Kadowaki S, et al. – Experts sought to figure out if a depth of response (DpR) was associated with clinical outcomes in human epidermal growth factor receptor 2 (HER2)–positive AGC patients treated with trastuzumab–based chemotherapy. In these patients, higher DpR predicted favorable outcomes following trastuzumab–based chemotherapy.

Methods

• This study entailed fifty-seven HER2-positive AGC patients who were treated with trastuzumab in combination with fluoropyrimidines plus cisplatin therapy as first-line treatment.
• They defined DpR as the percent maximal tumor shrinkage of target lesions observed at the lowest point compared with baseline.
• It was noted that the cutoff DpR level to discriminate better survival was based on receiver-operating characteristic curve analysis.
• The multivariable Cox proportional hazards model was used to appraise association of DpR with progression-free survival (PFS) and overall survival (OS).

Results

• 56.8% (range -37.9 to 100%) was the median DpR level.
• In multivariate models adjusted for relevant variables, an association of DpR, as a dichotomized variable with a cutoff level of 50% and a continuous variable, with PFS (hazard ratio [HR] 0.39 and 0.97; 95% confidence interval [CI] 0.22–0.68 and 0.96–0.98) and OS (HR 0.38 and 0.98; 95% CI 0.21–0.70 and 0.97–0.99), was observed.
• Between the high DpR (≥50%) and the low DpR groups (<50%), clinically meaningful differences in PFS (median, 9.8 vs. 4.1 months; p < 0.001) and OS (median, 24.7 vs. 12.8 months; p < 0.001) were observed.