(48) Efficacy and Safety of a Personalized Vitamin D3 Loading Dose Followed by 2,000 IU Per Day to Raise Serum 25-Hydroxyvitamin D Levels in Colorectal Cancer Patients with Vitamin D Insufficiency. Interim Analysis of a RCT

Publication Number: 722

Background: Vitamin D insufficiency, defined by 25-hydroxyvitamin D (25(OH)D) levels < 50 nmol/L, is common among colorectal cancer patients, especially shortly after tumor surgery. An approach using a personalized vitamin D3 loading dose to rapidly increase 25(OH)D has not yet been tested in cancer patients.

Objectives: The objectives of the interim analysis are to test whether there are differences in serum 25(OH)D levels, the prevalence of adequate vitamin D status (25(OH)D ≥ 50 nmol/L), and frequencies of the safety parameters hypervitaminosis D, hypercalcemia, hypercalciuria, and severe renal impairment in the vitamin D3 and placebo group at visit 1 (trial day 12-21, end of loading dose) and visit 2 (trial week 13-16, end of maintenance dose).

Methods: The VICTORIA trial (EudraCT-No: 2019-000502-30) is a randomized, double-blind, controlled trial. Overall, 456 colorectal cancer patients aged 18 years and older will be recruited in up to nine German rehabilitation clinics. Study inclusion requires a diagnosis of non-metastatic colorectal cancer, surgical removal of the tumor within the past 12 months and 25(OH)D) levels < 50 nmol/L.
The personalized loading dose is calculated from baseline 25(OH)D level and BMI and is followed by a maintenance dose of 2,000 IU vitamin D3 daily until end of trial after 12 weeks.
Wilcoxon rank-sum test for continuous and Fisher’s exact test for dichotomous variables were used.

Results: This abstract shows the results of the first n=74 unblinded study participants of whom n=68 (n=36 verum, n=32 placebo) could be included in the intention-to-treat analyses at visit 1 and n=52 at visit 2.
In the placebo group, the mean 25(OH)D levels (95% confidence interval (CI)) at screening (28.4 (24.3 - 32.5) nmol/L) did not change much until visit 1 (31.6 (27.3 - 35.8) nmol/L) and visit 2 (35.1 (28.5 - 41.8) nmol/L). In the verum group, the mean 25(OH)D levels at screening (26.0 (22.8 - 29.3) nmol/L) increased until visit 1 (64.6 (58.3 - 67.9) nmol/L) and visit 2 (72.4 (66.2 - 78.5) nmol/L). The prevalence of adequate vitamin D status in the placebo and verum group was 6.3% and 80.6% at visit 1 and 18.5% and 96.0% at visit 2, respectively. All comparisons between the trial arms were highly statistically significant (p < 0.0001).
No events for the safety parameters were observed, except for 5 cases of hypercalciuria in the verum and 1 case in the placebo group at visit 1 (p=0.202). The study medication was discontinued and a normalization of urinary calcium levels was observed at visit 2.

Conclusions: The personalized vitamin D3 loading dose was substantially more effective than placebo in increasing 25(OH)D levels, and the maintenance dose of 2,000 IU vitamin D3 per day successfully maintained the achieved levels. Hypercalciuria may occur but is reversible.