Similar trends in serum VEGF-D levels and kidney angiomyolipoma responses with longer duration sirolimus treatment in adults with tuberous sclerosis

Abstract

Context: We have previously shown that serum VEGF-D is elevated at baseline, correlates with kidney angiomyolipoma size at baseline and 12 months, and decreases with sirolimus treatment in adults with tuberous sclerosis complex (TSC). To further investigate the utility of serum VEGF-D for longer term monitoring of TSC kidney disease, we present VEGF-D level results with 24 month follow-up.

Objective: To compare 24 month VEGF-D levels in two subgroups of sirolimus treated patients (OFF SIROLIMUS AFTER 12 MONTHS or ON SIROLIMUS AFTER 12 MONTHS). DESIGN AND INTERVENTION(S): Serum VEGF-D was measured in samples collected from subjects enrolled in a phase 2 multicenter trial evaluating sirolimus for the treatment of kidney angiomyolipomas associated with TSC or TSC/LAM. All participants were treated with sirolimus from 0-12 months. During months 12-24, sirolimus was discontinued in one subgroup. The other subgroup was treated with additional sirolimus.

Setting: Adult TSC participants were recruited from six clinical sites in the United States (comprehensive TSC clinics, 5; urology clinic, 1).

Patients: There were 28 TSC patients who completed all 24 months of the study and serum samples were available at 24 months from 18/28 patients.

Main outcome measure(s): We compared the percent change in VEGF-D levels (baseline to 24 months) in patients from the two treatment subgroups.

Results: At 24 months, VEGF-D levels decreased by 67% compared with baseline (to 787 ± 426 pg/ml) in the ON SIROLIMUS AFTER 12 MONTHS group versus a 13% decrease (to 2971 ± 4014 pg/ml) in the OFF SIROLIMUS AFTER 12 MONTHS group (p=0.013, Mann-Whitney test). A similar trend was observed in kidney angiomyolipoma size but not in pulmonary function tests. Conclusions Serum VEGF-D may be useful for monitoring response to treatment with sirolimus and kidney angiomyolipoma size in patients with TSC, but confirmation is needed.

Trial registration: Clinical trials.gov NCT00126672.

Figure 1. Enrollment and VEGF-D sample chart.

Figure 2. Percent change in serum VEGF-D levels and kidney angiomyolipoma size with sirolimus treatment at 12 and 24 months.

A) The blue bars show the mean percent change in serum VEGF-D levels with sirolimus treatment at 12 months for two treatment subgroups. The red bars show 24 month data. Error bars indicate standard error; p = 0.013 at 24 months and NS (p = 0.065) at 12 months. B) Changes in kidney angiomyolipoma size showed a similar trend. The blue bars show the mean percent change in kidney angiomyolipoma size at 12 months for two treatment subgroups. The red bars show the data for year 2 (24 months). Error bars indicate standard error; p = 0.022 at 24 months and NS (p = 0.54) at 12 months.

Figure 3. Individual trends in serum VEGF-D levels from subjects with TSC and angiomyolipomas who were treated with sirolimus.

VEGF-D levels were measured at baseline before sirolimus was started, and at 4, 8, 12, and 24 months. A) All subjects; B) Subset OFF SIROLIMUS AFTER 12 MONTHS (n = 12, in black); C) Subset ON SIROLIMUS AFTER 12 MONTHS (n = 6, in red); D) Mean VEGF-D levels ± standard error (SEM) for both subsets. Panels E–H) Trends in VEGF-D serum levels and changes in kidney tumor size for individual subjects over time from baseline to 24 months. As indicated, panels E and F show trends for individual subjects (#28-with TSC/LAM and #20-with TSC only) in the OFF SIROLIMUS AFTER 12 MONTHS group; panels G and H show data for the ON SIROLIMUS AFTER 12 MONTHS group (#25-with TSC/LAM and #16-with TSC only). The trends in VEGF-D levels are similar to the trends in kidney angiomyolipoma size in both treatment subgroups.