Abstract C143: Utility of growth modulation index and tumor growth rate to evaluate efficacy in metastatic gastric cancer patients

Background Growth modulation index (GMI) and tumor growth rate (TGR) have been proposed as signs of activity in early phase clinical trials. We explored utility of the efficacy end points in metastatic gastric cancer. Patients and Methods We carried out a retrospective study in metastatic gastric cancer patients receiving weekly paclitaxel regimen as second or more line treatment between 2005 and 2013 in Yonsei Cancer Center, and evaluate the association of GMI and TGR with efficacy outcomes respectively. The growth modulation index (GMI) was defined the ratio of time to progression with the nth line (TTPn) of therapy to the TTPn−1 with the n-1th line. TGR was computed during the pretreatment period (reference) and the experimental period. Comparisons used chi-squared and log-rank tests. Results A total of 133 patients were enrolled in this study. The median TTPn was 2.7 months, whereas the median TTPn−1 was 5.3 months. Thirty-one patients experienced GMI > 1.2 (23.3%). Median OS was highly correlated with GMI: 6.3 and 7.5 months with GMI ≤ 1.2 and GMI > 1.2 (P = 0.0009). TGR could be evaluated in 52 patients. Among them, 37 patients (71.1%) exhibited a decrease in TGR. The decrease of TGFR was associated with PFS (P = 0.043) and OS (P = 0.045). Conclusions GMI and TGR seem to be interesting end points that provides additional information compared with classical criteria. GMI >1.2 and decrease of TGR are associated with significant OS improvement. Citation Format: Seung-Hoon Beom, Minkyu Jung, Hyo Song Kim, Joong Bae Ahn, Sun Young Rha, Hyun Cheol Chung. Utility of growth modulation index and tumor growth rate to evaluate efficacy in metastatic gastric cancer patients. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C143.