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PURPOSE The phase III ACHIEVE trial conducted in Japan was one of six prospective studies included in the International Duration Evaluation of Adjuvant Therapy collaboration, which explored whether 3 months of adjuvant fluorouracil, leucovorin, and oxaliplatin (FOLFOX) or capecitabine and oxaliplatin (CAPOX) therapy would be noninferior to 6 months of treatment in patients with curatively resected stage III colon cancer. We report the final analyses of survival and long-term safety. PATIENTS AND METHODS Eligible patients were randomly assigned (1:1) to either 3 or 6 months of adjuvant chemotherapy (modified [m]FOLFOX6 or CAPOX, as selected by the treating physician). Random assignment was stratified according to number of involved lymph nodes, center, regimen, primary site, and age. The primary end point was disease-free survival, assessed in the modified intention-to-treat population. Overall survival (OS) was a secondary end point. RESULTS The modified intention-to-treat population comprised 1,291 patients: 641 in the 6-month treatment group and 650 in the 3-month treatment group. Median follow-up for this analysis was 74.7 months. Five-year OS rates were comparable: 87.0% in the 3-month treatment group and 86.4% in the 6-month treatment group (hazard ratio, 0.91; 95% CI, 0.69 to 1.20; P = .51). Subgroup analysis of OS did not reveal a significant interaction between baseline characteristics and treatment duration. Peripheral sensory neuropathy lasting longer than 5 years was more common in the 6- compared with 3-month treatment group (16% v 8%, respectively), and in those receiving mFOLFOX6 compared with CAPOX (14% v 11%, respectively). CONCLUSION In Asian patients, shortening adjuvant therapy duration from 6 to 3 months did not compromise efficacy and reduced the rate of long-lasting peripheral sensory neuropathy. In this setting, 3 months of CAPOX therapy is an appropriate adjuvant treatment option.

PURPOSE Treatment with an aromatase inhibitor for 5 years is the standard treatment for postmenopausal hormone receptor–positive breast cancer. We investigated the effects of extending this treatment to 10 years on disease-free survival (DFS). PATIENTS AND METHODS This prospective, randomized, multicenter open-label phase III study assessed the effect of extending anastrozole treatment for an additional 5 years in postmenopausal patients who were disease-free after treatment with either 5 years of anastrozole alone or 2-3 years of tamoxifen followed by 2-3 years of anastrozole. Patients were allocated randomly (1:1) to continue anastrozole for an additional 5 years or stop anastrozole. The primary end point was DFS, including breast cancer recurrence, second primary cancers, and death from any cause. This study is registered with University Hospital Medical Information Network, Japan (UMIN) clinical trials registry (UMIN000000818). RESULTS We enrolled 1,697 patients from 117 facilities between November 2007 and November 2012. Follow-up information was available for 1,593 patients (n = 787 in the continue group, n = 806 in the stop group), who were defined as the full analysis set, including 144 patients previously treated with tamoxifen and 259 patients who underwent breast-conserving surgery without irradiation. The 5-year DFS rates were 91% (95% CI, 89 to 93) in the continue group and 86% (95% CI, 83 to 88) in the stop group (hazard ratio, 0.61; 95% CI, 0.46 to 0.82; P < .0010). Notably, extended anastrozole treatment reduced the incidence of local recurrence (continue group, n = 10; stop group, n = 27) and second primary cancers (continue group, n = 27; stop group, n = 52). There was no significant difference in overall or distant DFS. Menopausal or bone-related all-grade adverse events were more frequent among patients in the continue group than those in the stop group, but the incidence of grade ≥3 adverse events was CONCLUSION Continuing adjuvant anastrozole for an additional 5 years after 5 years of initial treatment with anastrozole or tamoxifen followed by anastrozole was well tolerated and improved DFS. Although no difference in overall survival was observed as in other trials, extended anastrozole therapy could be one treatment choice in postmenopausal patients with hormone receptor–positive breast cancer.

PURPOSE Genomic profiling programs have been implemented to apply next-generation sequencing (NGS) for facilitating trial enrollment. SCRUM-Japan GI-SCREEN is a large-scale genomic profiling program in advanced gastrointestinal cancers using a validated genomic assay with the goal of facilitating enrollment in targeted clinical trials, generating real-world data, and performing clinicogenomic analysis for biomarker discovery. PATIENTS AND METHODS Genotyping of tumor tissue samples from 5,743 patients with advanced gastrointestinal cancers enrolled in GI-SCREEN was centrally performed with NGS. Patients were enrolled in matched trials of targeted agents affiliated with GI-SCREEN on the basis of genotyping results. RESULTS A total of 11 gastrointestinal cancers were included, with colorectal cancer being the most common. The median age ranged from 59 to 70.5 years across cancer types. Patients enrolled after initiation of first-line treatment had significantly longer overall survival (OS) than that before treatment initiation with a median survival time difference of 8.9 months and a hazard ratio (HR) ranging from 0.25 to 0.73 across cancer types, demonstrating an immortal time bias. One hundred and forty-nine patients received matched therapies in clinical trials on the basis of their identified alterations. Among patients with colorectal cancer harboring actionable alterations, the median OS was significantly longer in patients who received matched therapies in trials than in those who did not (HR, 0.52; 95% CI, 0.26 to 1.01; P = .049). Cancer-specific pathway alterations were significantly associated with shorter survival and related to primary resistance to matched trial therapies. CONCLUSION Our genomic profiling program led to patient enrollment in targeted clinical trials and improved survival of patients with colorectal cancer who received matched therapies in clinical trials. To avoid immortal time bias, precautions are needed when using data from patients who have undergone NGS testing after initiation of the evaluated treatment line.

3555 Background: HER2 amp occurs in 1-4% of mCRC pts. Two single arm phase 2 studies, HERACLES and MyPathway, showed efficacy for dual HER2-targeted therapy in pts with RAS wild type ( RAS wt) mCRC with HER2 amp detected in tumor tissue; however, efficacy for pts prospectively enrolled with HER2 amp identified in ctDNA is unknown. Furthermore, the efficacy of real-world non-HER2-targeted SOC for HER2 amplified RASwt mCRC pts is not clear. Methods: We conducted a phase 2 trial to evaluate the efficacy of pertuzumab (P) plus trastuzumab (T) in RASwt mCRC pts with HER2 amp centrally confirmed by tissue (IHC and/or FISH) and/or ctDNA (Guardant360) who had progressed on SOC including EGFR blockade. Pts received intravenous P (840 mg loading dose followed by 420 mg) and T (8 mg/kg loading dose followed by 6 mg/kg) every 3 weeks. The primary endpoint was confirmed objective response rate (ORR) by investigator assessment, analyzed for two primary populations: pts with HER2 amp in tissue (tissue+) or in ctDNA (ctDNA+). Efficacy of real-world non-HER2-targeted SOC for HER2 amplified RASwt mCRC pts was prospectively assessed in a concurrent registry: the SCRUM-Japan registry. Results: Among 75 pts screened, concordance of HER2 amp between tissue and ctDNA was 83%. The primary endpoint was met in each cohort of TRIUMPH, with confirmed ORR of 30% (95% CI 14-50%) in 27 tissue+ pts and 28% (12-49%) in 25 ctDNA+ pts. In contrast, ORR in first salvage SOC after EGFR blockade was 0% (0.0-24.7%) in the real-world cohort. Median progression free and overall survival were 4.0 months (1.4-5.6) and 10.1 months (4.5-16.5) in the tissue+ pts and 3.1 months (1.4-5.6) and 8.8 months (4.3-12.9) in the ctDNA+ pts. One pt withdrew due to an adverse event (grade 3 decreased ejection fraction), but no treatment related deaths occurred. In exploratory analyses, pts without ctDNA mutations of RAS/ BRAFV600/ PIK3CA/ HER2 were more likely to respond to P+T than those with a ctDNA mutation in at least one of these genes (ORR 44% vs. 0% in tissue+ and 37% vs. 0% in ctDNA+). Decreased ctDNA fraction and HER2 plasma copy number at 3 weeks after treatment initiation corresponded to P+T response. At least one actionable alteration emerged after progression in 16 (62%) of 26 pts with ctDNA results at both baseline and progression. Among 5 pts who achieved response and had ctDNA results at both time points, 4 pts acquired actionable alteration at progression. Conclusions: We demonstrate promising efficacy and safety of P+T for RASwt mCRC pts with HER2 amp in either tumor tissue or ctDNA. Our results show that complete ctDNA genotyping identifies pts most likely to benefit from dual HER2 blockade and can be used to monitor response and detect actionable resistance biomarkers. Clinical trial information: UMIN000027887 and UMIN000028058.

60 Background: Colorectal cancer (CRC) incidence and mortality have decreased since the 1970s but several data such as the SEER CRC registry show that the incidence of early onset colon cancer (eoCC, age 20-49) and RC keep increasing. There is limited results suggesting eoCC may have different behaviors compared to traditional CC (tCC, age ≥ 50). Methods: Individual patient data of 1,805 high-risk stage II/III colon cancer (CC) patients (pts) as the modified ITT population in ACHIEVE and ACHIEVE-2 trials were investigated. Clinicopathological features and treatment-related data were assessed by age group. Disease-free survival (DFS) was assessed by Kaplan-Meier curves and Cox multivariable models adjusted by trials, regimen, T and N. Results: Of the 1,805 pts, eoCC were 155 pts (8.6%). Using 5% difference between age groups as clinically meaningful cutoff, eoCC had similar gender (female, 52 vs 48%), PS (PS = 1, 1 vs 4%), risk group (high-risk, 43 vs 42%) and T stage (T4, 30 vs 30%) as tCC, while eoCC were less likely right-sided colon primary (32 vs 39%), had N1 disease (48 vs 54%), and treated by FOLFOX (16 vs 23%). Overall, eoCC significantly had a worse DFS than tCC (3y-DFS, 75 vs 82%; Adjusted Hazard Ratio = 1.40: 95% Confidence Interval, 1.00-1.95: p= 0.0478); in addition, similar DFS were observed among tCC pts (age 50-69 vs >70). eoCC experienced less neutropenia, thrombocytopenia and stomatitis, but had more diarrhea, nausea and/or vomiting. There were 38 and 297 pts with an initial relapse in eoCC and tCC, respectively. Of those, peritoneal metastases were more frequently seen in eoCC (n = 13, 34%) than in tCC (n = 63, 21%) (p = 0.097), whereas liver and lung metastases were similar between the two groups. Impact on DFS of 3 versus 6 months of adjuvant chemotherapy in eoCC (3y-DFS, 75% vs 76%) is similar to that in tCC (83% vs 81%). Conclusions: eoCC had unique characteristics; the difference in DFS between eoCC and tCC were potentially due to a different metastatic spread. eoCC had a different adverse event profile compared to tCC. No impact on DFS of treatment duration in eoCC was suggested. Clinical trial information: UMIN000013036.

207 Background:ATTRACTION-1/ONO-4538-07 (AT-1), an open-label, single-arm, multicenter phase 2 clinical trial conducted in Japan, evaluated the clinical activity and safety of nivolumab in patients with advanced esophageal squamous cell carcinoma (ESCC) refractory/intolerant to fluoropyrimidine-, platinum-, and taxane-based chemotherapy. We previously reported the 2-year follow-up findings of AT-1, in which nivolumab demonstrated antitumor activity with a manageable safety profile for these patients. Here we report the final findings from AT-1 at a minimum follow-up of 5 years. Methods:Patients aged ≥20 years with an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-1 received 3 mg/kg nivolumab intravenously every 2 weeks in 6-week cycles until disease progression or unacceptable toxicity. The primary endpoint was centrally-assessed objective response rate (ORR), defined as the proportion of patients whose best overall response was either a complete or partial response. Secondary endpoints included overall survival (OS), investigator-assessed ORR, progression-free survival (PFS), change in tumor burden, time to response, time to disease progression, and duration of response. Results:Between February 25 and November 14, 2014, a total of 65 patients were enrolled. Sixty-four patients were evaluated for the efficacy, and all patients were evaluated for the safety. At the final database lock on August 6, 2020, 11 (17.2%, 95% confidence interval [CI] 9.9-28.2) of 64 patients had an objective response by central assessment. The median OS was 10.8 months (95% CI, 7.4-13.9), and the estimated 5-year OS rate was 6.3% (95% CI, 2.0-14.0). The median PFS was 1.5 months (95% CI, 1.4-2.8), and the estimated 5-year PFS rate was 6.8% (95% CI, 2.2-15.1). Treatment-related adverse events that occurred with a frequency of > 10% were diarrhea and rash. The presentation will include characteristics of long-term survivors as well as detailed efficacy and safety data of nivolumab. Conclusions:This final assessment represents the longest follow-up of patients with advanced ESCC treated with nivolumab. Nivolumab demonstrated continued long-term efficacy in these patients based on a minimum of 5-year long-term survival update of AT-1. Furthermore, no new safety signals with nivolumab were identified during long-term follow-up. These findings are consistent with those of nivolumab monotherapy for various types of cancer. Clinical trial information: No.142422.

4071 Background: We recently reported that ctDNA genotyping had advantages compared with tumor tissue testing in terms of enrollment to matched clinical trials across a wide range of GI cancers (Nakamura Y, et al. ASCO-GI 2020). Here, we investigated the utility of ctDNA genotyping in mCRC in a SCRUM-Japan GI-SCREEN and GOZILA combined analysis. Methods: In GI-SCREEN, tumor tissue genotyping was performed using a next generation sequencing (NGS)-based assay, Oncomine Comprehensive Assay since Feb 2015. In GOZILA, NGS-based ctDNA genotyping was performed using Guardant360 since Feb 2018. All tests were conducted centrally in a CLIA-certified and CAP-accredited laboratory. Patients with actionable alterations were enrolled into matched company-sponsored or investigator-initiated interventional clinical trials. Results: As of Apr 2019, 2,791 mCRC patients (2,754 eligible for analysis) in GI-SCREEN and 470 (464 eligible for analysis) in GOZILA were enrolled. There were no significant differences in baseline patient characteristics between GI-SCREEN and GOZILA. Most of trials affiliated with GI-SCREEN (81%) or GOZILA (78%) targeted the RTK/RAS/RAF pathway. Compared with tumor testing, ctDNA genotyping significantly improved turnaround time (median, 12 vs. 34 days, P < 0.0001), sequencing success rate (96.1 vs. 92.3%, P = 0.002), and detection rate of actionable alterations (73.3 vs. 62.2%, P = 0.02). Among patients with actionable alterations, enrollment to matched clinical trials was achieved in 5.0% in GI-SCREEN and 12.1% in GOZILA ( P < 0.0001). Median time from enrollment in the respective screening study to enrollment in a matched clinical trial was 6.5 months in GI-SCREEN and 0.9 months in GOZILA, respectively ( P < 0.0001). Objective response rate and progression-free survival were similar in both groups (tissue vs. ctDNA; ORR: 18.8 vs. 17.1%, P = 1.00; median PFS: 2.2 vs. 2.2 months, HR=1.05 [95% CI, 0.71–1.55], P = 0.79). Conclusions: For patients with mCRC, ctDNA genotyping had advantages over tissue genotyping with shorter turnaround time and higher sequencing success and actionable alteration detection rate, which were associated with improved clinical trial enrollment without compromising the efficacy. Funding: SCRUM-Japan Funds. Clinical trial information: UMIN000029315 .

4543 Background: Treatment (tx) of advanced gastric cancer (GC/GEJ) is highly heterogeneous, with substantial variability in tx patterns. Frontline tx choice may affect outcomes of subsequent tx, thereby influencing choice/efficacy of second-line (2L) tx. In RAINBOW, 2L ramucirumab(R) plus paclitaxel(P) significantly improved overall survival (OS) of patients (pts) with GC/GEJ. Here we explore efficacy, safety and quality of life (QoL) based on prior tx. Methods: Pts were grouped into doublet (DB) or triplet (TP) regimens based on prior cytotoxic tx received. OS and PFS were estimated using Kaplan-Meier method and tx effects on OS and PFS were evaluated by Cox PH model; safety and QoL were assessed descriptively for DB vs TP. Results: Use of DB and TP was similar between arms, with 23% in R+P and 26% in placebo (PB)+P arm receiving TP. Baseline characteristics were generally balanced between tx arms within DB and TP subgroups, with majority of TP administered in western regions (91%). Pts ≥65 years of age was 40% for DB and 28% for TP. DB pts (n = 498; 75%) received S1+cis (n = 97, 15%) and cape+ox (n = 71; 11%) as most common prior tx, while TP pts (n = 163; 25%) received epi+cape+ox (n = 74, 11%) and epi+cis+5FU (n = 53, 8%). Similar to ITT population, R+P improved OS and PFS in both DB and TP subgroups (Table). Patterns of overall and Grade ≥3 TEAEs between arms were similar regardless of prior tx. Higher rates of serious TEAEs were reported in TP pts (57%, 49%) than DB pts (44%, 40%) in R+P and PBO+P arms, respectively. Similar trend was observed for TEAEs leading to discontinuation for TP (40%, 30%) vs DB (29%, 22%) in respective tx arms. Baseline QoL scores were similar between tx arms within subgroups, but mean scores were > 5 points worse (range 0-100) for prior TP for role functioning, fatigue, pain, and appetite loss. Changes in mean scores were generally similar between arms and within subgroups. Conclusions: This exploratory analysis of RAINBOW suggests that although safety-related outcomes were less favorable in pts with prior TP, regardless of tx arm, similar improvements in efficacy were noted for R+P irrespective of prior DB or TP. Clinical trial information: NCT01170663 . [Table: see text]

3516 Background: We recently reported that clinical assessment of genomic biomarkers using ctDNA had advantages over tumor tissue-based sequencing for enrollment into matched clinical trials across a wide range of GI cancers. Herein we investigated the utility of ctDNA in non-CRC cancers in a SCRUM-Japan GI-SCREEN and GOZILA combined analysis. Methods: In GI-SCREEN, tumor tissue samples of pts with non-CRC were analyzed by a next generation sequencing (NGS)-based assay, Oncomine Comprehensive Assay, since Feb 2015. In GOZILA, plasma samples of non-CRC pts were analyzed by an NGS-based ctDNA assay, Guardant360, since Feb 2018. Results: As of Apr 2019, 2,952 pts in GI-SCREEN and 633 pts in GOZILA were enrolled. Baseline characteristics between the groups were well matched except that GOZILA included more pancreatic (P < 0.0001) and liver cancers (P = 0.016) but fewer gastric cancers (P < 0.0001) and GIST (P = 0.020) than GI-SCREEN. The success rates of the tests were 86.6% in GI-SCREEN and 87.3% in GOZILA (P = 0.649). Median turnaround time (TAT) was 37 days in GI-SCREEN and 12 days in GOZILA (P < 0.0001). The proportion of cases with actionable alterations detected (tissue vs blood; 29.8% vs 46.8%, P < 0.0001) and enrolled into matched clinical trials (4.8% vs 6.5%, P = 0.286) for each group by cancer type are shown in the Table. Pts with upper GI cancers, especially those in GOZILA, were more often enrolled into matched trials; trial enrollment for those with hepatobiliary and pancreatic (HBP) or other cancers was similar regardless of testing method. Median time from GI-SCREEN or GOZILA enrollment to clinical trial enrollment was 5.0 and 1.0 months (mo), respectively (P < 0.0001). Objective response rates (ORR) and progression-free survival (PFS) were not significantly different (tissue vs. blood; ORR: 14.6 vs. 26.3%, P = 0.30: median PFS: 3.3 vs. 2.6 mo, P = 0.71). Conclusions: Clinical sequencing of ctDNA, with its shorter TAT, contributed to rapid enrollment of non-CRC pts into matched clinical trials compared to those tested by tumor tissue sequencing, particularly for those with upper GI cancer, without compromising efficacy. Clinical trial information: UMIN000029315 . [Table: see text]

4011 Background: The IDEA collaboration for high-risk stage 2 colorectal cancer patients (pts) demonstrated that for CAPOX, 3 months was non-inferior to 6 months treatment, while for FOLFOX, 6 months was superior to 3 months treatment. We investigated the impact of high risk features on disease-free survival (DFS). Methods: ACHIEVE-2, one of the 4 IDEA studies (SCOT, TOSCA, ACHIEVE-2, HORG), was an open-label, multicenter randomized trial for high-risk stage II colon cancer. High risk features are defined as one or more: T4, inadequate nodal harvest < 12, poorly differentiated, clinical sign of obstruction and perforation or vascular invasion. The association of high risk features with DFS were measured by Cox regression analyses. Results: Between 2014 and 2017, ACHIEVE-2 enrolled 525 pts, out of whom 514 pts were the modified ITT (mITT) population; 432 received CAPOX (84.0%) and 82 did mFOLFOX6 (16.0%). High-risk features included 35.8% of T4, 12.8% of inadequate nodal harvest, 11.5% of poorly differentiated, 19.3% of obstruction, 6.4% of perforation and 87.5% of vascular invasion; 47.3% had one features, 35.2% had two, 14.6% had three, and 2.9% had four or more. With a median follow-up of 36.1 months, 3-year DFS rates were 88% in both arms, with a hazard ratio (HR) of 1.12 (95% CI, 0.67-1.87, p=0.67). In multivariate analysis, T4 (HR 3.77 [2.18-6.53], p< 0.0001) and inadequate nodal harvest (HR 2.98 [1.59-5.59], p= 0.0006) remained independent significant negative prognostic factors. The 3-year DFS rates in T4 and Non-T4 diseases were 78% and 94% (p

4069 Background: ACHIEVE, as part of the IDEA collaboration, was a multicenter trial randomizing patients with stage 3 resected colon cancer to either 3 versus 6 months of adjuvant FOLFOX/CAPOX. We previously reported that the hazard ratios (HRs) in disease-free survival (DFS) of 3 versus 6 months duration according to risk stage (low-risk [T1-3 and N1] or high-risk [T4 or N2]) and regimen (FOLFOX or CAPOX) as well as in overall population were consistent with those observed in the whole IDEA. This study aimed to clarify the significance of post-operative serum carcinoembryonic antigen (CEA) on DFS in stage 3 colon cancer. Methods: Eligibility included post-operative serum CEA value of ≤10 ng/ml at registration in the ACHIEVE trial, which enrolled 1313 patients between 2012 and 2014, out of whom 1291 pts were the modified ITT (mITT) population and used in this study. The cutoff values of CEA analyzed for prognostic analyses were the median value (1.8 ng/ml) in the mITT, the upper limit of normal (ULN) level (5.0 ng/ml), and the half of ULN (2.5 ng/ml). The association of post-operative CEA with DFS were measured by Cox regression analyses. Results: Of the 3 cutoff values, the ULN (5.0 ng/ml) was associated with DFS more strongly than the median (1.8 ng/ml) or half of ULN (2.5 ng/ml), with a HR of 1.75 (95%CI, 1.24-2.46) (Table). The 99 patients (7.7%) were identified as the CEA > ULN and 1192 (92.3%) as < ULN. In univariate analysis, regimen (CAPOX or FOLFOX), ECOG PS (0 or 1), T factor (T1-3 or T4), N factor (N1 or N2-3) and CEA ( < ULN or > ULN) were significantly associated with DFS. Multivariate Cox regression identified CEA > ULN as an independent poor risk factor (HR = 1.45; 95%CI, 1.03-2.05). Shorter DFS in patients with CEA > ULN than in those with CEA < ULN was consistently observed in each subgroup of baseline factors, including treatment duration, regimen, age, gender, PS, T-stage, N-stage, no of lymph nodes examined, and tumor location; no interaction was observed between CEA and these factors. Conclusions: Post-operative serum CEA is also a strong prognostic factor for DFS in stage 3 colon cancer. Clinical trial information: 000008543 . [Table: see text]

178 Background: Plasma vascular endothelial growth factor-D (VEGF-D) level is a potential predictor for ramucirumab efficacy in patients (pts) with metastatic colorectal cancer (mCRC), while a high VEGF-A and placental growth factor (PlGF) level in bevacizumab naïve pts receiving 2nd-line FOLFIRI plus aflibercept may suggest relatively higher activity. However, there are a few data associating 1st-line antiangiogenic treatments as well as anti-EGFR with angiogenic factors. Methods: This prospective longitudinal study aims to investigate an association between plasma angiogenesis-related mediators and clinical outcomes in mCRC. Serial plasma collections were done at time points of pre- and post-treatments of either 1st- or 2nd-line. Comprehensive measurements of 17 mediators were analyzed by the multiplex assay with Luminex technology. Here we report an association between levels of VEGF-D, PlGF and patient backgrounds. Results: From Sep 2017 to Aug 2019, 375 samples from 317 pts were enrolled in this analysis. Baseline characteristics were follows; 169 samples at pre-1st-line (pre-1L), 151 with prior bevacizumab treatment (post-bev) and 55 with prior anti-EGFR antibody (post-EGFR); median age, 66 years; male gender, 58%; RAS mutant, 46%; left-sided primary, 76%. In pre-1L, the median values of VEGF-D/ PlGF were 264/ 7.21 pg/mL without a clear association between the two in each patient (r = 0.094) and any baseline characteristics. Compared to pre-1L, the values of VEGF-D/ PlGF showed significantly higher in post-bev (median VEGF-D/ PlGF; 346/ 23.5 pg/mL, respectively). Moreover, there was no clear relationship between the two cytokines in each patient (r = 0.190). In 37 pts with serial blood collection, VEGF-D/ PlGF levels showed similar trends. In addition, VEGF-D/ PlGF levels in post-EGFR tended to be higher than those in pre-1L (median VEGF-D/ PlGF; 395/ 9.11 pg/mL, respectively). Conclusions: The VEGF-D/ PlGF may be separately induced by bev treatment as well as anti-EGFR therapy, suggesting the possibility of usefulness for selecting a better antiangiogenic inhibitor by measuring baseline VEGF-D/ PlGF. Clinical trial information: UMIN000028616.

229 Background: HER2 dual blockade showed the promise in clinical trials in patients (pts) with HER2-positive (HER2-Pos) metastatic colorectal cancer (mCRC). A phase I/II study of a novel anti-HER2 antibody-drug conjugate (HER2-ADC) showed promising activities across different cancer subtypes including HER2-Pos mCRC, and also showed a hint of activity for low-expressing (HER2-L) mCRC, regardless of RAS mutation. However, molecular landscape and prognostic value of HER2-L on mCRC are unclear. Methods: The eligibility included pts with mCRC who had undergone surgical resection of primary tumor. Using the specimen, HER2 expression was evaluated by immunohistochemistry (IHC) and FISH. Definition of HER2 positivity was as follows; HER2-Pos as IHC 3+ or IHC 2+/FISH positive: HER2-L as IHC 2+/FISH negative or IHC 1+: Negative (HER2-Neg) as IHC 0+. NGS tests were also done. Results: Between 2005 and 2015, a total of 370 pts were analyzed; 60% were male, with a median age of 64 y/o. Fifteen pts (4%) with HER2-Pos, 21 (6%) with HER2-L, and 334 (90%) with HER2-Neg were identified. Proportion of left-sided primary tumor was similar among groups ranging from 72% to 78%. No difference was observed in terms of major clinicopathological characteristics. The proportion of co-altered RAS mutations in HER2-L was significantly higher than HER2-Pos ( p = 0.037) and similar to HER2-Neg (27% in HER2-Pos vs. 62% in HER2-L vs. 56% in HER2-Neg). As of median follow-up of 24.8 months, median overall survival (mOS) in HER2-L was significantly better than that in HER2- Pos ( p = 0.029, 18.2 months in HER2-Pos vs. 33.3 in HER2-L vs. 27.9 in HER2-Neg). In 58 pts harboring RAS wild-type who received an anti-EGFR monoclonal antibody therapy, median progression-free survival (mPFS) in HER2-L tended to be better than that in HER2- Pos, with 2.2 months in HER2-Pos, 7.8 in HER2-L, and 5.5 in HER2-Neg ( p = 0.099). Conclusions: Since HER2-L mCRC had the high prevalence of co-altered RAS mutations but showed a better prognosis and might benefit more from an anti-EGFR therapy than HES2-Pos, the HER2-L mCRC seems to have a different biological behavior from HER2-Pos in terms of molecular landscape and prognostic value on mCRC.

107 Background: The anti–PD-1 antibody pembrolizumab (P) provides response rates of 28-57% in patients (pts) with MSI-H metastatic colorectal cancer (mCRC) vs 0% in those with non-MSI-H cancers. STAT3 has been previously reported as a potential key driver of immune evasion. This study investigates efficacy and safety for the combination of BBI608 (napabucasin), which blocks phosphorylated STAT3 and downregulates IDO1 and PD-L1, with P, in pts with mCRC. BBI608 480 mg BID with P was determined as the recommended phase II dose in phase I. Methods: Phase II included Cohorts A (MSI-H) and B (non-MSI-H). Pts with mCRC not responding to or intolerant of standard chemotherapies were enrolled. The primary endpoint was immune-related objective response rate (irORR), according to irRECIST. The sample size for Cohort A (10 pts) was derived in an exploratory manner. In Cohort B, assuming null and alternative hypotheses of irORR = 5% and 20% led to an estimated required sample size of 40 pts, with a 1-sided alpha of 5% and power of 90%. Genomic profiles and the consensus molecular subtypes (CMS) of colorectal cancer were determined by whole exome sequencing and RNA sequencing as previously described. Results: From Feb/2017 to Jun/2018, 10 pts were enrolled in Cohort A and 40 in Cohort B. The irORR was 50% (5 of 10 pts) in Cohort A and 10% (95% CI 2.8 to 23.7) (4 of 40 pts) in Cohort B. Of evaluable 19 pts for CMS classification in Cohort B, CMS1, CMS2, CMS3, and CMS4 were detected in 3, 6, 4, and 6 cases, respectively. The irORR was 33% (1 of 3 pts), 0% (0 of 6 pts), 25% (1 of 4 pts), 33% (2 of 6 pts) in CMS1, CMS2, CMS3, and CMS4, respectively. One CMS3 patient with partial response had POLE mutation, while 1 CMS1 and 2 CMS4 pts with partial response did not. The most common grade 3 or higher treatment-related adverse events included fever (10%) in Cohort A, and diarrhea (5%) and appetite loss (7.5%) in Cohort B, without unexpected safety signals. No treatment-related deaths occurred. Conclusions: BBI608 with P showed encouraging anti-tumor activity with acceptable toxicity for non-MSI-H mCRC pts as well as MSI-H mCRC pts. Impact of CMS on the efficacies of this combination warrants further investigation in the additional cohort of this study. Clinical trial information: NCT02851004.

438 Background: Neutrophil-to-lymphocyte ratio (NLR/N) reflects underlying levels of systemic inflammation and has prognostic value in advanced gastric cancer (G/GEJ). We investigated the relationship between pretreatment NLR and clinical outcomes in the RAINBOW study of ramucirumab (R) with paclitaxel (P) in G/GEJ. Methods: NLR is defined as the ratio of absolute neutrophil count and absolute lymphocyte count from peripheral blood. Pts in ITT population with baseline NLR were analyzed. As no clear NLR cutoff is established in G/GEJ, multiple cutoffs (4, 5, 6) were evaluated and relationships between baseline NLR and efficacy endpoints examined. Median OS, PFS were estimated using Kaplan Meier method; prognostic effects on OS/PFS of baseline NLR subgroups (sg) and treatment effects on OS/PFS within each baseline NLR sg were evaluated using univariate Cox PH models. Results: Baseline characteristics were generally balanced between high NLR sg. Higher baseline NLR groups were associated with worse outcomes regardless of cutoff [mOS N < 4 vs ≥4: 9.2 (8.1, 10.3) vs 5.6 (4.8, 6.6), HR = 0.61 (0.49, 0.75); N < 5 vs ≥5: 8.6 (7.8, 9.6) vs 5.3 (4.5, 6.5), HR = 0.59 (0.47, 0.75); N < 6 vs ≥6: 8.6 (7.8, 9.6) vs 4.7 (4.2, 5.9), HR = 0.55 (0.43, 0.70)]. Consistent treatment benefits (R+P vs Placebo (PB)+P) were observed within high baseline NLR sg (Table). No new safety signals were observed. Conclusions: In this exploratory analysis of RAINBOW, pretreatment NLR ( < 4, 5, 6) were independent prognostic factors of improved survival. Treatment benefits with R+P was preserved within high baseline NLR levels defined by different cutoffs and was consistent with ITT results. Clinical trial information: NCT01170663. [Table: see text]

5 Background: Blood-based genomic profiling by ctDNA analysis has a promise to potentially identify actionable genomic alterations. However, utility of clinical sequencing with ctDNA compared with that with tumor tissue for enrolling cancer pts to matched clinical trials remains unclear. Herein we investigated the utility of ctDNA clinical sequencing by the SCRUM-Japan GI-SCREEN and GOZILA Combined Analysis. Methods: In the GI-SCREEN, tumor tissue samples of pts with advanced GI cancer were analyzed by a next generation sequencing (NGS)-based assay, Oncomine Comprehensive Assay since Feb 2015. In the GOZILA, plasma samples of pts with advanced GI cancer were analyzed by an NGS-based ctDNA assay, Guardant360 since Feb 2018. Tests were performed centrally by CLIA-certified and CAP-accredited laboratories. Pts with actionable alterations were enrolled to matched company-sponsored or investigator-initiated clinical trials. Results: As of Apr 2019, test results were generated in 5,029 out of 5,743 pts (88%) in GI-SCREEN and 1,089 out of 1,103 pts (99%) in GOZILA ( P < 0.0001).Median turnaround time (TAT) was 35 days in GI-SCREEN and 12 days in GOZILA ( P < 0.0001). There were no differences in other baseline characteristics between GI-SCREEN and GOZILA. Proportion of enrolling matched clinical trials in GOZILA was significantly higher than that in GI-SCREEN (126 pts [2.2%] in GI-SCREEN vs. 60 pts [5.4%] in GOZILA, P < 0.0001). Median time from GI-SCREEN or GOZILA enrollment to clinical trial enrollment was 5.9 and 1.0 months (mo), respectively ( P < 0.0001). The objective response rate (ORR) and progression-free survival (PFS) were not significantly different (ORR: 17.5 vs. 16.7%, P = 1.00; median PFS: 2.8 vs. 2.0 mo, P = 0.24). Conclusions: Clinical sequencing with ctDNA having the advantage of the shorter TAT enrolled more pts with advanced GI cancer to matched clinical trials than those with tumor tissue, without compromising the efficacy. Clinical trial information: UMIN000029315.

145 Background: FTD/TPI has shown clinical benefit and consistent safety in pretreated pts with metastatic colorectal cancer (mCRC) and metastatic gastric or gastroesophageal junction cancer (mGC/GEJC) in the phase 3 RECOURSE and TAGS trials, respectively. HeAEs were the most frequent AEs with FTD/TPI treatment. Methods: Pts in this analysis received ≥1 FTD/TPI dose in the TAGS and RECOURSE trials. Subgroups included pts with normal renal function (nRF; CrCl ≥90 mL/min), mild RI (CrCl 60–89 mL/min), moderate (mod) RI (CrCl 30–59 mL/min), normal hepatic function (nHF) and mild HI (total bilirubin ULN). Results: FTD/TPI was administered to 868 pts in the overall pooled population (OPP; n=335, TAGS [mGC/GEJC]; n=533, RECOURSE [mCRC]); 52%, 36%, and 11% had nRF, mild and moderate RI, and 66% and 33% had nHF and mild HI, respectively. Frequencies of any-cause grade (gr) ≥3 HeAEs were similar across subgroups and the OPP, except for gr ≥3 anemia and gr ≥3 leukopenia, which were higher with mod RI (table). In the OPP, most gr 3/4 neutropenia events occurred within the first 2 cycles (median time to onset [mTTO], 49 d). Median time to resolution (mTTR) was 8 d. Gr 3/4 neutropenia TTO and TTR in most subgroups were consistent with the OPP, except with mod RI (mTTO, 29 d). HeAE management and correlative efficacy analyses will be presented. Conclusions: In this pooled analysis of pts with mCRC and mGC/GEJC, HeAEs with FTD/TPI in pts with mild to mod RI and mild HI were manageable and not largely different from those in the OPP. Clinical trial information: NCT02500043 and NCT01607957. [Table: see text]

4039 Background: FTD/TPI was approved in 2015 for pretreated pts with mCRC based on the phase 3 RECOURSE trial. FTD/TPI recently demonstrating significantly improved overall survival vs placebo in pretreated pts with mGC/mGEJC in the phase 3 TAGS trial. Methods: We evaluated the pooled safety of FTD/TPI in TAGS and RECOURSE in all pts who received ≥1 dose of FTD/TPI (safety population). Pts were required to have ECOG PS 0/1 and to have received ≥2 previous chemotherapy lines. Results: FTD/TPI and placebo were administered to 335 and 168 pts, respectively, in TAGS, and 533 and 265 pts in RECOURSE. Baseline characteristics were balanced across treatment groups and reflected the disease populations. In the pooled population, 66% of pts were men and 75% had received ≥3 prior systemic treatments. The safety profile of FTD/TPI was comparable between studies (table). In TAGS and RECOURSE, the most common any-cause grade (gr) ≥3 AEs in FTD/TPI-treated pts were neutropenia (34%; 35%), anemia (19%; 17%), and leukopenia (9%; 13%). Gr ≥3 febrile neutropenia occurred in 2% and 4% of pts and gr ≥3 GI AEs in 21% and 12%. Gr ≥3 cardiac AEs were reported in 1% of FTD/TPI-treated pts (both studies), in contrast to results obtained with other third-line agents. Similar proportions of FTD/TPI-treated pts in both studies had AEs leading to dosing delay, dose reduction, or treatment discontinuation. Dosing delay was used more often than dose reduction to manage AEs. TRAEs leading to death occurred in one FTD/TPI-treated pt ( < 1%) in each trial. Conclusions: In a pooled analysis, FTD/TPI was well tolerated with a consistent safety profile in pts with mGC/mGEJC or mCRC. The most frequent AEs were hematologic and GI, which were managed with dosing delays/dose reductions. Clinical trial information: NCT02500043; NCT01607957. [Table: see text]