1367P Predictive clinical characteristics for body weight gain in patients treated with alectinib: Analyses of J-ALEX, ALUR, and ML29453

Alectinib has emerged as one of the anaplastic lymphoma kinase (ALK) directed therapy of choice in patients with advanced ALK+ non-small cell lung cancer (NSCLC). Body weight gain is a side effect reported in 12% of patients, caused by an increased amount of body fat. Baseline waist circumference has been found to be a positive predictor of the increase in visceral adipose tissue. We hypothesize that baseline body mass index (BMI) is positively associated with body weight gain. Individual data from patients treated with alectinib were obtained via Vivli data-sharing platform. Studies with body weight data were selected. All body weight measurements during the first year of treatment were included. A mixed-effects model with random intercept was conducted to assess the trend of % change in body weight over time and to explore the effect of baseline characteristics on % change in body weight from baseline. Three prospective trials with body weight data were eligible (J-ALEX, ALUR, ML29453). All 309 patients were included in the analysis. During the first year of treatment, 2632 measurements of body weight were documented. Data from J-ALEX (n=103) was analyzed separately, as reference values for BMI differ between Japanese and Western populations. Percent change in body weight increased significantly over time in the mixed-model analyses in both J-ALEX (β = 0.48, p < 0.001) and ALUR/ML29453 (β = 0.31, p = 0.001). In the ALUR/ML29453 dataset there was an association between baseline albumin level and % change in body weight (β = 0.08, p = 0.003). A maximum body weight gain of ≥ 10% during the first year was observed in 23 patients (22.3%) in J-ALEX and 31 patients (15.0%) in ALUR/ML29453.Table: 1367PBaseline characteristicsJ-ALEXML29453MO28928n = 103n = 129n = 77PopulationJapanUSAEurope and AsiaBaseline characteristicsAge (in years)59 ± 1455 ± 1354 ± 12Sex (M) (%)39.843.458.4Weight (kg)55.9 [12.8]70.5 [19.6]70.0 [23.3]Baseline BMI (kg/m2)21.9 [3.8]24.1 [6.8]25.8 [5.7]Albumin baseline (g/L)39 [7]38 [6]37 [9] Open table in a new tab . A significant and clinically relevant increase in body weight was observed in the first year of treatment with alectinib. Baseline BMI was not predictive for body weight gain. Informing patients before start of alectinib is strongly recommended.