1A1*28. Two were homozygous and ten heterozygous for UGT1A1*6, all of whom were wild type with respect to UGT1A1*28. Two patients were simultaneously heterozygous for UGT1A1*28 and UGT1A1*6 that existed on the different chromosomes. The remaining 21 patients did not have any variants studied. The 2 patients who was simultaneously heterozygous for UGT1A1*28 and UGT1A1*6 and the 2 patients who were homozygous for UGT1A1*6 had significantly higher AUCSN-38/AUCSN-38G than the others (P = 0.004). Conclusions: Concurrence of the two UGT1A1 variants, UGT1A1*28 and UGT1A1*6 even in their heterozygous statuses, remarkably altered drug disposition of irinotecan and could enhance susceptibility to the drug. Patients who are homozygous for UGT1A1*6 should also be monitored cautiously. Genotyping of UGT1A1 polymorphisms in the coding region together with UGT1A1*28 is necessary for predicting irinotecan toxicity at least for Asian patient population. [Table: see text] [Table: see text]

3600 Background: Methylenetetrahydrofolate Reductase (MTHFR) is a key enzyme regulating intracellular folate pool, which affects DNA synthesis and methylation. Recent studies found folate deficiency induces DNA damage because of impaired nucleotide-excision repairs in mouse model. Two MTHFR gene polymorphisms, C677T and A1298C are linked to altered enzyme activity. Numerous studies have shown these two polymorphisms associated with colon cancer risk and response to fluorouracil-based treatment in advanced colon cancer patients. One epidemiology study also demonstrated 1298CC genotype to be associated with a significantly lower risk of colon cancer in women, but not men. We tested whether these two polymorphisms were associated with clinical outcome in metastatic colon cancer patients treated with 5-FU/Oxaliplatin. Methods: Between 1992 and 2003, a total of 318 patients with metastatic colon cancer treated at the University of Southern California/Norris Comprehensive Cancer Center (USC/NCCC) or the Los Angeles County/University of Southern California Medical Center (LAC/USCMC), were eligible for this study. Peripheral blood samples were collected from each patient and genomic DNA was extracted from white blood cells using the QiaAmp kit (Qiagen, Valencia, CA). Two MTHFR gene polymorphisms (C677T, A1298C) were tested by PCR-RFLP method. Results: MTHFR A1298C gene polymorphism showed statistically significant differences in overall survival (OS) in female patients with metastatic colon cancer (P=0.025, logrank test). Patients with the AA genotype had an 18.7 months median OS compared with the heterozygous AC genotype, which had a 14.3 months median OS and the CC genotype, which had a 15.9 months median OS. Conclusions: There is no significant difference in clinical outcome in male patients. However, female metastatic colon cancer patients with a MTHFR A1298C polymorphism AA genotype have significantly better overall survival than those with heterozygous AC genotype or CC genotype. This data supports the role of MTHFR polymorphisms as an independent prognostic marker in female patients with metastatic colon cancer. Further prospective study is needed to confirm these preliminary findings. [Table: see text]

3028 Background: Cetuximab is a chimeric immunoglobulin G1 anti-EGFR monoclonal antibody with efficacy in metastatic colorectal cancer patients refractory to irinotican chemotherapy. Recent studies show that Antibody-dependent cellular cytotoxicity (ADCC) mediated through Fc receptors plays an important role in the antitumor effect of IgG1 antibody. There are three classes of FcγRs involved in the regulation of ADCC. FcγRIIa(CD32) and FcγRIIIa(CD16) activates and FcγRIIb inhibits activation. Clinical studies show FcγRIIIa 158 V/F polymorphism was associated with tumor response and progression-free survival in the follicular lymphoma patients treated with rituximab as first line treatment. Also, a H/R polymorphism at position 131 of FcγRIIa has been found to affects its affinity to human IgG and independently predict response to Rituximab. Since Cetuximab and Rituximab belong to the same chimeric IgG1 monoclonal antibody, we test hypothesis whether these two FcγR polymorphisms associated with clinical outcome in colorectal cancer patients treated with single agent Cetuximab. Methods: we tested both FcγRIIIa 158 V/F and FcγRIIa 131 H/R gene polymorphisms using PCR-RFLP method in genomic DNA extracted from peripheral blood from 39 EGFR-expressing metastatic colorectal cancer patients enrolled in a phase II single agent Cetuximab treatment clinical trial (IMCL-0144). Results: We found patients with FcγRIIa 131 HH or HR genotype show better time to progression and overall survival compare to patients with R/R genotype (p=0.037, p=0.22, respectively, log-rank test). Also, there is trend significance in tumor response when we compare patients with RR genotype and patients with HH or HR genotype (p=0.08, fisher’s exact test). FcγRIIIa 158 V/F also show trend significance in tumor response (p=0.067, fisher’s exact test). Conclusions: These data suggest Two Immunoglobulin G Fragment C Receptor polymorphismsFcγRIIIa158V/F andFcγRIIa 131 H/R may be potential molecular markers for clinical outcome of refractory metastatic colorectal caner patients treated with single agent EGFR inhibitor Cetuximab. Prospective studies are needed to confirm these preliminary findings. [Table: see text]

3533 Background: Genetic polymorphisms in DNA repair and drug metabolism pathways have been shown to be associated with efficacy and toxicity in patients with metastatic colon cancer treated with 5-FU/oxaliplatin. Recent studies demonstrated in in vitro models that the neurotoxicity associated with oxaliplatin may be linked to an effect on neuronal voltage-gated sodium channels (VGSC). In vitro and in vivo models showed that increased VGSC alpha gene expression was associated with metastatic potential, proliferation and progression of breast and prostate cancer indicating a role in predicting toxicity and efficacy to chemotherapy. We tested the hypothesis whether VGSC gene polymorphisms may predict clinical outcome in a phase II study of combination oxaliplatin with 5-FU in patients with colorectal cancer refractory to 5-FU and/or irinotecan based chemotherapy. Methods: 173 patients were enrolled in this phase II study. 152 patients (male/female; 78/74, median age; 60), median follow up of 18.6 months, response rate of 19%, median time to tumor progression 4.2 months and median survival of 10.3 months. Grade 3/4 toxicity was seen in 60% with GI toxicity of 42% and Neurotoxicity of 11%. The dose of oxaliplatin was 130mg/m2 every 3 weeks and 5-FU was 200mg/m2/day CI for 10 weeks followed by 2 weeks rest. We tested the 12 VGSC genes polymorphisms (SCN1A, 1B, 1A1, 1A2, 1A3, 1A4, 1A5, 1A A3169G SNP, 1A C1702T Nonsense Mutation, 1A T1067A SNP, 1A C3637T SNP, SCN8A Ref SNP 303802). Genomic DNA was extracted from peripheral blood samples and polymorphisms were analyzed by PCR-based RFLP technique. Results: Patients with SCN1A T1067A SNP T/T genotype showed a significant better response rate (p=0.02, 21.9% [23/105] vs. 11.3% [5/44]), TTP (p=0.02, 4.6 months vs. 3.4 months), overall survival (p [Table: see text]