Early tumor shrinkage (ETS) and deepness of response (DpR) is an efficacy outcome measure in metastatic colorectal cancer patients receiving chemotherapy plus epidermal growth factor receptor (EGFR) inhibitor. Trastuzumab is a monoclonal antibody against EGFR2 (HER2). It is controversial whether ETS and DpR is an efficacy outcome measure in HER2-positive advanced gastric cancer (HPAGC) or not. We aimed to evaluate the relationship between clinical outcome and ETS, DpR in HPAGC patients treated with 1st-line chemotherapy and trastuzumab (CT).
A total of 100 patients with histopathologically confirmed HPAGC treated with 1st-line CT between March 2011 and November 2015 were enrolled retrospectively. OS was defined as the time from the first day of treatment to death from any cause. PFS was defined as the time from the first day of treatment to either the first objective evidence of disease progression or to death from any cause. ETS was defined relative change in the sum of the longest diameters at week 8 (±4) compared to baseline. (Cut-off :20%). DpR was defined relative change in the sum of the longest diameters at the nadir compared to baseline. (Cut-off :median).
The median duration follow up at the time of the analysis was 19.8 months (14.9-25.1). An overall RR and the disease control rate were 64% and 87%, respectively (CR2, PR 62, SD 23, PD13). The median PFS was 7.9 months (5.8-11) and the median OS was 20.8 months (14.3-24.8). Median DpR of 44% (interquartile range: 16%, 55%) The median period until DpR was 9.5 weeks. ETS ≧ 20% was associated with significantly longer OS and PFS when compared with ETS
These results indicate the potential of both ETS and DpR as a new measure of efficacy in HPAGC patients treated with 1st-line CT.
Clinical trial identification
Legal entity responsible for the study
All authors have declared no conflicts of interest.