Understanding Vitamin D's Role in Cancer Care
In a recent study, short-term, high‑dose vitamin D3 supplementation administered to vitamin D–insufficient patients with cancer— including a subset who received pembrolizumab —produced rapid shifts in peripheral immune-cell composition and improvements in markers of genomic integrity.
This exploratory pre/post cohort enrolled a small pilot group of vitamin D–insufficient cancer patients who received a short-term, high-dose regimen (30,000 IU/week for two months) to normalize serum 25(OH)D, with a subset receiving pembrolizumab in parallel. The design used PBMC-resolved single-cell chromatin accessibility and molecular assays.
Laboratory analyses showed an average ~26% rise in monocytes (with markedly larger increases in the pembrolizumab subgroup) and increased natural killer cell proportions, alongside improved DNA integrity measured by the Comet assay (significant reductions in mononuclear-cell comet-tail percentage, p=0.01).
Mechanistically, telomere measurements and ATAC‑Seq data aligned with the cellular findings, showing coordinated shifts in chromatin accessibility across immune subsets that could plausibly modify immune surveillance, but these molecular endpoints were short-term and derived from a heterogeneous pilot cohort, so clinical consequences remain provisional.
Key Takeaways:
- Short-term, high-dose Vitamin D3 normalization produced measurable PBMC composition shifts and improved DNA integrity in a pilot oncology cohort.
- Combined Vitamin D3 and pembrolizumab treatment amplified immune-cell changes, suggesting an interaction between repletion and checkpoint inhibition that warrants further testing.