Fig. 4

Platelet aggregation is reduced in RCC patients after 2 weeks of sunitinib treatment and correlates with reduction in platelet count. Blood was collected from 10 healthy controls and 20 RCC patients the day before, after 2 weeks, 4 weeks and 3 months on sunitinib treatment. A Light transmission aggregometry was induced in isolated platelets (250 × 10⁹/L) by collagen type I. Scatterplots indicate percentage of aggregation normalized to aggregation pre-treatment. Circles indicate platelets from patients treated with sunitinib, stimulated with 1 μg/mL collagen; diamonds indicate platelets from patients treated with sunitinib and anti-platelet drugs, stimulated with 5 μg/mL collagen. Individual dots in the scatterplots represent one patient, for color coding see Table 1. Lines and error bars represent median ± interquartile range (n = 10-20), *P < 0.05. B Correlation between difference in platelet count (ΔPlt count = Plt count at 2 weeks on treatment – platelet count before treatment) and difference in platelet aggregation (ΔPlt aggregation = Maximum amplitude at 2 weeks on treatment – maximum amplitude before treatment). Individual dots in the scatterplots represent one patient, for color coding see Table 1. C Correlation of significant R values for (changes in) platelet count, change in aggregation response and (N-desethyl-)sunitnib concentration parameters, with a highly negative correlation in green, a highly positive correlation in orange and no correlation in white. D Rotated component matrix determined by principal component analysis. Heatmap shows relative contribution of parameters to the four components (C1-4) with an eigenvalue over 1. Heatmap was filtered to only include values greater than 0.4 or less than − 0.4 as important contributors to the determined component. Colors refer to a highly negative contribution in green, a highly positive contribution in orange and no correlation in white