a) MVD of B-cell lymphomas from two independent cohorts of mice (n=16) randomized to receive Roflumilast or vehicle control show a significantly suppressed angiogenesis in mice treated with the PDE4 inhibitor (p=0.03 and p=0.01, cohorts 1 and 2 respectively, two-tailed Student’s t-test). Data shown are mean vessel number from three hot-spots ± SEM; each dot in the graph represents a unique tumor b) MVD of B-cell lymphomas from a third independent cohort of mice (n=8) randomized to receive Roflumilast or vehicle control show a significantly suppressed angiogenesis in mice treated with the PDE4 inhibitor in association with diminished serum levels of VEGFA (p=0.04 and p=0.005 left and right graphs, respectively, two-tailed Student’s t-test). Data shown are mean vessel number from three hot-spots or VEGF quantification ± SEM; each dot in the graph represents a unique tumor. Representative CD34 IHC of murine B-cell lymphomas are shown in the bottom panel. The bar indicates 100μm c) Top graph - Kaplan-Meier survival curves of mice bearing isogenic Eu-myc lymphomas treated with vehicle or Roflumilast. The log-rank test showed a significantly improved survival rate in the Roflumilast-treated mice (n=36, p=0.01). Bottom graph – lymphomas excised from Roflumilast-treated mice were significantly smaller than those derived from mice treated with a vehicle control (p<0.0001, two-tailed Student’s t-test, n=33). Representative examples of lymphomas collected from these mice are shown on the right. d) Circulating levels of VEGFA and tumoral PI3K activity (top and bottom graphs, respectively) were significantly lower in mice randomized to receive Roflumilast than in vehicle control treated mice (p=0.04 and p<0.0001, respectively, two sided Student’s t-test). Data shown are mean ± SEM of 30 mice and 28 tumors, respectively; PIP3 levels were measured in triplicates. Right panel - western blot examination of primary murine B-cell lymphomas indicate that AKT phosphorylation (T308) is significantly suppressed following Roflumilast administration (p=0.003, two-tailed Student’s t-test – densitometric pAKT values, normalized by totaL AKT, n=22).