K. Chin

O1-13-4LOWER CEA AND CA19-9 LEVELS MAY PREDICT LONGER PFS IN PATIENTS WITH HER2 POSITIVE GC TREATED BY T-mab BASED CHEMOTHERAPY

Abstract Background: ToGA study showed significant survival benefit of trastuzumab (T-mab) in patients with HER2 positive gastric cancer (GC); however, clinical factors which can predict its efficacy prior to treatment are still unknown. We examined associations between clinical factors and prognosis in patients with HER2 positive GC treated by T-mab based chemotherapy. Methods: Fourty-two HER2 positive GC patients, who were treated by T-mab with chemotherapy in our institute from 2011 March to 2013 September, were enrolled. We retrospectively analyzed whether baseline clinical factors according to ToGA study and tumor markers could impact progression-free survival (PFS) and overall survival (OS). These endpoints were estimated using by Kaplan-Meier methods and compared by the log-rank test. Results: Median follow-up period was 12.9 months. Median age was 61.4 y.o. and 62% of the patients were male. PS 0-1, GEJ cancer, visceral metastasis (lung or liver), previous gastorectomy, previous chemotherapy, number of metastatic site (1-2), and number of metastatic lesion (1-4) were found in 98%, 29%, 57%, 31%, 19%, 79%, and 24% of the patients, respectively. Sixty-nine% and 93% of the patients were differentiated type and HER2 3+ by IHC, respectively. Median baseline CEA and CA19-9 levels were 5.6 ng/ml and 91.6 U/ml, respectively. Median PFS was 9.5 months (95% CI: 5.5-13.5) and median OS was not reached, respectively. Overall response rate by RECIST was 64%. In the univariate analysis, lower CEA levels were associated with longer PFS (HR: 0.42 [95%CI: 0.20-0.91], p = 0.024). In addition, lower CA19-9 levels were also associated with longer PFS (HR: 0.36 [95%CI: 0.17-0.78], p = 0.007). In the multivariate analysis, these associations retained significant both in CEA (HR: 0.42 [95%CI: 0.19-0.92], p = 0.03) and CA 19-9 (HR: 0.36 [95%CI: 0.16-0.78], p = 0.010), respectively. No clinical factors were associated with OS. Conclusions: Lower baseline CEA and CA19-9 levels may predict longer PFS.

527PA PHASE I/II STUDY OF BI-WEEKLY XELIRI WITH CAPECITABINE 1,000 MG/M2 TWICE DAILY AND IRINOTECAN 180 MG/M2 PLUS BEVACIZUMAB(BV) FOR PATIENT WITH METASTATIC COLORECTAL CANCER AS SECOND-LINE CHEMOTHERAPY (BIXER STUDY)

ABSTRACT Aim: Tri-weekly XELIRI is not completely regarded as a valid substitute for FOLFIRI in mCRC because of the potential for greater toxicity. Reduced dose tri-weekly XELIRI is officially recommended recently. This time, we conducted a PI/II study to assess bi-weekly XELIRI plus BV in efficacy and safety as second-line chemotherapy in mCRC. Methods: Patients with prior chemotherapy including oxaliplatin and BV for mCRC, wild or hetero type of UGT1A1 *6*28 were eligible for this study. Treatment comprised capecitabine 1,000 mg/m2 twice daily from the evening of day 1 to the morning of day 8, intravenous irinotecan on day 1, and BV 5mg/kg on day 1 every two weeks. PI study was composed of two steps (irinotecan 150 and 180 mg/m2), and dose limiting toxicity was assessed during the first treatment cycle. The primary endpoint of PII study was progression-free survival (PFS). Results: Recommended dose of irinotecan was determined as 180mg/m2 in PI study. Between Nov 2010 and Aug 2013, 44 patients were enrolled in PII study. Characteristics of patients were as follows (N = 44): median age, 60 yrs (range 32-80 yrs); male/female, 21/23; ECOG PS0, 86.4%; colon/rectum, 23/21; UGT1A1 wild/hetero type, 29/15; and 1st chemo regimen FOLFOX/XELOX, 18/26. The median number of treatment cycles was 10.5. Median PFS was 6.8 months (95%CI, 5.3-8.2 months), and the primary endpoint was met. Median overall survival (OS) was 18.3 months (95%CI, 13.4 - 23.1 months). Response rate was 22.7% (95%CI, 9.8-35.6%). No significant differences in PFS or OS occurred in UGT1A1 status and 1st chemo regimen. Grade 3 or greater adverse events observed were: neutropenia in six, diarrhea in five, nausea in four, anorexia in one, vomiting in one, stomatitis in one, fatigue in one, hand-foot skin reaction in one, hypertension in one, and interstitial pneumonia in one. There were no other severe adverse events and treatment related deaths. Conclusions: In mCRC patients with wild or hetero of UGT1A1*6*28 genotype, biweekly XELIRI + BV is effective and feasible as 2nd line chemotherapy. Bi-weekly XELIRI + BV could be a valid substitute for FOLFIRI + BV in mCRC. Disclosure: All authors have declared no conflicts of interest.