P-057 - A retrospective analysis for patients with HER2 positive gastric cancer who were treated with trastuzumab-based chemotherapy

Date 04 July 2015
Event WorldGI 2015
Session Posters
Topics Anti-Cancer Agents & Biologic Therapy
Biomarkers
Gastric Cancer
Presenter J.H. Yi
Citation Annals of Oncology (2015) 26 (suppl_4): 1-100. 10.1093/annonc/mdv233
Authors J.H. Yi1, J.H. Kang2, I.G. Hwang3, H.K. Ahn4, S.I. Lee5, Y.-. Won6, J.H. Ji7, H.S. Kim8, S.Y. Rha2, S.Y. Oh8, K.E. Lee9, T.L. Lim10, C.H. Maeng11, S.T. Kim2, J. Lee2, J.O. Park2, Y.-. Park12, H.Y. Lim13, W.K. Kang2, S.H. Park12
  • 1Hanyang University, Seoul/KR
  • 2Gyeongsang National University School of Medicine, Jinju/KR
  • 3CAU, Seoul/KR
  • 4Gachon Hospital, Incheon/KR
  • 5Dankook University School of Medicine, Cheonan/KR
  • 6Guri Hospital, Guri/KR
  • 7Samsung Changwon Hospital, Changwon/KR
  • 8Dong-A University College of Medicine, Busan/KR
  • 9Ewha University, Seoul/KR
  • 10Central VHS medical center, Seoul/KR
  • 11Kyung Hee University School of Medicine, Seoul/KR
  • 12Sungkyunkwan University School of Medicine, Seoul/KR
  • 13Sungkyunkwan University, Seoul/KR

Abstract

Introduction

After ToGA trial, trastuzumab-based chemotherapy became the standard option for managing patients with HER2 (+) metastatic gastric cancer (GC). However, the OS benefit was not found in Asian and diffuse-type cancer patients. The aim of the current study is to investigate predictive markers for trastuzumab-based chemotherapy for HER2 (+) GC.

Methods

We retrospectively analyzed the medical records of the patients with HER2 (+) (IHC3(+) or IHC2(+)/FISH(+)) GC who were treated with trastuzumab-based chemotherapy. The ORR, PFS, and OS were compared according to the patients' clinicopathologic features and data of ToGA trial.

Results

A total of 168 Asian patients from 12 institutes in South Korea were collected. The median age was 60 (range 27-85) and the male:female ratio was 118 (70.2%): 50 (29.8%). Regarding the primary sites, 161 (95.8%) had stomach cancer and 7 (4.2%) had GEJ cancer. Fourteen (8.3%), 63 (37.5%), 75 (44.6%) and 11 (6.5%) patients had well, moderately, poorly differentiated tubular adenocarcinoma (TAC) and signet ring cell carcinoma (SRC), respectively. The ORR was 50.6% (85/168), which was not significantly different to that of the ToGA trial (47%, p = .493). With median follow-up duration of 32.9 months (95% CI 30.0–35.8), median PFS was 10.2 month (95% CI 8.7–11.7), and median OS was 18.5 months (95% CI 16.4–50.6). These numerical data are slightly better than those of the ToGA trial (PFS, 6.7 months; OS, 16.0 months). Next, we investigated if PDH (poorly differentiated histology, poorly differentiated TAC + SRC) affected on clinical outcomes. Consequently, 86 (51.2%) patients were classified as PDH group. The median PFS (8.9 months vs. 11.5 months, p = 0.16) were slightly inferior in PDH patients but still, it was better than the PFS of the ToGA trial. The median OS was significantly shorter for PDH patients (14.6 months vs. 19.0 months, p = 0.025), but still, it was comparable to that of the ToGA trial. ECOG status 0 and serum albumin level higher than 3.0 g/dl were also associated with improved survival. In 59 patients who were FISH (+), higher HER2/CEP17 ratio was not associated with improved survival.

Conclusion

While subset analysis of ToGA trial has demonstrated that trastuzumab-based chemotherapy may not be beneficial for Asians and patients with PDH, our real world data suggested that even in Asian and patients with PDH, trastuzumab-based chemotherapy is associated with improved clinical outcomes in patients with HER2 (+) gastric cancer.

Figure: P-057